KR20070039175A - Ideal oxygen precipitating silicon wafers with nitrogen/carbon stabilized oxygen precipitate nucleation centers and process for making the same - Google Patents

Abstract

The present invention provides a silicon wafer in which the oxygen deposit behavior is controlled such that a sufficient amount of wafer bulk is ultimately formed for inherent gettering purposes and a denude region extending inward from the front surface. Specifically, prior to forming the oxygen precipitate, the wafer bulk includes a dopant stabilized oxygen precipitate nucleation center. The dopant is selected from the group containing nitrogen and carbon, and the concentration of the dopant is sufficient to withstand thermal treatments such as epitaxial deposition while maintaining the ability of the oxygen precipitate nucleation center to dissolve any grown nucleation centers. Has a value.

Dinude zone, inherent gettering, stabilized oxygen deposit nucleation center, epitaxial deposition

Description

IDEAL OXYGEN PRECIPITATING SILICON WAFERS WITH NITROGEN / CARBON STABILIZED OXYGEN PRECIPITATE NUCLEATION CENTERS AND PROCESS FOR MAKING THE SAME

1 is a schematic diagram illustrating the method of the present invention.

The present invention relates generally to the manufacture of semiconductor material substrates, in particular silicon wafers, used in the manufacture of electronic components. More specifically, the present invention relates to a method of processing a silicon wafer, which makes it possible to form oxygen deposits that are ideal for the electronic device manufacturing method and that are not uniform in depth distribution during the heat treatment cycle of any electronic device manufacturing method.

In most manufacturing processes of semiconductor electronic components, single crystal silicon, which is a starting material, is commonly manufactured by the so-called Czochralski precess, in which a single crystal seed is immersed in molten silicon and then grown by slow extraction. When molten silicon is contained in a quartz crucible, the molten silicon is contaminated by various impurities (mainly oxygen). At the temperature of the molten silicon mass, oxygen enters the crystal lattice until it reaches a concentration determined by the oxygen solubility in silicon at the temperature of the molten mass and the actual segregation coefficient of oxygen in the solidified silicon. do. This concentration is greater than the solubility of oxygen in solid silicon at typical temperatures of electronic device fabrication. Therefore, when crystals grow from the molten mass and cool down, the oxygen solubility therein rapidly decreases, with the result that oxygen is present at the supersaturation concentration in the slice or wafer.

Heat treatment cycles typically used in the manufacture of electronic devices can cause the precipitation of oxygen in oxygen-saturated silicon wafers. Precipitates in the wafer may be harmful or beneficial depending on their location. Oxygen deposits located in the active device region of the wafer can degrade device operation. However, oxygen deposits located in the bulk of the wafer may trap undesirable metal impurities that may come into contact with the wafer. Trapping the metal using oxygen deposits located in the bulk of the wafer is commonly referred to as internal or intrinsic gettering ("IG").

Historically, electronic device fabrication methods have zones or regions free of oxygen deposits near the surface of the wafer (commonly referred to as "denuded zones" or "no precipitation zones") and the rest of the wafer, i.e. wafer bulk. Contains a series of steps designed to produce silicon containing a sufficient number of oxygen precipitates for IG purposes. The denude zone may be subjected to, for example, (a) an oxygen out-diffusion heat treatment at high temperature (at least 1100 ° C.) in an inert atmosphere for at least about 4 hours, and (b) low temperature (600-750 ° C.) In the order of heating from high temperature to low temperature to high temperature, such as performing oxygen precipitate nucleation at, and (c) growing oxygen (SiO ₂ ) precipitate at high temperature (1000-1150 ° C.). See, for example, pages 361-367 of F. Shimura's Semiconductor Silicon Crystal Technology (1989), Academic Press, Inc., San Diego, Calif., And references cited therein.

However, more recently, advanced electronic device manufacturing processes, such as DRAM manufacturing processes, have begun to minimize the use of high temperature processing steps. Although some of these processes maintain sufficient hot treatment steps to produce a denude zone and sufficient bulk deposit concentration, the tolerance of the material is too stringent to provide a commercially meaningful product. Currently, other highly advanced electronic device manufacturing processes do not include any external diffusion steps. Therefore, due to the problems associated with oxygen deposits in the active device area, these electronic device manufacturers must use silicon wafers that cannot form oxygen deposits anywhere on the wafer under their processing conditions. As a result, all IG potential is lost.

It is therefore an object of the present invention to provide a single crystal silicon wafer which essentially forms oxygen precipitates of ideal non-uniform depth distribution during the heat treatment cycle of any electronic device manufacturing process; Providing a single crystal silicon wafer that optimally and reproducibly forms an oxygen precipitate of sufficient density in the denude zone and wafer bulk of sufficient depth; Providing a single crystal silicon wafer in which the formation of the denude zone and the formation of oxygen precipitates in the wafer bulk do not depend on the oxygen concentration difference in these areas of the wafer; Providing a single crystal silicon wafer whose thickness of the resulting denude region is essentially independent of the details of the integrated circuit fabrication process sequence; The formation of the denude zone and the formation of oxygen precipitates in the wafer bulk are not affected by the thermal history and oxygen concentration of the monocrystalline silicon ingot grown by the Czochralski method in which the silicon wafer is sliced. Providing a silicon wafer; Providing a process in which the formation of the denude zone does not depend on the external diffusion of oxygen; And silicon is doped with nitrogen and / or carbon in sufficient concentration to stabilize the oxygen precipitate necleation center to withstand subsequent rapid heat treatment without disturbing the formation of the denude zone. There is.

Therefore, for simplicity, the present invention provides two roughly parallel major surfaces, one major surface being the front surface of the wafer and the other major surface being the back surface of the wafer, and a central plane between the front and rear surfaces. And a peripheral edge joining the front side and the back side. The wafer also includes a dopant selected from the group consisting of nitrogen and carbon, wherein the concentration of the dopant is when the wafer is cooled at a predetermined rate R from the first temperature T ₁ to the second temperature T ₂ . This is sufficient to promote the formation of stabilized oxygen precipitate nucleation centers. The stabilized oxygen precipitate nucleation center cannot dissolve at temperatures below about 1150 ° C. but at temperatures between about 1150 ° C. and about 1300 ° C. T ₁ has a value between about 1150 ° C. and about 1300 ° C. T ₂ is the temperature at which the crystal lattice vacancy is relatively non-moving in silicon. R is at least about 5 ° C./sec. The wafer also includes a surface layer comprising an area of the wafer between the front face and the distance D measured from the front face toward the center face, which is free of stabilized oxygen precipitate nucleation centers. The wafer also includes a bulk layer comprising a second wafer region between the center plane and the surface layer, which includes a stabilized oxygen precipitate nucleation center.

