JPH046196A - Silicon wafer and production thereof - Google Patents

Abstract

PURPOSE:To prevent the generation of the warp of a silicon wafer with a heat treatment during a device stage by incorporating sulfur, tin or lead at a specific concn. into the silicon wafer. CONSTITUTION:The sulfur within a 5X10<15> to 3X10<16> atoms/cm<2> range or the tin or lead within a 5X10<15> to 5X10<19> atoms/cm<2> range is incorporated into the silicon wafer. The silicon single crystal body for obtaining such silicon wafer is obtd. by the following method: Namely, any of the sulfur tin or lead is added together with silicon raw materials into a melt and the concn. of the sulfur in the melt in the section in a crucible where the silicon single crystal is pulled up is set at the value within + or -20% of the value obtd. by dividing the concn. of the sulfur in the above-mentioned wafer by the segregation constant Ks of the sulfur for the silicon; or the concn. of the tin or lead is set at the value within + or -20% of the value obtd. by dividing the concn. of the tin or lead in the above-mentioned wafer by the segregation constant Ksn or Kpb of the tin or lead for the silicon. Further, the concn. of the sulfur, tin or lead in the section where the silicon single crystal body is pulled up is controlled to the above-mentioned value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a silicon wafer and a method for manufacturing the same. More specifically, the present invention relates to a silicon wafer that is excellent in strength and is less likely to warp during a device process, and a method for manufacturing the same.

[Prior Art] In device processes and the like, wafers are heated to high temperatures when diffusing impurities into silicon crystals or forming oxide films on their surfaces, but a temperature distribution occurs within the wafer during this process. Stress is generated by this temperature distribution, and when the stress value is large, dislocations called thermal stress dislocations occur. When thermal stress dislocation occurs, the wafer tends to warp.

Furthermore, in recent years, as demand for silicon wafers has increased and device manufacturers have sought to increase their productivity, increasing the diameter of silicon wafers has led to the generation of the thermal stress described above. The problem of wafer warpage becomes more and more serious.

If a wafer warps, it will reduce the resolution of lithography and reduce the product yield when microfabrication is applied to the wafer surface using photoetching technology in the device process, so it is necessary to prevent this as much as possible. It is desirable to prevent this.

Conventionally, wafers manufactured by the Czochralski method (CZ method), in which crystals are pulled from a melt in a crucible while growing them, have been widely used as silicon wafers for manufacturing semiconductor devices such as ICs and LSIs. Silicon wafers manufactured by this method are compared to wafers obtained by the floating zone method (FZ method) because the oxygen atoms dissolved into the silicon melt from the quartz crucible are doped into the crystal. The high content of oxygen atoms is the main reason why wafers obtained by the CZ method are widely used.

In other words, oxygen in the silicon crystal precipitates at dislocations and has the function of blocking the movement of dislocations [Imai, M., an
dSumino, K., “In-5itu X-r
ay Topographic 5tudyofTh
e Dislocation Mobility in
lligh-Purity and Impurity
-Doped 5ilicon Cystals,”
Ph11. Mag,, Vol, A47. pp5
99-621 (1983), the propagation of dislocations due to thermal stress is less likely to occur and the occurrence of warpage of the weno\ is reduced. Furthermore, oxygen in the silicon crystal forms microdefects as precipitates and is also useful in gettering impurities such as heavy metals. This intrinsic gettering using oxygen is a technique widely used in the manufacture of semiconductor integrated circuits. However, if a large number of micro-defects exist inside the crystal, dislocations will multiply based on the micro-defects when thermal stress is applied, making the wafer more likely to warp.

From this point of view, in silicon wafers obtained by the CZ method, it has not been expected to prevent wafer warping to within 1 minute only by controlling the oxygen concentration.

Furthermore, as a method to prevent wafer warping, we have developed a technology that reduces the thermal stress applied to wafers during the device process.
For example, there is a ramping method in which a wafer is first inserted into a low-temperature furnace and then the temperature of the furnace is raised, and there are also techniques to improve the strength of silicon wafers, such as adding Ge to silicon crystals. Although it has been proposed,
None of them have reached the point where sufficient effects can be obtained.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to provide a silicon wafer with high tensile strength and a method for manufacturing the same in which warping of the wafer is less likely to occur due to heat treatment during a device process.

