CN118077032A - Method for producing a composite structure of a thin film containing monocrystalline SiC on a carrier substrate of polycrystalline SiC - Google Patents

Method for producing a composite structure of a thin film containing monocrystalline SiC on a carrier substrate of polycrystalline SiC Download PDF

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Publication number
CN118077032A
CN118077032A CN202280067022.2A CN202280067022A CN118077032A CN 118077032 A CN118077032 A CN 118077032A CN 202280067022 A CN202280067022 A CN 202280067022A CN 118077032 A CN118077032 A CN 118077032A
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layer
carrier substrate
silicon carbide
surface layer
manufacturing
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H·比亚尔
I·拉杜
F·阿利伯特
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Soitec SA
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Soitec SA
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Priority claimed from PCT/FR2022/051774 external-priority patent/WO2023057700A1/en
Publication of CN118077032A publication Critical patent/CN118077032A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02002—Preparing wafers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
    • H01L21/76—Making of isolation regions between components
    • H01L21/762—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers
    • H01L21/7624—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology
    • H01L21/76251—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques
    • H01L21/76259—Dielectric regions, e.g. EPIC dielectric isolation, LOCOS; Trench refilling techniques, SOI technology, use of channel stoppers using semiconductor on insulator [SOI] technology using bonding techniques with separation/delamination along a porous layer

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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Laminated Bodies (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Recrystallisation Techniques (AREA)

Abstract

The present invention relates to a method for manufacturing a composite structure comprising a thin film of single crystal silicon carbide on a carrier substrate of polycrystalline silicon carbide, the method comprising: a) providing an initial monocrystalline silicon carbide substrate having a front side and a back side and a polycrystalline silicon carbide carrier substrate having a front side and a back side, b) making the initial substrate porous to form a porous layer at least on the front side of the initial substrate, c) forming a surface layer of amorphous silicon carbide on the porous layer on the front side of the carrier substrate and/or after, d) assembling the initial substrate and the carrier substrate at their respective front sides to obtain a first intermediate structure, e) a heat treatment step applied to the first intermediate structure at a temperature higher than 900 ℃ to crystallize the surface layer at least partially in the form of monocrystalline silicon carbide starting from the contact interface with the porous layer to form the thin film, e) creating a second intermediate structure, f) a separation step performed in the porous layer of the second intermediate structure to obtain a composite structure on the one hand and the remainder of the initial substrate on the other hand.

Description

Method for producing a composite structure of a thin film containing monocrystalline SiC on a carrier substrate of polycrystalline SiC
Technical Field
The present invention relates to the field of semiconductor materials for microelectronic components. The invention relates in particular to a method for producing a composite structure comprising a thin layer of monocrystalline silicon carbide on a carrier substrate made of polycrystalline silicon carbide.
Background
SiC is increasingly being used to fabricate innovative power devices to meet the increasing demands of electronic applications, such as in particular electric vehicles.
Single crystal silicon carbide based power devices and integrated power supply systems are capable of managing much higher power densities than their conventional silicon equivalent and can be managed with smaller sized active areas. To further limit the size of the power devices on silicon carbide, it would be advantageous to fabricate vertical components instead of lateral components. For this purpose, the structure must allow vertical conduction between the electrodes provided on the front side and the electrodes provided on the back side of the SiC structure.
However, high quality single crystal SiC (c-SiC) substrates for the microelectronics industry are still expensive and difficult to supply in large sizes. Thus, advantageously, the layer transfer solution is used to manufacture composite structures that typically comprise thin layers of single crystal SiC (obtained from high quality c-SiC substrates) on low cost carrier substrates made of, for example, polycrystalline SiC (p-SiC).
One well-known thin layer transfer solution is SmartA process that uses implantation of light ions in a single crystal donor substrate and is bonded to a carrier substrate by direct bonding at a bonding interface. The transfer of the thin layer obtained from the donor substrate to the carrier substrate is performed by fracture along the buried weak plane created by the light ion implantation.
