JP2000100737A - Manufacture of epitaxial wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an epitaxial wafer having a low haze level by lowering the growth temp. in the epitaxial growth of an Si layer on the surface of an Si wafer in specific conditions by a specific temp. range from the normal growth temp. SOLUTION: An Si wafer having a crystal orientation <100> and an inclination angle of 0 deg.±1 deg. is carried into a reactor chamber (S1). Then the reactor chamber is held at a specified anneal temp. for a fixed time to anneal (S2), and then a silane type gas such as trichlorosilane, dichlorosilane or silane trichloride, etc., is poured into the reactor chamber, so that the silane type gas and H gas have specified partial pressures to make the epitaxial growth at a growth temp. held lower (S3) by about 50-100 deg.C than the normal growth temp. After these have ended, the reactor chamber temp. is lowered, and the epitaxial wafer having epitaxially grown is carried out (S4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an epitaxial wafer, and more particularly to a method for manufacturing an epitaxial wafer having a small haze level.

[0002]

2. Description of the Related Art Conventionally, there has been known an epitaxial wafer manufacturing method in which an epitaxial film of single crystal silicon is formed on the surface of a mirror-polished silicon wafer by an epitaxial growth method.

In recent years, as the degree of integration increases, in semiconductor devices having design rules of 0.18 μm or less, it is important to further improve the flatness of EP wafers and reduce particles of 0.1 μm or less. For this purpose, it is necessary to reduce the surface roughness of the epitaxial wafer surface generated during epitaxial growth. Further, it is necessary to lower the haze level so that particles of 0.1 μm or less on the surface of the epitaxial wafer can be detected. The haze is scattered light from the wafer surface, and is detected as a noise component of an optical particle counter. It also makes it difficult to detect fine particles of 0.1 μm or less. Therefore, it is necessary to lower the haze level of the epitaxial wafer in order to support highly integrated devices.

[0004] Many methods for manufacturing an epitaxial wafer have been proposed to reduce the haze level.
For example, as disclosed in Japanese Patent Application Laid-Open No. 9-63956, there is disclosed a technique for reducing the haze level by performing low-temperature growth under reduced pressure under growth conditions. According to the publication,
First, a mirror-finished silicon wafer is placed in a reaction chamber, and hydrogen gas (H
₂ ) is injected at a predetermined pressure. Then, the reaction chamber is kept at a predetermined annealing temperature (1000 ° C. or higher) for a fixed time to perform annealing (heat treatment). Thereafter, the hydrogen gas in the reaction chamber was evacuated, and a reaction gas composed of, for example, hydrogen gas and dichlorosilane (SiH ₂ CI ₂ ) was injected into the reaction chamber so that the pressure became about 13.3 kPa. At the growth temperature T (= 900 ° C)
By holding for a fixed time in the following, a single-crystal silicon thin film is epitaxially grown on the silicon wafer surface.

[0005]

However, the prior art disclosed in Japanese Patent Application Laid-Open No. 9-68956 has the following problems.

[0006] Generally, the epitaxial growth is carried out at a low pressure of about 13.3 kPa of the reaction gas.
(Hereinafter referred to as low pressure epitaxial growth) and 101.3 kP
There is a method of performing the process under the atmospheric pressure of about a (hereinafter referred to as atmospheric pressure epitaxial growth). Low-pressure epitaxial growth has the advantage of better control of the generated epitaxial film thickness and the specific resistance in the film than the atmospheric pressure epitaxial growth method. There is a disadvantage that the property is poor. Further, in the low pressure epitaxial growth, when the dopant is boron or phosphorus, the amount of auto-doping tends to increase. Furthermore, the low-pressure epitaxial growth method requires a vacuum in the reaction chamber, which requires additional equipment such as a vacuum pump, and has a disadvantage that the structure of the manufacturing apparatus is more complicated and expensive than atmospheric pressure epitaxial growth.

Therefore, the technology disclosed in the above publication is
As described above, the pressure is about 13.3 kPa (in the embodiment, 10.6 kPa).
kPa), there is a problem that the productivity of the epitaxial wafer is low. On the other hand, when manufacturing epitaxial wafers using the atmospheric pressure epitaxial growth method in order to increase the productivity of epitaxial wafers, there is naturally a need to lower the haze level. Technology is not enough.

