| 摘要 |
PURPOSE:To make it possible to form a fine trench-pattern of high aspect ratio for an Si substrate, by forming an oxide film pattern on an silicon substrate, and forming a side-wall film being a mask for trench etching on the side of the oxide film pattern. CONSTITUTION:A thermal oxide film 12 of 7,000Angstrom thick is formed on an Si substrate 11. An oxide film pattern 12a having an L&S(LINE&SPACE) interval is formed by a photolithography and a RIE methods. a PSG film 13 is formed thereon covering the whole surface. By the RIE having an excellent etching directivity, the whole surface is subjected to etching, and the PSG film is left as a side wall 13a on the side of an thermal oxide pattern 12a. By changing, in this case, the film thickness of the PSG film 13, the side wall 13a of the PSG film left on the side of the thermal oxide pattern 12a can be changed, so that the dimension of a pattern spacing can be arbitrarily controlled. Then the Si substrate 11 is scraped by the RIE method using a gas, BCl3+Cl2, wherein the formed pattern is applied to a mask. Highly accurate and fine trenches 14 of the Si substrate which have a high aspect ratio can be formed, thereby.
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