Summary of the invention
The purpose of this invention is to provide SiGe virtual substrate of the high Ge content of a kind of relaxation and preparation method thereof, shortcomings such as, rough surface big, complex process with the thickness that overcomes high Ge content SiGe virtual substrate prepared in the prior art.A kind of mode with Ge content in the reverse gradual change SiGe component provided by the invention has prepared high-quality SiGe virtual substrate, and this virtual substrate has high Ge content, complete characteristics such as low, the thin thickness of relaxation, dislocation density, surfacing.
In order to solve the problems of the technologies described above, technical scheme of the present invention is following:
A kind of relaxation SiGe virtual substrate; Said SiGe virtual substrate comprises the Si substrate, on the Si substrate SiGe resilient coating and the constant SiGe layer of component of epitaxially grown successively from inside to outside Ge seed layer, Ge resilient coating, component-gradient, said Ge seed layer and said Ge resilient coating are formed the Ge relaxed buffer layers.
Each epitaxially grown layer is the resilient coating of complete deformation relaxation on the said Si substrate.
Dislocation in the SiGe virtual substrate of the high Ge content of said relaxation and defective mainly concentrate in the SiGe resilient coating of component-gradient, have lower dislocation and defect concentration (<10 in the constant SiGe layer of component
6Cm
-2).
The molar content of germanium is Ge% >=70% in the said relaxation SiGe virtual substrate, is the SiGe virtual substrate of high Ge content.
The mean roughness of said relaxation SiGe virtual substrate is 1.3-1.9nm, be lower than the prior art processes level requirement (<2.0nm).Through the dislocation density after the SiGe virtual substrate of the high Ge content of the said relaxation of etching 10
6Cm
-2Magnitude, satisfy the requirement of process for fabricating semiconductor device to substrate.
The Si substrate adopts the Si wafer in the said SiGe virtual substrate; Said Si wafer is standard-sized industrialization wafer, and the size of this Si wafer is selected from 4 inches, 6 inches, 8 inches, 12 inches equidimension specifications.
Ge seed layer and Ge resilient coating are formed the Ge relaxed buffer layer of complete relaxation in the said SiGe virtual substrate; The thickness of said Ge seed layer is 50-100nm, and the thickness of said Ge resilient coating is 300-600nm, and the thickness of said whole Ge relaxed buffer layer is 350-700nm.
Component is Si and Ge in the constant SiGe layer of the SiGe resilient coating of said component-gradient and component, its separately content be molar content.
In the SiGe resilient coating of said component-gradient; Be starting point, be terminal point with the side of next-door neighbour's Ge relaxed buffer layers with the side of the constant SiGe layer of next-door neighbour's component, the molar content of Ge from 100% be gradually reduced to the constant SiGe layer of component the Ge molar content identical.In the SiGe of described component-gradient resilient coating, the Ge content of the every 200-250nm varied in thickness 5% of the molar content of said Ge.
As; The molar content of the Ge of the SiGe resilient coating of said component-gradient is along with the increase of the SiGe buffer layer thickness of component-gradient; Be gradient to 95% since 100%, be gradient to 90% from 95%, by that analogy; Every 200-250nm thickness reduces by 5% Ge content, until be gradient to the constant SiGe layer of the component that is close in the molar content of Ge identical.
The thickness of the SiGe layer that said component is constant is 500-1000nm, can regulate according to the thickness requirement of required virtual substrate.
But epitaxial growing strain Ge channel layer is to be used for the channel material of cmos device on the said SiGe component layer of constant.
The preparation method of the SiGe virtual substrate of the high Ge content of a kind of relaxation adopts the rpcvd method on the Si substrate, with GeH according to the composition of the SiGe virtual substrate of the high Ge content of described relaxation
4And SiH
2Cl
2For the gas phase predecessor, with H
2Be carrier gas each epitaxial loayer of growing successively.
