JP2002241195A - Method for producing epitaxial multilayer film and epitaxial multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To epitaxially grow a high quality Si1-xGex layer and an Si layer in a method for producing an epitaxial multilayer film and the epitaxial multilayer film. SOLUTION: The method of producing the epitaxial multilayer film by epitaxially growing the Si1-xGex layer (SG) and the Si layer (SI) on an Si substrate (SUB) includes: an Si1-xGex layer depositing process for epitaxially growing the Si1-xGex layer (SG) by feeding a source gas for Si and a source gas for Ge onto the Si substrate; and an Si layer depositing process for epitaxially growing the Si layer by feeding the source gas for Si onto the Si1-xGex layer at a film depositing temperature higher than that for the Si1-xGex layer depositing process. The depositing process includes a process for raising the temperature to the high film depositing temperature, and the source gas for Si is continuously fed onto the Si1-xGex layer during the temperature raising process while maintaining such a state that supply of the source gas for Ge has been stopped after completion of the Si1-xGex layer depositing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for manufacturing an epitaxial multilayer film for epitaxially growing an e layer and a Si layer, and an epitaxial multilayer film.

[0002]

2. Description of the Related Art An epitaxial multilayer film composed of a SiGe (silicon germanium) layer and a Si (silicon) layer is formed on a wafer, such as after polishing of a Si substrate or after forming a buried diffusion layer, by a vapor phase growth method or the like. A single crystal SiGe thin film and a single crystal Si thin film are formed.
Etc. are used for heterostructures. For example, a conventional HBT is composed of GaAs (gallium arsenide) and AlGaAs.
(Aluminum gallium arsenide), but in recent years, since SiGe has a smaller band gap than Si, HBT using SiGe for a base region or the like (hereinafter, referred to as SiGe-HBT) has been manufactured. Have been. This SiGe-HBT is easily compatible with the Si process, which has a wealth of accumulated technology, can be mixed with a Si-LSI (one chip), has lower manufacturing costs than GaAs devices, and is more environmentally friendly than Si. A is difficult
There is an advantage that a large amount of s and the like need not be used.

In order to increase the speed of the Si-MOSFET, a buffer layer of a lattice-relaxed SiGe film is formed on a Si substrate, and a tensile strained SGe film is formed thereon.
A device that forms an i film and uses a strained Si film as a channel has been developed and studied. Since this MOSFET uses a strained Si film whose electron mobility is increased as compared with bulk Si, the speed can be increased. Note that this MOS
In the FET, since a SiGe film serving as a lattice relaxation layer is formed on a Si substrate, the Ge composition ratio is increased at a constant rate in the film thickness direction, and Ge is formed at an interface where a strained Si film is formed.
Lattice relaxation is performed by increasing the composition ratio. In addition, SiGe
Development and research of fabricating a light emitting element with a superlattice multilayer film of a film and a Si film and fabricating an optical sensor or a solar cell with a diode structure composed of a SiGe film and a Si film have been developed.

[0004]

The above-mentioned HBT and MOSF
SiGe films such as ET are manufactured using UHV-CVD (ultra-high vacuum chemical
Vapor phase growth), GS-MBE (gas source molecular beam epitaxy)
C), LP-CVD (Low pressure chemical vapor deposition), etc.
The film is formed by using an apparatus according to the method. However, Si
Since the film is formed at a high temperature with good film quality and a high growth rate,
i _1-xGe_xIt should be performed at a temperature relatively higher than the layer deposition temperature.
Is required, but Si_{1- x}Ge_xAfter deposition of the layer, the source gas
After stopping the supply of heat and raising the temperature to the film formation temperature of the Si layer,
When the Si layer is formed, the surface state deteriorates.
Si_1-xGe_xThe phenomenon that the Ge composition ratio of the layer decreases
there were.

The present invention has been made in view of the above-mentioned problems, and provides a method of manufacturing an epitaxial multilayer film and an epitaxial multilayer film capable of epitaxially growing a high-quality Si _1-x Ge _x layer and a Si layer. With the goal.

