Methods of laser marking semiconductor substrates
In one embodiment, methods for making semiconductor devices are disclosed.
1. A method comprising:
providing a semiconductor substrate comprising:
a base substrate having a first semiconductor material;
a buried structure; and
a device layer having a second semiconductor material, wherein the buried structure is disposed between the base substrate and the device layer; and
laser marking the semiconductor substrate,
wherein the buried structure has a thickness equal to about k×λ laser /(2×n), wherein:
λ laser is a wavelength of peak emission for the laser applied to mark the semiconductor substrate;
k is an integer greater than zero (1, 2, 3 . . . ); and
n is an index of refraction for the buried structure.
2. The method of claim 1 , wherein the base substrate is silicon, SiC, GaN, or sapphire.
3. The method of claim 1 , wherein the buried structure is an insulating material.
4. The method of claim 1 , wherein the buried structure is silicon dioxide, AlGaN, or AlN.
5. The method of claim 1 , wherein the device layer is silicon, SiC, GaN, or sapphire.
6. The method of claim 1 , wherein the device layer is monocrystalline.
7. The method of claim 1 , wherein the thickness of the buried structure is about 0.001 μm to about 5 μm.
8. The method of claim 1 , wherein a thickness of the device layer is about 0.1 μm to about 500 μm.
9. The method of claim 1 , wherein the wavelength of peak emission for the laser marking the semiconductor substrate is about 200 nm to about 1,500 nm.
10. The method of claim 1 , further comprising fabricating one or a plurality of integrated circuits in the semiconductor substrate.
11. The method of claim 10 , further comprising dicing the semiconductor substrate to obtain one or a plurality of semiconductor chips.
12. The method of claim 1 , wherein:
(i) the base substrate is silicon;
(ii) the buried structure is silicon dioxide; and
(iii) the device layer is monocrystalline silicon.
13. A method comprising:
receiving a semiconductor substrate comprising:
a base substrate having a first semiconductor material;
a buried structure; and
a device layer having a second semiconductor material, wherein the buried structure is disposed between the base substrate and the device layer;
determining a thickness of the buried structure;
selecting a wavelength of peak emission for laser marking the semiconductor substrate such that the wavelength of peak emission is approximately equal to (2×d×n)/k, wherein:
d is a thickness of the buried structure;
k is an integer greater than zero (1, 2, 3 . . . ); and
n is an index of refraction for the buried structure; and
laser marking the semiconductor substrate using the selected wavelength of peak emission.
14. The method of claim 13 , wherein selecting the wavelength of peak emission comprises tuning an output of the laser to the wavelength of peak emission.
15. The method of claim 14 , wherein tuning the output of the laser comprises utilizing an optical frequency multiplier.
16. The method of claim 13 , wherein selecting the wavelength of peak emission comprises selecting a laser for marking the semiconductor substrate from a plurality of lasers having different wavelengths of peak emission.
17. The method of claim 13 , wherein determining the thickness of the buried structure comprises receiving data that corresponds to the thickness of the buried structure.
18. An semiconductor substrate comprising:
a base substrate having a first semiconductor material;
a buried structure;
a device layer having a second semiconductor material, wherein the buried structure is disposed between the base substrate and the device layer; and
a laser marking formed in the semiconductor substrate by applying a laser having a wavelength of peak emission that is approximately equal to (2×d×n)/k, wherein:
d is a thickness of the buried structure;
k is an integer greater than zero (1, 2, 3 . . . ); and
n is an index of refraction for the buried structure.
19. The semiconductor substrate of claim 18 , wherein the laser marking comprises a pattern of uniformly-sized shapes.
20. The semiconductor substrate of claim 18 , wherein the semiconductor substrate further comprises an antireflective layer on the device layer, wherein the device layer is disposed between the antireflective layer and the buried structure.