The epitaxial growth of Ge seed layer and Ge resilient coating is all with GeH among the preparation method of the SiGe virtual substrate of the high Ge content of described relaxation
4Be the gas phase predecessor, the epitaxial growth of the SiGe layer that the SiGe resilient coating of said component-gradient and component are constant is all with GeH
4And SiH
2Cl
2Be the gas phase predecessor.
This preparation method specifically comprises the steps:
1) epitaxial growth Ge seed layer on the Si substrate, the growth temperature of described Ge seed layer is 350-400 ℃, and growth room's pressure is 50-150Torr, and the thickness of growth is 50-100nm.
The growth of described Ge seed layer is with GeH
4Be the gas phase predecessor, flow velocity is 100-200sccm, with H
2Be carrier gas.
2) epitaxial growth Ge resilient coating on the good Ge seed layer of growth, the growth temperature of described Ge resilient coating is 650-700 ℃, and growth room's pressure is 50-150Torr, and the thickness of growth is 300-600nm.
The growth of described Ge resilient coating is with GeH
4Be the gas phase predecessor, flow velocity is 100-200sccm, with H
2Be carrier gas.
3) after said step 2) Ge buffer growth is accomplished in the growth room in-situ annealing, annealing temperature is 800-900 ℃, obtains the Ge relaxed buffer layers of complete relaxation.
The thickness of described Ge relaxed buffer layers is 350-700nm, can regulate according to the thickness requirement of required virtual substrate;
Described annealing time is as being 10 minutes.
4) the SiGe resilient coating of epitaxial growth component-gradient on the good Ge relaxed buffer layers of growth, described epitaxial growth temperature is 800-900 ℃, growth room's pressure is 20-100Torr.
The growth of the SiGe resilient coating of said component-gradient is with H
2Be carrier gas, with GeH
4And SiH
2Cl
2Be the gas phase predecessor, through the said gas phase predecessor of dynamic adjustments in epitaxial process GeH
4And SiH
2Cl
2Flow velocity recently prepare.
5) the constant SiGe layer of epitaxial growth component on the SiGe resilient coating of the good component-gradient of growth, described epitaxial growth temperature is 800-900 ℃, and growth room's pressure is 20-100Torr, and the thickness of growth is 500-1000nm.
The constant SiGe layer of described component is with H
2Be carrier gas, with GeH
4And SiH
2Cl
2Be gas phase predecessor, GeH
4Flow be 300-500sccm, SiH
2Cl
2Flow be 14-80sccm;
Wherein said SiH
2Cl
2Flow be preferably 14-62sccm.
Among the preparation method of the SiGe virtual substrate of the high Ge content of relaxation of the present invention; Wherein said whole Ge relaxed buffer layers is the necessary condition for the SiGe resilient coating of epitaxial growth component-gradient, and therefore obtaining the Ge relaxed buffer layers also is one of key factor that influences the virtual substrate quality.The epitaxial growth temperature of Ge seed layer can not be low excessively in the whole Ge relaxed buffer layers, otherwise polycrystalline growth can take place, and the thickness of whole Ge relaxed buffer layers can be regulated according to the thickness requirement of virtual substrate within the specific limits;
The SiGe resilient coating of wherein said component-gradient is the most critical part of high-quality SiGe virtual substrate of the present invention; Increase along with the SiGe buffer layer thickness of component-gradient; Every 200-250nm thickness is realized the variation of 5%Ge content in the SiGe resilient coating of component-gradient; Too fast or slow excessively Ge component-gradient rate is very big to the influence of virtual substrate quality and gross thickness, and this resilient coating is the zone of dislocation and defective in the restriction virtual substrate;
The constant SiGe resilient coating of wherein said component is the resilient coating of complete relaxation, and general epitaxial growth at high temperature can obtain the SiGe layer of complete relaxation, and epitaxial growth temperature is 800-900 ℃, and low-temperature epitaxy then needs annealing process, and growth rate is slow.
