JP2003151987A - Semiconductor substrate and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power loss by having sufficient planarity and a high yield so as to have power of >=280 V and >=20 A by one element. SOLUTION: The contact structure of SiGe and Si is formed by laminating an Si layer 9-4 using a substrate obtained, by laminating an SiGe layer 9-2 on an Si substrate 9-1, based on Si and forming an Si layer 9-3 on it in advance. Since the SiGe layer is formed on the substrate to be used in advance, an SiGe process can be omitted and since the Si layer is formed on its surface, impurities can effectively be removed in a surface purifying process when forming Si on it and planarity can be suppressed. When a semiconductor device using the contact structure is formed, SiGe can finally be manufactured by a high yield.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate and a method for manufacturing a semiconductor substrate, and more particularly to SiGe / S.
The present invention relates to a semiconductor substrate and a method for manufacturing the semiconductor substrate, which increase the yield of transistors having an i-junction.

[0002]

2. Description of the Related Art A bipolar transistor using a SiGe film is capable of high-speed amplification operation of several tens GHz or more,
Widely used for high speed communication. We have
By utilizing such high speed in the power transistor, a low-loss power transistor with high-speed operation is realized.

FIG. 15 shows a known basic laminated structure of a heterojunction bipolar transistor (HBT). The SiGe film 101 is laminated on the upper surface of the Si substrate 102 to form the base of the transistor. SiGe
The film 101 has a Si layer 10 as a collector on one surface thereof.
3 in contact with the Si layer 10 and the Si layer 10 as an emitter on the other side
Touching 4. The collector electrode 105 is the Si substrate 10.
2, the emitter electrode 106 is formed in contact with the Si layer 104 as an emitter, and the base electrode 107 is formed in contact with the SiGe film 101.
Such a heterojunction bipolar transistor, which is a SiGe transistor, can be used as a base with low input impedance, and can be made faster than a Si transistor.

The SiGe film is a film in which Si and Ge are in a mixed crystal state, and the crystal structure thereof is similar to the diamond structure, and a Ge concentration of 50% or less is usually used. The SiGe film is processed after being formed as a film on the Si substrate. A chemical vapor deposition method is used as a technique for forming a SiGe film. FIG. 16 shows a known chemical vapor deposition apparatus for forming a SiGe film by using the chemical vapor deposition method. Si substrate 108 is vacuum container 1
09 and is mounted on the substrate table 110. Si
The substrate 108 is heated to a high temperature of 500 ° C. or higher while being placed on the substrate table 110. The silicon container gas (SiH ₄ , Si ₂
H ₆ ) and germanium compound gas (GeH ₄ ) are introduced. The silicon compound gas and the germanium compound gas filled in the vacuum container 109 undergo a thermochemical reaction at an appropriate pressure and an appropriate substrate temperature, and Si atoms and Ge atoms are deposited on the exposed surface of the Si substrate 108. SiGe on 108
It is formed by stacking SiGe films as a mixed crystal film.

Such film formation is performed according to the following procedure. The Si substrate 108 is transferred from the sample exchange chamber 111 to the substrate table 110. The temperature of the Si substrate 108 is 800
It is set to ~ 900 ° C. Si at such temperature
The heating time of the substrate 108 is about tens of minutes. By such heating, oxygen and carbon on the surface of the Si substrate 108 are removed. Such removal is carried out after cleaning the surface with S
The temperature for forming a film on the i-substrate 108 is set. The appropriate film forming temperature is usually 500 to 800 ° C. The mixed gas described above is introduced into the vacuum container 109 set to the film forming temperature. The film formation ends when the introduction of the mixed gas is stopped or the temperature drops. The film thickness of the formed SiGe film is adjusted by the film formation time and the gas supply pressure. G of SiGe film
The e concentration is adjusted by the mixing ratio of the mixed gas.

After the formation of the SiGe film 101, the SiGe
A Si layer 104 is further laminated on the film 101. The chemical vapor deposition apparatus having exactly the same structure as the chemical vapor deposition apparatus of FIG. 16 described above is also used for stacking Si layers. The chemical vapor deposition apparatus for forming such a Si layer is prepared separately from the chemical vapor deposition apparatus for forming the SiGe film 101, and the chemical vapor deposition apparatus for forming the SiGe film 101 is provided. It is rarely used in combination. In the SiGe / Si junction structure used for HBT, the conductivity type of SiGe and Si
Conductivity types are opposite to each other, and 10
A high concentration of ¹⁹ or more is often required. If the SiGe layer and the Si layer are deposited in the same deposition device for the dual purpose, the dopant at the time of Si doping remains in the device, and the residual dopant is mixed into the SiGe layer at the time of stacking the SiGe layer. Will end up. In order to avoid the occurrence of such an autodoping problem, the deposition apparatus for depositing the SiGe layer is usually used separately from the deposition apparatus for depositing the Si layer.

