JP2002094034A - Soi substrate and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control an Si layer which is suitable for mass production which has a simple manufacturing process. SOLUTION: An SOI substrate 10 comprises a silicon substrate 11, an Si1-xGexO2 layer 12 (where 0<=x<=0.5) formed on a surface of the substrate 11, and an Si layer 13 formed on the surface of the layer 12. This substrate 10 is manufactured by epitaxially growing an Si1-yGey layer 14 (where 0.05<=y<=0.75), depositing the Si1-yGey layer 14 on the surface of the substrate 11, epitaxially growing an Si layer 13, depositing the layer 3 on a surface of the layer 14, further thermally oxidizing the substrate 11, in which the layer 14 and the layer 13 are deposited, and causing the layer 14 to change into an Si1-xGexO2 layer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an SOI (Silicon-On-Insulator) substrate having an Si layer formed on an insulating layer and a method of manufacturing the same.

[0002]

2. Description of the Related Art An SOI substrate of this type has a very high integrated circuit (U.S.A.).
(LSI) substrates are drawing attention. This SOI substrate manufacturing method includes a method in which silicon substrates are bonded to each other via an insulating layer, a method in which high-concentration oxygen ions are implanted into a silicon substrate, and then an annealing treatment is performed at a high temperature to perform a predetermined process from the surface of the silicon substrate. A buried silicon oxide layer is formed in a region having a depth, and the Si layer on the surface thereof is used as an active region.
IMOX method (Japanese Patent Application Laid-Open No. Hei 7-263538), after hydrogen ions are implanted into a silicon substrate, the silicon substrate is bonded to a support substrate with the ion-implanted surface as a superposed surface, and the laminate is heated to a temperature exceeding 500 ° C. A hydrogen ion implantation separation method for forming a Si layer on the surface of the support substrate by separating the silicon substrate from the support substrate in a region where hydrogen ions are implanted by heating (JP-A-5-211128); An SiO ₂ layer is formed via a porous Si layer and a Si single crystal layer, and the silicon substrate is bonded to a support substrate with the SiO ₂ layer as an overlapping surface. High pressure water flow separation method (T.Yoneyama, US Patent, 537
1037, US filed: August 9.1991, US patented December
6.1994).

[0003]

However, in the above-mentioned conventional bonding method, SIMOX method, hydrogen ion implantation separation method and high-pressure water flow separation method, the thickness of the Si layer is 2 μm or more and 0.05 to 0.2 μm, respectively. , 0.2-2 μm and 0.2
There was a problem limited to the range of about 2 μm. Further, the conventional bonding method, hydrogen ion implantation separation method and high-pressure water flow separation method have a problem that the production process is relatively complicated and the number of steps is increased. Further, the conventional SIMOX method has a problem that the roughness of the interface between the silicon oxide layer and the Si layer is relatively large.

A first object of the present invention is to provide a method for manufacturing an SOI substrate which has a simple manufacturing process and is suitable for mass production. A second object of the present invention is to provide a Si layer and an S layer.
The interface of the i _1-x Ge _x O ₂ layer can be smoothed.
An object of the present invention is to provide an OI substrate and a method for manufacturing the same. A third object of the present invention is to provide an SOI substrate and a method of manufacturing the same, which can easily manage particles and metal contamination.

[0005]

The invention according to claim 1 is
As shown in FIG. 1, a silicon substrate 11, a Si _1-x Ge _x O ₂ layer 12 (0 ≦ x ≦ 0.5) formed on the surface of the silicon substrate 11, and a Si _1-x Ge _x This is an SOI substrate including an O ₂ layer 12 and a Si layer 13 formed on the surface.
In the SOI substrate according to the first aspect, the Si layer 13
The interface between the Si _1-x Ge _x O ₂ layer 12 and the Si layer 13 is smooth.
The SOI substrate 10 has a uniform thickness.

