Background technology
Solar-energy photo-voltaic cell is one of the most promising renewable energy utilization mode at present.Wherein crystal silicon solar battery is owing to its aboundresources, and the technical maturity advantages of higher occupies and incite somebody to action the leading position of occuping market for a long time.In all kinds of crystal silicon solar battery technology that developing at present, the HIT battery of producing with Japanese Sanyo company is that the silicon/crystalline silicon heterojunction solar cell of representative gets more and more people's extensive concerning with the advantages such as technology maturity of its high conversion efficiency, suitable scale of mass production.
People generally believe that the crystal silicon chip surface passivation layer is the key point of decision silicon/crystalline silicon heterojunction solar cell performance to the passivation effect of silicon chip surface.The conversion efficiency of the HIT battery of Sanyo company has reached 23.0%.At present, the material that is used as this passivation layer mainly contains a-Si:H film that adopts PECVD method or the preparation of heated filament CVD method or the a-SiOx:H film that the PECVD method prepares, and has all obtained passivation effect preferably.For Fz silicon, minority carrier life time can reach the ms magnitude after transpassivation.But it is found that, after preparing passivation layer, carry out heat-treating at 200~300 ℃ under Ar gas atmosphere, hydrogen atmosphere or the vacuum condition, can further improve the passivation effect of passivation layer silicon chip surface.Wherein hydrogen atmosphere is optimum.The minority carrier life time of Fz silicon can reach 5~6ms after the heat treatment.The passivation effect of a-Si:H or a-SiOx:H comes from the structure of the si-h bond of film and silicon chip surface formation, under suitable temperature and atmosphere, heat-treats, and has changed the structure of si-h bond in the film, thereby has improved its passivation effect.But this heat treatment process required time is longer, needs several hrs even longer, and this point is unfavorable for large batch of suitability for industrialized production.
Summary of the invention
Technical problem to be solved by this invention provides a kind of heat treatment method of heterojunction crystal silicon solar battery passivation layer; This method can be improved the passivation effect of passivation layer to silicon chip surface; Thereby improve the conversion efficiency of solar cell; And, greatly the shortening heat treatment process time, enhance productivity than inert gas atmosphere, hydrogen atmosphere or the vacuum heat treatment process of routine.
The heat treatment method of a kind of heterojunction crystal silicon solar battery passivation layer of the present invention comprises:
Adopt PECVD method or heated filament CVD legal system to be equipped with heterojunction crystal silicon solar battery passivation layer film,, the silicon chip of passivation layer is handled 1min~60min in 200~300 ℃ with the hydrogen atmosphere that contains hydrogen plasma that produces in the PECVD method; Or the hydrogen atmosphere of the hydrogen atoms that produces with heated filament CVD method, the silicon chip of passivation layer is handled 1min~60min in 200~300 ℃.
Said passivation layer film is thicker than silicon/crystalline silicon heterojunction solar cell device architecture desired thickness.
The said technological parameter of the silicon chip of passivation layer being handled with the hydrogen atmosphere that contains hydrogen plasma that produces in the PECVD method by: being added radio frequency power density on the pole plate is 0.01~1.2W/cm
2, air pressure is 5~100Pa.
The technological parameter that the hydrogen atmosphere of the said hydrogen atoms that produces with heated filament CVD method is handled the silicon chip of passivation layer is: the temperature of heated filament is 1500~2200 ℃, and air pressure is 0.1~50Pa.
Beneficial effect
The present invention adopts the active hydrogen atmosphere of high energy to heat-treat as the silicon chip that is used for the silicon/crystalline silicon heterojunction solar cell of passivation layer possessing a-Si:H or a-SiOx:H; Can improve the passivation effect of passivation layer to silicon chip surface; Thereby improve the conversion efficiency of solar cell, and than inert gas atmosphere, hydrogen atmosphere or the vacuum heat treatment process of routine, shortening heat treatment process time greatly; Enhance productivity, have a good application prospect.
Embodiment
Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only to be used to the present invention is described and be not used in the restriction scope of the present invention.Should be understood that in addition those skilled in the art can do various changes or modification to the present invention after the content of having read the present invention's instruction, these equivalent form of values fall within the application's appended claims institute restricted portion equally.
Embodiment 1
Cleaning a-Si:H that clean N-type silicon both side surface respectively prepares one deck 25nm as passivation layer with the PECVD method, the minority carrier life time after the passivation is 320 μ s.
High energy active hydrogen plasma so that the PECVD method produces is heat-treated the silicon chip that has deposited passivation layer, and concrete technological parameter is following: adopt the radio frequency source activated plasma of 13.56MHz, adding radio frequency power density on the pole plate is 0.08W/cm
2, air pressure 25Pa, silicon chip are heated to 280 ℃, time 30min.
Minority carrier life time has reached 600 μ s after the heat treatment, and the reduced thickness of passivation layer has arrived 15nm.As adopting conventional heat treatment, heat treatment time needs about 120min.
Embodiment 2
Cleaning a-Si:H that clean N-type silicon both side surface respectively prepares one deck 20nm as passivation layer with heated filament CVD method, the minority carrier life time after the passivation is 350 μ s.
High energy active hydrogen atom atmosphere so that heated filament CVD method produces is heat-treated the silicon chip that has deposited passivation layer, and concrete technological parameter is following: adopt tungsten filament as heated filament, the hot-wire temperature is heated to 1800 ℃, and air pressure 10Pa, silicon chip are heated to 220 ℃, time 25min.
Minority carrier life time has reached 680 μ s after the heat treatment, and passivation layer thickness has been thinned to 12nm.As adopting conventional heat treatment, heat treatment time needs about 120min.
Embodiment 3
Cleaning a-Si:H that clean N-type silicon both side surface respectively prepares one deck 25nm as passivation layer with the PECVD method, the minority carrier life time after the passivation is 320 μ s.
High energy active hydrogen plasma so that the PECVD method produces is heat-treated the silicon chip that has deposited passivation layer, and concrete technological parameter is following: adopt the radio frequency source activated plasma of 13.56MHz, adding radio frequency power density on the pole plate is 0.8W/cm
2, air pressure 75Pa, silicon chip are heated to 260 ℃, time 40min.
Minority carrier life time has reached 580 μ s after the heat treatment, and the reduced thickness of passivation layer has arrived 14nm.As adopting conventional heat treatment, heat treatment time needs about 120min.
Embodiment 4
Cleaning a-Si:H that clean N-type silicon both side surface respectively prepares one deck 20nm as passivation layer with heated filament CVD method, the minority carrier life time after the passivation is 350 μ s.
High energy active hydrogen atom atmosphere so that heated filament CVD method produces is heat-treated the silicon chip that has deposited passivation layer, and concrete technological parameter is following: adopt tungsten filament as heated filament, the hot-wire temperature is heated to 2100 ℃, and air pressure 30Pa, silicon chip are heated to 210 ℃, time 10min.
Minority carrier life time has reached 670 μ s after the heat treatment, and passivation layer thickness has been thinned to 15nm.As adopting conventional heat treatment, heat treatment time needs about 120min.