1 . Method for producing a connection structure comprising a conductor via and a contact zone with a metal and semi-conductor compound in the extension of said conductor via, the connection structure extending between an upper semi-conductor layer receiving an active zone of at least one higher level transistor of a microelectronic device comprising several levels of semi-conductor layers arranged one above the other and at least one conducting zone located under the upper level, the method comprising: a) supplying a lower stage provided with at least one first electronic component arranged at least partially in a lower semi-conductor layer resting on a substrate, the electronic component being surmounted by at least one insulating layer and by said conducting zone, then, b) transferring onto the lower stage an upper semi-conductor layer, then c) producing at least partially said transistor of which the active zone extends in the upper semi-conductor layer and at least one metal region in contact with the active zone, d) carrying out at least one thermal annealing in such a way as to form from said metal region, said contact zone with a metal and semi-conductor compound base and in contact with said upper semi-conductor layer, said contact zone being located in the extension of a conductor via formed before and/or after the transferring, said conductor via extending under the upper semi-conductor layer and being arranged in contact with said conducting zone.
2 . Method according to claim 1 , wherein the producing of the conductor via comprises, prior to the step b) of transferring: the formation through the insulating layer of a conducting element in contact with said conducting zone and said metal region in the extension of this conducting element, said metal region being flush on an upper face of the insulating layer, the transferring in the step b) being carried out in such a way that said metal region is put into contact with a lower face of the upper semi-conductor layer.
3 . Method according to claim 2 , wherein the formation of the conducting element and of said metal region in its extension comprises steps of: forming the conducting element passing through the insulating layer, removing an upper portion of the conducting element, in such a way as to release a hole in the insulating layer, filling said hole with at least one metal material is such a way as to produce said metal region.
4 . Method according to claim 1 , wherein the producing of the conductor via comprises, after the step b) of adding, steps of: forming of at least one opening passing through the upper semi-conductor layer, depositing of metal material in said opening in such a way as to form the metal region.
5 . Method according to claim 4 , wherein the producing of the conductor via comprises, prior to the step b) of transferring: the formation through the insulating layer of a conducting element in contact with said conducting zone then with said metal region in the extension of this conducting element, and wherein the adding in the step b) is carried out in such a way that an insulating thickness is retained above an upper end of said conducting element, said opening passing through the upper semi-conductor layer being formed in such a way as to furthermore pass through said insulating thickness and to expose said upper end of said conducting element.
6 . Method according to claim 5 , wherein at the step b) of transferring, the upper semi-conductor layer is coated with a first layer of dielectric material, and wherein said lower stage is coated with a second layer of dielectric material, the transferring being carried out by molecular bonding of the first layer of dielectric material on the second layer of dielectric material.
7 . Method according to claim 4 , wherein the producing of the conductor via further comprises, after the production of said opening and the step d) of forming said contact zone with a metal and semi-conductor compound, the forming of a metal pad in said opening.
8 . Method according to claim 4 , the producing of the conductor via comprises after the production of said opening, the production of a metal pad in this opening, said metal region being a region of said metal pad in contact with the upper semi-conductor layer.
9 . Method according to claim 3 , wherein after the forming of said opening passing through the upper semi-conductor layer or of said hole in the insulating layer, a cleaning is carried out in said opening or in said hole prior to the depositing or the filling with metal material.
10 . Method according to claim 1 , wherein prior to the step d), at least one metal zone is further formed on an upper face of the upper semi-conductor layer, the annealing carried out in the step d) being carried out in such a way as to form concomitantly with the forming of said contact zone with a metal and semi-conductor compound, a compound region of metal and semi-conductor in the extension of said metal zone.
11 . Method according to claim 1 , wherein the source and drain regions of said transistor are doped in the step c), with the thermal annealing in the step d) being provided in such a way as to carry out an activation of doping agents of the source and drain regions.
12 . Method according to claim 1 , wherein the thermal annealing carried out in the step d) is a laser annealing.
