Method of fabricating dual damascene structures using a multilevel multiple exposure patterning scheme

Abstract

A method for fabricating a dual damascene structure includes providing a first photoresist layer coated on an underlying dielectric stack, exposing said first photoresist layer to a first predetermined pattern of light, coating a second photoresist layer onto the pre-exposed first photoresist layer, exposing said second photoresist layer to a second predetermined pattern of light, optionally post-exposure baking the multi-tiered photoresist layers and developing said photoresist layers to form a multi-tiered dual damascene structure in the photoresist layers.

1 . A method comprising:
 providing a first photoresist layer having a first dose-to-clear value;   exposing the first photoresist layer to a first predetermined pattern of light with a first exposure removal dose;   providing a second photoresist layer on top of the first photoresist layer having a second dose-to-clear value that is lower than the first dose-to-clear value of the first photoresist layer;   exposing the second photoresist layer to a second predetermined pattern of light with a second exposure removal dose, the second exposure removal dose being smaller than the first exposure removal dose; and   developing the first photoresist layer and the second photoresist layer to remove is the first developable region in the first photoresist layer and the second developable region in the second photoresist layer, to form a multi-tiered structure in the photo-resist layers.   
     
     
         2 . A method according to  claim 1 , further comprising transferring the multi-tiered structure into an interlayer dielectric layer of the semiconductor substrate, wherein said interlayer dielectric layer is under said second photoresist layer. 
     
     
         3 . A method according to  claim 1 , wherein further comprises a top anti-reflective coating layer and a bottom anti-reflective coating layer. 
     
     
         4 . A method according to  claim 1 , wherein said first and second photoresist layers are immiscible. 
     
     
         5 . A method according to  claim 1 , wherein said photoresists layers are positive-tone resists. 
     
     
         6 . A method according to  claim 1 , wherein said photoresists layers are negative-tone photoresists. 
     
     
         7 . A method according to  claim 1 , wherein said first predetermined pattern of light comprises an image which consists of a via-hole pattern and said second predetermined pattern of light comprises an image which consists of a line-and-space pattern. 
     
     
         8 . A method according to  claim 1 , wherein each of said photoresist layers are sensitive to a same wavelength of light, and said first and second predetermined patterns of light comprise said same wavelength of light. 
     
     
         9 . A method according to  claim 8 , wherein the dose-to-clear ratio between the first dose-to-clear value and the second dose-to-clear value is comprised between about 2.5 to about 4.0. 
     
     
         10 . A method according to  claim 1 , wherein the dose-to-clear ratio between the first dose-to-clear value and the second dose-to-clear value is comprised between about 2.5 to about 4.0. 
     
     
         11 . A method according to  claim 1 , wherein said first photoresist layer is sensitive to a first wavelength of light and said second photoresist layer is sensitive to a second wavelength of light; and
 said first predetermined pattern of light comprise said first wavelength of light and said second predetermined pattern of light comprise said second wavelength of light.   
     
     
         12 . A method according to  claim 11 , further comprising exposing said first photoresist layer to a first predetermined patterns of light and said second photoresist layer to a second predetermined pattern of light, wherein each predetermined pattern of light comprises light of one of said first and sais second wavelengths of light. 
     
     
         13 . A method according to  claim 1 , further comprising providing a first reticle having a plurality of distinct transparency regions, wherein exposing said first photoresist layer comprises passing light through said first reticle to create said first predetermined pattern of light. 
     
     
         14 . A method according to  claim 1 , further comprising providing a second reticle having a plurality of distinct transparency regions, wherein exposing said second photoresist layer comprises passing light through said second reticle to create said second predetermined pattern of light. 
     
     
         15 . A method according to  claim 13 , wherein said first reticle comprises a characteristic selected from the group consisting of one or more of an optical proximity corrected pattern, an assist feature, and a phase shift pattern. 
     
     
         16 . A method according to  claim 14 , wherein said second reticle comprises a characteristic selected from the group consisting of one or more of an optical proximity corrected pattern, an assist feature, and a phase shift pattern. 
     
     
         17 . A method according to  claim 1  further including post-exposure baking the first photoresist layer and the second photoresist layer. 
     
