Silicon dioxide thin films by ALD
Methods are provided for depositing silicon dioxide containing thin films on a substrate by atomic layer deposition ALD. By using disilane compounds as the silicon source, good deposition rates and uniformity are obtained.
1. An atomic layer deposition (ALD) process for producing a thin film comprising silicon dioxide on a substrate comprising a deposition cycle comprising:
contacting a substrate with a vaporized silicon compound such that the silicon compound adsorbs to the substrate; and
converting the adsorbed silicon compound into silicon dioxide by contacting it with a reactive vaporized oxygen source compound; wherein the silicon compound has a Si—Si bond and formula of:
R III 3-x (R II R I N) x —Si—Si—(N—R I R II ) y R III 3-y ,
wherein the x is selected from 1 to 3;
y is selected from 1 to 3;
R I is selected from the group consisting of hydrogen, alkyl and substituted alkyl;
R II is selected from the group consisting of alkyl and substituted alkyl; and
R III is selected from the group consisting of hydrogen, hydroxide (—OH), amino (—NH2), alkoxy, alkyl and substituted alkyl;
and wherein each x, y, R III , R II and R I can be selected independently from each other.
2. The process of claim 1 , wherein the silicon compound is hexakis(monoalkylamino)disilane (R II —NH) 3 —Si—Si—(NH—R II ) 3 .
3. The process of claim 1 , wherein the silicon compound is hexakis(ethylamino)disilane (Et-NH) 3 —Si—Si—(NH-Et) 3 .
4. The process of claim 1 , wherein the deposition cycle is repeated until a silicon dioxide thin film of the desired thickness is formed.
5. The process of claim 1 , wherein the temperature of the silicon compound is held above 60° C. during deposition.
6. The process of claim 5 , wherein the deposition temperature is from about 150° C. to 350° C.
7. The process of claim 5 , wherein the deposition temperature is from about 250° C. to 300° C.
8. The process of claim 1 , wherein growth rate of the film is above 0.8 Å/cycle.
9. The process of claim 1 , wherein growth rate of the film is above 1.0 Å/cycle.
10. The process of claim 1 , wherein contacting a substrate with a vaporized silicon compound comprises supplying the silicon compound in a pulse of about 0.1 to about 5 seconds.
11. The process of claim 1 , wherein contacting a substrate with a vaporized oxygen source compound comprises supplying an oxygen source compound in a pulse of about 0.1 to about 5 seconds.
12. The process of claim 1 , wherein the process is performed in a flow-type reactor.
13. The process of claim 1 , wherein the process is performed in a batch ALD reactor capable of processing more than one substrate.
14. The process of claim 13 , wherein the process conditions are selected such that the thickness variation from substrate to substrate processed in the batch ALD reactor is less than about 0.5%.
15. The process of claim 13 , wherein the thickness variation within each wafer processed in the batch ALD reactor is less than about 0.5%.
16. The process of claim 13 , wherein the batch ALD reactor is capable of processing more than 100 wafers in one batch.
17. The process of claim 1 , wherein the oxygen source compound comprises ozone.
18. The process of claim 17 , wherein the ozone comprises a mixture of ozone/oxygen, ozone having concentration from about 5 vol-% to about 40 vol-%.
19. The process of claim 1 , wherein the oxygen source compound comprises atomic oxygen.
20. The process of claim 1 , wherein the oxygen source compound is selected from the group consisting of oxygen plasma and oxygen radicals.
21. The process of claim 1 , wherein the deposited film has less than 2 at-% of nitrogen as an impurity.
22. The process of claim 1 , wherein the deposited film has less than 1 at-% of carbon as an impurity.
23. The process of claim 1 , wherein the process is used for filling trenches.
24. The process of claim 1 , wherein the step coverage of the process is more than 90%.
25. The process of claim 1 , wherein the process is used for depositing spacers.
26. A method for forming a silicon dioxide thin film on a substrate in a reaction chamber by atomic layer deposition, the method comprising a deposition cycle comprising:
providing a vapor phase pulse of a first reactant comprising a first silicon source precursor to the reaction chamber such that it forms no more than a monolayer on the substrate;
removing excess first reactant from the reaction chamber;
providing a vapor phase pulse of a second reactant comprising an oxygen source to the reaction chamber; and
removing excess second reactant and any reaction byproducts from the reaction chamber;
wherein the providing and removing steps are repeated until a thin silicon dioxide film of a desired thickness is obtained, and wherein the silicon compound is hexakis(monoalkylamino)disilane (R II —NH) 3 —Si—Si—(NH—R II ) 3 and R II is selected from the group consisting of alkyl and substituted alkyl.
27. The method of claim 25 , wherein the deposition temperature is from about 150° C. to 350° C.
28. A method for forming a silicon dioxide thin film by atomic layer deposition on a substrate in a reaction chamber comprising:
alternately and sequentially providing a vapor phase reactant pulse comprising a silicon precursor and a vapor phase reactant pulse comprising an oxygen precursor to the reaction chamber;
wherein the vapor phase reactant pulses are repeated until a thin film of a desired thickness is obtained; wherein the silicon compound is hexakis(ethylamino)disilane (Et-NH) 3 —Si—Si—(NH-Et) 3 .
29. The method of claim 27 , wherein the deposition temperature is from about 250° C. to 300° C.