What the processor crystal consists of. How processors are made: Mapper technology versus Intel. How to check if the processor is working

The roots of our digital lifestyle certainly stem from semiconductors, which have enabled the creation of sophisticated transistor-based computing chips. They store and process data, which is the basis of modern microprocessors. Semiconductors, which are now made from sand, are a key component of almost any electronic device, from computers to laptops to cell phones. Even cars are no longer without semiconductors and electronics, as semiconductors control the air conditioning system, fuel injection, ignition, sunroof, mirrors and even steering (BMW Active Steering). Almost any device that consumes energy today is based on semiconductors.

Microprocessors are undoubtedly among the most sophisticated semiconductor products, as the number of transistors will soon reach a billion, and the spectrum of functionality is amazing today. Soon there will be dual-core Core 2 processors on an almost finished 45-nm process technology from Intel, and they will already contain 410 million transistors (although most of them will be used for 6 MB L2 cache). The 45nm process is named for the size of a single transistor, which is now about 1,000 times the diameter of a human hair. To a certain extent, this is why electronics begins to control everything in our life: even when the size of the transistor was larger, it was very cheap to produce not very complex microcircuits, the budget of transistors was very large.

In this article, we will cover the basics of microprocessor manufacturing, but also touch on the history of processors, architecture, and look at different products on the market. You can find a lot of interesting information on the Internet, some of which are listed below.

• Wikipedia: Microprocessor ... This article covers the different types of processors and provides links to manufacturers and additional Wiki pages about processors.
• Wikipedia: Microprocessors (Category) ... See the microprocessor section for even more links and information.

PC competitors: AMD and Intel

Founded in 1969, Advanced Micro Devices Inc. is headquartered in Sunnyvale, California, while the heart of Intel, which was formed just a year earlier, is located a few kilometers away in Santa Clara. AMD has two factories today: in Austin (Texas, USA) and in Dresden (Germany). A new plant will be operational soon. In addition, AMD has partnered with IBM for processor technology development and manufacturing. Of course, this is all just a fraction of Intel's size, as this market leader now has nearly 20 factories in nine locations. About half of them are used for the manufacture of microprocessors. So when you compare AMD and Intel, remember that you are comparing David and Goliath.

Intel has an undeniable advantage in the form of huge manufacturing facilities. Yes, the company is today a leader in the implementation of advanced technological processes. Intel is about a year ahead of AMD in this regard. As a result, Intel can use more transistors and more cache in its processors. AMD, unlike Intel, has to optimize the process technology as efficiently as possible in order to keep up with the competitor and release decent processors. Of course, the design of processors and their architecture are very different, but the technical manufacturing process is built on the same basic principles. Although, of course, there are many differences in it.

Microprocessor manufacturing

The manufacturing of microprocessors has two important steps. The first is the manufacturing of the substrate, which AMD and Intel are doing in their factories. This includes imparting conductive properties to the substrate. The second stage is the test of substrates, assembly and packaging of the processor. The latter operation is usually performed in less expensive countries. If you look at Intel processors, you will find that the packaging was done in Costa Rica, Malaysia, the Philippines, etc.

AMD and Intel today are trying to produce products for the maximum number of market segments, and based on the smallest possible range of crystals. A perfect example is the processor line Intel Core 2 Duo. There are three processors here, codenamed for different markets: Merom for mobile applications, Conroe - desktop version, Woodcrest - server version. All three processors are built on the same technology base, which allows the manufacturer to make decisions in the last stages of production. Features can be enabled or disabled, and the current clock rate gives Intel an excellent chip yield. If the market demand for mobile processors has increased, Intel may focus on releasing Socket 479 models. If the demand for desktop models has increased, then the company will test, validate and package crystals for Socket 775, while server processors are packed for Socket 771. So even quad-core processors are being created: two dual-core crystals are installed in one package, so we get four cores.

How chips are made

Chip production involves the imposition of thin layers with a complex "pattern" on silicon substrates. First, an insulating layer is created that works like an electrical shutter. A photoresist material is then applied on top, and unwanted areas are removed using masks and high-intensity radiation. When the irradiated areas are removed, areas of silicon dioxide are exposed underneath, which is removed by etching. After that, the photoresist material is also removed, and we get a certain structure on the silicon surface. Then additional photolithography processes are carried out, with different materials, until the desired three-dimensional structure is obtained. Each layer can be doped with a certain substance or ions, changing the electrical properties. Windows are created in each layer in order to then bring metal connections.

As for the production of substrates, they must be cut into thin "pancakes" from a single single crystal-cylinder, so that later they can be easily cut into separate processor crystals. At each stage of production, complex testing is performed to assess the quality. Electrical probes are used to test each crystal on the substrate. Finally, the substrate is cut into individual cores, the non-working cores are immediately eliminated. Depending on the characteristics, the core becomes one or another processor and is wrapped in a package that makes it easier to install the processor on motherboard... All functional blocks go through intensive stress tests.

It all starts with substrates

The first step in manufacturing processors is done in a clean room. By the way, it is important to note that such a technological production represents the accumulation of huge capital per square meter. The construction of a modern plant with all the equipment can easily "fly away" 2-3 billion dollars, and it takes several months for test runs of new technologies. Only then can the plant mass-produce processors.

In general, the chip manufacturing process consists of several substrate processing steps. This includes creating the substrates themselves, which will eventually be cut into individual crystals.

It all starts with growing a single crystal, for which a seed crystal is embedded in a bath of molten silicon, which is located just above the melting point of polycrystalline silicon. It is important that the crystals grow slowly (about a day) to ensure that the atoms are in the correct arrangement. Polycrystalline or amorphous silicon is composed of many different crystals that will lead to unwanted surface structures with poor electrical properties. When the silicon is melted, it can be doped with other substances that change its electrical properties. The whole process takes place in a sealed room with a special air composition so that silicon does not oxidize.

The single crystal is cut into "pancakes" using a diamond hole saw, which is very precise and does not create large irregularities on the surface of the substrates. Of course, in this case, the surface of the substrates is still not perfectly flat, so additional operations are required.