Further, on the surface of the epitaxial wafer, fine particles generated in the apparatus, fine dust adhering during wafer handling, and crystal defects on the surface of the epitaxial wafer are detected by a particle counter. Among these particles, small particles (particle size of 100 nm
However, as semiconductor devices become finer in the future, this will have a significant effect on the reduction in device yield. In order to ensure that the number of minute particles is equal to or less than a predetermined value, the number must be measured. However, in an optical particle counter that is generally used, the optical signal reflected by particles having a particle size of 100 nm or less is minute, and is buried and hidden by the noise of the particle counter, that is, the optical signal due to the haze of the EP wafer. It has become difficult. Therefore, it becomes more difficult to accurately measure the number of particles as the haze level is higher. Therefore, the number of particles cannot be guaranteed, and it becomes difficult to guarantee the quality of the epitaxial wafer.

In addition, the atmospheric pressure epitaxial growth method comprises:
Although it is possible to perform epitaxial growth at a high speed, there is a problem that thermal stress is easily received and an epitaxial growth layer having good film quality cannot be obtained.

The present invention has been made in view of the above problems, and has as its object to provide a manufacturing method for manufacturing an epitaxial wafer having a low haze level under atmospheric pressure. Another object of the present invention is to obtain a highly reliable epitaxially grown layer having good film quality by reducing thermal stress.

[0011]

In order to achieve the above-mentioned object, a first method of the present invention is to provide a method in which a crystal orientation <100> and a tilt angle of 0 ° ± 1 ° are performed at a reaction gas pressure of an atmospheric pressure. In the method for manufacturing an epitaxial wafer, wherein a silicon layer is epitaxially grown on the surface of a silicon wafer, the growth temperature T is typically 50 ° C. higher than the normal growth temperature during the epitaxial growth.
About 100 ° C lower than that.

According to such a method, as a result of various experiments,
In a silicon wafer having a crystal orientation <100> and a tilt angle of 0 ° ± 1 °, when the growth temperature during epitaxial growth at atmospheric pressure is lowered by 50 ° C. or more and 100 ° C. lower than a normal growth temperature (for example, 950 in the case of SiHCl ₃ ). It has been found that the haze level has a minimum value when the temperature is set to not less than 1050 ° C.). As a result, the haze level is reduced, so that the S / S
N (accuracy) is improved, and the number of particles on the manufactured epitaxial wafer can be accurately measured.
Therefore, by using an epitaxial growth furnace used for growing an epitaxial wafer as a product, forming an epitaxial growth layer under such conditions, reducing the haze level, and accurately detecting the particles with a particle counter, the surface of the epitaxial wafer is obtained. And the process environment. Therefore, the particles measured by the epitaxial growth layer for evaluation lead to the evaluation of the cleanliness of the process environment and the evaluation of the epitaxial wafer manufactured by using this furnace. As a result, it is possible to guarantee the number of particles of the epitaxial wafer formed in the epitaxial growth furnace, improve the reliability of the quality of the manufactured epitaxial wafer, and obtain a high-quality epitaxial wafer. (In addition, As: arsenic, Sb: antimony-based doping gas whose auto-doping decreases at high temperature or under reduced pressure is difficult to obtain the effect.)

[0013]

[Table 1]

According to a second aspect of the present invention, in the method for manufacturing an epitaxial wafer according to the first aspect, annealing is performed at an annealing temperature of 950 ° C. or higher and lower than the melting point of silicon before the epitaxial growth.

According to this method, annealing before epitaxial growth is performed at an annealing temperature of 950 ° C. or higher and lower than the melting point of silicon. By performing the annealing at 950 ° C. or higher, a single crystal is formed without polycrystallizing the epitaxial film. Thereby, the productivity of the epitaxial wafer is improved. Further, since the annealing is performed at a temperature lower than the melting point of silicon, the epitaxial wafer does not melt.

According to a third aspect of the present invention, in the method for forming an epitaxial growth layer on the surface of a silicon wafer under atmospheric pressure, an annealing step of heating the silicon wafer at a first temperature for a predetermined time, and An epitaxial growth step of forming an epitaxial growth layer by introducing a source gas while maintaining the temperature at the second temperature, wherein the second temperature is lower than the first temperature.