The substrate on which SiGe is already laminated is transferred to the sample stage 110 of another chemical vapor deposition apparatus. The temperature of the substrate is set to 800-900 ° C,
It is heated for several minutes to several tens of minutes. By this heating, impurities such as oxygen and carbon remaining on the substrate surface are removed. After this surface cleaning, the temperature of the substrate is set to the film forming temperature. The film forming temperature is usually set in the range of 500 to 800 ° C. Reaction container 109 in which the film forming temperature is set
Then, a silicon compound gas is introduced. The film formation of the Si film is started by introducing the reaction gas, and stopped by returning the substrate temperature to room temperature or by stopping the introduction of the reaction gas. The film thickness of the Si film is adjusted by the film formation time and the gas supply pressure.

In order to improve the performance and yield of the transistor, it is required that the SiGe film and the Si film to be formed be flat without any defects. The defects existing in the SiGe film and the Si film cause a leakage current in the transistor. Poor flatness causes deterioration of the accuracy of the processing process and deterioration of the yield. Such SiGe layer and Si
The known technique of forming a laminated structure of layers by a chemical vapor deposition method has problems in crystallinity and flatness. Two facts are known as causes of disorder in crystallinity and flatness. One of them is strain that occurs during film formation. The other one is stains existing on the initial surface of film formation after surface cleaning.

The strain of the film is caused by a slight difference in the lattice constant between the underlying SiGe and the Si laminated thereon. Since the lattice constant of the SiGe film increases as the Ge concentration increases, the lattice expands and contracts near the contact interface of the SiGe film / Si substrate contact structure. Such expansion and contraction is the cause of distortion. If strain occurs, crystal defects called dislocations occur in the SiGe film. Such crystal defects induce stacking faults, and the SiGe film in which stacking faults occur has multiple defects and loses flatness at the same time. In order to suppress such stacking fault induction, it is necessary to limit the Ge concentration difference between the two layers of the contact structure and the film thickness. As the Ge concentration difference condition and the film thickness condition for suppressing the generation of defects,
The result of the survey by Bean et al. Is Applied Physics Lett.
ers, 1989, 54, 925. Distortion of crystallinity and flatness due to the influence of strain can be avoided according to the conditions, but it is still difficult to suppress the occurrence of defects due to the influence of dirt. In particular, S
After stacking the iGe layer, once the SiGe is taken out from the chemical vapor deposition apparatus and then mounted in another chemical vapor deposition apparatus, SiGe
It is difficult to remove impurities adhering to the surface of the layer, and SiG
In the Si layer stacked on the upper surface of the e layer, it is difficult to suppress the occurrence of stacking faults due to impurities that cannot be completely removed.
It was difficult to secure the flatness of the i layer.

It is considered that impurities such as oxygen, carbon, fluorine, and metal atoms adhere to the surface as contaminants on the surface of the SiGe layer. To reduce impurities, conventionally, high-temperature heat treatment called surface cleaning is performed in a vacuum container after chemically cleaning the substrate surface before film formation. A technique using the RCA method is known as a typical example of the chemical cleaning, and is as follows. 1. Washing with ultrapure water for several minutes Immerse in a mixed solution of NH ₄ OH, H ₂ O ₂ and H ₂ O (ratio 1: 2: 7) at 2.75 ° C. for several minutes or more. 3. Washing with ultrapure water for several minutes 4. Immerse in 1% hydrofluoric acid at room temperature for a few minutes. 5. Washing with ultrapure water for several minutes 6. Immerse in a mixed solution of HCl, H ₂ O ₂ and H ₂ O (ratio 1: 2: 7) at room temperature for several minutes or longer. 7. Ultra pure water cleaning for several minutes 8. Immerse in 1% hydrofluoric acid at room temperature for a few minutes. 9. Washing with ultrapure water for several minutes 10. Immerse in a mixed solution of H ₂ SO ₄ , H ₂ O ₂ , and H ₂ O (ratio 1: 2: 7) at room temperature for several minutes or longer. 11. Ultra pure water cleaning for several minutes 12. Spin drying

By such chemical cleaning, impurities on the substrate surface before film formation, particularly carbon impurities, metal atoms and fine particles are removed. However, there remains a problem that the SiGe film is dissolved by the acid treatment, an etch pit is generated on the surface, and the flatness is lost. Si with lost surface flatness
An electronic device having a SiGe / Si junction formed by stacking Si on a Ge film has an extremely high probability of failure and is unsatisfactory. As a cleaning that does not rely on the above-mentioned chemical cleaning, cleaning using acetone is known. It is often practiced to skip such a cleaning step and move to the Si laminating step without cleaning. In such a process, the effect of removing impurities is small, it is difficult to effectively suppress the occurrence of stacking faults due to the presence of impurities, and the crystallinity of the Si film is poor and it is difficult to secure flatness. .