[0006]

Means for Solving the Problems The present inventors have developed Si _1-x
As a result of research on the technology of epitaxially growing Si on the Ge _x layer, the surface state of the Si layer is changed due to the presence of a large amount of O (oxygen) near the interface between the Si _1-x G _x layer and the Si layer. It turned out to be worse. Then, the oxygen, Ge Si _1-x Ge _x layer has been found to be those adhered combines with oxygen contained in trace amounts in the Si _1-x Ge _x layer on the atmosphere during elevated temperature . Therefore, the present invention has been obtained from the above findings, and has the following configuration to solve the above-described problems.

Namely, the production method of an epitaxial multilayer film of the present invention is a method for producing an epitaxial multilayer film is epitaxially grown Si _1-x Ge _x layer and the Si layer on the Si substrate, Si in the Si substrate Forming a Si _1-x Ge _x layer by epitaxially growing the Si _1-x Ge _x layer by supplying a source gas of Ge and a source gas of Ge;
i _1-x Ge _x with a high temperature film forming temperature than layer forming step wherein the Si
_1-x Ge by _x supplied Si source gas onto the layer and a Si layer formation step of epitaxially growing said Si layer, the Si layer formation step, heating step of raising the temperature to the deposition temperature of the hot Wherein the temperature raising step includes the step of heating the Si _1-x Ge _x
When the supply of Ge source gas is stopped at the end of the layer forming step, the Si source gas is kept
It is characterized by continuing to supply on the i _1-x Ge _x layer.

[0008] In the manufacturing method of the epitaxial multilayer film, in the temperature raising step, in a state of stopping the supply of the source gas of Ge in Si _1-x Ge _x layer forming step at the end, while performing the temperature increase also the Si since the source gas continue to supply the Si _1-x Ge _x layer, a state in which Si _1-x Ge _x layer surface is covered by a thin Si, suppresses sublimation of Ge,
Si _1-x Ge _x layer Ge that roughening the surface aggregate or the like on the surface can also be suppressed, the surface or interface of the final Si _1-x Ge _x layer and the Si layer in a process having a Atsushi Nobori process The condition can be improved.

In the method of manufacturing an epitaxial multilayer film according to the present invention, in the Si layer forming step, the flow rate of the Si source gas is gradually increased to a flow rate required at the high film forming temperature during the temperature raising step. Preferably, it is changed. That is, in this method for manufacturing an epitaxial multilayer film, the flow rate of the Si source gas is gradually changed to the flow rate required at the film formation temperature of the Si layer during the temperature raising step.
The film quality of the i-layer is improved and the film thickness is easily controlled.

In addition, the production of the epitaxial multilayer film of the present invention
The fabrication method is based on the Si_1-xGe_xIn the layer forming step,
Si_1-xGe_xWhen the Ge composition ratio x of the layer is 0.05 ≦ x ≦ 0.3
And Si_1-xGe_xThe thickness t of the layer is 0 <t ≦ 1 μm
It is preferable that That is, this epitaxial
In the method of manufacturing a multilayer film, Si_1-xGe_xIn the layer formation process
And Si_1-xGe_xWhen the Ge composition ratio x of the layer is 0.05 ≦ x ≦
0.3 and Si _1-xGe_xWhen the thickness t of the layer is 0 <t ≦
By setting the thickness to 1 μm, generation of defects can be suppressed.
You.

Further, in the method of manufacturing an epitaxial multilayer film according to the present invention, in the step of forming a Si _1-x Ge _x layer,
Either H ₄ or Ge ₂ H ₆ is used as a Ge source gas, and any of SiH ₄ , SiH ₂ Cl ₂ or Si ₂ H ₆ is used as a Si source gas, and the Si
Growing _1-x Ge _x layer in the Si layer formation step, S
A technique of growing a Si layer forming step by low-pressure CVD using iH ₄ , SiH ₂ Cl ₂ or Si ₂ H ₆ as a Si source gas is employed.