     
         18 . A method for fabricating a dual damascene structure, comprising:
 providing a first photoresist layer having a first dose-to-clear value; exposing the first photoresist layer to a first predetermined pattern of light with a first exposure removal dose;   providing a second photoresist layer on top of the first photoresist layer having a second dose-to-clear value that is lower than the first dose-to-clear value of the first photoresist layer;   exposing the second photoresist layer to a second predetermined pattern of light with a second exposure removal dose, the second exposure removal dose being smaller than the first exposure removal dose;   developing the first photoresist layer and the second photoresist layer to remove the first developable region in the first photoresist layer and the second developable region in the second photoresist layer, to form a multi-tiered structure in the photo-resist layers;
 transferring the multi-tiered structure into an interlayer dielectric layer of the semiconductor substrate, wherein said interlayer dielectric layer is under said second photoresist layer; 
 a top anti-reflective coating layer and a bottom anti-reflective coating layer; 
   said first and second photoresist layers are immiscible;   said photoresists layers are each selected from the group consisting of positive-tone resists and negative-tone photoresists;   said first predetermined pattern of light comprises an image which consists of a via-hole pattern and said second predetermined pattern of light comprises an image which consists of a line-and-space pattern;   wherein each of said photoresist layers are sensitive to a wavelength of light selected from the group consisting of the same or different wavelengths of light, and said first and second predetermined patterns of light comprise said wavelength of light selected from the group consisting of the same or different wavelengths of light;   said first photoresist layer is sensitive to a first wavelength of light and said second photoresist layer is sensitive to a second wavelength of light;   said first predetermined pattern of light comprise said first wavelength of light and said second predetermined pattern of light comprise said second wavelength of light;   providing a first reticle having a plurality of distinct transparency regions, wherein exposing said first photoresist layer comprises passing light through said first reticle to create said first predetermined pattern of light and   providing a second reticle having a plurality of distinct transparency regions, wherein exposing said second photoresist layer comprises passing light through said second reticle to create said second predetermined pattern of light.   
     
     
         19 . A method according to  claim 18 , further comprising exposing said first photoresist layer to a first predetermined patterns of light and said second photoresist layer to a second predetermined pattern of light, wherein each predetermined pattern of light comprises light of one of said first and said second wavelengths of light. 
     
     
         20 . A method according to  claim 18 , wherein said first reticle comprises a characteristic selected from the group consisting of one or more of an optical proximity corrected pattern, an assist feature, and a phase shift pattern. 
     
     
         21 . A method according to  claim 18 , wherein said second reticle comprises a characteristic selected from the group consisting of one or more of an optical proximity corrected pattern, an assist feature, and a phase shift pattern. 
     
     
         22 . A method according to  claim 16  further including post-exposure baking the first photoresist layer and the second photoresist layer. 
     
     
         23 . A method according to  claim 17  further including post-exposure baking the first photoresist layer and the second photoresist layer. 
     
     
         24 . A method according to  claim 18  further including post-exposure baking the first photoresist layer and the second photoresist layer. 
     
     
         25 . A method according to  claim 19  further including post-exposure baking the first photoresist layer and the second photoresist layer. 
     
     
         26 . A method according to  claim 1  wherein said method is for fabricating a dual damascene structure. 
     
     
         27 . A structure, comprising: a first dielectric layer having a first dose-to-clear value; a second dielectric layer having a second dose-to-clear value that is different than the first dose-to-clear value of the first dielectric layer. 
     
     
         28 . A structure according to  claim 27  wherein said second dose-to-clear value is lower than the said first dose-to-clear value. 
     
     
         29 . A structure according to  claim 27  wherein there is a pattern in said first dielectric layer and said second dielectric layer that is filled with an electrical conductor. 
     
     
         30 . A structure according to  claim 29  wherein there is a pattern in said first dielectric layer and said second dielectric layer that is filled with an electrical conductor. 
     
     
         31 . A structure according to  claim 27  wherein said structure is a dual damascene structure. 
     
     
         32 . A structure according to  claim 27  wherein said second dielectric layer is disposed adjacent to said first dielectric layer. 
     
     
         33 . A structure according to  claim 29  wherein said pattern comprises a first pattern in said first dielectric layer and a second pattern in said second dielectric layer 
     
     
         34 . A structure according to  claim 33  wherein said first patter and said second pattern are selected from the group consisting of not being geometrically coincident and not having the same dimensions. 
     
     
         35 . A structure according to  claim 27 , wherein the dose-to-clear ratio between the first dose-to-clear value and the second dose-to-clear value is comprised between about 2.5 to about 4.0. 
     
     
         36 . A method comprising: providing in a structure a first dielectric layer having a first dose-to-clear value; providing in said structure a second dielectric layer having a second dose-to-clear value that is different than the first dose-to-clear value of the first dielectric layer. 
     
     
         37 . A method according to  claim 36  wherein said second dose-to-clear value is lower than the said first dose-to-clear value. 
     
     
         38 . A method according to  claim 36  wherein there is a pattern in said first dielectric layer and said second dielectric layer that is filled with an electrical conductor. 
     
     
         39 . A method according to  claim 37  wherein there is a pattern in said first dielectric layer and said second dielectric layer that is filled with an electrical conductor. 
     
     
         40 . A method according to  claim 36  wherein said first dielectric layer is disposed in contact with said second dielectric layer. 
     
     
         41 . A method according to  claim 36  wherein said structure is a dual damascene structure. 
     
     
         42 . A method according to  claim 39  wherein said pattern comprises a first pattern in said first dielectric layer and a second pattern in said second dielectric layer 
     
     
         43 . A method according to  claim 42  wherein said first patter and said second pattern are selected from the group consisting of not being geometrically coincident and not having the same dimensions. 
     
     
         44 . A method according to  claim 36 , wherein the dose-to-clear ratio between the first dose-to-clear value and the second dose-to-clear value is comprised between about 2.5 to about 4.0.