JP2000281490A - Silicon semiconductor substrate and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a silicon semiconductor substrate by which defects of a region near the surface of a silicon wafer can be detoxicat ed and a high-quality denuded zone(DZ) can be formed by heat treatment in a relatively short time. SOLUTION: A silicon melt having >=1×1016 and <=1.5×1019 atoms/cm3 nitrogen content is used to grow a single crystal at a cooling rate of >=2 deg.C/min in a temperature region from the melt temperature to 800 deg.C during the growth of the crystal. A silicon wafer prepared from the resultant single crystal is heated up to >=800 deg.C temperature at >=1 deg.C/s heating rate and then kept at the end-point temperature for >=1 min. The resultant silicon wafer is subsequently heat-treated at >=1,000 and <=1,300 deg.C temperature for >=1 h to form a DZ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the quality of a silicon semiconductor substrate, and more particularly to a method for manufacturing a silicon semiconductor substrate in which a high-quality DZ is formed on a surface region of a silicon wafer by heat treatment.

[0002]

2. Description of the Related Art When manufacturing a semiconductor device using a silicon semiconductor substrate, it is known that a crystal defect in the substrate causes an operation failure of the device, and the manufacturing yield of the device changes depending on the density of the crystal defects in the substrate. ing. In recent years, attention has been paid to a defect called COP (Crystal Originated Particle) as a crystal defect that causes this device operation failure. This is because when a silicon semiconductor substrate is etched with a mixed solution of ammonia and hydrogen peroxide, pits are generated on the substrate surface due to lattice defects in the crystals, and the pits are measured by an inspection device that counts particles on the substrate surface. It is so called. The COP is a name indicating all the defects detected by such a measuring method, and is generally called Czochralski (CZ).
In a silicon single crystal grown by the CZ method or a CZ method to which a magnetic field is applied, the substance of this defect is considered to be an octahedral-like void in the crystal (hereinafter, referred to as a hole defect), and this is called the structural defect of the device. It is estimated to cause severe destruction. Several techniques have been proposed so far as a technique for reducing or eliminating COPs harmful to device fabrication.

As a technique for eliminating COP, it is known that the crystal growth rate during growing a single crystal is 0.8 mm / min or less (Japanese Patent Laid-Open No. 2-267195). This is because by reducing the amount of vacancy-type point defects (vacancy), which is an element that creates vacancy defects, at the crystal growth interface, and by slowing down the cooling rate of the single crystal,
This is to suppress the occurrence of supersaturated vacancy type point defects (vacancies) generated during cooling. However, this method has a problem that productivity is reduced due to a reduction in the growth rate, and another type of crystal defect such as a dislocation loop is generated from the COP.

As a technique for suppressing the generation of COP, control of the cooling behavior of a single crystal, in particular, when the single crystal
It is known that the control of the time for passing through the temperature range of 000 ° C. is effective (JP-A-8-12493, JP-A-8-91983, and JP-A-9-227289). Since these techniques do not significantly reduce the growth rate of the single crystal, there is no problem in terms of productivity.
The lower limit of the OP density reduction is about 10 ⁵ / cm ³ , and it is difficult to achieve a further reduction, for example, a density of 10 ⁴ / cm ³ or less.

In addition to the COP reduction technique at the time of growing a single crystal, there is also known a technique of reducing and eliminating COP on the substrate surface by performing a heat treatment after slicing and polishing a single crystal to form a substrate. . For example, JP-A-3-233
No. 936 proposes performing a heat treatment at 800 to 1250 ° C. for 10 hours or less. However,
When heat treatment is performed in an oxidizing atmosphere shown in the examples of this publication, there is a defect that vacancy defects are transferred to the substrate surface due to oxidative erosion of the substrate surface and pits on the substrate surface increase, and It is difficult to reduce the COP density within a range of 1 μm from the substrate surface to 10 ⁴ / cm ³ or less.

Further, when cooling the crystal during crystal growth,
The holding time of the single crystal during cooling in the temperature range of 0 ° C. to 1100 ° C. is set to less than 80 minutes, or when growing the crystal, growing a silicon single crystal having a nitrogen concentration of 1 × 10 ¹⁴ / cm ³ , There is known a technique in which a silicon wafer is heat treated at a temperature of 1000 ° C. or more for 1 hour or more after processing the silicon wafer (Japanese Patent Application Laid-Open No. 10-98047). This is a technique that makes it easier to eliminate defects during heat treatment by shifting the size distribution of COP generated during crystal production to a smaller size. However, the effect of this size reduction is more remarkable as the oxygen concentration is lower. Therefore, the gettering ability using the generation of oxygen precipitates inside the substrate usually obtained by increasing the oxygen concentration in the substrate is reduced. Grant and CO
It is difficult to achieve a balance with the reduction of P, and it has not been carried out at an oxygen concentration of 7 to 10 × 10 ¹⁷ / cm ³ commonly used in the Czochralski method.