According to such a method, even if epitaxial growth is performed at a low temperature, it is possible to obtain an epitaxial growth layer having good film quality by sufficiently increasing the annealing temperature. In addition, it is possible to reduce the haze level by performing epitaxial growth at a low temperature.

According to a fourth aspect of the present invention, in the epitaxial growth method according to the third aspect, the annealing step is performed in an epitaxial growth furnace. According to such a configuration, annealing and epitaxial growth can be extremely easily performed only by switching the gas.

According to a fifth aspect of the present invention, in the epitaxial growth method according to the fourth aspect, the annealing step is a step of heating the silicon wafer in a hydrogen gas atmosphere. In a sixth aspect of the present invention, in the epitaxial growth method according to claim 5, the epitaxial growth step is a step of forming an epitaxial growth layer by flowing a desired source gas into the epitaxial growth furnace at the same time as the end of the annealing step. It is characterized by the following.

According to this configuration, the high-temperature process can be minimized, annealing and growth can be continuously performed only by switching the gas, and the control of the film thickness is very good. It is easy to form a highly reliable epitaxial growth layer.

According to a seventh aspect of the present invention, in the epitaxial growth method according to the sixth aspect, the second temperature is the same as the first temperature.

According to this structure, since a change in temperature can be reduced, the silicon wafer is extremely unlikely to be subjected to thermal stress, and an epitaxial wafer having good film quality and high reliability can be obtained. . Eliminating the cooling time can also improve the productivity of the epitaxial wafer.

According to an eighth aspect of the present invention, in the epitaxial growth method according to the seventh aspect, the first and second temperatures are different from each other.
It is in the range of 950 ° C to 1050 ° C. Since annealing and epitaxial growth are performed in such a temperature range, the haze level can be reduced, and an epitaxially grown layer having good film quality can be obtained.

According to a ninth aspect of the present invention, in the epitaxial growth method according to the seventh aspect, the first and second temperatures are different from each other.
It is in the range of 950 ° C. to 1050 ° C., and in the epitaxial growth step, a mixed gas of trichlorosilane and hydrogen gas is supplied as a source gas.

According to a tenth aspect of the present invention, in the epitaxial growth method according to the seventh aspect, the first and second temperatures are different.
It is within a range of 900 ° C. to 1000 ° C., and a mixed gas of dichlorosilane and hydrogen gas is supplied as a source gas in the epitaxial growth step.

According to an eleventh aspect of the present invention, in the epitaxial growth method according to the seventh aspect, the first and second temperatures are different.
It is within a range of 850 ° C. to 940 ° C., and in the epitaxial growth step, a mixed gas of monosilane and hydrogen gas is supplied as a source gas.

In a twelfth aspect of the present invention, a step of loading a silicon wafer into an epitaxial growth furnace, and heating the silicon wafer to a constant temperature corresponding to an epitaxial growth temperature in the epitaxial growth furnace, and in a non-oxidizing atmosphere, An annealing step of heating for a time, and an epitaxial growth step of introducing a source gas at a predetermined flow rate while maintaining the epitaxial growth furnace at the constant temperature to form an epitaxial growth layer on the surface of the silicon wafer. It is characterized by.

According to this method, annealing and growth can be continuously performed only by switching the gas without raising or lowering the temperature of the epitaxial growth furnace.
A highly reliable epitaxial growth layer having a low haze level, good film quality and high reliability can be formed very easily. Also, since there is no waiting time from annealing to growth,
The heating time applied to the silicon wafer can be minimized, and epitaxial growth with high controllability and high productivity can be performed.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments according to the present invention will be described in detail.

FIG. 1 is an explanatory view showing a basic method for manufacturing an epitaxial wafer according to the present invention, in which the vertical axis shows the temperature in the reaction chamber and the horizontal axis shows the passage of time. In addition,
Here, each step number is represented by adding S. First, S1
Then, the silicon wafer whose surface is mirror-polished is carried into the reaction chamber. At this time, the inside of the reaction chamber is filled with hydrogen gas (annealing gas) at atmospheric pressure and kept at about 800 ° C. During this transfer, nitrogen (N ₂ ) gas, which is a filling gas in the front chamber, is mixed into the reaction chamber, so hydrogen gas is injected into the reaction chamber for a predetermined time, and the nitrogen gas is expelled to remove the hydrogen gas in the reaction chamber. Increase purity.

