Patent ID: 8071275
Filing Date: 2011-12-06
Classification: G03F

Abstract:
1. A method for planarizing a surface of a photoresist layer on a substrate of a wafer, comprising: positioning over a starting surface of the photoresist layer a gray-scale mask having a pattern that correlates with a gradient height profile of unevenness present on the starting surface; patterning the photoresist layer by using the gray-scale mask to produce the pattern of the gray-scale mask in the photoresist layer which, in effect, produces a patterned profile of evenness in the photoresist layer underlying the gradient height profile of unevenness; and developing the patterned photoresist layer such that a three-dimensional portion thereof corresponding to the gradient height profile of unevenness located above the patterned profile of evenness is removed which, in effect, leaves behind a resulting surface of the photoresist layer made substantially more even and thus substantially in a planarized condition, said patterning further including overexposing a marginal edge portion of the photoresist layer to create a negative step into the resulting surface and an outer edge on the photoresist layer extending around the wafer.