[0007] The present inventors have found that a silicon semiconductor substrate for fabricating a semiconductor device can effectively reduce or eliminate vacancy defects which are a problem in device fabrication which cannot be completely removed by the conventional technique as described above. As a method of manufacturing a silicon semiconductor substrate with high productivity, a silicon semiconductor substrate obtained from a silicon single crystal grown by a CZ method using a silicon melt containing a specific concentration of nitrogen is heated at 1000 ° C. in a non-oxidizing atmosphere. A method of manufacturing a silicon single crystal substrate which is heat-treated at a temperature of 1300 ° C. or less for 1 hour or more was proposed (Japanese Patent Application No. 10-122284). As described above, in the nitrogen-doped crystal, the point defect concentration and the aggregation behavior of the point defects at the time of growing the crystal are changed, so that no vacancy defect is formed in the crystal, and the oxygen precipitate is formed as a grown-in defect at a high density. And can be utilized as a gettering site, and this grown-in defect
Z is easily eliminated when Z is created, and a high-quality DZ can be created.

However, if a normal heat treatment furnace is used, it must be inserted into the furnace at a temperature of about 800 ° C. and heated to an annealing temperature at about 10 ° C./min. Growth was inevitable.

Further, rapid thermal annealing (RTA, rapid th
Magic Denuded Zone (MDZ) technology is known as a technology for controlling the quality of DZ only by thermal annealing (Electrochmical Society Proceeding Volume 98-13).
p.135, R. Falster et al.). This is a technique for suppressing the apparent precipitation of nitrogen-free crystals by suppressing the concentration of point defects on the substrate surface using rapid temperature rise. In order to suppress oxygen precipitation by controlling point defects, complicated control is required for the heating method and the like, and the effect is only a temporary appearance, so there is no effect depending on the heat treatment process of the device There are cases.

[0010]

As described above, as a semiconductor substrate which can meet the required characteristics accompanying further miniaturization and high integration of semiconductor devices in recent years, crystal defects near the surface of a silicon substrate are eliminated. It is desired to supply a semiconductor substrate having high quality DZ at low cost.

Accordingly, the present invention solves the above-mentioned problems in the prior art, and makes a defect in a region near the surface of a silicon wafer harmless by a heat treatment for a relatively short time to form a silicon semiconductor substrate capable of forming a high quality DZ. It is an object of the present invention to provide a method for producing the same.

[0012]

As a result of repeated and extensive studies on experiments and theoretical considerations on the efficient elimination of crystal defects in the surface region of a silicon wafer, particularly a nitrogen-added silicon wafer, by heat treatment, the wafer, especially a nitrogen-added silicon wafer, was obtained. By performing RTA annealing as a pretreatment for the annealing process for producing the DZ of the wafer, the heat treatment time can be shortened, and defects at the time of temperature rise, which cannot be avoided using a normal heat treatment furnace, can be avoided. Eliminating the growth and promoting the disappearance of oxygen precipitates specific to the nitrogen-doped material by increasing the temperature to a high temperature at which the shape becomes unstable before the precipitates grow, thereby reducing defects in the surface region. The present inventors have obtained a new finding that the annihilation depth can be made deeper, and have completed the present invention.

That is, the present invention relates to (1) a silicon single crystal produced by the Czochralski method, wherein the temperature range from the melt temperature to 800 ° C. during crystal growth is 2 ° C./min or more. Manufacturing a silicon semiconductor substrate characterized in that a silicon wafer formed from the single crystal grown in the step (1) is heated to a temperature of 800 ° C. or more at a temperature of 1 ° C./sec or more, and then held at an attained temperature for 1 minute or more. Is the way.

The present invention also provides (2) a nitrogen content of 1 × 1
A silicon wafer made from a silicon single crystal grown by a Czochralski method using a silicon melt having a density of 0 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less is 800
After heating to a temperature of 1 ° C / sec or more to a temperature of 1 ° C or more,
A method for manufacturing a silicon semiconductor substrate, wherein the temperature is maintained for at least one minute at an attained temperature.

