JP4980049B2 - Relaxation of thin layers after transition - Google Patents

Description

  The present invention relates to the formation of relaxation or pseudo-relaxation layers on a substrate to form a final structure for electronics, optics, or optoelectronics, such as a semiconductor-on-insulator structure, where the relaxation layer is formed from a semiconductor material. Made with selected materials.

  The invention specifically includes the formation of a strained layer on and through the relaxation layer.

  For example, with respect to the above points, an Si layer distorted by a relaxed or pseudo-relaxed SiGe layer realizes interesting properties such as about 100% charge carrier mobility that is greater than the charge carrier mobility present in the relaxed Si layer. There is.

  As used herein, when a crystalline material comprising a layer has a lattice parameter that is approximately equal to its nominal lattice parameter, that is, a lattice parameter that is approximately equal to the lattice parameter of the material in its bulk equilibrium shape, the layer is "Relaxing".

  In the present specification, conversely, it is understood that the crystalline material constituting the layer is elastically strained by tension or compression during crystal growth such as epitaxy, so that the lattice parameter is significantly different from the nominal lattice parameter of the material. When forced, the layer is referred to as “distorted”.

Background of the Invention

In particular, methods are known for forming a relaxation layer on a substrate by applying a method comprising the following steps:
(1) epitaxy of a thin layer of semiconductor material on a donor substrate;
(2) Joining the receiving substrate in a thin layer;
(3) Removal of part of the donor substrate.

  A semiconductor-on-insulator structure may be fabricated by the method described above, in which case the semiconductor portion at least partially comprises or constitutes the relaxed thin layer, the insulator portion typically comprising steps (1) and step. (2) is formed in an intermediate step.

The production of thin layers is:
It may be achieved during the application of step (1); or

  In the first case, a method using a donor substrate consisting of a holding substrate and a buffer layer is known, and the buffer layer confines plastic deformation, so that the epitaxially grown thin layer relaxes from any strain. Is done. Such a method is described, for example, in patent documents US2002 / 0072130 and WO99 / 53539.

  However, manufacturing the buffer layer is often time consuming and expensive.

  In the second case, the donor substrate does not comprise a buffer layer, so step (1) involves the growth of a thin layer that will be distorted by the donor substrate.

  Thus, for example, the SiGe layer will grow directly on the Si substrate and on such a thickness that the SiGe layer is distorted throughout.

  In particular, B. Hollander et al., “Strain relaxation of pseudomorphic Si1-xGex / Si [100] heterostructures after hydrogen or helium ion implantation for virtual substrate fabrication. In the first SiGe layer relaxation technique described in “Nuclear and Instruments and Methods in Physics Research B175-177 [2001] 357-367]”, step (2) is performed. Before application, the SiGe layer is relaxed by implanting hydrogen or helium ions at a predetermined depth in the Si substrate.

  However, the relaxation rate normally obtained with the first technique is still slightly lower than other techniques.

  Research on the second technology is based on the literature by Hobart et al. “Compliant Substrates: A comparative study of the relaxation mechanisms of strained films bonded to high and low viscosity. (Journal of Electronic Materials, vol.29, No.7, 2000).

  After removing the donor substrate in step (3), heat treatment is performed to relax or pseudo-relax the strained SiGe layer bonded to the BPSG glass in step (2).

  Thus, during heat treatment, the strained layer appears to relax through the glass layer that is viscous at the temperature of the heat treatment.

  However, the latter technique involves relaxation of the SiGe thin layer when the SiGe thin layer is exposed.

  By the way, exposure (exposure) of such a SiGe layer to a gaseous atmosphere during heat treatment (room RTA treatment, sacrificial oxidation, recovery annealing, etc.) may end up with a serious disadvantage to the quality of the same layer. Ge contained in the same layer may diffuse significantly to the outside (and may lead to decomposition of the layer), and the same layer may be contaminated by foreign contaminants.

  Moreover, such a SiGe layer is on the surface, and therefore, it may be subjected to a treatment such as a finishing treatment (polishing, smoothing, oxidation, washing, etc.).

  By the way, those treatments for SiGe are not as advanced as those for Si.

  And the lack of control when handling SiGe, in turn, causes further difficulties in producing the desired structure.

The present invention attempts to overcome these difficulties by providing a method for forming a relaxation or pseudo relaxation layer on a substrate, the relaxation layer being a material selected from semiconductor materials, the method comprising: The following steps:
(A) growing an elastically strained layer of a material selected from semiconductor materials on a donor substrate;
(B) forming a vitreous layer made of a viscous material from a viscous temperature on the strained layer or on the receiving substrate;
(C) bonding the receiving substrate to the strained layer through the vitreous layer;
(D) removing a portion of the donor substrate, comprising a receiving substrate, a vitreous layer, a strained layer, and a non-removed portion of the donor substrate that will eventually form a surface layer Forming steps;
(E) heat treating the structure at a temperature near or above the viscous temperature.

In addition, the method of forming the relaxation or pseudo relaxation layer on the substrate has the following characteristics:
-Step (b) and step (c) are not controllable before at least one of the strained layer materials is substantially diffused, before the stressed layer is contaminated, and the surface of the stressed layer Run before becoming so reactive;
Applying a controlled treatment after step (d) to convert at least a portion of the surface layer from a second viscous temperature to a viscous material, thereby forming a second vitreous layer;
Step (e) is carried out during or subsequent to the formation of the second glassy layer;
-Step (e) is followed by a step for removing the second vitreous layer;
The method further comprises a final crystal growth step applied over the structure of the material selected from the semiconductor materials;
Forming a vitreous layer on the receiving substrate, and the method further comprises, prior to step (c), forming a thin layer on the strained layer that is less than the thickness of the strained layer;
-Step (b) consists of the following two successive operations:
(B1) an operation of growing a semiconductive layer on the strained layer;
(B2) performing a controlled process for converting at least a portion of the layer formed in step (b1) from a viscous temperature to a viscous material, thereby forming a vitreous layer;
-Before step (c), forming a bonding layer on the receiving substrate;
The bonding layer is SiO ₂ ;
The material removal of step (d) is substantially achieved by separation by supplying energy at a depth close to the thickness of the surface layer in the embrittled area in the donor substrate;
-Prior to step (c), forming an embrittled area by implanting atomic species into the donor substrate;
-Before step (a), forming a donor substrate, which comprises the following operations:
The operation of forming a perforated layer on the crystalline support substrate,
Including the operation of growing a crystal layer on the perforated layer;
The whole [support substrate / porous layer / crystal layer] hits the donor substrate, and the porous layer corresponds to an embrittled area in the donor substrate.
The material removal of step (d) comprises a selective chemical etching;
-The glassy layer formed in step (b) is electrically insulated;
The glassy layer formed in step (b) is SiO ₂ ;
The donor substrate is Si and the strained layer is Si _1-x Ge _x ;
The donor substrate comprises a Si bulk holding substrate and a buffer structure with a Si lattice parameter adapted to Si _1-x Ge _x , and the strained layer is a Si strained layer and a Si _1-z Ge _z strained layer with z> x And comprising:
The layer grown in step (b1) is Si and the controlled treatment applied in step (b2) converts at least part of the Si of the layer formed in step (b1) into SiO ₂ , resulting in SiO ₂ glass Controlled thermal oxidation treatment to form a porous layer;
The controlled process is a controlled thermal oxidation process that converts at least a portion of the Si in the surface layer into SiO ₂ and consequently forms a _second SiO ₂ glassy layer;
The method further comprises, after step (e), removing the second vitreous layer by a chemical treatment based on hydrofluoric acid;
-Step (e) comprises a heat treatment;
The material used for growth on the structure after removal of the second vitreous layer is Si;
The vitreous layer formed in step (b) is electrically insulated, and the structure formed is a semiconductor-on-insulator structure whose semiconductive thickness was relaxed or pseudo-relaxed in step (e) Comprising a strained layer;
The method further comprises at least one of: preparing for component manufacture; and manufacturing the component in a strained layer, optionally in an epitaxially grown layer thereon.