The present invention also provides two substantially parallel major surfaces, one main surface being the front surface of the wafer and the other major surface being the rear surface of the wafer, the central surface between the front and rear surfaces, and the front and rear surfaces. A single crystal silicon wafer having peripheral edges to join thereto. The wafer includes a dopant selected from the group consisting of nitrogen and carbon. When nitrogen is a dopant, the concentration of nitrogen has a value of about 1 × 10 ¹² atoms / cm 3 to about 5 × 10 ¹⁴ atoms / cm 3. When carbon is a dopant, the concentration of carbon has a value of about 1 × 10 ¹⁶ atoms / cm 3 to about 4 × 10 ¹⁷ atoms / cm 3. The wafer also includes a surface layer comprising an area of the wafer between the front face and the distance D measured from the front face toward the center face, which has no stabilized oxygen precipitate nucleation center. Additionally, the wafer includes a bulk layer comprising a second wafer region between the midplane and the surface layer, which includes a stabilized oxygen precipitate nucleation center.

In another embodiment, the present invention is directed to a silicon on insulator (SOI) structure comprising a single crystal handle wafer, a single crystal silicon device layer, and an insulating layer between the handle wafer and the device layer. The single crystal silicon handle wafer has two roughly parallel major faces, one main face being the front face of the wafer and the other major face being the back face of the wafer, the middle face between the front and back faces, and the front and back faces. A peripheral edge that joins. The handle wafer also includes a dopant selected from the group consisting of nitrogen and carbon, wherein the concentration of the dopant is such that the wafer is cooled at a predetermined rate R from the first temperature T ₁ to the second temperature T ₂ . When present, it has a concentration sufficient to promote the formation of stabilized oxygen precipitate nucleation centers. The stabilized oxygen precipitate nucleation center cannot dissolve at temperatures below about 1150 ° C. but at temperatures between about 1150 ° C. and about 1300 ° C. T ₁ has a value between about 1150 ° C. and about 1300 ° C. T ₂ is the temperature at which the crystal lattice vacancy is relatively non-moving in silicon. R is at least about 5 ° C./sec. The handle wafer also includes a surface layer comprising an area of the wafer between the front face and the distance D measured from the front face toward the center face, which has no stabilized oxygen precipitate nucleation center. The handle wafer also includes a bulk layer comprising a second wafer region between the midplane and the surface layer, which includes a stabilized oxygen precipitate nucleation center.

The present invention also relates to a method of making a single crystal silicon wafer having a controlled oxygen precipitation aspect. This method is a front surface, which is sliced from a single crystal silicon ingot grown by the Czochralski method and comprises a front surface, a back surface, a center surface between the front and rear surfaces, and a wafer region between the front surface and the distance D measured from the front surface to the central surface. Selecting a wafer comprising a layer, and a bulk layer comprising a wafer region between the midplane and the front layer. The wafer also includes a dopant selected from the group consisting of nitrogen and carbon, wherein the concentration of the dopant is when the wafer is cooled at a predetermined rate R from the first temperature T ₁ to the second temperature T ₂ . This is sufficient to promote the formation of stabilized oxygen precipitate nucleation centers. The stabilized oxygen precipitate nucleation center cannot dissolve at temperatures below about 1150 ° C. but at temperatures between about 1150 ° C. and about 1300 ° C. T ₁ has a value between about 1150 ° C. and about 1300 ° C. T ₂ is the temperature at which the crystal lattice vacancy is relatively non-moving in silicon. R is at least about 5 ° C./sec. The method includes heating the wafer to a temperature of at least about 1150 ° C. to form crystal lattice vacancy in the front layer and the bulk layer, and rotating the heated wafer at a predetermined rate to form a vacancy concentration profile in the wafer. Cooling, wherein the highest density of bacony is present in the bulk layer, the concentration generally decreasing from the position of the highest density toward the front side of the wafer, and the difference in bacony concentration in the front layer and the bulk layer is stabilized. The oxygen precipitate nucleation center is not formed in the front layer, but the stabilized oxygen precipitate nucleation center is formed in the bulk layer. The method also includes forming a stabilized oxygen precipitate nucleation center in the bulk layer as the wafer cools, wherein the concentration of the stabilized oxygen precipitate nucleation center in the bulk layer depends primarily on the concentration of baconsea.

In another embodiment, the present invention is directed to a method of making a single crystal silicon wafer having a controlled oxygen precipitation aspect. This method is a front surface, which is sliced from a single crystal silicon ingot grown by the Czochralski method and comprises a front surface, a back surface, a center surface between the front surface and the rear surface, and a wafer region between the front surface and the distance D measured from the front surface toward the center surface. Selecting a wafer comprising a layer, and a bulk layer comprising a wafer region between the midplane and the front layer. The wafer also includes a dopant selected from the group consisting of nitrogen and carbon. When nitrogen is a dopant, the concentration of nitrogen has a value of about 1 × 10 ¹² atoms / cm 3 to about 5 × 10 ¹⁴ atoms / cm 3. When carbon is a dopant, the concentration of carbon has a value of about 1 × 10 ¹⁶ atoms / cm 3 to about 4 × 10 ¹⁷ atoms / cm 3. The method includes heat treating the wafer to form crystal lattice vacancy in the front and bulk layers. The annealed wafer has a vacancy concentration profile in the wafer-the highest density of bacony is present in the bulk layer, and the concentration generally decreases toward the front of the wafer from the highest density location, and the vacancy in the front layer and the bulk layer The difference in concentration is cooled at a rate such that stabilized oxygen precipitate nucleation centers are not formed in the front layer but stabilized oxygen precipitate nucleation centers are formed in the bulk layer. In addition, when the heat treated wafer is cooled, a stabilized oxygen precipitate nucleation center is formed in the bulk layer, and the concentration of the stabilized oxygen precipitate nucleation center in the bulk layer mainly depends on the concentration of baconci.

Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.

In accordance with the present invention, during essentially any electronic device fabrication process, an ideal precipitated wafer has been found that forms a wafer bulk with sufficient depth of denude zone and sufficient density of oxygen precipitate for IG purposes. Advantageously, this ideal precipitated wafer can be manufactured in minutes using tools commonly used in the semiconductor silicon manufacturing industry. This process creates a "template" in silicon that determines or "prints" how oxygen ultimately precipitates. According to the invention, this template is stabilized to withstand subsequent rapid heat treatments (ie epitaxial deposition and / or oxygen injection) without an intermediate thermal stabilization annealing step.

