Methods of forming patterns
A method of forming sub-resolution features that includes: exposing a photoresist layer formed over a substrate to a first ultraviolet light (UV) radiation having a first wavelength of 365 nm or longer through a mask configured to form features at a first critical dimension, the photoresist layer including first portions exposed to the first UV radiation and second portions unexposed to the first UV radiation after exposing with the first UV radiation; exposing the first portions and the second portions to a second UV radiation; and developing the photoresist layer after exposing the photoresist layer to the second UV radiation to form the sub-resolution features having a second critical dimension less than the first critical dimension.
1 . A method of forming sub-resolution features, the method comprising:
exposing a photoresist layer formed over a substrate to a first ultraviolet light (UV) radiation having a first wavelength of 365 nm or longer through a mask, the photoresist layer comprising first portions exposed to the first UV radiation and second portions unexposed to the first UV radiation after exposing with the first UV radiation, the second portions having a first height and a first critical dimension;
exposing the first portions and the second portions to a second UV radiation, the second UV radiation being a blanket radiation with no pattern;
forming a plurality of features, the forming comprising developing the photoresist layer after exposing the photoresist layer to the second UV radiation, the plurality of features having a second height and a second critical dimension less than the first critical dimension, the second height being less than the first height; and
spacer patterning, the spacer patterning comprising:
depositing a layer of a spacer material over the plurality of features;
performing a spacer etch back to remove a lateral portion of the spacer material;
performing a pull etch to remove the plurality of features and form a spacer pattern; and
performing a pattern transfer etch using the spacer pattern as an etch mask.
2 . The method of claim 1 , further comprising, before developing, performing a post-exposure bake by thermally treating the substrate.
3 . The method of claim 1 , further comprising selecting conditions for exposing the first portions and the second portions to the second UV radiation to form the sub-resolution wherein the plurality of features have a width between 200 nm and 360 nm, a height between 20 nm and 900 nm, or a ratio of height to width between 3 and 100.
4 . The method of claim 1 , wherein exposing the first portions and the second portions to the second UV radiation is performed using a pixel-based projection system having an array of independently addressable projection points.
5 . The method of claim 1 , wherein the first wavelength is 365 nm and the second UV radiation has a wavelength of 266 nm.
6 . The method of claim 1 , further comprising generating the first UV radiation and the second UV radiation in a common lithography tool.
7 . A method of forming sub-resolution features, the method comprising:
exposing a photoresist layer formed over a substrate to a first ultraviolet light (UV) radiation having a first wavelength of 365 nm or longer through a first mask, the photoresist layer comprising first portions exposed to the first UV radiation and second portions unexposed to the first UV radiation after exposing with the first UV radiation, the second portions having a first critical dimension;
developing the photoresist layer after exposing the photoresist layer to the first UV radiation to remove the first portions;
depositing a resin over the photoresist layer;
exposing the second portions to a second UV radiation having a second wavelength; and
developing the photoresist layer after exposing the photoresist layer to the second UV radiation to form the sub-resolution features having a second critical dimension less than the first critical dimension, the sub-resolution features comprising a trench between the photoresist layer and the resin.
8 . The method of claim 7 , wherein depositing the resin before exposing the second portions to the second UV radiation, the second UV radiation inducing a photochemical reaction generating an acid within the second portions, the acid laterally diffusing into the resin to form acid-reacted layers on side walls of the resin.
9 . The method of claim 8 , wherein developing the photoresist layer after exposing the photoresist layer to the second UV radiation removes the acid-reacted layers, and wherein widths of the acid-reacted layers determine the second critical dimension.
10 . The method of claim 8 , further comprising, before exposing the second portions to the second UV radiation, inserting a second mask into an optical path of the second UV radiation.
11 . The method of claim 7 , wherein the resin is deposited over the photoresist layer after exposing the second portions to the second UV radiation, wherein exposing the second portions comprises forming third portions exposed to the second UV radiation by converting a portion of the second portions, the remaining second portions forming fourth portions not being exposed to the second UV radiation.
12 . The method of claim 11 , wherein the third portions cover sidewalls of the fourth portions.
13 . The method of claim 11 , wherein developing the photoresist layer comprises removing top portions of the resin to expose the third portions, and removing the third portions.
14 . The method of claim 7 , further comprising performing a pattern transfer etch using the sub-resolution features as an anti-spacer.
15 . A method of forming sub-resolution features, the method comprising:
loading a substrate in a lithography tool, the substrate comprising a photoresist layer formed thereon;
generating, in the lithography tool, a first ultraviolet light (UV) radiation having a first wavelength of 365 nm or longer;
exposing the photoresist layer to the first UV radiation through a single mask, the photoresist layer comprising first reacted portions exposed to the first UV radiation and first unreacted portions unexposed to the first UV radiation after exposing with the first UV radiation, the first unreacted portions having a first height and a first critical dimension;
generating, in the lithography tool, a second UV radiation having a second wavelength;
exposing the photoresist layer to the second UV radiation, the second UV radiation being a blanket radiation with no pattern, the exposing forming, from the first unreacted portions, second reacted portions exposed to the second UV radiation and second unreacted portions unexposed to the second UV radiation after exposing with the second UV radiation, the second unreacted portions having a second height and a second critical dimension less than the first critical dimension, the second height being less than the first height, wherein exposing to the second UV radiation is performed using a pixel-based projection system having an array of independently addressable projection points; and
forming a plurality of features, the forming comprising developing the photoresist layer after exposing the photoresist layer to the second UV radiation, the developing removing the first reacted portions and the second reacted portions while retaining the second unreacted portions to form the plurality of features.
16 . The method of claim 15 , further comprising spacer patterning, the spacer patterning comprising:
depositing a layer of a spacer material over the plurality of features;
performing a spacer etch back to remove a lateral portion of the spacer material;
performing a pull etch to remove the plurality of features and form a spacer pattern; and
performing a pattern transfer etch using the spacer pattern as an etch mask.
17 . The method of claim 15 , further comprising, before developing, performing a post-exposure bake by thermally treating the substrate.
18 . The method of claim 15 , wherein the plurality of have a width between 200 nm and 360 nm, a height between 20 nm and 900 nm, or a ratio of height to width between 3 and 100.
19 . The method of claim 15 , wherein the first wavelength is 365 nm and the second wavelength is 266 nm.