First, using rotating steel plates and an abrasive material (such as aluminum oxide), a thick layer is removed from the substrates (a process called lapping). As a result, irregularities ranging from 0.05 mm to approximately 0.002 mm (2000 nm) are eliminated. Then round off the edges of each underlay as sharp edges can peel off layers. Further, the etching process is used, when using various chemicals (hydrofluoric acid, acetic acid, nitric acid) the surface is smoothed by about 50 microns. Physically, the surface does not deteriorate, since the whole process is completely chemical. It allows you to remove the remaining errors in the crystal structure, as a result of which the surface will be close to ideal.

The last step is polishing, which smoothes the surface to roughness, maximum 3 nm. Polishing is carried out using a mixture of sodium hydroxide and granular silicon dioxide.

Today, microprocessor substrates are either 200 mm or 300 mm in diameter, which allows chip manufacturers to obtain multiple processors from each. The next step will be 450mm substrates, but they shouldn't be expected until 2013. In general, the larger the diameter of the substrate, the more chips of the same size can be produced. A 300mm substrate, for example, provides more than twice the number of processors than a 200mm.

We have already mentioned the doping that occurs during the growth of the single crystal. But doping is done both with the finished substrate and later during photolithography processes. This allows you to change the electrical properties of certain areas and layers, and not the entire structure of the crystal.

The dopant can be added via diffusion. Dopant atoms fill free space inside the crystal lattice, between silicon structures. In some cases, the existing structure can also be alloyed. Diffusion is carried out using gases (nitrogen and argon) or using solids or other sources of dopant.

Another approach to doping is ion implantation, which is very useful in changing the properties of a substrate that has been doped, since ion implantation occurs at ordinary temperatures. Therefore, existing impurities do not diffuse. You can apply a mask to the substrate, which allows you to process only certain areas... Of course, one can talk about ion implantation for a long time and discuss the depth of penetration, activation of the additive at high temperatures, channel effects, penetration into oxide levels, etc., but this is beyond the scope of our article. The procedure can be repeated several times during production.

To create the regions of an integrated circuit, a photolithography process is used. Since it is not necessary to irradiate the entire surface of the substrate in this case, it is important to use so-called masks, which transmit high-intensity radiation only to certain areas. Masks can be compared to black and white negative. Integrated circuits have many layers (20 or more), and each layer requires its own mask.

A thin chrome film structure is applied to the surface of a quartz glass plate to create a pattern. At the same time, expensive instruments using an electron flow or a laser prescribe the necessary data of an integrated circuit, as a result of which we get a template from chromium on the surface of a quartz substrate. It is important to understand that each modification of the integrated circuit leads to the need to produce new masks, so the whole process of making edits is very costly. For very complex schemes, masks take a long time to create.

With the help of photolithography, a structure is formed on a silicon substrate. The process is repeated several times until many layers (more than 20) are created. Layers can consist of different materials, moreover, you also need to think over the connections with microscopic wires. All layers can be alloyed.

Before the photolithography process begins, the substrate is cleaned and heated to remove sticky particles and water. Then the substrate is coated with silicon dioxide using a special device. Next, a bonding agent is applied to the substrate to ensure that the photoresist material to be applied in the next step remains on the substrate. The photoresist material is applied to the middle of the substrate, which then begins to rotate at a high speed so that the layer is evenly distributed over the entire surface of the substrate. The substrate is then heated again.

Then, through a mask, the cover is irradiated with a quantum laser, hard ultraviolet radiation, X-rays, beams of electrons or ions - all of these sources of light or energy can be used. Electron beams are mainly used to create masks, X-rays and ion beams for research purposes, and industrial production today is dominated by hard UV radiation and gas lasers.

Hard UV light with a wavelength of 13.5 nm irradiates the photoresist material while passing through the mask.

Projection time and focus are very important to obtain the desired result. Poor focusing will leave extra particles of photoresist material as some of the holes in the mask will not be properly irradiated. The same will happen if the projection time is too short. Then the structure of the photoresist material will be too wide, the areas under the holes will be underexposed. On the other hand, excessive projection times create too large areas under the holes and too narrow a photoresist material structure. It is usually very time consuming and difficult to adjust and optimize the process. An unsuccessful adjustment will lead to serious deviations in the connecting conductors.

A special stepping projection device moves the substrate to the desired position. Then a line or one section can be projected, most often corresponding to one processor die. Additional micro-installations can make additional changes. They can debug existing technology and optimize the workflow. Micro-installations typically operate on areas of less than 1 sq. mm, while conventional installations cover larger areas.

The substrate then proceeds to a new stage, where the weakened photoresist material is removed, allowing access to the silicon dioxide. There are wet and dry etching processes that treat areas of silicon dioxide. Wet processes use chemical compounds, and dry processes use gas. A separate process is the removal of the residues of the photoresist material. Manufacturers often combine wet and dry removal so that the photoresist material is completely removed. This is important because the photoresist material is organic and, if not removed, can lead to defects on the substrate. After etching and cleaning, you can proceed to inspect the substrate, which usually happens at each important stage, or transfer the substrate to a new photolithography cycle.

Substrate test, assembly, packaging

The finished substrates are tested in so-called probe installations. They work with the entire substrate. Probe contacts are superimposed on the contacts of each crystal, which allows electrical tests. Through software all functions of each core are tested.

By cutting, individual cores can be obtained from the substrate. At the moment, the probe control installations have already revealed which crystals contain errors, therefore, after cutting, they can be separated from the good ones. Previously, damaged crystals were physically marked, now there is no need for this, all information is stored in a single database.

Crystal mount

The functional core then needs to be bonded to the processor packaging using an adhesive.

Then you need to make wire connections connecting the contacts or legs of the package and the crystal itself. Gold, aluminum or copper connections can be used.

Most modern processors use plastic wrap with a heat spreader.

Typically, the core is wrapped in ceramic or plastic to prevent damage. Modern processors equipped with a so-called heat spreader, which provides additional protection for the crystal, as well as a large contact surface with the cooler.