A. Starting Material

The starting material of the ideal precipitation wafer of the present invention is a single crystal silicon wafer comprising nitrogen and / or carbon as dopant. The concentration of the dopant is chosen to have two desirable properties: i) the ability to dissolve any oxygen precipitation nucleation centers in the starting wafer so that oxygen ultimately precipitates according to the ideal template (i.e., the denude zone is oxygenated). No deposits, the inherent gettering regions of the wafer bulk include oxygen precipitates, and ii) the nucleation centers do not dissolve during subsequent rapid heat treatments such as epitaxial deposition, and do not erase the already installed precipitation templates. It is selected to provide the ability to grow sufficiently large and stable oxygen precipitate nucleation centers during the process of the invention. In order to realize the benefits of stabilization while maintaining the ability to form a denude zone, the concentration of dopant in silicon typically ranges from about 1 × 10 ¹² atoms / cm 3 (about 0.00002 ppma) to about 1 × 10 ¹⁵ atoms / cm 3 (about 0.002 ppma). In another embodiment of the present invention, the concentration of nitrogen has a value between about 1 × 10 ¹² atoms / cm 3 and about 1 × 10 ¹³ atoms / cm 3 (about 0.0002 ppma). If the concentration of nitrogen is too low, for example, less than about 1 × 10 ¹² atoms / cm 3 (about 0.00002 ppma), the stabilizing effect will not be realized (ie, nucleation centers may dissolve at temperatures below about 1150 ° C.). ). On the other hand, if the nitrogen concentration is too high, for example exceeding about 1 × 10 ¹⁵ atoms / cm 3 (about 0.002 ppma), the oxygen precipitation nucleation center formed during crystal growth dissolves during the rapid heat treatment annealing step of the present invention. Will not be.

Additionally, if silicon crystals contain too much nitrogen, oxidation induced stacking faults (OISFs) are formed throughout the wafer that negatively affect the quality of the wafer and any epitaxial layers deposited thereon. Tendency (see Japanese Patent Laid-Open No. 1999-189493). Specifically, the OISF on the silicon wafer surface is not covered by the deposition of the epitaxial silicon layer, unlike other vacancy type defects. OISF continues to grow through the epitaxial layer and causes grow-in defects, commonly referred to as epitaxial stacking defects. The epitaxial stacking defects have a maximum cross-sectional width from the current detection limit of the laser based automated inspection device of about 0.1 μm to about 10 μm.

In accordance with the present invention, the wafer may include carbon instead of or with nitrogen to stabilize the oxygen precipitate nucleation center. In one embodiment, the concentration of carbon in silicon has a value of about 1 × 10 ¹⁶ atoms / cm 3 (0.2 ppma) to about 4 × 10 ¹⁷ atoms / cm 3 (8 ppma). In another embodiment, the concentration of carbon has a value of about 1.5 × 10 ¹⁶ atoms / cm 3 (0.3 ppma) to about 3 × 10 ¹⁷ atoms / cm 3 (6 ppma).

Silicon grown by the Czochralski method typically has an interstitial oxygen concentration in the range of about 5 × 10 ¹⁷ atoms / cm 3 to about 9 × 10 ¹⁷ atoms / cm 3. Since the aspect of oxygen precipitation of the wafer is essentially decoupled from the oxygen concentration in the ideal precipitated wafer, the starting wafer may have an oxygen concentration within or in some cases outside of the range that is maintainable by the Czochralski method. .

During the growth of a single crystal silicon ingot having below the typical impurity levels of nitrogen and / or carbon, the silicon is cooled from its melting temperature (about 1410 ° C.) and as the silicon passes through about 700 ° C. to about 350 ° C. Bacillus and oxygen interact to form an oxygen deposit nucleation center within the ingot. Without being bound by a particular theory, it is currently believed that nitrogen / carbon dopant atoms promote the formation of oxygen precipitate nucleation centers by retarding the diffusion of baconcies in single crystal silicon. Specifically, when the concentration of nitrogen and / or carbon increases above the impurity level, the concentration of bacony also increases at a given temperature, thereby raising the temperature at which critical supersaturation of bacony and oxygen occurs. As a result, the critical supersaturation temperature of silicon with concentrations of nitrogen and / or carbon within the scope of the present invention is shifted between about 800 ° C and about 1050 ° C. At higher critical supersaturation temperatures, the concentration of baconcies is higher, and oxygen atoms become more mobile, increasing the interaction of baconcies and oxygen, thus allowing the formation of larger and more stable oxygen precipitate nucleation centers. do.

According to the present invention, it is not important whether the nucleation center is present in the starting material, since the nucleation center can be dissolved by heat treatment of silicon at a temperature of about 1150 ° C to 1300 ° C. Although the presence (or density) of the oxygen precipitate nucleation center cannot be directly measured using currently available techniques, their presence is annealed at 1000 ° C. for 4 hours and then annealed at 1000 ° C. for 16 hours. It can be detected by performing an oxygen precipitation heat treatment such as The limit of detection of oxygen deposits is currently about 5 × 10 ⁶ precipitates / cm 3.

Wafers are sliced from ingots grown according to conventional Czochralski crystal growth methods. During ingot growth, nitrogen and / or carbon can be introduced into the ingot in several ways, including, for example, by introducing gaseous nitrogen / carbon into the growth chamber and / or adding solid nitrogen / carbon to the polycrystalline silicon melt. have. This method is typically used because the amount of dopant added to the growth crystals can be controlled more accurately by adding solid dopants to the polycrystalline silicon melt. For example, the amount of nitrogen / carbon added to the crystals may be a known thickness of silicon nitride (Si ₃ N ₄ ) on a known diameter silicon wafer introduced into a crucible, for example, with polycrystalline silicon prior to forming the silicon melt. Or by depositing a layer of silicon carbide (SiC) (the density of Si ₃ N ₄ and SiC is about 3.18 g / cm 3 and about 3.21 g / cm 3, respectively).

Standard silicon slicing, lapping, etching and polishing techniques as well as standard Czochralski growth methods are described, for example, in F. Shimura, Semiconductor Silicon Crystal Technology, Academic Press, 1989, and Silicon Chemical Etching , (J. Grabmaier). ed.), Springer-Verlag, New York, 1982, which is incorporated herein by reference. The starting material for the process of the present invention may be a polished silicon wafer or, alternatively, a silicon wafer that is wrapped and etched but not polished. In addition, the wafer may have vacancy or self-interstitial point bonding as the dominant intrinsic point defect. For example, a wafer may be dominant in vacancy from center to edge, self interstitial may be dominant from center to edge, or the wafer may be in a ring of self interstitial dominant material that is symmetric along the axial direction. It may comprise a central core of the bacon dominant material surrounded by.