[Means for solving the problem] The above objectives are 5 x 1015 to 3 x 1011'
Sulfur in the range of atoms/cm3, 5 x 1015 to 5
Tin in the range of x 101019ato/cm3 or 5 x 1015 to 5 x 1019atoms/
This is achieved by a silicon wafer characterized by a lead content in the range of cm3.

The above objects are further achieved in a method of pulling and growing a silicon single crystal from a silicon melt formed in a crucible. In the melt at the site where the silicon single crystal is pulled, the sulfur concentration is set to 5 x 1015 to 3 x 1016 atOIIls in the single crystal.
Set the desired sulfur concentration within the range of /cm3 to a value within ±20% of the value obtained by dividing the sulfur segregation coefficient kS to silicon, or set the tin or lead concentration to a value of 5 × 1015 to 5 in the single crystal. ×1019atoIIls/cm
The desired tin or lead concentration within the range of 3 is set to a value that is within ±20% of the segregation coefficient kSn of tin or lead to silicon or the value divided by ・ゎ, and the single crystal pull-F A portion of the crucible that pulls the silicon single crystal by continuously or intermittently replenishing the raw material to a portion of the crucible that pulls the silicon single crystal according to the amount of the silicon single crystal that is pulled up through the single crystal pulling operation. This can also be achieved by a method for manufacturing a silicon single crystal, characterized in that the concentration of sulfur, tin, or lead in the melt is controlled within the predetermined range.

[Function] The silicon wafer of the present invention is characterized in that it contains trace amounts of sulfur, tin, or lead within the ranges described above.

Sulfur, tin, and lead elements all have different atomic radii from silicon atoms, so when these atoms are added to a silicon single crystal, a strain field is formed in the silicon single crystal. When a strain field is formed in this way, dislocations are difficult to move even in a stress field at a high temperature, such as during heat treatment in a device process, and the silicon wafer is difficult to warp.

In addition, FIGS. 3 to 5 show that the present inventors actually added sulfur, tin, or lead to silicon wafers, and produced a plurality of silicon wafers each with different concentrations.
This wafer was heated at 800°C in a dry02 atmosphere for 1
Heat treatment at 1000°C for 10 hours in a dry02 atmosphere, then inserted into a furnace maintained at 1000°C in a dry02 atmosphere at a speed of 90cm/min, held for 20 minutes, and then taken out at a speed of 90cm/min. FIG. 3 is a diagram showing the relationship between the concentration of sulfur, tin, or lead in the wafer and the magnitude of warpage when performing the above.

Furthermore, in the method for manufacturing a silicon single crystal of the present invention,
First, sulfur, tin, or lead is added to the melt together with the silicon raw material, and the sulfur, tin, or The concentration of lead is determined by changing the desired concentration in the single crystal body to the segregation coefficient of sulfur, tin or lead to silicon, kS, k5. , or set to a value within a predetermined range from the value divided by kpb, start single crystal pulling, and then,
Depending on the amount of single crystal pulled, the concentration of sulfur, tin, or lead in the melt at the part of the crucible where the silicon single crystal is pulled is adjusted while continuously or intermittently replenishing raw materials. A single crystal is grown by controlling the concentration within the set concentration range. For this reason, the concentration of sulfur, tin, or lead in the melt at the point where the silicon single crystal is pulled in the crucible increases, even though the concentrations of sulfur, tin, or lead increase due to the segregation of these elements during single crystal growth. The concentration of these added elements is controlled within the predetermined range through the operation, and therefore, in the single crystal obtained, fluctuations in the concentration of these added elements from the desired value in the axial direction are suppressed.

