PROCESS FOR MANUFACTURING A STRUCTURE COMPRISING A GERMANIUM LAYER ON A SUBSTRATE

1 . Process for manufacturing a structure comprising a germanium layer ( 3 ) on a support substrate ( 1 ), characterised in that it comprises the following steps:

(a) formation of an intermediate structure ( 10 ) comprising said support substrate ( 1 ), a silicon oxide layer ( 20 ) and said germanium layer ( 3 ), the silicon oxide layer ( 20 ) being in direct contact with the germanium layer ( 3 ),

(b) application to said intermediate structure ( 10 ) of a heat treatment, in a neutral or reducing atmosphere, at a defined temperature and for a defined time, to diffuse at least part of the oxygen from the silicon oxide layer ( 20 ) through the germanium layer ( 3 ).

2 . Process according to claim 1 , characterised in that the heat treatment in step (b) is performed at a temperature between 800 and 900° C.

3 . Process according to any of claim 1 or 2 , characterised in that the oxygen content in the atmosphere of the treatment in step (b) is less than 1 ppm.

4 . Process according to any of claims 1 to 3 , characterised in that the thickness of the germanium layer ( 3 ) is less than 500 nm, preferentially less than 100 nm.

5 . Process according to any of claims 1 to 4 , characterised in that the thickness of the silicon oxide layer ( 20 ) of the intermediate structure ( 10 ) is less than 6 nanometres, preferentially less than 2 nm, and, in step (b), all the oxygen from said layer ( 20 ) diffuses through the germanium layer ( 3 ).

6 . Process according to any of claims 1 to 5 , characterised in that step (a) comprises the following steps:

i) formation of the silicon oxide layer ( 20 ) on the support substrate ( 1 ) or on a germanium donor substrate ( 30 ),

ii) formation of an embrittlement zone ( 31 ) in a germanium donor substrate ( 31 ), the embrittlement zone defining the germanium layer ( 3 ) to be transferred,

iii) bonding of the germanium donor substrate ( 30 ) on the support substrate ( 1 ), the silicon oxide layer ( 20 ) being situated at the bonding interface,

iv) rupture of the germanium donor substrate ( 30 ) along the embrittlement zone ( 31 ) and transfer of the germanium layer ( 3 ) onto the support substrate ( 1 ), so as to form said intermediate structure ( 10 ).

7 . Process according to any of claims 1 to 5 , characterised in that step (a) comprises the following steps:

i) formation of the silicon oxide layer ( 20 ) on the support substrate ( 1 ) or on a germanium donor substrate ( 30 ),

ii) bonding of the germanium donor substrate ( 30 ) on the support substrate ( 1 ), the silicon oxide layer ( 20 ) being situated at the bonding interface,

iii) thinning of the germanium donor substrate ( 30 ) so as to retain only the thickness of the germanium layer ( 3 ), thus forming said intermediate structure ( 10 ).

8 . Process according to any of claims 1 to 5 , characterised in that step (a) comprises the following steps:

i) formation of a silicon on insulator type structure ( 50 ), comprising the support substrate ( 1 ), a silicon oxide layer ( 20 ) and a silicon layer ( 40 ),

ii) deposition, on the silicon layer ( 40 ) of a SiGe layer ( 5 ),

iii) application of an oxidation heat treatment of said layer ( 5 ), resulting in the formation by condensation of a germanium layer ( 3 ) on the silicon oxide layer ( 20 ) and an upper silicon oxide layer ( 6 ) on said germanium layer ( 3 ),

iv) removal of the upper silicon oxide layer ( 6 ), so as to form said intermediate structure ( 10 ).

9 . Structure comprising a germanium layer ( 3 ) on a support substrate ( 1 ), characterised in that it comprises, between the support substrate ( 1 ) and the germanium layer ( 3 ), a silicon layer ( 4 ) in contact with the germanium layer ( 3 ), the silicon layer ( 4 ) having a thickness between 1 and 3 nanometres.

10 . Structure according to claim 9 , characterised in that it comprises, between the support substrate ( 1 ) and the silicon layer ( 4 ), a silicon oxide layer ( 2 ).