CPU Testing

The last stage involves testing the processor, what happens at elevated temperatures, in accordance with the processor specifications. The processor is automatically installed into the test socket, after which all the necessary functions are analyzed.

How microcircuits are made

to understand what is the main difference between these two technologies, it is necessary to take a short excursion into the very technology of production of modern processors or integrated circuits.

As you know from the school physics course, in modern electronics, the main components of integrated circuits are p-type and n-type semiconductors (depending on the type of conductivity). A semiconductor is a substance that surpasses dielectrics in conductivity, but is inferior to metals. Both types of semiconductors can be based on silicon (Si), which in its pure form (the so-called intrinsic semiconductor) does not conduct electric current well, but the addition (introduction) of a certain impurity into silicon makes it possible to radically change its conducting properties. There are two types of impurities: donor and acceptor. A donor impurity leads to the formation of n-type semiconductors with an electronic type of conductivity, and an acceptor impurity leads to the formation of p-type semiconductors with a hole type of conductivity. Contacts of p- and n-semiconductors make it possible to form transistors - the main structural elements of modern microcircuits. These transistors, called CMOS transistors, can be in two basic states: open, when they conduct electricity, and locked, when they do not conduct electricity. Since CMOS transistors are the main elements of modern microcircuits, let's talk about them in more detail.

How a CMOS transistor works

The simplest n-type CMOS transistor has three electrodes: source, gate, and drain. The transistor itself is made in a p-type semiconductor with hole conductivity, and n-type semiconductors with electronic conductivity are formed in the drain and source regions. Naturally, due to the diffusion of holes from the p-region to the n-region and the reverse diffusion of electrons from the n-region to the p-region, depleted layers (layers in which the majority charge carriers are absent) are formed at the boundaries of the transitions of the p- and n-regions. In the normal state, that is, when no voltage is applied to the gate, the transistor is in a "locked" state, that is, it is not able to conduct current from the source to the drain. The situation does not change, even if we apply a voltage between the drain and the source (in this case, we do not take into account the leakage currents caused by the movement under the influence of the generated electric fields of minority charge carriers, that is, holes for the n-region and electrons for the p-region).

However, if a positive potential is applied to the gate (Fig. 1), then the situation will change radically. Under the influence of the electric field of the gate, holes are pushed deep into the p-semiconductor, and electrons, on the contrary, are drawn into the region under the gate, forming an electron-enriched channel between the source and drain. If a positive voltage is applied to the gate, these electrons begin to move from source to drain. In this case, the transistor conducts current - they say that the transistor "opens". If the voltage is removed from the gate, electrons stop being drawn into the region between the source and drain, the conducting channel is destroyed and the transistor stops passing current, that is, it is "locked". Thus, by changing the voltage at the gate, you can open or turn off the transistor, in the same way as you can turn on or off a conventional toggle switch by controlling the passage of current through the circuit. This is why transistors are sometimes called electronic switches. However, unlike conventional mechanical switches, CMOS transistors are virtually inertia-free and are capable of going from open to locked state trillions of times per second! It is this characteristic, that is, the ability of instantaneous switching, that ultimately determines the speed of the processor, which consists of tens of millions of such simplest transistors.

So, a modern integrated circuit consists of tens of millions of the simplest CMOS transistors. Let us dwell in more detail on the process of manufacturing microcircuits, the first stage of which is the production of silicon substrates.

Step 1. Growing blanks

The creation of such substrates begins with the growth of a cylindrical silicon single crystal. These single crystal billets are then cut into wafers approximately 1/40 "thick and 200 mm (8") or 300 mm (12 ") in diameter. These are the silicon substrates used for the production of microcircuits.

When forming wafers from silicon single crystals, the fact that for ideal crystal structures the physical properties largely depend on the chosen direction (anisotropy property) is taken into account. For example, the resistance of a silicon substrate will be different in the longitudinal and transverse directions. Similarly, depending on the orientation of the crystal lattice, a silicon crystal will react differently to any external influences associated with its further processing (for example, etching, sputtering, etc.). Therefore, the plate should be cut from the single crystal in such a way that the orientation of the crystal lattice relative to the surface is strictly maintained in a certain direction.

As already noted, the diameter of the silicon single crystal preform is either 200 or 300 mm. Moreover, the diameter of 300 mm is a relatively new technology, which we will discuss below. It is clear that a plate of this diameter can accommodate far more than one microcircuit, even if we are talking about an Intel Pentium 4 processor. Indeed, several dozen microcircuits (processors) are formed on one such plate-substrate, but for simplicity we will consider only the processes occurring on a small area of \u200b\u200bone future microprocessor.

Step 2. Applying a protective dielectric film (SiO2)

After the formation of the silicon substrate, the stage of creating the most complex semiconductor structure begins.

For this, the so-called donor and acceptor impurities must be introduced into silicon. However, the question arises - how to implement the introduction of impurities according to a precisely given pattern-pattern? To make this possible, those areas where it is not required to incorporate impurities are protected with a special silicon dioxide film, leaving only those areas exposed that are subjected to further processing (Fig. 2). The process of forming such a protective film of the desired pattern consists of several stages.

In the first stage, the entire silicon wafer is completely covered with a thin film of silicon dioxide (SiO2), which is a very good insulator and acts as a protective film during further processing of the silicon crystal. The wafers are placed in a chamber where, at high temperature (from 900 to 1100 ° C) and pressure, oxygen diffuses into the surface layers of the wafer, leading to the oxidation of silicon and to the formation of a surface film of silicon dioxide. In order for the silicon dioxide film to have a precisely specified thickness and not contain defects, it is necessary to strictly maintain a constant temperature at all points of the wafer during the oxidation process. If not the entire wafer is to be covered with a silicon dioxide film, then a Si3N4 mask is first applied to the silicon substrate to prevent unwanted oxidation.