The silicon single crystal in the present invention also includes one doped with phosphorus, boron, or the like. In addition, in the method of the present invention, raw materials are replenished into the crucible according to the amount of single crystal pulled, and in order to control the concentration of sulfur, tin, or lead in the melt, these elemental components are replenished together with the polycrystalline silicon raw material. In some cases, there are cases in which there is no replenishment. When replenishing these elemental components, these elements or polycrystalline silicon to which these elements have been added in advance are replenished into the crucible. If these elements are not replenished, the amount of silicon raw material that is less than the amount of single crystal pulled is replenished, or the amount of silicon raw material that is equal to the amount of single crystal pulled is replenished.

This is because sulfur, tin, and lead all have relatively small segregation coefficients with respect to silicon, and in the case of sulfur and lead in particular, the segregation coefficients are extremely small at around 10-5. This is because the concentration of these elements in the melt can be maintained within a predetermined range even by replenishing only the silicon raw material into the crucible.

Hereinafter, the present invention will be explained in more detail based on embodiments.

When adding sulfur to the silicon wafer of the present invention, the desired concentration of sulfur C5,l is the optimum concentration required to improve the strength of the silicon wafer obtained from a single crystal. and 5×10”
~3X10"atoms/cm3, more preferably 5x1015~IX10"atOIIIS/c
It is within the range of m3. That is, the sulfur Me degree C in the wafer
If 5 is less than 5 x 10''atoms/cm3, the effect of suppressing the movement of dislocations when thermal stress is applied will not be sufficient, resulting in large warpage, and -3 x 10''atoms/cm3 This is because, even if added in excess of 1, the strength of the wafer will not be substantially improved any further, and sulfur will precipitate during crystal growth, making the crystal more likely to have dislocations.

Furthermore, when tin or lead is added to the silicon wafer of the present invention, the desired tin concentration C5n,i or the desired lead concentration CPb,i is determined by the desired strength of the silicon wafer obtained from a single crystal. This is the optimum concentration required to achieve a 5×10”
It is within the range of ~5×1079 atoms 7cm3.

In addition, a more preferable concentration for both tin and lead is I x 1016 to 5 x 1019 atoms/c
It is m3. That is, the tin concentration C5n or lead concentration Cl-5 in the wafer is 5×1°15 atoms/c.
If it is less than m3, the effect of suppressing the movement of dislocations when thermal stress is applied will not be sufficient, and the warpage will become large.
Even if more than cm3 is added, the strength of the wafer will not be substantially improved any further, and tin or lead will precipitate during crystal growth and the crystal will tend to have dislocations.

In the silicon single crystal used to obtain such a silicon wafer, the added sulfur concentration C5,
It is desirable that the tin concentration Csn or the lead concentration C2 does not vary as much as possible from the predetermined concentration in the axial direction, but if the variation is within ±20% of the predetermined concentration, the silicon single crystal This is acceptable because there is no substantial difference in the characteristics when the silicon wafers obtained from each site are processed in the same device process.

In the present invention, in order to produce a silicon single crystal in which sulfur, tin, or lead is intentionally added and whose concentration has little variation from the desired value in the axial direction,
The following method is used.

That is, when sulfur is added first, the sulfur concentration C5 in the melt at the part of the crucible where the silicon single crystal is pulled through the silicon single crystal pulling process. of,
5×1015 to 3×1016atoI in single crystal
±20% of the desired sulfur concentration C3,1 within the range of Ils/cm3 divided by the segregation coefficient kS of sulfur to silicon
The concentration is controlled to be within the following conditional expression (A): 0.8 (Cs, 1/kS)≦C5. ≦1.2
(Cs, +/kS)...(A) is controlled so that it holds true.

At the start of the single crystal pulling operation, the sulfur concentration Cs in the silicon melt at the single crystal pulling site. It is easy to maintain sulfur within the above range, and sulfur may be added together with the silicon raw material, or silicon to which sulfur has been added in advance may be added to a predetermined concentration depending on the amount of silicon melt.

