JPH1192283A - Silicon wafer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an oxygen concentration on the surface layer of a substrate and to increase fine oxygen precipitation defects having IG effects in a deep zone, by annealing a wafer cut out from a silicon single crystal ingot, ground and polished in a gas atmosphere having a specific heat capacity higher than hydrogen at a specific temperature. SOLUTION: A process for annealing a silicon wafer has 800-1,500 deg.C annealing temperature and uses a gas having a heat capacity higher than at least hydrogen, preferably >=29 J/mol heat capacity at a room temperature as an atmosphere gas. Preferably an ammonia gas or a nitrogen gas is used as the gas for satisfying the conditions. This method for producing a silicone wafer is applied to a single crystal wafer produced by using a quartz crucible by a CZ method to show great effects. The silicon wafer produced by the method has <=10<17> atoms/cm<3> oxygen concentration in a surface layer from about 2 μm from the surface and functions as a getter of impurity having formed an oxygen precipitated substance and BMD in a deep layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor substrate and a method for manufacturing the same, and more particularly, to a silicon wafer used as a substrate for various ICs or LSIs and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, a silicon (Si) wafer cut from a single crystal ingot manufactured by a pull-up (CZ: Czochralski) method is mainly used as a substrate for a semiconductor device such as an LSI. The CZ method uses a polycrystalline S
In this method, i is melted, a seed crystal is immersed in the melt, and the seed crystal is gradually pulled up while rotating slowly to grow the crystal.

[0003] Single crystal ingots produced by the CZ method are:
Further, it is processed into a Si wafer through the following steps. First, the single crystal ingot is cut into several blocks as a whole, and each block is subjected to surface grinding to obtain a predetermined outer diameter. Next, orientation flat processing is performed on a predetermined surface in the state of the block. Thereafter, the block is cut into a wafer by a disk-shaped diamond cutter. The cut wafer is wrapped on both sides and processed to take the corners of the edges.

[0004] In the lapping process, a processing strain is easily generated in a wafer.
Etching of the wafer surface is performed for about several tens μm. Then, in order to improve the smoothness of the wafer surface, the wafer is mirror-polished using an abrasive, and final cleaning is performed.

In the CZ method, since a quartz crucible is used, oxygen is dissolved from the quartz crucible into a molten crystal. Therefore, oxygen is contained in the Si wafer obtained by the above-described method at 5 × 10 ^{17 to} 1.8 × 10 ¹⁸ atoms / c.
It can not be avoided be incorporated about m ^3.

[0006] The concentration of the mixed oxygen is 1200 ° C to 1300 ° C.
At lower temperatures, it is in a supersaturated state, corresponding to the solid solubility limit in ° C., and most of the oxygen exists between the lattices of the single crystal. These supersaturated oxygen atoms form micro defects such as oxygen precipitates and dislocations during the LSI manufacturing process, and also cause the occurrence of dislocations at the pattern edge due to oxygen-induced stacking faults (OSF).

In a shallow layer of about 2 μm from the wafer surface,
A so-called “active region” in which various thin-film devices such as transistors and diodes operate is formed. When micro defects, OSFs or dislocations caused by supersaturated oxygen are formed in this active region, junction leakage increases. And the retention time of the memory is deteriorated, thereby lowering the yield of the device.

Therefore, in order to increase the yield of the device, it is desired to reduce at least the concentration of the mixed oxygen in the active region as much as possible.

The concentration of oxygen impurities in a single crystal ingot produced by the CZ method is usually not uniform and has a different concentration distribution depending on a place. Therefore, conventionally, a portion having a low concentration of mixed oxygen is conventionally selected from ingots produced. They were also cut out and used.

[0010]

However, since a single crystal ingot produced by the CZ method contains 10 ¹⁷ atoms / cm ³ or more even in a portion where the concentration of mixed oxygen is relatively low, it is selectively cut out. The method cannot sufficiently eliminate the effect of oxygen contamination.