  Other aspects, objects, and advantages of the present invention will become more apparent upon reading the following description of preferred method applications of the present invention, by way of non-limiting illustration, with reference to the accompanying drawings. Will.

  The first object of the present invention is to form a relaxation or pseudo relaxation useful layer on a substrate.

  The second object of the present invention is to form a useful layer of strained material on a relaxed or pseudo-relaxed useful layer.

  A “useful layer” according to the invention is a layer intended to receive an electronic, optical or optoelectronic component during processing after application of the method according to the invention.

  The third object of the present invention consists in protecting the layer to be relaxed or quasi-relaxed from the atmosphere surrounding the structure enclosing it, beginning with the application of the method according to the present invention and in particular during heat treatment. To prevent one or more atomic species of the material from diffusing.

  A fourth object of the present invention is to allow various surface finishing techniques to be applied to the desired structure without compromising the quality of the layer to be relaxed or pseudo-relaxed during fabrication.

The fourth problem is particularly desirable to use various processing techniques on the structure where the layer to be relaxed or pseudo-relaxed is Si _1-x Ge _x and more usually applied on the Si structure or layer. To achieve in certain cases.

  The method according to the invention comprises the main steps (1), (2) and (3).

  A preferred method according to the present invention will be described with reference to FIGS. 1a-1i.

  A source wafer 10 according to the present invention is shown with reference to FIG.

The wafer 10 consists of a donor substrate 1 and a strained Si _1-x Ge _x layer 2.

  In the first configuration of the donor substrate 1, the latter consists entirely of single crystal Si with the first lattice parameter. Advantageously, here the donor substrate 1 is produced by Czochralski growth.

  In the second configuration of the donor substrate 1, the latter presents an upper Si layer (not shown in FIG. 1) that exhibits an interface with the strained layer 2 and has a first lattice parameter at the interface with the strained layer 2. It is a pseudo substrate provided.

  Advantageously, since the first layer parameter of the upper layer is the nominal lattice parameter of Si, the latter is in a relaxed state.

  Since the upper layer has a sufficiently large thickness, the lattice parameter can be imposed on the strain layer 2 covering the upper layer, and the latter does not greatly affect the crystal structure of the upper layer of the donor substrate 1.

  Whatever the configuration of the donor substrate 1 to be selected, the latter has a crystal structure with a low density of structural defects such as dislocations.

The strained layer 2 preferably consists only of a single Si _1-x Ge _x thickness.

  The Ge concentration in the strained layer 2 is preferably greater than 10%, ie an x value greater than 0.10.

  Since the lattice parameter of Ge is about 4.2% greater than that of Si, the material chosen to form such a strained layer 2 has a second nominal lattice parameter that is significantly greater than the first lattice parameter.

  The formed strained layer 2 is then elastically distorted by compression by the donor substrate 1, i.e. the strained layer 2 has a lattice parameter which is much less than the second lattice parameter of its constituent material due to the strain, so that the first It has a lattice parameter close to the lattice parameter.

  Preferably, the strained layer 2 further has a substantially constant atomic composition.

  Advantageously, the strained layer 2 is formed by crystal growth, such as epitaxy, using known techniques such as LPD, CVD and MBE (abbreviation for liquid phase deposition, chemical vapor deposition and molecular beam epitaxy respectively) techniques. It is formed on the donor substrate 1.

  For example, in order to obtain such a strained layer 2 without extremely many crystallographic defects such as point defects or extended defects such as dislocations, the donor substrate 1 and the strained layer (the holding substrate 1 and It is advantageous to select a crystalline material that forms the vicinity of the interface) with a sufficiently small difference between the respective first and second nominal lattice parameters.

  For example, such a lattice parameter difference is typically between about 0.5% and about 1.5%, but may be larger.

For example, Si _1-x Ge _x with x = 0.3 has a nominal lattice parameter about 1.15% greater than Si.

  On the other hand, if the thickness of the strained layer 2 is substantially constant, a substantially constant intrinsic property can be obtained, or it can facilitate bonding with the receiving substrate 5 (shown in FIG. 1), or both. Is preferred.

  In order to prevent relaxation of the strained layer 2 or to prevent the appearance of plastic type internal defects, the latter thickness should further be below the critical thickness of the elastic strain.

  The critical elastic strain thickness mainly depends on the material chosen for the strained layer 2 and the lattice parameter difference between the donor substrate.

  However, it also depends on the growth parameters such as the temperature at which it is formed, the nucleation site where the epitaxy was performed, or the growth technique used (eg, CVD or MBE).

The critical thickness value of the Si _1-x Ge _x layer is described by Friedrich Schaffler, “High-mobility Si and Ge structures” (“Semiconductor Science Technology” 12 [1997] 1515-1549). Please refer to.

  For other materials, those skilled in the art will be able to refer to today's techniques in determining the value of the critical elastic thickness of the material chosen for the strained layer 2 formed on the donor substrate 1.

Thus, Si _1-x Ge _x , where _x is between 0.10 and 0.30, is typically between 200 Å and 2000 、, preferably between 200 Å and 500 特 に, especially by adapting the growth parameters. Thickness.

  Therefore, the formed strained layer 2 has a lattice parameter substantially close to that of the growth substrate 1 and exhibits an internal elastic strain in compression.

  Referring to FIG. 1 c, the vitreous layer 4 is formed on the strained layer 2 according to the first embodiment of the vitreous layer 4.

The material constituting the vitreous layer 4 is assumed to be viscous from the viscosity temperature _TG .

Advantageously, the material of the vitreous layer 4 is one of the following materials: BPSG, SiO ₂ , SiON.

When forming a glass layer 4 of SiO _x N _y , the value of y may be advantageously changed in order to change the viscosity temperature _TG which is substantially correlated with the nitrogen composition of such material.

Thus, with the growth composition thereon, the _{T G} of the vitreous layer 4, typically (may vary at 1150 ° C. before and after) _T G of its degree of SiO ₂ and its order of the _Si 3 _{N 4} It becomes possible to change between T _G (higher than 1500 ° C.).

As a result, a large _TG range could be covered by changing y.

If the _TG value of the vitreous layer 4 basically depends on the material of the vitreous layer, it may vary depending on the conditions under which it is formed.

In one advantageous development, the conditions for forming the vitreous layer 4 may be controllably adapted to select “optionally” _TG .

  Therefore, deposition parameters such as temperature, duration, applied amount, potential of gas atmosphere may be changed.

As a result, a doping element may be added to the main gas element contained in the vitrified atmosphere, such as boron or phosphorus, which may have the property of reducing _TG .