Next, in S2, the reaction chamber is kept at a predetermined annealing temperature for a fixed time to perform annealing. The annealing temperature at this time is 950 ° C. or higher and lower than the melting point of silicon. In the drawing, the range of the annealing temperature is indicated by oblique lines, and as an example, the annealing temperature is set to 1200 ° C., and this is indicated by a solid line.

[0032] Then, in S8, the reaction chamber, for example, trichlorosilane (SiHC1 ₃₎ or dichlorosilane (SiH ₂ CI _2), or injected with a silane-based gas such as tetrachloride silane (SICI _4),
The hydrogen gas and the silane-based gas are set to have a predetermined partial pressure. At this time, the same volume of hydrogen gas as the silane-based gas is discharged from the reaction chamber, and the pressure in the reaction chamber is kept at atmospheric pressure. Then, the reaction chamber is maintained at a predetermined growth temperature T for a fixed time to perform epitaxial growth.
At this time, the growth temperature T is kept at a constant temperature of 950 ° C. or more and 1050 ° C. or less. In the figure, the range of the growth temperature T is indicated by oblique lines, and as an example, the growth temperature T is set to 1000 ° C. and is indicated by a solid line.

Finally, when the epitaxial growth is completed in S4, the temperature of the reaction chamber is lowered, and the epitaxial wafer after the epitaxial growth is carried out. Thus, in the embodiment, the growth temperature T of the epitaxial wafer is set to 950 ° C. or more and 1050 ° C. or less. As a result, as described later, the haze level of the epitaxial wafer surface at atmospheric pressure is in a minimum range, so that a high quality epitaxial wafer having a flat surface can be obtained.

Next, a specific example in which the present applicant manufactures an epitaxial wafer based on the method for manufacturing an epitaxial wafer according to the present invention and measures the haze level thereof will be described.

As an example, test conditions when an epitaxial wafer is manufactured are as follows. · Furnace pressure: atmospheric pressure, annealing temperature: 12 0 0 ° C.-reactive gas: hydrogen gas and trichlorosilane (SiHC1 ₃₎ (partial pressure ratio 370: 1) Silicon wafer: crystal orientation <10 0>, the inclination angle of 0 ° ± 1 °

Under the above test conditions, the growth temperature T is set to T
1 (= 900 ° C), T2 (: 950 ° C), T8 (= 1000 ° C), T4 (= 1050 ° C), T
5 (= 1100 ° C.) and T6 (= 1130 ° C.) were changed in six ways. At this time, in the epitaxial wafer grown at the growth temperature T1 (= 900 ° C.), a part of the epitaxial film was polycrystallized, and a complete single crystal epitaxial film could not be grown. Therefore, for each of the growth temperatures T2-T6 excluding the growth temperature T1 (= 900 ° C), the thickness t of the epitaxial film is set to tl (= 1
1), t2 (= 2 microns), t3 (= 4 microns)
Five types of epitaxial wafers were manufactured.

FIG. 2 is a graph showing the relationship between the growth temperature T and the haze level in the epitaxial wafer having each thickness t. In the graph, the horizontal axis indicates the growth temperature T, and the vertical axis indicates the haze level. The haze level is evaluated based on the ratio of the intensity of light, which is irregularly reflected by the haze and enters a predetermined sensor, out of the laser light emitted from the particle counter to the epitaxial wafer. For measurement, a particle counter manufactured by KLA Tencor, SFS (surf scan) was used. As shown in the figure, even when the thickness t was changed, the haze level showed a minimum value when the growth temperature T was 950 ° C. or more and 1050 ° C. or less. That is, the haze of the epitaxial wafer is reduced by setting the growth temperature T during the epitaxial growth in the atmospheric pressure epitaxial to 950 ° C. or more and 1050 ° C. or less. Also, from the figure,
It can be seen that the haze level decreases as the thickness t increases.

