Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/01—Manufacture or treatment
  • H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
  • H10N30/072—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies
  • H10N30/073—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies by fusion of metals or by adhesives
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P90/00—Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
  • H10P90/19—Preparing inhomogeneous wafers
  • H10P90/1904—Preparing vertically inhomogeneous wafers
  • H10P90/1906—Preparing SOI wafers
  • H10P90/1914—Preparing SOI wafers using bonding
  • H10P90/1916—Preparing SOI wafers using bonding with separation or delamination along an ion implanted layer, e.g. Smart-cut
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/01—Manufacture or treatment
  • H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
  • H10N30/085—Shaping or machining of piezoelectric or electrostrictive bodies by machining
  • H10N30/086—Shaping or machining of piezoelectric or electrostrictive bodies by machining by polishing or grinding
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N30/00—Piezoelectric or electrostrictive devices
  • H10N30/80—Constructional details
  • H10N30/85—Piezoelectric or electrostrictive active materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P90/00—Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10W—GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
  • H10W10/00—Isolation regions in semiconductor bodies between components of integrated devices
  • H10W10/10—Isolation regions comprising dielectric materials
  • H10W10/181—Semiconductor-on-insulator [SOI] isolation regions, e.g. buried oxide regions of SOI wafers

Definitions

• the invention relates to a method for manufacturing a donor substrate for transferring a piezoelectric layer, a donor substrate and a method for transferring such a piezoelectric layer onto a support substrate.
• a piezoelectric on insulator (POI) substrate comprises a thin layer of piezoelectric material on a substrate.
• the method used comprises the transfer of the thin piezoelectric layer onto a support substrate from a thicker substrate of piezoelectric material.
• a donor substrate is used in which a bulk substrate of piezoelectric material is assembled to a manipulation substrate by bonding using a polymer layer. Then, the donor substrate undergoes a step of thinning the bulk piezoelectric substrate to form a thinner piezoelectric layer before being assembled to the support substrate. Finally, the transfer of the piezoelectric layer on the support substrate is carried out mechanically or thermally at the level of a fracturing zone created beforehand in the thinned piezoelectric layer.
• the donor substrate is introduced into the process to limit the negative impact of the difference in thermal expansion coefficients between the piezoelectric material and the POI support substrate. Indeed, to reinforce the bonding interface between the different substrates and the transfer of the thin layer, heat treatments are carried out. An example of this type of method is described in WO 2019/186032 A1.
• An object of the invention is to remedy the aforementioned drawbacks and in particular to design a donor substrate for the transfer of a piezoelectric layer from a substrate of piezoelectric material onto a support substrate which has better mechanical strength.
• the object of the invention is achieved by a process for manufacturing a donor substrate for transferring a piezoelectric layer onto a support substrate comprising the steps of providing a handling substrate, in particular a silicon-based substrate, providing a piezoelectric substrate, forming an intermediate layer on a free surface of the piezoelectric substrate, depositing a polymer layer on the intermediate layer of the substrate piezoelectric, and assembling the piezoelectric substrate on the handling substrate to form the donor substrate.
• an intermediate layer between the piezoelectric substrate and the polymer layer makes it possible to obtain a more stable bond between the piezoelectric material and the polymer layer, by choosing an intermediate layer which has good adhesion to the piezoelectric substrate as well as to the polymer layer.
• the method according to the invention makes it possible to obtain a donor substrate having improved mechanical stability between the piezoelectric substrate and the polymer layer of the manipulation substrate compared to the state of the art.
• the object of the invention is also achieved by a method of manufacturing a donor substrate for transferring a piezoelectric layer onto a support substrate comprising the steps of providing a handling substrate, in particular a silicon-based substrate ; depositing a polymer layer on a free face of the handling substrate, providing a piezoelectric substrate, forming an intermediate layer on a free surface of the piezoelectric substrate, assembling the piezoelectric substrate on the handling substrate in such a way that the intermediate layer formed on the substrate piezoelectric is sandwiched between the polymer layer of the manipulation substrate and the piezoelectric substrate to form the donor substrate.