However, the segregation coefficient kS of sulfur with respect to silicon is very small, about l Sulfur concentration in the melt at the site C3.

becomes concentrated over a considerable period of time, and soon falls outside the above range. Therefore, in the manufacturing method of the present invention,
Depending on the amount of single crystal pulled, an operation is performed to continuously or intermittently replenish the raw material to the portion of the crucible where the silicon single crystal is pulled, thereby increasing the sulfur concentration C5 in the melt.

is controlled within the range of the above conditional expression (A). In addition, as an operation for replenishing the raw material to the region in the crucible where the silicon single crystal is pulled, depending on the amount of single crystal pulled, several modes are considered as shown below. It will be done.

FIG. 1 is a diagram schematically showing the structure of an embodiment of the method for manufacturing a silicon single crystal of the present invention. In this embodiment, as shown in FIG. 1, a crucible 2 for forming a silicon melt 1 is composed of an inner crucible 2a having a through hole 3 at the bottom, and an outer crucible 2b surrounding the inner crucible 2a. It has a heavy structure. Further, the outer crucible 2b is supported by a support 4 connected to a driving means (not shown), so it can move up and down, and its relative position relative to the fixed inner crucible 2a can be varied. It is something that can be done.

In order to grow a single crystal according to the present invention using a pulling device having a crucible configured as described above, first, crucible 2 (
Sulfur or sulfur is added to both the inner crucible 2a and the outer crucible 2b) when filling the polycrystalline silicon raw material and impurities as a dopant as necessary to form the silicon melt 1, or immediately before pulling the silicon single crystal. The sulfur concentration in the melt 1a in the inner pot 2a is C3° and Sulfur concentration CS, s in the melt 1b outside the internal basin 2a. , or the following values.

Cs, , =Cs, , / kS C5,. p=cs Then, a pulling wire 5 is placed in the melt 1a in the internal basin 2a.
A seed crystal 6 fixed to the tip of the inner tank 2a is immersed in the seed crystal 6, and the seed crystal 6 is pulled up at a predetermined speed to grow a single crystal 7 at the tip of the seed crystal 6. At the same time, the melt 1affl in the internal tank 2a is Outer crucible 2b
Press -L. Therefore, sulfur ff is taken into the single crystal from the melt 1a in the internal pot 2a and decreases.
tffl and pushing up the outer crucible 2b-
The sulfur content in the melt flowing from the side to the inner pot 2a side through the through hole 3 is balanced, and the inside of the inner pot 2a (single crystal pulling part in the crucible 2) is maintained through the pulling operation of the single crystal 7.
The sulfur concentration C5 in the melt 1a. However, the conditional expression (A)
It satisfies the following.

However, when performing a single-crystal pulling operation using the crucible 2 having such a configuration, the sulfur concentration C3° in the melt 1a in the internal crucible 2a increases as described above through the single-crystal 7-pulling operation. If conditional expression (A) is satisfied, the internal pot 2a
The sulfur concentration Cs in the melt 1a within. and the sulfur concentration C5, l in the melt i(k l b) outside the internal pot 2a. Since it is concentrated as the crystal grows, the sulfur concentration C5 in the melt 1a at the start of pulling shall satisfy the above conditional expression (A),
The melt 1b does not contain sulfur, i.e. C3,5up
= 0, and the outside is adjusted so that the amount of melt 1b flowing into melt 1a through through hole 3 per unit time after the start of pulling is (1-kS) times the amount of single crystal pulled per unit time. If the crucible 2b is pushed up, the sulfur concentration CS in the melt 1a in the internal crucible 2a will increase through the single crystal 7-pulling operation.
, , is the conditional expression % expression % Furthermore, as a practical method with better operability, the following can be presented. That is, at the start of pulling, the sulfur concentration in the melt 1a is C5. The above conditional expression (A) is satisfied, the melt 1b is assumed to be free of sulfur, and the amount of the melt 1b flowing into the melt 1a through the through hole 3 after the start of pulling per unit time is, Push the outer crucible 2b by -1 so that the amount is the same as the amount of single crystal pulled per unit time.
- It is something that will continue to grow. This is because the segregation coefficient of sulfur is very small, about 1Xl0-5, and the amount of sulfur that is taken into the single crystal from the melt and reduced is extremely small. Even if only the polycrystalline silicon raw material (and an impurity as a dopant if necessary) is added so that the amount of melt 1a remains constant over time, and sulfur is not replenished, as long as it is within the normal pulling range, Sulfur concentration C5 in the melt 1a in the internal pot 2a through the pulling operation of the single crystal 7. This is because it does not deviate from the conditional expression (A).

