Etchants for removing titanium contaminant species from titanium substrates
Described are methods for removing titanium species, including titanium metal and titanium nitride, from titanium substrates. Hydrofluoric acid chemistries are traditionally disfavored for such tasks, as hydrofluoric acid tends to attack the underlying titanium substrate. A chemistry in accordance with one embodiment employs a mixture of hydrofluoric acid and hydrogen peroxide that vigorously attacks deposited titanium and titanium nitride without significantly attacking the machined titanium alloys normally used to form titanium components for semiconductor processing.
1 . A method for removing a titanium-bearing contamination layer from a contaminated titanium substrate, the method comprising exposing the contaminated titanium substrate to hydrofluoric-acid.
2 . The method of claim 1 , wherein the hydrofluoric-acid is in a solution with hydrogen peroxide.
3 . The method of claim 2 , wherein the solution includes less than two percent hydrofluoric acid and between six and thirty percent hydrogen peroxide.
4 . The method of claim 3 , wherein the solution includes between seventy and ninety percent water.
5 . The method of claim 1 , wherein the titanium-bearing contamination layer comprise titanium nitride.
6 . The method of claim 1 , wherein the titanium substrate comprises a titanium allow.
7 . The method of claim 1 , wherein the titanium substrate is a semiconductor-process component contaminated via a semiconductor process.
8 . A method for removing a titanium-bearing contamination layer from a substrate, the method comprising immersing the contaminated substrate in a hydrofluoric-acid solution, the hydrofluoric-acid solution including less than five percent hydrofluoric acid and between six and twenty-nine percent hydrogen peroxide.
9 . The method of claim 8 , wherein the solution includes more than sixty-five percent water.
10 . The method of claim 8 , wherein the substrate is stainless steel.
11 . The method of claim 10 , wherein the hydrofluoric acid solution contains less than two percent hydrofluoric acid.
12 . The method of claim 11 , wherein the hydrofluoric acid solution includes between ten and twenty-nine percent hydrogen peroxide.
13 . A cleaning solution comprising:
a. hydrofluoric acid in a concentration of less than five percent;
b. between six and twenty-nine percent hydrogen peroxide; and
c. water.
14 . The cleaning solution of claim 13 , wherein the hydrofluoric acid concentration is less than two percent.
15 . The cleaning solution of claim 13 , in liquid form.
16 . The cleaning solution of claim 13 having immersed therein a contaminated substrate of titanium.
17 . The cleaning solution of claim 16 , wherein the substrate comprises a titanium alloy.
18 . The cleaning solution of claim 16 , wherein the contaminated substrate includes a contamination layer comprised of nitrogen.