CRYSTALLIZATION PROCESSING FOR SEMICONDUCTOR APPLICATIONS

• US 20110129959A1
• Filed: 11/23/2010
• Published: 06/02/2011
• Est. Priority Date: 11/30/2009
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Moffatt, Stephen
• Granted Patent: US 8,313,965 B2
• Time in Patent Office: Days
• US Class Current: 438/97
• CPC Class Codes: C30B 13/24 using electromagnetic waves
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02568 Chalcogenide semiconducting materials not being oxides, e.g. ternary compounds
• CPC Class Codes: H01L 21/02686 Pulsed laser beam
• CPC Class Codes: H01L 21/2636 for heating, e.g. electron beam heating
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 29/685 Hi-Lo semiconductor devices, e.g. memory devices
• CPC Class Codes: H01L 31/1872 Recrystallisation
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A method and apparatus for forming a crystalline semiconductor layer on a substrate are provided. A semiconductor layer is formed by vapor deposition. A pulsed laser melt/recrystallization process is performed to convert the semiconductor layer to a crystalline layer. Laser, or other electromagnetic radiation, pulses are formed into a pulse train and uniformly distributed over a treatment zone, and successive neighboring treatment zones are exposed to the pulse train to progressively convert the deposited material to crystalline material.

Claims

1. A method of reorganizing the structure of a solid material, comprising:

exposing the solid material to pulses of energy to progressively melt the solid material, forming a molten material; and

recrystallizing the molten material.

2. The method of claim 1, wherein recrystallizing the molten material comprises progressively crystallizing the molten material from a location of the molten material near an interface with a subjacent layer to the surface of the molten material.

3. The method of claim 1, wherein each energy pulse melts a portion of the solid material, and a duration between delivery of a first energy pulse and delivery of a second energy pulse immediately following the first energy pulse is selected to allow a portion of the solid material melted by the first energy pulse to refreeze.

4. The method of claim 1, wherein exposing the solid material to pulses of energy comprises exposing the solid material to a plurality of laser pulses, the first laser pulse having an intensity lower than one or more of the other laser pulses.

5. The method of claim 4, wherein the first laser pulse has an intensity lower than the other laser pulses.

6. The method of claim 3, wherein progressively recrystallizing the molten material comprises delivering pulses of energy to the molten material, the pulses of energy designed to form a crystalline solid from the molten material by progressing a crystallization front through the molten material in a direction opposite the direction the melt front progressed through the solid material.

7. The method of claim 6, wherein delivering pulses of energy to the molten material comprises delivering a plurality of laser pulses to the molten material, each laser pulse designed to melt a portion of the crystalline solid.

8. The method of claim 7, wherein a duration between delivery of a first laser pulse and delivery of a second laser pulse immediately following the first laser pulse is selected to crystallize a portion of the molten material larger than the portion of the crystalline solid melted by the first laser pulse.

9. A method of forming a solar cell, comprising:

forming large crystal domains in an active layer of the solar cell by progressively melting and recrystallizing the active layer using pulses of spatially uniform laser light.

10. The method of claim 9, wherein the active layer is treated by successively exposing portions of the active layer to the pulses of laser light.

11. The method of claim 9, wherein each pulse of uniformly distributed laser light extends a melt front within the active layer.

12. The method of claim 9, wherein portions of the active layer are successively exposed to pulses of uniformly distributed laser light, and each portion is exposed to a plurality of laser pulses comprising at least about 5 pulses of laser light.

13. The method of claim 12, wherein each plurality of laser pulses comprises a first set of one or more pulses and a second set of pulses, each pulse of the first set of one or more pulses has energy greater than the previous pulse, and each pulse of the second set of pulses has energy approximately equal to the previous pulse.

14. The method of claim 13, wherein the first set of one or more pulses is one pulse.

15. The method of claim 9, wherein the active layer comprises a p-type doped semiconductor layer, an intrinsic semiconductor layer, and an n-type doped semiconductor layer.

16. A method of forming a memory device, comprising:

forming a first conductive layer on a substrate;

forming a polycrystalline or monocrystalline semiconductor layer on the substrate by a process comprising;

depositing a semiconductor layer on the substrate;

progressively melting the semiconductor layer by exposing the semiconductor layer to pulses of energy, forming a molten semicondutor layer; and

recrystallizing the molten semiconductor layer; and

forming a second conductive layer on the substrate.

17. The method of claim 16, wherein exposing the semiconductor layer to pulses of energy comprises directing a plurality of laser pulses toward the semiconductor material, each pulse designed to melt a portion of the semiconductor material.

18. The method of claim 16, wherein the pulses of energy progress a melt front through the semiconductor material.

19. The method of claim 17, wherein the plurality of laser pulses comprises a first laser pulse having an intensity lower than the other laser pulses.

20. The method of claim 17, wherein each incident pulse of the plurality of laser pulses is separated from the next pulse by a duration selected to refreeze a portion of the semiconductor material melted by the incident pulse.

21. The method of claim 20, wherein each pulse of the plurality of laser pulses overlaps at least partially with neighboring pulses.

22. A method of forming a photonic device, comprising:

forming an compound semiconductor layer over a ceramic substrate; and

crystallizing the compound semiconductor layer by a process comprising;

directing pulses of energy toward the compound semiconductor layer, progressively melting the compound semiconductor layer to form a molten layer; and

crystallizing the molten layer to form a crystalline compound semiconductor layer.

23. The method of claim 22, wherein directing pulses of energy toward the compound semiconductor layer comprises directing a plurality of laser pulses toward the compound semiconductor layer, each pulse having energy selected to melt a portion of the compound semiconductor layer, and progressing a melt front through the compound semiconductor layer.

24. The method of claim 23, wherein the compound semiconductor layer comprises at least an n-type doped layer, a p-type doped layer, and a multiple quantum-well layer.

25. The method of claim 23, wherein the plurality of laser pulses comprises a first pulse having an intensity lower than the intensity of the other pulses.

26. The method of claim 22, wherein each incident pulse of energy is separated from the next pulse of energy by a duration selected to refreeze a portion of the molten layer smaller than the portion of the compound semiconductor layer melted by the incident pulse.

27. The method of claim 23, wherein crystallizing the molten layer comprises progressively crystalling the molten layer by directing pulses of energy toward the molten layer, wherein the pulses of energy are designed to progress a crystallization front through the molten material in a direction opposite the direction the melt front progressed through the compound semiconductor layer.