FIG. 8 shows the results obtained by applying particles having a particle size of 87 μm to the surface of an epitaxial wafer having a thickness t3 (= 4 μm) and measuring the surface with a particle counter. Shown for each T. The axis is the particle size of the particles, and the vertical axis is the number of particles counted in the particle count. The particle counter used for the measurement is a particle counter SP1 manufactured by KLA Tencor. As shown in the figure, two peaks PI and P2 appear in the output of the particle counter in the epitaxial wafer at the growth temperature T3-T6. Particle size 8 7 on the surface of the epitaxial wafer
μm particles (standard size particles, material: PSL = Poly
Since Stylene Latex (request for spell reconfirmation) is applied, the peak P1 at a particle size of 87 μm is attributed to particles, and the peak P2 at other particle sizes is considered to be a haze. Thus, the particle counter
Haze is regarded as particles having a certain virtual particle diameter (hereinafter referred to as reduced particle diameter D), and the level is counted.

As described above, as a quality assurance requirement item for an epitaxial wafer, there is a demand to reduce the number of particles having a particle size of 100 μm or less to a predetermined value or less. The current particle counter can only measure particles up to a particle size of about 80 nm,
The number of particles of m or more and 100 nm or less is counted, and the number is guaranteed. However, the higher the converted particle diameter D, the more difficult it is to distinguish between the peak P1 due to true particles and the peak P2 due to haze, making it impossible to measure the number of particles having a small particle diameter.

As an example, the growth temperature T5 (= 11
The measurement result at the temperature of 2000 ° C.) is compared with the measurement result at the growth temperature T2 (950 ° C.). For example, the growth temperature T5 (; 11 0 0
(° C.), the converted particle diameter D is about 83 nm as shown in the graph, and it is no longer possible to discriminate between the peak P1 due to the applied particle having a particle diameter of 87 nm and the peak P2 due to the haze. Therefore, it is difficult to count the number of true particles having a particle size of less than 87 nm, and the particle size of the particles whose number can be guaranteed is not less than 87 nm and 100 nm.
It is as follows. Conversely, when the growth temperature T becomes lower, such as the growth temperature T2 (= 950 ° C.), the converted particle size D becomes as small as 80 nm, so that true particles having a particle size of 80 nm or more and 100 nm or less become smaller. Can be counted to guarantee the number of particles of an epitaxial wafer manufactured in the same epitaxial growth furnace. As described above, since particles having a smaller particle size can be measured as the growth temperature T is lowered, the measurement accuracy of the number of particles can be increased, and the reliability of the quality of the epitaxial wafer can be improved.

In particular, as apparent from FIG. 2, a silicon wafer having a crystal orientation <100> and a tilt angle of 0 ° ± 1 ° has a growth temperature of 950 at the time of epitaxial growth at atmospheric pressure.
It can be seen that the haze level takes a minimum value when the temperature is set to not less than 1050 ° C. As a result, the haze level can be reduced, so that the measurement accuracy (S / N ratio) of the particle counter is improved, and the number of particles on the manufactured epitaxial wafer can be accurately measured.

Therefore, using an epitaxial growth furnace used for growing an epitaxial wafer as a product,
Under such conditions, an epitaxial growth layer for evaluation is formed,
By reducing the haze level and accurately measuring only the particles with a particle counter, the contamination degree of the epitaxial growth furnace can be evaluated.

Therefore, the particles measured by the epitaxial growth layer for evaluation lead to the evaluation of the cleanliness of the epitaxial process and, consequently, the evaluation of the epitaxial wafer manufactured using this furnace. as a result,
It is possible to guarantee the number of particles of the epitaxial wafer formed in the epitaxial growth furnace, the reliability of the quality of the manufactured epitaxial wafer is improved,
A high quality epitaxial wafer can be obtained.

As described above, in order to grow a single-crystal epitaxial film of good quality with little haze in atmospheric pressure epitaxial growth, 1) the epitaxial film does not become polycrystalline. 2) The haze level is small. 3) The converted particle size D of the haze is low. It is necessary to satisfy the condition.

From the condition 1), the growth temperature T is 950 ° C. or more, from 2) the growth temperature T is 950 ° C. or more and 1050 ° C. or less, and from 3), the lower the growth temperature T, the better. By setting the growth temperature T to 950 ° C. or more and 1050 ° C. or less, it becomes possible to manufacture an epitaxial wafer of good quality with little haze.

As described above, according to this embodiment, the growth temperature T is set to 950 ° C. or more and 1050 in the atmospheric pressure epitaxial growth method.
By performing epitaxial growth at a temperature of
A high-quality wafer with a low haze level can be obtained. Further, this reduces the converted particle diameter D of the haze, so that the number of particles having a smaller particle diameter can be measured. Further, since the number of particles on the epitaxial wafer can be measured more accurately, the quality of the manufactured epitaxial wafer can be guaranteed with higher accuracy, and the reliability of the epitaxial wafer is improved.

