ALD of metal silicate films
View Patent ↗Methods for forming metal silicate films are provided. The methods comprise contacting a substrate with alternating and sequential vapor phase pulses of a silicon source chemical, metal source chemical, and an oxidizing agent, wherein the metal source chemical is the next reactant provided after the silicon source chemical. Methods according to some embodiments can be used to form silicon-rich hafnium silicate and zirconium silicate films with substantially uniform film coverages on substrate surface.
1. An atomic layer deposition (ALD) method for forming a metal silicate film, the method comprising a plurality of cycles, each cycle comprising contacting a substrate in a reaction space with spatially and temporally separated vapor phase pulses of a silicon halide source chemical, a metal source chemical, and an oxidizing agent, wherein the metal source chemical is the next reactant provided after the silicon halide source chemical, wherein the metal silicate film has a silicon content greater than about 65 atomic %.
2. The method of claim 1 , further comprising purging the reaction space between each of said vapor phase pulses.
3. The method of claim 1 , wherein the silicon halide source chemical is SiCl 4 .
4. The method of claim 1 , wherein the metal source chemical is a metal halide source chemical.
5. The method of claim 4 , wherein the metal source chemical comprises Hf or Zr.
6. The method of claim 4 , wherein the metal source chemical is HfCl 4 .
7. The method of claim 1 , wherein the oxidizing agent comprises an agent selected from the group consisting of isopropyl alcohol, methanol, ethanol, a small molecular weight alcohol, NO, N 2 O, N 2 O 5 , oxygen-containing radicals, H 2 O, H 2 O 2 , O 2 , O 3 , D 2 O, and D 2 O 2 .
8. The method of claim 1 , wherein the metal silicate film is formed at a substrate temperature of about 150° C. to about 500° C.
9. The method of claim 8 , wherein the metal silicate film is formed at a substrate temperature of about 200° C. to about 450° C.
10. The method of claim 1 , wherein the metal silicate film is used in a dynamic random access memory (DRAM) device.
11. The method of claim 1 , wherein the metal silicate film is used as a gate dielectric in a complementary metal oxide semiconductor (CMOS) device.
12. An atomic layer deposition (ALD) method for forming a hafnium silicate film on a substrate in a reaction space, comprising the sequential steps of:
(a) contacting the substrate with a vapor phase pulse of an oxidizing agent;
(b) removing excess oxidizing agent and reaction by-products, if any, from the reaction space;
(c) contacting the substrate with a vapor phase pulse of a silicon halide;
(d) removing excess silicon halide and reaction by-products, if any, from the reaction space;
(e) contacting the substrate with a vapor phase pulse of a metal halide;
(f) removing excess metal halide and reaction by-products, if any, from the reaction space; and
(g) repeating steps (a) through (f) until a metal silicate film of a desired thickness is formed on the substrate, wherein no reactant is provided between steps (c) and (e), and wherein the metal silicate film has a silicon content greater than about 65 atomic %.
13. The method of claim 12 , further comprising providing an initial surface termination on the substrate prior to contacting the substrate with the vapor phase pulse of the metal source chemical.
14. The method of claim 12 additionally comprising a secondary cycle after step (f) and prior to step (g), the secondary cycle comprising providing alternately and sequentially a vapor phase pulse of silicon halide and a vapor phase pulse of an oxidizing agent.
15. The method of claim 14 , wherein the secondary cycle is repeated five times prior to step (g).