[0011] Therefore, recently, Si wafers were placed in hydrogen for 1 hour.
Perform annealing at a temperature of about 000 ° C to 1200 ° C
A method is being considered. This high-temperature hydrogen annealing
Can greatly reduce the concentration of oxygen in the wafer surface.
Can be.

On the other hand, the problem in the active region on the surface of the wafer is not limited to that caused by the oxygen contained in the wafer itself. In the process of manufacturing LSIs on wafers, contamination of new wafers occurs in each process,
Various impurities can enter the active region.

Recently, a wafer gettering technique has been studied as one method for addressing this problem. The wafer gettering technique refers to a technique in which crystal defects and processing strain are formed in a region deeper than the active region of the wafer, and these crystal defects and the like are used as getters for impurities mixed into the active region. That is, this is a technique for providing the wafer itself with an impurity gettering function.

According to the gettering technique, it is possible to remove impurities in the active region and to suppress the occurrence of various defects in the active region that cause a malfunction of the device. Note that among gettering techniques, one that uses a crystal defect due to crystal precipitation or the like as a getter is particularly called intrinsic gettering (IG), and such an effect is called an IG effect.

That is, a wafer having a low impurity concentration in a wafer surface layer serving as an active region of an element and sufficiently including a crystal defect having an IG effect in a region deeper than the active region is obtained by LS.
Desirable as a semiconductor substrate for manufacturing I.

The above-described high-temperature hydrogen annealing of the wafer can reduce the oxygen concentration in the surface layer of the substrate, and also has a micro oxygen precipitation defect (BMD: Bulk Micro) having an IG effect in a region deeper than the active region. Defect) can be formed.

It is an object of the present invention to reduce the concentration of mixed oxygen in the substrate surface layer corresponding to the active region, and to form more and more efficiently fine oxygen precipitation defects of oxygen having an IG effect in a region deeper than the active region. An object of the present invention is to provide a method of manufacturing a silicon wafer and a higher quality silicon wafer manufactured by the method.

[0018]

The first method of manufacturing a silicon wafer according to the present invention is characterized in that at least a step of manufacturing a single crystal ingot, a step of cutting a wafer from the single crystal ingot, and a step of grinding or grinding the wafer. In a method for manufacturing a silicon wafer having a step of polishing and a step of annealing the wafer, the step of annealing the wafer is performed at an annealing temperature of 800 ° C. to 1500 ° C.
And using a gas having a heat capacity higher than at least hydrogen as the atmospheric gas.

According to the first feature, in the shallow layer corresponding to the active region on the surface of the wafer, the oxygen concentration can be reduced to the same extent as in the case of annealing in a hydrogen gas atmosphere, and the active region of the wafer can be reduced. For deep layers, IG
More minute oxygen precipitation defects (BMD) exhibiting the effect can be formed. It is considered that even when annealing is performed under the same temperature conditions, if the heat capacity of the atmosphere gas is high, the temperature rise rate of the actual temperature of the wafer is slowed down, and the growth of oxygen precipitates that generate BMD is promoted.

The second method of manufacturing a silicon wafer according to the present invention is characterized in that, in the method of manufacturing a silicon wafer having the first characteristic, the atmosphere gas has a heat capacity of at least 29 J / molK at room temperature (298 K). Is used.

According to the second feature, since the heat capacity of hydrogen gas is 28.836 J / molK at room temperature, if a gas having a heat capacity of 29 J / molK or more can be used, a gas having a higher heat capacity than hydrogen gas is used. As a result, the oxygen concentration can be reduced in the shallow layer corresponding to the active region on the wafer surface to the same extent as in the case of the annealing treatment in the hydrogen gas atmosphere. Oxygen precipitates accompanying BMD exhibiting an effect can be generated more.

The third method of manufacturing a silicon wafer according to the present invention is characterized in that, in the method of manufacturing a silicon wafer having the above-described first or second characteristic, when the annealing temperature is set, 3 ° C./min to 1000 ° C. / Heating is performed at a set heating rate of min.