Next, the growth of the epitaxial film when the annealing temperature is changed will be described. As an example, annealing was performed at annealing temperatures of 900 ° C., 950 ° C., and 1200 ° C. Then, epitaxial growth was performed on each wafer at a growth temperature T of 900 ° C. and 950 ° C. The results are shown in Table 2 below.

[0048]

[Table 2]

As shown in the table, the annealing temperature was 950 ° C.
And 1200 ° C., at an epitaxial temperature of 950 ° C.,
A single crystal epitaxial film could be grown.
However, the annealing temperature is 900 ° C and the growth temperature T is 900
° C and 950 ° C, and the annealing temperature is 950 ° C, 1200 ° C.
When the growth temperature T was 900 ° C. at 900 ° C., the epitaxial growth was hindered and the part of the epitaxial film was polycrystallized, and a single crystal epitaxial layer could not be formed. From these results, it is desirable that the annealing temperature during the annealing in the atmospheric pressure epitaxial growth be 950 ° C. or higher and lower than the melting point of silicon.

In the above embodiment, the annealing gas is hydrogen gas and the reaction gas during the epitaxial growth is trichlorosilane. However, the present invention is not limited to these types of gases, and the atmospheric pressure epitaxial growth is not limited. Is applicable.

The used crystal orientation <100>, inclination angle 0 °
The silicon wafer of the type of ± 1 ° has a characteristic that haze hardly occurs. According to the present invention, it has been found that in such a silicon wafer, the haze level takes a minimum value under a growth condition in a certain temperature range, and the temperature range is determined by paying attention to this. According to the method described above, the haze level can be reduced, which is particularly effective for this type of wafer.

Next, a second embodiment of the present invention will be described. FIG. 4 is a flow chart showing a process for manufacturing an epitaxial wafer according to the second embodiment of the present invention, in which the vertical axis shows the temperature in the reaction chamber and the horizontal axis shows the passage of time. Here, each step number is represented by adding S to it. First, in S1, a silicon wafer whose surface has been mirror-polished is carried into the reaction chamber. At this time, the inside of the reaction chamber is
(Annealing gas) and kept at about 800 ° C. During the transfer, nitrogen (N ₂ ) gas, which is a gas filled in the front chamber, is mixed into the reaction chamber. Therefore, hydrogen gas is injected (purged) into the reaction chamber only for a predetermined time, and the nitrogen gas is expelled to drive the reaction chamber. Increase the purity of hydrogen gas in the room.

Next, through a heating step Si for raising the furnace temperature to 1000 ° C. to the epitaxial growth temperature T, the reaction chamber is kept at this temperature (annealing temperature) for a fixed time in step S2 for annealing. The duration is 45-220 seconds. Then, in S3, trichlorosilane (Si
HC1 ₃₎ was injected, and the partial pressure of trichlorosilane 384Pa (= 2.8
A mixed gas atmosphere of hydrogen gas and trichlorosilane is formed so as to have a pressure of 9 Torr. At this time, the same volume of hydrogen gas as trichlorosilane is discharged from the reaction chamber, and the pressure in the reaction chamber is maintained at atmospheric pressure. In this way,
The reaction chamber is kept at the epitaxial growth temperature T for a fixed time to perform epitaxial growth.

Finally, when the epitaxial growth is completed in S4 through a temperature lowering step Sd, the temperature of the reaction chamber is lowered,
The epitaxial wafer after the epitaxial growth is carried out. The epitaxial wafer thus formed can be very easily annealed and epitaxially grown only by switching the gas.

In the epitaxial growth step, since the epitaxial growth layer is formed by flowing the raw material gas into the epitaxial growth furnace at the same time as the end of the annealing step, the production time is reduced by minimizing the waiting time and the high-temperature step. The performance is also improved. In addition, the process is such that annealing and growth can be continuously performed only by switching the gas, the controllability is excellent, the thickness control is extremely easy, the thermal stress is small, and a highly reliable epitaxial growth layer is formed. It becomes possible.

Further, since the wafer is maintained at the same temperature in both the annealing step and the epitaxial growth step, the temperature change is extremely small, the thermal stress can be reduced, and the epitaxial wafer having good film quality and high reliability can be obtained. Can be obtained.

