Method for making a stacked structure comprising a thin film adhering to a target substrate

• US 20040014299A1
• Filed: 04/30/2003
• Published: 01/22/2004
• Est. Priority Date: 11/06/2000
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Letertre, fabrice, Aspar, Bernard, Moriceau, Hubert, Jalaguier, Eric
• Granted Patent: US 6,974,759 B2
• Time in Patent Office: Days
• US Class Current: 438/459
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: H01L 21/76256 using silicon etch back techniques, e.g. BESOI, ELTRAN

Abstract

The invention relates to a process for manufacturing a stacked structure comprising at least one thin layer bonding to a target substrate, comprising the following steps:

a) formation of a thin layer starting from an initial substrate, the thin layer having a free face called the first contact face,

b) putting the first contact face into bonding contact with a face of an intermediate support, the structure obtained being compatible with later thinning of the initial substrate,

c) thinning of the said initial substrate to expose a free face of the thin layer called the second contact face and opposite the first contact face,

d) putting a face of the target substrate into bonding contact with at least part of the second contact face, the structure obtained being compatible with later removal of all or some of the intermediate support,

e) removal of at least part of the intermediate support in order to obtain the said stacked structure.

Claims

1. Process for manufacturing a stacked structure comprising at least one thin layer bonded to a target substrate (15), comprising the following steps:

a) formation of a thin layer (7) starting from an initial substrate (1), the thin layer (7) having a free face called the first contact face (8),

b) putting the first contact face into bonding contact (8) with a face (11) of an intermediate support (10), the structure obtained being compatible with later thinning of the initial substrate,

c) thinning of the said initial substrate (1) to expose a free face of the thin layer called the second contact face (14) and opposite the first contact face (8),

d) putting a face of a target substrate (15) into bonding contact with at least part of the second contact face (14), the structure obtained being compatible with later removal of all or some of the intermediate support,

e) removal of at least part of the intermediate support (10) in order to obtain the said stacked structure.

2. Process according to claim 1, characterized in that the target substrate is only a temporary support for the thin layer, the said steps in the process being entirely or partly repeated, the target substrate being treated as the initial substrate or the intermediate support.

3. Process according to claim 1, characterized in that the compatibility of the said structure is obtained in step b) and/or in step d) by forming a thin layer in step a) so as to avoid bonding defects while thinning in step c) and during removal in step e), respectively.

4. Process according to claim 3, characterized in that the said compatibility is the result of the thickness given to the thin layer and/or the material or materials making up the said thin layer.

5. Process according to claim 3, characterized in that the nature of the intermediate support and/or the target substrate in contact with the thin layer, is chosen so as to avoid incompatibility related to a phase change of the materials of the structure obtained.

6. Process according to claim 3, characterized in that the nature of the intermediate support and/or the target substrate in contact with the thin layer, is chosen so as to avoid incompatibility related to non-uniformity of the materials in the structure obtained.

7. Process according to claim 3, characterized in that the nature of the intermediate support and/or the target substrate in contact with the thin layer is chosen so as to avoid incompatibility related to a difference between the coefficients of thermal expansion of the intermediate support and/or the target substrate, and the thin layer.

8. Process according to claim 3, characterized in that the thin layer and/or the intermediate support and/or the target substrate comprise(s) at least one additional layer with one or more contact faces.

9. Process according to claim 8, characterized in that the additional layer before step d) is provided with all or part of at least one component.

10. Process according to claim 8, characterized in that the additional layer is composed of an oxide or polycrystalline silicon or amorphous silicon.

11. Process according to claim 1, characterized in that steps a) and c) are such that the roughness of the first contact face of the thin layer and/or the intermediate support is less than the roughness of its second contact face and/or the target substrate, the compatibility of the structure in step d) being obtained by putting the second contact face into bonding contact with the thin layer and by removal of the intermediate support.

12. Process according to claim 3, characterized in that the bonding contact of the first contact face and/or the second contact face of the thin layer enabling the said compatibility in step b) and/or in step d) is a result of the use of a treatment enabling bonding contact.

13. Process according to claim 12, characterized in that the treatment used for bonding contact is chosen alone or in combination among the treatments including mechanical-chemical and/or ionic polishing, insertion of an intermediate layer between a contact face of the thin layer and the corresponding intermediate support or the target substrate, heat treatment and chemical treatment.

14. Process according to claim 1, characterized in that the bonding contact in step b) and/or step d) is achieved by molecular bonding.

15. Process according to claim 1, characterized in that the surface polarity of the first contact face of the thin layer (polarity related to the nature of the atoms on this surface) is different from the polarity of its second contact face, the compatibility of the structure in step d) being obtained by putting the second contact face of the thin layer and the target substrate into bonding contact, and due to the removal of the intermediate support of the first contact face of the thin layer that thus becomes a free face.

16. Process according to claim 1, characterized in that the structure compatibility achieved in step d) is obtained by creating a bonding contact of the second contact face of the thin layer with the target substrate with a bonding energy that enables removal of the target substrate after step e).

17. Process according to claim 1, characterized in that an intermediate step will be carried out between step c) and step d), consisting of making elements in the second contact face of the thin layer and/or the target substrate, the structure obtained after step d) being compatible with the presence of the said elements.

18. Process according to claim 1, characterized in that an intermediate step is performed before step d), consisting of a trimming operation in order to isolate at least one area of the second contact face, step d) putting at least one of these areas into bonding contact with the target substrate.

19. Process according to claim 1, characterized in that the step a) is done starting from a substrate (1) covered by at least one layer of material (3).

20. Process according to claim 19, characterized in that after step e), the process comprises a step consisting of eliminating the layer of material (3) covering the substrate (1) in step a).

21. Process according to any one of claims 19 or 20, characterized in that the initial substrate (1) is made of silicon, and the layer of material (3) that covers it is made of silicon oxide.

22. Process according to claim 1, characterized in that:

step a) includes the introduction of gaseous compounds into the initial substrate (1) through one (2) of its faces corresponding to the first said contact face (8), to form a weakened layer (5) separating the said film (6) from the rest (9) of the initial substrate and possibly leading to a fracture of the initial substrate during step c),

step c) consists of making a preferred treatment to obtain the fracture in the initial substrate (1) at the weakened layer (5).

23. Process according to claim 1, characterized in that at least part of the intermediate support is removed by the introduction of gaseous compounds either through the thin layer after creating a contact, or through the contact face of the intermediate support before or after putting it into bonding contact with the first contact face of the thin layer, this addition of gaseous compounds forming a weakened layer enabling the removal of all or part of the intermediate support.

24. Process according to claim 1, characterized in that the stacked structure obtained at the end of step e) is thinned on the side of the first contact face.

25. Process according to claim 1, characterized in that it uses an initial substrate made of monocrystalline silicon, an intermediate support made of monocrystalline silicon, a target substrate made of polycrystalline or monocrystalline silicon of lower quality than the silicon in the initial substrate.

26. Process according to claim 1, characterized in that it uses an SiC or GaAs initial substrate, an SiC or GaAs intermediate support, an SiC or GaAs target substrate with a lower quality than the initial substrate material, the thin layer containing SiC or GaAs originating from the initial substrate.

27. Process according to claim 1, characterized in that the thin layer is a layer of a material from Si, GaN, SiC, LiNbO₃, Ge, GaAS, InP, sapphire and semiconductors.