According to the third aspect, the effect of the first or second aspect can be ensured without lowering the productivity by limiting the heating rate.

The method for manufacturing a silicon wafer having the first to third characteristics is particularly effective when the step of manufacturing the single crystal ingot is performed by using the CZ method. The CZ method uses a quartz crucible,
Oxygen is easily mixed from this crucible into the crystal ingot,
This is because the concentration of mixed oxygen in the wafer is high and the demand for oxygen removal is high.

Ammonia gas or nitrogen gas may be used as the atmosphere gas satisfying the first feature or the second feature.

A feature of the silicon wafer of the present invention is a wafer manufactured by any one of the above-described manufacturing methods of the present invention, wherein the oxygen concentration in a surface layer having a depth of about 2 μm from the wafer surface is 10 ¹⁷ atoms / s. cm ³ or less.

If the oxygen concentration can be kept within the above range, it is possible to suppress the occurrence of defects such as device malfunction due to oxygen impurities.

Another feature of the silicon wafer of the present invention is that the feature of the first silicon wafer is the same as that of the first silicon wafer.
MD density is 10 ⁷ to 10 ¹⁰ / cm ³ or oxygen concentration of oxygen precipitate is 1 × 10 ¹⁴ to 1 × 10 ¹⁸ atoms / c
m ³ .

Since a low oxygen concentration is ensured in the active region on the wafer surface, oxygen precipitates due to oxygen and the BMD formed therewith are mainly formed in a layer deeper than the active region. It can function as a getter for impurities mixed into the active layer.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION First, according to the present invention, an Si wafer is annealed in three types of conventionally used atmosphere gases including hydrogen, and the influence of the annealing atmosphere gas on the oxygen concentration in the Si wafer. Was analyzed and examined. Hereinafter, the examination contents and examination results will be described.

(Study Example 1) First, an annealing process was performed on a Si wafer using hydrogen (H ₂ ), which has been studied conventionally, as an atmospheric gas.

The used Si wafer is a p-type wafer having a plane orientation of (100) produced by cutting a single crystal ingot produced by the CZ method and producing it by a conventional method. The wafer diameter was 150 mmΦ, and the average oxygen concentration in the substrate before the annealing treatment was 7 × 10 ¹⁷ atoms / cm ³ .

The wafer was placed in a quartz furnace replaced with hydrogen gas, and the inside of the furnace was gradually heated at a constant speed using an external heater capable of controlling a temperature. The pressure of the hydrogen atmosphere in the furnace was normal pressure.

FIG. 1 is a graph showing the temperature setting conditions of the heater used. The horizontal axis represents time, and the vertical axis represents furnace temperature. As shown in FIG.
The temperature was raised to about ° C, and the wafer was loaded into the furnace at the point indicated by A in the figure. Next, when the temperature reaches a constant 600 ° C. (point B in the figure), the furnace temperature is raised to 1000 ° C. at a constant heating rate of 3 ° C./min, and reaches 1000 ° C. (in the figure). (C point) to maintain the temperature for one hour,
The wafer was annealed. After that (point D in the figure)
The furnace temperature was lowered to 800 ° C. at a rate of 3 ° C./min. When the temperature in the furnace became constant at 800 ° C. (point F in the figure), the wafer was taken out of the furnace.

The oxygen concentration of the Si wafer after the annealing was measured by using secondary ion mass spectrometry (SIMS). SIMS uses Fourier Transform Infrared Spectroscopy (FTIR)
The sensitivity is higher than that of, and analysis in the depth direction is also possible.

FIG. 2 is a graph showing the distribution of oxygen concentration in the depth direction obtained by SIMS. In the figure, the depth from the wafer surface is shown in μm in the horizontal axis direction, and the oxygen concentration in the substrate is shown in the number of atoms per unit volume (atoms / atoms) in the vertical axis direction.
cm ³ ).