Referring now to FIG. 1, the single crystal silicon wafer 1, which is the starting material of the ideal precipitation wafer of the present invention, has a front face 3, a back face 5, and a virtual center face 7 between the front face and the back face. . As used herein, the terms "front" and "back" are used to distinguish between two substantially flat major surfaces of the wafer. As used herein, the front surface of the wafer does not necessarily have to be the surface on which the electronic device is to be manufactured later, and the term used herein does not necessarily have to be the main surface of the wafer as opposed to the surface on which the electronic device is manufactured. . Furthermore, since the silicon wafer typically has any total thickness variation (TTV), warp and bow, the midpoint between each point on the front and each point on the back is in the plane. It may not be located correctly. However, as a practical matter, it can be said that, in terms of approximation, the midpoint is located in an imaginary central plane that is approximately equidistant between the front and rear sides since TTV, torsion and warpage are typically very mild.

B. Bacony Formation on Doped Silicon Wafers

According to the invention, the wafer is placed in a heat treatment step S ₂ (optional step S ₁ is described in detail later), in which the wafer forms crystal lattice vacancy 13 in this wafer 1 and Heat treatment is performed at high temperature to increase the number density. Preferably, this heat treatment step is performed in a rapid thermal annealer (RTA) in which the wafer is rapidly heated to a target temperature T1 and annealed for a relatively short time at that temperature (eg rapid thermal The annealing processor can heat the wafer from room temperature to 1200 ° C. in a few seconds). One such commercially available RTA furnace is the Model 2800 furnace sold by STEAG AST Electronic GmbH (Dornstad, Germany). Generally, the wafer is heat treated at a temperature of 1150 ° C. to less than about 1300 ° C. Typically, the wafer is heated to a temperature between about 1200 ° C and about 1275 ° C, and more typically at a temperature between about 1225 ° C and 1250 ° C.

Intrinsic point defects (Basic and Silicon Self-Interstitial) can diffuse through single crystal silicon at a temperature dependent diffusion rate. Therefore, the concentration profile of the intrinsic point defect is a function of the recombination rate and the diffusivity of the intrinsic point defect as a function of temperature. For example, intrinsic point defects are relatively mobile at temperatures near the temperature at which the wafer is annealed in the rapid thermal annealing step, but are essentially non-movable for all commercially significant times at temperatures of about 700 ° C. Experimental evidence thus far shows that the effective diffusion rate of baconsea is significantly slower at temperatures below about 700 ° C. and possibly at temperatures of 800 ° C., 900 ° C. or even 1000 ° C .; At lower temperatures, it is suggested that baconcies can be considered non-mobile for any commercially significant time.

In addition to forming crystal lattice vacancy, the rapid thermal annealing step causes the dissolution of existing oxygen precipitate nucleation centers present in the silicon starting material. Such nucleation centers may be formed, for example, during the growth of a single crystal silicon ingot in which the wafer is sliced, or may be formed as a result of some other event in the previous thermal history of the wafer or ingot in which the wafer is sliced. Can be. Thus, if the nucleation center can be dissolved during the rapid thermal annealing step, it is not important that the nucleation center is present or absent in the starting material.

During the heat treatment, the wafer is exposed to an atmosphere comprising a gas or gases selected to form a uniform concentration profile in one embodiment that is relatively uniform and in other embodiments a non-uniform vacancy concentration profile.

1. Examples of non-nitriding and non-oxidizing atmospheres

In one embodiment, the wafer 1 is heat treated in a non-nitriding atmosphere and a non-oxidizing atmosphere (ie, inert atmosphere). When a gas containing no nitrogen and oxygen is used as the atmosphere in the rapid thermal annealing step and the cooling step, an increase in vacancy concentration throughout the wafer, even if not immediately, is achieved when the annealing temperature is reached. The resulting vacancy concentration (number density) profile formed on the wafer during heat treatment is relatively constant from the front of the wafer to the back of the wafer. Generally, the wafer is for at least one second, typically for at least several seconds (eg, at least 3 seconds), preferably for several tens of seconds (eg, 20 seconds, 30 seconds, 40 seconds, or 50 seconds). And at this temperature for up to about 60 seconds (this is near the limit of a commercially available rapid thermal annealing processor), depending on the desired wafer characteristics. Further maintenance at the established temperature for an additional time during the annealing of the wafer, according to the experimental evidence obtained to date, no longer shows an increase in vacancy concentration. Suitable gases include argon, helium, neon, carbon dioxide, and other inert monoatomic and inert compound gases, or mixtures of these gases.

According to the experimental evidence obtained to date, the non-nitriding / non-oxidizing atmosphere preferably has a relatively small partial pressure of oxygen, water vapor and other oxidizing gases. That is, the atmosphere contains no oxidizing gas or insufficient gas to inject a sufficient amount of silicon self interstitial atoms sufficient to suppress an increase in vacancy concentration. The lower limit of the oxidizing gas concentration was not accurately determined, but it was proved that no increase in vacancy concentration and no other effects were found for oxygen partial pressures of 0.01 atm or parts per million atomic ppm. Thus, the atmosphere preferably has a partial pressure of oxygen and other oxidizing gases of less than 0.01 atm (10000 ppma). More preferably, the partial pressure of these gases in the atmosphere is about 0.005 atm (5000 ppma) or less, even more preferably 0.002 atm (2000 ppma) or less, most preferably 0.001 atm (1000 ppma) or less.

2. Examples of Apparent Oxide Layers / Nitriding Atmospheres

In another embodiment of the method according to the invention, the wafer 1 is, in step S ₁ , heat-treated in an oxygen containing atmosphere to grow a superficial oxide layer surrounding the wafer 1 before step S ₂ . . In general, the oxide layer has a greater thickness than the native oxide layer (about 15 angstroms) formed on silicon. In this second embodiment, the thickness of the oxide layer is typically at least about 20 Angstroms. In some examples, the wafer will have an oxide layer that is at least about 25 or 30 Angstroms thick. However, experimental evidence obtained to date indicates that oxide layers with a thickness of about 30 Angstroms or more provide little or no additional benefit, although they do not interfere with the desired effect.

After forming the oxide layer, the rapid thermal annealing step is typically carried out in the presence of a nitriding atmosphere, i.e. an atmosphere comprising a nitrogen gas (N ₂ ) or a nitrogen-containing compound gas such as ammonia, which can nitride the exposed silicon surface. do. Alternatively or additionally, the atmosphere may comprise a non-oxidizing, non-nitriding gas, such as argon. The increase in vacancy concentration across the wafer is achieved when the annealing temperature is reached, although not immediately, and the vacancy concentration profile of the wafer is relatively uniform.

