Gas phase etch with controllable etch selectivity of metals

1. A method of etching, comprising:

receiving a substrate having a working surface exposing a metal layer and having at least one other material exposed or underneath the metal layer, the metal layer containing W, Ti, TiN, Ta, TaN, Ru, Co, or a transition metal, or combinations thereof; and

differentially etching the metal layer relative to the at least one other material by exposing the substrate to a gas-phase environment containing an anhydrous halogen compound, the differentially etching including

elevating a temperature of the substrate at or above 35 degrees C. and at or below 130 degrees C., when exposed to the anhydrous halogen compound, and

post-heat treating the substrate at a temperature at or above 170 degrees C. after exposing the substrate to the anhydrous halogen compound,

wherein the metal layer contains W, and the at least one other material includes Ti or TiN.

2. The method of claim 1 , wherein the anhydrous halogen compound includes a diatomic halogen, or an interhalogen compound, or a combination thereof.

3. The method of claim 2 , wherein the interhalogen compound includes a tetratomic interhalogen.

4. The method of claim 1 , wherein the anhydrous halogen compound includes F 2 , or ClF 3 , or a combination thereof.

5. The method of claim 1 , wherein the gas-phase environment further includes a nitrogen-containing gas.

6. The method of claim 1 , wherein the gas-phase environment further includes a noble gas element, HF, NF 3 , NH 3 , effluent from a remote plasma source, or combinations of two or more thereof.

7. The method of claim 1 , wherein the at least one other material includes organic material, silicon-containing material, germanium-containing material, or silicon-germanium alloys of the form Si x Ge 1-x , or combinations of two or more thereof, and wherein x is a real number greater than 0.5.

8. The method of claim 7 , wherein the silicon-containing material includes silicon, silicon oxide, silicon nitride, and combinations thereof, and wherein the germanium-containing material includes germanium, germanium oxide, germanium nitride, and combinations thereof.

9. The method of claim 1 , wherein the exposing the substrate to the gas-phase environment containing the anhydrous halogen compound, and the post-heat treating the substrate are performed independently in separate process chambers.

10. The method of claim 1 , wherein the exposing the substrate to the gas-phase environment containing the anhydrous halogen compound, and the post-heat treating the substrate are performed in the same process chamber.

11. A method of etching, comprising:

receiving a substrate having a working surface exposing a metal layer and having at least one other material exposed or underneath the metal layer, the metal layer containing W, Ti, TiN, Ta, TaN, Ru, Co, or a transition metal, or combinations thereof; and

differentially removing at least a portion of the metal layer by performing the following:

(i) exposing the surface of the substrate to a chemical environment containing an anhydrous halogen compound at a first set-point temperature at or above 35 degrees C. to chemically alter a surface region of the metal layer, and

(ii) after the exposing, elevating the temperature of the substrate to a second set-point temperature at or above 170 degrees C. to remove the chemically treated surface region of the metal layer,

the method further comprising: varying the first set-point temperature to alter the etch selectivity between the metal layer and the at least one other material.

12. The method of claim 11 , wherein the anhydrous halogen compound includes a diatomic halogen, or an interhalogen, or a combination thereof.

13. The method of claim 12 , wherein the interhalogen compound includes ClF 3 .

14. A method of etching, comprising:

receiving a substrate having a working surface exposing a metal layer and having at least one other material exposed or underneath the metal layer, the metal layer containing W, Ti, TiN, Ta, TaN, Ru, Co, or a transition metal, or combinations thereof; and

differentially etching the metal layer relative to the at least one other material by exposing the substrate to a gas-phase environment containing an anhydrous halogen compound, the differentially etching including

exposing the substrate to the anhydrous halogen compound with a temperature of the substrate in a range of at or above 35 degrees C. and at or below 130 degrees C., and

after the exposing, increasing temperature of the substrate to perform a post-heat treating of the substrate at a temperature in a range from 100 degrees C. to 300 degrees C.,

the method further including, prior to the differentially etching, exposing the substrate to at least one of NH 3 or HF.

15. The method of claim 14 , wherein the metal layer contains W and the at least one other material includes Ti or TiN.

16. The method of claim 14 , wherein the post-heat treating temperature is in a range from 110 degrees C. to 225 degrees C.