As shown in the figure, in the surface layer of the wafer in which the active region of the device is formed, the oxygen concentration decreases rapidly nearer to the surface. It shows that it was done in a targeted manner. This time, the precise SIMS measurement performed by the present inventors revealed that the oxygen concentration in the outermost surface layer of the wafer was 2 × 10 ¹⁶ atoms.
It was confirmed that the value reached an extremely low value of s / cm ³ .

On the other hand, in a layer deeper than the active region having a depth of 20 μm to 50 μm, several spike-like peaks appeared on the graph. These peaks indicate the presence of oxygen precipitates. The oxygen precipitate concentration determined by SIMS measurement was 1 × 10 ¹⁴ to 1 × 10 ¹⁸ atoms / cm ³ . These oxygen precipitates have a small oxygen precipitation defect (B
MD), the BMD density was 1 × 10 ⁷ to 1 × 10 ¹⁰ particles / cm ³ as measured by infrared scattering tomography.
Was confirmed.

As described above, it has been confirmed that the BMD exhibiting the IG effect can be formed in a layer deeper than the active region of the substrate by annealing in hydrogen. According to the experience of the inventors, it is known that oxygen precipitates are less likely to be generated when the temperature rise rate in the furnace is set too high.

(Study Example 2) Next, the Si wafer was annealed using argon (Ar) gas as an atmospheric gas. As the conditions other than the atmosphere gas, the same conditions as those described in Study 1 described above were used. That is, the used Si wafer was cut out from a single crystal ingot produced by the CZ method, and was a p-type wafer having a plane orientation of (100). The average oxygen concentration in the substrate before the annealing treatment was the same as that used in Study 1, and was 7 × 10 ¹⁷ at.
oms / cm ³ .

The wafer was placed in a quartz furnace replaced with Ar gas, and the inside of the furnace was gradually heated at a constant speed using an external heater. As the temperature adjustment sequence of the heater used, the conditions shown in FIG. That is, 3 ° C / m
The furnace temperature was raised to 1000 ° C. at a constant rate of temperature increase in, and maintained at that temperature for 1 hour, and then the furnace temperature was lowered to 800 ° C. at a rate of 3 ° C./min.

The oxygen concentration of the Si wafer after the annealing was measured using SIMS. FIG. 3 shows the measurement results. The units in the graph are the same as in FIG.

As shown in the graph, in the surface layer of the wafer on which the active region of the device is formed, the oxygen concentration decreases rapidly nearer to the surface, as in the case where the annealing treatment is performed in a hydrogen atmosphere. The oxygen concentration in the outermost surface layer of the wafer was the same level as 2 × 10 ¹⁶ atoms / cm ³ . Thus, Ar gas, which is an inert gas, is used as the atmosphere gas.
It has been found that even in the case of using, the annealing treatment can effectively remove oxygen from the wafer surface layer.

However, in the same graph, the depth 2
In the region from 0 μm to 50 μm, a peak corresponding to an oxygen precipitate as appeared in the case of annealing in a hydrogen atmosphere was not observed.

(Study Example 3) Finally, the Si wafer was annealed using ammonia (NH ₃ ) gas as the atmospheric gas. Except for the atmosphere gas, the same conditions as those described in the above-described Study 1 and Study 2 were used. That is, the used Si wafer was cut out from a single crystal ingot manufactured by the CZ method, and the plane orientation (100)
Is a p-type wafer. The average oxygen concentration in the wafer before annealing was 7 × 1 as in the case of the study 1.
It was 0 ¹⁷ atoms / cm ³ .

The wafer is placed in a quartz furnace replaced with NH ₃ gas, and the furnace temperature is raised to 100 ° C. at a constant rate of 3 ° C./min.
Raise to 0 ° C, maintain the temperature for 1 hour, then 3 ° C
The furnace temperature was lowered to 800 ° C. at a rate of / min, and when the furnace temperature became constant at 800 ° C., the wafer was taken out of the furnace.

