Laser irradiation induced surface planarization of polycrystalline silicon films

Patent metadata

Field	Value
Publication number	US-10629434-B2
Application number	US-201615546914-A
Country	US
Kind code	B2
Filing date	Apr 8, 2016
Priority date	Apr 8, 2015
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

A method for planarizing excimer laser annealed (ELA) polycrystalline thin films via irradiation. The method includes providing an ELA thin film having an oxide and a top surface with a first surface roughness defined at least by a first plurality of protrusions. The ELA thin film is etched to substantially remove the oxide. At least a portion of the etched ELA thin film is then irradiated using a short-pulse duration excimer laser beam, to form an irradiated thin film with a second surface roughness defined at least by a second plurality of protrusions. The second surface roughness is lower than the first surface roughness.

First claim

What is claimed is:

1. A method, comprising:
providing a film comprising:
a polycrystalline thin film having a top surface having a first surface roughness and a first plurality of protrusions; and
an oxide layer over the top surface of the thin film;

etching the film to remove the oxide layer; and
irradiating a portion of the etched film using a short-pulse duration laser beam with controlled energy density to cause partial melting to the portion of the etched film, to form an irradiated polycrystalline thin film having a second surface roughness and a second plurality of protrusions wherein the second surface roughness is lower than the first surface roughness.

2. The method of claim 1 , wherein the film is an excimer laser annealed (ELA) film.

3. The method of claim 1 , wherein the portion of the etched film is irradiated using at least one of an excimer laser, a solid-state laser, a rapidly scanned continuous wave laser, and a rapidly scanned quasi-continuous wave laser that provides laser energy to cause partial melting to the polycrystalline thin film below the near complete melting threshold.

4. The method of claim 1 , wherein the irradiating comprises directing a single pulse of the laser beam toward the etched film.

5. The method of claim 1 , wherein the irradiating comprises directing a plurality of pulses of the laser beam toward the etched film.

6. The method of claim 1 , wherein the oxide layer is at least one of a deposited oxide and a native oxide.

7. The method of claim 1 , wherein the second surface roughness is at least 50% lower than the first surface roughness.

8. The method of claim 1 , wherein the second surface roughness is at least 10% lower than the first surface roughness.

9. The method of claim 1 , wherein the second surface roughness is lower than about 50 nm.

10. The method of claim 1 , wherein etching the film to remove the oxide layer comprises exposing the film to hydrofluoric acid (HF).

11. The method of claim 1 , wherein etching the film to remove the oxide layer comprises exposing the film to a plasma.

12. The method of claim 1 , wherein the excimer laser beam has a pulse width of no more than 200 ns.

13. A method, comprising:
providing a film comprising:
a polycrystalline thin film having a top surface having a first surface roughness and a first plurality of protrusions; and
an oxide layer over the top surface of the thin film;

etching the film to remove the oxide layer;
irradiating a portion of the film using a short-pulse duration laser beam with controlled energy density to cause partial melting to the portion of the etched film to form a self-leveling molten layer;
cooling the self-leveling molten layer; and
forming a modified thin film having a second surface roughness and a second plurality of protrusions wherein the second surface roughness is lower than the first surface roughness.

14. The method of claim 13 , wherein the film is an excimer laser annealed (ELA) film.

15. The method of claim 13 , wherein the excimer laser beam has a pulse duration of between 10 ns and 100 ns.

16. The method of claim 13 , wherein the portion of the etched film is irradiated using at least one of an excimer laser, a solid-state laser, a rapidly scanned continuous wave laser, and a rapidly scanned quasi-continuous wave laser that provides laser energy to cause partial melting to the polycrystalline thin film below the near complete melting threshold.

17. The method of claim 16 , wherein the oxide layer is at least one of a deposited oxide and a native oxide.

18. The method of claim 13 , wherein etching the film to remove the oxide layer comprises exposing the film to hydrofluoric acid (HF).

19. The method of claim 13 , wherein etching the film to remove the oxide layer comprises exposing the film to a plasma.

20. The method of claim 13 , wherein the modified thin film is a polycrystalline thin film.

Assignees

• Univ Columbia
• Im James S
• Yu Miao

Inventors

• Im James S
• Yu Miao

Classifications

• H10P95/04

  Planarisation of conductive or resistive materials · CPC title

• H10P70/277

  the processing being a planarisation of conductive layers · CPC title

• H10P50/00

  Etching of wafers, substrates or parts of devices · CPC title

• H10P14/3456

  Polycrystalline · CPC title

• H10P14/3451

  Structure · CPC title