3. Example of natural oxide layer / nitridation atmosphere

In a third embodiment, the starting wafer has only a native oxide layer. When such a wafer is annealed in a nitriding atmosphere, the effect is different from that observed in the second embodiment. In particular, when a wafer with an increased oxide layer is annealed in a nitrogen atmosphere, a substantially uniform increase in vacancy concentration is achieved throughout the wafer when the anneal temperature is reached, even if not immediately. Moreover, the vacancy concentration does not appear to increase significantly with annealing time at a given annealing temperature. If the wafer is nothing other than the native oxide layer, and if the front and back sides of the wafer are annealed in nitrogen, then the wafer will have a vacancy concentration profile (number density) of approximately "U-shaped" with respect to the cross section of the wafer. That is, the maximum concentration of bacon will occur at or between a few micrometers from the front and back, and relatively constant and lower concentrations will appear throughout the wafer bulk, initially increasing the minimum concentration in the wafer bulk. Approximately equal to the concentration obtained on a wafer with an oxide layer. Moreover, an increase in the annealing time will result in an increase in vacancy concentration in the wafer with nothing other than the native oxide layer.

Thus, referring again to FIG. 1, the segment with only the native oxide layer is annealed in accordance with the method of the present invention under a nitriding atmosphere, and the resulting maximum concentration or maximum concentration of bacony is generally initially defined in regions 15. And 15 '), the bulk 17 of the silicon segment will include relatively lower concentrations of bacony and nucleation centers. Typically, these highest concentration regions will be located within a few microns (ie about 5 or 10 microns), or tens of microns (ie about 20 or 30 microns), up to about 40 to 60 microns from the silicon segment surface.

4. Oxygen-containing atmosphere

When the atmosphere in the rapid thermal annealing step and the cooling step includes oxygen, or more specifically, with nitrogen containing gas, inert gas or both, oxygen gas (O ₂ ) or oxygen containing gas (eg exothermic When including pyrogenic steam, the vacancy concentration profile in the region near the surface is affected. Experimental evidence to date has shown that the vacancy concentration profile in the region near the surface has an inverse relationship with the oxygen concentration in the atmosphere. Without being bound by any particular theory, it is generally believed that at sufficient concentrations, the annealing of oxygen acts to cause oxidation of the silicon surface, resulting in inward flux of the silicon self interstitial. Lose. The flow of the silicon self interstitial is controlled by the rate of oxidation, which can be controlled by the partial pressure of oxygen in the atmosphere. This inward flow of the self interstitial causes recombination to gradually change the vacancy concentration profile, starting at the surface and moving inward, and the rate of inward travel increases as a function of increasing oxygen partial pressure. When oxygen is used with the nitrogen-containing gas in the atmosphere during heat treatment S ₁ and / or S ₂ , an “M-shaped” vacancy profile can be obtained, with the maximum or highest vacancy concentration being the wafer between the midplane and the surface layer. Present in the bulk (the concentration generally decreases in either direction). As a result of the presence of oxygen in the atmosphere, regions of low vacancy concentrations of any depth may be created.

In addition, experimental evidence shows that the difference in behavior of a wafer with only a native oxide layer and that of a wafer with an increased oxide layer can be avoided by including oxygen molecules or other oxidizing gases in the atmosphere. In other words, when a wafer with only natural oxides is annealed in a nitrogen atmosphere containing a small partial pressure of oxygen, the wafer behaves the same as a wafer with an increased oxide layer (ie, a relatively uniform concentration pile Formed in the wafer). Without wishing to be bound by any theory, a superficial oxide layer whose thickness is larger than the native oxide layer acts as a shield to prevent nitriding of silicon. Thus, this oxide layer may be present on the starting wafer, or may be formed by growing an increased oxide layer in situ during the annealing step. If this is desired, the atmosphere during the rapid thermal annealing step preferably comprises a partial pressure of at least about 0.0001 atm (100 ppma), more preferably a partial pressure of at least about 0.0002 atm (200 ppma). However, for the reasons described above, the partial pressure of oxygen preferably does not exceed 0.01 atm (10000 ppma), more preferably less than 0.002 atm (2000 ppma), most preferably less than 0.001 atm (1000 ppma).

Therefore, in the fourth embodiment, the atmosphere during the rapid thermal annealing step typically contains sufficient oxygen partial pressure to achieve a denude zone depth of less than about 30 microns. Typically, the denude zone depth can range from at least about 5 microns to less than about 30 microns, and can range from about 10 microns to about 25 microns, or from about 15 microns to about 20 microns. More specifically, the heat treatment may include nitrogen containing gas (eg N ₂ ), non-oxygen, non-nitrogen containing gas (eg argon, helium, etc.), or mixtures thereof, and oxygen containing gas (eg, An atmosphere comprising O ₂ or pyrogenic steam), and less than about 500 ppma (eg, at least about 1 ppma, 5 ppma, 10 ppma or more) to produce an inward flow of self interstitial, It may preferably be carried out in an atmosphere having an oxygen partial pressure of less than about 400 ppma, 300 ppma, 200 ppma, 150 ppma or 100 ppma, and in some embodiments, preferably less than about 50, 40, 30, 20 or 10 ppma. When a mixture of nitrogen-containing gas and non-nitrogen, non-oxygen-containing gas is used with oxidizing gas, each ratio of the two gases (e.g., the ratio of nitrogen-containing gas to inert gas) is about 1:10 to about 10: 1, From about 1: 5 to about 5: 1, about 1: 4 to about 4: 1, about 1: 3 to about 3: 1, about 1: 2 to about 2: 1, and about 1: 5, 1: A ratio of nitrogen containing gas to inert gas of 4, 1: 3, 1: 2 or 1: 1 is preferred in some embodiments. In other words, if such a gaseous mixture is used as the atmosphere for the annealing and cooling steps, the concentration of nitrogen containing gas is from about 1% to less than about 100%, from about 10% to about 90%, about 20 From% to about 80%, from about 40% to about 60%.