The present invention also provides (3) a nitrogen content of 1 × 1
Using a silicon melt of 0 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less, the melt temperature during crystal growth to 800 ° C.
A silicon wafer formed from a single crystal grown at a cooling rate of 2 ° C./min or more at a temperature range of 1 ° C./sec or more at a temperature of 1 ° C./sec or more, and then at a temperature of 1 ° C./sec or more.
This is a method for manufacturing a silicon semiconductor substrate, wherein the silicon semiconductor substrate is held for at least one minute.

The present invention also provides (4) the above (1) to (3)
And further heat-treating the silicon semiconductor substrate produced by the method described in 1) at a temperature of 1000 ° C. or more and 1300 ° C. or less for 1 hour or more.

The present invention further provides (5) a silicon single crystal produced by the Czochralski method, wherein the temperature range from the melt temperature to 800 ° C. during crystal growth is set at a cooling rate of 2 ° C./min or more. A silicon wafer formed from the grown single crystal is heated at a temperature of 1 ° C./sec or more to a temperature of 800 ° C. or more, and then continuously heated at 1000 ° C. without lowering the heat treatment temperature.
A method for manufacturing a silicon semiconductor substrate, comprising performing treatment at a temperature of not less than 1300 ° C. for not less than 1 hour.

The present invention also provides (6) a method wherein the nitrogen content is 1 × 1
A silicon wafer formed from a single crystal grown using a silicon melt of 0 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less at a temperature of 1 ° C./sec or more up to a temperature of 800 ° C. or more. A method for manufacturing a silicon semiconductor substrate, comprising: performing a heat treatment at a temperature of 1,000 ° C. or more and 1300 ° C. or less for one hour or more without lowering the heat treatment temperature after the temperature is increased.

The present invention further provides (7) a nitrogen content of 1 ×
10¹⁶atoms / cm^Three1.5 × 10 or more ¹⁹atoms / cm^Threebelow
Using silicon melt, melt temperature during crystal growth up to 800
Single temperature grown up to 2 ° C at a cooling rate of 2 ° C / min or more
A silicon wafer made from crystals is heated to a temperature of 800 ° C or higher.
After heating at a temperature of 1 ° C / sec or more to the temperature, heat treatment temperature
1000 ° C or more and 1300 ° C or less without lowering
Silicon treated at a temperature of at least 1 hour
This is a method for manufacturing a semiconductor substrate.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.

First, a first invention relates to a silicon single crystal produced by the Czochralski method, wherein a temperature range from a melt temperature to 800 ° C. during crystal growth is set at a cooling rate of 2 ° C./min or more. A method for manufacturing a silicon semiconductor substrate, comprising: raising a silicon wafer formed from a grown single crystal to a temperature of 800 ° C. or more at a temperature of 1 ° C./sec or more, and holding the temperature at an attained temperature for 1 minute or more. It is.

During the silicon single crystal pull-up growth, quenching the temperature range from the melting point to 800 ° C. at 2.0 ° C./min or more suppresses aggregation of point defects and reduces vacancy defects. Further, nucleation of oxygen precipitates in the temperature range is suppressed, that is, generation of oxygen precipitates stable at high temperatures is suppressed.

More preferably, the temperature range from the melt temperature to 800 ° C. during crystal growth is 2 ° C./min or more, and 800 ° C. to 4 ° C.
A silicon wafer formed from a single crystal grown in a temperature range of 00 ° C. at a cooling rate of 1.0 ° C./min or more is used. 8
Quenching the temperature range of 00 ° C. to 400 ° C. at a rate of 1.0 ° C./min or more prevents vacancy defects from being internally oxidized and changed into a stable oxide, and as a result,
Vacancy defects destabilize heat treatment. On the other hand, oxygen precipitates suppress the nucleation rate but increase the nucleus density and promote fineness and dispersion. Therefore, the above melting point temperature ~ 800
In combination with rapid cooling in a temperature region up to ° C., vacancy defects and oxygen precipitates are further miniaturized and destabilized in the surface layer region of the silicon substrate.

In addition, increasing the cooling effect during pulling and growing a single crystal silicon ingot usually increases the cooling capacity at the solidification interface, thereby increasing the crystal growth rate and improving the crystal productivity. It also has the effect of reducing costs.