[0012] In the manufacturing method of the epitaxial multilayer film, in the Si _1-x Ge _x layer forming step, GeH ₄ or G
e ₂ H ₆ as a Ge source gas and Si
Since the reduced pressure CVD H _4, one of SiH ₂ Cl ₂ or Si ₂ H ₆ as a source gas of Si to grow the Si _1-x Ge _x layer, is excellent in mass productivity.

In the method for producing an epitaxial multilayer film according to the present invention, the Si _1-x Ge _x layer contains C,
A technique in which the composition ratio y is set to 0 <y ≦ 0.05 is employed.
That is, in this method for manufacturing an epitaxial multilayer film,
By containing C (carbon) in the Si _1-x Ge _x layer and setting the C composition ratio y to 0 <y ≦ 0.05, B (boron)
When impurities such as are doped, the impurities hardly diffuse and the impurity distribution hardly collapses.

Further, in the method for manufacturing an epitaxial multilayer film according to the present invention, in the Si _1-x Ge _x layer forming step,
Using any one of iH ₃ CH ₃ , SiH ₂ (CH ₃ ) ₂ , CH _{4 and} C ₂ H ₂ as a C source gas, the above S
Preferably, an i _1-x Ge _x layer is grown. That is, in this method for manufacturing an epitaxial multilayer film, Si _1-x Ge _x
In the layer forming step, SiH ₃ CH ₃ , SiH ₂ (CH ₃ )
_{Since the} Si _1-x Ge _x layer is grown by low pressure CVD using either ₂ , CH ₄ or C ₂ H ₂ as a C source gas, mass productivity is excellent.

The epitaxial multilayer film of the present invention has a
Si epitaxially grown on a plate _1-xGe_xLayer and Si
An epitaxial multilayer film having a layer according to the present invention,
Manufactured by the method for manufacturing an epitaxial multilayer film of
And features. In this epitaxial multilayer, Si
While the temperature is being raised to the layer deposition temperature, the Si source gas
To Si_1-xGe_xSurfaces and interfaces to keep supplying on the layer
Good quality Si with excellent condition_1-xGe_xLayer and Si layer
And a high quality epitaxial multilayer film is obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an epitaxial multilayer film and an embodiment of the epitaxial multilayer film according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the epitaxial multilayer film of the present embodiment has a Si _1-x Ge _x layer SG and a Si layer SI epitaxially grown on a Si substrate SUB. Also described below. In order to manufacture the epitaxial multilayer film according to the present embodiment, first, a normal SC1 cleaning is performed on a Si substrate SUB having a plane orientation (001) with a polished wafer, and then a natural oxide film is removed with dilute hydrofluoric acid. Perform pre-processing.

Next, the Si substrate SUB after the pretreatment is
Put in a low pressure CVD furnace, pressure 4.0 × 10 ³ Pa, 50
A hydrogen bake treatment is performed at 900 ° C. for one minute in a slm hydrogen flow atmosphere. This low pressure CVD furnace uses, for example, a single wafer type and a lamp heating type. Further, after the hydrogen bake treatment, the Si _1-x Ge _x layer SG is subsequently epitaxially grown.

The conditions for growing the Si _1-x Ge _x layer SG are as follows: SiH ₄ is converted to a Si source gas and GeH ₄ is converted to Ge in a hydrogen atmosphere.
, A film formation temperature of 900 ° C. or lower, a Ge composition ratio x of 0.05 ≦ x ≦ 0.3, and
The thickness t is set to 0 <t ≦ 1 μm.

Next, until the desired film thickness Si _1-x Ge _x layer SG
When the deposition of Ge is completed, GeH, which is a Ge source gas, is used.
Stop the supply of _4, the deposition temperature of the next Si layer SI, performing heating ie to a predetermined temperature higher than the deposition temperature of the Si _1-x Ge _x layer SG. At this time, Ge source gas GeH
₄ a state of stopping the supply of, it continues to be supplied to SiH ₄ as the source gas of Si on Si _1-x Ge _x layer SG while performing heating. At this time, a Si source gas SiH ₄
Is gradually increased to a necessary flow rate at a predetermined film forming temperature of the Si layer.

