Process, stack and assembly for separating a structure from a substrate by electromagnetic radiation

Patent metadata

Field	Value
Publication number	US-9679777-B2
Application number	US-201414909969-A
Country	US
Kind code	B2
Filing date	Aug 5, 2014
Priority date	Aug 8, 2013
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A method for separating a structure from a substrate through electromagnetic irradiations (EI) belonging to a spectral range comprises the steps of a) providing the substrate, b) forming an absorbent separation layer on the substrate, c) forming the structure to be separated on the separation layer, d) exposing the separation layer to the electromagnetic irradiations (EI) via the substrate such that the separation layer breaks down under the effect of the heat stemming from the absorption, the method being notable in that it comprises a step b1) of forming a transparent thermal barrier layer on the separation layer, the exposure period and the thickness of the thermal barrier layer being adapted such that the temperature of the structure to be separated remains below a threshold during the exposure period, beyond which threshold, faults are likely to appear in the structure.

First claim

The invention claimed is:

1. A method for separating a structure from a substrate through electromagnetic irradiations belonging to a spectral range, the separation method having the steps of:
a) providing the substrate, the substrate being transparent in the spectral range,
b) forming at least one separation layer on the substrate, the spectral range of the electromagnetic irradiations (EI) being adapted such that the separation layer(s) are absorbent in the spectral range,
c) forming the structure to be separated on the separation layer(s),
d) exposing the separation layer(s) to the electromagnetic irradiations via the substrate during an exposure period at a given power density such that the separation layer(s) break down under the effect of the heat stemming from the absorption of the electromagnetic irradiations, wherein the separation method being comprises a step b1) of forming a thermal barrier layer on the separation layer(s), the spectral range of the electromagnetic irradiations being adapted such that the thermal barrier layer is transparent in the spectral range, the exposure period and the thickness of the thermal barrier layer being adapted such that the temperature of the structure to be separated remains below a threshold temperature during the exposure period, beyond which threshold temperature, faults are likely to appear in the structure, step c) being executed such that the structure to be separated is formed on the thermal barrier layer.

2. The separation method according to claim 1 , wherein the electromagnetic irradiations are electromagnetic pulses, and wherein the exposure period and the thickness of the thermal barrier layer, which is denoted E 1 , have the following relationship: E 1 ≦√{square root over (2D 1 τ)}; where D 1 is the thermal diffusion coefficient of the thermal barrier layer and τ is the duration of an electromagnetic pulse of the electromagnetic pulses.

3. The separation method according to claim 1 , wherein the separation method further comprises a step a1) of forming an additional thermal barrier layer on the substrate, the spectral range of the electromagnetic irradiations being adapted such that the additional thermal barrier layer is transparent in the spectral range, the exposure period and the thickness of the additional thermal barrier layer being adapted such that the temperature of the substrate remains below a threshold temperature during the exposure period, beyond which threshold temperature, faults are likely to appear in the substrate, and wherein step b) is executed such that the separation layer(s) are formed on the additional thermal barrier layer.

4. The separation method according to claim 3 , wherein the electromagnetic irradiations are electromagnetic pulses, and wherein the exposure period and the thickness of the additional thermal barrier layer, which is denoted E 2 , have the following relationship: E 2 ≧√{square root over (2D 2 τ)}; where D 2 is the thermal diffusion coefficient of the additional thermal barrier layer and τ is the duration of an electromagnetic pulse of the electromagnetic pulses.

5. The separation method according to claim 3 , wherein the thermal barrier layer and the additional thermal barrier layer each have a thermal diffusion coefficient, and wherein the exposure period for the electromagnetic irradiations and the thermal diffusion coefficients are adapted such that the heat stemming from the absorption of the electromagnetic irradiations by the separation layer(s) is confined between the thermal barrier layer and the additional thermal barrier layer.

6. The separation method according to claim 3 , wherein the additional thermal barrier layer is comprises a material having a lattice parameter between the lattice parameter of the substrate and the lattice parameter of the separation layer(s).

7. The separation method according to claim 1 , wherein the thermal barrier layer comprises a material having a lattice parameter between the lattice parameter of the structure to be separated and the lattice parameter of the separation layer(s).

8. The separation method according to claim 1 , wherein the substrate comprises GaN, the separation layer(s) comprise In (x) Ga (1-x) N, wherein 0.10≦x≦0.20, and the thermal barrier layer and/or the additional thermal barrier layer comprises AlGaN, and the spectral range of the electromagnetic irradiations is between 400 and 450 nm.

9. The separation method according to claim 1 , wherein the substrate comprises InP, the separation layer(s) comprise In (x) Ga (1-x) As, the thermal barrier layer and/or the additional thermal barrier layer comprises InAlAs, and the spectral range of the electromagnetic irradiations is between 1000 and 3500 nm.

10. The separation method according to claim 1 , wherein step d) is executed by means of at least one laser emitting the electromagnetic irradiations that is associated with an optical parametric oscillator.

11. A stack for separating a structure from a substrate through electromagnetic irradiations belonging to a spectral range during an exposure period at a given power density, the separation stack comprising:
the substrate, wherein the substrate is transparent in the spectral range,
at least one separation layer disposed on the substrate, wherein the separation layer(s) being absorbent in the spectral range, the separation layer(s) being likely to break down under the effect of the heat stemming from the absorption of the electromagnetic irradiations, and
the structure to be separated disposed on the separation layer(s), wherein the separation stack it comprises a thermal barrier layer disposed between the separation layer(s) and the structure to be separated, and wherein the thermal barrier layer is transparent in the spectral range, the thermal barrier layer having a thickness that is adapted to the exposure period such that the temperature of the structure to be separated remains below a threshold temperature during the exposure period, beyond which threshold temperature, faults are likely to appear in said structure.

12. The separation stack according to claim 11 , wherein the electromagnetic irradiations are electromagnetic pulses, and wherein the thickness of the thermal barrier layer, which is denoted E 1 , has the following relationship: E 1 ≧√{square root over (2D 1 τ)}; where D 1 is the thermal diffusion coefficient of the thermal barrier layer and τ is the duration of an electromagnetic pulse of the electromagnetic pulses.

13. The separation stack according to claim 11 , wherein the separation stack comprises an additional thermal barrier layer disposed between the separation layer(s) and the substrate, the additional barrier layer being transparent in the spectral range, the additional thermal barrier layer having a thickness that is adapted to the exposure period such that the temperature of the substrate remains below a threshold temperature during the exposure period, beyond which threshold temperature, faults are likely to appear in the substrate.

14. The separation stack according to claim 13 , wherein the electromagnetic irradiations are electromagnetic pulses, and the thickness of the additional thermal barrier layer, which is denoted E 2 , has the following relationship: E 2 ≧√{square root over (2D 2 τ)}; where D 2 is the thermal diffusion coefficient of the additional thermal barrier layer and τ is the duration of an electromagnetic pulse of the electromagnetic pulses.

15. The separation stack according to claim 13 , wherein the thermal barrier layer and the additional thermal barrier layer each have a thermal diffusion coefficient, and the thermal

Assignees

• Soitec Silicon On Insulator

Inventors

• Sinquin Yann
• Bethoux Jean-Marc
• Kononchuk Oleg

Classifications

• H10P95/11

  Separation of active layers from substrates · CPC title

• H10P34/42 Primary

  with electromagnetic radiation, e.g. laser annealing (laser cutting H10P54/20) · CPC title

• H01L33/0079

  Electricity · mapped topic

• H01L29/20

  Electricity · mapped topic

• H01L21/268 Primary

  Electricity · mapped topic