Critical Dimension and Profile Control of Photoresist Images
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
By interrupting the development process, the "induction period" (time before any removal of unexposed photoresist is observed) is utilized more than once to allow complete removal of the exposed photoresist before any significant amount of unexposed photoresist is removed. This procedure preserves size of small exposed regions in areas of thin photoresist while small exposed regions in thick photoresist areas are completely cleaned out. The procedure also results in steeper hole walls in the developed photoresist. Spin-applied, solvent-cast photoresist tends to planarize over the topography of integrated circuits. As a result, thickness of the cured photoresist can vary by a factor of two in different areas of a wafer.