The oxygen concentration of the Si wafer after the annealing was measured using SIMS. FIG. 4 shows the measurement results. The units in the graph are the same as in FIGS.

As shown in the graph, hydrogen atmosphere, Ar
As in the case where the annealing treatment is performed in the atmosphere, in the surface layer of the wafer where the active region of the device is formed, the oxygen concentration decreases rapidly nearer to the surface. The level reached a sufficiently low level of × 10 ¹⁶ atoms / cm ³ . It was found that even when NH ₃ was used as the atmosphere gas, the annealing process could effectively remove oxygen from the wafer surface layer.

In a layer having a depth from the wafer surface of 20 μm to 50 μm and deeper than the active region, many spike peaks indicating oxygen precipitates were observed on the graph. NH
Wafers annealed in a ₃ gas atmosphere are more IG than substrates annealed in a conventional hydrogen atmosphere.
The effect was confirmed to be high.

Incidentally, when the nitrogen concentration from the wafer surface to the depth of 100 μm was measured, it was 5 × 10 ¹⁵ atoms /
The value was as low as cm ³ .

From the results of the above studies 1 to 3, the following can be inferred as the influence of the atmosphere gas during the annealing process. First, the effect of removing oxygen on the outermost surface of the wafer in which the active region of the device is generated has a small dependence on the type of atmospheric gas during the heat treatment.
Regardless of the reactivity, such as whether the atmosphere gas is a strong reducing gas or an inert gas, the oxygen concentration distribution near the wafer surface, that is, the outward diffusion concentration distribution of oxygen, hardly depends on the atmosphere gas.

On the other hand, in the formation of oxygen precipitates in a deep region exceeding 20 μm from the wafer surface, a clear difference is recognized among the three kinds of atmosphere gases of hydrogen, argon, and ammonia. If these atmosphere gases are arranged in the order of the ease of forming oxygen precipitates, the order is ammonia>hydrogen> argon.

The present inventors have found that this order corresponds to the magnitude of the heat capacity of these atmospheric gases. The heat capacity of each gas at room temperature (298K) is NH
₃ 35.100J / molK, H ₂ is 28.836J /
molK and Ar are 20.786 J / molK.

The relationship between the oxygen precipitate and the heat capacity of the atmospheric gas will be considered as follows.

The actual temperature of the Si wafer that has been annealed in the furnace (hereinafter referred to as the actual temperature) does not match the temperature condition shown in FIG. 1 and is affected by the heat capacity of the atmosphere gas. . That is, if the heat capacity of the atmosphere gas is large, the actual temperature rise rate and the temperature decrease rate of the actual temperature of the boundary layer around the Si wafer become slower, and as a result, the actual temperature increase rate and the temperature decrease rate of the Si wafer become Should be slow.

Whether the precipitate nucleus of oxygen existing inside the silicon wafer grows or disappears as a precipitate usually depends on the radius of the precipitate nucleus. When the radius of the precipitation nucleus exceeds a certain critical radius, the precipitated atoms adhere to the nucleus and grow as precipitates,
It is known that the precipitation nuclei disappear when the radius of the precipitation nuclei does not reach the critical radius.

The precipitation nuclei tend to grow larger as the heating rate is slower. If a gas having a larger heat capacity is used as the atmosphere gas, the heating rate at the actual temperature of the Si wafer becomes slower, and the critical radius increases. It is considered that precipitation nuclei exceeding the above range are easily generated.

The oxygen concentration in the wafer surface layer is
It has already been pointed out that it does not depend much on the type of atmosphere gas at the time of annealing, but the result of measuring the defect density of the wafer surface layer using the X-ray topography method shows that the defect density is the highest when heat treatment is performed in an ammonia atmosphere. It was confirmed that the number of defect densities was large, followed by Ar and H ₂ in that order. Also in this case, it is preferable to anneal in a gas atmosphere having a large heat capacity because the effect of reducing the defect density is high.