13 . Method according to claim 1 , wherein said metal region is in contact with another active zone of another transistor, in such a way that said contact zone formed in the step d) with a metal and semi-conductor compound base is in contact with said other active zone.
14 . Method according to claim 1 , wherein the semi-conductor layer is made of silicon and wherein the metal region has a cobalt and/or Ti and/or Ni base.
15 . Method for producing a connection structure comprising a conductor via and a contact zone with a metal and semi-conductor compound in the extension of said conductor via, the connection structure extending between an upper semi-conductor layer receiving an active zone of at least one higher level transistor of a microelectronic device comprising several levels of semi-conductor layers arranged one above the other and at least one conducting zone located under the upper level, the method comprising: a) supplying a lower stage provided with at least one first electronic component arranged at least partially in a lower semi-conductor layer resting on a substrate, the electronic component being surmounted by at least one insulating layer and by said conducting zone, then, b) transferring onto the lower stage an upper monocrystalline semi-conductor layer, on an upper face of the at least one insulating layer, then c) producing at least partially said transistor of which the active zone extends in the upper semi-conductor layer and at least one metal region in contact with the active zone, d) carrying out at least one thermal annealing in such a way as to form from said metal region, said contact zone with a metal and semi-conductor compound base and in contact with said upper semi-conductor layer, said contact zone being located in the extension of a conductor via formed before the transferring, said conductor via extending under the upper semi-conductor layer and being arranged in contact with said conducting zone.
16 . Method according to claim 15 , wherein the producing of the conductor via comprises: the formation through the insulating layer of a conducting element in contact with said conducting zone and said metal region in the extension of this conducting element, said metal region being flush on an upper face of the insulating layer, the transferring in the step b) being carried out in such a way that said metal region is put into contact with a lower face of the upper semi-conductor layer.
17 . Method according to claim 16 , wherein the formation of the conducting element and of said metal region in its extension comprises steps of: forming the conducting element passing through the insulating layer, removing an upper portion of the conducting element, in such a way as to release a hole in the insulating layer, filling said hole with at least one metal material is such a way as to produce said metal region.
18 . Method for producing a connection structure comprising a conductor via and a contact zone with a metal and semi-conductor compound in the extension of said conductor via, the connection structure extending between an upper semi-conductor layer receiving an active zone of at least one higher level transistor of a microelectronic device comprising several levels of semi-conductor layers arranged one above the other and at least one conducting zone located under the upper level, the method comprising: a) supplying a lower stage provided with at least one first electronic component arranged at least partially in a lower semi-conductor layer resting on a substrate, the electronic component being surmounted by at least one insulating layer and by said conducting zone, then, b) transferring onto the lower stage an upper monocrystalline semi-conductor layer on an upper face of the at least one insulating layer, then c) producing at least partially said transistor of which the active zone extends in the upper semi-conductor layer and at least one metal region in contact with the active zone, d) carrying out at least one thermal annealing in such a way as to form from said metal region, said contact zone with a metal and semi-conductor compound base and in contact with said upper semi-conductor layer, said contact zone being located in the extension of a conductor via formed after the transferring, said conductor via extending under the upper semi-conductor layer and being arranged in contact with said conducting zone.
19 . Method according to claim 18 , wherein the producing of the conductor via comprises, steps of: forming of at least one opening passing through the upper semi-conductor layer, depositing of metal material in said opening in such a way as to form the metal region.
20 . Method according to claim 19 , wherein the producing of the conductor via comprises, prior to the step b) of transferring: the formation through the insulating layer of a conducting element in contact with said conducting zone then with said metal region in the extension of this conducting element, and wherein the adding in the step b) is carried out in such a way that an insulating thickness is retained above an upper end of said conducting element, said opening passing through the upper semi-conductor layer being formed in such a way as to furthermore pass through said insulating thickness and to expose said upper end of said conducting element.