In addition to the problem caused by impurities, there is a problem caused by heating. SiG that has been chemically cleaned as described above
The stacked substrate of e is introduced into a chemical vapor deposition apparatus, and cleaning by heating is always performed before Si is stacked on the surface. This heating is set to 800 to 900 ° C., and this heating reduces carbon impurities and oxygen impurities remaining on the surface to below the detection limit. At this time, if heating is performed at this temperature, Ge atoms are volatilized from the laminated SiGe film, the Ge concentration of the SiGe layer is lowered, and there is a problem that the surface is uneven due to volatilization. Therefore, when a Si layer is stacked on top of this to form a SiGe / Si junction, there is a problem in that the stack itself has irregularities.

Due to such a phenomenon, two chemical vapor deposition devices are used to maintain high quality crystallinity and SiGe.
It is currently difficult to form a / Si junction. 1
In order to consistently form a SiGe / Si junction using a chemical vapor deposition apparatus on a table, the doping atoms during Si film formation must be S
In order to avoid the auto-doping that is mixed during the iGe film formation, there is a problem that the time taken for cleaning the reaction container becomes long and the through top of the apparatus is lowered.

In HBT, the SiGe / Si junction in which the SiGe layer and the Si layer are directly joined is formed as an indispensable structure. It is required to provide a SiGe / Si film laminated substrate in which the crystallinity and flatness of this junction structure are sufficient. It is important to establish a technique for manufacturing a SiGe / Si film laminated substrate having sufficient crystallinity and flatness. A film forming apparatus for forming a SiGe / Si film laminated substrate having sufficient crystallinity and flatness is required to be simple, have a high yield, and be practical.

[0015]

An object of the present invention is to provide a semiconductor substrate having sufficient flatness and a method for manufacturing the semiconductor substrate.

[0016]

Means for solving the problem Means for solving the problem are expressed as follows. The technical matters appearing in the expression are accompanied by parentheses (), and numbers, symbols and the like are added. The numbers, symbols and the like are technical matters constituting at least one embodiment or a plurality of examples of the plurality of embodiments or a plurality of examples of the present invention, particularly, the embodiment or the example. It corresponds to the reference numbers, reference symbols, etc. attached to the technical matters expressed in the drawings corresponding to. Such reference numbers and reference symbols clarify correspondences and bridges between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence / bridge does not mean that the technical matters described in the claims are limited to the technical matters of the embodiment or the examples.

In the semiconductor substrate according to the present invention, the SiGe layer (52) is laminated on the Si substrate (51) whose main component is Si, and the Si layer (53) is thinly formed on the upper surface thereof. The Si layer (53) on the upper surface of the SiGe layer (52) has a thickness of 50 Å or more. By providing a substrate having such a structure in advance, a new Si layer is stacked on the substrate in an appropriate amount, so that SiGe / S is formed on the semiconductor substrate.
It is possible to form a laminated structure of i. Si layer (53)
If the thickness is about 50 Å, this thickness is thin enough to be ignored as an electronic device, and by stacking a Si layer of any thickness on it, those who use it can freely decide Si / S with Si layer of different thickness
A laminated structure of i can be obtained. By using such a substrate, it is possible to avoid the occurrence of a problem related to the removal of impurities attached to the surface of the SiGe layer, which has been a problem in the past. In this case, the second
Surface cleaning is performed before stacking the Si layer, and the surface at this time is Si. Therefore, it is possible to apply the RCA method, which has been used in the past, to effectively perform surface cleaning. it can. By using a substrate with such a structure, it is possible to prevent deterioration, which has been a problem with the conventional cleaning of the surface of the SiGe layer, and to obtain a SiGe / Si laminated structure, there is only one film forming device. The benefits of this are obtained.

The method of manufacturing a semiconductor substrate according to the present invention comprises a first step of manufacturing the semiconductor substrate (6-1) in the vacuum container (1-1) and a step of manufacturing the semiconductor substrate (6-1) in the vacuum container (1). -1) and the second step of taking it out. The first step is to introduce the substrate (9-1) into the vacuum container (1-1), to form the SiGe layer (9-2) on the front surface side of the substrate (9-1), and S
forming a Si layer (9-3) on the iGe layer (9-2). The Si layer (9-3) has a certain thickness necessary to protect the SiGe layer (9-2) of the semiconductor substrate (6-1) taken out from the vacuum container (1-1) in the second step. And is formed sufficiently thin. It should be thin enough but not less than 50Å thick.

The method of manufacturing a semiconductor substrate according to the present invention comprises a first step of manufacturing the first substrate (13) in the first vacuum container (1-1) and a step of manufacturing the first substrate (13) in the first vacuum container. The second step of introducing into a second vacuum container (1-2) different from (1-1), and forming a layer on the first substrate (13) in the second vacuum container (1-2) to form a second layer. And the third step of forming the substrate (14). The use of a plurality of vacuum vessels is important in that a semiconductor substrate with a high yield can be manufactured.