• the formation of an intermediate layer between the piezoelectric substrate and the polymer layer of the manipulation substrate makes it possible to obtain a more stable bond between the piezoelectric material and the polymer layer, by choosing an intermediate layer which has good adhesion to the piezoelectric substrate as well than to the polymer layer.
• the method according to the invention makes it possible to obtain a donor substrate having improved mechanical stability between the piezoelectric substrate and the polymer layer of the manipulation substrate compared to the state of the art.
• the formation of the intermediate layer can comprise the formation of a single layer or of several sub-layers.
• the formation of the intermediate layer may comprise at least the formation of a dielectric layer, in particular a layer based on silicon oxide or nitride oxide or a combination of oxide nitride SiO x N y .
• a dielectric layer formed on a piezoelectric material makes it possible to assemble the piezoelectric substrate to another substrate to form a donor substrate via this dielectric layer. Thanks to the presence of the dielectric layer making the connection between the piezoelectric substrate and the handling substrate, the donor substrate obtained has improved mechanical stability for the various process steps that the donor substrate will then undergo.
• a surface treatment step of the intermediate layer can be carried out, in particular a plasma treatment, even more in particular an oxygen O2 plasma.
• a plasma treatment is a dry treatment which allows the functionalization and/or the activation of the surface.
• Plasma surface treatment consists of a very strong oxidation of the surface of a material. The oxidation of surface molecules makes it possible to increase the surface tension of a support.
• the plasma treatment allows the creation of free radicals on the surface which promote the successive adhesion of a thin layer in contact with these free radicals.
• the plasma surface treatment makes it possible to improve the chemical characteristics of the material for better adhesion to a coating layer.
• the plasma treatment step of the method according to the invention makes it possible to improve the adhesion between the dielectric layer formed on the piezoelectric substrate and the polymer layer of the donor substrate, and results in a mechanical stability of the donor substrate improved by compared to the state of the art.
• a step of thinning the piezoelectric substrate of the donor substrate can be carried out, so as to obtain either a thinned piezoelectric substrate with a thickness t less than ti of the piezoelectric substrate, or a piezoelectric layer of a lower thickness to the thickness ti of the piezoelectric substrate.
• the thinning step can be carried out by a grinding process or else by a chemical etching process of the piezoelectric substrate.
• a thinner piezoelectric substrate or a piezoelectric layer of a thinner desired thickness is obtained and the donor substrate thus manufactured by the method according to the invention can be used as a donor substrate in a subsequent layer transfer process to transfer a thin layer of the piezoelectric material onto a support substrate to thereby form a piezoelectric on insulator (POI) substrate.
• POI piezoelectric on insulator
• the assembly step of the method of manufacturing a donor substrate may comprise a step of processing the polymer layer to obtain a crosslinked polymer layer to bond the manipulation substrate to the piezoelectric substrate.
• the formation of a crosslinked polymer layer by a stage of treatment of the polymer layer is simple to set up and allows an adhesion which satisfies the conditions of the process.
• a donor substrate for the transfer of a piezoelectric layer comprising a handling substrate, in particular a silicon-based substrate, a piezoelectric substrate, a polymer layer sandwiched between the manipulation and the piezoelectric substrate, and characterized in that the donor substrate further includes an intermediate layer sandwiched between the piezoelectric substrate and the polymer layer. Thanks to the presence of the intermediate layer sandwiched between the piezoelectric substrate and the polymer layer, a better bond is achieved between the piezoelectric substrate and the polymer layer. This bonding results in a donor substrate having improved mechanical stability and makes it possible to use this donor substrate in a posteriori processes without encountering problems of separation at the level of the polymer-piezoelectric interface.
• the intermediate layer can comprise a single layer or several sub-layers.
• the intermediate layer may comprise at least one dielectric layer, in particular a layer based on silicon oxide and/or silicon nitride or a combination of nitride and silicon oxide SiO x N y .
• a dielectric layer formed on a piezoelectric material subsequently makes it possible to use the piezoelectric substrate for assembly with another substrate to form a donor substrate via this dielectric layer in a solid and stable manner for the various stages of process that the donor substrate will then undergo.