Since annealing and epitaxial growth are performed at the above temperature, the haze level can be reduced, and an epitaxially grown layer having good film quality can be obtained.

In the above embodiment, the annealing and epitaxial growth temperatures were set at 1000 ° C.
When the temperature is lower than or equal to ° C., the haze level of the epitaxial wafer surface at atmospheric pressure is in a minimum range, so that it is possible to obtain a high quality epitaxial wafer having a flat surface.

Also, by changing the gas type, the optimum temperature also changes, and it has been confirmed that the conditions are in the following ranges.

[Brief description of the drawings]

FIG. 1 is an explanatory view illustrating a method for manufacturing an epitaxial wafer according to a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a growth temperature and a haze level.

FIG. 3 is a graph showing the relationship between the particle size and the number of counts at each growth temperature.

FIG. 4 is an explanatory view showing a method for manufacturing an epitaxial wafer according to a second embodiment of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeo Tamura 1324-2 Ogaharacho, Omura City, Nagasaki Prefecture Inside the Nagasaki Factory of Komatsu Electronic Metals Co., Ltd. Inside the corporation

Claims (12)

[Claims] 1. Atmospheric pressure, the crystal orientation is <100> or <11>
1> In a method for manufacturing an epitaxial wafer in which a silicon layer is epitaxially grown on the surface of a silicon wafer having a tilt angle of 0 ° ± 1 ° in the step <1>, the growth temperature T is generally 50 ° C. to 100 ° C. higher than a normal growth temperature during the epitaxial growth. A method for manufacturing an epitaxial wafer, characterized in that the temperature is reduced to a certain extent. 2. The method for manufacturing an epitaxial wafer according to claim 1, wherein the annealing is performed at an annealing temperature of 950 ° C. or higher and lower than the melting point of silicon before the epitaxial growth. 3. An annealing step of heating the silicon wafer at a first temperature for a certain time in a method for forming an epitaxial growth layer on a silicon wafer surface under atmospheric pressure;
An epitaxial growth step of maintaining the silicon wafer at a second temperature and introducing a source gas to form an epitaxial growth layer, wherein the second temperature is lower than the first temperature. 4. The method according to claim 1, wherein the annealing step is performed in an epitaxial growth furnace.
3. The epitaxial growth method according to 3. 5. The epitaxial growth method according to claim 4, wherein said annealing step is a step of heating the silicon wafer in a hydrogen gas atmosphere. 6. The epitaxial growth step is a step of forming an epitaxial growth layer by flowing a desired source gas into the epitaxial growth furnace simultaneously with the end of the annealing step.
The epitaxial growth method as described above. 7. The epitaxial growth method according to claim 6, wherein the second temperature is the same as the first temperature. 8. The method according to claim 1, wherein the first and second temperatures are between 950.degree.
The epitaxial growth method according to claim 7, wherein the temperature is within a range of 0 ° C. 9. The method according to claim 1, wherein the first and second temperatures are from 950 ° C. to 105
8. The method according to claim 7, wherein the temperature is within a range of 0 ° C., and a mixed gas of trichlorosilane and hydrogen gas is supplied as a source gas in the epitaxial growth step.
The epitaxial growth method as described above. 10. The method according to claim 1, wherein the first and second temperatures are from 900 ° C.
8. The epitaxial growth method according to claim 7, wherein the temperature is in a range of 1000 [deg.] C., and a mixed gas of dichlorosilane and hydrogen gas is supplied as a source gas in the epitaxial growth step. 11. The first and second temperatures are between 850 ° C.
8. A temperature range of 940 [deg.] C., and a mixed gas of monosilane gas and hydrogen gas is supplied as a source gas in the epitaxial growth step.
The epitaxial growth method as described above. 12. A step of carrying a silicon wafer into an epitaxial growth furnace, and an annealing step of heating the silicon wafer to a certain temperature corresponding to an epitaxial growth temperature in the epitaxial growth furnace and heating it in a non-oxidizing atmosphere for a certain time. And an epitaxial growth step of introducing a source gas at a predetermined flow ratio while maintaining the epitaxial growth furnace at the constant temperature to form an epitaxial growth layer on the surface of the silicon wafer. Wafer manufacturing method.