Selective material removal

1. An etching method comprising:

flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber;

forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor;

flowing the plasma effluents into a processing region of the semiconductor processing chamber, wherein the processing region houses a substrate, wherein the substrate comprises a region of exposed silicon nitride and a region of exposed oxide;

providing a hydrogen-containing precursor into the processing region of the semiconductor processing chamber, wherein the hydrogen-containing precursor comprises one of diatomic hydrogen or hydrogen fluoride, wherein the hydrogen-containing precursor bypasses the remote plasma region when provided to the processing region, and wherein a ratio of a flow rate of the fluorine-containing precursor to a flow rate of the hydrogen-containing precursor ranges between about 1:10 and about 2:1; and

selectively removing at least a portion of the exposed silicon nitride relative to the exposed oxide, wherein an oxygen-containing precursor is not delivered into the semiconductor processing chamber during the etching method.

2. The etching method of claim 1 , wherein the fluorine-containing precursor comprises nitrogen trifluoride.

3. The etching method of claim 1 , wherein a temperature of the substrate is maintained between about 0° C. and about 150° C. during the etching method.

4. The etching method of claim 1 , wherein a pressure within the semiconductor processing chamber is maintained between about 0.5 Torr and about 50 Torr.

5. The etching method of claim 1 , wherein the etching method has a selectivity of silicon nitride to oxide greater than or about 500:1.

6. The etching method of claim 1 , wherein the etching method produces a recessed sidewall of the exposed silicon nitride, and wherein the recessed sidewall has a substantially straight recess profile.

7. The etching method of claim 1 , wherein the exposed oxide comprises silicon oxide.

8. The etching method of claim 1 , wherein the substrate further comprises a region of exposed silicon, and wherein the portion of the exposed silicon nitride is further selectively removed relative to the exposed silicon.

9. An etching method comprising:

flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber;

forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor;

flowing the plasma effluents into a processing region of the semiconductor processing chamber, wherein the processing region houses a substrate, wherein the substrate comprises a trench formed between two vertical columns, and wherein each of the two vertical columns comprises alternating layers of silicon nitride and an oxide material;

while flowing the fluorine-containing precursor into the processing region, providing a hydrogen-containing precursor to the processing region to produce an etchant, wherein the hydrogen-containing precursor bypasses the remote plasma region, wherein the hydrogen-containing precursor comprises one of diatomic hydrogen or hydrogen fluoride, and wherein a ratio of a flow rate of the fluorine-containing precursor to a flow rate of the hydrogen-containing precursor ranges between about 1:10 and about 2:1; and

selectively removing at least a portion of silicon nitride from each layer of silicon nitride with the etchant, wherein an oxygen-containing precursor is not delivered into the semiconductor processing chamber during the etching method.

10. The etching method of claim 9 , wherein a temperature of the substrate is maintained between about 30° C. and about 85° C. during the etching method.

11. The etching method of claim 9 , wherein a pressure within the semiconductor processing chamber is maintained between about 1 Torr and about 5 Torr.

12. The etching method of claim 9 , wherein the substrate comprise a region of exposed silicon, and wherein the portion of silicon nitride from each layer of silicon nitride is selectively removed relative to the exposed silicon.

13. The etching method of claim 9 , wherein the oxide material comprises silicon oxide.

14. A removal method comprising:

flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber;

forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor;

flowing a hydrogen-containing precursor into the remote plasma region of the semiconductor processing chamber, wherein the hydrogen-containing precursor comprises one of diatomic hydrogen or hydrogen fluoride, wherein the hydrogen-containing precursor bypasses the remote plasma region, and wherein a ratio of a flow rate of the fluorine-containing precursor to a flow rate of the hydrogen-containing precursor ranges between about 1:10 and about 2:1;

forming a plasma within the remote plasma region to generate plasma effluents of the hydrogen-containing precursor;

flowing the plasma effluents of the fluorine-containing precursor and the plasma effluents of the hydrogen-containing precursor into a processing region of the semiconductor processing chamber, wherein the processing region houses a substrate comprising a region of exposed silicon nitride and a region of exposed silicon oxide; and

selectively removing at least a portion of the exposed silicon nitride relative to the exposed silicon oxide, wherein an oxygen-containing precursor is not delivered into the semiconductor processing chamber during the removal method.

15. The removal method of claim 14 , wherein the substrate further comprises a region of exposed silicon, and wherein the portion of the exposed silicon nitride is removed relative to the removal method.