| 摘要 |
<p>We have developed a method of selectively etching silicon nitride relative to oxides in a high-density plasma chamber of the kind presently known in the art. We have obtained selectivities for silicon nitride: silicon oxide in the range of about 15: 1 to about 24: 1. We have employed the method in the etching of silicon nitride spacers for sub 0.25 µm devices, where the spacers are adjacent to exposed oxides during the etch process. We have obtained silicon nitride spacers having rounded top corners and an extended 'tail' toward the bottom outer edge of the nitride spacer. The method employs a plasma source gas, which typically includes SF6, HBr, N2, and optionally, O2. Typically, the pressure in the etch chamber during etching is at least 4.7 Pa (35 mTorr) and the substrate temperature is about 20°C or less.</p> |