The first step is the 1-1 step of introducing the first substrate (6) into the first vacuum container (1-1), and
The 1-2 step of forming the SiGe layer (9-2) on the surface side of the first substrate (6) and the first step of the SiGe layer (9-2).
The first to third steps of forming the Si layer (9-3). In the third step, the first Si layer (9-
3) Forming a second Si layer (9-4) on the surface side of 3)
It has one step. When the first substrate (13) is transferred from the first vacuum container (1-1) to the second vacuum container (1-2), the surface of the SiGe layer (9-2) is changed to the first Si layer (9-
3), the surface of the SiGe layer (9-2) is protected and the volatilization of Ge is suppressed during the chemical cleaning and physical cleaning described below. It has been proved by experiments that the thickness of the first Si layer (9-3) is important to be thicker than 50Å for such protection.

The first Si layer (9-3) of the first substrate (13)
It is particularly preferred that a fourth step of chemically cleaning is further added. The chemicals used for this chemical cleaning are
It does not attack the surface of the SiGe layer (9-2).

It is important to further comprise a fifth step of heating and cleaning the first substrate (13) in time preceding the step 3-1. The SiGe layer (9-
The volatilization of Ge on the surface of 2) is effectively suppressed by the first Si layer (9-3). The first substrate (1
It is important that the temperature of 3) is 800 ° C or higher. In the 1-2 step and the 1-3 step, the Si compound gas and the Ge compound gas are mixed in the first vacuum container (1-1).
Then, SiGe is formed into a film. It has been experimentally proved that it is important that the third substrate (6 or 9-1) is heated to 500 ° C. or higher in the steps 1-2 and 1-3. A sixth step of chemically cleaning the first substrate (13), and 3-1
It is important to further include a seventh step, which precedes the step in time by heating and cleaning the first substrate (13).

By the fourth step, the first Si layer (9-
The carbon atom density on the surface of 3) is 5 × 10 ¹² atom / cm ²
It is important that: By the fourth step, the oxygen atom density on the surface of the first Si layer (9-3) is 1 × 10 5.
It is preferably ¹⁵ atom / cm ² or less, but the oxygen atom density is not sufficiently low, and the fourth step is to immerse the first substrate (13) in an aqueous solution containing hydrofluoric acid.
-1 step, and 4-2 step of immersing the first substrate (13) in a mixed solution of sulfuric acid and hydrogen peroxide solution after the 4-1 step becomes important, and in particular, it is an impurity. Oxygen and carbon are removed. In this process, the first Si
The layer (9-3) effectively protects the SiGe layer (9-2). The addition of exposing the first Si layer (9-3) of the first substrate (13) to ozone is effective for enhancing the cleaning effect.

According to the fourth step, the first Si layer (9-
The carbon atom density on the surface of 3) is 5 × 10 ¹²atom / cm^TwoSince
Being suppressed below solves the problem of the present invention and is practical.
It is particularly important in that it can be effectively realized. This
The defect density of the semiconductor substrate (14) formed as
1000 / cm^TwoIt is suppressed below, and the section of the present invention
The problem is effectively resolved and achieved.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Corresponding to the drawings, an embodiment of a semiconductor substrate according to the present invention is that a SiGe / Si
A laminated structure is formed. As shown in FIG. 1, a SiGe layer (film) 5 is formed on a Si substrate 51 containing Si as a main component.
2 are stacked, and a Si layer (film) 53 is thinly formed on the upper surface side of the SiGe layer 52. The thickness of the Si layer 53 on the upper surface of the SiGe layer 52 is 50 Å or more. The substrate 50 having such a laminated structure formed of the Si substrate 51, the SiGe layer 52, and the Si layer 53 is provided to the general market as a substrate having a convenient shape or transferred to the transistor manufacturing room. By newly laminating an appropriate amount of Si layers on such a substrate 50, it is possible to form an SiGe / Si laminated structure that is appropriate as a transistor on a semiconductor substrate. If the thickness of the Si layer 53 is about 50 Å, this thickness is sufficiently thin that it can be ignored as an electronic device, and a person who uses this by stacking a Si layer of arbitrary thickness on it. Can freely obtain a SiGe / Si laminated structure having a Si layer having an arbitrary thickness.