The strain layer 2 is:
Before the germanium contained in the strained layer 2 can diffuse into the atmosphere; and before the strained layer 2 becomes significantly contaminated; and before the surface of the strained layer 2 becomes uncontrollably reactive;
Covering with the vitreous layer 4 is important, and it is particularly important when the whole is subjected to heat treatment at a high temperature such as RTA type annealing treatment or sacrificial oxidation treatment.

In a preferred embodiment of the vitreous layer 4, the following steps are applied to the strained layer 2:
(B1) Referring to FIG. 1b, growing a semiconductor material layer 3 on the strained layer 2; then (b2) referring to FIG. 1c, at least a part of the layer formed in step (b1) is A controlled process of converting to a material bearing a result of which the vitreous layer 4 is formed.

  Advantageously, the material chosen for layer 3 is Si so as not to change the strain of strained layer 2.

  The thickness of the formed layer 3 is typically between about 5 and about 5000 and more specifically between about 100 and about 1000.

For the same reasons as explained above, the crystal growth of layer 3 in step (b1) is preferably prior to the Ge diffusion, ie:
Immediately after the formation of the strained layer 2 if the temperature for forming the strained layer 2 is maintained; or immediately after the temperature rise following the temperature drop to room temperature that occurs immediately after the formation of the strained layer 2 Apply.

  The preferred method for growing layer 3 is in-situ growth following the growth of strained layer 2.

  The growth technique used in step (b1) may be a technique such as epitaxy, LPD, CVD, or MBE.

  The vitreous layer 4 may be produced by heat treatment under an atmosphere having a predetermined composition.

Therefore, in order to convert the Si layer 3 into the SiO ₂ vitreous layer 4, the controlled thermal oxidation treatment may be performed on the Si layer 3 in step (b2).

  During the latter step, the oxidation parameters (temperature, duration, oxygen concentration) are used to control the thickness of the oxide formed and to stop the oxidation near the interface between layers 2 and 3. It is important to accurately apply other gases in the oxidizing atmosphere.

  For such thermal oxidation, preferably dry oxygen or steam atmosphere may be used at a pressure of 1 atm or higher.

  In this case, preferably, the duration of the oxidation may be changed in order to control the oxidation of the surface layer 3.

  However, such control may be achieved by changing one or more other parameters in combination with the time parameter or separately from the time parameter.

For this embodiment of such a SiO ₂ vitreous layer 4 on a SiGe layer, reference is made in particular to patent document US6352942.

  According to the second embodiment of the vitreous layer 4 and as an alternative to the two steps (b1) and (b2) referred to by FIGS. 1b and 1c respectively, the atoms are deposited by a method of depositing atomic species on the strained layer 2 Apply seed deposition.

  In the first case, atomic species composed of viscous material will be deposited directly.

Thus, for example, SiO ₂ molecules may be deposited to form the SiO ₂ glassy layer 4.

In the second case, the following operation may be performed.
Deposition of amorphous Si atomic species to form an amorphous Si layer; and thermal oxidation of such amorphous Si layer, thereby forming a SiO ₂ glassy layer 4.

  Whichever case of such deposition is selected, atomic species deposition should be performed prior to Ge diffusion, prior to strain layer 2 contamination and uncontrolled surface reactivation, during which strain layer 2 This should be even more so if it is kept at high temperatures.

  With reference to FIGS. 1d, 1e and 1f, the steps of taking the strained layer 2 and the vitreous layer 4 from the donor substrate 1 for transfer onto the receiving substrate 7 are shown.

For this purpose, the method according to the invention applies a technique consisting of two successive main steps:
-Joining of the receiving substrate 7 and the vitreous layer 4;
-Removal of part of the donor substrate 1;

  Referring to FIG. 1i, the bonding is performed.

  Prior to bonding, an optional step of forming a bonding layer on at least one of the two surfaces to be bonded may be performed, and such bonding layer has bonding properties at or above room temperature.

Thus, for example, when the other surface to be bonded is SiO ₂ or Si, the bonding quality can be improved by forming the SiO ₂ layer.

In this case, such a SiO ₂ bonding layer is advantageously produced by depositing SiO ₂ atomic species or by thermal oxidation of the surfaces to be bonded if the latter surface is Si.

  In order to make the surfaces to be joined as smooth and clean as possible, the step of preparing the surfaces to be joined is advantageously applied prior to joining.

  Chemical treatment suitable for cleaning the surfaces to be joined, such as weak chemical etching, RCA treatment, ozonization tank, and water washing, may be performed.

  Mechanical or mechanical chemical treatment such as polishing, grinding, CMP (Chemical Mechanical Planarization Method), atomic species bombardment, or the like may be performed.

  Such a joining operation is performed by bringing the surfaces to be joined into contact with each other.

  The bond is preferably of a molecular nature that utilizes the hydrophilicity of the surfaces to be bonded.

  In order to impart or strengthen the hydrophilicity of the surfaces to be joined, pre-soaking of both structures to be joined in a bath may be performed, for example, washing with deionized water.

  By strengthening the joint bond, the entire joined joint may be further annealed, for example, by changing the nature of the joint bond, such as a covalent bond or other bonds.

Therefore, if the vitreous layer is SiO ₂ and the SiO ₂ bonding layer is formed in advance prior to bonding to the receiving substrate 7, the bonding can be strengthened by annealing.

  For more information on bonding technology, see the document "Semiconductor Wafer Bonding" (Science and technology, Interscience Technology) by Q.Y.Tong, U.Gosele and Wiley.

  After bonding the whole, the material removal suitable according to the present invention is applied, which involves pulling apart a portion of the donor substrate 1 by supplying energy at the embrittled area 6 in the donor substrate 1.

  Referring to FIGS. 1d and 1e, such an embrittlement area 6 is an area that is generally parallel to the bonding surface and exhibits bond brittleness between the lower portion 1a of the donor substrate 1 and the upper portion 1b of the donor substrate 1, and thus This weak bond may be broken when energy such as thermal energy or mechanical energy is supplied.

According to a first embodiment of the embrittlement area 6, a technique called smart cut ^(R) is applied, which first involves the implantation of atomic species into the donor substrate 1 in the embrittlement area 6.

  The species to be injected can be hydrogen, helium, a mixture of both, or other lightweight species.

  The implantation is preferably performed immediately before joining.

  In selecting the implantation energy, the seed implanted through the surface of the vitreous layer 4 traverses the thickness of the vitreous layer 4, the thickness of the strained layer 2, and the predetermined thickness of the upper portion 1b of the receiving substrate 1. Select as follows.

  The implantation into the donor substrate 1 is preferably made sufficiently deep so that the strained layer 2 is not damaged during the separation step from the donor substrate.

  Thus, the implantation depth in the donor substrate is typically about 1000 mm.

The brittleness of the bond in the embrittled area 6 is obtained mainly by the choice of dosage, which is typically between 10 ¹⁶ cm ⁻² and 10 ¹⁷ cm ⁻² , more specifically about 2. Between 10 ¹⁶ cm ⁻² and 7.10 ¹⁶ cm ⁻² .

  At that time, the separation in the embrittled area 6 is usually performed by supplying at least one of mechanical energy and thermal energy.

For more information on the Smart Cut ^(R), the article by J.-P.Colinge, "Silicon-On -Insulator Technology: Materials to VLSI ( Silicon - On - Insulator: Materials ^{VLSI), 2 nd edition",} Kluwer Academic Publishers Ed., Pages 50 and 51.

  According to the second embodiment of the embrittlement area 6, the technique described in patent document EP0849788 is applied.

