US-12617194-B2 - Method of manufacturing a multilayer structure

US12617194B2US 12617194 B2US12617194 B2US 12617194B2US-12617194-B2

Abstract

A method for producing a multilayer structure includes the following steps: a) providing a first substrate, b) depositing a thick layer of a precursor formulation including a preceramic polymer filled with inorganic particles on the first substrate, c) providing a second substrate, d) adhesively bonding the thick layer and the second substrate, e) thinning the first substrate or the second substrate so as to obtain an active layer, f) applying a pyrolysis heat treatment so as to ceramize the preceramic polymer of the thick layer and to obtain a ceramic matrix composite material, the filler content and the nature of the inorganic particles being chosen so that the thick layer has a coefficient of thermal expansion which differs, at most, by 15% from that of the first substrate and from that of the second substrate.

Inventors

Marilyne ROUMANIE
Christelle Navone
Sébastien QUENARD
Didier Landru
Christelle Veytizou

Assignees

Commissariat à l'Energie Atomique et aux Energies Alternatives
SOITEC

Dates

Publication Date: 20260505
Application Date: 20220412
Priority Date: 20210416

Claims (12)

1 . A method for producing a multilayer structure intended for applications in the field of microelectronics, the method comprising the following steps: a) providing a first substrate, b) depositing a thick layer of a precursor formulation comprising a preceramic polymer charged with inorganic particles over the first substrate, c) providing a second substrate, d) bonding the thick layer and the second substrate, e) thinning the first substrate or the second substrate so as to obtain an active layer, f) applying a pyrolysis heat treatment so as to ceramize the preceramic polymer of the thick layer and obtain a ceramic matrix composite material, the charge rate and the nature of the inorganic particles being selected so that the thick layer has a coefficient of thermal expansion which differs, at most, by 15% from that of the first substrate and that of the second substrate, between room temperature and the pyrolysis temperature.
2 . The method for producing a multilayer structure according to claim 1 , wherein the bonding of step d) between the thick layer and the second substrate is carried out via an adhesion primer layer, formed beforehand over the second substrate and/or over the thick layer.
3 . The method for producing a multilayer structure according to claim 1 , wherein the bonding of step d) comprises a step of bringing the thick layer and the second substrate into contact so as to form a stack and a step i) of hot pressing the stack.
4 . The method for producing a multilayer structure according to claim 1 , wherein the precursor formulation comprises a charge rate of inorganic particles in a range from 50% to 80% by volume with respect to the volume of the preceramic polymer.
5 . The method for producing a multilayer structure according to claim 1 , wherein the inorganic particles are selected from Si 3 N 4 , SiC, AlN, Al 2 O 3 and a mixture of these inorganic particles.
6 . The method for producing a multilayer structure according to claim 1 , wherein the preceramic polymer of the precursor formulation is selected from the group consisting of polysiloxanes, polycarbosilanes, polycarbosiloxanes polysilazanes, polysilsesquioxanes, polysilylcarbodiimides, polysilsesquicarbodiimides, polysilsesquiazane, polyborosilanes, polyborosiloxanes, polyborosilazanes, and a combination of these polymers.
7 . The method for producing a multilayer structure according to claim 1 , wherein step b) of depositing the thick layer is carried out by coating or screen-printing.
8 . The production method according to claim 1 , comprising before step b) a step a1) of implanting ionic species in the first substrate so as to create a weakening plane, and wherein the thinning step e) comprises a fracture along the weakening plane.
9 . The production method according to claim 8 , comprising after the implantation step a1), a step a2) of depositing a stiffening layer over the implanted first substrate.
10 . The method for producing a multilayer structure according to claim 1 , wherein the thinning step e) is carried out by rectification, so as to obtain a thickness of active layer ranging from 10 micrometers to 140 micrometers.
11 . A multilayer structure intended for applications in microelectronics, the multilayer structure comprising a thick layer disposed between an active layer and a support substrate consisting of one amongst a first substrate and a second substrate, the active layer originating from thinning of the other one amongst the first substrate and the second substrate, the thick layer comprising a composite material including a ceramic matrix and inorganic particles, the nature and the charge rate of inorganic particles being selected so that the thick layer has a CTE which differs at most by 15% from the CTE of the material of the support substrate and that of the active layer.
12 . An intermediate structure intended to form by pyrolysis the multilayer structure according to claim 11 , the intermediate structure comprising a thick layer disposed between an active layer and a support substrate consisting of one amongst a first substrate and a second substrate, the active layer originating from thinning of the other one amongst the first substrate and the second substrate, the thick layer comprising a preceramic polymer charged with inorganic particles, the nature and the charge rate of inorganic particles being selected so that the thick layer has a CTE which differs at most by 15% from the CTE of the material of the support substrate and that of the active layer between room temperature and a pyrolysis temperature of the preceramic polymer.