Step 3. Applying the photoresist

After the silicon substrate is covered with a protective film of silicon dioxide, it is necessary to remove this film from those places that will be subjected to further processing. The film is removed by etching, and to protect the remaining areas from etching, a layer of so-called photoresist is applied to the surface of the wafer. The term "photoresists" denotes compositions that are light-sensitive and resistant to aggressive factors. The applied compositions should have, on the one hand, certain photographic properties (under the influence of ultraviolet light, they become soluble and washed out during the etching process), and on the other hand, resistive, allowing them to withstand etching in acids and alkalis, heating, etc. The main purpose of photoresists is to create a protective relief of the desired configuration.

The process of applying a photoresist and its further irradiation with ultraviolet light according to a given pattern is called photolithography and includes the following basic operations: the formation of a photoresist layer (processing of the substrate, application, drying), the formation of a protective relief (exposure, development, drying) and transfer of the image to the substrate (etching, sputtering etc.).

Before applying the photoresist layer (Fig. 3) to the substrate, the latter is pretreated, as a result of which its adhesion to the photoresist layer is improved. A centrifugation method is used to apply a uniform layer of photoresist. The substrate is placed on a rotating disk (centrifuge), and under the influence of centrifugal forces the photoresist is distributed over the surface of the substrate in an almost uniform layer. (Speaking of a practically uniform layer, one should take into account the fact that, under the action of centrifugal forces, the thickness of the resulting film increases from the center to the edges; however, this method of applying a photoresist makes it possible to withstand variations in the layer thickness within ± 10%.)

Step 4. Lithography

After the application and drying of the photoresist layer, the stage of formation of the necessary protective relief begins. The relief is formed as a result of the fact that under the action of ultraviolet radiation falling on certain areas of the photoresist layer, the latter changes the properties of solubility, for example, the illuminated areas stop dissolving in the solvent, which remove areas of the layer that were not exposed to light, or vice versa - the illuminated areas dissolve. By the method of forming the relief, photoresists are divided into negative and positive. Negative photoresists under the influence of ultraviolet radiation form protective areas of the relief. On the other hand, positive photoresists, under the influence of ultraviolet radiation, acquire properties of flow and are washed out by the solvent. Accordingly, a protective layer is formed in areas that are not exposed to ultraviolet radiation.

To illuminate the desired areas of the photoresist layer, a special mask template is used. Most often, optical glass plates with opaque elements obtained by photographic or otherwise are used for this purpose. In fact, such a template contains a drawing of one of the layers of the future microcircuit (there can be several hundred such layers in total). Since this template is a reference, it must be executed with great precision. In addition, taking into account the fact that a lot of photographic plates will be made for one photomask, it must be durable and resistant to damage. Hence, it is clear that a photomask is a very expensive thing: depending on the complexity of the microcircuit, it can cost tens of thousands of dollars.

Ultraviolet radiation, passing through such a template (Fig. 4), illuminates only the required areas of the surface of the photoresist layer. After irradiation, the photoresist undergoes development, which removes unnecessary portions of the layer. This opens the corresponding part of the silicon dioxide layer.

Despite the seeming simplicity of the photolithographic process, it is this stage of microcircuit production that is the most difficult. The fact is that, in accordance with Moore's prediction, the number of transistors on a single microcircuit increases exponentially (doubles every two years). Such an increase in the number of transistors is possible only due to a decrease in their size, but it is precisely the decrease that "rests" on the lithography process. In order to make the transistors smaller, it is necessary to reduce the geometric dimensions of the lines applied to the photoresist layer. But there is a limit to everything - it is not so easy to focus a laser beam on a point. The fact is that, in accordance with the laws of wave optics, the minimum spot size into which a laser beam is focused (in fact, it is not just a spot, but a diffraction pattern) is determined, among other factors, by the length of the light wave. The development of lithographic technology since its invention in the early 70s has been in the direction of shrinking the wavelength of light. This is what made it possible to reduce the size of the integrated circuit elements. Since the mid-1980s, photolithography has begun to use ultraviolet radiation produced by a laser. The idea is simple: the wavelength of ultraviolet radiation is shorter than the wavelength of visible light, therefore it is possible to obtain thinner lines on the surface of the photoresist. Until recently, lithography used deep ultraviolet radiation (Deep Ultra Violet, DUV) with a wavelength of 248 nm. However, when photolithography crossed the 200 nm boundary, serious problems arose, which for the first time cast doubt on the possibility of further use of this technology. For example, at wavelengths less than 200 microns, too much light is absorbed by the light-sensitive layer, so the process of transferring the circuit pattern to the processor becomes more complicated and slower. Challenges like these are prompting researchers and manufacturers to seek alternatives to traditional lithographic technology.

A new lithographic technology called EUV lithography (Extreme UltraViolet) is based on the use of ultraviolet radiation with a wavelength of 13 nm.

The transition from DUV to EUV lithography provides more than a 10-fold decrease in the wavelength and a transition to the range where it is comparable to the size of only a few tens of atoms.

The currently used lithographic technology allows the application of a template with a minimum conductor width of 100 nm, while EUV lithography makes it possible to print lines of much smaller width - up to 30 nm. Controlling ultrashort radiation is not as easy as it sounds. Since EUV radiation is well absorbed by glass, the new technology involves the use of a series of four special convex mirrors, which reduce and focus the image obtained after applying the mask (Fig. 5,,). Each such mirror contains 80 separate metal layers approximately 12 atoms thick.

Step 5. Etching

After exposure of the photoresist layer, the etching stage begins in order to remove the silicon dioxide film (Fig. 8).

The pickling process is often associated with acid baths. This acid etching method is familiar to radio amateurs who made printed circuit boards themselves. To do this, a pattern of the tracks of the future board is applied to the foil textolite with varnish, which serves as a protective layer, and then the plate is lowered into a bath with nitric acid. Unnecessary foil areas are etched away, revealing pure textolite. This method has a number of disadvantages, the main one being the inability to accurately control the layer removal process, since too many factors affect the etching process: acid concentration, temperature, convection, etc. In addition, the acid interacts with the material in all directions and gradually penetrates under the edge of the photoresist mask, that is, destroys the layers covered with the photoresist from the side. Therefore, in the manufacture of processors, a dry etching method is used, also called plasma. This method allows you to accurately control the etching process, and the destruction of the etched layer occurs strictly in the vertical direction.