The SiGe virtual substrate of the high Ge content of relaxation of the present invention; Through introducing the Ge relaxed buffer layers that Ge seed layer and Ge resilient coating are formed; Adopt the content of Ge in the SiGe resilient coating of reverse gradual change component-gradient to limit dislocation and defective, be particularly suitable for preparing the thin SiGe virtual substrate of high Ge content.Adopt preparation method of the present invention not only can obtain the SiGe virtual substrate of the high Ge content of thinner thickness; Reduced simultaneously the surface roughness and the dislocation density of this SiGe virtual substrate effectively, do not needed extra processing technology, like CMP etc.; Shorten the extension time, saved cost.The high-quality SiGe virtual substrate that the present invention is prepared has high Ge content, complete characteristics such as low, the thin thickness of relaxation, dislocation density, surfacing, has reached the application requirements of device level strain Ge channel material.
Embodiment
Further set forth the present invention below in conjunction with specific embodiment, should be understood that these embodiment only are used to the present invention is described and are not used in restriction protection scope of the present invention.
Embodiment 1
A kind of preparation flow of SiGe virtual substrate of high Ge content is as shown in Figure 1, with preparation Si
0.2Ge
0.8Virtual substrate is an example, may further comprise the steps:
Step s100, the Si wafer of preparing four 4 inches, 6 inches, 8 inches and 12 inches respectively is as the Si substrate.
Step s101, the growth of Ge relaxed buffer layers: the Si substrate with 4 inches, 6 inches, 8 inches and 12 inches is the basis respectively, earlier at 400 ℃ with GeH
4Be gas phase predecessor, GeH
4Flow is 150sccm, with H
2Be carrier gas, growth room's pressure is 100Torr, and depositing a layer thickness respectively is the Ge seed layer of 50nm, 60nm, 100nm and 100nm; Keep growth atmosphere constant; Then on four good Ge seed layer of deposition 700 ℃ respectively deposit thickness be the Ge resilient coating of 300nm, 340nm, 400nm and 600nm; All annealed 10 minutes after the completion in 850 ℃ of original positions (epitaxial chamber); Keeping growth room's pressure during annealing is 100Torr, obtains the Ge relaxed buffer layers of four complete deformation relaxations.These four Ge relaxed buffer layers are respectively the Ge relaxed buffer layers of 4 inches Si substrate 350nm thickness; Be labeled as the Ge relaxed buffer layers of a1,6 inches Si substrate 400nm thickness; Be labeled as the Ge relaxed buffer layers of b1,8 inches Si substrate 500nm thickness; Be labeled as the Ge relaxed buffer layers of c1 and 12 inches Si substrate 700nm thickness, be labeled as d1.
Step s102, the growth of the SiGe resilient coating of component-gradient: on the basis of relaxation Ge resilient coating a1, b1, c1 and d1 that step s101 obtains, the SiGe resilient coating of difference epitaxial growth component-gradient is with H
2Be carrier gas, GeH
4And SiCl
2H
2Be the gas phase predecessor, growth temperature is 850 ℃, and growth room's pressure is 20Torr, with the variation of Ge content in the SiGe resilient coating of component-gradient, through regulating GeH
4With SiH
2Cl
2Flow-rate ratio realizes SiGe component-gradient, GeH
4Flow remain on 500sccm, SiCl
2H
2Flow cumulative with the growth time linearity.The every 250nm thickness of the SiGe resilient coating of component-gradient is realized the minimizing of 5%Ge, till the content ratio that is gradient to Ge and Si is 0.8: 0.2, obtains the Si that thickness is the component-gradient of 1000nm respectively
0.2Ge
0.8Resilient coating a2, b2, c2 and d2.
Step s103, the growth of the SiGe layer that component is constant: the Si of the component-gradient that obtains at step s102
0.2Ge
0.8On the basis of resilient coating a2, b2, c2 and d2, all with GeH
4And SiCl
2H
2Be gas phase predecessor, GeH
4Flow is 500sccm, SiCl
2H
2Flow is 33sccm, H
2Be carrier gas, epitaxial growth temperature is 850 ℃, and growth room's pressure is 20Torr, and growth thickness is the constant Si of the component of 500nm
0.2Ge
0.8Layer obtains SiGe virtual substrate a, b, c and the d of the high Ge content of relaxation respectively, is respectively 1850nm, 1900nm, 2000nm and 2200nm through the gross thickness that detects its epitaxial loayer.
