Apparatus and methods for selectively etching films

Abstract

An apparatus and methods for selectively etching a particular layer are disclosed. The apparatus and methods are directed towards maintaining the etch rate of the particular layer, while keeping intact a non-etched layer. The etching process may be accomplished by co-flowing a hydrogen precursor gas and a fluorine precursor gas into a remote plasma unit. A resulting gas mixture may then be flowed onto the substrate having a silicon oxide layer as an etch layer and a silicon nitride layer as a non-etched layer, for example. A reaction between the resulting gas mixture and the particular layer takes place, resulting in etching of the silicon oxide layer while maintaining the silicon nitride layer in the above example.

1 . A system for selectively etching a film disposed on a substrate, the system comprising:
 a reaction chamber configured to hold and process a substrate, the substrate having a first layer and a second layer disposed thereon;   a remote plasma unit coupled to the reaction chamber;   a fluorine precursor gas source configured to provide a fluorine precursor gas to the remote plasma unit, the fluorine precursor gas comprising at least one of: nitrogen trifluoride (NF 3 ); carbon tetrafluoride (CF 4 ); sulfur hexafluoride (SF 6 ); hydrogen fluoride (HF); hydrofluoric acid (HF) with water vapor; or fluorine (F 2 );   a hydrogen precursor gas source configured to provide a hydrogen precursor gas to the remote plasma unit, the hydrogen precursor gas comprising at least one of: hydrogen (H 2 ); hydrogen fluoride (HF); hydrogen chloride (HCl); or water (H 2 O); and   an inert gas source configured to provide an inert gas to the remote plasma unit, wherein the inert gas is ignited to form a plasma in the remote plasma unit;   wherein the system is configured to form a gaseous mixture from the fluorine precursor and the hydrogen precursor and etch the first layer while maintaining intact the second layer.   
     
     
         2 . The system of  claim 1 , further comprising:
 an ammonia precursor gas source configured to provide an ammonia precursor gas to the reaction chamber.   
     
     
         3 . The system of  claim 2 , wherein the ammonia precursor gas comprises at least one of:
 ammonia (NH 3 ); hydrazine (N 2 H 4 ); or urea (NH 2 CONH 2 ).   
     
     
         4 . The system of  claim 2 , wherein the ammonia precursor gas source is disposed in the system such that the ammonia precursor gas is provided between the remote plasma unit and the reaction chamber. 
     
     
         5 . The system of  claim 1 , wherein the first layer comprises at least one of: silicon oxide; germanium oxide; aluminum oxide; cobalt oxide; tungsten oxide; silicon; germanium; aluminum; cobalt; tungsten; or alloys of various metals. 
     
     
         6 . The system of  claim 1 , wherein the second layer comprises at least one of: silicon nitride; metal nitride; or aluminum nitride. 
     
     
         7 . The system of  claim 1 , wherein the inert gas comprises at least one of: argon; krypton; helium; xenon; or nitrogen. 
     
     
         8 . A method of using the system of  claim 1  to selectively etch a film disposed on a substrate. 
     
     
         9 . A system for selectively etching a film disposed on a substrate, the system comprising:
 a reaction chamber configured to hold and process a substrate, the substrate having a first layer and a second layer disposed thereon;   a first remote plasma unit coupled to the reaction chamber;   a second remote plasma unit coupled to the reaction chamber;   a fluorine precursor gas source configured to provide a fluorine precursor gas to the first remote plasma unit, the fluorine precursor gas comprising at least one of: nitrogen trifluoride (NF 3 ); carbon tetrafluoride (CF 4 ); sulfur hexafluoride (SF 6 ); hydrogen fluoride (HF); hydrofluoric acid (HF) with water vapor; or fluorine (F 2 );   a hydrogen precursor gas source configured to provide a hydrogen precursor gas to the second remote plasma unit, the hydrogen precursor gas comprising at least one of: hydrogen (H 2 ); hydrogen fluoride (HF); hydrogen chloride (HCl); or water (H 2 O); and   an inert gas source configured to provide an inert gas to at least one of the first remote plasma unit or the second remote plasma unit, wherein the inert gas is ignited to form a plasma in at least one of the first remote plasma unit or the second remote plasma unit;   wherein the system is configured to form a gaseous mixture from the fluorine precursor and the hydrogen precursor and etch the first layer while maintaining intact the second layer.   
     
     
         10 . The system of  claim 9 , further comprising:
 an ammonia precursor gas source configured to provide an ammonia precursor gas to the reaction chamber.   
     
     
         11 . The system of  claim 10 , wherein the ammonia precursor gas comprises at least one of:
 ammonia (NH 3 ); hydrazine (N 2 H 4 ); or urea (NH 2 CONH 2 ).   
     
     
         12 . The system of  claim 10 , wherein the ammonia precursor gas source is disposed in the system such that the ammonia precursor gas is provided between (1) the first and second remote plasma units and (2) the reaction chamber. 
     
     
         13 . The system of  claim 9 , wherein the first layer comprises at least one of: silicon oxide; germanium oxide; aluminum oxide; cobalt oxide; tungsten oxide; silicon; germanium; aluminum; cobalt; tungsten; or alloys of various metals. 
     
     
         14 . The system of  claim 9 , wherein the second layer comprises at least one of: silicon nitride; metal nitride; or aluminum nitride. 
     
     
         15 . The system of  claim 9 , wherein the inert gas comprises at least one of: argon; krypton; helium; xenon; or nitrogen. 
     
     
         16 . A method of using the system of  claim 9  to selectively etch a film disposed on a substrate.