Organic anti-reflective coatings deposited by chemical vapor deposition (CVD)

Abstract

An improved method for applying organic anti-reflective coatings to substrate surfaces and the resulting precursor structures are provided. Broadly, the methods comprise chemical vapor depositing (CVD) a polymer on the substrate surface. In one embodiment, the polymer are formed of highly strained monomers (e.g., monomers having a strain energy of at least about 10 kcal/mol) which themselves comprise two cyclic moieties joined to one another via an alkyl chain. One preferred such monomer is 1,4-dixylylene. The CVD processes comprise heating the monomer so as to vaporize the monomer and then pyrolizing the monomer in the resulting vapor to form stable diradicals which are subsequently polymerized on a substrate surface in a deposition chamber. The inventive methods are useful for providing highly conformal anti-reflective coatings on large substrate surfaces having super submicron (0.25 μm or smaller) features.

We claim:  
     
         1 . A method of forming a precursor for use in manufacturing integrated circuits comprising the steps of: 
 providing a quantity of an anti-reflective compound and a substrate having a surface onto which said compound is to be applied;    subjecting said anti-reflective compound to a chemical vapor deposition process so as to deposit said anti-reflective compound in a layer on said substrate surface; and    applying a photoresist layer to said anti-reflective compound layer to yield the circuit precursor.    
     
     
         2 . The method of  claim 1 , wherein said anti-reflective compound comprises a polymer including a monomer comprising two cyclic moieties joined together by at least one alkyl group, wherein said alkyl group comprises from about 2-4 carbon atoms.  
     
     
         3 . The method of  claim 2 , wherein at least one of said cyclic moieties is aromatic.  
     
     
         4 . The method of  claim 3 , wherein said aromatic moieties are individually selected from the group consisting of benzene, naphthalene, anthracene, thiophene, furan, and pyrrole moieties.  
     
     
         5 . The method of  claim 4 , wherein at least one of said aromatic moieties is benzene.  
     
     
         6 . The method of  claim 5 , wherein said monomer is 1,4-dixylylene.  
     
     
         7 . The method of  claim 2 , wherein said alkyl group is an ethyl group.  
     
     
         8 . The method of  claim 2 , wherein the strain energy of said monomer is at least than about 10 kcal/mol.  
     
     
         9 . The method of  claim 1 , wherein said substrate comprises a silicon wafer.  
     
     
         10 . The method of  claim 2 , wherein said chemical vapor deposition process comprises the steps of: 
 (a) subjecting said monomer to a sufficient temperature and pressure to form said monomer into a vapor;    (b) cleaving the resulting vaporized monomer; and    (c) depositing said cleaved monomer on said substrate surface.    
     
     
         11 . The method of  claim 10 , wherein said subjecting step (a) is carried out at a temperature of from about 35-160° C. and a pressure of from about 2-50 mTorr.  
     
     
         12 . The method of  claim 10 , wherein said cleaving step (b) comprises breaking a bond between two of the carbon atoms of said alkyl group.  
     
     
         13 . The method of  claim 10 , wherein said cleaving step (b) comprises pyrolizing said monomer.  
     
     
         14 . The method of  claim 13 , wherein said pyrolizing step comprises heating said monomer to a temperature of from about 580-700° C.  
     
     
         15 . The method of  claim 10 , wherein said causing step (c) comprises subjecting said cleaved monomer to a temperature of from about 20-25° C.  
     
     
         16 . The method of  claim 1 , wherein the anti-reflective compound layer on said substrate surface after said applying step has a thickness of from about 300-5000 Å.  
     
     
         17 . The method of  claim 1 , wherein said anti-reflective compound layer is substantially insoluble in solvents utilized in said photoresist layer.  
     
     
         18 . The method of  claim 1 , further including the steps of: 
 exposing at least a portion of said photoresist layer to activating radiation;    developing said exposed photoresist layer; and    etching said developed photoresist layer.    
     
     
         19 . The method of  claim 1 , wherein the anti-reflective compound layer deposited on said substrate surface absorbs at least about 90% of light at a wavelength of from about 150-500 nm.  
     
     
         20 . The method of  claim 1 , wherein the anti-reflective compound layer deposited on said substrate surface will be subjected to light of a predetermined wavelength and has a k value of at least about 0.1 at said predetermined wavelength.  
     