Dry etching uses an ionized gas (plasma) to remove silicon dioxide from the wafer surface, which reacts with the silicon dioxide surface to form volatile by-products.

After the etching procedure, that is, when the required areas of pure silicon are exposed, the rest of the photo layer is removed. Thus, a silicon dioxide pattern remains on the silicon substrate.

Step 6. Diffusion (ion implantation)

Recall that the previous process of forming the required pattern on a silicon substrate was required in order to create semiconductor structures in the right places by introducing a donor or acceptor impurity. The process of impurity introduction is carried out by means of diffusion (Fig. 9) - uniform introduction of impurity atoms into the silicon crystal lattice. Antimony, arsenic or phosphorus are usually used to obtain an n-type semiconductor. To obtain a p-type semiconductor, boron, gallium or aluminum is used as an impurity.

For the diffusion process of the dopant, ion implantation is used. The implantation process consists in the fact that the ions of the required impurity are "fired" from the high-voltage accelerator and, having sufficient energy, penetrate into the surface layers of silicon.

So, at the end of the stage of ion implantation, the required layer of the semiconductor structure has been created. However, microprocessors can have several such layers. To create the next layer in the resulting diagram, an additional thin layer of silicon dioxide is grown. After that, a layer of polycrystalline silicon and another layer of photoresist are applied. Ultraviolet light is passed through the second mask and highlights the corresponding pattern on the photo layer. This is followed by the steps of dissolution of the photo layer, etching, and ion implantation.

Step 7. Spraying and deposition

The imposition of new layers is carried out several times, while for the interlayer connections in the layers "windows" are left, which are filled with metal atoms; as a result, metal stripes are created on the crystal - conductive regions. Thus, in modern processors, connections are established between layers that form a complex three-dimensional scheme. The process of growing and processing all layers takes several weeks, and the production cycle itself consists of more than 300 stages. As a result, hundreds of identical processors are formed on the silicon wafer.

In order to withstand the stresses that the wafers are subjected to during the layer deposition process, silicon substrates are initially made thick enough. Therefore, before cutting the wafer into separate processors, its thickness is reduced by 33% and contamination from the back side is removed. Then a layer of a special material is applied to the back side of the substrate, which improves the attachment of the crystal to the case of the future processor.

Step 8. Final stage

At the end of the formation cycle, all processors are thoroughly tested. Then concrete, already tested crystals are cut out of the substrate plate using a special device (Fig. 10).

Each microprocessor is embedded in a protective case, which also provides electrical connection of the microprocessor crystal to external devices. The type of enclosure depends on the type and intended use of the microprocessor.

After being sealed into the housing, each microprocessor is re-tested. Defective processors are rejected, and serviceable ones are subjected to stress tests. The processors are then sorted according to their behavior at different clock speeds and supply voltages.

Advanced technologies

The technological process of manufacturing microcircuits (in particular, processors) is considered by us in a very simplified way. But even this superficial presentation allows us to understand the technological difficulties that one has to face when reducing the size of transistors.

However, before considering new promising technologies, let us answer the question posed at the very beginning of the article: what is the design standard of the technological process and how does the design standard of 130 nm differ from the standard of 180 nm? 130 nm or 180 nm is the characteristic minimum distance between two neighboring elements in one layer of the microcircuit, that is, a kind of grid step to which the elements of the microcircuit are bound. In this case, it is quite obvious that the smaller this characteristic size, the more transistors can be placed on the same area of \u200b\u200bthe microcircuit.

Currently, Intel processors use a 0.13 micron manufacturing process. This technology is used to manufacture the Intel Pentium 4 processor with the Northwood core, the Intel Pentium III processor with the Tualatin core and the Intel Celeron processor. In the case of using such a technological process, the effective channel width of the transistor is 60 nm, and the thickness of the gate oxide layer does not exceed 1.5 nm. In total, the Intel Pentium 4 processor houses 55 million transistors.

Along with the increase in the density of transistors in the processor crystal, the 0.13-micron technology, which replaced the 0.18-micron technology, has other innovations. First, it uses copper connections between the individual transistors (in 0.18 micron technology, the connections were aluminum). Secondly, 0.13 micron technology provides more low power consumption... For mobile technology, for example, this means that the power consumption of microprocessors becomes less, and the operating time from battery - more.

Well, the last innovation that was implemented in the transition to the 0.13-micron technological process is the use of silicon wafers (wafer) with a diameter of 300 mm. Recall that before that, most processors and microcircuits were made on the basis of 200 mm wafers.

Increasing the diameter of the platters allows you to reduce the cost of each processor and increase the output of good quality products. Indeed, the area of \u200b\u200ba plate with a diameter of 300 mm is 2.25 times larger than the area of \u200b\u200ba plate with a diameter of 200 mm, respectively, and the number of processors obtained from one plate with a diameter of 300 mm is more than two times larger.

In 2003, it is expected to introduce a new technological process with an even lower design standard, namely the 90-nanometer one. The new manufacturing process, which Intel will use to manufacture most of its products, including processors, chipsets, and communications equipment, was developed at Intel's 300mm wafer D1C pilot plant in Hillsboro, Oregon.

On October 23, 2002, Intel announced the opening of a new $ 2 billion facility in Rio Rancho, New Mexico. The new plant, dubbed F11X, will use modern technology, which will be used to manufacture processors on 300 mm substrates using a 0.13 micron design rate process. In 2003 the plant will be transferred to a technological process with a design standard of 90 nm.

In addition, Intel has already announced the resumption of construction at Fab 24 in Lakeslip, Ireland, which will manufacture semiconductor components on 300mm silicon wafers with a 90nm design rule. The new enterprise with a total area of \u200b\u200bover 1 million sq. M. ft. with ultra clean rooms of 160 thousand sq. ft. is expected to be operational in the first half of 2004 and will employ over a thousand employees. The project cost is about $ 2 billion.

The 90nm process applies whole line advanced technologies... It is also the world's smallest commercially available CMOS transistors with a gate length of 50 nm (Fig. 11), which provides increased performance while reducing power consumption, and the thinnest gate oxide layer of any transistor ever produced - just 1.2 nm (Fig. 12), or less than 5 atomic layers, and the industry's first implementation of high performance strained silicon technology.

