Patent ID: 6355399
Filing Date: 2002-03-12
Classification: H01L

Abstract:
A method of forming a dual damascene pattern employing a single layer of photoresist, comprising the steps of:providing a semiconductor substrate said substrate having a surface; providing a light source; providing a gray tone mask, said gray tone mask having gradation of light passing capability such that light passes through said mask in varying degrees, said degrees varying between 0% or no light passing to 100% or all light passing through said gray tone mask, whereby furthermore gradation of light passing capability of said gray tone mask being such that light that strikes an underlying layer of photoresist imparts energy to said layer of photoresist in a pattern across a surface of said layer of photoresist and with a variation in a level of energy imparted and distributed across said layer of photoresist such that a pattern of a dual damascene structure is created in said layer of photoresist after developing said layer of photoresist, said gradation of light passing capability of said gray tone mask being achieved by keeping surface areas of openings through which light can pass through said mask constant while varying pitch between said openings; depositing a layer of photoresist over the surface of said substrate; positioning said gray tone mask between said substrate and said source of light such that a plane of said gray tone mask is parallel to a plane of a surface of said layer of photoresist; directing light provided by said light source to said layer of photoresist, said light passing through said gray tone mask before striking a surface of said layer of photoresist; removing said gray tone mask; developing said exposed layer of photoresist, removing exposed photoresist, creating a pattern in said layer of photoresist; transferring said pattern in said layer of photoresist into the surface of said substrate; and removing said photoresist from the surface of said substrate.