Contact Layout Structure for Semiconductor Etching Control

The contact opening formation process is segmented into two distinct etching processes: a first etching process for forming smaller contact openings in iso regions, and a second etching process for forming larger share contact openings in dense regions. This segmentation allows each etching process to be independently optimized for its specific contact type, resolving the micro-loading effect and density difference issues that arise when using a single etching process for both contact types.

The etching process is divided into two separate processes with different parameters and conditions. The first etching process uses parameters optimized for forming complete contact openings in iso regions without over-etching. The second etching process uses parameters optimized for forming share contact openings with appropriate depth control. This segmentation eliminates the harmful over-etching effect that occurs when a single etching process is used for both contact types.

The photomask pattern design incorporates preliminary spacing considerations that prevent opening merging during the etching process. The mask patterns are designed with appropriate spacing and geometry to account for etching variations and micro-loading effects, ensuring that even when contact openings are positioned closely in dense regions, they do not merge during etching. This preliminary action in the mask design stage prevents the merging problem before it occurs in the etching process.