5. Simultaneous Exposure to Different Atmospheres

In other embodiments of the invention, the front and back surfaces of the wafer may be exposed to different atmospheres each containing one or more nitriding or non-nitriding gases. For example, the back side of the wafer may be exposed to the nitriding atmosphere when the front side of the wafer is exposed to the non-nitriding atmosphere. Wafers subjected to heat treatment in different atmospheres may have an asymmetric vacancy concentration profile depending on the conditions of each surface and the atmosphere to which the wafer is exposed. For example, if the front side has nothing but a native oxide layer and the back side has an increased oxide layer and the wafer is thermally treated in a nitriding atmosphere, the vacancy concentration in the first half of the wafer will naturally be similar to the "U-shaped" profile and the wafer The latter part will be uniform. Alternatively, multiple wafers (eg, two, three or more wafers) can be stacked and annealed simultaneously in a face-to-face configuration, and when annealed in this manner In other words, the faces in face-to-face contact are mechanically shielded from the atmosphere during annealing. Alternatively, and depending on the atmosphere used in the rapid thermal annealing step and the desired oxygen precipitation profile of the wafer, the oxide layer may be formed only on one surface of the wafer (eg, the front surface 3).

C. Rapid Cooling of Heat Treated and Doped Silicon Wafers

When completing the step S _2, the wafer has a temperature (T ₂₎ step to S ₃ is when the crystal lattice bacon through the relatively moving temperature range in the single crystal silicon, at least during the crystal lattice bacon is that in the silicon in a relatively non-dynamic Is cooled rapidly. When the temperature of the wafer decreases through this range of temperatures, the babies diffuse and disappear into the native oxide layer on the surface of the wafer and / or the wafer surface, thus changing the vacancy concentration profile, the degree of change It depends on the length of time the wafer remains within this temperature range. If the wafer is maintained in this temperature range for an indefinite period of time, the vacancy concentration profile once again becomes similar to the initial profile in step S ₂ (eg, becomes uniform, “U-shaped” or asymmetric), The equilibrium of concentration will be less than the concentration immediately after the heat treatment step is completed. However, by rapidly cooling the wafer, the distribution of crystal lattice vacancy in the region near the surface is greatly reduced to modify the vacancy concentration profile. For example, rapidly cooling a wafer with an initially uniform profile results in an uneven profile, where the maximum vacancy concentration is at or near the midplane 7, and the vacancy concentration is It decreases toward the front 3 and back 5 of the wafer. If the vacancy concentration profile before cooling is "U-shaped", the final concentration profile after rapid cooling of the wafer will be "M-shaped". That is, the vacancy concentration profile is one local minimum concentration similar to the U-shaped profile before rapid cooling of the wafer near the center plane, and the two local maximum concentrations generated by suppressing the vacancy in the surface area, i.e., the central and front surfaces. There will be one local maximum concentration between and one local maximum concentration between the midplane and the back. Finally, if the vacancy concentration profile before cooling is asymmetrical, the final concentration will have one local maximum profile similar to the "M" shaped profile between one surface and the midplane, formed after cooling the uniform concentration profile. Similar to the resulting profile, concentrations will generally decrease from the central plane to other surfaces.

Generally, within this temperature range the average cooling rate R is at least about 5 ° C./sec, preferably at least about 20 ° C./sec. Depending on the desired depth of the denude zone, the average cooling rate may preferably be at least about 50 ° C./second, more preferably 100 ° C./second, and for some applications at present from about 100 ° C./second to about 200 ° C./second. Cooling rates in the range are preferred. Once the wafer is cooled to a temperature below the temperature range where the crystal lattice vacancy is relatively mobile in monocrystalline silicon, the cooling rate does not appear to significantly affect the deposition characteristics of the wafer and therefore is not considered to be of great importance. As explained above, the experimental evidence thus far obtained shows that the effective diffusion rate of bacon is typically significantly slower at temperatures below about 700 ° C., and at lower temperatures, bacons are non-mobile for any commercially viable time. It is thought to be. Conveniently, the cooling step can be carried out in the same atmosphere in which the heating step is carried out.

During step S ₃ , baconcis and interstitial oxygen in the wafer interact to form an oxygen precipitate nucleation center. The concentration of the oxygen precipitate nucleation center depends mainly on the baconcy concentration, so the profile of the oxygen precipitate nucleation center corresponds to the profile of baconcy. Specifically, the oxygen precipitate nucleation center is formed in the high vacancy region (wafer bulk), and the oxygen precipitate nucleation center is not formed in the low vacancy region (wafer surface). Thus, by dividing the wafer into various zones of vacancy concentration, a template for the oxygen precipitate nucleation center is created. In addition, the distribution of oxygen precipitate nucleation centers in the wafer bulk corresponds to the distribution of baconcies. That is, the distribution may be non-uniform, for example having a profile characterized by an "M-shaped" or asymmetric, having a maximum concentration at or near the central plane and decreasing toward the front and back sides of the wafer.

In accordance with the present invention, the oxygen precipitate nucleation centers formed in the wafer bulk are "stabilized" upon completion of rapid thermal annealing. That is, subsequent long time (eg, several hours) heat treatments are not required to grow nucleation centers to a size that can withstand rapid heat treatments such as epitaxial deposition. As described above, at present nitrogen and / or carbon dopant atoms are believed to inhibit the diffusion of baconcies in silicon, which increases the temperature at which the critical supersaturation of baconcies occurs, ultimately forming a stable oxygen deposit nucleation center. (Ie they cannot dissolve at temperatures below about 1150 ° C).

After step S ₃ , the wafer comprises a first layer of the wafer between the front face and the distance D measured from the front face to the center face and is free of oxygen deposit nucleation centers and between the middle face and the first area and stabilized. And a bulk layer comprising an oxygen precipitate nucleation center. The concentration of dopant in the wafer causes the stabilized oxygen precipitate nucleation center to dissolve at temperatures ranging from about 1150 ° C to 1300 ° C. Thus, the stabilized oxygen precipitate nucleation center can withstand subsequent heat treatments such as epitaxial deposition without disturbing the dissolution of the oxygen precipitate nucleation centers grown during step S ₂ .

D. Oxygen Sediment Growth

In step S ₄ , the wafer is subjected to an oxygen precipitate growth heat treatment to grow a stabilized oxygen precipitate nucleation center in the oxygen precipitate. For example, the wafer may be annealed for 16 hours at a temperature of 800-1000 ° C. Alternatively and preferably, the wafer is loaded into a furnace at 800-1000 ° C. as a first step in the electronic device manufacturing process. As the temperature increases to 800 ° C. or higher, oxygen precipitate nucleation clusters continue to grow in the precipitate by consuming baci and interstitial oxygen, while oxygen precipitate nucleation centers form in regions near the surface. And nothing happens.

As shown in FIG. 1, the resulting depth distribution of the oxygen precipitates in the wafer is a clear region (denude zone) of oxygen precipitate free material extending from the front face 3 and back face 5 to depths t and t ', respectively. ) Is characteristic. Between the oxygen precipitate free zones 15, 15 ′, there is a region 17 containing a concentration profile of non-uniform oxygen precipitate with a profile that depends on the profile of baconcies as described above.