• the dielectric layer of the intermediate layer can be in direct contact with the polymer layer of the donor substrate.
• the connection between the piezoelectric substrate and the polymer layer of the donor substrate takes place via the dielectric layer, which makes it possible to obtain a stable connection so that the donor substrate subsequently undergoes thermal and/or mechanical process steps without suffer from degradation at the piezoelectric-polymer bond.
• the polymer layer may be a polymerized adhesive layer for bonding the piezoelectric substrate to the handling substrate via the intermediate layer of the piezoelectric substrate.
• the presence of a cross-linked polymer layer makes it possible to obtain a stable bond with the intermediate layer of the piezoelectric substrate.
• the piezoelectric substrate can be a lithium tantalate (LTO), lithium niobate (LNO), aluminum nitride (AIN), lead titano-circonate (PZT), langasite or Langatate.
• LTO lithium tantalate
• LNO lithium niobate
• AIN aluminum nitride
• PZT lead titano-circonate
• langasite langasite
• Langatate The donor substrate according to the invention may comprise these materials, which play a major role in devices exploiting the piezoelectric effect.
• the object of the invention can also be achieved by a method of transferring a piezoelectric layer onto a support substrate comprising the steps of supplying a donor substrate as described previously with a piezoelectric substrate thinned or obtained by placing implementation of the manufacturing process as described before, forming a zone of weakness inside the piezoelectric substrate, providing a support substrate, in particular a silicon-based substrate, attaching the donor substrate to the support substrate, to obtain a substrate assembly donor - support substrate, and making the fracture along the embrittlement zone to separate a piezoelectric layer from the rest of the donor substrate.
• FIG. 1a schematically represents a process for manufacturing a donor substrate and a donor substrate according to a first embodiment of the invention.
• Figure 1b schematically represents a process for manufacturing a donor substrate and a donor substrate according to a first variant of the first embodiment of the invention.
• Figure 2 schematically represents a method of manufacturing a donor substrate and a donor substrate according to a second variant of the first embodiment of the invention.
• Figure 3 schematically represents a process for manufacturing a donor substrate and a donor substrate according to a second embodiment of the invention.
• FIG. 4 schematically represents a method for transferring a piezoelectric layer according to a third embodiment of the invention.
• FIG. 1a schematically illustrates a method of manufacturing a donor substrate used for transferring a piezoelectric layer from the donor substrate onto a support substrate according to a first embodiment of the invention.
• the method of manufacturing a donor substrate begins with step I) of providing a manipulation substrate 100, in particular a bulk substrate.
• a solid substrate is a substrate based on a single material typically with a thickness of between 300 ⁇ m and 800 ⁇ m, in particular between 350 ⁇ m and 800 ⁇ m.
• the manipulation substrate 100 is made of a material whose coefficient of thermal expansion is close to that of the material of the support substrate on which the piezoelectric layer is intended to be transferred.
• close is meant a difference in coefficient of thermal expansion between the material of the manipulation substrate 100 and the material of the support substrate less than or equal to 5%, and preferably equal to or close to 0%.
• the manipulation substrate 100 can be a substrate based on silicon, sapphire, aluminum nitride (AIN), silicon carbide (SiC) or even gallium arsenide (GaAs). Handling substrate 100 can be a crystalline or polycrystalline substrate.
• a piezoelectric substrate 106 is provided. It is preferably a solid substrate formed from a single piezoelectric material, the thickness of which is typically of the order of at least 300 ⁇ m, preferably at least 350 ⁇ m. According to a variant, the substrate of piezoelectric material 106 can also be a thick layer of piezoelectric material between 25 ⁇ m and 50 ⁇ m, formed on another substrate.
• the piezoelectric material can, for example, be Lithium Tantalate (LTO), Lithium Niobate (LNO), Aluminum Nitride (AIN), Lead Titano-Circonate (PZT), Langasite or Langatate .
• LTO Lithium Tantalate
• LNO Lithium Niobate
• AIN Aluminum Nitride
• PZT Lead Titano-Circonate
• a step III) of forming an intermediate layer 108 on a free surface 110 of the piezoelectric substrate 106 is carried out.