Furthermore, the structure of the crucible is not limited to the shape shown in FIG. , and has a structure in which md can be replenished from the other site to the single crystal pulling site according to the amount of single crystal pulling, the desired single crystal can be produced by the above operations. It is something.

FIG. 2 is a diagram schematically showing the structure of another embodiment of the method for manufacturing a silicon single crystal according to the present invention. In this embodiment, as shown in FIG. 1, a raw material supply pipe 8 that can supply raw materials from the peripheral edge side of the crucible 2 in which the silicon melt 1 is formed is arranged.

In order to grow a single crystal according to the present invention using a pulling apparatus having such a configuration, first, a polycrystalline silicon raw material and, if necessary, an impurity as a dopant are loaded into a crucible 2 and a silicon melt 1 is grown. When forming or immediately before pulling a silicon single crystal, sulfur or silicon containing sulfur is added so that the sulfur concentration C5 in the melt 1 in the crucible 2 becomes the following value.

C3. -CS,/k.

On the other hand, a raw material supply hopper (
(not shown), in addition to the granular or powdered polycrystalline silicon raw material and optionally impurities as dopants, also granular or powdered sulfur or sulfur-bearing silicon is added to the sulfur concentration in this supplementary material. CS, b. ,
Load it so that it has the following values.

CS, sup =CS Then, the seed crystal 6 fixed to the tip of the pulling wire 5 is immersed into the melt 1 in the crucible 2, and the seed crystal 6 is immersed at a predetermined speed.
is pulled up to grow a single IW body 7 on the tip of the seed crystal 6. At the same time, depending on the pulling amount, the supplementary raw material prepared as described above is supplied from the raw material supply pipe 8 to the crucible 2. The melt 1 inside is continuously replenished. Therefore, crucible 2
The amount of sulfur that is taken into the single crystal from melt 1 in 7 Sulfur concentration CS in the melt 1 in the crucible 2 through the pulling operation.

The above conditional expression (A) is satisfied.

However, even when performing a pulling operation for a single crystal body using a pulling device with such a configuration, the single crystal body 7 puller 1-1- The sulfur concentration CS in the molten liquid 1 in the crucible 2 through the heating operation,
. Or, if the above conditional expression (A) is satisfied, crucible 2
The initial value of the sulfur concentration C8° in the melt 1 and the sulfur concentration C32 in the feedstock. The setting value of 2 does not necessarily need to be limited to the above values. Furthermore, in this embodiment, the replenishment raw material supplied from the raw material supply pipe 8 into the melt 1 is prepared in advance as having a predetermined concentration of sulfur, but the supply raw material as a polycrystalline silicon raw material or a dopant is It is also possible to have a configuration in which sulfur as a sulfur component raw material or silicon containing sulfur is not added to the impurities in advance, and these are supplied to the melt 1 from separate single heavy supply pipes 8. be. In this case, since it is possible to change the supply amount of the sulfur component raw material with respect to the supply amount of the polycrystalline silicon raw material at any time,
- Sulfur concentration CS, s in the feedstock fed to the melt 1 during the pouring operation. 2 can be easily changed, making it possible to more delicately adjust the sulfur concentration in the melt 1 according to the progress of the single crystal pulling operation.

In addition, if the feedstock does not contain sulfur, that is, CS,
*. , -0, by setting the single weight supply amount per unit time to (1-k,) times the single crystal pulling amount per unit time, the melt 1
The sulfur concentration C5o in the sample satisfies the conditional expression (A). Or, more practically, what is the amount of raw material replenishment per unit time? Even if the amount of sulfur is the same as that for a single crystal per hour, since the segregation coefficient of sulfur is very small as described above, the sulfur concentration C50 in the melt 1 is determined by the above conditional expression through the pulling operation of the single crystal 7 (A) will be satisfied.