Another known transfer method, in particular for silicon substrates, isA method comprising epitaxially growing a porous layer of a thin monocrystalline layer thereon and bonding to a carrier substrate by direct bonding. The transfer of the thin layer to the carrier substrate takes place by separation in the porous layer.
Object of the invention
The present invention relates to alternatives to the prior art. The invention relates to a method for producing a composite structure comprising a thin layer made of monocrystalline SiC on a carrier substrate made of polycrystalline SiC. The invention also relates to an intermediate structure obtained during said manufacturing process.
Disclosure of Invention
The invention relates to a method for producing a composite structure comprising a thin layer made of monocrystalline silicon carbide on a carrier substrate made of polycrystalline silicon carbide, comprising:
a) A step of providing an initial substrate made of single crystal silicon carbide having a front side and a back side and a carrier substrate made of polycrystalline silicon carbide having a front side and a back side,
B) A porosification step applied to the initial substrate to form a porous layer on at least a front side of the initial substrate,
C) A step of forming a surface layer made of amorphous silicon carbide on the front surface of the carrier substrate and/or on the porous layer,
D) The step of bonding the initial substrate and the carrier substrate at their respective front faces, results in the creation of a first intermediate structure,
E) A heat treatment step applied to said first intermediate structure at a temperature higher than 900 ℃ in order to crystallize at least partially said surface layer in the form of monocrystalline silicon carbide starting from the contact interface with said porous layer, so as to form a thin layer, step e) resulting in the production of a second intermediate structure,
F) A separation step in the porous layer of the second intermediate structure in order to obtain, on the one hand, the composite structure and, on the other hand, the remainder of the initial substrate.
According to other advantageous and non-limiting features of the invention, considered alone or in any technically feasible combination:
At the end of step b), the thickness of the porous layer is 0.5 μm to 5 μm.
At the end of step b), the porous layer comprises pores with a size of 1nm to 50nm and has a porosity of 10% to 70%.
At the end of step c), the thickness of the surface layer is less than or equal to 10 μm.
At the end of step c), the thickness of the surface layer is less than or equal to 1 μm, typically on the order of 100 nm to several hundred nm.
Step c) comprises depositing an amorphous silicon carbide layer at least on the front side of the carrier substrate and/or at least on the porous layer to form the surface layer.
The deposited amorphous silicon carbide layer is highly doped and has a dopant species concentration greater than 10 19/cm3 or greater than 10 20/cm3.
Step c) comprises amorphizing the surface layer of the carrier substrate at least on its front side to form the surface layer.
Step d) comprises, before bonding the initial substrate and the carrier substrate, forming a bonding layer on one and/or the other of the substrates, on the respective face sides of the substrates, the bonding layer having a total thickness, after bonding, of less than or equal to 10nm.
The bonding layer is composed of at least one material selected from the group consisting of silicon, nickel, titanium, and tungsten.
During step e), the separation into nodules (nodules) or dissolution of the bonding layer allows at least partial direct contact between the surface layer and the porous layer or between the surface layer and the carrier substrate.
The heat treatment of step e) is carried out at a temperature higher than or equal to 1000 ℃, preferably higher than or equal to 1400 ℃, or higher than or equal to 1850 ℃.
In step e), crystallization of the surface layer takes place at least partly in the form of polycrystalline silicon carbide starting from the contact interface with the carrier substrate, so as to form an intermediate layer.
The manufacturing method comprises, after step f), a finishing step g) comprising a mechanical and/or chemical treatment of the composite structure to remove residues of the porous layer from the front face of the thin layer and/or to correct the thickness uniformity of the composite structure.
Step g) comprises applying a heat treatment to the composite structure at a temperature of 1000 ℃ to 1900 ℃ before or after the mechanical and/or chemical treatment.
The manufacturing method comprises the steps of: the remainder of the initial substrate is reconditioned (reconditioning) for reuse as an initial substrate for manufacturing a new composite structure.