  Here, the embrittlement layer 6 is produced before the strained layer 2 is formed and during the formation of the donor substrate 1.

Fabrication of the embrittlement layer includes the following main operations:
-Formation of a porous layer on the Si holding substrate 1A;
-Growth of Si layer 1B on the porous layer.

  At that time, the whole / holding substrate 1 </ b> A / porous layer / Si layer 1 </ b> B / forms the donor substrate 1, and the porous layer forms the embrittled area 6 of the donor substrate 1.

  Supplying energy in the perforated embrittlement area 6 such as supplying at least one of heat and mechanical energy leads to separation of the holding substrate 1A from the layer 1B.

  Thus, the preferred technique according to the present invention for removing material in the embrittled area 6 achieved according to one of the two non-limiting embodiments described above, is to quickly take most of the donor substrate 1 as one mass. Allows to be removed.

  It also offers the possibility to reuse the removed part 1A of the donor substrate 1 in another way, for example in the method according to the invention.

  On the removed portion 1A and on another optional portion of at least one of the donor substrate and the other layer, re-formation of the strained layer 2 is preferably performed after polishing the surface of the removed portion. Also good.

  Referring to FIG. 1f, after the remaining portion 1B is separated from the removed portion 1A of the donor substrate 1, the finishing material is removed so that the remaining portion 1B can be removed.

  In order to remove the portion 1B and complete the lamination (strengthening the bonding interface, removing the bump, hardening the defect, etc.), polishing, grinding, CMP planarization method, RTA thermal annealing, sacrificial oxidation, chemical etching, etc. Finishing techniques may be applied alone or in combination.

  Advantageously, at least at the end of the step, selective chemical etching is applied in combination with mechanical means or alone, with the removal of the finishing material.

Therefore, a solution mainly containing KOH, NH ₄ OH (ammonium hydroxide), TMAH, EDP, or HNO ₃ , or HNO ₃ , HNO ₂ , H ₂ O ₂ , HF, H ₂ SO ₄ , H ₂ SO _2. , _CH 3 _COOH, H 2 _{O 2,} and the solution currently under study for mixing substances such as _{H 2} O (described patent document WO99 / 53539,9 page), to strained _{Si 1-x} Ge _x layer 2 May be advantageously used to selectively etch the Si portion 1B.

  After the bonding step, further material removal techniques according to the present invention without separation and without embrittlement areas may be applied to remove parts of the donor substrate 1.

  It performs at least one of chemical etching and mechanical etching.

  For example, any selective etching may be performed on the material to be removed from the donor substrate 1 by an etch-back type method.

  In such a technique, the donor substrate 1 is etched from behind, that is, from the empty surface of the donor substrate 1.

  Wet etching may be performed by applying an etching solution suitable for the material to be removed.

  Dry etching may be applied to remove material such as plasma or spray etching.

  Etching (one or more times) may be further limited to chemical, electrochemical, or photochemical.

  Before or after etching (one or more times), the donor substrate may be mechanically ground, such as by grinding, polishing, mechanical etching, or atom species spraying.

  The etching (one or more times) may be accompanied by mechanical grinding such as polishing in which the action of a mechanical abrasive in the CMP method is arbitrarily combined.

  Any of the above-described techniques for removing material from the donor substrate 1 have been presented here as examples, but they are in no way limiting, and the present invention is based on the method according to the invention from the material from the donor substrate 1. Spans all kinds of technologies that can eliminate.

  Referring to FIG. 1f, the portion 1B of the donor substrate 1 is stored after removal.

  This has an effect of leaving the strained layer 2 in an embedded state, and thus has an effect of protecting it from the external atmosphere, and achieves the first problem defined in the application of the present method below.

  Whatever the material removal technique selected from the techniques already described or other known techniques, optionally selective chemical etching, CMP polishing, heat treatment, bombardment using atomic species, or some other smoothing technique, etc. A surface finishing step for the remaining part 1B of the donor substrate 1 is advantageously applied.

Therefore, after performing Smart Cut ^(R) type material removal step, such as the one of the following processes, preferably using a smoothing technique:
Polishing to obtain a thickness of about 200 mm to about 800 mm;
Ar / H ₂ RTA high speed annealing followed by polishing to obtain a thickness of about 200 to about 800 mm;
・ One fast RTA annealing;
Ar / H ₂ oven annealing.

  Those finishing treatments applied to the Si surface (of the remaining part 1B of the donor substrate 1) are carried out in particular within the framework of the invention.

  Actually, since these technologies are not yet perfect for SiGe, when the SiGe strained layer 2 is exposed, it is difficult to apply these technologies without deteriorating the strained layer 2. Will.

  By having the Si surface layer 1B, the surface of the structure obtained after separation can be smoothed efficiently.

  Referring to FIG. 1f, after material removal, a structure comprising a receiving substrate 7, a vitreous layer 4, a strained layer 2, and a Si surface layer 1B (corresponding to the remaining part of the donor substrate 1) is obtained. .

  Therefore, the strained layer 2 is substantially protected from the outside by the surface layer 1B covering the top and the glass layer 4 lying below.

  According to an alternative method, the surface layer 1B is stored as is.

  However, with reference to FIG. 1g, the formation of the second vitreous layer 8 made of a material that is viscous from the second viscosity temperature is advantageously applied at the surface of the structure, resulting in this.

The material chosen for the second vitreous layer 8 may be, for example, one of the following materials: SiO ₂ , BPSG, SiO _x N _y .

  The second vitreous layer 8 is formed by converting the surface layer 1B into the vitreous layer 4, preferably by a suitable controlled process.

  Therefore, the second vitreous layer 8 may be produced by heat treatment under an atmosphere having a predetermined composition.

Therefore, in order to convert the Si surface layer 8 into the SiO ₂ glassy layer 8, the Si surface layer 8 may be subjected to controlled thermal oxidation treatment.

  During the latter step, the oxidation parameters (temperature, duration, oxygen concentration, oxidation) are used to control the thickness of the oxide formed and to stop the oxidation near the interface between layers 2 and 1B. It is important to accurately apply other gases in the atmosphere.

  For such thermal oxidation, preferably dry oxygen or steam atmosphere will be used at temperatures between about 500 ° C. and about 1050 ° C. at a pressure of 1 atm or higher.

  In so doing, the duration of the oxidation will be altered, preferably to control the oxidation of the surface layer 8.

  However, such control may be achieved by changing one or more other parameters in combination with the time parameter or separately from the time parameter.

  Referring always to FIG. 1g, a heat treatment at a temperature close to or above the viscous temperature is then applied.

  The main purpose of such heat treatment is to relieve strain in the strained layer 2.

In fact, a heat treatment at or near the viscosity temperature _TG of the glassy layer 4 will cause the viscosity of the latter layer, which causes the strained layer to relax at its interface with the glassy layer 4. Would allow decompression of at least a portion of its internal distortion.

Thus, if the vitreous layer 4 is SiO ₂ formed by thermal oxidation, the strain layer 2 can be relaxed or simulated by a heat treatment at least about 1050 ° C., preferably at least about 1200 ° C., which lasts for a predetermined period. Relaxation will occur.

  The heat treatment typically lasts between a few seconds and a few hours.

  Unlike today's technology, such relaxation of the strained layer 2 is achieved without bringing the strained layer 2 into contact with the outside world, in particular by preventing the diffusion of Ge.

