METHOD TO FABRICATE AND TREAT A STRUCTURE OF SEMICONDUCTOR-ON-INSULATOR TYPE, ENABLING DISPLACEMENT OF DISLOCATIONS, AND CORRESPONDING STRUCTURE

1 . Method to fabricate and treat a structure of semiconductor-on-insulator type, successively comprising a carrier substrate ( 1 ), an oxide layer ( 3 ) and a thin layer ( 2 ) of semiconductor material, obtained by:

a) on said carrier substrate ( 1 ) bonding a donor substrate comprising said semiconductor layer ( 2 ), these substrates having identical crystal orientation;

b) thinning said donor substrate so as only to leave said thin layer ( 2 ),

one and/or the other of said carrier substrate ( 1 ) and thin layer ( 2 ) being coated with an oxide layer ( 3 );

each of said carrier substrate ( 1 ) and thin layer ( 2 ), in a plane parallel to their interface, respectively having a first and a second crystal lattice (R 1 , R 2 );

according to which:

1) a mask ( 4 ) is formed on said thin layer ( 2 ), so as to define exposed regions ( 20 ) on the surface of said layer, that are not covered by the mask ( 4 ) and are distributed in a desired pattern;

2) heat treatment is applied under a controlled neutral or reducing atmosphere, and under controlled time and temperature conditions, so as to urge at least part of the oxygen of the oxide layer ( 3 ) to diffuse through the thin layer ( 2 ), leading to controlled removal of the oxide in the regions ( 30 ) of the oxide layer ( 3 ) corresponding to the said desired pattern,

and characterized by the fact that:

at step a), said carrier substrate ( 1 ) and thin layer ( 2 ) are arranged relative to each other so that said crystal lattices, between them and along said plane (P) parallel to their interface (I), form an angle (α) called a “twist angle” of no more than 1°, and in a plane perpendicular to their interface (I) an angle (β) called a “tilt angle” of no more than 1°.

a thin layer ( 2 ) is used whose thickness is less than 1100 Angströms.

2 . Method according to claim 1 , characterized by the fact that at step a), said carrier substrate ( 1 ) and thin layer ( 2 ) are arranged so that said crystal lattices (R 1 , R 2 ) , in said plane parallel to their interface (I), together form a so-called “twist angle” of no more than 0.5°.

3 . Method according to any of the preceding claims, characterized by the fact that at step a), a carrier substrate ( 1 ) and a donor substrate are used which each carry a visual mark ( 10 ) oriented in a determined direction with respect to said crystal lattices (R 1 , R 2 ).

4 . Method according to any of the preceding claims, characterized by the fact that a thin layer ( 2 ) is used whose thickness is less than 800 Angströms.

5 . Method according to any of the preceding claims, characterized by the fact that at step b), said donor substrate is treated so as only to leave said thin layer ( 2 ) by fracture of the donor substrate along a previously formed stress region.

6 . Method according to any of claims 1 to 5 , characterized by the fact that at step b) said donor substrate is treated by reducing its thickness via its rear face, so as only to leave said thin layer ( 2 ).

7 . Method according to any of the preceding claims, characterized by the fact that a carrier substrate ( 1 ) in silicon is used.

8 . Method according to any of the preceding claims, characterized by the fact that a thin layer ( 2 ) particularly in silicon oxide is used, having a thickness of between 100 and 200 Angströms.

9 . Structure of semiconductor type which comprises a carrier substrate ( 1 ) and a thin layer ( 2 ) of a semiconductor material, characterized by the fact that:

said thin layer ( 2 ) comprises regions ( 31 ) of buried oxide ( 3 ), so that there are first regions in which said thin layer ( 2 ) is carried by the regions ( 31 ) of buried oxide ( 3 ), and there are second regions in which said thin layer ( 2 ) is carried by the carrier substrate ( 1 );

the material of said thin layer ( 2 ) located on said regions ( 31 ) of oxide ( 3 ) and also the material of said carrier substrate ( 1 ) located on these regions ( 31 ) have crystal lattices which, in a plane (P) parallel to their interface (I), together form an angle (α) called a “twist angle” of no more than 1° and, in a plane perpendicular to their interface (I), an angle (β) called a “tilt angle” of no more than 1;

the material of said thin layer ( 2 ) located between the regions ( 31 ) of oxide ( 3 ) and directly in contact with the carrier substrate ( 1 ) have the same crystal lattice orientation as the material of this carrier substrate ( 1 ).

10 . Structure according to claim 9 , characterized by the fact that it has dislocations on the periphery of the second regions i.e. where the thin layer ( 2 ) carried by the carrier substrate ( 1 ) is in contact with the regions ( 31 ) of buried oxide ( 3 ).

11 . Structure according to claim 9 or 10 , characterized by the fact that said thin layer has a thickness of less than 1100 Angströms.

12 . Structure according to any of claims 9 to 11 , characterized by the fact that the thickness of buried oxide ( 3 ) lies between 10 and 20 nanometres.

13 . Structure according to any of claims 9 to 12 , characterized by the fact that the carrier substrate ( 1 ) is in silicon {1,0,0}.