Patent EP-2637197-A1 (EP)
Inventor: LEDUC PATRICK
IPC: H01L21/18
Filed: 2013-03-04
Abstract: The method comprises forming a first porous layer (104) on a face of a first element (102), forming a first bonding layer (106) on the first porous layer, and soldering by direct bonding of a second element (202) with the first bonding layer. The first porous layer comprises a voluminal level of porosities of >= 10% and/or is made of a elastically deformable material with a Young modulus of = 20 GPa and/or a elastically deformable material with an elastic limit of = 350 MPa. A size of pores of the first porous layer is lower than or equal to a tenth thickness of the first porous layer. The method comprises forming a first compressible porous layer (104) on a face of a first element (102), forming a first bonding layer (106) on the first porous layer, and soldering by direct bonding of a second element (202) with the first bonding layer. The first porous layer comprises a voluminal level of porosities of >= 10% and/or is made of a elastically deformable material having a Young modulus of = 20 GPa and/or a elastically deformable material having an elastic limit of = 350 MPa. A size of pores of the first porous layer is lower than or equal to a tenth thickness of the first porous layer and/or less than a size of particles to be present at an interface in the bonding between the two elements at the time of the soldering by direct bonding. The first element and/or the second element comprise a substrate or an electronic chip. The method further comprises: forming a second compressible porous layer (204) on a face of the second element; forming a second bonding layer on the second porous layer; engraving a position of a connection stud, the first porous layer and part of the first element through the first bonding layer by photolithography between the step of formation of the first bonding layer and the step of soldering by direct bonding of the second element with the first bonding layer; depositing a electrically conducting material forming the connection stud in the position; performing chemical and mechanical planarization on the first bonding layer; and depositing a material layer to form a barrier with the diffusion of material of the connection stud prior to depositing the electrically conducting material in the position, where the electrically conducting material is then deposited on the barrier material layer. The soldering by direct bonding of the second member with the first bonding layer is obtained by a direct contacting of the first bonding layer against the second bonding layer. The second porous layer comprises a voluminal level of porosities of >= 10%, and/or is made of an elastically deformable material having a Young modulus of = 20 GPa and/or of an elastically deformable material having an elastic limit of = 350 MPa. The first porous layer comprises a thickness higher than a thickness of the first bonding layer, and/or the second porous layer comprises a thickness higher than the thickness of the second bonding layer. The formation of the first porous layer and/or the formation of the second porous layer comprise: an application of carbon doped silicon oxides deposited by a porous plasma-enhanced chemical vapor deposition; depositing a material to be engraved and intended to form the first porous layer and/or the second porous layer and then forming pores by chemical engraving and/or electrochemical material deposition; and depositing material of the first porous layer and/or the second porous layer by blowing pore-forming particles added to the deposited material, and removing the pore-forming particles after forming the pores within the material of the first porous layer and/or the second porous layer. The formation of the first bonding layer and/or the formation of the second bonding layer comprises depositing a material of the first bonding layer on the first porous layer and/or depositing of a material of the second bonding layer on the second porous layer, and heat treating a part of the first porous layer and/or the second porous layer using plasma or chemical, where the treated part of the first porous layer forms the first bonding layer and/or the treated part of the second porous layer forms the second bonding layer. The connection stud formed in the first element is attached by direct bonding with a connection stud in the second element at the time of soldering by direct bonding of the second element with the first bonding layer.