  Therefore, the strained layer 2 becomes the relaxation layer 2 '.

  In addition to the relaxation of the strained layer 2, another heat treatment effect on the structure may be obtained.

  The second purpose of the heat treatment may be to achieve annealing that strengthens the bonding between the receiving substrate 7 and the vitreous layer 4.

  In fact, since the temperature selected for the heat treatment is higher than or around the viscosity temperature of the vitreous layer 4, a particularly stronger adhesive bond with the receiving substrate 7 occurs from the temporarily viscous latter. There is also.

Thus, the example of joining the SiO ₂ vitreous layer 4 to the receiving substrate on which the SiO ₂ bonding layer is applied will be drawn again, and a particularly strong covalent bond will be generated from the viscosity of both contact layers.

The third purpose is to perform the above heat treatment in order to form the second SiO ₂ glassy layer 8 by thermal oxidation.

  In fact, such a vitreous layer 8 is formed by simultaneously injecting oxygen into the oven during or following the same heat treatment different from the heat treatment that relaxes the strained layer 2, or some heat treatment Form after the heat treatment of or during the heat cycle.

Finally, a structure 20 consisting of the whole / glassy layer 8 / relaxed Si _1-x Ge _x 2 ′ / glassy layer 4 / receiving substrate 7 / is obtained.

Thereby, the relaxed Si _1-x Ge _x of the layer 2 ′ is protected from the outside by both adjacent glassy layers 4 and 8.

In that case, it is sufficient to remove the vitreous layer 8 by, for example, a suitable chemical treatment in order to expose the relaxed Si _1-x Ge _x layer 2 ′.

Thus, if the vitreous layer 8 is SiO ₂ , the structure 20 could be advantageously treated with hydrofluoric acid HF to remove SiO ₂ from the vitreous layer 8.

Referring to FIG. 1h, a structure 30 consisting of / relaxed Si _1-x Ge _x 2 ′ / glassy layer 4 / receiving substrate 7 is finally obtained.

Such a structure 30 is an SGOI structure (silicon germanium on insulator) when the vitreous layer 4 is electrically insulated, for example, the SiO ₂ vitreous layer 4 or the like.

In that case, the relaxed Si _1-x Ge _x layer 2 ′ having such a structure has a surface whose surface roughness is compatible with the growth of another crystalline material.

In order to improve the surface properties, a minor surface treatment such as polishing suitable for Si _1-x Ge _x may be optionally applied.

Referring to FIG. 1i, in an optional step of the present invention, a grown Si layer on the relaxed Si _1-x Ge _x layer 2 ′ is applied with a thickness that is well below the strain critical thickness of the material comprising it, Therefore, distortion is caused by the relaxed Si _1-x Ge _x layer 2 ′.

Finally, a structure consisting of strained Si / relaxed Si _1-x Ge _x 2 ′ / glassy layer 4 / receiving substrate 7 is then obtained.

Such a structure 40 is a Si / SGOI structure when the vitreous layer 4 is electrically insulated, for example, when it is the SiO ₂ vitreous layer 4 or the like.

  With reference to Figures 2a-2i, 3a-3i, and 4a-4i, an alternative to such a method is presented.

  With reference to FIGS. 2a-2i, and more specifically with reference to FIG. 2g, such a method is described with reference to FIGS. 1a-1i, except for converting the surface layer 1B to a second vitreous layer 8. This step is generally performed so that the entire surface layer 1B is not converted.

  Therefore, the portion of the Si surface layer 1B inserted between the second vitreous layer 8 and the strained layer 2 remains there, and the intermediate layer 9 is formed.

  Referring to FIG. 2 h, the intermediate layer 9 is preserved after the heat treatment for relaxing the strained layer 2.

  Since the intermediate layer 9 is advantageously stored with a thickness less than the strain critical thickness, it will later be distorted by the relaxation layer 2 '.

  Referring to FIG. 2 i, the Si layer growth may be resumed on the intermediate layer 9 to form a strained Si layer 11 that is substantially the same as that of FIG. 2 i.

  In order to improve the quality of the crystal growth to be applied, a smoothing step for the growth surface by one of the techniques already described herein may be pre-applied to the silicon growth.

  In particular developments, where the heat treatment to relieve strain in the strained layer 2 is performed at a temperature and duration higher than the standard temperature and longer than the standard duration, respectively, where Ge diffusion into Si begins, the strained layer Ge contained in 2 may diffuse into the intermediate layer 9.

  Therefore, relaxation of the strained SiGe layer 2 is preferably performed before the epitaxy of the strained Si layer 11 is resumed.

  However, in certain other cases, it may be desired if this diffusion effect is properly controlled.

Thus, the diffusion may be controlled to form a unique Si _1-x Ge _x layer in which the Ge species are uniformly dispersed throughout both layers 2 and 9 and the Ge concentration is generally uniform.

  A description of the latter can be found especially in patent document US5461243, third tier, lines 48-58.

  Referring to FIGS. 3a-3i, and more specifically to FIG. 3c, such a method is generally the same as that described with reference to FIGS. 1a-1i, except for the step of converting layer 3 to vitreous layer 4. The same is applied here, so that the entire layer 3 is not converted.

  Therefore, the portion of the Si layer 3 inserted between the vitreous layer 4 and the strained layer 2 remains there, and the insertion layer 5 is formed.

  The insertion layer 5 is prepared to have a typical thickness of around 10 nm, which is in any case much less than that of the strained layer 2.

  During the heat treatment to relieve the strain of the strained layer 2, the latter will try to reduce its internal elastic strain energy by utilizing the viscosity of the viscous glassy layer 4, and the insertion layer 5 Since it has a relatively small thickness relative to the overlying strained layer 2, the strained layer 2 will impose its relaxation requirements on the insertion layer 5.

  As a result, the strain layer 2 forces the insertion layer 5 to undergo strain at least in part.

  At that time, the strained layer 2 becomes at least partially a relaxation layer 2 ′.

  At that time, the relaxation insertion layer 5 becomes the strain insertion layer 8 '.

  A description of the latter can be found in particular in patent document US5461243, third tier, lines 28 to 42.

  Referring to FIG. 3 h, such a strain insertion layer 5 ′ is stored after the heat treatment for relaxing the strain layer 2.

The structure formed at that time is a structure consisting of relaxed Si _1-x Ge _x / strained Si vitreous layer 4 / receiving substrate 7 /.

Such a structure 30 is an SG / SOI structure when the vitreous layer 4 is electrically insulated, for example, when it is the SiO ₂ vitreous layer 4 or the like.

In this case, a selective chemistry based on, for example, HF: H ₂ O ₂ : CH ₃ COOH (selectivity approximately 1: 1000) is obtained in order to finally obtain a structure consisting of / strained Si / glassy layer 4 / receiving substrate 7 / It is possible to arbitrarily remove the relaxed Si _1-x Ge _x layer 2 ′ by etching.

Such a structure is a strained SOI structure when the glassy layer 4 is electrically insulated, for example, when it is the SiO ₂ glassy layer 4 or the like.

  Instead of performing this chemical etching, referring to FIG. 3i, it is possible to resume the Si layer growth on the relaxation layer 2 ', and form a strained Si layer 11 substantially the same as that of FIG. 3i.

The structure formed at that time is a structure 40 consisting of strained Si / relaxed Si _1-x Ge _x / strained Si / glassy layer 4 / receiving substrate 7 /.

