Using different transmittance with attenuate phase shift mask (APSM) to compensate ADI critical dimension proximity

摘要

An attenuating phase shifting mask and method of forming an attenuating mask for patterns having both isolated and dense contact holes and/or line/space patterns on the same mask. In the more isolated regions of the contact hole mask the contact holes have 0° phase shift and 100% light transmission. In the dense regions of a contact hole mask the contact holes have 0° phase shift and a second thickness of light absorbing material with a relatively low light absorption. The region around the contact holes have 180° phase shift and a first thickness of light absorbing material with a relatively high light absorption. The lines of a line/space mask have 180° phase shift and a first thickness of light absorbing material with a relatively high light absorption. The spaces between the isolated lines have 0° phase shift and 100% light transmission. The spaces between the dense lines 0° phase shift and a second thickness of light absorbing material with a relatively low light absorption. The dense and isolated pattern regions are separated using logic operations on the mask design data.