When the temperature of the substrate reaches the film forming temperature of the Si layer SI and the flow rate of the Si source gas SiH ₄ reaches the required flow rate, the Si layer SI is placed on the Si _1-x Ge _x layer SG. Epitaxial growth is performed for a predetermined thickness.

As described above, in the present embodiment, Si _1-x Ge _x
At the end of the film formation of the layer SG, the supply of the Ge source gas is stopped, and the source gas of Si is changed to Si while the temperature is raised.
Since continuously supplied onto _1-x Ge _x layer SG, a state in which Si _1-x Ge _x layer SG surface is covered by a thin Si, G
suppresses sublimation of e, Si _1-x Ge _x layer Ge that roughening the surface aggregate, etc. SG surface can also be suppressed, Si _1-x is also a process having a Atsushi Nobori process Ge _x layer SG
In addition, the surface and interface state of the Si layer SI can be improved.

The Si _1-x Ge _x layer S according to the present embodiment
In the epitaxial multilayer film having G, the higher the Ge composition ratio x of the Si _1-x G _x layer SG, the smaller the critical film thickness (the film thickness that generates dislocations and causes lattice relaxation).
Thickness of _1-x Ge _x layer SG, when the Ge composition ratio x is high,
Need to be thinner. That is, the Si _1-x Ge _x layer S
If the Ge composition ratio x of G exceeds 0.3, the thickness is close to the critical thickness and defects easily occur, or the defect exceeds the critical thickness and defects occur.
m or less.

[0024]

EXAMPLE An epitaxial multilayer film was actually manufactured based on the above embodiment. For comparison, a device in which the supply of all the source gases was stopped when the temperature was raised was also manufactured. With respect to the epitaxial multilayer film thus manufactured, SIM
The results evaluated by S (secondary ion mass spectrometry) are shown in FIGS. Note that the line Ge in FIG. 2 indicates the Ge concentration, and the line O indicates the oxygen concentration.

The multilayer film formed by stopping the supply of all the source gases at the time of temperature rise has a high haze level, and a high oxygen concentration is detected near the interface of the SiGe layer as shown in FIG. while being in the multilayer films of examples of the present invention, the haze level is good surface state is significantly reduced, as shown in FIG. 2 (b), Si 1- x
Also in the vicinity of the interface of the Ge _x layer SG was low oxygen concentration. When comparing the Ge concentration (Ge composition ratio) between the two, it is understood that the peak is higher in the embodiment of the present invention than in the case where the supply of all the source gases is stopped at the time of raising the temperature.

As another embodiment, as shown in FIG. 3, a first Si layer SI1 and a second Si layer SI2 are respectively formed by a _first Si _1-x Ge _x layer SG1 and a second Si _1-x Ge _x layer SG2.
A film was formed through the above steps. In this case, for comparison, a device in which the supply of all the source gas was stopped at the time of raising the temperature was also manufactured. That is, FIG.
(B), the deposition temperature of the 1Si layer SI1 is higher than the 1Si _1-x Ge _x layer SG1, also the 2Si layer S
I2 deposition temperature of the is set higher than the deposition temperature of the first 2Si _1-x Ge _x layer SG2, in the embodiment of the present invention, it is carried out each heating in a state of continuing to supply the source gas for Si .