Such a structure 40 is a Si / SG / SOI structure when the vitreous layer 4 is electrically insulated, for example, when it is the SiO ₂ vitreous layer 4 or the like.

  In particular developments, where the heat treatment to relieve strain in the strained layer 2 is performed at a temperature and duration higher than the standard temperature and longer than the standard duration, respectively, where Ge diffusion into Si begins, the strained layer 2 may diffuse into the strain insertion layer 5 ′.

  Therefore, relaxation of the strained SiGe layer 2 is preferably performed before the epitaxy of the strained Si layer 11 is resumed.

  However, in certain other cases, it may be desired if such a diffusion effect is appropriately controlled.

Thus, the diffusion may be controlled to form a unique Si _1-x Ge _x layer in which the Ge species are uniformly dispersed throughout both layers 2 and 5 and the Ge concentration is generally uniform.

  A description of the latter can be found in particular in patent document US461243, third tier, lines 48-58.

Referring to FIGS. 4a to 4i, and more specifically FIGS. 4c and 4g, such a method is generally the same as that described with reference to FIGS. 1a-1i, with the exception of:
The step of converting layer 3 to vitreous layer 4 is different, here the same step is applied so that the entire layer 3 is not converted;
The step of converting the surface layer 1B into the second vitreous layer 8 is different, and here the same step is applied so that the surface layer 1B is not converted.

  In fact, this method forms the insertion layer 5 (see FIG. 3c), the same steps as described with reference to FIG. 3c, and the intermediate layer 9 (see FIG. 2g), see FIG. 2g. The same steps as described above.

  Thus, the means of forming both layers 5 and 9 and the possibility of their development and their effect on the final structure are in the manner described with reference to FIGS. 2a-2i and 3a-3i. It is almost the same as the thing.

Referring to FIGS. 5a-5h, and more specifically FIGS. 5b and 5d, the method is generally the same as that described with reference to FIGS. 1a-1i, with the exception of:
-Referring to step 5b, the epitaxially grown Si layer 3 on the strained layer 2 is a very thin layer, the thickness of which is typically 100 to 300 mm, well below that of the strained layer 2;
-Referring to Figure 5d, the vitreous layer 4 is formed on the receiving substrate 7.

Thus, the Si layer 3 would be able to:
Protecting the overlying SiGe strained layer 2 from Ge diffusion, extraneous contamination and uncontrolled reactivation of its surface;
The application of a fully-developed surface finishing means to Si, as opposed to a surface finishing means for SiGe which is not fully mastered, and their finishing techniques (as already described herein) With good bonding with.

  Referring to FIG. 5 d, prior to bonding, the vitreous layer 4 is formed on the receiving substrate 7 according to the first embodiment of the vitreous layer 4.

The material forming the vitreous layer 4 is assumed to be viscous from the viscosity temperature _TG .

Advantageously, the material of the vitreous layer 4 is one of the following materials: BPSG, SiO ₂ , SiON.

  This first embodiment of forming the vitreous layer 4 on the receiving substrate is the first embodiment of forming the vitreous layer 4 on the strained layer 2 described herein above (see FIG. 1c). Apply as well.

Thus, for example, the SiO ₂ glassy layer 4 is formed from oxidation of the Si surface of the receiving substrate 7.

  The formation of the vitreous layer 4 and the bonding of the vitreous layer 4 and the strained layer 2 should be carried out before the diffusion of Ge, before the contamination of the surface of the strained layer 2 and uncontrolled reactivation, If the high temperature is maintained in the strained layer 2 in the meantime, it should be so.

  According to the second embodiment of the glassy layer 4 on the receiving substrate, atomic species are deposited on the receiving substrate 7 by means of depositing atomic species.

In the first case, atomic species composed of glassy materials such as SiO ₂ will be deposited directly.

In the second case, the following operations may be performed:
Deposition of amorphous Si atomic species to form an amorphous Si layer; then thermal oxidation of the amorphous Si layer, thereby forming a SiO ₂ vitreous layer 4.

  Whichever case of such deposition is selected, the deposition of the atomic species should be carried out before the diffusion of Ge, before the contamination of the surface of the strained layer 2 and uncontrolled reactivation, during which the strained layer 2 If the high temperature is maintained, this should be the case.

  Referring to FIGS. 5e, 5f, 5g, and 5h, the same conditions and configurations as described with reference to FIGS. 3f, 3f, 3h, and 3i can be seen, thereby providing a reference layer in the method. 5 becomes the reference layer 3.

Specifically, during heat treatment for relaxation:
The strained layer 2 then becomes at least partly the relaxation layer 2;
The insertion layer 3 then becomes a strained insertion layer 3 ′.

Referring to FIG. 5g, the structure formed in this case is a structure consisting of / relaxed Si _1-x Ge _x / strained Si / glassy layer 4 / receiving substrate 7 /.

Such a structure 30 is an SG / SOI structure when the vitreous layer 4 is electrically insulated, for example, when it is the SiO ₂ vitreous layer 4 or the like.

In this case, a selective chemistry based on, for example, HF: H ₂ O ₂ : CH ₃ COOH (selectivity approximately 1: 1000) is obtained in order to finally obtain a structure consisting of / strained Si / glassy layer 4 / receiving substrate 7 / The relaxed Si _1-x Ge _x layer 2 ′ may be optionally removed by etching.

Such a structure is a strained SOI structure when the glassy layer 4 is electrically insulated, for example, when it is the SiO ₂ glassy layer 4 or the like.

  Instead of performing such chemical etching, referring to FIG. 5h, it is possible to resume the Si layer growth on the relaxation layer 2 ', and form a strained Si layer 11 substantially the same as that of FIG. 5h.

The structure formed at that time is a structure 40 consisting of strained Si / relaxed Si _1-x Ge _x / strained Si / glassy layer 4 / receiving substrate 7 /.

Such a structure 40 is a Si / SG / SOI structure when the vitreous layer 4 is electrically insulated, for example, when it is the SiO ₂ vitreous layer 4 or the like.

  In particular developments, where the heat treatment to relieve strain in the strained layer 2 is performed at a temperature and duration higher than the standard temperature and longer than the standard duration, respectively, where Ge diffusion into Si begins, the strained layer 2 may diffuse into the strain insertion layer 3 ′.

  Therefore, relaxation of the strained SiGe layer 2 is preferably performed before the epitaxy of the strained Si layer 11 is resumed.

  However, in certain other cases, it may be sought if this diffusion effect is appropriately controlled.

Thus, the diffusion may be controlled to form a unique Si _1-x Ge _x layer in which the Ge species are uniformly dispersed throughout both layers 2 and 5 and the Ge concentration is generally uniform.

  An explanation of the latter point can be found especially in patent document US5461243, third stage, lines 48-58.

  With reference to FIGS. 6a-6h, and more specifically with reference to FIG. 6f, the method has been described with reference to FIGS. 5a-5h, except for converting the surface layer 1B to a second vitreous layer 8. In general, the step is applied so that the entire surface layer 1B is not converted.

  Therefore, the portion of the Si surface layer 1B inserted between the second vitreous layer 8 and the strained layer 2 remains there, and the intermediate layer 9 is formed.

  Referring to FIG. 6 g, such an intermediate layer 9 is preserved after the heat treatment to relax the strained layer 2.

  Such an intermediate layer 9 is advantageously stored with a thickness that is less than the strain critical thickness, so that it will later be distorted by the relaxation layer 2 '.