Of the listed characteristics, perhaps only the concept of “strained silicon” needs commentary (Fig. 13). In such silicon, the distance between atoms is greater than in an ordinary semiconductor. This, in turn, provides a freer flow of current, similar to how vehicles move more freely and faster on a road with wider traffic lanes.

As a result of all the innovations, the performance of transistors is improved by 10-20%, with an increase in production costs by only 2%.

In addition, the 90nm process uses seven layers per chip (Figure 14), one more layer than the 130nm process, and copper connections.

All of these features, combined with 300mm silicon wafers, provide Intel with gains in performance, production and cost. Consumers also benefit as Intel's new technology process continues to drive the industry forward in line with Moore's Law, while improving processor performance time and again.

Modern microprocessors are the fastest and smartest microcircuits in the world. They can perform up to 4 billion operations per second and are produced using many different technologies. Since the early 90s of the 20th century, when processors went into mass use, they have gone through several stages of development. The apogee of the development of microprocessor structures using the existing technologies of 6th generation microprocessors was 2002, when it became available to use all the basic properties of silicon to obtain high frequencies with the least losses in production and creation of logic circuits. Now, the efficiency of new processors is falling somewhat despite the constant increase in the frequency of operation of crystals, since silicon technologies are approaching the limit of their capabilities.

Microprocessor is an integrated circuit formed on a small silicon crystal. Silicon is used in microcircuits due to the fact that it has semiconducting properties: its electrical conductivity is higher than that of dielectrics, but less than that of metals. Silicon can be made both as an insulator that prevents the movement of electric charges, and as a conductor - then electric charges will freely pass through it. The conductivity of a semiconductor can be controlled by introducing impurities.

The microprocessor contains millions of transistors, interconnected by the thinnest conductors of aluminum or copper, and used for data processing. This is how the internal tires are formed. As a result, the microprocessor performs many functions - from mathematical and logical operations to controlling the operation of other microcircuits and the entire computer.

One of the main parameters of the microprocessor is the crystal frequency, which determines the number of operations per unit of time, the frequency of the system bus, the amount of internal cache memory.SRAM ... The processor is marked by the frequency of the crystal. The frequency of the crystal is determined by the switching frequency of the transistors from the closed state to the open state. The ability of a transistor to switch faster is determined by the technology used to manufacture the silicon wafers from which the chips are made. The dimension of the technological process determines the size of the transistor (its thickness and gate length). For example, using the 90nm process technology, which was introduced in early 2004, the transistor size is 90nm and the gate length is 50nm.

All modern processors use field effect transistors. The transition to a new technical process allows you to create transistors with a higher switching frequency, lower leakage currents, and smaller sizes. Downsizing allows you to simultaneously reduce die area, and hence heat dissipation, and a thinner gate allows you to apply less voltage for switching, which also reduces power consumption and heat dissipation.

The technological norm of 90 nm turned out to be a rather serious technological barrier for many chip manufacturers. This is confirmed by the companyTSMC , which produces chips for many market giants such as companiesAMD, nVidia, ATI, VIA ... For a long time, she was unable to establish the production of chips using 0.09 micron technology, which led to a low yield of suitable crystals. This is one of the reasons whyAMD for a long time postponed the release of its processors with technologySOI (Silicon - on - Insulator ). This is due to the fact that it is on this dimension of the elements that all kinds of previously not so strongly perceptible negative factors such as leakage currents, a large scatter of parameters and an exponential increase in heat release began to manifest themselves strongly.

There are two leakage currents: gate leakage current and subthreshold leakage. The first caused by the spontaneous movement of electrons between the silicon substrate of the channel and the polysilicon gate. The second - spontaneous movement of electrons from the source of the transistor to the drain. Both of these effects lead to the fact that you have to raise the supply voltage to control the currents in the transistor, which negatively affects the heat generation. So, by reducing the size of the transistor, first of all, its gate and the silicon dioxide layer (SiO 2 ), which is a natural barrier between the gate and the channel.

On the one hand, this improves the speed characteristics of the transistor (switching time), but on the other hand, it increases the leakage. That is, a kind of closed cycle turns out. So the transition to 90 nm is another decrease in the thickness of the dioxide layer, and at the same time an increase in leaks. The fight against leaks is, again, an increase in control voltages, and, accordingly, a significant increase in heat generation. All this led to a delay in the introduction of a new technical process on the part of competitors in the microprocessor market -Intel and AMD.

One of the alternative solutions is the use of technologySOI (silicon on insulator), which was recently introduced by the companyAMD in their 64-bit processors. However, it cost her a lot of effort and overcoming a large number of associated difficulties. But the technology itself provides a huge number of advantages with a relatively small number of disadvantages.

The essence of the technology, in general, is quite logical - the transistor is separated from the silicon substrate by another thin layer of insulator. There are lots of pluses. No uncontrolled movement of electrons under the channel of the transistor, affecting its electrical characteristics - times. After supplying the unlocking current to the gate, the time of channel ionization to the operating state, until the moment when the operating current flows through it, is reduced, that is, the second key parameter of the transistor performance improves, the time of its on / off is two. Or, at the same speed, you can simply lower the unlocking current - three. Or find some kind of compromise between increasing the speed of work and decreasing the voltage. While maintaining the same unlocking current, the increase in transistor performance can be up to 30%, if you leave the frequency the same, focusing on energy saving, then the plus can be large - up to 50%.

Finally, the characteristics of the channel become more predictable, and the transistor itself becomes more resistant to sporadic errors, such as those caused by cosmic particles, falling into the channel substrate and unexpectedly ionizing it. Now, getting into the substrate located under the insulator layer, they have no effect on the operation of the transistor. The only drawback of SOI is that it is necessary to reduce the depth of the emitter / collector region, which directly and directly affects the increase in its resistance as the thickness decreases.

