| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of thin horn-like burrs on the upper part of the side wall of a cylindrical cell when it is formed by the second polycrystalline silicon. SOLUTION: After an oxide film 9 is etched under the condition of CHF3 /O2 =90/4 sccm, 5 pa and 100 W using the resist pattern 10 shown in (a) in such a manner that a forward tapered cylindrical shape is formed as shown in (b), the first polycrystalline silicon 8 is anisotropically etched, the resist pattern 10 is removed and the second polycrystalline silicon film 11 is formed. Then, the polycrystalline silicon film 11 is etched back under the condition of 10 mTorr and source/bottom RF=400/70 W under which the side wall is strongly protected. Lastly, a cylindrical cell C is formed by the second polycrystalline silicon 11 by removing the oxide film 9 by wet etching under the condition of H2 O:HF=5:1 as shown in (d). |