The invention also relates to an intermediate structure comprising:
A carrier substrate made of polycrystalline silicon carbide,
At least one surface layer made of amorphous silicon carbide, which is located on the carrier substrate, on its front side,
A porous layer on said surface layer,
An initial substrate made of silicon carbide single crystal on the porous layer,
The porous layer being positioned on the surface layer in direct contact or via a bonding layer, there being a bonding interface between the porous layer and the surface layer, or
The surface layer being positioned on the carrier substrate in direct contact or via a bonding layer, there being a bonding interface between the carrier substrate and the surface layer, or
The surface layer on the porous layer side is positioned on the other surface layer on the carrier substrate side either in direct contact or via a bonding layer, there being a bonding interface between the two surface layers.
Drawings
Other features and advantages of the present invention will become apparent from the following detailed description of the invention given with reference to the accompanying drawings in which:
FIG. 1 shows a composite structure produced using a manufacturing method according to the present invention;
[ FIG. 2a ]
[ FIG. 2b ]
[ FIG. 2c ]
[ FIG. 2c ]
[ FIG. 2d ]
[ FIG. 2d' ]
[ FIG. 2d "]
[ FIG. 2e ]
[ FIG. 2f ]
Fig. 2g fig. 2a to 2g show steps of the manufacturing method according to the invention.
The figures are schematic representations for ease of reading and are not drawn to scale. In particular, the thickness of the layer along the z-axis is not proportional to the lateral dimensions along the x-axis and the y-axis; the relative thicknesses of these layers with respect to each other are not necessarily considered in the figures.
Detailed Description
The present invention relates to a method for manufacturing a composite structure 100, which composite structure 100 comprises a thin layer 1 of silicon carbide single crystal (c-SiC will be used hereinafter to refer to silicon carbide single crystal) on a silicon carbide carrier substrate 20 (fig. 1). The carrier substrate 20 is polycrystalline (p-SiC).
The method first comprises a step a) of providing an initial substrate 10 made of monocrystalline silicon carbide (fig. 2 a). The initial substrate 10 is preferably in the form of a wafer having a diameter of 100mm, 150mm, 200mm or 300mm and a thickness of typically 300 to 800 microns. It has a front face 10a and a back face 10b. The surface roughness of the front face 10a is advantageously chosen to be less than 1nm Ra (average roughness), measured by Atomic Force Microscopy (AFM), for example on a 20 micron x 20 micron scan. The initial substrate 10 may be a 4H or 6H polytype and may have n-type or p-type doping.
Step a) further comprises providing a carrier substrate 20 (fig. 2 a) made of polycrystalline silicon carbide having a front side 20a and a back side 20 b.
The carrier substrate 20 may be produced by conventional techniques such as sintering or chemical vapor deposition. It preferably has the same form as the initial substrate 10, typically in the form of a wafer having the typical diameter and thickness mentioned above with reference to the initial substrate 10. The surface roughness of the front side 20a of the carrier substrate 20 is advantageously chosen to be less than 1nm Ra, at least when this side is intended to be directly bonded in a subsequent step d) of the process.
The method then comprises step b): the initial substrate 10 is subjected to porosification to form a porous layer 11 (fig. 2 b). Known methods of porosification of silicon carbide, some of which are referenced after being described in publication Y.Shishkin et al ("Photoelectrochemical etching of n-type 4H silicon carbide",Journal of Applied Physics 96,2311,2004)and by Gautier et al.("Electrochemical formation of porous silicon carbide for micro-device applications",Materials Science Forum,ISSN:1662-9752,Vol.924,pages 943-946,2018), may be applied to the initial substrate 10 to form the porous layer 11.
Advantageously, the thickness of the porous layer 11 is between 0.5 μm and 5 μm; the porosity is preferably between 10% and 70%, the size of the pores being generally between 1nm and 50nm.
These properties are advantageous, firstly the crystallization in contact with the porous layer 11 of the layer 21 made of amorphous silicon carbide in monocrystalline form (step e) of the method), which layer is intended to form the thin layer 1 of the composite structure 100; secondly, in step f) of the method, the characteristics of the porous layer 11 are adapted to allow and promote separation within the layer, while providing sufficient mechanical strength during the preceding step.