FIG. 2 shows an embodiment of a method for manufacturing a semiconductor substrate or a manufacturing apparatus therefor according to the present invention. In this apparatus, a first film forming apparatus which is structurally the same as the above-described known film forming apparatus is provided together with a second film forming apparatus.
The first film forming apparatus 10-1 includes a first vacuum container 1-1. The inside of the first vacuum container 1-1 is adjusted to an appropriate degree of vacuum by the first vacuum pump 2-1. A first substrate mounting table 3-1 is arranged inside the first vacuum container 1-1. The first substrate mounting table 3-1 is heated by the first heater 4-1 so that the temperature can be adjusted. The first raw material gas 5-1 is introduced into the first vacuum container 1-1. Si substrate 6
-1 is a first opening / closing passage 8-1 from the first sample exchange chamber 7-1
1 is exchangeably introduced into the first vacuum container 1-1 and is placed on the first substrate platform 3-1.

The second film forming apparatus 10-2 is equipped with a second vacuum container 1-2, as shown in FIG. The inside of the second vacuum container 1-2 is adjusted to an appropriate degree of vacuum by the second vacuum pump 2-2. A second substrate mounting table 3-2 is arranged inside the second vacuum container 1-2. The second substrate mounting table 3-2 is heated by the second heater 4-2 so that its temperature can be adjusted. The second raw material gas 5-2 is introduced into the second vacuum container 1-2. The second Si substrate 6-2 is the second
The sample is exchangeably introduced from the sample exchange chamber 7-2 into the second vacuum container 1-2 through the second opening / closing passage 8-2 and placed on the second substrate platform 3-2.

FIG. 4 shows details of the embodiment of the semiconductor substrate according to the present invention. The semiconductor substrate 9 includes a first Si substrate 9-1 containing Si as a main component and a first Si substrate 9-.
SiGe layer 9-2 that is directly bonded to the surface side of Si.
Si is directly bonded to the surface of the Ge layer 9-2 to prevent impurities from adhering to the surface layer portion of the SiGe layer 9-2.
Coating Si layer 9-3 for covering the surface layer portion of the Ge layer 9-2
And the second directly bonded to the surface side of the coating Si layer 9-3.
It is a laminated structure formed of the Si layer 9-4.

The joining surface region where the SiGe layer 9-2 and the covering Si layer 9-3 are joined has excellent flatness and crystallinity to the extent that the problems of the present invention can be sufficiently solved. There is. The coating Si layer 9-3 is bonded to the second Si layer 9-4, and the second Si layer 9-4 and the coating Si layer 9-3 integrally form one Si layer. 9-3 and Si
Since it is bonded to the Ge layer 9-2, the second Si layer 9-4
And Si for coating Si layer 9-3 are integrally joined
The layer is joined to the SiGe layer 9-2 and the SiGe layer 9-2
-2 which is a surface layer portion on the side of the coating Si layer 9-3.
The crystal defect density of the joint surface of the e / Si joint is sufficiently small.

Example: As shown in FIG. 5, the Si substrate 6 has a diameter of 4 inches in the (100) plane orientation. Before being introduced into the first vacuum container 1-1, the Si substrate 6 has already been subjected to the chemical cleaning process of the procedure based on the above-mentioned RCA method described below. 1. Cleaning with ultrapure water for several minutes Immerse in a mixed solution of NH ₄ OH, H ₂ O ₂ and H ₂ O (ratio 1: 2: 7) at 2.75 ° C. for several minutes or more. 3. Washing with ultrapure water for several minutes 4. Immerse in 1% hydrofluoric acid at room temperature for a few minutes. 5. Washing with ultrapure water for several minutes 6. Immerse in a mixed solution of HCl, H ₂ O ₂ and H ₂ O (ratio 1: 2: 7) at room temperature for several minutes or longer. 7. Ultra pure water cleaning for several minutes 8. Immerse in 1% hydrofluoric acid at room temperature for a few minutes. 9. Washing with ultrapure water for several minutes 10. Immerse in a mixed solution of H ₂ SO ₄ , H ₂ O ₂ , and H ₂ O (ratio 1: 2: 7) at room temperature for several minutes or longer. 11. Ultra pure water cleaning for several minutes 12. Spin drying

Si substrate 6 that has been subjected to such chemical cleaning
(Corresponding to the first Si substrate 9-1) is mounted on the first substrate mounting table 3-1 as shown in FIG.
-1 is introduced. Then, the air inside the first vacuum chamber 1-1, the pressure is 1 × ^{10 -} until 9 Torr,
It is exhausted by the first vacuum pump 2-1. Next, as shown in FIG. 7, the Si substrate 6 is heated at 800 to 900 ° C. for 5 minutes to clean the surface of the Si substrate 6. Oxygen and carbon are removed by this surface cleaning treatment.