The structural representation of the SiGe virtual substrate of the high Ge content of relaxation of this embodiment 1 gained is as shown in Figure 1; Be the basis with the Si substrate; The SiGe resilient coating of epitaxially grown successively from inside to outside Ge seed layer, Ge resilient coating, component-gradient and the constant SiGe layer of component, said Ge seed layer and said Ge resilient coating are formed the Ge relaxed buffer layer.
Fig. 2 is the Si of embodiment 1 gained
0.2Ge
0.8Virtual substrate c high-resolution X-ray diffraction reciprocal space collection of illustrative plates, epitaxially grown each layer marks in the drawings, can find out that complete deformation relaxation has taken place for Ge seed layer and Ge resilient coating, and SiGe component-gradient layer and SiGe component layer of constant also are in complete relaxed state.
Fig. 3 is the Si of embodiment 1 gained
0.2Ge
0.8Virtual substrate c cross-sectional transmission electron microscope (TEM) photo, the TEM photo from Fig. 3 can be found out Si
0.2Ge
0.8Each epitaxial loayer gross thickness of virtual substrate c is 2 μ m, and dislocation and defective mainly concentrate on the Si that thickness is 1 μ m
0-0.2Ge
1-0.8The component-gradient layer, Si
0.2Ge
0.8Then there are not tangible dislocation and defective in the component layer of constant.Need to prove the colloid that component is constant among Fig. 3 SiGe layer upper part used for the preparation sample for use in transmitted electron microscope in addition, with object of reference as top layer.
Fig. 4 is the Si of embodiment 1 gained
0.2Ge
0.8Surface atom force microscope (AFM) photo of virtual substrate c can be found out this Si from this surface topography atomic force photo
0.2Ge
0.8The mean roughness of virtual substrate c is 1.7 ± 0.1nm, be lower than the prior art processes level requirement (<2.0nm).
Fig. 5 is the Si of embodiment 1 gained
0.2Ge
0.8The optical microscope photograph of virtual substrate c after etching is through the Si that obtains after the etching
0.2Ge
0.8The dislocation density of virtual substrate is 1 * 10
6Cm
-2, satisfy the requirement of process for fabricating semiconductor device to substrate.
Embodiment 2
A kind of Si of high Ge content
0.15Ge
0.85The preparation of virtual substrate may further comprise the steps:
Step s100, the Si wafer of preparing 8 inches is as the Si substrate.
Step s101, the growth of Ge relaxed buffer layers: the Si substrate with 8 inches is the basis, earlier at 350 ℃ with GeH
4Be gas phase predecessor, GeH
4Flow is 200sccm, with H
2Be carrier gas, growth room's pressure is 100Torr, and depositing a layer thickness is the Ge seed layer of 100nm; Keep growth atmosphere constant; The Ge resilient coating that on the good Ge seed layer of deposition, is 400nm then at 650 ℃ of deposit thickness; Annealed 10 minutes in 850 ℃ of original positions (epitaxial chamber) after accomplishing; Keeping growth room's pressure during annealing is 100Torr, and acquisition thickness is the Ge relaxed buffer layers of 500nm, complete deformation relaxation.
Step s102, the growth of the SiGe resilient coating of component-gradient: on the relaxation Ge resilient coating basis that step s101 obtains, the SiGe resilient coating of epitaxial growth component-gradient is with H
2Be carrier gas, GeH
4And SiCl
2H
2Be the gas phase predecessor, growth temperature is 900 ℃, and growth room's pressure is 20Torr, with the increase of the SiGe buffer layer thickness of component-gradient, through regulating GeH
4With SiH
2Cl
2Flow-rate ratio realizes SiGe component-gradient, GeH
4Flow remain on 500sccm, SiCl
2H
2Flow cumulative with the growth time linearity.The every 200nm thickness of the SiGe resilient coating of component-gradient is realized the minimizing of 5%Ge, till the content ratio that is gradient to Ge and Si is 0.85: 0.15, obtains the Si that thickness is the component-gradient of 600nm
0.15Ge
0.85Resilient coating.
