Patent ID: 6841404
Filing Date: 2005-01-11
Classification: G03F

Abstract:
1. A method for determining an optical constant of an bottom antireflective layer formed between a resist film and an underlying substrate in an optical lithography process in a process for fabricating a semiconductor device, said resist film having an absorption coefficient α′ of 1.5 μm −1 to 3.0 μm −1 with respect to an exposure wavelength, a base of the absorption coefficient α′ being 10, said method comprising: expressing an nominal dose due to a variation in thickness of said resist film by the sum of a monotonic increase term and a damped oscillation term; and selecting an optical constant of said bottom antireflective layer so that a minimum value closing to a maximum point indicative of a maximum value on a curve of a variation in said nominal dose on a side that the thickness is larger than that at said maximum point is substantially equal to said maximum value, or so that no maximum point exist on said curve; wherein, expressing an exposure wavelength by λ and an extinction coefficient of the resist film by κ, said absorption coefficient α′ is a value having the following relationship with the λ and the κ;