Next, the temperature of the first Si substrate 9-1 is 700.
Set to ° C. The temperature of the first Si substrate 9-1 is 700
As shown in FIG. 8, a mixed gas of Si ₂ H ₆ and GeH ₄ is introduced as a raw material raw material gas 5-1 into the inside of the first vacuum container 1-1 set to ° C. The introduction pressure of GeH ₄ is 4 × 10 ⁻⁵ Torr. The inside of the first vacuum container 1-1 is left as it is for 10 minutes. Next, the supply of GeH ₄ is stopped, after the supply of GeH ₄ is stopped for 10 seconds, the supply of _Si 2 _{H 6} 1Si
The heating of the substrates including the substrate 9-1 is stopped, and the film formation is stopped. By raising the film forming temperature in this step to higher than 500 ° C., the silicon compound gas can be effectively decomposed and the crystallinity of the SiGe layer deposited on the surface of the substrate 6 (9-1) can be maintained. it can.

The stack of Ge and the stack of Si are represented by the following formula. GeH ₄ adsorption: GeH ₄ (gas) + 4Si → 2Ge (adsorbed) + 4H
(Adsorbed) Si ₂ H ₆ adsorption: Si ₂ H ₆ (gas) + 2Si → 2Si- (adsorbed) +
6H (adsorbed) Hdesorption: 2H (adsorbed) → H ₂ (gas)

By the film formation in this series of steps, as shown in FIG. 8, the SiGe layer 9 is formed on the surface of the first Si substrate 9-1.
-2 is laminated and formed, and further, a coating Si layer 9-3 is laminated and formed on the surface of the SiGe layer 9-2. S
The film thickness of the iGe layer 9-2 is 2000Å
The thickness of the layer 9-3 is 50Å.

Next, the SiGe layer 9-2 and the covering Si layer 9 are formed.
As shown in FIG. 9, the first laminated substrate 13 in which -3 and -3 are laminated is taken out from the first vacuum container 1-1.
By this removal, the first laminated substrate 13 comes into contact with the atmosphere, but the surface of the SiGe layer 9-2 is protected by the coating Si layer 9-3, and impurities such as oxygen and carbon are contained in the SiGe layer. Adhesion to the surface of 9-2 is effectively avoided.

Next, the surface of the first laminated substrate 13 is chemically cleaned. The first laminated substrate 13 is
It is immersed in an aqueous solution in which 47% by mass of hydrofluoric acid is diluted to 1/50, and then immersed in a liquid in which sulfuric acid and hydrogen peroxide solution are mixed at a volume ratio of 1: 2. Hydrofluoric acid removes oxides on the surface of the first laminated substrate 13, which is the substrate surface at this stage. Sulfuric acid and hydrogen peroxide are the first
The density of carbon and metal element impurities existing on the surface of the laminated substrate 13 is effectively reduced. The surface of the SiGe layer 9-2 in such a chemical cleaning step is covered and protected by the coating Si layer 9-3, and it is effectively avoided that the flatness is lost by the acid-based solution. .

The carbon atom density on the surface of the coating Si layer 9-3 subjected to such chemical cleaning was observed by X-ray photoelectron spectroscopy, and the carbon atom density was 5 × 10 ¹² atom / cm ² or less. The oxygen atom density is suppressed to about 1 × 10 ¹⁵ atom / cm ² . The metal atom density is below the observation limit and is below 1 × 10 ¹¹ atom / cm ² . The impurity density of carbon and metal atoms is a sufficiently low residual density for the surface before the next Si stack. The oxygen atom density is Si
The amount is small enough to be removed by the heat treatment before film formation. By such a chemical cleaning treatment, it is found that the surface of the first laminated substrate 13 has no unevenness that can be observed with a microscope and the effective flatness is maintained.

It is effective to expose the first laminated substrate 13 to ozone instead of the above-mentioned chemical cleaning. Exciting air with a mercury lamp to generate ozone,
By exposing the laminated substrate 13, the carbon atom density is increased to 5
It can be set to × 10 ¹² atom / cm ² or less. The oxygen atom density exists on the order of 10 ¹⁵ atom / cm ² , and oxygen atoms having such a density can be sufficiently removed by heat treatment.

Next, as shown in FIG. 10, the first laminated substrate 13 is the second vacuum container 1 of the second film forming apparatus 10-2.
-2 is introduced. The inside of the second vacuum container 1-2 is evacuated, and as shown in FIG.
Is heated and held at 800-900 ° C for 5 minutes. By this heat treatment, oxygen on the surface of the first laminated substrate 13 is removed. During this heating step, the SiGe layer 9
-2 is covered and protected by the coating Si layer 9-3, so that volatilization of Ge in the SiGe film 9-2 is effectively suppressed, and no Ge escape is observed. It is an experimental fact that the volatilization suppressing effect is effectively exhibited by setting the film thickness of the coating Si layer 9-3 to 50 Å or more.