Finally, third the reason that contributed to the slowdown in frequency growth is the low activity of competitors in the market. We can say that everyone was busy with their own affairs.AMD was engaged in the widespread introduction of 64-bit processors, forIntel it was a period of improving a new technical process, debugging for an increased yield of suitable crystals.

So, the need to switch to new technical processes is obvious, but technologists are given this every time more and more with great difficulty. First microprocessorsPentium (1993) were produced according to the technological process 0.8 microns, then 0.6 microns. In 1995, for the first time for 6th generation processors, the 0.35 micron process technology was applied. In 1997, it changed to 0.25 microns, and in 1999 - to 0.18 microns. Modern processors are made using 0.13 and 0.09 micron technologies, the latter being introduced in 2004. As you can see, for these technical processes, Moore's law is observed, which states that every two years the frequency of crystals doubles with an increase in the number of transistors from them. The technical process is changing at the same pace. True, in the future the "frequency race" will outpace this law. By 2006 the companyIntel plans to master the 65-nm process technology, and in 2009 - 32-nm.

Here it is time to recall the structure of the transistor, namely, a thin layer of silicon dioxide, an insulator located between the gate and the channel, and performing an understandable function - a barrier for electrons, preventing leakage of the gate current.

Obviously, the thicker this layer, the better it performs its insulating functions, but it is an integral part of the channel, and it is no less obvious that if we are going to reduce the length of the channel (the size of the transistor), then we need to reduce its thickness. at a fast pace. By the way, over the past several decades, the thickness of this layer is on average about 1/45 of the entire length of the channel. But this process has its end - as Intel claimed five years ago, if SiO2 continues to be used, as it has been over the past 30 years, the minimum layer thickness will be 2.3 nm, otherwise the leakage current of the gate current will simply acquire unrealistic values ...

Until recently, nothing was done to reduce the sub-channel leakage, now the situation is starting to change, since the operating current, along with the gate response time, is one of the two main parameters characterizing the speed of the transistor, and the leakage in the off state directly affects it - to save the required efficiency of the transistor, it is necessary, accordingly, to raise the operating current, with all the ensuing conditions.

Manufacturing microprocessor is a complex process that includes more than 300 stages. Microprocessors are formed on the surface of thin circular silicon wafers - substrates, as a result of a certain sequence of different processing processes using chemicals, gases and ultraviolet radiation.

Substrates are usually 200 millimeters, or 8 inches in diameter. However, Intel has already switched to 300 mm or 12-inch wafers. New plates allow you to get almost 4 times more crystals, and the yield is much higher. The wafers are made from silicon, which is refined, melted and grown into long cylindrical crystals. The crystals are then cut into thin plates and polished until their surfaces are mirror-smooth and free from defects. Then, sequentially repeating cyclically, thermal oxidation is performed (formation of a filmSiO 2 ), photolithography, impurity diffusion (phosphorus), epitaxy (layer growth).

In the process of manufacturing microcircuits, the thinnest layers of materials are applied to the blank plates in the form of carefully calculated patterns. One plate can accommodate up to several hundred microprocessors, the manufacture of which requires more than 300 operations. The entire process of manufacturing processors can be divided into several stages: growing silicon dioxide and creating conductive regions, testing, manufacturing of the case and delivery.

The microprocessor manufacturing process begins with " cultivation "on the surface of a polished plate of an insulating layer of silicon dioxide. This step is carried out in an electric furnace at a very high temperature. The thickness of the oxide layer depends on the temperature and time that the plate spends in the furnace.

Then follows photolithography - a process during which a diagram is formed on the surface of the plate. First, a temporary layer of a photosensitive material is applied to the plate - a photoresist, onto which an image of transparent areas of the template, or photomask is projected using ultraviolet radiation. Masks are made during the design of the processor and are used to generate circuit patterns in each layer of the processor. Under the influence of radiation, the illuminated areas of the photolayer become soluble, and they are removed using a solvent (hydrofluoric acid), revealing the silicon dioxide underneath.

The exposed silica is removed by a process called " etching ". Then the remaining photolayer is removed, as a result of which a pattern of silicon dioxide remains on the semiconductor wafer. As a result of a series of additional photolithography and etching operations, polycrystalline silicon with the properties of a conductor is also deposited on the wafer.

During the next operation, called " alloying ", the open areas of the silicon wafer are bombarded with ions of various chemical elements, which form negative and positive charges in silicon, which change the electrical conductivity of these areas.

Overlay new layers with the subsequent etching of the circuit is carried out several times, while for the interlayer connections in the layers, "windows" are left, which are filled with metal, forming electrical connections between the layers. Intel used copper conductors for its 0.13 micron manufacturing process. In the 0.18 micron manufacturing process and previous processes generations of Intel used aluminum. Both copper and aluminum are excellent conductors of electricity. When using the 0.18-micron technical process, 6 layers were used, when introducing the 90 nm technical process in 2004, 7 layers of silicon were used.

Each layer of the processor has its own pattern, together all these layers form a three-dimensional electronic circuit. The application of layers is repeated 20 - 25 times over several weeks.

In order to withstand the stresses to which the substrates are subjected during the deposition process, the silicon wafers must be initially thick enough. Therefore, before cutting the plate into separate microprocessors, its thickness is reduced by 33% using special processes and contaminants are removed from the back side. Then a layer of a special material is applied to the reverse side of the "thinned" plate, which improves the subsequent fastening of the crystal to the case. In addition, this layer provides electrical contact between the back surface of the integrated circuit and the package after assembly.

After that, the plates are tested to check the quality of all machining operations. Individual components are tested to determine if processors are working properly. If faults are detected, the data is analyzed to understand at what stage of processing the failure occurred.

Then, electrical probes are connected to each processor and power is supplied. Processors are tested by a computer, which determines whether the manufactured processors meet specified specifications.

After testing, the wafers are sent to an assembly shop where they are cut into small rectangles, each containing an integrated circuit. A special precision saw is used to separate the plate. Non-working crystals are discarded.

Then each crystal is placed in an individual case. The case protects the crystal from external influences and provides its electrical connection to the board on which it will be subsequently installed. Tiny balls of solder, located at specific points on the crystal, are soldered to the electrical leads of the package. Now electrical signals can go from board to chip and vice versa.