The next step c) of the manufacturing method according to the invention corresponds to the formation of the surface layers 21, 12 made of amorphous silicon carbide on at least the front sides 20a,10a of the carrier substrate 20 or the starting substrate 10.
According to the first embodiment, the substrate 20 is provided with said surface layer 21 (fig. 2 c) made of amorphous silicon carbide (a-SiC) at least on its front face 20 a.
According to the second embodiment, the surface layer 12 made of amorphous silicon carbide is formed on at least the front surface 10a of the initial substrate 10, i.e. on the porous layer 11 (fig. 2 c').
According to the third embodiment, the surface layer 21 is formed on the front surface 20a of the carrier substrate 20, and the other surface layer 12 is formed on the porous layer 11, which itself is located on the initial substrate 10.
In one or the other of the above embodiments, the surface layers 21, 12 may also be formed on the back surfaces 20b,10b of the substrates 20, 10.
Regardless of the embodiment, the surface layers 21, 12 advantageously have a total thickness of less than or equal to 10 μm.
To form this surface layer 21, 12, according to a first variant, step c) comprises depositing an a-SiC layer on the substrate 20, 10 in question. The deposition of amorphous SiC may be performed by Chemical Vapor Deposition (CVD) techniques, such as Plasma Enhanced CVD (PECVD) or direct liquid jet CVD (DLI-CVD), by physical vapor deposition techniques, or by any other known technique. In the case of CVD deposition, deposition temperatures below 1100 ℃ or below 1000 ℃ are preferred; regarding the deposition precursor (methane or silane chemistry), the C/Si ratio will preferably be chosen to be greater than or equal to 1.
The mentioned deposition technique makes it possible to form the surface layers 21, 12, the thickness of which can typically vary between 100nm and 10 μm, for example about 1 μm. Similarly, when the surface layer 21, 12 made of a-SiC is formed by one of these techniques, the doping thereof can be easily adjusted by the surface layer 21, 12 made of a-SiC. It may be notably highly doped (typically n-type, but optionally p-type): to this end, it includes a dopant species at a concentration greater than 10 19/cm3 or greater than 10 20/cm3. It should be remembered that the surface layers 21, 12 are intended to crystallize at least partially in monocrystalline form so as to form the thin layer 1 of the composite structure 100; it may therefore be highly doped in order to produce a thin layer 1 with low resistivity, depending on the requirements of the intended application.
According to a second variant, step c) comprises amorphization of the surface layer of the substrate in question, so as to form the surface layers 21, 12 made of a-SiC. Such amorphization may be performed by known techniques, such as ion bombardment (e.g. with Si or C ions) or neutron bombardment, with suitable energy to form amorphous layers 21, 12 of the desired thickness.
In the case of amorphization of the surface layer of the substrate 20 (first embodiment and third embodiment), the polycrystalline structure of the carrier substrate 20 may be amorphized, for example by ion bombardment.
According to this second variant of the formation of the surface layer 21, 12, the thickness of the surface layer 21, 12 is preferentially smaller than 1 μm, typically in the order of one hundred to several hundred nanometers.
The manufacturing method according to the invention next comprises a step d) involving joining the initial substrate 10 and the carrier substrate 20 at the respective front faces 10a,20a of the initial substrate 10 and the carrier substrate 20 (fig. 2d, fig. 2d', fig. 2d ").
In the first embodiment (fig. 2 d), the porous layer 11 and the surface layer 21 are thus combined along the bonding interface 3, resulting in obtaining a first intermediate structure 30.
In a second embodiment (fig. 2d '), the surface layer 12 is bonded to the carrier substrate 20 along the bonding interface 3', resulting in a first intermediate structure 30'.
Finally, in the third embodiment (fig. 2d "), the surface layers 22, 12 formed on the carrier substrate 20 and the porous layer 11, respectively, are connected along the bonding interface 3", resulting in obtaining a first intermediate structure 30".