• the formation of the intermediate layer 108 on the free surface 110 of the piezoelectric substrate can be carried out by deposition by spin coating, or “spin coating” in English terminology, or by a thermal or plasma-assisted growth technique such as PECVD or PVD.
• the intermediate layer 108 formed on the piezoelectric substrate 106 is a dielectric layer, for example a layer based on silicon oxide, or based on silicon nitride SisISk, or even a layer comprising a combination of nitride and silicon oxide SiO x N y .
• a step 118 of activating the surface of the intermediate layer 108 formed on the piezoelectric substrate 106 can be carried out to activate the free surface 120 of the intermediate layer 108.
• this treatment of activation 118 may be a plasma treatment, even more particularly an oxygen-based plasma treatment.
• a plasma treatment is a dry treatment that allows the functionalization, activation or cleaning of the surface, or a combination of these effects by oxidation.
• the oxidation of surface molecules increases the surface tension of a support creating dangling bonds on the surface.
• the plasma treatment allows the creation of free radicals on the surface which promote the successive adhesion of a thin layer in contact with these free radicals.
• the plasma surface treatment makes it possible to improve the chemical characteristics of the surface 120 of the dielectric layer 108 of the piezoelectric substrate 106 by creating dangling bond sites for better adhesion to a layer which is formed or placed in contact with the surface 120 of layer 108 of piezoelectric substrate 106 during the rest of the method.
• a step IV) of depositing a polymer layer 104 on the intermediate layer 108 of the piezoelectric substrate 106 is carried out.
• the polymer layer 104 is thus in direct contact with the intermediate layer 108 of the piezoelectric substrate 106 at the interface 126.
• the presence of the intermediate layer 108 between the piezoelectric substrate 106 and the polymer layer 104 results in better adhesion with the polymer layer. 104, and thus, with the piezoelectric substrate 106, compared to a direct connection between the polymer layer 104 and the piezoelectric substrate 106 of the state of the art. Indeed, it is possible to choose an intermediate layer 108 which has good adhesion to the piezoelectric substrate 106 as well as to the polymer layer 104.
• the deposition of the polymer layer 104 is advantageously carried out by spin coating, or "spin coating" in English terminology.
• This technique consists in rotating the substrate on which the deposition of the polymer layer 104 is provided on itself at a given speed, in order to spread said polymer layer 104 uniformly over the entire surface of the piezoelectric substrate 106 by centrifugal force.
• the piezoelectric substrate 106 is typically placed and held by drawing a vacuum on a turntable.
• the thickness of the polymer layer 104 obtained depends on the parameters used during the deposition of the layer, that is to say, for example, the speed and duration of rotation of the substrate and the volume of the polymer solution deposited on the surface of the substrate 106.
• the thickness of the polymer layer 104 is typically between 1 ⁇ m and 6 ⁇ m, preferably 3.5 ⁇ m.
• the polymer layer 104 can be a photo-polymerizable layer, in particular based on thiol-ene resin.
• the layer marketed under the reference "NOA 61" by the company NORLAND PRODUCTS can be used in the present invention as polymer layer 104.
• a heat treatment can be carried out to improve the adhesion of the polymer layer 104 to the activated surface 120 of the intermediate layer 108 of the piezoelectric substrate 106.
• the step of depositing the polymer layer 104 is carried out after the step of activating 118 the surface 120 of the intermediate layer 108.
• the deposition of the polymer layer 104 is carried out on the activated surface 120 of the intermediate layer 108, in direct contact with the activated surface 120.
• the piezoelectric substrate 106 obtained after step IV is then assembled to the manipulation substrate 100 obtained in step I) during an assembly step V) to form the donor substrate 124.
• the assembly of the piezoelectric substrate 106 on the manipulation substrate 100 is made such that the polymer layer 104 is positioned in contact with the layer 108 of the piezoelectric substrate 106 and the manipulation substrate 100.
• a bonding step VI) is carried out to bond the piezoelectric substrate 106 to the handling substrate 100 to form a stable donor substrate 128.
• Polymer layer 104 undergoes cross-linking treatment 130 to modify the mechanical properties of polymer layer 104.