Description

The present invention relates to the field of producing advanced substrates for applications in electronics (for example for MEMS) in microelectronics, in optoelectronics (for example for LEDs), in power electronics, in RF, for packaging and transfer handles. In particular, the invention relates to a method for producing a multilayer structure, withstanding high temperatures, and in particular a structure of the SeOI type (standing for Semiconductor On Insulator) proposing a semiconductor layer separated from a support substrate by a thick layer with modular properties, for example for the integration of RF components. According to another aspect, the invention also relates to a multilayer structure obtained by said producing method. The current trend tends towards an increasingly dense integration of components and miniaturization of devices, which increases the need for substrates that feature improved performances, including in particular a very good heat dissipation capacity, as well as excellent resistance to temperature variations. The manufacture of increasingly more complex structures requires annealing at temperatures that could reach 1,000° C., not to mention that the operating temperature could reach 800° C., in particular with regards to RF applications. The different materials necessary to create these multilayer structures are at the origin of different expansions within the structure. This generates stresses that could lead to the apparition of defects, cracks within the layers or the delamination of the layers. These constraints exclude the use of traditional polymers, withstanding a maximum temperature of 400° C., to obtain bonding between the layers. One of the aims of the present invention is to provide a method for producing a multilayer structure which overcomes at least one of the abovementioned obstacles. To this end, the present invention provides a method for producing a multilayer structure intended for applications in the field of microelectronics, the method comprising the following steps: a) providing a first substrate,b) depositing a thick layer of a precursor formulation comprising a preceramic polymer charged with inorganic particles over the first substrate,c) providing a second substrate,d) bonding the thick layer and the second substrate,e) thinning the first substrate or the second substrate so as to obtain an active layer, intended in particular to receive electronic devices,f) applying a pyrolysis heat treatment so as to ceramize the preceramic polymer of the thick layer and obtain a ceramic matrix composite material,the charge rate and the nature of the inorganic particles being selected so that the thick layer has a coefficient of thermal expansion which differs at most by 15% from that of the first substrate and that of the second substrate between the room temperature and the pyrolysis temperature, advantageously which differs at most by 10% from that of the first substrate and that of the second substrate and for example which differs at most by 5% from that of the first substrate and that of the second substrate. Thus, the production method according to the invention allows obtaining a multilayer structure wherein the properties of the thick layer and in particular the coefficient of thermal expansion (also known by the acronym CTE standing for Coefficient of Thermal Expansion) can be modulated so as to be compatible with the CTEs of the first substrate and of the second substrate. Advantageously, the structure may be used in processes or applications involving considerable thermal changes. The existence of a large choice of preceramic polymer and inorganic particles ensures the possibility of selecting the polymer suited to the targeted multilayer structure, through its properties and its compatibility with the substrate over which it is deposited. In this case, the preceramic polymer and the inorganic particles are selected so that once crosslinked and pyrolyzed, the resulting composite material has a coefficient of thermal expansion close to that of the first and/or second support. Thus, the materials constituting the multilayer structure expand and contract in a similar way during temperature changes, which avoids stresses in the structure that might damage the layers by the apparition of cracks, defects, or delamination of the layers. Depending on the inorganic particles used, the thick layer may be electrically insulating while having a high heat dissipation capacity. This is particularly advantageous for regulating the temperature of the structure, in particular when used in applications comprising transistor-type components, the operating temperature of which could reach 800° C. Thus, the thick layer according to the invention allows for a great modularity. In addition, the preceramic polymer has the advantage of having an excellent temperature resistance. Indeed, a preceramic polymer is an organic/inorganic polymer that is generally used in order to make