In addition, when adding tin, it is necessary to
The tin concentration in the melt at the part where the silicon single crystal in the crucible is pulled through the pulling process is c5°. 5×1015 to 5×10”atoms/c in single crystal
Desired tin concentration C3° within the range of m3, where 1 is the segregation coefficient of tin with respect to silicon. The concentration is controlled within ±20% of the value divided by, that is, the following conditional expression (B) 0.8 (Cs., /kSo)≦C5n, o≦1.2
(Cso1/kSo)... (B) Control is performed so that the following holds true.

Furthermore, in the case of adding lead, the lead concentration Cpb in the melt at the portion in the crucible where the silicon single crystal is pulled through the silicon single crystal pulling process. 5×1015 to 5×10”atoms/
The desired lead concentration Cpb within the range of cm3 is controlled to within ±20% of the value obtained by dividing 1 by the segregation coefficient kPb of lead with respect to silicon, that is, the following conditional expression (C) 0.8 (Cp= , 1/kr-)≦Cpb≦1゜2
(Cp-, +/kp-)...(C) Control is performed so that the following holds true.

The specific single crystal pulling operation in the case of adding tin or lead to the silicon single crystal is the same as that exemplified above for the case of adding sulfur to the silicon single crystal. However, when adding tin, silicon is added to the melt in the region where the silicon single crystal is pulled in the crucible, as shown as one possible method when adding sulfur, which has an extremely small segregation coefficient with respect to silicon. The method of replenishing only the same amount of polycrystalline silicon raw material (and dopant) as the weight of the single-crystal product is as follows:
The segregation coefficient of tin with respect to silicon is 5o, which is 1.6X10-
2, the segregation coefficient of sulfur is considerably larger than 5, and there is a risk of deviating from the conditional expression (B) as the pulling progresses, so it is not suitable for embodiments where the pulled weight is large. I can not say.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

As a silicon wafer according to the present invention, a wafer to which a small amount of sulfur was added was first prepared and its characteristics were investigated.

First, in a drawing device having the configuration shown in FIG. 2, a predetermined amount of polycrystalline silicon raw material is melted in a crucible 2 to form a melt 1. Furthermore, 5. OX 10”'atoII+s/cm
An amount of sulfur corresponding to a concentration of 3 was added. Then, while pulling a single crystal with a diameter of 5 inches according to a conventional method, powdered polycrystalline silicon raw material in an amount equal to the pulling amount was continuously supplied into the crucible 2 from the raw material supply pipe 8. The growth was continued until the weight of the fish reached approximately 30 kg.

Regarding the silicon single crystal obtained in this way, when the sulfur concentration C5 of each part in the axial direction was analyzed by chemical analysis method, it was found that the sulfur concentration C5 in each part was about 5 × 1015
A single crystal having a uniform atoIIls/cm3 and containing sulfur uniformly in the axial direction was obtained.

Furthermore, the silicon single crystal thus obtained was sliced and surface polished to produce wafers (thickness: 600 μm).

Then dry this silicon wafer.

2 atmospheres at 800℃ for 1 hour (dry0
2 atmosphere at 1000℃ for 10 hours, then dry02
The wafer was inserted into a furnace maintained at 1000°C in an atmosphere at a speed of 90 cm/min, held for 20 minutes, and then taken out at a speed of 90 cm/min for heat treatment, and the magnitude of warpage of the wafer after this heat treatment was measured. . The amount of warpage in the wafer is
The average size of the 10 samples was as small as 13 μm, indicating that the strength of this sulfur-added wafer is excellent.

Next, a wafer to which a small amount of tin was added was fabricated as a silicon wafer according to the present invention, and its characteristics were similarly investigated.

