| 摘要 |
<p>A collar oxide is formed in a semiconductor substrate having (1) a partially full trench, (2) (i) a fill surface defined by fill material partially filling said trench, (ii) an upper surface outside of said trench, and (iii) a trench sidewall surface not covered by said fill material, and (3) a conformal oxide layer overlying said fill, upper, and sidewall surfaces, by selectively etching as follows: (a) contacting the substrate with a mixture of hydrogen-containing fluorocarbon and an oxygen source under reactive ion etching conditions until at least a portion of the conformal oxide layer on the upper surface is removed, and (b) contacting the substrate from step (a) with a mixture of a hydrogen-free fluorocarbon and a diluent gas under reactive ion etching conditions to further remove conformal oxide remaining on the fill surface and to overetch the upper and fill surfaces, whereby a substantial portion of conformal oxide remains on the side walls to form the collar oxide. A further step (c) may be added after the overetching to remove any residual byproduct polymer deposits. Such an approach is especially adapted for use in the manufacture of high aspect ratio trench capacitors for integrated circuits, since it provides reduced degradation of pad nitride layers and may be conducted without the use of CO gas. <IMAGE></p> |