  Referring to FIG. 6h, it is possible to resume the growth of the Si layer on the intermediate layer 9 in order to form a strained Si layer 11 that is substantially the same as that of FIG. 5h.

  In order to improve the quality of the crystal growth to be applied, a smoothing step for the growth surface by one of the techniques already described herein may be pre-applied to the silicon growth.

  In particular developments, where the heat treatment to relieve strain in the strained layer 2 is performed at a temperature and duration higher than the standard temperature and longer than the standard duration, respectively, where Ge diffusion into Si begins, the strained layer 2 may diffuse into the intermediate layer 9 or the insertion layer 3.

  Therefore, relaxation of the strained SiGe layer 2 is preferably performed before the epitaxy of the strained Si layer 11 is resumed.

  However, in certain other cases, such diffusion effects may be sought if appropriately controlled.

Thus, the diffusion may be controlled to form a unique Si _1-x Ge _x layer in which the Ge species are uniformly distributed throughout both layers 2, 3 and 9 and the Ge concentration is generally uniform.

  An explanation of the latter point can be found especially in patent document US5461243, third stage, lines 48-58.

  The steps of making the component may be integrated by any of the above six preferred methods according to the present invention, or the equivalent, or may be followed by the method according to the present invention.

  Thus, the preparatory steps for fabricating the components are described during the method with reference to FIGS. 1g, 2g, 3g, 4g, 5f, or 6f, and in the strained SiGe layer 2 of that structure, FIGS. 3h, 4h, 5g, or 6g and in the SGOI structure relaxed or pseudo relaxed SiGe layer 2 ′ or in reference to FIGS. 1i, 2i, 3i, 4i, 5h, or 6h, the Si / SGOI You may give in the strained Si layer 11 of a structure.

  Preferably, these preparatory steps will be achieved by the vitreous layer 8 always present in the structure, the latter protecting the underlying layer, in particular the strained layer 2 or the relaxation layer 2 ', both of which are SiGe To do.

  For example, a local process for etching a pattern in the layer through the vitreous layer 8 may be performed by lithography, photolithography, reactive ion etching, or other etching techniques involving pattern masking.

  In a specific case, a pattern such as an island is etched into the SiGe strained layer 2 in order to contribute to moderate relaxation of the strained layer 2 when the relaxation heat treatment is performed later.

In the strained Si layer 11 (or in the relaxed SiGe layer 2 ′ if the relaxed SiGe layer 2 ′ is not covered by the strained Si layer 11), in particular, one or more steps for making a component such as a transistor, Preferably, it may be performed at a temperature less than _TG (in order not to change the strain ratio between the relaxing layer 2 ′ and the strained layer 11).

  In a particular method according to the present invention, a component is produced during or subsequent to the heat treatment to relax the strained SiGe layer 2.

  In a particular method according to the present invention, a strained Si layer epitaxy step is applied during or subsequent to the component fabrication step.

  Referring to FIG. 7, which represents the source wafer 10 prior to the formation of the embrittlement zone 6 and the vitreous layer 4, FIGS. 1a to 1i, 2a to 2i, 3a to 3i, 4a to 4i, 5a to 5h, and 6a. 6 to 6h, embodiments of the present invention that differ from the various examples detailed above are presented below, along with the selection of materials comprising the donor substrate 1 and the strained layer 2.

In fact, in contrast to the other examples described above, the donor substrate 1 here comprises a Si holding substrate 1-1, a SiGe buffer layer 1-2, and an upper layer 1 of Si _1-z Ge _z. -3.

  The holding substrate 1-1 preferably has a single crystal bulk structure.

In the buffer layer 1-2, for example, the total composition of Ge in the buffer layer 1-2 is 0% at the interface with the holding substrate 1-2 to the interface with the upper layer 1-3 of Si _1-z Ge _z. It is possible to form a layered structure that develops in stages over Ge100z%.

  In contrast to the buffer layer 1-2, the upper layer 1-3 has a constant Ge composition in its thickness.

  The upper layer 1-3 has a sufficiently important thickness in assigning the lattice parameters to the underlying layer.

Furthermore, the upper layer 1-3 of Si _1-z Ge _z has a relaxed structure.

Thus, the buffer structure (consisting of buffer layer 1-2 and higher layers) enables:
The adaptation of the lattice parameters between the Si holding substrate 1-1 and the nominal lattice parameters of the Si _1-z Ge _z of the upper layer 1-3;
-Crystal defect confinement, in which case there will be no or few defects on the surface of the upper layer 1-3.

  On the donor substrate 1, a strained layer 2 is formed by an epitaxy technique such as a CVD technique (PECVD, MOCVD...).

  First, the strained Si layer 2-1 is formed on the donor substrate 1 with a thickness that is less than the critical thickness at which the strained Si layer 2-1 starts to relax its elastic strain.

Next, a Si _1-x Ge _x strained layer 2-2 is formed on the previous Si strained layer 2-1, and a thickness less than the critical thickness of Si _1-x Ge _x at which relaxation of elastic strain begins is given. .

Information on the critical thickness of each of Si and Si _1-x Ge _x is, for example, “High mobility Si and Ge structures” by Friedrich Schaffler (“Semiconductor science technology” 12 [1997] 1515- 1549).

The x composition of Ge in the Si _1-x Ge _x layer 2-2 is larger than the z composition of Ge in the upper layer 1-3.

Here, the strained layer 2 includes the Si strained layer 2-1 and the Si _1-x Ge _x layer 2-2, and the donor substrate 1 further includes the holding substrate 1-1, the buffer layer 1-2, and the Si _1-z Ge. Given an upper layer 1-3 of _z , a prior example (presented with reference to the preceding figure) of various embodiments for fabricating a semiconductor-on-insulator structure 30 or 40 is shown from the source wafer 10 of FIG. The embrittlement zone 6 is formed in the upper layer 1-3 or the buffer layer 1-2.

After a surface finishing step (e.g. polishing, chemical etching, oxidation, annealing, other finishing means), the semiconductor-on-insulator structure (not shown) obtained at that time comprises a receiving substrate 7, a glassy layer 4, Si _1- The remaining portions of the _x Ge _x strained layer 2-2, the Si strained layer 2-1, and the Si _1-z Ge _z upper layer 1-3 are continuously provided.

  And the heat processing at the temperature close | similar to or exceeding the viscosity temperature of the glassy layer 4 formed previously is processed.

At this time, the Si _1-x Ge _x layer 2-2 is at least partially relaxed by the heat treatment.

At that time, the relaxed Si _1-x Ge _x layer 2-2 imposes an elastic constraint on the uppermost Si strained layer 2-1 and the rest of the upper layer 1-3 of Si _1-z Ge _z .

Elastic constraints in the Si strained layer 2-1 (previously strained by the Si _1-z Ge _z upper layer 1-3) are then increased by the fact that the x composition of Ge is more important than the z composition.

Thus, a semiconductor _- on-insulator structure is obtained in which the lattice parameter at the semiconductor portion is close to or equal to that in the bulk configuration of the Si _1-x Ge _x material.

An optional additional step of removing the remainder of the Si _1-z Ge _z upper layer 1-3 is, for example, HF: H ₂ O ₂ : CH ₃ COOH (selectivity between SiGe and Si of about 1 : 1000) or the like by selective chemical etching using an etchant.