Hereinafter, an embodiment of the method for manufacturing a Si wafer according to the present invention will be described based on the above-described examination results.

(Embodiment) First, an Si wafer having been subjected to mirror polishing and final cleaning by a conventional method is prepared. The Si wafer to be used is not particularly limited as to which manufacturing method the original single crystal ingot is manufactured, but is particularly effective for a wafer obtained by cutting a single crystal ingot manufactured by the CZ method in which the amount of mixed oxygen is a problem. It is.

The annealing furnace to be used is an 800 furnace such as a quartz furnace.
A material that can be heated at a high temperature of about 1500C to about 1500C and that can control the temperature rising rate and the ultimate temperature is used. Further, it is preferable to use a gas exhaust unit, a supply unit, and a sealing unit so that the inside of the annealing furnace can be replaced with a predetermined gas.

First, a Si wafer is carried into an annealing furnace while being housed in a carrier made of quartz or the like.

Next, the inside of the annealing furnace is replaced with a predetermined gas. As the predetermined gas, for example, NH ₃ used in Study 3 described above is used. Room temperature (298K) besides NH ₃
If a gas having a heat capacity of 29 J / molK or more, that is, a gas having a heat capacity larger than at least H ₂ gas is used, N
An effect similar to or higher than that of H ₃ can be obtained. For example, the heat capacity at room temperature is 29.124 J / m
olK nitrogen (N ₂ ), 29.200 J / molK hydrogen iodide (HI), 35.4 J / molK formaldehyde (HCHO), 35.3 J / molK methane (CH ₄ ), 43.9 J / molK Acetylene (C ₂ H
₂ ) etc. can be used. Preferably, 30
J / molK or more, more preferably 40 J / mol
Use a gas of K or more.

It is to be noted that not only a single gas but also a mixed gas which has a high heat capacity as an average of the whole atmosphere gas may be used. Therefore, for example, a gas having a high heat capacity may be mixed with H ₂ to form an atmospheric gas.

Thereafter, heating in the annealing furnace is started.
In addition, as performed in Study 1 to Study 3, 600 ° C.
The temperature in the furnace may be maintained to a certain extent, and the time required for raising the temperature may be shortened. Gradually increase the furnace temperature to the annealing temperature. The annealing temperature at this time is in the range of 800 ° C to 1500 ° C,
For example, the temperature is set to 1000 ° C. If the annealing temperature is lower than 800 ° C., the effect of removing oxygen from the wafer surface layer cannot be sufficiently obtained. On the other hand, if the annealing temperature exceeds 1500 ° C., the thermal load on the device is large, which is not preferable.

The rate of temperature rise is preferably at least 3 ° C./min from the viewpoint of increasing productivity. However, if the heating rate is too fast, it becomes difficult for oxygen precipitates to grow in a deep region of the wafer, and the generation of getters may be insufficient. Therefore, the heating rate is about 3 ° C./min.
It is preferable to set it to １０００1000 ° C./min.

When the temperature reaches the annealing temperature, the temperature is maintained for a certain time. The annealing time is not particularly limited,
The selection is made in a range of several minutes to several hours in consideration of annealing temperature conditions and the like.

When the annealing process is completed, the temperature in the annealing furnace is gradually lowered. The cooling rate is, for example, about 3 ° C.
/ Min.

According to the above-described annealing treatment, as in the case of the annealing treatment conventionally performed in the H ₂ atmosphere gas, about 2 μm from the surface of the substrate on which transistors and diodes are formed.
In the active region of about μm, the oxygen concentration is set to 5 × 10 ^{16 at}
ms / cm ³ or less.

