Method of etching a high aspect ratio contact

Abstract

Methods and an etch gas composition for etching a contact opening in a dielectric layer are provided. Embodiments of the method use a plasma generated from an etch gas composed of C 4 F 8 and/or C 4 F 6 , an oxygen source, and a carrier gas in combination with tetrafluoroethane (C 2 F 4 ) or a halofluorocarbon analogue of C 2 F 4 .

1 . An etch gas for etching a dielectric material, the etch gas comprising at least one of C 4 F 6  and C 4 F 8 , an oxygen source, an inert gas, and C 2 F 4 . 
     
     
         2 . The etch gas of  claim 1 , further comprising an additional fluorocarbon gas having the general formula C x F y  where x=1-6 and y=2-8. 
     
     
         3 . The etch gas of  claim 1 , further comprising a hydrofluorocarbon gas having the general formula C x H y F z  where x=1-6, y=1-6 and z=1-6, or a mixture thereof. 
     
     
         4 . An etch gas for plasma etching a dielectric material, the etch gas comprising at least one of C 4 F 6  and C 4 F 8 , an oxygen source, an inert gas, and a halofluorocarbon selected from the group consisting of C 2 F 4 Br 2 , C 2 F 4 I 2  and CF 2 I 2 . 
     
     
         5 . The etch gas of  claim 1 , consisting essentially of the at least one of C 4 F 6  and C 4 F 8 , oxygen source, inert gas, and C 2 F 4 . 
     
     
         6 . The etch gas of  claim 4 , further comprising at least one of an additional fluorocarbon gas having the general formula C x F y  where x=1-6 and y=2-8, and a hydrofluorocarbon gas having the general formula C x H y F z  where x=1-6, y=1-6 and z=1-6. 
     
     
         7 . The etch gas of  claim 1 , wherein the oxygen source comprises oxygen (O 2 ), carbon monoxide (CO), or mixtures thereof. 
     
     
         8 . The etch gas of  claim 1 , wherein the inert gas comprises argon (Ar), xenon (Xe), neon (Ne), krypton (Kr), or helium (He). 
     
     
         9 . The etch gas of  claim 1 , further comprising a stabilizing agent. 
     
     
         10 . The etch gas of  claim 1 , wherein a ratio of C 4 F 8 :C 2 F 4  is from about 0.25:1 to 1.5:1. 
     
     
         11 . The etch gas of  claim 1 , wherein a ratio of C 4 F 6 :C 2 F 4  is from about 0.25:1 to 1.5:1. 
     
     
         12 . An etch gas consisting of at least one of C 4 F 6  and C 4 F 8 , an oxygen source, an inert gas, and C 2 F 4 . 
     
     
         13 . The etch gas of  claim 12 , wherein the etch gas consists of C 4 F 8 , oxygen (O 2 ), Ar, and C 2 F 4 . 
     
     
         14 . The etch gas of  claim 12 , wherein the etch gas consists of C 4 F 6 , oxygen (O 2 ), Ar4 and C 2 F 4 . 
     
     
         15 . The etch gas of  claim 12 , wherein the etch gas consists of C 4 F 8 , C 4 F 6 , oxygen (O 2 ), Ar, and C 2 F 4 . 
     
     
         16 . An etch gas consisting of at least one of C 4 F 6  and C 4 F 8 , an oxygen source, an inert gas, and a source of C 2 F 4 . 
     
     
         17 . The etch gas of  claim 16 , wherein the source of C 2 F 4  comprises at least one of 1,2-dibromo tetrafluoroethane, 1,2-diiodo tetrafluoroethane, and diiodo difluoromethane.