     
         21 . The method of  claim 1 , wherein the anti-reflective compound layer deposited on said substrate surface has a percent conformality of at least about 85%.  
     
     
         22 . The method of  claim 21 , wherein said substrate comprises raised features and structure defining contact or via holes, and said subjecting step comprises depositing a quantity of said anti-reflective compound in a layer on said features and said hole-defining structure.  
     
     
         23 . The method of  claim 1 , wherein said anti-reflective compound comprises a polymer including the monomer of Formula II.  
     
     
         24 . A precursor structure formed during the course of the integrated circuit manufacturing process, said structure comprising: 
 a substrate having a surface;    a layer comprising an anti-reflective compound on said surface, said anti-reflective compound layer being formed on said surface by a chemical vapor deposition process; and    a photoresist layer on said anti-reflective compound layer.    
     
     
         25 . The structure of  claim 24 , wherein said anti-reflective compound comprises a polymer including a monomer comprising two cyclic moieties joined together by at least one alkyl group, said alkyl group comprising from 2-4 carbon atoms.  
     
     
         26 . The structure of  claim 25 , wherein at least one of said cyclic moieties is aromatic.  
     
     
         27 . The structure of  claim 26 , wherein said aromatic moieties are individually selected from the group consisting of benzene, naphthalene, anthracene, thiophene, furan, and pyrrole moieties.  
     
     
         28 . The structure of  claim 27 , wherein at least one of said aromatic moieties is benzene.  
     
     
         29 . The structure of  claim 28 , wherein said monomer is 1,4-dixylylene.  
     
     
         30 . The structure of  claim 25 , wherein said alkyl group is an ethyl group.  
     
     
         31 . The structure of  claim 25 , wherein the strain energy of said monomer is at least about 10 kcal/mol.  
     
     
         32 . The structure of  claim 24 , wherein said substrate comprises a silicon wafer.  
     
     
         33 . The structure of  claim 25 , wherein said chemical vapor deposition process by which said anti-reflective compound layer is formed comprises the steps of: 
 (a) subjecting said monomer to a sufficient temperature and pressure to form said monomer into a vapor;    (b) cleaving the resulting vaporized monomer; and    (c) depositing said cleaved monomer on said substrate surface.    
     
     
         34 . The structure of  claim 33 , wherein said subjecting step (a) is carried out at a temperature of from about 35-160° C. and a pressure of from about 2-50 mTorr.  
     
     
         35 . The structure of  claim 33 , wherein said cleaving step (b) comprises breaking a bond between two of the carbon atoms of said alkyl group.  
     
     
         36 . The structure of  claim 33 , wherein said cleaving step (b) comprises pyrolizing said monomer.  
     
     
         37 . The structure of  claim 36 , wherein said pyrolizing step comprises heating said monomer to a temperature of from about 580-700° C.  
     
     
         38 . The structure of  claim 33 , wherein said causing step (c) comprises subjecting said cleaved monomer to a temperature of from about 20-25° C.  
     
     
         39 . The structure of  claim 24 , wherein the anti-reflective compound layer on said substrate surface has a thickness of from about 300-5000 Å.  
     
     
         40 . The structure of  claim 24 , wherein said anti-reflective compound is substantially insoluble in solvents utilized in said photoresist layer.  
     
     
         41 . The structure of  claim 24 , wherein the anti-reflective compound layer deposited on said substrate surface absorbs at least about 90% of light at a wavelength of from about 150-500 nm.  
     
     
         42 . The structure of  claim 24 , wherein the anti-reflective compound layer deposited on said substrate surface will be subjected to light of a predetermined wavelength and has a k value of at least about 0.1 at said predetermined wavelength.  
     
     
         43 . The structure of  claim 24 , wherein the anti-reflective compound layer deposited on said substrate surface has a percent conformality of at least about 85%.  
     
     
         44 . The structure of  claim 43 , wherein said substrate comprises raised features and structure defining contact or via holes and said anti-reflective compound layer is deposited on said features and said hole-defining structure.  
     
     
         45 . The structure of  claim 24 , wherein said anti-reflective compound comprises a polymer including the monomer of Formula II.