IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0118295
(2011-05-27)
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등록번호 |
US-8399331
(2013-03-19)
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발명자
/ 주소 |
- Moslehi, Mehrdad M.
- Rana, Virendra V.
- Liang, JianJun
- Anbalagan, Pranav
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
13 인용 특허 :
89 |
초록
▼
Laser processing schemes are disclosed for producing various types of hetero-junction and homo-junction solar cells. The methods include base and emitter contact opening, selective doping, and metal ablation. Also, laser processing schemes are disclosed that are suitable for selective amorphous sili
Laser processing schemes are disclosed for producing various types of hetero-junction and homo-junction solar cells. The methods include base and emitter contact opening, selective doping, and metal ablation. Also, laser processing schemes are disclosed that are suitable for selective amorphous silicon ablation and selective doping for hetero-junction solar cells. These laser processing techniques may be applied to semiconductor substrates, including crystalline silicon substrates, and further including crystalline silicon substrates which are manufactured either through wire saw wafering methods or via epitaxial deposition processes, that are either planar or textured/three-dimensional. These techniques are highly suited to thin crystalline semiconductor, including thin crystalline silicon films.
대표청구항
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1. A method of processing a thin crystalline silicon substrate, said method comprising the steps of: providing a thin crystalline silicon substrate with a substrate thickness in the range of approximately 1 micron to 100 microns suitable for use in an all back-contact back-junction solar cell;formin
1. A method of processing a thin crystalline silicon substrate, said method comprising the steps of: providing a thin crystalline silicon substrate with a substrate thickness in the range of approximately 1 micron to 100 microns suitable for use in an all back-contact back-junction solar cell;forming base isolation regions in said thin crystalline silicon substrate;performing pulsed laser ablation of a substance chosen from the group consisting of silicon oxide, silicon nitride, aluminum oxide, silicon oxynitride, and silicon carbide on said thin crystalline silicon substrate to form base openings;performing selective doping of base regions;performing selective doping of emitter regions;forming contacts for base regions and emitter regions;forming metallization on said base regions and said emitter regions; andperforming pulsed laser ablation of a predetermined portion of said metallization to form a first set of metal lines connected to said base regions and a second set of metal lines connected to said emitter regions. 2. The method of claim 1, wherein said step of performing laser ablation of said predetermined portion of said metallization is carried out below an oxide ablation threshold for said thin crystalline silicon substrate. 3. The method of claim 1, wherein said step of performing laser ablation of said predetermined portion of said metallization is carried out above an oxide ablation threshold for said thin crystalline silicon substrate, thereby ablating said metallization in a single pass. 4. The method of claim 3, wherein said metallization comprises reflective metallization, and said step of performing laser ablation of said predetermined portion of said metallization comprises ablating with a first laser having an infrared wavelength and a pulse width approximately in the range of approximately 10 nanoseconds to 800 nanoseconds, followed by ablating with a second laser having a pulse width less than approximately 700 nanoseconds. 5. The method of claim 1, wherein said step of forming base isolation regions in said thin crystalline silicon substrate is carried out via a laser silicon ablation process and using a pulsed laser having a wavelength of approximately 800 nm or less and a pulse width less than approximately 100 picoseconds. 6. The method of claim 5, wherein said wavelength is approximately 355 nm or less. 7. The method of claim 5, wherein said pulse width is less than approximately 20 picoseconds. 8. The method of claim 1, wherein said step of forming base isolation regions in said thin crystalline silicon substrate is carried out via pulsed laser ablation of a deposited borosilicate glass layer. 9. The method of claim 1, wherein said metallization comprises a stack of a first metal, a second metal, and a third metal, wherein said third metal comprises a low-melting-point solder element comprising at least tin. 10. The method of claim 9, wherein said first metal comprises aluminum. 11. The method of claim 10, wherein said aluminum has a thickness approximately in the range of approximately 1,000 to 10,000 Angstroms. 12. The method of claim 11, wherein said solder is chosen from the group consisting of tin solder, tin-lead solder, tin-bismuth solder, and tin-silver solder. 13. The method of claim 9, wherein said second metal has a thickness approximately in the range of 100 to 1,500 Angstroms. 14. The method of claim 9, wherein said second metal is chosen from the group consisting of nickel, nickel-vanadium, and cobalt. 15. The method of claim 14, wherein said solder has a thickness less than approximately 5,000 Angstroms. 16. A method of processing a thin crystalline silicon substrate, said method comprising the steps of: providing a thin crystalline silicon substrate with a substrate thickness in the range of approximately 1 micron to 100 microns suitable for use in a front contact solar cell;forming base isolation regions in said thin crystalline silicon substrate;performing pulsed laser ablation of a substance chosen from the group consisting of silicon oxide, silicon nitride, aluminum oxide, silicon oxynitride, and silicon carbide on said thin crystalline silicon substrate to form base openings;selectively doping an emitter region via a laser doping process;forming contacts for base regions and emitter regions; andperforming selective silicon oxide ablation for formation of isolated backside metal contacts. 17. A method of processing a thin crystalline silicon substrate, said method comprising the steps of: providing a thin crystalline silicon substrate with a substrate thickness in the range of approximately 1 micron to 100 microns suitable for use in a hetero-junction solar cell, said thin crystalline silicon substrate comprising at least a doped amorphous silicon layer in contact with an oppositely doped crystalline silicon base and a transparent conducting oxide layer on said doped amorphous silicon layer;selectively ablating a portion of said transparent conducting oxide layer and said doped amorphous silicon layer via a pulsed laser having a pulse width less than about 700 femtosecond pulsed laser having a wavelength less than approximately 1.06 microns;forming an undoped amorphous silicon layer for base to emitter isolation on said thin crystalline silicon substrate;selectively ablating a portion of said undoped amorphous silicon layer via said laser having a pulse width less than about 700 femtosecond pulsed laser having a wavelength less than approximately 1.06 microns; andperforming pulsed laser ablation of oxide for contacts to an emitter region and a base region on said thin crystalline silicon substrate. 18. The method of claim 17, wherein said laser has a wavelength of approximately 532 nm or less.
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