In future processors, the companyIntel apply technologyBBUL , which will allow you to create fundamentally new cases with less heat generation and capacity between the legsCPU.

After installing the crystal in the package, the processor is tested again to determine if it is operational. Defective processors are discarded, and serviceable processors are subjected to stress tests: exposure to various temperature and humidity conditions, as well as electrostatic discharges. After each stress test, the processor is tested to determine its functional state. The processors are then sorted according to their behavior at different clock speeds and supply voltages.

The processors that have passed the tests go to the final inspection, the task of which is to confirm that the results of all previous tests were correct, and the parameters of the integrated circuit meet the established standards or even exceed them. All processors that pass final inspection are labeled and packaged for delivery to customers.

CPU it is the heart of any modern computer. Any microprocessor is essentially a large integrated circuit that houses transistors. By passing electrical current, transistors allow you to create binary logic (on - off) calculations. Modern processors are based on 45 nm technology. 45nm (nanometer) is the size of one transistor located on the processor plate. Until recently, 90 nm technology was mainly used.

The plates are made of silicon, which is the 2nd largest deposit in the earth's crust.

Silicon is obtained by chemical treatment, purifying it from impurities. After that, they begin to melt it, forming a silicon cylinder with a diameter of 300 millimeters. This cylinder is then cut into plates with a diamond thread. Each plate is about 1 mm thick. In order for the plate to have an ideal surface, after cutting with a thread, it is ground with a special grinder.

After that, the surface of the silicon wafer is perfectly flat. By the way, many manufacturing companies have already announced the possibility of working with 450 mm plates. The larger the surface, the more transistors to accommodate, and the higher the processor performance.

CPU consists of a silicon wafer, on the surface of which there are up to nine levels of transistors, separated by oxide layers, for insulation.

Processor technology development

Gordon Moore, one of the founders of Intel, one of the leaders in the production of processors in the world, in 1965, based on his observations, discovered the law according to which new models of processors and microcircuits appeared at equal intervals of time. The growth in the number of transistors in processors is growing by about 2 times in 2 years. For 40 years, Gordon Moore's Law has been working without distortion. The development of future technologies is just around the corner - there are already working prototypes based on 32nm and 22nm processor technology. Until mid-2004, processor power depended primarily on the processor frequency, but since 2005, the processor frequency has practically stopped growing. A new technology of multi-core processor has appeared. That is, several processor cores are created with an equal clock frequency, and during operation, the power of the cores is summed up. This increases the overall processor power.

Below you can watch a video about processor manufacturing.

This may seem like a silly question that can be answered in one sentence: Silicon is element 14 on the periodic table. Nonetheless, silicon is the most commonly cited element on electronics websites because it is not only the main component of most building materials, but also the basis for modern computer processors, and even the most likely candidate for the basic element of "carbon-free life" What makes silicon special?

Silicon as a building material

After oxygen, silicon is the most abundant element in the earth's crust, but it is not so easy to find it, because it is almost never found in its pure form. The most common occurrences in nature are silicate SiO4 or silicon dioxide SiO2. Silicon is also the main component of sand. Feldspar, granite, quartz are all based on the combination of silicon and oxygen.

Silicon compounds have a wide range of useful properties, mainly because they can bind other atoms very tightly in complex structures. Various silicates such as calcium silicate are the main component of cement, the main binder of concrete and even plaster. Some silicate materials are used in ceramics, and of course glass. In addition, silicon is added to substances such as cast iron to make the alloy more durable.
And, yes, silicon is also the main structural component of synthetic silicone material, which is why silicone is often confused with silicon. A famous example is Silicon Valley, which is actually silicon.

Silicon as a computer chip

When choosing a material for the base of computer transistors, resistance was a key factor. Conductors have low resistance and conduct current very easily, while insulators block current due to high resistance... A transistor must combine both properties.
Silicon isn't the only semiconductor on Earth - it's not even the best semiconductor. However, it is widely available. It's not hard to mine and easy to work with. And most importantly, scientists have found a reliable way to remove ordered crystals from it. These crystals are to silicon what a diamond is to a diamond.

Building perfect crystals is one of the main aspects of computer chip manufacturing. These crystals are then cut into thin wafers, engraved, processed, and hundreds of treatments before they become commercial processors. It is realistic to make more advanced transistors from carbon or such exotic materials as germanium, but none of them will allow such a large-scale production to be recreated - at least not yet.
Silicon crystals are currently being created in 300mm cylinders, but research is rapidly approaching the 450mm mark. This should cut production costs, but maintain the growth rate. What then? We'll likely finally have to ditch silicon in favor of a more advanced material - good news for progress, but almost certainly bad news for your wallet.

Silicon as extraterrestrial life

The phrase "carbon life" is mentioned quite often, but what does it mean? This means that the basic structural molecules of our body (proteins, amino acids, nucleic acids, fatty acids, etc.) are built on the basis of carbon atoms. This is because carbon can be tetravalent. Oxygen can form two stable chemical bonds at the same time, nitrogen only three, but carbon can hold up to four different atoms at once. It is a powerful foundation for building molecules and developing life.

Since the periodic table is ordered so that the elements in the vertical column have similar chemical properties - and right under the carbon is silicon. This is why so many theorists pay attention to "silicon life", one of the arguments in their favor is the fact that silicon is also tetravalent.
Of course, given that there is so much more silicon on Earth than carbon, there must be a good reason why organic life is carbon-based. And here you need to turn to the periodic table again. Elements that are vertically lower have heavier nuclei and larger electronic shells, so silicon, due to its size, is less suitable for such precise tasks as building DNA. Thus, in another part of the Universe, the development of an organism based on silicon is theoretically possible, but on our planet this is unlikely to happen.
Silicon will continue to appear in the news for a long time, because even if some element replaces it as the basis for computer calculations, it will take a very long time before the transition is complete. In addition, there are other areas of its application, and it is possible that new ways of using this substance will be found. In all likelihood, silicon will remain one of the main substances in the physical world of human activity.