The concentration of the oxygen precipitate in that region 17 is primarily a function of the heating step and secondly a function of the cooling rate. In general, the concentration of the oxygen precipitate increases with increasing temperature and annealing time in the heating step, and a precipitate density ranging from about 1 × 10 ⁷ to about 5 × 10 ¹⁰ precipitates / cm 3 is routinely obtained.

The respective depths from the front and back of the oxygen precipitate free material (the denude zone) 15, 15 ′ are primarily a function of the cooling rate in the temperature range in which the crystal lattice vacancy is relatively mobile in silicon. In general, the depths t, t 'increase with decreasing cooling rate, and a depth of denude zone of at least about 10, 20, 30, 40, 50, 70 or 100 micrometers can be obtained. In particular, the depth of the denude zone is essentially independent of the details of the electronic device fabrication method and does not depend on the external diffusion of oxygen that has traditionally been used. However, as a practical matter, the cooling rate required to obtain a shallow denude zone depth is rather extreme and thermal shock risks wafer breakage. Therefore, in another way, the thickness of the denude zone can be controlled by the choice of the atmosphere in which the wafer is annealed (see supra) while cooling the wafer at a less extreme rate. In other words, for a given cooling rate, a shallow denude zone (e.g., a deep denude zone (e.g., 50 microns or more), a medium depth denude zone (e.g., 30-50 microns) For example, an atmosphere that creates a template of less than about 30 microns, or without a denude zone, may be selected. With respect to these precise conditions for the annealing and cooling steps, it should be understood that other conditions than those described herein are also possible without departing from the scope of the present invention. In addition, these conditions can be determined experimentally, for example, by adjusting the temperature and annealing period and the ambient conditions (ie, the partial pressure of oxygen as well as the components of the atmosphere) to optimize the desired depth of t and / or t '. .

Although rapid thermal treatment used in the method of the present invention may cause a small amount of external diffusion of oxygen from the front and rear surfaces of the wafer, the amount of external diffusion is observed in conventional methods for the formation of the denude zone. Much less than. As a result, the ideal precipitation wafer of the present invention has a substantially uniform interstitial oxygen precipitation as a function of distance from the silicon surface. For example, prior to the oxygen precipitation heat treatment, the wafer is more preferably from the center of the wafer to a wafer region within about 15 microns at the silicon surface, preferably from a center of silicon to a wafer region within about 10 microns at the silicon surface, more preferably. Will have a substantially uniform interstitial oxygen concentration from the center of silicon to the region of the wafer within about 5 microns of the silicon surface, and most preferably from the center of the silicon to the region of the wafer within about 3 microns of the silicon surface. . In this context, a substantially uniform oxygen concentration means a change in oxygen concentration of about 50% or less, preferably about 20% or less, most preferably about 10% or less.

Typically, oxygen precipitation heat treatment does not cause a large amount of oxygen outward diffusion from the heat treated wafer. As a result, the concentration of interstitial oxygen in the denude zone at a distance of several microns or more from the wafer surface will not change significantly as a result of the precipitation heat treatment. For example, if the denude region of the wafer consists of a wafer region between the front side of the silicon and the distance D measured from the front side toward the center plane (which is at least about 10 micrometers), the distance from the silicon surface equal to D / 2. The oxygen concentration at a location within the dinude zone at will typically be at least about 75% of the highest concentration of interstitial oxygen concentration anywhere in the dinude zone. For any oxygen precipitation heat treatment, the interstitial oxygen concentration at this location will be greater by at least 85%, 90% or 95% of the maximum oxygen concentration anywhere in the denude zone.

E. epitaxial layer

In one embodiment of the invention, an epitaxial layer may be deposited on the surface of an ideal precipitated wafer. The aforementioned oxygen precipitate nucleation and stabilization method of the present invention may be performed before or after epitaxial deposition. Advantageously, the formation of stabilized oxygen precipitate nucleation centers allows the epitaxial deposition process to be performed without dissolving the precipitate profile formed.

The epitaxial layer will be formed by means known and used in the art, such as the decomposition of the silicon-containing mixture in gaseous state. In a preferred embodiment of the invention, the surface of the wafer is exposed to an atmosphere comprising volatile gas (eg, SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₃ Cl or SiH ₄ ) containing silicon. The atmosphere also preferably contains a carrier gas (preferably H ₂ ). In one embodiment, the source of silicon during epitaxial deposition is SiH ₂ Cl ₂ or SiH ₄ . If SiH ₂ Cl ₂ is used, the reactor vacuum pressure during deposition is preferably about 500 to 760 Torr. On the other hand, if SiH ₄ is used, the reactor pressure is preferably 100 Torr. Most preferred is when the source of silicon during deposition is SiHCl ₃ . This is much cheaper than other sources. In addition, epitaxial deposition using SiHCl ₃ can be carried out at atmospheric pressure. This is advantageous because there is no need for a vacuum pump and the reactor chamber does not have to be rigid to prevent destruction. Moreover, the risk of safety is smaller and the probability of air or other gas entering the reactor is smaller.

During epitaxial deposition, the wafer surface is maintained at a temperature sufficient to prevent the atmosphere comprising silicon from depositing polycrystalline silicon on the surface, that is, at least about 800 ° C., more preferably 900 ° C., and most preferably 1100 ° C. It is preferable to be. The growth rate of epitaxial deposition is preferably about 0.5 to about 7.0 μm / minute. The rate of about 3.5-4.0 μm / min is, for example, utilizing an atmosphere consisting essentially of about 2.5 mol% SiHCl ₃ and about 97.5 mol% H ₂ at a temperature of about 1150 ° C. and a pressure of about 1 atmosphere. Can be achieved.

If necessary, the epitaxial layer may further include a p-type or n-type dopant. For example, it is often desirable for the epitaxial layer to contain boron. Such a layer can be provided, for example, by including B ₂ H ₆ in the atmosphere during deposition. The mole fraction of B ₂ H ₆ in the atmosphere used to achieve the desired properties (e.g. resistivity) can be determined by several factors, e.g. the amount of out-of-boron diffusion from a particular substrate during the epitaxial deposition, as impurities. It depends on the amount of p-type and n-type dopants present in the reactor and the substrate, and the reactor pressure and temperature. For high resistivity applications, the dopant concentration in the epitaxial layer should be as low as practically possible.

