Method for laser purification of polycrystalline silicon wafer
A polycrystalline silicon wafer and laser technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve problems such as laser purification applications that have not yet been seen, and achieve the effect of reducing re-recycling and processing
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Embodiment 1
[0028] After cleaning and drying the polycrystalline silicon wafer with a thickness of 180 μm, place the silicon wafer on the quartz wafer, and place the quartz wafer on the heating platform to prevent the heating platform from polluting the silicon wafer. The preheating temperature is 300°C, and the preheating time is 30s. Then use a continuous Nd:YAG laser with a rectangular spot shape, a length of 20mm, and a width of 0.5mm. The laser power is evenly distributed. The laser power is 230W. scanning. Then the silicon wafer was taken out and annealed at 700° C. for 15 minutes in a nitrogen atmosphere. Take out the silicon wafer, etch the laser irradiation surface of the silicon wafer with plasma, and the etching gas is SF 6 , the gas flow rate is 25 sccm, and the target silicon wafer is obtained after etching 4 μm.
[0029] Using SIMS to detect the iron content within 10 μm depth of the sample shows that the iron content in the crystal grains in the original silicon wafer is...
Embodiment 2
[0031] After cleaning and drying the polycrystalline silicon wafer with a thickness of 190 μm, place the silicon wafer on the quartz wafer, and place the quartz wafer on the heating platform to prevent the heating platform from polluting the silicon wafer. The preheating temperature is 250°C, and the preheating time is 60s. Then use a continuous Nd:YAG laser with a rectangular spot shape, a length of 20mm, and a width of 0.5mm. The laser power is evenly distributed. The laser power is 220W. scanning. Then the silicon wafer was taken out and annealed at 600° C. for 20 min in a nitrogen atmosphere. Take out the silicon wafer, etch the laser irradiation surface of the silicon wafer with plasma, and the etching gas is SF 6 , the gas flow rate is 25 sccm, and the target silicon wafer is obtained after etching 3 μm.
[0032] Detected iron content from the original silicon wafer iron content in 10 15 ~10 17 atoms / cm 3 order of magnitude, and its iron content is reduced to less ...
Embodiment 3
[0034] After cleaning and drying the polycrystalline silicon wafer with a thickness of 200 μm, place the silicon wafer on the quartz wafer, and place the quartz wafer on the heating platform to prevent the pollution of the silicon wafer by the heating platform. The preheating temperature is 450°C, and the preheating time is 30s. Then use a continuous Nd:YAG laser with a circular spot shape, a diameter of 2 cm, a Gaussian power distribution, and a laser power of 300 W. The laser beam is 90° to the plane of the silicon wafer, and is scanned at a speed of 4 mm / s relative to the silicon wafer. Then the silicon wafer was taken out and annealed at 700° C. for 20 min in a nitrogen atmosphere. Take out the silicon wafer, etch the laser irradiation surface of the silicon wafer with plasma, and the etching gas is SF 6 , the gas flow rate is 25 sccm, and the target silicon wafer is obtained after etching 3 μm.
[0035] Detected iron content from the original silicon wafer iron content ...
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