Method and system for dry etching a metal nitride
A method and system of etching a metal nitride, such as titanium nitride, is described. The etching process comprises introducing a process composition having a halogen containing gas, such as Cl 2 , HBr, or BCl 3 , and a fluorocarbon gas having the chemical formula C x H y F z , where x and z are equal to unity or greater and y is equal to 0 or greater.
1. A method of etching a metal containing layer on a substrate, comprising:
disposing said substrate having a metal nitride layer in a plasma processing system;
elevating the temperature of said substrate above approximately 30 degrees C.;
introducing a process composition consisting of a halogen-containing gas, a fluorocarbon gas, and an optional noble gas to said plasma processing system, wherein said halogen-containing gas consists of BCl 3 or Cl 2 and said fluorocarbon gas consists of CHF 3 ;
forming a plasma from said process composition in said plasma processing system; and
exposing said substrate to said plasma in order to etch said metal nitride layer.
2. The method of claim 1 , wherein said disposing comprises disposing a substrate having a titanium nitride layer.
3. The method of claim 1 , wherein said disposing comprises disposing a substrate having a hafnium containing layer underlying said metal nitride layer.
4. The method of claim 3 , wherein said disposing a substrate having a hafnium containing layer comprises disposing a substrate having a SiO 2 layer underlying said hafnium containing layer.
5. The method of claim 1 , wherein said disposing comprises disposing a substrate having a polysilicon layer overlying said metal nitride layer.
6. The method of claim 5 , wherein said introducing said process composition consists of introducing a flow rate of BCl 3 and a flow rate of CHF 3 , and wherein a ratio between the flow rate of said BCl 3 and the total flow rate of said BCl 3 and said CHF 3 ranges from approximately 50% to approximately 95%.
7. The method of claim 5 , wherein said introducing said process composition consists of introducing a flow rate of BCl 3 and a flow rate of CHF 3 , and wherein a ratio between the flow rate of said BCl 3 and the total flow rate of said BCl 3 and said CHF 3 ranges from approximately 75% to approximately 85%.
8. The method of claim 5 , wherein said introducing said process composition consists of introducing BCl 3 and CHF 3 , and wherein exposing said substrate to said plasma to facilitate said pattern etching comprises achieving an etch selectivity between said metal nitride layer and said poly-crystalline silicon layer greater than or equal to approximately 3-to-1.
9. The method of claim 5 , wherein said introducing said process composition consists of introducing a flow rate of Cl 2 and a flow rate of CHF 3 .
10. The method of claim 9 , wherein a ratio between the flow rate of said Cl 2 and the total flow rate of said Cl 2 and said CHF 3 ranges from approximately 50% to approximately 95%.
11. The method of claim 9 , wherein a ratio between the flow rate of said Cl 2 and the total flow rate of said Cl 2 and said CHF 3 ranges from approximately 75% to approximately 85%.
12. The method of claim 1 , wherein said elevating comprises elevating the temperature to approximately 50 degrees C. and greater.
13. The method of claim 1 , wherein said forming said plasma comprises capacitively coupling power to said plasma, or inductively coupling power to said plasma, or both.
14. The method of claim 1 , wherein said forming said plasma comprises coupling radio frequency (RF) power to a substrate holder upon which said substrate rests.
15. The method of claim 1 , wherein said forming said plasma comprises coupling radio frequency (RF) power to an electrode positioned opposite a substrate holder upon which said substrate rests.
16. The method of claim 1 , wherein the substrate includes a mask layer defining a pattern therein overlaying said metal nitride layer and said exposing etches said pattern into said metal nitride layer.