A kind of wet oxidation prepares the method for earth silicon mask
Technical field
The present invention relates to a kind of method that wet oxidation prepares earth silicon mask, be mainly used in crystalline silicon selective emitter battery mask processed aspect, specifically plant the method that the oxidation of selective emitter of crystalline silicon solar cell cell wet-method prepares earth silicon mask in one.
Background technology
Solar cell main development direction is reduce costs and improve transformation efficiency, and under the manufacture of solar cells mode of standard, the lifting of efficiency has approached the limit at present, and the photovoltaic industry has all been focused on high-efficiency battery technique.In numerous technology, the selective emitter battery is to be hopeful one of method of raising the efficiency in production technology, so-called selective emitting electrode structure is: form highly doped refreshing diffusion region near machine under gate electrode line, in other zones, form low-doped shallow diffusion region.In the selective emitter battery process that wherein prepared by twice diffusion method by oxide-diffused obtains for the first time oxide layer as diffusion impervious layer, then by photoetching or corrosive slurry, remove oxide layer, then form selective emitter by common diffusion way.Wherein first step diffusible oxydation mask processed becomes one of its core technology, only makes this mask can successfully keep out heavy doping for the second time, could form the structure of selective emitter.
Summary of the invention
The objective of the invention is can not effectively keep out the problem that spreads for the second time the phosphorus atoms diffusion and proposed a kind of method that wet oxidation prepares earth silicon mask at present by common diffusion furnace diffusible oxydation, forming for the first time shallow diffusion layer.
Purpose of the present invention can be achieved through the following technical solutions:
A kind of wet oxidation prepares the method for earth silicon mask, it is characterized in that it comprises the following steps:
(1) silicon chip of making herbs into wool is sent into to wet oxidation diffusion furnace reaction boiler tube, furnace tube temperature is heated to 770 ~ 850 ℃ in 10min, passes into nitrogen flow 5-8slm simultaneously, continues 3min;
(2) pass into nitrogen flow 3-7slm, oxygen flow 300 ~ 500sccm, nitrogen carries phosphorus oxychloride gas flow 1300-1700sccm, continues 15-18min;
(3) pass into wet oxygen flow 2700 ~ 3000sccm, continue 10-12min;
(4) with 4 ℃ of speed rising furnace tube temperatures to 870 per minute ~ 890 ℃, pass into nitrogen flow is 10 ~ 13slm simultaneously;
(5) maintain the temperature at 870 ~ 890 ℃, passing into the wet oxygen flow is 5 ~ 7slm, and the wet oxygen temperature is controlled at 70 ~ 80 ℃, continues 15 ~ 17min;
(6) passing into nitrogen flow is 15 ~ 20slm, is cooled to 830 ℃, makes earth silicon mask.
In step of the present invention (1), the interior temperature of boiler tube is heated to 780 ℃.
Passing into nitrogen flow in step of the present invention (2) is 5slm, oxygen flow 400sccm, and the phosphorus oxychloride gas flow that nitrogen carries is 1500sccm.
In step of the present invention (3), the wet oxygen flow is 2800sccm, duration 11min.
In step of the present invention (5), temperature constant is at 880 ℃.Passing into the wet oxygen flow is 6slm, and the temperature of wet oxygen is 75 ℃, and the duration is 16min.
Beneficial effect of the present invention: earth silicon mask prepared by the present invention's wet oxidation used can reduce the mask film formation time aborning, enhance productivity, mask structure is fine and close and even, the phosphorus atoms that can effectively keep out in the secondary diffusion further spreads, and makes the selective emitter battery structure more stable.
Embodiment
Below in conjunction with specific embodiment, the invention will be further described.
Embodiment 1
A kind of wet oxidation prepares the method for earth silicon mask, it is characterized in that it comprises the following steps: (1) sends the silicon chip of making herbs into wool into wet oxidation diffusion furnace reaction boiler tube, and furnace tube temperature is heated to 810 ℃ in 10min, passes into nitrogen 6.5slm simultaneously; (2) pass into nitrogen flow 3.5slm, oxygen flow 350sccm, nitrogen carries phosphorus oxychloride gas flow 1300sccm, continues 17min:(3) and pass into wet oxygen flow 2750sccm, continue 10.5min; (4) with 4 ℃ of speed rising furnace tube temperatures to 878 ℃ per minute, pass into nitrogen flow is 12slm simultaneously; (5) maintain the temperature at 878 ℃, passing into the wet oxygen flow is 5.5slm, and the wet oxygen temperature is controlled at 74 ℃, continues 15.5min; (6) passing into nitrogen flow is 18slm, is cooled to 830 ℃, makes earth silicon mask.
Embodiment 2
A kind of wet oxidation prepares the method for earth silicon mask, it is characterized in that it comprises the following steps: (1) sends the silicon chip of making herbs into wool into wet oxidation diffusion furnace reaction boiler tube, and furnace tube temperature is heated to 780 ℃ in 10min, passes into nitrogen 5.8slm simultaneously; (2) pass into nitrogen flow 5slm, oxygen flow 400sccm, nitrogen carries phosphorus oxychloride gas flow 1500sccm, continues 18min:(3) and pass into wet oxygen flow 2800sccm, continue 11min; (4) with 4 ℃ of speed rising furnace tube temperatures to 880 ℃ per minute, pass into nitrogen flow is 13slm simultaneously; (5) maintain the temperature at 880 ℃, passing into the wet oxygen flow is 6slm, and the wet oxygen temperature is controlled at 75 ℃, continues 16min; (6) passing into nitrogen flow is 15slm, is cooled to 830 ℃, makes earth silicon mask.
Embodiment 3
A kind of wet oxidation prepares the method for earth silicon mask, it is characterized in that it comprises the following steps: (1) sends the silicon chip of making herbs into wool into wet oxidation diffusion furnace reaction boiler tube, and furnace tube temperature is heated to 780 ℃ in 10min, passes into nitrogen 7.5slm simultaneously; (2) pass into nitrogen flow 6.5slm, oxygen flow 500sccm, nitrogen carries phosphorus oxychloride gas flow 1650sccm, continues 15min:(3) and pass into wet oxygen flow 2980sccm, continue 10min; (4) with 4 ℃ of speed rising furnace tube temperatures to 890 ℃ per minute, pass into nitrogen flow is 11slm simultaneously; (5) maintain the temperature at 890 ℃, passing into the wet oxygen flow is 6.7slm, and the wet oxygen temperature is controlled at 70 ℃, continues 17min; (6) passing into nitrogen flow is 19slm, is cooled to 830 ℃, makes earth silicon mask.