As will be explained below, irrespective of the embodiment, the bonding interface 3,3',3 "in step d) may comprise a direct contact between the joined surfaces or an indirect contact between the surfaces joined by a bonding layer.
The bonding of step d) is based on direct bonding by molecular adhesion. As is known per se, such bonding does not require an adhesive material, since the bonding is performed at the atomic level between the joining surfaces. There are several types of molecular adhesion bonding that differ particularly in terms of temperature, pressure, atmospheric conditions or handling prior to contacting the surface. Mention may be made of room temperature bonding, atomic Diffusion Bonding (ADB), surface Activated Bonding (SAB), etc., with or without prior plasma activation of the surfaces to be joined.
Prior to contacting the surfaces to be joined, the joining step d) may comprise a conventional sequence of chemical cleaning (e.g. RCA cleaning) and surface activation (e.g. by means of an oxygen or nitrogen plasma) or other surface preparation (e.g. scrubbing), which may promote the quality (low defect density, high adhesion energy) of the bonding interface 3,3',3 ".
As previously mentioned and optionally, step d) comprises, before bringing the faces of the substrates 20, 10 to be joined into contact, forming a bonding layer on one and/or the other of said faces. Thus, the bonding layer may be deposited (e.g. by chemical vapor deposition CVD) on the porous layer 11 and/or the surface layer 21 (in the first embodiment), directly on the carrier substrate 20 and/or the surface layer 12 (in the second embodiment), or on one and/or the other of the surface layers 22, 12 (in the third embodiment).
The bonding layer may be composed of at least one material selected from silicon, nickel, titanium, tungsten, and the like. Preferably, its thickness is reduced, typically its total thickness is less than or equal to 10nm, or less than or equal to 5nm. In this first embodiment, it is critical that the bonding layer has a small thickness that enables the bonding layer to be divided or dissolved in the form of nodules during the subsequent heat treatment of step e): this then provides at least partially a direct contact between the porous layer 11 and the surface layer 21: this direct contact is necessary for the correct implementation of the crystallization that occurs in the next step e). If the bonding layer is made of a semiconductor material, such as silicon in particular, it may be doped to promote vertical conduction.
As shown in fig. 2d, in a first embodiment of the invention, the first intermediate structure 30 resulting from step d) comprises starting from the carrier substrate 20 and thus in the reverse order to that seen in the figure:
a carrier substrate 20 made of polycrystalline silicon carbide with a rear face 20b,
A surface layer 21 made of amorphous silicon carbide, which is provided on the carrier substrate 20, on the front face 20a side thereof,
A porous layer 11 positioned on the surface layer 21 in direct contact or via a bonding layer, the bonding interface 3 being present between the porous layer 11 and the surface layer 21,
An initial substrate 10 made of monocrystalline silicon carbide on the porous layer 11 and in contact with the porous layer 11.
Fig. 2d 'shows a first intermediate structure 30' resulting from step d) in a second embodiment of the invention, comprising:
a carrier substrate 20 made of polycrystalline silicon carbide,
A surface layer 12 made of amorphous silicon carbide, which is positioned on the carrier substrate 20 in direct contact or via a bonding layer, on the front side 20a side thereof, there being a bonding interface 3' between the carrier substrate 20 and the surface layer 12,
A porous layer 11 on the surface layer 12,
An initial substrate 10 made of monocrystalline silicon carbide on the porous layer 11 and in contact with the porous layer 11.
Finally, fig. 2d "shows a first intermediate structure 30" resulting from step d) in a third embodiment of the invention; it comprises the following steps:
a carrier substrate 20 made of polycrystalline silicon carbide,
A surface layer 21 made of amorphous silicon carbide, which is provided on the carrier substrate 20, on the front face 20a side thereof,
A further surface layer 12 made of amorphous silicon carbide, which is positioned on the surface layer 21 in direct contact or via a bonding layer, there being a bonding interface 3 "between the two surface layers 21, 12,
A porous layer 11 on the surface layer 12,
An initial substrate 10 made of monocrystalline silicon carbide on the porous layer 11 and in contact with the porous layer 11.