First, in a drawing device having the configuration shown in FIG. 2, a predetermined amount of polycrystalline silicon raw material is melted in a crucible 2 to form a melt 1. Furthermore, mushroom tin was added in a concentration corresponding to 3.0XIO'°atoms/cm3 based on the amount of melt 1 in the crucible 2. Then, as in the case of adding sulfur as described above, while pulling up a single crystal with a diameter of 5 inches, the same amount of granular polycrystalline silicon raw material as the pulled amount is transferred from the raw material supply pipe 8 into the crucible 2. The growth was continued until the weight reached approximately 30 kg.

Regarding the silicon single crystal obtained in this way, the tin concentration C5n of each part in the axial direction was analyzed by atomic absorption spectroscopy, and it was found that the tin concentration C5n of each part in the axial direction was about 5 x l.
A single crystal with a uniform density of 0.018 atoms/cm3 and containing tin uniformly in the axial direction was obtained.

Further, the silicon single crystal thus obtained was sliced and the surface polished to produce Ueno (thickness: 600 μm).

This silicon wafer was then subjected to the same heat treatment as above, and the degree of warpage of the sea urchin/\ after this heat treatment was measured. The magnitude of warpage in the wafer was as small as 10 μm on average for 10 samples, indicating that the wafer to which tin was added had excellent strength.

Further, as a silicon wafer according to the present invention, a wafer 1 to which a small amount of lead was added was prepared, and its characteristics were similarly investigated.

First, in a pulling apparatus having the configuration shown in FIG. 2, a predetermined amount of polycrystalline silicon raw material is melted in a crucible 2 to form a melt 1. Furthermore, 1. Tooth lead corresponding to a concentration of OX 10"atoms/cm3 was added. After that, a single crystal with a diameter of 5 inches was pulled in the same manner as in the case of adding sulfur described above, but the pulling amount was The same amount of granular polycrystalline silicon (1 quintillion+1) was continuously fed into the crucible 2 from a single heavy feeder, and the growth was performed until the pulled weight was about 30 kg.

Regarding the silicon single crystal obtained in this way, when the lead concentration C1,6 at each part in the axial direction was analyzed by single f-absorption method, it was found that approximately I
A single crystal with a uniform density of 10 ''atoms/cm3 and a uniform whitening of lead in the axial direction was obtained.

Further, the silicon single crystal thus obtained was sliced and the surface polished to produce Ueno (thickness: 600 μm).

Then, this silicon wafer was subjected to heat treatment similar to that described above, and the magnitude of warpage of the wafer after this heat treatment was measured. The amount of warpage in the wafer was as small as 12 μm on average for 10 samples, indicating that this wafer containing lead had superior strength.

Furthermore, for comparison, a silicon wafer to which sulfur, tin, and lead were not added was fabricated and its properties were examined in the same manner.

First, in a pulling apparatus having the configuration shown in FIG. 2, a predetermined amount of polycrystalline silicon raw material is melted in a crucible 2 to form a melt 1. Then, while pulling a single crystal with a diameter of 5 inches using a conventional method, the same amount of granular polycrystalline silicon raw material as the pulled amount is continuously supplied into the crucible 2 from the raw material supply pipe 8, so that the pulled weight is reduced. The animals were raised until they weighed about 30 kg. Further, the silicon single crystal thus obtained was sliced and the surface polished to produce a wafer (thickness: 600 μm).

This silicon wafer was then subjected to heat treatment similar to that described above, and the degree of warpage of the wafer after this heat treatment was measured. The average size of warpage in the wafers was 22 μm for 10 samples, and the strength was significantly inferior to that of wafers to which sulfur, tin, or lead had been added.

. [Effects of the invention] As described above, the silicon wafer of the present invention has a size of 5×10
Sulfur in the range 15-3X101L'atoms/cm3, 5x1015-5x10]9atO1lIS/c
Tin within the range of m3, or 5 x 1015 to 5 x 1010
It is characterized by containing lead in the range of 19ato/cm3, exhibits excellent strength, and is less likely to warp due to thermal stress applied during the device process. For this reason, microfabrication is applied to the wafer surface.
It is expected that the product yield will be improved and the product quality will be improved without reducing the resolution of lithography.