In the first aspect of the present invention, by controlling the cooling rate during the growth in this manner, a silicon single crystal manufactured by miniaturizing and destabilizing crystal defects such as vacancy defects and oxygen precipitates. 80 for silicon wafers made from
0 ° C or higher, more preferably 1 ° C /
After the temperature is raised at a temperature of at least 10 seconds / second, more preferably at a temperature of at least 10 ° C./second, a heat treatment is performed at a temperature attained for at least 1 minute. That is, when a normal heat treatment furnace is used, the wafer must be inserted into the furnace at a temperature of about 800 ° C. and heated to an annealing temperature at about 10 ° C./min. Heat treatment (RTA) with a rapid heating rate
By doing so, the growth of crystal defects in this temperature rise process is suppressed, and the growth of precipitates during the temperature rise in a long-time heat treatment for DZ formation performed thereafter is suppressed. Thus, the present invention reduces crystal defects in as grown crystals by controlling the cooling rate in the crystal growing step,
By miniaturizing and making crystal defects unstable at high temperatures, it is easy to eliminate these defects by high-temperature heat treatment, and furthermore, by the pre-heat treatment by RTA, the growth of crystal defects in the temperature-raising process is suppressed, and high quality DZ Can be created.

The Czochralski (CZ) method used in the manufacture of the silicon semiconductor substrate according to the first invention is not limited to the usual CZ method, but also includes various conventionally known addition methods such as a magnetic field application CZ method. CZ with special requirements
Any of them can be used as long as the above-mentioned predetermined manufacturing conditions are satisfied. In this regard, the same applies to the manufacturing methods according to the second to seventh inventions described below.

Next, in the second invention, the nitrogen content is 1 × 10
A silicon wafer formed from a silicon single crystal grown by a Czochralski method using a silicon melt of ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less was heated to 800 ° C.
A method for manufacturing a silicon semiconductor substrate, characterized in that the temperature is raised at a temperature of 1 ° C./sec or more to the above temperature, and the temperature is maintained at the reached temperature for 1 minute or more.

In order to suppress the generation of minute pits on the wafer surface without causing defects such as a change in electrical characteristics of the silicon wafer and a stacking fault during device heat treatment, the nitrogen content in the silicon wafer must be reduced by 1%. 0.0 × 10 ¹³ at
It is necessary to be oms / cm ³ or more and 1.0 × 10 ¹⁶ atoms / cm ³ or less. The nitrogen content in the silicon wafer is 1.0 × 1
If it is less than 0 ¹³ atoms / cm ³ , generation of minute pits on the wafer surface cannot be suppressed, and if it exceeds 1.0 × 10 ¹⁶ atoms / cm ³ , electrical characteristics such as carrier lifetime and resistivity change, and stacking faults This is because a good silicon semiconductor substrate cannot be obtained even if DZ is formed due to occurrence of phenomena.
The segregation coefficient of nitrogen incorporated in the crystal after solidification is described in the literature.
W. Zulehner and D. Huber; Crystals 8 -Growth, Prop
erties, and Applications-, p.28 (Springer-Verlag,
New York, 1982) in a 7 × 10 ^-4 As shown,
Nitrogen is grown at 1.0 × 10 ¹³ atoms / cm ³ or more and 1.0 × 10 ¹⁶ at by growing crystals using the melt having the above-mentioned nitrogen concentration.
It is possible to manufacture a silicon wafer containing oms / cm ³ or less. The nitrogen content in the wafer was determined by SIMS (Second
ary Ion Mass Spectroscopy: secondary ion mass spectrometer). However, in the case of SIMS measurement, it is difficult to measure on the order of 10 ¹³ , and a low nitrogen concentration may not be quantified in some cases. In this crystal, the effect of nitrogen addition similarly occurs.

Nitrogen changes the concentration of point defects and the aggregation behavior of point defects during crystal growth, and does not form vacancy defects of about 0.1 μm or more typified by COP in the crystal.
Usually, the crystal temperature during crystal growth is 1150 ° C. to 1050 ° C.
Vacancy defects are formed at a relatively high temperature within a range of about the same level. When a predetermined amount of nitrogen is contained, nitrogen suppresses agglomeration of atomic vacancies, thereby reducing the vacancy defects. On the other hand, nitrogen is 1000
It promotes the nucleation of oxygen precipitates in a low temperature range of from about 400C to about 450C, and generates high-density, finely dispersed oxygen precipitates.