In contrast to the prior art, this semiconductor-on-insulator structure does not derive parameters from a source wafer with a buffer structure that conforms to Si _1-x Ge _x , but rather parameters from Si _1-z Ge _z (z < Obtain from a buffer structure conforming to x).

By the way, the buffer structure that conforms to the lattice parameter of Si _1-x Ge _x is thicker than the buffer structure that conforms to the lattice parameter of Si _1-z Ge _z , and has a larger number of layers, resulting in more production. Takes time and money.

  This method according to an embodiment of the invention provides technical and economic improvements compared to the latter prior art.

  The various techniques described in the present invention are given here by way of example, but are in no way limiting and the invention covers all kinds of techniques to which the method according to the invention can be applied.

  Epitaxy of SiGe or SiGeC layer, strained Si or SiC layer epitaxy, or SiGe or SiGeC layer to form a multi-layer structure, final structure such as alternating epitaxy of strained Si or SiC layer (FIGS. 1h, 1i One or several epitaxies may be applied on the structure 30 or 40) taken up with reference to 2h, 2i, 3h, 3i, 4h, 4i, 5g, 5h, 6g, 6h.

  When the final structure is completed, for example, a finishing process including annealing may be optionally performed.

  The present invention is not limited to the SiGe strained layer 2 but extends to the formation of the strained layer 2 with another type of III-V or II-VI type material or other semiconductor materials.

  In the semiconductor layer described in this specification, other constituent elements such as carbon having a carbon concentration of 50% or less in the corresponding layer, or more specifically, a carbon concentration of 5% or less may be added.

1a-1i show the various steps of the first method according to the invention. Figures 2a-2i show various steps of the second method according to the invention. Figures 3a-3i show the various steps of the third method according to the invention. 4a-4i show the various steps of the fourth method according to the invention. Figures 5a-5i show the various steps of the fifth method according to the invention. 6a-6i show the various steps of the sixth method according to the invention. FIG. 5 shows an example of a source wafer in which a layer to be transitioned is grown on a SiGe buffer structure.

Explanation of symbols

2 'relaxation layer 4 glassy layer 7 receiving substrate 8 surface layer (second glassy layer)
20 Structure

Claims (21)

A method of forming a relaxation or pseudo relaxation layer on a substrate, wherein the relaxation or pseudo relaxation layer (2 ′) is made of a material comprising Si _1-x Ge _x , the method comprising the following steps:
(A) growing an elastically strained layer (2) of Si _1-x Ge _x on the donor substrate (1);
(B) forming a vitreous layer (4) on the strained layer (2) or on the receiving substrate (7), which is viscous from the viscous temperature and made of a material comprising BPSG, SiO ₂ or SiON Step to do;
(C) bonding the receiving substrate (7) to the strained layer (2) via the vitreous layer (4);
(D) removing a portion of the donor substrate (1), the receiving substrate (7), the vitreous layer (4), the strained layer (2), and consequently the surface layer ( Forming a structure comprising an unremoved portion of said donor substrate (1) that will form 1B);
Treating the structure to convert at least a portion of the surface layer (1B) from a second viscous temperature to viscous SiO ₂ to form a second vitreous layer (8);
(E) heat-treating the structure at a temperature above the viscosity temperature of the vitreous layer (4) to cause the viscosity of the vitreous layer (4) and the relaxation of the elastic strained layer (2); Or obtaining a pseudo relaxation layer,
Steps (b) and (c) are performed before exposure of the strained layer (2) to prevent Ge from diffusing into the atmosphere from the strained layer (2),
Step (e) is performed continuously during or after the formation of the second glassy layer (8).   The method of claim 1, further comprising the step of removing the second vitreous layer (8) after step (e).   3. The method according to claim 2, further comprising a final step of growing Si crystals on the relaxed or pseudo relaxed layer (2 ') of a material selected from semiconductor materials.   Forming the vitreous layer (4) on the receiving substrate (7), and before the method before step (c), forming a thin layer with a thickness less than the thickness of the strained layer (2) 4. The method according to claim 1, further comprising the step of forming on the strained layer (2). Step (b) consists of two successive operations:
(B1) an operation of growing a semiconductor material layer on the strained layer;
(B2) including an operation of converting at least a part of the layer formed in step (b1) from viscous temperature to viscous SiO ₂ and, as a result, performing a controlled process for forming the glassy layer. The method according to any one of claims 1 to 4, wherein:   6. The heat treatment of step (e) is applied to strengthen the bond between the receiving substrate (7) and the vitreous layer, according to any one of claims 1-5. Method. Wherein further comprising the step of forming a bonding layer made of SiO ₂ on a receiving substrate (7) The method of claim 6. The material removal in step (d) is achieved by separation by supplying energy at a depth close to the thickness of the surface layer (1B) in the embrittled area in the donor substrate (1). A method according to any one of claims 1 to 7.   The method according to claim 8, further comprising the step of forming the embrittled area by implanting atomic species into the donor substrate (1) prior to step (c). Prior to step (a), the method further comprises the step of forming a donor substrate (1), said step comprising the following operations:
Forming a perforated layer (6) on the crystalline holding substrate (1A);
Growing a crystal layer (1B) on the porous layer (6);
The whole [holding substrate (1A) \ porous layer (6) \ crystal layer (1B)] hits the donor substrate (1), and the porous layer (6) becomes brittle in the donor substrate (1). The method according to claim 8, which corresponds to an area.   11. A method according to any of claims 1 to 10, characterized in that the material removal in step (d) comprises a selective chemical etching.   12. A method according to any one of the preceding claims, characterized in that the vitreous layer (4) formed in step (b) is electrically insulated. The vitreous layer formed at step (b) (4) addressing, characterized in that a SiO _2, Process according to claim 12. The possible donor substrate (1) is Si; and the strained layer (2) is characterized in that it is a _{Si 1-x} Ge _x, the method according to any one of claims 13 claim 1. The donor substrate (1) comprises a Si bulk holding substrate (1-1) and a buffer structure (1-2, 1-3) adapted to lattice parameters from Si to Si _1-z Ge _z ;
Characterized in that it comprises said strained layer (2) is Si strained layer (2-1) and _{x> Si 1-x} Ge x strained layer of z (2-2), of claims 1 to 14 The method according to any one. The layer grown in step (b1) is Si;
The controlled process performed in step (b2) converts at least a portion of the Si of the layer formed in step (b1) to SiO ₂ , thereby forming the SiO ₂ glassy layer (4). 16. The method according to claim 5, 13, 13, 14 or 15, characterized in that it is a process. The donor substrate (1) is Si, and the controlled process converts at least a portion of Si in the surface layer (1B) to SiO ₂ , thereby forming the second SiO ₂ glassy layer. The method according to claim 5, wherein the method is a controlled thermal oxidation treatment.   18. The method according to claim 17, further comprising the step of removing the second vitreous layer (8) by a chemical treatment based on hydrofluoric acid after step (e).   Method according to claim 3, characterized in that the material used for growth on the structure after the removal of the second vitreous layer (8) is Si.   The vitreous layer (4) formed in step (b) is electrically insulated, and the formed structure is a semiconductor-on-insulator structure, wherein the semiconductor portion of the semiconductor-on-insulator structure is The method according to any of the preceding claims, comprising a strained layer (2) relaxed or pseudo-relaxed in step (e).   20. A method according to any of the preceding claims, further comprising epitaxially growing a layer on the relaxed or pseudo relaxed layer (2 ').

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