| 摘要 |
PURPOSE:To control the cross-sectional shape of polycrystalline silicon in etching as a desired shape with good reproducibility, when the polycrystalline silicon is etched in ECR discharge plasma, by further mixing nitriding gas with chlorine and sufur hexafluoride. CONSTITUTION:A gas, which is introduced through a gas introducing system 6, is made to be ECR plasma with a magnetic field, which is produced by a magnetic field producing coil 5 that is provided at the outer surface of a plasma chamber 1 and a microwave electric field. The plasma is guided by the divergent magnetic field produced by the magnetic field producing coil 5 and inputted into a sample 9 through a plasma-stream lead-out window 8. Then the surface of the sample 9 is etched. Here, in addition to chlorine with a specified flow rate and sulfur hexafluoride, nitrogen is introduced at a specified flow rate. When etching is performed at a specified pressure, an anisotropic shape is readily obtained. The cross-sectional shape in etching can be adjusted by changing the mixing ratio of nitrogen gas. When nitrogen gas is added by 10-20%, polycrystalline silicon having the desirable etching cross-sectional shape with a forward taper angle of 80-90 degrees can be etched.
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