| 摘要 |
PURPOSE:To form a fine pattern of high aspect ratio in which the side etching amount of a photoresist of a lower layer is suppressed by converting the exposed region of the photoresist in the etching recess of the photoresist of the lower layer into a modified layer before at least the thickest photoresist region is etched. CONSTITUTION:With a photoresist pattern 14 and an SiO2 film 13 as masks a photoresist 12 of a lower layer is anisotropically etched perpendicularly by an RIE method or the like with oxygen gas. When 1mum of the photoresist on a raised semiconductor substrate is etched, the exposed portion of the photoresist 12 is plsma-treated with Freon gas to be converted to a modified layer 15 of several thousands Angstrom . Subsequently, the remaining 1mum of the thick region 12 is anisotropically etched perpendicularly by the RIE method or the like with the oxygen gas. Thus, since the ratio of the etching rates of the layer 15 on the side of the photoresist 14 to that of the inner photoresist 14 is slower by some fractions than the layer 15, a fine pattern of high aspect ratio having almost no side etching can be obtained.
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