Step s103, the growth of the SiGe layer that component is constant: the Si of the component-gradient that obtains at step s102
0.15Ge
0.85On the resilient coating, with GeH
4And SiCl
2H
2Be gas phase predecessor, GeH
4Flow is 300sccm, SiCl
2H
2Flow is 18sccm, H
2Be carrier gas, epitaxial growth temperature is 800 ℃, and growth room's pressure is 50Torr, and growth thickness is the constant Si of the component of 500nm
0.15Ge
0.85Layer obtains the SiGe virtual substrate of the high Ge content of relaxation, is 1600nm through the gross thickness that detects its epitaxial loayer.
After testing; The SiGe virtual substrate of the high Ge content of relaxation of gained is the basis with the Si substrate; Comprise the SiGe cushion and the constant SiGe layer of component of epitaxially grown successively from inside to outside Ge relaxed buffer layer, component-gradient, said Ge relaxed buffer layer comprises Ge seed layer and Ge cushion from inside to outside.
Through detecting the Si of embodiment 2 gained
0.15Ge
0.85Virtual substrate high-resolution X-ray diffraction reciprocal space collection of illustrative plates can find out that complete deformation relaxation has taken place for Ge seed layer and Ge resilient coating, and SiGe component-gradient layer and SiGe component layer of constant also are in complete relaxed state.
Through detecting the Si of embodiment 2 gained
0.15Ge
0.85Virtual substrate cross-sectional transmission electron microscope (TEM) photo can be found out Si
0.15Ge
0.85Each epitaxial loayer gross thickness of virtual substrate is 1.6 μ m, and dislocation and defective mainly concentrate on the Si that thickness is 0.6 μ m
0-0.15Ge
1-0.85The component-gradient layer effectively reduces Si
0.15Ge
0.85Dislocation in the component layer of constant and defect concentration, the TEM photo shows Si
0.15Ge
0.85Then there are not tangible dislocation and defective in the component layer of constant.
Through detecting the Si of embodiment 2 gained
0.15Ge
0.85Surface atom force microscope (AFM) photo of virtual substrate can be found out this Si from this surface topography atomic force photo
0.15Ge
0.85The mean roughness of virtual substrate is 1.5 ± 0.1nm, be lower than the prior art processes level requirement (<2.0nm).
Through detecting the Si of embodiment 2 gained
0.15Ge
0.85The optical microscope photograph of virtual substrate after etching is through the Si that obtains after the etching
0.15Ge
0.85The dislocation density of virtual substrate is 6 * 10
6Cm
-2, satisfy the requirement of process for fabricating semiconductor device to substrate.
Embodiment 3
A kind of Si of high Ge content
0.1Ge
0.9The preparation of virtual substrate may further comprise the steps:
Step s100, the Si wafer of preparing 6 inches is as the Si substrate.
Step s101, the growth of Ge relaxed buffer layers: the Si substrate with 6 inches is the basis, earlier at 400 ℃ with GeH
4Be gas phase predecessor, GeH
4Flow is 100sccm, with H
2Be carrier gas, growth room's pressure is 50Torr, and depositing a layer thickness is the Ge seed layer of 100nm; Keep growth atmosphere constant; The Ge resilient coating that on the good Ge seed layer of deposition, is 500nm then at 650 ℃ of deposit thickness; Annealed 10 minutes in 800 ℃ of original positions (epitaxial chamber) after accomplishing; Keeping growth room's pressure during annealing is 100Torr, and acquisition thickness is the Ge relaxed buffer layers of 600nm, complete deformation relaxation.
