Chemical treatment of semiconductor substrates
View Patent ↗A method is disclosed for removing liquids from a semiconductor substrate by contacting the liquid on the substrate with a liquid which attracts the liquid on the substrate, separating the liquids from the substrate, and inducing a phase transition in a layer on the substrate. In particular, the method is applicable to removing water from a water-containing layer on the substrate by contacting the layer with a hygroscopic liquid. Trenches on a substrate can be isolated by filling the trenches with a water-containing gel formed by reacting silane and hydrogen peroxide. The gel is contacted with sulfuric acid to remove a portion of the water from the gel before annealing to form silica in the trenches. Unlike filled trenches formed by conventional technology, there are no voids in the bottom of the trenches. The method is also applicable to forming dielectric layers which cover metal lines, low-dielectric layers, and interlayer dielectric layers. The liquid may be applied to the substrate by chemical vapor deposition or by spin-applying.
1. A method of treating a semiconductor substrate in a chamber, the method comprising:
forming a first liquid layer containing a second liquid on the semiconductor substrate;
contacting the first liquid layer with an organic solvent that attracts the second liquid and transferring at least a portion of the second liquid from the first liquid layer into the organic solvent;
separating the organic solvent from the first liquid layer; and
inducing a phase transition in the first liquid layer.
2. The method of claim 1 , wherein the organic solvent comprises ethanol.
3. The method of claim 1 , wherein the second liquid comprises an organic liquid.
4. The method of claim 3 , wherein the second liquid is selected from the group consisting of hydrocarbons, chlorinated solvents, alcohols, ethers, aldehydes, ketones, and silicones.
5. The method of claim 1 , wherein the second liquid comprises water.
6. The method of claim 5 , wherein the first liquid layer is contacted with the second-liquid-attractive organic solvent at a temperature of between about 1° C. and about 150° C.
7. The method of claim 1 , wherein the substrate comprises a plurality of trenches and wherein the method is part of a process for filling the trenches with insulator.
8. A method of treating a semiconductor substrate in a chamber, the method comprising:
forming a liquid layer containing water on the semiconductor substrate;
contacting the liquid layer with a hygroscopic acid solution and transferring at least a portion of the water from the liquid layer into the hygroscopic acid solution;
separating the hygroscopic acid solution from the liquid layer;
removing at least a portion of the remaining water from the liquid layer; and
annealing the substrate and the liquid layer.
9. The method of claim 8 , wherein the hygroscopic acid solution comprises phosphoric acid.
10. The method of claim 9 , wherein the concentration of the phosphoric acid ranges from about 70 to about 100 weight percent with reference to the total weight of the solution.
11. The method of claim 10 , wherein the concentration of the phosphoric acid ranges from about 75 to about 85 weight percent with reference to the total weight of the solution.
12. The method of claim 8 , wherein the liquid layer is contacted with the hygroscopic acid solution for a period of about 1 minute to about 120 minutes.
13. The method of claim 12 , wherein the liquid layer is contacted with the hygroscopic acid solution for a period of about 20 minutes to about 60 minutes.
14. The method of claim 8 , wherein forming the liquid layer comprises spraying a liquid on the semiconductor substrate.
15. The method of claim 8 , wherein forming the liquid layer comprises using a spin-on process.
16. The method of claim 8 , wherein the substrate comprises an insulator.
17. The method of claim 16 , wherein the insulator comprises sapphire.
18. The method of claim 8 , wherein removing at least a portion of the remaining water comprises exposing the substrate and the liquid layer to reduced pressure.
19. The method of claim 8 , wherein removing at least a portion of the remaining water comprises exposing the substrate and the liquid layer to plasma.
20. The method of claim 8 , wherein separating the hygroscopic acid solution comprises dipping the substrate and the liquid layer into a solvent in which the hygroscopic acid is soluble.
21. The method of claim 20 , wherein the solvent comprises deionized water.
22. The method of claim 8 , wherein the substrate and the liquid layer are annealed for between about 1 minute and about 60 minutes.
23. The method of claim 22 , wherein the substrate and the liquid layer are annealed for between about 10 minutes and about 30 minutes.
24. A method of filling shallow trenches on a semiconductor substrate, comprising:
providing a plurality of shallow trenches on a semiconductor substrate;
forming a gel containing oligomers and water in the shallow trenches, the gel filling at least a portion of the shallow trenches;
contacting the gel with a hygroscopic solvent and transferring at least a portion of the water from the gel into the solvent;
separating the solvent from the gel; and
annealing the substrate and the gel.
25. The method of claim 24 , further comprising removing at least a portion of remaining water from the gel after separating and prior to annealing.
26. The method of claim 24 , wherein forming the gel comprises forming a planarized surface.