Furthermore, in the method for manufacturing a silicon single crystal of the present invention,
In a method of pulling and growing a silicon single crystal from a silicon melt formed in a crucible, adding either sulfur, tin or lead to the melt together with the silicon raw material,
In the melt at the part where the silicon single crystal is pulled in the crucible, the gravel concentration is set to 5 × 10 in the single crystal.
Desired sulfur in the range of 15-3 x 101 batoms/cm3? l concentration as the segregation coefficient of gravel to silicon.
Set to a value within ±20% of the value divided by tkS, or set the tin or lead concentration to 5×1 in the single crystal.
The desired tin or tin concentration within the range of 0.5 to 5 x 1019 atoms/cm" is set to a value that is within ±20% of the segregation coefficient kSn of tin or lead to silicon or the value divided by b. Furthermore, depending on the single crystal pulling base, raw materials are continuously or intermittently supplied to the part of the crucible where the silicon single crystal is pulled, and through the single crystal pulling operation, the above-mentioned The method for producing a silicon single crystal is characterized in that the concentration of sulfur, tin, or tin in the melt at the part of the crucible from which the silicon single crystal is pulled is controlled within the predetermined range. The body has a concentration of sulfur, tin, or lead within the desired range, and the axial variation in the concentration of sulfur, tin, or lead is within ±20% of the predetermined concentration. Therefore, 6 produced from the silicon single crystal
All silicon wafers exhibit good strength, which reduces variation in quality and improves product yield.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an apparatus configuration used in an embodiment of the method for manufacturing a silicon single crystal of the present invention,
FIG. 2 is a diagram schematically showing an apparatus configuration used in another embodiment of the method for manufacturing a silicon single crystal of the present invention,
Figure 3 is a diagram showing the relationship between the sulfur concentration in a silicon wafer and the magnitude of warpage, Figure 4 is a diagram showing the relationship between the tin concentration in a silicon wafer and the magnitude of warpage, and Figure 5 is a diagram showing the relationship between the tin concentration in a silicon wafer and the magnitude of warpage. FIG. 3 is a diagram showing the relationship between tin concentration and warpage size. 1... Melt liquid, 1a... Melt liquid in the internal pot, 1b...
- Melt liquid outside the inner pot, 2... Crucible, 2a... Inner pot, 2b... Outer crucible, 3... Through hole, 4... Support body, 5... Pulling wire , 6... seed crystal, 7
... Single crystal, 8... Raw material supply pipe. Patent applicant Nippon Steel Corporation representative
Patent Attorney 8 1H Mikio (and 1 other person) Figure 3 509S amount (atoms/crn”)

Claims (2)

[Claims] (1) 5 x 10^1^5 to 3 x 10^1^6 atoms
Sulfur within the range /cm^3, 5x10^1^5 to 5x1
Tin within the range of 0^1^9 atoms/cm^3, or 5 x 10^1^5 to 5 x 10^1^9 atoms/cm
A silicon wafer characterized by containing lead within a range of ^3. (2) In a method of pulling and growing a silicon single crystal from a silicon melt formed in a crucible, one of sulfur, tin, or lead is added to the melt together with the silicon raw material, and the silicon single crystal in the crucible is grown. In the melt at the point where the crystal is pulled, the sulfur concentration is adjusted to 5× in the single crystal.
10^1^5~3 x 10^1^6 atoms/cm^3
Set the desired sulfur concentration within the range of ±20% of the value divided by the segregation coefficient k_S of sulfur to silicon, or set the concentration of tin or lead to a value within ±20% of the value obtained by dividing the desired sulfur concentration in the range of 5.
×10^1^5~5×10^1^9atoms/cm^
The desired tin or lead concentration within the range of 3 is determined by the segregation coefficient k_S_n or k_P of tin or lead with respect to silicon.
Set the value to be within ±20% of the value divided by _b, and further supply the raw material continuously or intermittently to the part of the crucible where the silicon single crystal is pulled, depending on the amount of single crystal pulled. and controlling the concentration of sulfur, tin or lead in the melt at the part of the crucible where the silicon single crystal is pulled within the predetermined range through the single crystal pulling operation. Production method.