Catalyst-assisted chemical etching with a vapor-phase etchant
View Patent ↗A method of catalyst-assisted chemical etching with a vapor-phase etchant has been developed. In one approach, a semiconductor substrate including a patterned titanium nitride layer thereon is heated, and an oxidant and an acid are evaporated to form a vapor-phase etchant comprising an oxidant vapor and an acid vapor. The semiconductor substrate and the patterned titanium nitride layer are exposed to the vapor-phase etchant during the heating of the semiconductor substrate. The vapor-phase etchant diffuses through the patterned titanium nitride layer, and titanium nitride-covered regions of the semiconductor substrate are etched. Thus, an etched semiconductor structure is formed.
1. A method of catalyst-assisted chemical etching with a vapor-phase etchant, the method comprising:
heating a semiconductor substrate including a patterned titanium nitride layer thereon;
evaporating an oxidant and an acid to form a vapor-phase etchant comprising an oxidant vapor and an acid vapor; and
during the heating, exposing the semiconductor substrate and the patterned titanium nitride layer to the vapor-phase etchant, the vapor-phase etchant diffusing through the patterned titanium nitride layer and etching titanium nitride-covered regions of the semiconductor substrate, thereby forming an etched semiconductor structure.
2. The method of claim 1 , wherein the semiconductor substrate comprises silicon, the oxidant comprises H 2 O 2 , and the acid comprises HF.
3. The method of claim 1 , wherein the vapor-phase etchant comprises a molar ratio of the oxidant vapor to the acid vapor in a range from about 0.02 to about 10.
4. The method of claim 1 , wherein the semiconductor substrate is heated to a temperature from about 30° C. to about 95° C.
5. The method of claim 1 being carried out in a controlled environment comprising an inert atmosphere or a vacuum.
6. The method of claim 1 , wherein the semiconductor substrate and the vapor-phase etchant are at the same temperature.
7. The method of claim 1 , wherein the patterned titanium nitride layer comprises a continuous mesh pattern, and
wherein the etched semiconductor structure comprises an array of nanowires.
8. The method of claim 1 , wherein the patterned titanium nitride layer comprises a discontinuous pattern having a plurality of discrete features, and
wherein the etched semiconductor structure comprises an array of channels.
9. The method of claim 1 , wherein uncovered regions of the semiconductor substrate are substantially unetched.
10. A method of titanium nitride-assisted chemical etching with a liquid-phase etchant comprises:
providing a patterned TiN layer on a semiconductor substrate;
immersing the patterned TiN layer and the semiconductor substrate into an etchant solution comprising an acid and an oxidizing agent;
during the immersion in the etchant solution, at least a portion of the semiconductor substrate immediately below the patterned TiN layer is selectively removed, thereby forming an etched semiconductor structure.
11. The method of claim 10 , wherein, during the immersion, the etchant solution comprises an elevated temperature from about 30° C. to about 95° C.