Increasing masking layer etch rate and selectivity

Abstract

Provided is a method and system for increasing etch rate and etch selectivity of a masking layer on a substrate, wherein the system comprises a plurality of substrates containing the masking layer and a layer of silicon or silicon oxide, an etch processing chamber configured to process the plurality of substrates, the processing chamber containing a treatment liquid for etching the masking layer, and a boiling apparatus coupled to the processing chamber and configured to generate a supply of steam water vapor mixture at elevated pressure, wherein the steam water vapor mixture is introduced into the processing chamber at a controlled rate to maintain a selected target etch rate and a target etch selectivity ratio of the masking layer to silicon or silicon oxide.

1 . A system for increasing etch rate and etch selectivity of a masking layer on a substrate, the system comprising:
 a plurality of substrates containing the masking layer and a layer of silicon or silicon oxide;   an etch processing chamber configured to process the plurality of substrates, the etch processing chamber containing a treatment liquid for etching the masking layer in the plurality of substrates; and   a boiling apparatus coupled to the processing chamber and configured to generate a supply of steam water vapor mixture at elevated pressure;   wherein the steam water vapor mixture is introduced into the etch processing chamber at a flow rate sufficient to maintain a selected target etch rate and a selected target etch selectivity ratio of the masking layer to silicon or silicon oxide.   
     
     
         2 . The system of  claim 1 , where the masking layer comprises one of silicon nitride, gallium nitride, or aluminum nitride. 
     
     
         3 . The system of  claim 2 , wherein the treatment liquid is an aqueous phosphoric acid solution. 
     
     
         4 . The system of  claim 2 , wherein the selected target etch selectivity ratio is in the range from 10:1 to 1000:1. 
     
     
         5 . The system of  claim 3 , wherein a temperature of the aqueous phosphoric acid solution is in the range of 160 to 220 degrees Centigrade. 
     
     
         6 . The system of  claim 2 , wherein the steam water vapor mixture at elevated pressure and a treatment liquid are combined at high pressure prior to entering the etch processing chamber. 
     
     
         7 . The system of  claim 2 , wherein the steam water vapor mixture at elevated pressure and a treatment liquid are combined at high pressure prior to exiting supply delivery lines to the etch processing chamber. 
     
     
         8 . The system of  claim 2 , wherein:
 the flow rate and pressure of the steam water vapor mixture are controlled to maintain the selected target etch rate and the selected target etch selectivity ratio of silicon nitride to silicon or silicon oxide.   
     
     
         9 . The system of  claim 1 , wherein:
 the steam water vapor mixture at elevated pressure is introduced into the etch processing chamber using nozzles fitted along a bottom and a side of the etch processing chamber; and   the steam water vapor mixture is introduced at a controlled rate to maintain the selected target etch rate and the selected target etch selectivity ratio of the masking layer to silicon or silicon oxide.   
     
     
         10 . The system of  claim 1 , wherein the treatment liquid includes one of phosphoric acid, hydrofluoric acid, or hydrofluoric acid/ethylene glycol. 
     
     
         11 . The system of  claim 1  wherein the flow rate and pressure of the steam water vapor mixture are controlled to cause a temperature of the treatment liquid, causing in turn a boiling point temperature of the treatment liquid and further causing an equilibrium concentration and temperature of the treatment liquid to achieve the target etch rate and the target etch selectivity ratio. 
     
     
         12 . A method of increasing etch rate and etch selectivity of a masking layer on a substrate, the method comprising:
 fabricating a plurality of substrates containing the masking layer and a layer of silicon or silicon oxide;   obtaining a supply of steam water vapor mixture at an elevated pressure;   obtaining a supply of a treatment liquid for selectively etching the masking layer over the silicon or silicon oxide at a set etch rate and a set etch selectivity ratio;   placing the plurality of substrates into an etch processing chamber;   combining the treatment liquid and the steam water vapor mixture; and   injecting the combined treatment liquid and the steam water vapor mixture into the etch processing chamber;   wherein a flow of the combined treatment liquid and the steam water vapor mixture is configured to maintain the set etch rate and the set etch selectivity ratio of the masking layer to silicon or silicon oxide.   
     
     
         13 . The method of  claim 12 , where the masking layer comprises silicon nitride. 
     
     
         14 . The method of  claim 13 , wherein the treatment liquid comprises an aqueous phosphoric acid solution. 
     
     
         15 . The method of  claim 13 , wherein the set etch selectivity ratio is from 10:1 to 1000:1. 
     
     
         16 . The method of  claim 13 , wherein a temperature of the aqueous phosphoric acid solution is in the range of 160 to 180 degrees Centigrade. 
     
     
         17 . The method of  claim 13 , wherein the steam water vapor mixture at elevated pressure and the treatment liquid are combined at high pressure prior to entering the etch processing chamber. 
     
     
         18 . The method of  claim 13 , wherein:
 the injecting the combined treatment liquid and the steam water vapor mixture uses nozzles fitted along a bottom and/or sides of the etch processing chamber; and   the steam water vapor mixture is introduced at a controlled rate to maintain the set etch selectivity ratio of silicon nitride to silicon or silicon oxide.   
     
     
         19 . The method of  claim 13 , wherein the treatment liquid includes one of phosphoric acid, hydrofluoric acid, or hydrofluoric acid/ethylene glycol. 
     
     
         20 . The method of  claim 19 , wherein the masking layer includes one of silicon nitride, gallium nitride, or aluminum nitride. 
     
     
         21 . The method of  claim 20  wherein flow rate and pressure of the steam water vapor mixture are controlled to cause a temperature of the treatment liquid, causing in turn a boiling point temperature of the treatment liquid and further causing an equilibrium concentration and temperature of the treatment liquid to achieve the target etch rate and the target etch selectivity ratio. 
     
     
         22 . A method of increasing etch rate and selectivity of etching silicon nitride on a substrate, the method comprising:
 placing a plurality of substrates containing a masking layer of silicon nitride and a layer of silicon or silicon oxide into an etch processing chamber;   combining a treatment liquid and a steam water vapor mixture under elevated pressure; and   injecting the combined treatment liquid and the steam water vapor mixture into the etch processing chamber;   wherein a flow of the combined treatment liquid and the steam water vapor mixture are controlled to maintain a target etch rate of the silicon nitride and a target etch selectivity ratio of the silicon nitride to silicon or silicon oxide.   
     
     
         23 . The method of  claim 22 , wherein the treatment liquid includes one of phosphoric acid, hydrofluoric acid, or hydrofluoric acid/ethylene glycol. 
     
     
         24 . The method of  claim 23  wherein a flow rate and pressure of the steam water vapor mixture are controlled to cause a temperature of the treatment liquid, causing in turn a boiling point temperature and further causing an equilibrium concentration and temperature of the treatment liquid to achieve the target etch rate and the target etch selectivity ratio.