Method of forming photoresist pattern and semiconductor device employing the same
A method of forming a photoresist pattern includes forming a material layer on a substrate, coating a photoresist on the material layer, and forming photoresist patterns by performing at least two times a process of exposing and developing the coated photoresist. A semiconductor device includes a material layer formed on a substrate, and photoresist patterns formed by performing two or more times an exposing and developing process on a photoresist coated on the material layer, wherein the material layer is etched using the photoresist patterns as a mask.
1 . A method of forming a photoresist pattern, comprising:
forming a material layer on a substrate;
coating a photoresist on the material layer; and
forming photoresist patterns by performing at least two times a process of exposing and developing the coated photoresist.
2 . The method according to claim 1 , wherein the material layer includes a gate polysilicon layer and a gate oxide layer.
3 . The method according to claim 1 , wherein the forming of the photoresist patterns includes:
primarily exposing and developing the coated photoresist to a thickness of an optimal depth of focus (DOF); and
secondarily exposing and developing the primarily exposed and developed photoresist to a thickness of an optimal DOF.
4 . The method according to claim 1 , wherein the exposing and developing process is performed at two or more times until the coated photoresist is completely exposed.
5 . The method according to claim 1 , wherein the substrate has a global step difference between cell blocks or peripheral regions.
6 . The method according to claim 1 , further comprising a hard baking process of performing a thermal treatment on the photoresist patterns.
7 . The method according to claim 1 , further comprising planarizing the coated photoresist.
8 . The method according to claim 7 , wherein the planarization of the photoresist includes hardening the photoresist within a hot plate oven or a convection oven.
9 . The method according to claim 8 , further comprising irradiating an ultraviolet (UV) having a wavelength of 150-300 nm after the hardening of the photoresist.
10 . A method of manufacturing a semiconductor device, comprising:
forming a material layer on a substrate;
coating a photoresist on the material layer;
forming photoresist patterns by performing at least two times a process of exposing and developing the coated photoresist; and
etching the material layer using the photoresist patterns as a mask.
11 . The method according to claim 10 , wherein the material layer includes a gate oxide layer and a gate polysilicon layer.
12 . The method according to claim 10 , wherein the forming of the photoresist patterns includes:
primarily exposing and developing the coated photoresist to a thickness of an optimal DOF; and
secondarily exposing and developing the primarily exposed and developed photoresist to a thickness of an optimal DOF.
13 . The method according to claim 10 , wherein the exposing and developing process is performed at two or more times until the coated photoresist is completely exposed.
14 . The method according to claim 10 , wherein the substrate has a global step difference between cell blocks or peripheral regions.
15 . The method according to claim 10 , wherein the etching process is performed using a reactive ion etching (RIE).
16 . The method according to claim 10 , further comprising planarizing the coated photoresist.
17 . The method according to claim 16 , wherein the planarization of the photoresist includes hardening the photoresist within a hot plate oven or a convection oven.
18 . The method according to claim 17 , wherein the hardening process includes irradiating an ultraviolet (UV) having a wavelength of 150-300 nm.
19 . A semiconductor device comprising:
a material layer formed on a substrate; and
photoresist patterns formed by performing two or more times an exposing and developing process on a photoresist coated on the material layer, wherein the material layer is etched using the photoresist patterns as a mask.
20 . The semiconductor device according to claim 19 , wherein the photoresist patterns are formed by primarily exposing and developing the coated photoresist to a thickness of an optimal DOF, and secondarily exposing and developing the primarily exposed and developed photoresist to a thickness of an optimal DOF.