• Cross-linking is the general term for the process of forming covalent bonds or relatively short sequences of chemical bonds to join two polymer chains. When the polymer chains are cross-linked, the polymer layer 104 becomes stiffer. Covalent chemical crosslinks are mechanically and thermally stable, so once formed they are difficult to break.
• a crosslinking treatment 130 can be carried out by using heat, pressure, by a change in pH or by irradiation. According to the invention, the crosslinking treatment 130 can be carried out by irradiation by a luminous flux 130 of the polymer layer 104. The irradiation 130 is carried out through the piezoelectric substrate 106 or the substrate 100 to crosslink the polymer layer 104 and obtain a crosslinked polymer layer 132 or also called polymerized layer 132 .
• the irradiation 130 can be carried out using a light source, preferably a laser.
• the light radiation 130, or light flux is preferably ultra-violet (UV) radiation, preferably with a wavelength between 320 nm and 365 nm.
• UV ultra-violet
• the thickness of the crosslinked polymer layer 132 is preferably between 1 ⁇ m and 6 ⁇ m, in particular around 3.5 ⁇ m. This thickness depends in particular on the material of the polymer layer 104 deposited before bonding, on the thickness of said polymer layer 104 and on the irradiation conditions.
• the crosslinking of the polymer layer 104 by UV irradiation 130 makes it possible to release radicals which will trigger the polymerization of the polymer layer 104.
• the polymerization of the polymer layer 104 results in chemical bonds which are mechanically and thermally stable, so that once formed, they are difficult to break.
• the bond between the polymerized layer 132 and the dielectric intermediate layer 108 thus ensures the mechanical cohesion of the donor substrate 128, by maintaining glued together the handling substrate 100 and the piezoelectric substrate 106 which form the donor substrate 128.
• the adhesion between the crosslinked polymer layer 132 and the dielectric layer 108 of the piezoelectric substrate 106 at the interface 126 is improved due to to the activated surface of the intermediate layer 108.
• the dangling bonds present on the activated surface of the dielectric intermediate layer 108 of the piezoelectric substrate 106 will form covalent bonds with the dangling bonds present at the surface of the polymer layer 104.
• the contact interface 126 between the intermediate layer 108 of the piezoelectric substrate 106 and the polymer layer 104 is consolidated/reinforced thanks to the surface activation treatment of the intermediate layer 108 and results in a mechanical stability of the donor substrate 124 improved compared to the state of the art.
• step III) of the method for forming an intermediate layer 108 is replaced by the formation of a plurality 112 of sub-layers 114, each sub-layer layers 114 of the plurality 112 of sub-layers 114 being the same or being different by their material or by their properties or else by their thicknesses. All other steps I to II and IV to VI are the same as described for Figure 1a. Thus, for a detailed description of these steps, reference is made to the description of Figure 1a.
• At least one layer 116 of the sub-layers 114 of the plurality 112 of sub-layers is a dielectric layer 116, in particular a layer based on silicon oxide, or SisN4 nitride oxide or a combination of oxide SiO x N y .
• the upper layer 116 which corresponds to the last layer of the plurality 112 of sub-layers 114 starting from the piezoelectric substrate 106 is a layer based on silicon oxide, or silicon nitride SisN4 or a combination of nitride and silicon oxide SiO x N y .
• the plurality 112 of sub-layers 114 can be a superposition of a layer of silicon oxide and a layer of SisN4 silicon nitride.
• the deposition of the polymer layer 104 is done on the upper layer 116 of the plurality 112 of sub-layers 114.
• the upper layer 116 is sandwiched between the polymer layer 104 and the rest of the sub-layers 114 of the plurality 112 of sub-layers 114 of the piezoelectric substrate 106.
• the assembly of the piezoelectric substrate 106 on the manipulation substrate 100 is made at the interface 136 between the free surface 102 of the manipulation substrate 100 and the polymer layer 104 formed on the upper layer 116 of the piezoelectric substrate 106.
• the upper layer 116 is sandwiched between the polymer layer 104 of the manipulation substrate and the rest of the sub-layers 114 of the plurality 112 of sub-layers 114 of the piezoelectric substrate 106 to form the heterostructure 134 which becomes after the step VI) the donor substrate 138.