The results of the SIMS evaluation of the epitaxial multilayer film thus manufactured are shown in FIG.
(B). Note that the line Ge in FIG.
Indicates the oxygen concentration. Also in this case, the multilayer film formed by stopping the supply of all the source gases at the time of raising the temperature has a high haze level, and as shown in FIG.
While a high oxygen concentration is detected near the interface of the e-layer, the haze level is greatly reduced in the multilayer film of the embodiment of the present invention, and as shown in FIG.
A first Si _{1- x} Ge _x layer SG1 and a second Si _1-x Ge _x layer SG
The oxygen concentration was also low near the interface of No. 2. In this case as well, it can be seen that the peak of the Ge concentration is higher in the embodiment of the present invention than in the case where the supply of all the source gases is stopped during the temperature rise.

The technical scope of the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention.

For example, in the above embodiment, Si _1-x Ge _x
GeH ₄ and SiH ₄ were used for epitaxial growth of the layer SG, but Ge ₂ H ₆ was used as a Ge source gas and SiH ₂ C
l ₂ and Si ₂ H ₆ may be used as a Si source gas. In addition, SiH is used for epitaxial growth of the Si layer SI.
_{Although 4} was used, SiH ₂ Cl ₂ or Si ₂ H ₆ may be used as the Si source gas.

In the above embodiment, a polished wafer having a plane orientation (001) was used as the Si substrate.
A polished wafer having a different plane orientation or a wafer in the middle of a process of manufacturing a pattern-formed or impurity-doped Si-LSI may be used. Further, in the above embodiment, the pretreatment including the SC1 cleaning, the removal of the natural oxide film with dilute hydrofluoric acid, and the hydrogen bake treatment at 900 ° C. for 1 minute was performed. However, other pretreatment methods and different hydrogen bake temperatures, Time may be used. In these cases, the same effects as in the above embodiment can be obtained.

In the above embodiment, the Ge composition ratio x is
Constant Si_1-xGe_xLayer, but the Ge composition ratio x gradually increased
Of graded composition changed stepwise or stepwise composition changed stepwise
i_{1- x}Ge_xYou may apply to what used the layer. Ma
In another embodiment, Si_1-xGe_xC (carbon) in layer
And the C composition ratio y was set to 0 <y ≦ 0.05.
It may be applied to a multilayer film. That is, for example, HB
Using a SiGeC layer as a base layer in T,
When forming a multilayer film, C is contained within the above composition ratio range.
In the case where impurities such as B are doped,
Impurities are less likely to diffuse and the impurity distribution is less likely to collapse.
There is a point. In this case, the Si containing C_1-xGe_xLayer of
The formation is SiH_ThreeCH_Three, SiH _Two(CH_Three)_Two, CH_FourOr
C_TwoH_TwoEither of the above as a source gas of C for reduced pressure CVD
By doing so, high mass productivity can be obtained.

[0032]

According to the present invention, the following effects can be obtained.
According to the method for manufacturing an epitaxial multilayer film and the epitaxial multilayer film of the present invention, the supply of Ge source gas is stopped at the end of the Si _1-x Ge _x layer forming step, and the Si Since the source gas is continuously supplied on the Si _1-x Ge _x layer, the sublimation of Ge is suppressed and the Si _1-x
The aggregation of Ge on the surface of the Ge _x layer and the roughening of the surface can be suppressed, and a high-quality Si layer can be obtained even in a process having a temperature increasing process.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view of a main part showing an epitaxial multilayer film in a method for manufacturing an epitaxial multilayer film and an embodiment of the epitaxial multilayer film according to the present invention.

FIG. 2 is a graph showing the results of analysis by SIMS when the supply of all the source gases is stopped during temperature rise and in the example of the present invention in the method for manufacturing an epitaxial multilayer film and the epitaxial multilayer film according to the present invention. .

FIG. 3 is an enlarged sectional view of a main part showing an epitaxial multilayer film according to another embodiment in the method for manufacturing an epitaxial multilayer film and the epitaxial multilayer film according to the present invention.

FIG. 4 is a diagram showing a time flow of temperature setting and flow rate setting of SiH ₄ and GeH ₄ in another embodiment in the method for manufacturing an epitaxial multilayer film and the epitaxial multilayer film according to the present invention.