Further, since a gas having a large heat capacity is used as the atmosphere gas instead of H ₂ which has been conventionally used as the atmosphere gas, the rate of temperature increase of the actual temperature of the Si wafer is suppressed,
An environment in which an oxygen precipitation nucleus exceeding a critical radius is easily grown in a region deeper than the active region is formed, and an oxygen precipitate can be grown. Oxygen precipitates are accompanied by the generation of minute oxygen precipitation defects (BMD) exhibiting the IG effect, and 1 × 10 ⁷ -1
A BMD of × 10 ¹⁰ pieces / cm ³ can be formed.

Further, from the active region of the substrate surface layer to the deep region beyond the active region, the defect density containing impurities other than oxygen can be reduced. Also, the nitrogen concentration was 1 × 10 ¹⁶ over a range of 100 μm in depth from the wafer surface.
atoms / cm ³ or less.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to these embodiments. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0073]

As described above, the method of manufacturing a silicon wafer according to the present invention includes a step of annealing a wafer cut from a single crystal ingot.
The temperature is set to 00 ° C. to 1500 ° C., and a gas having a heat capacity higher than that of hydrogen is used as an atmosphere gas. In the shallow layer corresponding to the active region on the wafer surface, the oxygen concentration is almost the same as that in the annealing process in the hydrogen gas atmosphere. In the region deeper than the active region of the wafer, more oxygen precipitates can be formed, and the BMD density for exhibiting the IG effect can be increased.

Therefore, it is possible to provide a high-quality Si wafer capable of always maintaining a low concentration of oxygen and other impurities in an active region of a wafer which is an operation region of various devices.

By using the Si wafer manufactured by the above method, the yield of semiconductor devices can be improved.

In addition, the method of the present invention described above can be carried out in a simple process with a small burden on the process, so that no burden is imposed on the process cost, and the method is highly practical.

[Brief description of the drawings]

FIG. 1 is a graph showing annealing temperature conditions used in Study 1 to Study 3 according to an embodiment of the present invention.

FIG. 2 is a graph showing a depth direction distribution of oxygen concentration in a Si wafer that has been annealed in an H ₂ atmosphere.

FIG. 3 is a graph showing a depth direction distribution of oxygen concentration in a Si wafer that has been annealed in an Ar atmosphere.

FIG. 4 is a graph showing a depth direction distribution of oxygen concentration in a Si wafer that has been annealed in an NH ₃ atmosphere.

Claims (7)

[Claims] 1. A silicon wafer manufacturing method comprising: at least a step of producing a single crystal ingot; a step of cutting out a wafer from the single crystal ingot; a step of grinding or polishing the wafer; and a step of annealing the wafer. 3. The method for manufacturing a silicon wafer according to claim 1, wherein the step of annealing the wafer comprises: setting an annealing temperature to 800 ° C. to 1500 ° C .; and using a gas having a heat capacity higher than at least hydrogen as an atmosphere gas. 2. The method according to claim 1, wherein a gas having a heat capacity of at least 29 J / molK at room temperature is used as the atmosphere gas. 3. An annealing temperature is set at 3 ° C./mi.
The method for manufacturing a silicon wafer according to claim 1, wherein the wafer is heated at a set temperature increase rate of n to 1000 ° C./min. 4. The method for producing a silicon wafer according to claim 1, wherein the step of producing the single crystal ingot is a step of producing using a pulling method. 5. The method for manufacturing a silicon wafer according to claim 1, wherein the atmosphere gas is ammonia gas or nitrogen gas. 6. A silicon wafer manufactured by the manufacturing method according to claim 1, wherein an oxygen concentration at a depth of about 2 μm from the surface of the silicon wafer is 10 ¹⁷ atoms / cm ³ or less. A silicon wafer, characterized in that: 7. The density of minute precipitation defects of oxygen in the silicon wafer is 10 ⁷ to 10 ¹⁰ / cm ³ , or the oxygen concentration of the oxygen precipitate is 1 × 10 ¹⁴ to 1 × 10 ¹⁸ atoms / c.
7. The silicon wafer according to claim 6, wherein m ³ is m ³ .