The thickness of the coating Si layer 9-3 of about 50 Å is negligible from the viewpoint of electronic devices,
It is as if the coating Si layer 9-3 having such a thin thickness does not exist. The electrical characteristics of the SiGe / Si junction, for example, the rectifying characteristic and the VI characteristic of the pn junction are determined by the SiGe layer 9-2 and the second vacuum vessel 1 stacked in the first vacuum vessel 1-1.
-2 determines the physical properties of the laminated Si layers. Therefore,
The lack of flatness and the deterioration of crystallinity due to the chemical cleaning and the high temperature treatment are effectively avoided by the presence of the coating Si layer 9-3, and sufficient rectification characteristics and sufficient rectification characteristics are obtained for the SiGe / Si bonding according to the procedure of the present invention. VI characteristics are obtained.

Next, as shown in FIG. 12, SiH ₆
Is introduced into the second vacuum container 1-2 at 2.2 × 10 ⁻⁴ Torr, and the temperature of the first laminated substrate 13 is set to 700 ° C. In this step, the third Si layer 9 is formed on the surface of the coating Si layer 9-3 which is the surface of the first laminated substrate 13.
-6 is deposited and formed, and the second laminated substrate 14 is manufactured. The third Si layer 9-6 includes a coating Si layer 9-3, and the coating Si layer 9-3 and the coating Si layer 9-3.
The total film thickness of the Si layer newly laminated on the surface of 6000
It is Å. If the film forming temperature at this time is lower than 500 ° C., the film forming rate becomes 10 Å / min or less, and practically preferable production efficiency cannot be obtained. The second laminated substrate 14 thus manufactured corresponds to the semiconductor substrate 9 shown in FIG.

Next, as shown in FIG. 13, the second laminated substrate 14 is taken out of the second vacuum container 1-2.
The semiconductor substrate 9 which is the second laminated substrate 14 has a three-layer bonding structure of the Si substrate 9-1 and the 2000 Å SiGe layer 9-2 and the 6000 Å third Si layer 9-6, and has a conspicuous unevenness by a microscope. I can't find it. Defect density is 1 cm
^It is suppressed to 1000 or less per ² and high quality crystallinity and flatness are maintained.

Comparative Example 1: SiGe in the first vacuum container 1-1
A comparative substrate is produced in which the coating Si layer 9-3 is not laminated on the layer 9-2. First vacuum container 1-1 to second vacuum container 1
Before being transferred to -2, the substrate is immersed in a mixed solution of sulfuric acid and hydrogen peroxide for the same chemical cleaning as in the example. During the immersion, etch pits presumed to be acid-induced dissolution were observed on the surface of the SiGe layer 9-2. A Si layer (corresponding to the second Si layer 9-4) is laminated on such a substrate. On the surface of the stack, stacking faults thought to have nuclei of etch pits were generated, and the density of stacking faults was several hundred thousand per cm ² . The Ge concentration in the SiGe layer in the laminated substrate of the comparative example is reduced to about 4%, while that of the example according to the present invention is maintained at 5%. Was observed. One of the causes of the decrease is the aforementioned volatilization.

Comparative Example 2: A comparative substrate is manufactured in which the coating Si layer 9-3 of the example is thinner than 50Å. Two types of such comparative substrates were produced in which the coating Si layer 9-3 had a thickness of 30Å and 40Å. In the comparative substrate having such a thickness, etch pits were generated by the chemical cleaning.
The occurrence of such etch pits is presumed to be due to the loss of the Si layer in the chemical cleaning process. A Si layer (corresponding to the third Si layer 9-6) of 600 is applied to such a sample.
As a result of stacking with a thickness of 0 Å and observing the surface, several thousand stacking faults per cm ^{2 that} are presumed to have been the etch pits became nuclei, and the crystallinity of the Si layer was deteriorated. It was clear.

FIG. 14 shows a laminated structure of the SiGe transistor. n ^- Si on the surface side of the n ⁺ Si substrate 21
The layer 22 is formed. p on the surface side of the n ^- Si layer 22
-SiGe layer 23 is formed. p-SiGe layer 2
An n ⁺ Si layer 24 is formed on the surface side of No. 3. n ⁺ S
The i layer 24 is laterally divided by etching. An emitter electrode is formed on the surface of the n ⁺ Si layer element 25 that is divided and formed. A base electrode 26 is formed on the exposed surface of the p-SiGe layer 23 between the adjacent n ⁺ Si layer elements 25. The collector electrode is formed on the back surface side of the n ⁺ Si substrate 21.

[0046]

The semiconductor substrate and the method of manufacturing a semiconductor substrate according to the present invention can improve the yield of manufacturing semiconductor devices or electronic devices.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor substrate according to the present invention.

FIG. 2 is a sectional view showing a part of an embodiment of a semiconductor substrate manufacturing apparatus according to the present invention.

FIG. 3 is a sectional view showing another portion of the embodiment of the semiconductor substrate manufacturing apparatus according to the present invention.

FIG. 4 is a sectional view showing details of the embodiment of the semiconductor substrate according to the present invention.