The invention according to claim 2 is as shown in FIG.
Then, a silicon substrate 11_1-yGe_yLayer 14 (however
And 0.05 ≦ y ≦ 0.75)
And depositing the Si_1-yGe_ySi layer on the surface of layer 14
13 by epitaxially growing and depositing Si;
_1-yGe_ySilicon substrate on which layer 14 and Si layer 13 are deposited
11 by thermal oxidation_1-yGe_yLayer 14
Oxidized to Si_1-xGe_xO _TwoLayer 12 (where 0 ≦ x ≦ 0.
5) a method for manufacturing an SOI substrate, the method including:
Oh, Si_1-yGe_yIntroduce oxygen gas during deposition of layer 14
By doing_1-yGe_yLayer 14 should contain oxygen.
And features. 3. The SOI substrate according to claim 2.
In the manufacturing method, the conventional bonding method, hydrogen ion implantation
Compared to the separation method and the high-pressure water separation method,
Simple, suitable for mass production, and can reduce manufacturing costs
it can. Also Si_1-yGe_yLayer 14 and Si layer 13 are LP
Uniform for epitaxial growth by CVD method etc.
And can be deposited without limiting the thickness.
Forming a good (very few crystal defects) Si layer 13
Can be Also, because the manufacturing process is simple,
Manages particles and metal contamination in SOI substrate 10
It can be done easily. Furthermore, Si_1-yGe_yOxygen in layer 14
Contains Si_1-yGe_yLayer 14 oxidizes quickly
Being Si_1-xGe_xO_TwoIt becomes layer 12.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIG.
Comprises a silicon substrate 11, a Si _1-x Ge _x O ₂ layer 12 formed on the surface of the silicon substrate 11, and a Si layer 13 formed on the surface of the Si _1-x Ge _x O ₂ layer 12. Each of the silicon substrate 11 and the Si layer 13 is a single crystal. The number x of Ge atoms in Si _1-x Ge _x O ₂ of the Si _1-x Ge _x O ₂ layer 12 is 0 ≦ x ≦ 0.5, preferably 0 ≦ x ≦ 0.5.
x ≦ 0.05 is set. The reason why x is limited to the above range is that if it exceeds 0.5, the withstand voltage of the oxide film decreases. Note that the Si _1-x Ge _x O ₂ layer 12 is preferably an SiO ₂ layer in which x is zero as an insulating layer.

A method for manufacturing the SOI substrate 10 having the above-described structure will be described. First, the silicon substrate 11 (plane orientation (0
01) or (111) single crystal substrate) on the surface, low pressure chemical vapor deposition (LPCVD), ultra-high vacuum chemical vapor deposition (UHV-CVD), gas source molecular beam epitaxy (GSMBE), Molecular beam epitaxy (MBE
The Si _1-y Ge _y layer 14 is epitaxially grown and deposited by the method (FIG. 1B). Where Si _1-y G
The number y of Ge atoms in Si _1-y Ge _y of the e _y layer 14 is 0.05 ≦ y ≦ 0.75, preferably 0.1 ≦ y ≦ 0.
Set to 5. The reason why y is limited to the above range is that 0.0
If it is less than 5, the effect of the present invention, in particular, the presence of germanium, oxidizes the region which was the Si _1-y Ge _y layer 14 by heat treatment and changes to the Si _1-x Ge _x O ₂ layer 12 which is an insulating layer. There is a problem that it is difficult to obtain the effect that it is easy to
If it exceeds 0.75, there is a problem that defects are likely to occur. Also, the Si _1-y Ge _y layer 1 by the LPCVD method
The film forming conditions of 4 are such that the temperature is 600 to 800 ° C. and the pressure is 20 to
100 Torr, hydrogen flow rate is 10~50slm (standard liters / min), SiH ₄ flow rate 20~500sccm (standard cc
/ Min), and the GeH ₄ flow rate is preferably 0.01 to 20 sccm.

[0009] Then LP in the Si _1-y Ge _y layer 14 surface
CVD, ultra-high vacuum chemical vapor deposition (UHV-CVD)
Method), gas source molecular beam epitaxy method (GSMBE)
Method), molecular beam epitaxy method (MBE method), etc.
Layer 13 is epitaxially deposited and deposited (FIG. 1).
(C)). Here, the conditions for forming the Si layer 13 by the LPCVD method are as follows: a temperature of 600 to 1000 ° C. and a pressure of 20 to 100 ° C.
Torr, hydrogen flow rate is 10-50 slm, SiH ₄ flow rate is 20-
Preferably it is 500 sccm. In forming the Si layer 13, a source gas such as SiH ₂ Cl ₂ or Si ₂ H ₆ may be used. By introducing oxygen (O ₂ ) gas during the epitaxial growth of the Si _1-y Ge _y layer 14, the Si _1-y Ge _y layer 1
In the step of including an oxygen in 4, it is preferable that the content of oxygen in the Si _1-y Ge _y layer 14 is to introduce oxygen gas so that ^{1 × 10 20 ~2 × 10 22} atoms / cc.