According to the second aspect of the present invention, a silicon wafer formed from a silicon single crystal manufactured by adding nitrogen in this manner is subjected to a temperature of 800 ° C. or more, more preferably 1000 ° C.
After the temperature is raised to a temperature of 1 ° C./sec or more, more preferably 10 ° C./sec or more, a heat treatment is performed in which the temperature is maintained at the reached temperature for 1 minute or more. It is considered that the oxygen precipitate generated in the nitrogen-added crystal is dissolved due to a decrease in the oxygen concentration during the heat treatment for forming DZ. In the DZ generation heat treatment, it takes several hours to reach the target temperature as described above, during which time the oxygen precipitate grows and becomes difficult to dissolve. In the second aspect of the present invention, by performing the pre-heat treatment at a steep heating rate as described above, the oxygen precipitate is not grown at an elevated temperature, and the temperature is raised to a temperature at which the oxygen precipitate becomes unstable. In addition, it facilitates dissolution, suppresses the growth of precipitates at the time of raising the temperature by a long-time heat treatment for DZ production performed thereafter, and enables to produce high-quality DZ. .

Next, according to the third invention, the nitrogen content is 1 × 1
Using a silicon melt of 0 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less, the melt temperature during crystal growth to 800 ° C.
A silicon wafer formed from a single crystal grown at a cooling rate of 2 ° C./min or more at a temperature range of 1 ° C./sec or more at a temperature of 1 ° C./sec or more, and then at a temperature of 1 ° C./sec or more.
This is a method for manufacturing a silicon semiconductor substrate, wherein the silicon semiconductor substrate is held for at least one minute.

That is, in the third invention, when growing a crystal by the Czochralski method, the grown crystal is formed by combining the cooling temperature control technique in the first invention with the nitrogen doping technique in the second invention. After performing better control of the precipitation defects in the above, by performing the pre-heat treatment with the steep heating rate as described above, by the subsequent heat treatment for DZ production, further quality of This makes it possible to create a good DZ. In the manufacturing method according to the third aspect of the present invention, the operation and effect of each condition and the preferable range thereof are as follows.
Each is almost the same as that described above.

Next, a fourth invention provides a method of manufacturing a semiconductor device according to the first to third inventions, comprising:
A method for manufacturing a silicon semiconductor substrate, further comprising performing heat treatment at a temperature of 1000 ° C. or more and 1300 ° C. or less for 1 hour or more.

Since the silicon semiconductor substrate formed by the manufacturing method according to the first to third aspects of the present invention has been subjected to the pre-heat treatment in which the heating rate is increased as described above, the silicon semiconductor substrate thereafter has a temperature of 1000 ° C. or more and 1300 ° C. When subjected to a DZ generation heat treatment at a temperature of not more than 1 ° C. for 1 hour or more, precipitates do not grow at the time of the temperature rise, and oxygen precipitates are easily dissolved. In this case, the elimination of crystal defects effectively progresses in the wafer surface region, and a high-quality and deeper DZ is formed.

It should be noted that the fine oxygen precipitates inside the substrate, unlike those existing near the substrate surface, are completely diffused even after the heat treatment at the above-mentioned high temperature for a long time without the oxygen being diffused outward and being eliminated. Remains without dissolving and disappearing at a high density, for example, 10 ⁸ / cm ³ or more, grows in the heat treatment in the device manufacturing process, and induces crystal defects effective for the IG action.

The heat treatment temperature according to the fourth invention is 1
The temperature is preferably from 000 ° C to 1300 ° C, more preferably from 1100 ° C to 1200 ° C. If the temperature is low, a large amount of time is required for out-diffusion of oxygen, and if the temperature is too high, the thermal equilibrium solid solubility in the crystal is increased and the out-diffusion of oxygen does not occur. At 1150 ° C. or higher, the higher the temperature becomes, the more the surface of the substrate becomes rough. Generally, when the heat treatment furnace is operated at a high temperature, unexpected contamination of the furnace body is likely to occur. Therefore, it is desirable that the heat treatment temperature can be lowered to reduce the risk. Therefore, it is desirable to perform the heat treatment at the lowest possible temperature in the indicated temperature range, taking into account the required depth of the DZ and the allowable time of the heat treatment time from an economic viewpoint.

The heat treatment atmosphere is preferably a non-oxidizing atmosphere in which the oxygen concentration on the wafer surface can be effectively reduced, and as a result, oxygen precipitates generated by the addition of nitrogen can be easily eliminated. As the non-oxidizing gas, an argon gas is desirable from the viewpoint of economy. Although the use of helium gas has the advantage of reducing the purity of the contained impurities, especially the amount of impurity oxygen in the gas, it is economical and difficult to handle the heat treatment furnace due to the large thermal conductivity of helium gas. There's a problem. Nitrogen gas is inappropriate because it forms nitride on the substrate surface. A reducing atmosphere such as hydrogen can be used because it has the same effect as argon gas, but it is not always suitable because of the difficulty of handling, especially the danger of explosion.