FIG. 5 is a graph showing SIMS analysis results in a case where the supply of all the source gases is stopped at the time of temperature rise and in another embodiment of the present invention, in the method for manufacturing an epitaxial multilayer film and the epitaxial multilayer film according to the present invention. It is.

[Explanation of symbols]

SG Si _1-x Ge _x layer SG1 first Si _1-x Ge _x layer SG2 second Si _1-x Ge _x layer SI Si layer SI1 first Si layer SI2 second Si layer SUB Si substrate

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Eiji Kamiyama 1-297 Kitabukurocho, Omiya City, Saitama Prefecture Inside the Mitsubishi Materials Research Institute (72) Inventor Ichiro Shiono 1-297 Kitabukurocho Omiya City, Saitama Mitsubishi Materials 4G077 AA03 BA04 DB04 DB11 ED06 EF03 TB02 TC13 TK01

Claims (7)

[Claims] 1. The method according to claim 1, wherein the Si substrate is made of Si._1-xGe_xLayer and Si layer
Epitaxial growth to produce epitaxial multilayer
A source gas of Si and a source gas of Ge on the Si substrate.
To supply the Si _1-xGe_xEpitaxial growth of layers
Si_1-xGe_xA layer forming step;_1-xGe_xThe film forming temperature is higher than the layer forming step.
Si_1-xGe_xSupplying a source gas of Si onto the layer
forming a Si layer for epitaxially growing an i-layer.
In the Si layer forming step, the temperature is increased to the high film forming temperature.
A temperature raising step for raising the temperature_1-xG
e_xStop supply of Ge source gas at the end of layer formation process
The source gas of Si while heating
Note Si_1-xGe_xCharacterized by continuous supply on the bed
A method for manufacturing a epitaxial multilayer film. 2. The method for manufacturing an epitaxial multilayer film according to claim 1, wherein in the Si layer forming step, a flow rate of the Si source gas is set to a flow rate required at the high film forming temperature during the temperature raising step. A method for producing an epitaxial multilayer film, wherein the temperature is gradually changed. 3. The method for manufacturing an epitaxial multilayer film according to claim 1, wherein the Si _1-x Ge _x layer forming step includes setting the Ge composition ratio x of the Si _1-x Ge _x layer to 0.05. ≦ x ≦ 0.3 and Si
Method for manufacturing an epitaxial multilayer film, which comprises the _1-x Ge _x layer having a thickness of t and 0 <t ≦ 1 [mu] m. 4. A method for producing an epitaxial multilayer film according to any one of claims 1 to 3, wherein the Si _1-x Ge _x layer forming step, GeH ₄ or Ge ₂ H ₆
Is used as a Ge source gas and SiH ₄ ,
SiH ₂ Cl ₂ or Si ₂ H by a low pressure CVD either as a source gas of Si ₆ growing the Si _1-x Ge _x layer, the Si layer formation step, SiH _4, SiH ₂ Cl ₂ or S
A method for producing an epitaxial multilayer film, comprising growing the Si layer by low pressure CVD using i ₂ H ₆ as a Si source gas. 5. The method for producing an epitaxial multilayer film according to claim 1, wherein the Si _1-x Ge _x layer contains C, and the C composition ratio y is 0 <y ≦ 0. 05. A method for producing an epitaxial multilayer film, the method comprising: 6. The method for manufacturing an epitaxial multilayer film according to claim 5, wherein the step of forming the Si _1-x Ge _x layer includes SiH ₃ CH ₃ , SiH
_{2 (CH 3) 2, CH} 4 or method for manufacturing an epitaxial multilayer film, characterized in that one of the C ₂ H ₂ for growing the Si _1-x Ge _x layer by a low pressure CVD as a source gas of C. 7. S grown epitaxially on a Si substrate
an epitaxial multilayer film having i _1-x Ge _x layer and the Si layer, the epitaxial multilayer film, which has been produced by the method for producing an epitaxial multilayer film according to any one of claims 1 to 6.