Next, the silicon substrate 11 is heat-treated in a thermal oxidation furnace. The conditions for this heat treatment are preferably as follows. First, 700-900 in an inert gas atmosphere
The silicon substrate is placed in a thermal oxidation furnace that has been heated to a predetermined temperature in the range of ° C. Then, in an inert gas atmosphere or an oxygen atmosphere containing 1 to 100% by volume of oxygen, the temperature is raised to a predetermined temperature of 1300 to 1350 ° C. at a rate of 2 to 10 ° C./min and kept at this temperature for 0 to 5 hours. I do. Next, 1300-1350
While maintaining a predetermined temperature in the range of ° C., the inside of the furnace is set to a 100% by volume oxygen atmosphere, and is maintained for 1 to 5 hours. 1300
1 to 1350 ° C.
After returning to an inert gas atmosphere containing 00% by volume of oxygen,
Alternatively, the temperature is lowered to a predetermined temperature of 700 to 900 ° C. at a temperature lowering rate of 2 to 10 ° C./min in an oxygen atmosphere. This heat treatment oxidizes the region that was the Si _1-y Ge _y layer 14 to change to the Si _1-x Ge _x O ₂ layer 12 which is an insulating layer, and also formed a surface oxide layer 15 (SiO ₂ Layer) is formed (FIG. 1D). The SOI substrate 10 is HF
By etching to remove the surface oxide film 15,
The manufacture of the SOI substrate 10 is completed (FIG. 1E).

The manufacturing method of such an SOI substrate 10 has a simple manufacturing process, is suitable for mass production, and reduces the manufacturing cost, as compared with the conventional bonding method, hydrogen ion implantation separation method and high pressure water flow separation method. be able to. Also Si
For epitaxially grown by the _1-y Ge _y layer 14 and the Si layer 13 LPCVD method or the like, can be uniformly deposited. As a result, the Si layer 13 can be controlled accurately and in a wide thickness range, and the Si layer 13 and the Si _1-x Ge _x O ₂ layer 1 can be controlled.
2 can be smoothed, and the Si layer 13 having good crystallinity (very few crystal defects) can be formed. In addition, because the manufacturing process is simple, SO
It is possible to easily manage particles and metal contamination in the I-substrate 10.

[0012]

Next, embodiments of the present invention will be described in detail. <Embodiment 1> As shown in FIG.
(Single-crystal substrate with plane orientation (001)) A Si _1-y Ge _y layer 14 (provided that 0.05 ≦ y ≦ 0.
75) was epitaxially grown and deposited (FIG. 1).
(B)). The conditions for forming the Si _1-y Ge _y layer 14 are as follows: temperature 780 ° C., pressure 50 Torr, hydrogen flow rate 50 slm, Si
The H ₄ flow rate was 30 sccm and the GeH ₄ flow rate was 5.7 sccm. Next, a Si layer 13 was epitaxially grown and deposited on the surface of the Si _1-y Ge _y layer 14 by the LPCVD method (FIG. 1C). The conditions for forming the Si layer 13 are as follows.
80 ° C, pressure 50 Torr, hydrogen flow 50 liter / sc
cm and the SiH ₄ flow rate was 60 sccm. Where Si _1-y G
(By observing the elliptically polarized light reflected by the object surface, a method of examining the thickness of the layer or a thin film deposited on the object itself and the object surface) thickness spectroscopic ellipsometry e _y layer 14 and the Si layer 13 as measured by After that, each 0.1
They were 2 μm and 0.4 μm. The Si _1-y Ge _y layer 1
The Ge concentration in Sample No. 4 was measured by spectroscopic ellipsometry and found to be 30 atomic%. Further, the Si _1-y Ge _y layer 14
By introducing oxygen (O ₂ ) gas during the epitaxial growth of oxygen, oxygen is introduced into the Si _1-y Ge _y
²⁰ atoms / cc.

Next, the silicon substrate 11 was heat-treated in a thermal oxidation furnace. The conditions of this heat treatment were as follows. First, the silicon substrate was placed in a thermal oxidation furnace heated to 800 ° C. in an argon gas atmosphere, and then the gas was replaced with an argon gas atmosphere containing 1.5% by volume of oxygen. Then 5
The temperature was raised to 1320 ° C at a rate of
The atmosphere in the furnace was kept at 100% by volume in an atmosphere of oxygen and kept for 4 hours. After the furnace was returned to an argon gas atmosphere containing 1.5% by volume of oxygen while maintaining the temperature at 1350 ° C., the temperature was lowered to 800 ° C. at a rate of 5 ° C./min.
When the silicon substrate 11 after the heat treatment was analyzed as described below, the region that was the Si _1-y Ge _y layer 14 became the SiO ₂ layer (x was substituted for x of the Si _1-x Ge _x O ₂ layer 12). The surface oxide layer 15 (SiO ₂ layer) on the surface of the Si layer 13
Was observed (FIG. 1 (d)). However, the region which was the Si layer 13 between the SiO ₂ layer and the surface oxide layer 15 was kept in the Si layer 13 having good crystallinity (very few crystal defects).

With respect to the SOI substrate 10, the surface oxide layer 15, the Si layer 13, and the SiO
_When the thickness of the _two layers was measured, each was 0.5 μm,
They were 0.1 μm and 0.27 μm. Further, when 21 points were measured in the plane of the SOI substrate 10 by spectroscopic ellipsometry, the thicknesses of the respective layers were substantially uniform, and the error was about 1%. The SOI substrate 10 was subjected to HF etching after being subjected to Secco etching, and the distribution of crystal defects in the Si layer 13 was examined. As a result, good crystallinity with very few crystal defects was confirmed. Regarding the crystallinity of the Si layer 13, the transmission electron microscope (TE
M) and the measurement of the SOI substrate 10 by X-ray topography.