F. Preparation of the Silicon on Insulator Structure

The stabilization of oxygen precipitated nuclei by nitrogen / carbon doping in accordance with the present invention can also be used to prepare a silicon on insulator (SOI) structure as disclosed in US Pat. No. 6,236,104, the contents of which are It is incorporated herein by reference. SOI structures can be created by subjecting a base or handle wafer to an ion implantation process that is standard in the art (see, eg, US Pat. No. 5,436,175). Preferably, an ideal wafer deposition process is performed on the handle wafer prior to ion implantation, whereby the oxide layer is located in the denude zone.

Alternatively, the SOI structure adheres the device layer wafer to a nitrogen / carbon doped stabilization handle wafer, and then a wafer thinning technique, also commonly used in the art. ) May be produced by etching away a portion of the device layer wafer (see, eg, US Pat. No. 5,024,723). Preferably, the device layer wafer will be bound to the handle wafer after the nitrogen / carbon doped handle wafer has undergone the ideal settling wafer treatment. Alternatively, however, the device layer wafer may first be bound to a nitrogen / carbon doped handle wafer and then subjected to an ideal settling wafer process for the entire SOI structure.

In addition to nitrogen / carbon stabilization, stabilization of the oxygen precipitate row formation center can be further increased by the thermal stabilization method disclosed in U.S. Patent Application No. 60 / 300,208, filed June 22,2001, The contents are incorporated herein by reference.

G. Measurement of Crystal Grid Bacon

* Measurement of crystal lattice vacancy in single crystal silicon can be performed by platinum diffusion analysis. In general, platinum is deposited on the sample and diffuses in the horizontal plane with a diffusion time and temperature selected such that the Frank-Turnbull mechanism dominates platinum diffusion but is sufficient to achieve steady state bacony decoration by the platinum atom. do. While 20 minutes of diffusion time and a temperature of 730 ° C. may be used for wafers with typical baconic concentrations in the present invention, more accurate tracking may be achieved at lower temperatures, eg, about 680 ° C. In addition, in order to minimize the possible effect of the silicided treatment, the platinum deposition method preferably results in a surface concentration of less than one monolayer. Platinum diffusion techniques are described, for example, in J. Appl. Phys. , Vol. 82, p. 182 (1997); "The Modeling of Platinum Diffusion In Silicon Under Non-Equilibrium Conditions," by Zimmermann and Ryssel, J. Electrochemical Society , Vol. 139, p. 256 (1992); "Vacancy Concentration Wafer Mapping In Silicon," Journal of Crystal Growth, Vol. 129, p. 582 (1993) by Zimmermann, Goesele, Seilenthal and Eichiner; "Investigation Of The Nucleation of Oxygen Precipitates in Czochralski Silicon At An Early Stage" by Zimmermann and Falster, Appl. Phys. Lett. , Vol. 60, p. 3250 (1992); And Appl . Phys. By Zimmermann and Ryssel . A , Vol. 55, page 121 (1992).

It is to be understood that the above description is for illustrative purposes only and not limitation. Many other embodiments will occur to those skilled in the art upon reading the above description. Therefore, the scope of the present invention should not be determined solely by the above description, but should be determined by the claims and the equivalents of the claims.

The above arrangement according to the present invention is directed to providing a single crystal silicon wafer which essentially forms an oxygen precipitate with an ideal non-uniform depth distribution during the heat treatment cycle of any electronic device manufacturing process; Providing a single crystal silicon wafer that optimally and reproducibly forms oxygen deposits of sufficient depth in the denude zone and wafer bulk; Providing a single crystal silicon wafer in which the formation of the denude zone and the formation of oxygen precipitates in the wafer bulk do not depend on the oxygen concentration difference in these areas of the wafer; Providing a single crystal silicon wafer whose thickness of the resulting denude region is essentially independent of the details of the integrated circuit fabrication process sequence; The formation of the denude zone and the formation of oxygen precipitates in the wafer bulk are not affected by the thermal history and oxygen concentration of the monocrystalline silicon ingot grown by the Czochralski method in which the silicon wafer is sliced. Providing a silicon wafer; Providing a process in which the formation of the denude zone does not depend on the external diffusion of oxygen; And silicon is doped with nitrogen and / or carbon in sufficient concentration to stabilize the oxygen precipitate necleation center to withstand subsequent rapid heat treatment without disturbing the formation of the denude zone. Provide the same effect.

Claims (2)

Two roughly parallel major faces, one major face being the front face of the wafer and the other major face being the back face of the wafer, the central face between the front and back faces, and the peripheral edge joining the front and back faces. In the provided single crystal silicon wafer, When the dopant-nitrogen selected from the group consisting of nitrogen and carbon is a dopant, the concentration of nitrogen has a value of about 1 × 10 ¹² atoms / cm 3 to about 5 × 10 ¹⁴ atoms / cm 3, and when carbon is a dopant, The concentration has a value between about 1 × 10 ¹⁶ atoms / cm 3 and about 4 × 10 ¹⁷ atoms / cm 3; A surface layer comprising an area of the wafer between the front face and the distance D measured from the front face toward the center face, the surface layer having no stabilized oxygen precipitate nucleation center; A bulk layer comprising a second wafer region between a midplane and a surface layer, the bulk layer comprising a stabilized oxygen precipitate nucleation center. A method of making a single crystal silicon wafer having a controlled oxygen precipitation aspect, Front layer, center surface sliced from Czochralski grown single crystal silicon ingot and including wafer area between front, back, center plane between front and back, and the distance D measured from front to center A bulk layer comprising a wafer region between and the front layer, and a dopant selected from the group consisting of nitrogen and carbon—when the nitrogen is the dopant, the concentration of nitrogen is from about 1 × 10 ¹² atoms / cm 3 to about 5 × 10 Selecting a wafer having a value of ¹⁴ atoms / cm 3 and when the carbon is the dopant, the concentration of carbon has a value of about 1 × 10 ¹⁶ atoms / cm 3 to about 4 × 10 ¹⁷ atoms / cm 3 Making a step; Heat treating a wafer to form crystal lattice vacancy in the front layer and the bulk layer; Cooling the heat-treated wafer at a rate to form a vacancy concentration profile in the wafer—in the vacancy concentration profile, the highest density of bacony is present in the bulk layer and the concentration is determined from the position of the highest density of the wafer. It generally decreases toward the front direction, and the difference in bacon concentration in the front and bulk layers is such that the stabilized oxygen precipitate nucleation center is not formed in the front layer and the stabilized oxygen deposit nucleation center is formed in the bulk layer. Having a size; When the heat-treated wafer is cooled, forming a stabilized oxygen precipitate nucleation center in the bulk layer, wherein the concentration of the stabilized oxygen precipitate nucleation center in the bulk layer depends primarily on the concentration of baconcies. Method of manufacturing a single crystal silicon wafer.

Images