It should be further noted that it is necessary to reduce the amount of impurities mixed during the heat treatment as much as possible.
This is because oxygen in the furnace atmosphere, including when the sample is inserted into the furnace, greatly affects the integrity of the DZ and the surface roughness of the crystal surface. Regarding this point, Japanese Patent Application No. 9-297
As pointed out in No. 158. It also points out that by reducing impurities, it is possible to further improve the crystallinity of the surface layer, and to use this effect to smooth the COP pits present on the crystal surface before heat treatment. Is possible.

An atmosphere containing not less than 0.01 vol% and not more than 100 vol% of oxygen may be used as the atmosphere gas instead of the non-oxidizing atmosphere. In this case, the surface needs to be polished again. The merit of mixing oxygen is that the management of impurities such as moisture mixed during the heat treatment, which was pointed out in the previous section, can be relaxed. As a specific atmosphere, a gas in which oxygen is mixed in an inert gas atmosphere such as argon is used. Although the amount of oxygen to be mixed is desirably several%, it is also possible to use 100 vol% oxygen gas. The mixing amount is 0.01 vol
If it is less than%, it is necessary to strictly control the entry of impurities such as moisture into the atmospheric gas, and the merit of mixing oxygen is lost. On the wafer surface after the heat treatment, traces of crystal defects are generated on the wafer surface like pits of chemical etching due to an oxide film generated during the heat treatment, and thus the surface needs to be polished again. In order to completely remove defect marks, the surface needs to be polished by 0.5 μm or more. Also,
If the re-polishing amount is larger than 1.0 μm, the re-polishing amount becomes 0.1
It is difficult to make the thickness of the surface defect-free layer in which the density of crystal defects of μm or more is 10 ⁴ / cm ³ or less 1 μm or more.

Next, a fifth invention relates to a silicon single crystal produced by the Czochralski method, wherein the temperature range from the melt temperature to 800 ° C. during crystal growth is set at a cooling rate of 2 ° C./min or more. After raising the temperature of the silicon wafer formed from the single crystal grown in the above at a temperature of 1 ° C./sec or more to a temperature of 800 ° C. or more, the silicon wafer is continuously heated at 1000 ° C. without lowering the heat treatment temperature.
A method for manufacturing a silicon semiconductor substrate, comprising performing treatment at a temperature of not less than 1300 ° C. for not less than 1 hour.

In the sixth invention, the nitrogen content is 1 × 10
A silicon wafer formed from a single crystal grown using a silicon melt of ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less is heated at a temperature of 1 ° C./sec or more to a temperature of 800 ° C. or more. After heating, continue the heat treatment without lowering the temperature.
A method for manufacturing a silicon semiconductor substrate, comprising performing treatment at a temperature of 000 ° C. or more and 1300 ° C. or less for 1 hour or more.

Further, in the seventh invention, the nitrogen content is 1 ×
10¹⁶atoms / cm^Three1.5 × 10 or more ¹⁹atoms / cm^Threebelow
Using silicon melt, melt temperature during crystal growth up to 800
Single temperature grown up to 2 ° C at a cooling rate of 2 ° C / min or more
A silicon wafer made from crystals is heated to a temperature of 800 ° C or higher.
After heating at a temperature of 1 ° C / sec or more to the temperature, heat treatment temperature
1000 ° C or more and 1300 ° C or less without lowering
Silicon treated at a temperature of at least 1 hour
This is a method for manufacturing a semiconductor substrate.

According to the fifth to seventh aspects of the present invention, after the pre-heat treatment step for the silicon wafer in the manufacturing method according to the first to third aspects of the present invention is performed without cooling the wafer, the step is continued. Then, the same process as the high-temperature heat treatment for producing DZ in the manufacturing method of the fourth invention is continuously performed. Therefore, after the pre-heat treatment, the step of once cooling and then again raising the temperature to the temperature range of the pre-heat treatment is omitted, so that the processing time is further shortened and the energy consumption required for the processing is reduced.
Further, since the cooling and re-heating steps are omitted, problems such as generation and growth of crystal defects in these steps do not occur, and as a result, the same or better than the fourth invention is obtained. DZ can be created.

In the fifth to seventh manufacturing methods, the operation and effect relating to each condition and the preferable range thereof are substantially the same as those described above.

[0045]

The present invention will be described below with reference to examples of the present invention.
The present invention is not limited by the description of these examples.

First, the specification of a crystal commonly used in the following embodiments according to the present invention will be described.

Crystal A A crystal having a diameter of 150 mm and a boron-doped specific resistance of 10 Ωcm was prepared. The cooling rate at the time of pulling up the crystal was 3 ° C./min from the melting point to 800 ° C., and 2 ° C./min from 800 ° C. to 400 ° C.