The next step e) of the manufacturing method involves a heat treatment applied to the first intermediate structure 30, 30',30 "at a temperature higher than 900 ℃ in order to crystallize the surface layers 21, 12 (fig. 2 e). The temperature of the heat treatment is advantageously greater than or equal to 1000 ℃, or greater than or equal to 1400 ℃, or even greater than or equal to 1850 ℃. For example, for the 1 μm surface layer 21, 12 made of a-SiC, a heat treatment at 1700 ℃ for 30 minutes may be applied.
Starting from the direct contact interface between the porous layer 11 (the silicon carbide of which has a single-crystal structure) and the surface layers 21, 12 made of a-SiC, the surface layers 21, 12 crystallize in the form of single-crystal silicon carbide via a solid-phase epitaxy phenomenon. The surface layer crystallized in a single crystal form forms a thin layer 1.
Only a portion of the surface layers 21, 12 may be crystallized in monocrystalline form. This is because crystallization may occur at least in part in the form of polycrystalline silicon carbide from the contact interface with the carrier substrate 20: an intermediate layer 22 is then formed extending the p-SiC of the carrier substrate 20 to the thin layer 1 made of c-SiC. In other words, the intermediate layer 22 is interposed between the carrier substrate 20 and the thin layer 1. The interface between the intermediate layer 22 and the thin layer 1 has the advantage of being completely closed, since it is defined by the convergence of the c-SiC and p-SiC crystallization fronts by the same a-Si material (surface layers 21, 12). This is an interesting advantage compared to a bonding interface between two materials with different crystal properties (e.g. p-SiC/c-SiC), the complete closure of which is significantly dependent on the roughness and surface finish of the materials before joining.
In order to obtain such an intermediate layer 22, if the surface layer 21 is not present on the carrier substrate 20 (i.e., in the second embodiment), it is notably provided that the surface layer 12 made of a-Si (on the porous layer 11 side) is in direct contact with the carrier substrate 20 without the presence of a bonding layer or by using a discontinuous bonding layer. For example, a bonding layer of a set of nodules is formed between which the carrier substrate 20 is in direct contact with the surface layer 12.
Step e) results in obtaining a second intermediate structure 40, independently of the implementation, in which all or part of the surface layers 21, 12 are crystallized in monocrystalline form to form a thin layer 1 (fig. 2 e).
The manufacturing method finally comprises a step f) of separation in the porous layer 11 of the second intermediate structure 40, so as to obtain, on the one hand, the composite structure 100 and, on the other hand, the remainder 10' of the initial substrate (fig. 2 f).
The separation step f) is performed by applying mechanical stress to the second intermediate structure 40. The stress may be applied by pressing and/or inserting a tool (e.g., a blade or other sloped shape) on the edge of the intermediate structure 40 opposite the porous layer 11. Alternatively, the mechanical stress may be applied by water jets or air jets, towards the edges of the structure 40, still opposite the porous layer 11. Regardless of the separation technique used, the applied mechanical stress must be adapted to propagate a fracture wave in the porous layer 11, which has a lower mechanical strength compared to other layers or interfaces in the second intermediate structure 40.
By carefully protecting the free surface of the second intermediate structure 40, separation may optionally be facilitated by lateral chemical etching of the porous layer 11.
At the end of the separation step f), the free face 1a of the thin layer 1 of the composite structure 100 may have a residue 11r of porous layer (fig. 2 f) in the same way as the front face 10'a of the remainder 10' of the initial substrate.
Thus, the method according to the invention may comprise a step g) of mechanical and/or chemical treatment of the composite structure 100 in order to remove the residues 11r of the porous layer 11 from the front face 1a of the thin layer 1 and/or to correct the thickness uniformity of the composite structure 100 (fig. 2 g).
Step g) may comprise Chemical Mechanical Polishing (CMP) and/or chemical or plasma treatment (etching or cleaning) and/or mechanical treatment (grinding) to remove the residues 11r.
