Bottom antireflective coating materials
A method according to the present disclosure includes providing a substrate, depositing an underlayer over the substrate, depositing a photoresist layer over the underlayer, exposing a portion of the photoresist layer and a portion of the underlayer to a radiation source according to a pattern, baking the photoresist layer and underlayer, and developing the exposed portion of the photoresist layer to transfer the pattern to the photoresist layer. The underlayer includes a polymer backbone, a polarity switchable group, a cross-linkable group bonded to the polymer backbone, and photoacid generator. The polarity switchable group includes a first end group bonded to the polymer backbone, a second end group including fluorine, and an acid labile group bonded between the first end group and the second end group. The exposing decomposes the photoacid generator to generate an acidity moiety that detaches the second end group from the polymer backbone during the baking.
1 . A method, comprising:
depositing a material layer over a substrate using a solution, wherein the solution comprises:
a polymer backbone,
an acid labile group bonded to the polymer backbone,
an ultraviolet (UV) curable group bonded to the acid labile group,
a thermal acid generator for releasing an acidic moiety when heated to a temperature higher than its threshold temperature, and
a photobase generator for releasing a basic moiety upon exposure to radiation of a predetermined wavelength range,
curing the material layer using UV radiation and activating the UV curable group to form crosslinks;
depositing a negative-tone photoresist layer over the cured material layer;
exposing a portion of the photoresist layer and a portion of the cured material layer disposed under the portion of the photoresist layer to radiation of the predetermined wavelength range;
after the exposing, baking the cured material layer at a temperature higher than the threshold temperature to decompose the thermal acid generator to provide the acidic moiety, wherein the acidic moiety formed in the exposed portion of the material layer is neutralized by the basic moiety, wherein the acidic moiety formed in an unexposed portion of the material layer decomposes the acid labile group in the unexposed portion, thereby decoupling the crosslinks formed by the UV curable group in the unexposed portion; and
developing the exposed portion of the photoresist layer and the exposed portion of the material layer.
2 . The method of claim 1 , further comprising removing the unexposed portion of the material layer and an unexposed portion of the photoresist layer.
3 . The method of claim 1 , wherein during the curing of the material layer, the acid labile group is not sensitive to the UV radiation.
4 . The method of claim 1 , wherein the solution is free of photoacid generators.
5 . The method of claim 1 , wherein the photoresist layer is an organometallic photoresist including tin, zirconium, palladium, cobalt, nickel, chromium, iron, rhodium, or ruthenium.
6 . The method of claim 1 , further comprising:
before the exposing, performing a pre-exposure baking process, wherein a temperature of the pre-exposure baking process is lower than the threshold temperature.
7 . The method of claim 1 , wherein the photoresist layer includes [(SnBu) 12 O 14 (OH) 6 ](OH) 2 .
8 . A method, comprising:
depositing a material layer over a substrate, wherein the material layer comprises:
a polymer backbone,
a light-sensitive group bonded to the polymer backbone by way of an acid labile group,
a thermal acid generator for generating an acidic moiety when heated to a temperature higher than its threshold temperature, and
a photosensitive group for generating a basic moiety upon exposure to radiation of a predetermined wavelength range;
performing a curing process using an exposure to activate the light-sensitive group to form crosslinks within the material layer;
exposing a first portion of the material layer without exposing a second portion of the material layer to a radiation source, wherein the photosensitive group in the radiated exposed first portion of the material layer releases the basic moiety; and
conducting a thermal process to the material layer at a temperature higher than the threshold temperature to decompose the thermal acid generator, wherein the acid labile groups is cleaved in the unexposed second portion but not in the exposed first portion.
9 . The method of claim 8 , further comprising: performing an etching process to selectively remove the second portion of the material layer without substantially etching the first portion of the material layer.
10 . The method of claim 8 , wherein temperature of the thermal process is between about 160° C. and about 250° C.
11 . The method of claim 8 , wherein the acidic moiety in the exposed first portion of the material layer is neutralized by the basic moiety.
12 . The method of claim 8 , wherein the material layer further comprises a polar group directly bonded to the polymer backbone.
13 . The method of claim 8 , further comprising:
before the exposing, forming a photoresist layer over the material layer,
wherein the photoresist layer is an organometallic photoresist comprising a metal selected from a group consisting of tin, palladium, zirconium, cobalt, nickel, chromium, iron, rhodium, and ruthenium.
14 . A method, comprising:
spin-coating a bottom antireflective coating layer over a substrate, wherein the bottom antireflective coating layer comprises a polymer backbone, an acid labile group bonded to the polymer backbone, an ultraviolet (UV) curable group bonded to the acid labile group, a thermal acid generator, and a photobase generator;
performing a first exposure with a first radiation to cure the bottom antireflective coating layer, wherein the UV curable group forms crosslinks;
forming a resist layer over the bottom antireflective coating layer, the resist layer having a first portion and a second portion;
providing a photo mask having a pattern covering the first portion of the resist layer without covering the second portion of the resist layer;
performing a second exposure with a second radiation to the resist layer and the cured bottom antireflective coating layer, wherein the performing of the second radiation forms basic moiety from the photobase generator in a portion of the cured bottom antireflective coating layer disposed directly under the second portion of the resist layer; and
performing a thermal process to the substrate to heat the bottom antireflective coating layer, thereby producing acidic moiety from the thermal acid generator in the bottom antireflective coating layer, wherein the acid labile group is cleaved from the polymer backbone in a portion of the cured bottom antireflective coating layer disposed directly under the first portion of the resist layer.
15 . The method of claim 14 , further comprising:
performing an etching process to selectively remove the first portion of the resist layer and the portion of the cured bottom antireflective coating layer disposed directly under the first portion of the resist layer.
16 . The method of claim 14 , wherein the performing of the second exposure comprises implementing an ArF (argon fluoride) excimer laser radiation source or a KrF (krypton fluoride) excimer laser radiation source.
17 . The method of claim 14 , further comprising performing a pre-exposure bake process before performing the second exposure,
wherein a temperature of the thermal process is higher than a temperature of the pre-exposure bake process.
18 . The method of claim 14 , wherein during the thermal process, the basic moiety reacts with the acidic moiety in the portion of the cured bottom antireflective coating layer disposed directly under the second portion of the resist layer.
19 . The method of claim 14 , wherein during the first exposure, the acid labile group remains intact.
20 . The method of claim 14 , wherein during the thermal process, the acid labile group in the portion of the cured bottom antireflective coating layer disposed directly under the second portion of the resist layer is not cleaved from the polymer backbone.