Crystal B A crystal having a diameter of 150 mm and a boron-doped specific resistance of 100 Ωcm was prepared. The cooling rate at the time of pulling up the crystals was 2 ° C./min from the melting point to 800 ° C. and 1 ° C./min from 800 ° C. to 400 ° C.

Crystal C A crystal having a diameter of 150 mm and a boron-doped specific resistance of 10 Ωcm was prepared. The cooling rate at the time of pulling up the crystal was 1 ° C./min from the melting point to 800 ° C., and 1 ° C./min from 800 ° C. to 400 ° C.

Crystal D Silicon nitride was melted together with the raw materials to form a crystal. In addition,
Silicon nitride has a nitrogen concentration of 3 × 1 in the raw material silicon melt.
0 ¹⁷ atoms / cm ³ were added. Using this melt, a diameter of 150 mm and a boron-doped specific resistance of 1
A crystal of 0 Ωcm was formed. The cooling rate at the time of pulling up the crystal was 3 ° C./min from the melting point to 800 ° C., and 2 ° C./min from 800 ° C. to 400 ° C.

Crystal E Silicon nitride was melted together with the raw materials to form a crystal. In addition,
Silicon nitride has a nitrogen concentration of 1 × 1 in the raw material silicon melt.
0 ¹⁸ atoms / cm ³ were added. Using this melt, a diameter of 150 mm and a boron-doped specific resistance of 1
A crystal of 0 Ωcm was formed. The cooling rate at the time of pulling up the crystal was 1 ° C./min from the melting point to 800 ° C., and 1 ° C./min from 800 ° C. to 400 ° C.

Example 1 Each of the crystals A, B, C, D and E was heat-treated in a lamp heating furnace. Heat treatment from room temperature (20 ℃ ± 3 ℃) to 2
The temperature was raised to 1200 ° C. at 0 ° C./sec, kept at 1200 ° C. for 1 minute, and then cooled to room temperature. Before and after the heat treatment at this time, the COP density of 0.1 μm or more existing on the outermost surface of the wafer was evaluated by repeating the SCl cleaning. Also,
Furthermore, the COP density was evaluated after polishing the surface by 1 μm. Table 1 shows the obtained results.

[0053]

[Table 1]

As shown in Table 1, the effect of reducing the defects on the wafer surface was observed by performing the above heat treatment. However, there was not much improvement in the areas deeper from the surface.

Example 2 Each of the crystals A, B, C, D and E was heat-treated in a lamp heating furnace. Heat treatment from room temperature (20 ℃ ± 3 ℃) to 2
The temperature was raised to 1200 ° C. at 0 ° C./sec, kept at 1200 ° C. for 1 minute, and then cooled to room temperature. Thereafter, these wafers are inserted into a normal heat treatment furnace at 800 ° C., and 10 ° C. /
After raising the temperature in 1 minute and holding at 1150 ° C. for 8 hours, −10 ° C. /
The temperature was lowered in minutes and the substrate was taken out at 800 ° C. As a gas used for the heat treatment, a gas produced by a purifier at a use point using argon gas supplied by a cold evaporator was used. The impurity concentration in the gas was 5 ppm or less. This gas was used as an atmosphere throughout the heat treatment. At the time of inserting the substrate, purging was performed by a purge box provided in front of the furnace, and after confirming that the atmosphere in front of the furnace in which the sample was on standby was an argon atmosphere with impurities of 5 ppm or less, the furnace port was opened and the substrate was opened. Was inserted.

Thereafter, the COP density was evaluated in the same manner as in Example 1. Table 2 shows the obtained results.

[0057]

[Table 2]

As shown in Table 2, when the heat treatment of Example 2 was performed, the effect of reducing defects was observed even in a region deeper than the surface as compared with Example 1.

Example 3 Each of the crystals A, B, C, D and E was inserted into a normal heat treatment furnace, and after the insertion, the temperature was increased at 10 ° C./min to 1150 ° C.
, And the temperature was lowered at -10 ° C / min, and the substrate was taken out at 900 ° C. At 900 ° C., the speed at which the wafer is inserted is increased, and the temperature rise rate of the wafer to 800 ° C. is about 2 ° C. based on the estimated wafer temperature measured by a thermocouple near the board.
/ Sec. As a gas used for the heat treatment, a gas produced by a purifier at a use point using argon gas supplied by a cold evaporator was used. The impurity concentration in the gas was 5 ppm or less. This gas was used as an atmosphere throughout the heat treatment. At the time of inserting the substrate, purging was performed by a purge box provided in front of the furnace, and after confirming that the atmosphere in front of the furnace in which the sample was on standby was an argon atmosphere with impurities of 5 ppm or less, the furnace port was opened and the substrate was opened. Was inserted.