Step g) may also comprise a cleaning operation of the Caro (piranha etch) and/or SC1/SC2 (standard cleaning 1, standard cleaning 2) and/or HF (hydrofluoric acid) type, or N2, ar or CF4 plasma, to further improve the quality of the free face 1a of the thin layer 1.
Step g) may comprise treating the composite structure 100 at a temperature between 1000 ℃ and 1900 ℃ for about 1 hour up to several hours. The heat treatment may be performed before or after the mechanical and/or chemical treatment described above. The aim is to stabilize the composite structure 100 by significantly developing the crystalline quality of the thin layer 1, where appropriate, so that the structure 100 is fully compatible with subsequent heat treatments at the very high temperatures required for manufacturing components on and/or in the layer 1.
Finally, the manufacturing method may include the step of reconditioning the remaining portion 10' of the initial substrate in order to be reused as the initial substrate 10 for a new composite structure 100 (fig. 2 g). Similar to those applied to the composite structure 100 to remove the residue 11r, mechanical and/or chemical treatments may be applied to the front side 10'a of the remaining substrate 10'. The reconditioning step may further include one or more treatments of the edges of the remaining substrate 10 'and/or its backside 10' b by chemical mechanical polishing, grinding, and/or dry or wet chemical etching.
Of course, the invention is not limited to the embodiments and examples already described, and modified embodiments may be added thereto without departing from the scope of the invention as defined by the claims.

Claims (17)

1. A method for manufacturing a composite structure (100) comprising a thin layer (1) of monocrystalline silicon carbide on a carrier substrate (20) of polycrystalline silicon carbide, the method comprising:
a) Providing an initial substrate (10) made of single crystal silicon carbide having a front side (10 a) and a back side (10 b) and a carrier substrate (20) made of polycrystalline silicon carbide having a front side (20 a) and a back side (20 b),
B) A step of porosification applied to the initial substrate (1) so as to form a porous layer (11) at least on the front side (10 a) of the initial substrate (10),
C) A step of forming a surface layer (21, 12) made of amorphous silicon carbide on the front surface (20 a) of the carrier substrate (20) and/or on the porous layer (11),
D) The step of bonding said initial substrate (10) and said carrier substrate (20) at their respective front faces results in the creation of a first intermediate structure (30, 30',30 "),
E) A heat treatment step applied to said first intermediate structure (30, 30') at a temperature higher than 900 ℃ in order to crystallize at least partially said surface layer (21, 12) in the form of monocrystalline silicon carbide starting from the contact interface with said porous layer (11) so as to form a thin layer (1), step e) resulting in the production of a second intermediate structure (40),
F) -a separation step in the porous layer (11) of the second intermediate structure (40) in order to obtain, on the one hand, the composite structure (100) and, on the other hand, the remainder (10') of the initial substrate.
2. Manufacturing method according to the previous claim, wherein at the end of step b) the thickness of the porous layer (11) is 0.5 μm to 5 μm.
3. The manufacturing method according to any one of the preceding claims, wherein at the end of step b) the porous layer (11) comprises pores with a size of 1nm to 50nm and has a porosity of 10% to 70%.
4. The manufacturing method according to any one of the preceding claims, wherein at the end of step c) the thickness of the surface layer (21, 12) is less than or equal to 10 μm.
5. The manufacturing method according to any one of the preceding claims, wherein at the end of step c) the thickness of the surface layer (21, 12) is less than or equal to 1 μm, typically in the order of 100 nm to several hundred nm.
6. The method of manufacturing according to any one of the preceding claims, wherein step c) comprises depositing an amorphous silicon carbide layer at least on the front side (20 a) of the carrier substrate (20) and/or at least on the porous layer (11) to form the surface layer (21, 12).
7. The method of manufacturing of the preceding claim, wherein the deposited amorphous silicon carbide layer is highly doped and has a dopant species concentration of greater than 10 19/cm3 or greater than 10 20/cm3.
8. The manufacturing method according to any one of claims 1 to 5, wherein step c) comprises amorphizing a surface layer of the carrier substrate (20) at least on its front side (20 a) side to form the surface layer (21).