• a surface activation treatment 118 can be carried out as in the method described with respect to FIG. 1a.
• the plasma treatment 118 is performed on the free surface 122 of the upper layer 116 of the plurality 112 of sub-layers 114.
• FIG. 2 schematically represents a method of manufacturing a donor substrate for transferring a piezoelectric layer onto a support substrate according to a variant of the first embodiment of the invention.
• the method illustrated in Figure 2 comprises, after step VI) illustrated in Figure 1a, a step VII) of thinning the piezoelectric substrate 106 of the donor substrate 128 obtained according to the method of the first embodiment and its first variant.
• the donor substrate 138 could be used.
• the thinning step VII) can be carried out by a grinding process or else by a chemical etching process of the piezoelectric substrate 106 to reduce the thickness ti of the substrate of piezoelectric material 106 of the donor substrate 128 to obtain either a piezoelectric substrate thinned 140 with a thickness t less than ti, ie a piezoelectric layer 140 with a thickness t2 of the order of 20 ⁇ m, or else between 5 ⁇ m and 25 ⁇ m.
• a treatment of the free surface 142 of the piezoelectric layer 140 obtained can be carried out once the thinning step VII) has been completed to improve the quality of the free surface 142 of the piezoelectric layer 140.
• FIG. 3 illustrates the second embodiment of the invention in which the step of depositing the polymer layer 154 is carried out on the manipulation substrate 100, instead of being carried out on the piezoelectric substrate 106. All the other steps I, II, III and V to VII are the same as in the first embodiment and its variants. All the characteristics common with the first embodiment and its variants and using the same reference number as above will not be described again, but reference is made to their detailed description above.
• step IV) of depositing the polymer layer 154 the polymer layer 154 is deposited directly in contact with the free surface 102 of the handling substrate 100.
• the handling substrate 100 can first be subjected to one or more steps of cleaning, brushing or polishing its free surface 102 to reduce the presence of particles or dust before depositing the polymer layer 154.
• the polymer layer 154 of the handling substrate 100 is placed in direct contact with the intermediate layer 108 of the piezoelectric substrate 106.
• the contact interface 126 between the polymer layer 154 and the intermediate layer 108 of the substrate piezoelectric 106 also has better adhesion. Indeed, in the same way as previously described, it is possible to choose an intermediate layer 108 which exhibits good adhesion to the piezoelectric substrate 106 as well as to the polymer layer 154.
• the contact interface 126 between the piezoelectric substrate 106 and the polymer layer 154 via the intermediate layer 108 is consolidated/reinforced and results in an improved mechanical stability of the donor substrate 124 compared to the state of the art.
• FIG. 4 schematically represents a method for transferring a piezoelectric layer according to a second embodiment of the invention using the donor substrate 144.
• the method can be carried out with the donor substrate 128, 138 obtained according to the other variants described in relation to Figures 1a, 1b or 2.
• the donor substrate 144 and a support substrate 156 are provided.
• the support substrate 156 can be a solid substrate based on silicon, sapphire, aluminum nitride (AIN), silicon carbide (SiC) or even gallium arsenide (GaAs).
• Support substrate 156 can be a crystalline or polycrystalline substrate.
• the donor substrate 144 exhibits a mechanical stability which allows it to be used in the process of transferring the piezoelectric layer 152 onto the support substrate 156.
• support substrate 156 may comprise a dielectric layer 158 previously formed on free surface 160 of support substrate 156, for example by centrifuge deposition or by a deposition technique such as plasma or evaporation deposition or thermal growth.
• the dielectric layer 158 is for example a layer of silicon oxide, a layer of silicon nitride SisN ⁇ or a layer comprising a combination of nitride and silicon oxide also called silicon oxynitride SiO x N y , or a superposition an oxide layer and a nitride layer.
• the formation of the dielectric layer 158 can be followed by a heat treatment to improve the adhesion of the dielectric layer 158 to the support substrate 156.
• a surface treatment to improve the quality of the surface of the dielectric layer 158 formed can also be achieved.