FIG. 5 is a cross-sectional view showing the procedure of the embodiment of the method for manufacturing a semiconductor substrate according to the present invention. FIG. 5 is a cross-sectional view showing the next procedure of the procedure of FIG.

FIG. 6 is a cross-sectional view showing the next procedure of the procedure of FIG.

FIG. 7 is a cross-sectional view showing the next procedure of the procedure of FIG.

FIG. 8 is a cross-sectional view showing a procedure next to the procedure in FIG. 7.

9 is a cross-sectional view showing the next procedure of the procedure of FIG.

FIG. 10 is a cross-sectional view showing a procedure next to the procedure in FIG. 9.

FIG. 11 is a cross-sectional view showing a procedure next to the procedure in FIG. 10.

FIG. 12 is a cross-sectional view showing a procedure next to the procedure in FIG. 11.

FIG. 13 is a cross-sectional view showing a procedure next to the procedure in FIG. 12.

FIG. 14 is a sectional view showing an embodiment of a transistor using a semiconductor substrate according to the present invention.

FIG. 15 is a cross-sectional view showing a known transistor.

FIG. 16 is a cross-sectional view showing a known manufacturing apparatus for manufacturing a semiconductor.

[Explanation of symbols]

6 ... Si substrate 9-1 ... Si substrate 9-2 ... SiGe layer 9-3 ... First Si layer 9-4 ... second Si layer 9-5 ... Second area portion 9-6 ... Si layer 1-1 ... First vacuum container 1-2 ... second vacuum container 13 ... First substrate 14 ... Second substrate

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5F003 AP04 AP06 AZ07 BB04 BC08                       BF06 BM01 BP11 BP31 BP41                 5F043 AA02 BB22 DD02                 5F045 AA06 AB01 AB02 AC01 AD11                       AE11 AF03 BB02 CA02 DP04                       HA14

Claims (13)

[Claims] 1. A semiconductor substrate including a substrate containing Si as a main component, a SiGe layer formed on the upper surface side of the substrate, and a Si layer formed on the upper surface side of the SiGe layer. 2. The semiconductor substrate according to claim 1, wherein the Si layer has a thickness of 50 Å or more. 3. A first method for manufacturing a semiconductor substrate in a vacuum container.
And a second step of taking the semiconductor substrate out of the vacuum container, the first step introducing the substrate into the vacuum container, and forming a SiGe layer on the front surface side of the substrate. And a step of forming a Si layer on the SiGe layer, the Si layer having a certain degree necessary to protect the SiGe layer of the semiconductor substrate taken out from the vacuum container in the second step. A method of manufacturing a semiconductor substrate, which is thick and sufficiently thin, and has a thickness of 50 Å or more. 4. A first step of manufacturing a first substrate in a first vacuum container; a second step of introducing the first substrate into a second vacuum container different from the first vacuum container; A third step of forming a layer on the first substrate to form a second substrate in a vacuum container, the first step including introducing the first substrate into the first vacuum container; 1 step, and 1-2 for forming a SiGe layer on the surface side of the first substrate
A third step of forming a first Si layer on the SiGe layer, and a third step of forming a second Si layer on the front surface side of the first Si layer.
A method of manufacturing a semiconductor substrate, comprising one step. 5. The method of manufacturing a semiconductor substrate according to claim 3, wherein the film thickness of the first Si layer is 50 Å or more. 6. The method further comprises a fourth step of temporally subsequent to the first step and temporally ahead of the second step, the step of chemically cleaning the first Si layer of the first substrate. 4. A method for manufacturing a semiconductor substrate according to 4. 7. The method of manufacturing a semiconductor substrate according to claim 3, further comprising a fifth step of heating and cleaning the first substrate prior to the 3-1st step in time. 8. The method of manufacturing a semiconductor substrate according to claim 6, wherein the temperature of the first substrate in the fourth step is 800 ° C. or higher. 9. The method of manufacturing a semiconductor substrate according to claim 1, wherein in the step 1-2, Si compound gas and Ge compound gas are introduced into the first vacuum container. 10. The manufacturing of a semiconductor substrate according to claim 1, wherein a Si compound gas is introduced into the first vacuum container in the steps 1-3 and 3-1. Method. 11. The semiconductor substrate according to claim 9, wherein the first substrate is heated to 500 ° C. or higher in the 1-2 step, the 1-3 step and the 3-1 step. Production method. 12. The fourth step comprises immersing the first substrate in an aqueous solution containing hydrofluoric acid.
7. The method of manufacturing a semiconductor substrate according to claim 6, comprising 1 step and 4-2 step of immersing the first substrate in a mixed solution of sulfuric acid and hydrogen peroxide solution after the 4-1 step. 13. The method of manufacturing a semiconductor substrate according to claim 4, further comprising a sixth step of exposing the first Si layer of the first substrate to ozone.