9. The manufacturing method according to any one of the preceding claims, wherein step d) comprises, before joining the initial substrate (10) and the carrier substrate (20), forming a bonding layer on one and/or the other of the substrates on the respective front side of the substrates,
After bonding, the total thickness of the bonding layer is less than or equal to 10nm.
10. The manufacturing method according to the preceding claim, wherein the bonding layer is composed of at least one material selected from silicon, nickel, titanium and tungsten.
11. The manufacturing method according to any one of the two preceding claims, wherein during step e) the separation or dissolution of the bonding layer allows at least partial direct contact between the surface layer (21) and the porous layer (11) or between the surface layer (12) and the carrier substrate (20).
12. The manufacturing process according to any one of the preceding claims, wherein the heat treatment of step e) is carried out at a temperature higher than or equal to 1000 ℃, preferably higher than or equal to 1400 ℃, or higher than or equal to 1850 ℃.
13. The manufacturing method according to any one of the preceding claims, wherein in step e) crystallization of the surface layer (21, 12) takes place at least partly in the form of polycrystalline silicon carbide starting from the contact interface with the carrier substrate (20) so as to form an intermediate layer (22).
14. Manufacturing method according to any one of the preceding claims, comprising a finishing step g) after step f), said finishing step g) comprising a mechanical and/or chemical treatment of the composite structure (100) to remove residues (11 r) of the porous layer (11) from the front face (1 a) of the thin layer (1) and/or to correct thickness uniformity of the composite structure (100).
15. Manufacturing method according to the preceding claim, wherein step g) comprises applying a heat treatment to the composite structure (100) at a temperature of 1000 ℃ to 1900 ℃ before or after the mechanical and/or chemical treatment.
16. A method of manufacture according to any one of the preceding claims, the method comprising the steps of: the remaining part (10') of the initial substrate is reconditioned for reuse as an initial substrate (10) for manufacturing a new composite structure (100).
17. An intermediate structure (30, 30') comprising:
a carrier substrate (20) made of polycrystalline silicon carbide,
At least one surface layer (21, 12) made of amorphous silicon carbide, which is located on the carrier substrate (20) on its front side (20 a),
A porous layer (11) on said surface layer (21, 12),
An initial substrate (10) made of monocrystalline silicon carbide on said porous layer (11),
The porous layer (11) is positioned on the surface layer (21) in direct contact or via a bonding layer, there is a bonding interface (3) between the porous layer (11) and the surface layer (21), or
The surface layer (12) being positioned on the carrier substrate (20) in direct contact or via a bonding layer, there being a bonding interface (3') between the carrier substrate (20) and the surface layer (12), or
A surface layer (12) on the porous layer (11) side is positioned on the other surface layer (21) on the carrier substrate (20) side either in direct contact or via a bonding layer, a bonding interface (3 ") being present between the two surface layers (21, 12).
CN202280067022.2A 2021-10-07 2022-09-21 Method for producing a composite structure of a thin film containing monocrystalline SiC on a carrier substrate of polycrystalline SiC Pending CN118077032A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FRFR2110626 2021-10-07
FR2110626A FR3128056B1 (en) 2021-10-07 2021-10-07 METHOD FOR MANUFACTURING A COMPOSITE STRUCTURE COMPRISING A THIN MONOCRYSTALLINE SIC LAYER ON A POLY-CRYSTALLINE SIC SUPPORT SUBSTRATE
FRFR2110624 2021-10-07
PCT/FR2022/051774 WO2023057700A1 (en) 2021-10-07 2022-09-21 Method for manufacturing a composite structure comprising a thin film of monocrystalline sic on a carrier substrate of polycrystalline sic

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DE69628505T2 (en) * 1995-07-21 2004-05-06 Canon K.K. Semiconductor substrate and its manufacturing process
FR2810448B1 (en) * 2000-06-16 2003-09-19 Soitec Silicon On Insulator PROCESS FOR PRODUCING SUBSTRATES AND SUBSTRATES OBTAINED BY THIS PROCESS

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