Step s102, the growth of the SiGe resilient coating of component-gradient: on the relaxation Ge resilient coating basis that step s101 obtains, the SiGe resilient coating of epitaxial growth component-gradient is with H
2Be carrier gas, GeH
4And SiCl
2H
2Be the gas phase predecessor, growth temperature is 800 ℃, and growth room's pressure is 100Torr, with the increase of the SiGe buffer layer thickness of component-gradient, through regulating GeH
4With SiH
2Cl
2Flow-rate ratio realizes SiGe component-gradient, GeH
4Flow remain on 300sccm, SiCl
2H
2Flow cumulative with the growth time linearity.The every 250nm thickness of the SiGe resilient coating of component-gradient is realized the minimizing of 5%Ge, till the content ratio that is gradient to Ge and Si is 0.9: 0.1, obtains the Si that thickness is the component-gradient of 500nm
0.1Ge
0.9Resilient coating.
Step s103, the growth of the SiGe layer that component is constant: the Si of the component-gradient that obtains at step s102
0.1Ge
0.9On the resilient coating, with GeH
4And SiCl
2H
2Be gas phase predecessor, GeH
4Flow is 500sccm, SiCl
2H
2Flow is 14sccm, H
2Be carrier gas, epitaxial growth temperature is 900 ℃, and growth room's pressure is 100Torr, and growth thickness is the constant Si of the component of 1000nm
0.1Ge
0.9Layer obtains the SiGe virtual substrate of the high Ge content of relaxation, is 2100nm through the gross thickness that detects its epitaxial loayer.
After testing; The SiGe virtual substrate of the high Ge content of relaxation of gained is the basis with the Si substrate; Comprise the SiGe cushion and the constant SiGe layer of component of epitaxially grown successively from inside to outside Ge relaxed buffer layer, component-gradient, said Ge relaxed buffer layer comprises Ge seed layer and Ge cushion from inside to outside.
Through detecting the Si of embodiment 3 gained
0.1Ge
0.9Virtual substrate high-resolution X-ray diffraction reciprocal space collection of illustrative plates can find out that complete deformation relaxation has taken place for Ge seed layer and Ge resilient coating, and SiGe component-gradient layer and SiGe component layer of constant also are in complete relaxed state.
Through detecting the Si of embodiment 3 gained
0.1Ge
0.9Virtual substrate cross-sectional transmission electron microscope (TEM) photo can be found out Si
0.1Ge
0.9Each epitaxial loayer gross thickness of virtual substrate is 2.1 μ m, and dislocation and defective mainly concentrate on the Si that thickness is 0.5 μ m
0-0.1Ge
1-0.9The component-gradient layer effectively reduces Si
0.1Ge
0.9Dislocation in the component layer of constant and defect concentration, the TEM photo shows Si
0.1Ge
0.9Then there are not tangible dislocation and defective in the component layer of constant.
Through detecting the Si of embodiment 3 gained
0.1Ge
0.9Surface atom force microscope (AFM) photo of virtual substrate can be found out this Si from this surface topography atomic force photo
0.1Ge
0.9The mean roughness of virtual substrate is 1.4 ± 0.1nm, be lower than the prior art processes level requirement (<2.0nm).
Through detecting the Si of embodiment 3 gained
0.1Ge
0.9The optical microscope photograph of virtual substrate after etching is through the Si that obtains after the etching
0.1Ge
0.9The dislocation density of virtual substrate is 8.5 * 10
6Cm
-2, satisfy the requirement of process for fabricating semiconductor device to substrate.
Embodiment 4
A kind of Si of high Ge content
0.25Ge
0.75The preparation of virtual substrate may further comprise the steps:
Step s100, the Si wafer of preparing 12 inches is as the Si substrate.
