Plasma etching of silicon carbide

Abstract

A process for plasma etching silicon carbide with selectivity to an overlying and/or underlying dielectric layer of material. The dielectric material can comprise silicon dioxide, silicon oxynitride, silicon nitride or various low-k dielectric materials including organic low-k materials. The etching gas includes a chlorine containing gas such as Cl 2 , an oxygen containing gas such as O 2 , and a carrier gas such as Ar. In order to achieve a desired selectivity to such dielectric materials, the plasma etch gas chemistry is selected to achieve a desired etch rate of the silicon carbide while etching the dielectric material at a slower rate. The process can be used to selectively etch a hydrogenated silicon carbide etch stop layer or silicon carbide substrate.

What is claimed is:  
     
         1 . A method of plasma etching a layer of silicon carbide with selectivity to underlying and/or overlying dielectric material, the method comprising: 
 positioning a semiconductor substrate in a reactor chamber, the substrate including a layer of silicon carbide and an underlying and/or overlying layer of dielectric material;    supplying an etchant gas to the chamber, the etchant gas comprising a chlorine containing gas, an oxygen containing gas, and optional carrier gas; and    energizing the etchant gas into a plasma state and etching openings in the silicon carbide layer, the silicon carbide layer being etched at a faster rate than the dielectric material.    
     
     
         2 . The method of  claim 1 , wherein the oxygen containing gas is O 2 , CO, or CO 2  and the chlorine containing gas is Cl 2  or BCl 3 .  
     
     
         3 . The method of  claim 1 , wherein the carrier gas is He, Ne, Ar, Kr, or Xe.  
     
     
         4 . The method of  claim 1 , wherein the chlorine containing gas and the oxygen containing gases are supplied to the reactor chamber at a flow rate ratio of at least 2:1.  
     
     
         5 . The method of  claim 1 , wherein the chlorine containing gas is Cl 2  and the oxygen containing gas is O 2 .  
     
     
         6 . The method of  claim 1 , wherein the chlorine containing gas is supplied to the reactor chamber at a rate of 5 to 50 sccm.  
     
     
         7 . The method of  claim 6 , wherein the oxygen containing gas is supplied to the reactor chamber at a rate of 2 to 25 sccm.  
     
     
         8 . The method of  claim 1 , wherein the carrier gas is supplied to the reactor chamber at a rate of 10 to 400 sccm.  
     
     
         9 . The method of  claim 8 , wherein the carrier gas is supplied to the reactor chamber at a rate of 25 to 100 sccm.  
     
     
         10 . The method of  claim 1 , wherein the silicon carbide is etched with an etch rate selectivity to an overlying silicon oxide mask layer of at least 10 and/or an etch rate selectivity to an underlying low-k dielectric layer of at least 5.  
     
     
         11 . The method of  claim 1 , wherein the silicon carbide etch rate is at least 1200 Å/min.  
     
     
         12 . The method of  claim 1 , wherein the substrate includes a patterned silicon dioxide hard mask and layer of low-k dielectric above the silicon carbide layer, the low-k dielectric having been previously etched to expose the silicon carbide layer at locations corresponding to openings in the hard mask, the silicon carbide comprising an etch stop layer etched with an etch rate selectivity to the hard mask of at least 5.  
     
     
         13 . The method of  claim 12 , wherein the substrate further includes a layer of low-k dielectric below the silicon carbide layer.  
     
     
         14 . The method of  claim 13 , wherein the low-k dielectric material comprises an organic polymer material and the silicon carbide comprises hydrogenated silicon carbide.  
     
     
         15 . The method of  claim 1 , wherein a silicon carbide:dielectric etch rate selectivity ratio is at least 10.  
     
     
         16 . The method of  claim 1 , wherein the reactor chamber comprises an ECR plasma reactor, an inductively coupled plasma reactor, a capacitively coupled reactor, a helicon plasma reactor or a magnetron plasma reactor.  
     
     
         17 . The method of  claim 1 , wherein the openings comprise vias, contacts, and/or trenches.  
     
     
         18 . The method of  claim 1 , wherein the openings are in a single or dual damascene structure.  
     
     
         19 . The method of  claim 1 , wherein the chamber pressure in the reactor chamber is 5 to 500 mTorr.  
     
     
         20 . The method of  claim 1 , wherein the silicon carbide layer comprises an upper portion of a silicon carbide substrate.