Also, before removing the surface oxide layer 15,
The surface roughness of the SOI substrate 10 is measured by an atomic force microscope (AFM)
Was observed. On the other hand, SiO_TwoBetween the layer and the Si layer 13
The surface roughness of the interface oxide layer 15 is removed by HF etching.
And the Si layer 13 was removed by KOH etching.
Later, it was observed with an atomic force microscope. As a result, SO
Surface roughness of I-substrate 10 and SiO_TwoBetween layer and Si layer 13
The roughness of the interface was smooth. Also SOI substrate
SiO inside 10_TwoThe formation of the layer is secondary
Ion mass spectrometry (SIMS: several keV to 20 keV
Impacts small points on the surface of data with primary ions having energy
And sputter ionize the surface material and analyze by mass spectrometry
Can be confirmed by measuring the oxygen depth distribution
Was. Auger electron spectroscopy (AES:
Atoms are excited by radiating a probe beam onto the sample surface.
Emits Auger electrons and the spectrum of the Auger electrons
Of the element near the sample surface by measuring
Method) / X-ray photoelectron spectroscopy (ESCA: sample surface)
By irradiating characteristic X-rays to the
Analyzes the photoelectrons of the sample to determine the composition and
In the measurement by the method of _TwoLayer of stoichio
SiO whose measurement does not contain any Ge_TwoOnly stoichiometric values
Was confirmed.

[0016]

As described above, according to the present invention, the system
Si on the surface of the recon substrate_1-xGe_xO_TwoForming a layer, Si_1-x
Ge_xO_TwoSince the Si layer was formed on the layer surface, the Si layer and the S layer
i_1-xGe_xO_TwoThe interface of the layers is smooth and the thickness of the Si layer is uniform.
A good SOI substrate is obtained. Also on the silicon substrate surface
Si_1-yGe_yLayers are epitaxially deposited and
i_1-yGe_yEpitaxial growth of a Si layer on the layer surface
By depositing and thermally oxidizing the silicon substrate
Si_1-yGe_yOxidize the layer to Si_1-xGe_xO_TwoChanged into layers
And then Si_1-yGe_yIntroduce oxygen gas during layer deposition
The Si _1-yGe_yIf oxygen is included in the layer,
The manufacturing process is simpler than the bonding method
Therefore, it is suitable for mass production and can reduce manufacturing cost.
Also Si_{1- y}Ge_yLayer and Si layer by LPCVD method etc.
Because of epitaxial growth, uniform deposition can be achieved. This
As a result, the Si layer can be accurately controlled and the Si layer
And Si_1-xGe_xO_TwoThe interface between layers can be smoothed
S with good crystallinity (very few crystal defects)
An i-layer can be formed. Simple manufacturing process
Therefore, particles and metal contamination in the SOI substrate
Management can be performed easily. Furthermore, Si_1-yGe_yIn layers
Because it contains oxygen, Si_1-yGe_yLayer oxidizes quickly
Being Si_1-xGe_xO_TwoLayer.

[Brief description of the drawings]

FIG. 1 is a process chart showing a procedure for manufacturing an SOI substrate according to an embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 SOI substrate 11 Silicon substrate 12 Si _1-x Ge _x O ₂ layer 13 Si layer 14 Si _1-y Ge _y layer 15 Surface oxide layer (SiO ₂ layer)

Claims (2)

[Claims] 1. A silicon substrate (11), and Si _1-x Ge _x O formed on a surface of the silicon substrate (11).
_Two layers (12) (provided that 0 ≦ x ≦ 0.5) and a Si layer (1) formed on the surface of the Si _1-x Ge _x O ₂ layer (12).
3) an SOI substrate comprising: 2. A silicon substrate (11) having a surface_1-yGe_ylayer
(14) (However, 0.05 ≦ y ≦ 0.75)
Depositing by growing the silicon;_1-yGe_yEpitaxy of Si layer (13) on layer (14) surface
A step of growing and depositing the silicon;_1-yGe_yDeposited layer (14) and said Si layer (13)
By subjecting the silicon substrate (11) to a thermal oxidation treatment,
Si_1-yGe_yOxidize layer (14) to Si_1-xGe_xO _TwoLayer (12)
(Where 0 ≦ x ≦ 0.5).
A method for manufacturing an OI substrate, comprising:_1-yGe_yIntroduce oxygen gas during the deposition of layer (14)
The Si_{1- y}Ge_yLayer (14) should contain oxygen.
And a method for manufacturing an SOI substrate.