| 摘要 |
PURPOSE:To eliminate an element pattern abnormality at the periphery of a projection by flattening the projection on a wafer by a high temperature baking, further searching the projection uniformly by etching and then selectively etching the projections. CONSTITUTION:A photoresist 2 is spin coated on a GaAs wafer 1 at 3000 rpm. Then, the wafer 1 is baked at 200 deg.C in a nitrogen atmosphere. At this time, the photoresist 2 is averaged on the surface, and the thickness of the photoresist on the projections 4, such as oval defect becomes thin as compared with the thickness of the photoresist on a region 3. After baking, the photoresist 2 is uniformly ashed by acid plasma etching until the projections 4 are exposed on the surface. Then, when the wafer is immersed in an etchant to etch the projections 4, the projections of the wafer are removed to be flattened.
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