Method and system for dry etching a hafnium containing material

1. A method of etching a gate stack on a substrate, said gate stack including a silicon dioxide layer, a hafnium containing layer including HfO 2 and a poly-crystalline silicon layer, the method comprising:

disposing said substrate having said gate stack, said gate stack including said silicon dioxide layer, said hafnium containing layer including HfO 2 and said poly-crystalline silicon layer in a plasma processing system, wherein a mask layer defining a pattern therein overlies said gate stack;

elevating the temperature of said substrate above approximately 30 degrees C.;

introducing a process composition comprising BCl 3 and an additive gas to said plasma processing system, the additive gas comprising an oxygen-containing gas, a nitrogen containing gas, or a hydrocarbon gas characterized by C x H y , wherein x and y are integers greater than or equal to unity, or a combination of two or more thereof;

adjusting the flow rates of BCl 3 and the additive gas to a predetermined level for achieving an etch selectivity between said hafnium containing layer and said poly-crystalline silicon layer on the substrate of greater than or equal to approximately 10-to-1, and at the same predetermined level achieving an etch selectivity between said hafnium containing layer and said SiO 2 layer on the substrate of greater than or equal to approximately 10-to-1;

forming a plasma from said process composition in said plasma processing system; and

exposing said substrate to said plasma in order to etch said pattern into said hafnium containing layer while simultaneously suppressing etching of the poly-crystalline silicon layer and the silicon dioxide layer.

2. The method of claim 1 , wherein said introducing said process composition further comprises introducing an inert gas.

3. The method of claim 2 , wherein said introducing said inert gas comprises introducing a noble gas.

4. The method of claim 1 , wherein said introducing said additive gas comprises introducing an oxygen containing gas comprising O 2 , NO, NO 2 , N 2 O, CO, or CO 2 , or a combination of two or more thereof.

5. The method of claim 1 , wherein said introducing said additive gas comprises introducing a nitrogen containing gas comprising N 2 , or NH 3 , or a combination of two or more thereof.

6. The method of claim 1 , wherein said introducing said additive gas comprises introducing a hydrocarbon gas comprising C 2 H 4 , CH 4 , C 2 H 2 , C 2 H 6 , C 3 H 4 , C 3 H 6 , C 3 H 8 , C 4 H 6 , C 4 H 8 , C 4 H 10 , C 5 H 8 , C 5 H 10 , C 6 H 6 , C 6 H 10 , or C 6 H 12 , or two or more thereof.

7. The method of claim 1 , wherein said introducing said additive gas comprises introducing CH 4 .

8. The method of claim 1 , wherein said introducing said additive gas comprises introducing CH 4 and N 2 .

9. The method of claim 1 , wherein said elevating the temperature of said substrate comprises elevating the temperature to approximately 50 degrees C. and greater.

10. The method of claim 1 , wherein exposing said substrate to said plasma comprises achieving an etch selectivity between said hafnium containing layer and said poly-crystalline silicon layer greater than or equal to approximately 10-to-1, and achieving an etch selectivity between said hafnium containing layer and said SiO 2 layer greater than or equal to approximately 30-to-1.

11. 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 a combination of two or more thereof.

12. 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.

13. The method of claim 12 , further comprising adjusting a power level of said RF power to a predetermined level in order to achieve said etch selectivity between said hafnium containing layer and said poly-crystalline silicon layer greater than or equal to approximately 10-to-1, and said etch selectivity between said hafnium containing layer and said SiO 2 layer greater than or equal to approximately 10-to-1.

14. The method of claim 13 , wherein the power on the substrate holder is between approximately 10 W and approximately 50 W.

15. The method of claim 14 , wherein the flow rate of BCl 3 is 100 sccm and the power on the lower electrode is 22 W.

16. The method of claim 14 , wherein the flow rate of BCl 3 is 190 sccm and the power on the lower electrode is 30 W.

17. 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.

18. The method of claim 1 , wherein said elevating the temperature of said substrate comprises elevating the temperature to approximately 75 degrees C. and greater.

19. The method of claim 1 , wherein said elevating the temperature of said substrate comprises elevating the temperature to approximately 100 degrees C. and greater.

20. The method of claim 1 , wherein said elevating the temperature of said substrate comprises elevating the temperature to approximately 200 degrees C.