Negative tone photoresist for euv lithography

Abstract

A negative tone photoresist and method for developing the negative tone photoresist is disclosed. For example, the negative tone photoresist includes a solvent, a dissolution inhibitor, and a polymer. The polymer includes a hydroxyl group. The polymer may be greater than 40 weight percent of a total weight of the negative tone photoresist.

What is claimed is: 
     
         1 . A method for developing a negative tone photoresist, comprising:
 depositing the negative tone photoresist on a substrate;   exposing a portion of the negative tone photoresist to a radiation source at a power of approximately 20 milli-Joules to 30 milli-Joules; and   developing the negative tone photoresist with an organic solvent, such that the portion of the negative tone photoresist that is exposed remains and unexposed portions of the negative tone photoresist are removed.   
     
     
         2 . The method of  claim 1 , wherein the organic solvent comprises at least one of: tetra methylammonium hydroxide, butyl acetate, or a mixture of 70 percent glycol monomethylether and 30 percent propylene glycol monomethylether acetate. 
     
     
         3 . The method of  claim 1 , wherein the negative tone photoresist comprises a polymer comprising a hydroxyl group, wherein the polymer comprises greater than 40 weight percent (wt %) of a total solid weight of the negative tone photoresist. 
     
     
         4 . The method of  claim 3 , wherein the polymer comprises at least one of: poly hydroxystyrene, poly benzoic acid, or poly acrylic acid. 
     
     
         5 . The method of  claim 3 , wherein the negative tone photoresist comprises a dissolution inhibitor, wherein the dissolution inhibitor comprises greater than 5 wt % of the total solid weight of the negative tone photoresist. 
     
     
         6 . The method of  claim 5 , wherein the dissolution inhibitor comprises at least one of: an epoxy group, a hydroxy-group, a melamine group, or an alkene group. 
     
     
         7 . A lithography method, comprising:
 spin-on coating a negative tone photoresist onto a target layer on a substrate, the negative tone photoresist comprising a polymer including an acid labile group (ALG) and being greater than 40 weight percent (wt %) of a total solid weight of the negative tone photoresist;   applying an EUV radiation source to expose a portion of the negative tone photoresist;   applying a developer to the negative tone photoresist to remove an unexposed portion of the negative tone photoresist, while leaving the exposed portion of the negative tone photoresist on the target layer; and   etching the target layer using the exposed portion of the negative tone photoresist as an etch mask.   
     
     
         8 . The method of  claim 7 , wherein the polymer is 40 wt % to 60 wt % of the total solid weight of the negative tone photoresist. 
     
     
         9 . The method of  claim 7 , further comprising:
 forming an anti-reflective coating (ARC) layer on the target layer prior to spin-on coating the negative tone photoresist.   
     
     
         10 . The method of  claim 9 , wherein the ARC layer includes silicon oxide (SiO 2 ), silicon oxygen carbide (SOC), or plasma enhanced chemical vapor deposited silicon oxide (PECVD-SiO 2 ). 
     
     
         11 . The method of  claim 7 , wherein applying the EUV radiation source is performed such that the negative tone photoresist creates an acid and a hydroxyl radical from the polymer. 
     
     
         12 . The method of  claim 11 , wherein the negative tone photoresist further comprises:
 polyethylene glycol (PEG); and   a solvent including 2-methoxy-1-methylethyl acetate (PGMEA), butyl acetate, ethyl lactate, or a combination thereof, wherein the polymer and the PEG are dissolved in the solvent.   
     
     
         13 . The method of  claim 12 , wherein the negative tone photoresist further comprises:
 a basic quencher dissolved in the solvent, wherein the acid is neutralized by the basic quencher during applying the EUV radiation source.   
     
     
         14 . The method of  claim 12 , wherein the negative tone photoresist further comprises:
 a cross-linking unit dissolved in the solvent.   
     
     
         15 . A lithography method, comprising:
 spin-on coating a photoresist onto a material layer on a substrate, wherein the photoresist includes a cross-linking unit including an epoxy group, a melamine group, or a hydroxy group, and a polymer with an acid labile group (ALG) or a hydroxyl group;   exposing an image of a mask onto the photoresist by using a radiation energy of less than 40 milli-Joules to form hydroxyl radicals from the polymer, such that the cross-linking unit reacts with the hydroxyl radicals to form a cross-linked compound;   developing the photoresist to form a resist pattern; and   etching the material layer using the resist pattern as an etch mask.   
     
     
         16 . The method of  claim 15 , wherein the cross-linking unit is 5 weight percent (wt %) to 10 wt % of a total solid weight of the photoresist. 
     
     
         17 . The method of  claim 15 , wherein the cross-linking unit is greater than 5 weight percent (wt %) of a total solid weight of the photoresist. 
     
     
         18 . The method of  claim 15 , wherein a weight percentage of the polymer of a total solid weight of the photoresist is greater than a weight percentage of the cross-linking unit of the total solid weight of the photoresist. 
     
     
         19 . The method of  claim 15 , wherein the radiation energy is a radiation beam having a wavelength in an EUV range. 
     
     
         20 . The method of  claim 15 , wherein the polymer is selected from a group consisting of poly hydroxystyrene (PHS), poly benzoic acid (PBA), and poly acrylic acid (PAA).