Step s101, the growth of Ge relaxed buffer layers: the Si substrate with 12 inches is the basis, earlier at 400 ℃ with GeH
4Be gas phase predecessor, GeH
4Flow is 150sccm, with H
2Be carrier gas, growth room's pressure is 150Torr, and depositing a layer thickness is the Ge seed layer of 100nm; Keep growth atmosphere constant; The Ge resilient coating that on the good Ge seed layer of deposition, is 400nm then at 700 ℃ of deposit thickness; Annealed 10 minutes in 900 ℃ of original positions (epitaxial chamber) after accomplishing; Keeping growth room's pressure during annealing is 100Torr, and acquisition thickness is the Ge relaxed buffer layers of 500nm, complete deformation relaxation.
Step s102, the growth of the SiGe resilient coating of component-gradient: on the relaxation Ge resilient coating basis that step s101 obtains, the SiGe resilient coating of epitaxial growth component-gradient is with H
2Be carrier gas, GeH
4And SiCl
2H
2Be the gas phase predecessor, growth temperature is 850 ℃, and growth room's pressure is 50Torr, with the increase of the SiGe buffer layer thickness of component-gradient, through regulating GeH
4With SiH
2Cl
2Flow-rate ratio realizes SiGe component-gradient, GeH
4Flow remain on 500sccm, SiCl
2H
2Flow cumulative with the growth time linearity.The every 200nm thickness of the SiGe resilient coating of component-gradient is realized the minimizing of 5%Ge, till the content ratio that is gradient to Ge and Si is 0.75: 0.25, obtains the Si that thickness is the component-gradient of 1000nm
0.25Ge
0.75Resilient coating.
Step s103, the growth of the SiGe layer that component is constant: the Si of the component-gradient that obtains at step s102
0.25Ge
0.75On the resilient coating, with GeH
4And SiCl
2H
2Be gas phase predecessor, GeH
4Flow is 400sccm, SiCl
2H
2Flow is 62sccm, H
2Be carrier gas, epitaxial growth temperature is 850 ℃, and growth room's pressure is 20Torr, and growth thickness is the constant Si of the component of 500nm
0.25Ge
0.75Layer obtains the SiGe virtual substrate of the high Ge content of relaxation, is 2000nm through the gross thickness that detects its epitaxial loayer.
After testing; The SiGe virtual substrate of the high Ge content of relaxation of gained is the basis with the Si substrate; Comprise the SiGe cushion and the constant SiGe layer of component of epitaxially grown successively from inside to outside Ge relaxed buffer layer, component-gradient, said Ge relaxed buffer layer comprises Ge seed layer and Ge cushion from inside to outside.
Through detecting the Si of embodiment 4 gained
0.25Ge
0.75Virtual substrate high-resolution X-ray diffraction reciprocal space collection of illustrative plates can find out that complete deformation relaxation has taken place for Ge seed layer and Ge resilient coating, and SiGe component-gradient layer and SiGe component layer of constant also are in complete relaxed state.
Through detecting the Si of embodiment 4 gained
0.25Ge
0.75Virtual substrate cross-sectional transmission electron microscope (TEM) photo can be found out Si
0.25Ge
0.75Each epitaxial loayer gross thickness of virtual substrate is 2 μ m, and dislocation and defective mainly concentrate on the Si that thickness is 1 μ m
0-0.25Ge
1-0.75The component-gradient layer effectively reduces Si
0.25Ge
0.75Dislocation in the component layer of constant and defect concentration, the TEM photo shows Si
0.25Ge
0.75Then there are not tangible dislocation and defective in the component layer of constant.
Through detecting the Si of embodiment 4 gained
0.25Ge
0.75Surface atom force microscope (AFM) photo of virtual substrate can be found out this Si from this surface topography atomic force photo
0.25Ge
0.75The mean roughness of intending substrate is 1.8 ± 0.1nm, be lower than the prior art processes level requirement (<2.0nm).
Through detecting the Si of embodiment 4 gained
0.25Ge
0.75The optical microscope photograph of virtual substrate after etching is through the Si that obtains after the etching
0.25Ge
0.75The dislocation density of virtual substrate is 1.5 * 10
6Cm
-2, satisfy the requirement of process for fabricating semiconductor device to substrate.