Thereafter, the COP density was evaluated in the same manner as in Example 1. Table 3 shows the obtained results.

[0061]

[Table 3]

As shown in Table 3, when the heat treatment of the third embodiment was performed, the effect of reducing defects was observed even in a region deeper than the surface as compared with the first embodiment. Equal or better defect reduction effects were observed.

[0063]

As described above, according to the manufacturing method of the present invention, the heat treatment time can be shortened, and the quality of DZ formed in the surface region of the obtained silicon semiconductor substrate can be improved. The depth of the DZ is also deeper.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // G05D 23/19 H01L 21/26 F (72) Inventor Hiroyuki Deai 3- Ida, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 35-1 Nippon Steel Corporation Technology Development Division (72) Inventor Akiyoshi Tachikawa 3-35-1 Ida, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 35-1 Nippon Steel Corporation Technology Development Division (72) Inventor Hideki Yokota Kanagawa (3) Inventor Hikaru Sakamoto 3-35-1 Ida, Nakahara-ku, Kawasaki City, Kanagawa Prefecture F term (reference) 4G077 AA02 AB01 BA04 CF00 EA01 EC10 EH07 FE11 GA01 HA12 5H323 AA40 CA06 EE05 KK05

Claims (7)

[Claims] 1. A silicon single crystal produced by the Czochralski method, wherein the temperature of the melt during crystal growth is from 800 to 800.
A silicon wafer prepared from a single crystal grown at a cooling rate of 2 ° C./min or more at a temperature range of up to 2 ° C. is heated to a temperature of 800 ° C. or more at a temperature of 1 ° C./sec or more, and then reaches a temperature of 1 ° C. A method for manufacturing a silicon semiconductor substrate, wherein the silicon semiconductor substrate is held for at least one minute. 2. Silicon prepared from a silicon single crystal grown by a Czochralski method using a silicon melt having a nitrogen content of 1 × 10 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less. Wafer is heated to 800 ° C or higher
A method for producing a silicon semiconductor substrate, comprising: raising a temperature at a temperature of not less than ° C./sec; 3. A temperature from a melt temperature during crystal growth to 800 ° C. using a silicon melt having a nitrogen content of 1 × 10 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less. 2 areas
The method is characterized in that a silicon wafer formed from a single crystal grown at a cooling rate of at least 1 ° C./min is heated at a temperature of at least 1 ° C./sec to a temperature of at least 800 ° C., and then held at the attained temperature for at least 1 minute. Of manufacturing a silicon semiconductor substrate. 4. The method according to claim 1, further comprising the step of:
A method for manufacturing a silicon semiconductor substrate, comprising performing heat treatment at a temperature of 0 ° C. or less for 1 hour or more. 5. A silicon single crystal produced by the Czochralski method, wherein the temperature of the melt during crystal growth is from 800 to 800.
A silicon wafer formed from a single crystal grown at a cooling rate of 2 ° C./min or more at a temperature range of up to 2 ° C. is heated to a temperature of 800 ° C. or more at a temperature of 1 ° C./sec or more, and then the heat treatment temperature is lowered. A method for producing a silicon semiconductor substrate, wherein the treatment is continued at a temperature of 1000 ° C. or more and 1300 ° C. or less for 1 hour or more without performing the treatment. 6. A silicon wafer formed from a single crystal grown using a silicon melt having a nitrogen content of 1 × 10 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less,
After heating to a temperature of 1 ° C / sec or more to a temperature of 1 ° C or more,
1000 ° C or higher without lowering the heat treatment temperature 13
A method for producing a silicon semiconductor substrate, comprising treating at a temperature of 00 ° C. or less for 1 hour or more. 7. A temperature from a melt temperature during crystal growth to 800 ° C. using a silicon melt having a nitrogen content of 1 × 10 ¹⁶ atoms / cm ³ or more and 1.5 × 10 ¹⁹ atoms / cm ³ or less. 2 areas
A silicon wafer formed from a single crystal grown at a cooling rate of not less than 1 ° C./min is heated to a temperature of not less than 800 ° C. at a temperature of not less than 1 ° C./sec. A method for producing a silicon semiconductor substrate, comprising treating at a temperature of 1300 ° C. or less for 1 hour or more.