• the dielectric layer 158 can also be a layer of natural oxide which is formed on the free surface 160 of the support substrate 156.
• the support substrate 156 is provided without a dielectric layer 158 and/or without a natural oxide layer.
• a dielectric layer may be provided on piezoelectric layer 140 of donor substrate 144 instead of or in addition to dielectric layer 158 formed on support substrate 156.
• support substrate 156 may also include other layers.
• layers to produce a Bragg mirror or a trapping layer may/may be present on the support substrate 156.
• a trapping layer of polycrystalline, amorphous or porous silicon type may be present, thickness varying between 500nm and 5pm.
• a step B) of forming a zone of weakness 146 in the piezoelectric layer 140 of the donor substrate 144 is carried out so as to delimit the piezoelectric layer 152 to be transferred from the remainder 162 of the piezoelectric layer 140.
• This step of forming an embrittlement zone 140 is carried out by an implantation 150 of atomic or ionic species in the piezoelectric layer 140 of the donor substrate 144.
• the atomic or ion implantation 150 is carried out in such a way that the embrittlement zone 140 is located inside the piezoelectric layer 140 and separates a piezoelectric layer 152 from the rest 162 of the piezoelectric layer 140.
• the atomic or ionic species are implanted at a determined depth of the piezoelectric layer 140 which determines the thickness of the piezoelectric layer 152 to be transferred and the thickness t4 of the rest 148 of the piezoelectric layer 140.
• the thickness is typically between 50 nm and 1 ⁇ m, in particular around 600 nm.
• a dielectric layer can be formed on the piezoelectric layer 140 obtained from the donor substrate 144.
• This dielectric layer is for example a layer of silicon oxide, a layer of silicon nitride SisN4, or even a layer comprising a combination of nitride and silicon oxide also called silicon oxynitride SiO x N y , or a superposition of an oxide layer and a nitride layer.
• the formation of this dielectric layer can be followed by a heat treatment to improve the adhesion of the dielectric layer to the piezoelectric layer 140.
• a surface treatment to improve the quality of the surface of this formed dielectric layer can also be carried out, in particular after the implantation step 150 and before step C) mentioned below.
• the donor substrate 144 is assembled with the support substrate 156 to obtain a support substrate-donor substrate 170 assembly.
• the assembly 170 of the donor substrate 144 with the support substrate 156 is made at the level of the dielectric layer 158, such that the piezoelectric layer 140 of the donor substrate 144 is in direct contact with the dielectric layer 158 and the piezoelectric layer 152 to be transferred is sandwiched between the support substrate 156 and the remainder 162 of the donor substrate 144.
• the assembly 170 of the donor substrate 144 with the support substrate 156 takes place between the dielectric layer 158 and a dielectric layer formed on the donor substrate 144 as mentioned above.
• the assembly is done by molecular adhesion between the two substrates, at the piezoelectric interface - support substrate in a known manner.
• a step D) of fracturing along the zone of weakness 140 of the donor substrate 144 is carried out by supplying thermal and/or mechanical energy to separate the piezoelectric layer 152 from the remainder 162 of the donor substrate 144.
• the POI substrate 174 comprising the support substrate 156, the dielectric layer 158 and the piezoelectric layer 152 transferred is obtained.
• the use of the donor substrate 144 manufactured according to the invention allows the manufacture of a POI substrate 174 with a better yield.

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• 2022
  • 2022-01-17 FR FR2200380A patent/FR3131979B1/fr active Active
  • 2022-12-22 TW TW111149570A patent/TW202336927A/zh unknown
• 2023
  • 2023-01-11 EP EP23700213.4A patent/EP4466729A1/fr active Pending
  • 2023-01-11 US US18/728,998 patent/US20250176430A1/en active Pending
  • 2023-01-11 KR KR1020247027493A patent/KR20240135830A/ko active Pending
  • 2023-01-11 WO PCT/EP2023/050571 patent/WO2023135181A1/fr not_active Ceased
  • 2023-01-11 JP JP2024539002A patent/JP2025500549A/ja active Pending
  • 2023-01-11 CN CN202380016873.9A patent/CN118525353A/zh active Pending

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