Method to deposit an impermeable film on porous low-k dielectric film
A method for improving the adhesion of an impermeable film on a porous low-k dielectric film in an interconnect structure is disclosed. The method provides an in-situ annealing step before the deposition of the impermeable film to release the volatile trapped molecules such as water, alcohol, HCl, and HF vapor, inside the pores of the porous low-k dielectric film. The method also provides an in-situ deposition step of the impermeable film right after the deposition of the porous low dielectric film without exposure to an atmosphere containing trappable molecules. The method further provides an in-situ deposition step of the impermeable film right after the removal a portion of the porous low-k dielectric film without exposure to an atmosphere containing trappable molecules. By the removal of all trapped molecules inside the porous low-k dielectric film, the adhesion between the deposited impermeable film and the low-k dielectric film is improved. This method is applicable to many porous low-k dielectric films such as porous hydrosilsesquioxane or porous methyl silsesquioxane, porous silica structures such as aerogel, low temperature deposited silicon carbon films, low temperature deposited Si—O—C films and methyl doped porous silica.
1. A method to improve the adhesion of an impermeable film on a porous low-k dielectric film, the method comprising:
annealing the porous low dielectric film by heating the porous low dielectric film for a sufficient length of time to remove volatile molecules that are trapped inside the porous low-k dielectric film; and
depositing an impermeable film on the porous low-k dielectric film without exposing the porous low-k dielectric fun to an atmosphere containing trappable molecules.
wherein the anneal process removes essentially all volatile molecules including organic material and moisture from the porous low-k dielectric film.
2. A method as in claim 1 wherein the porous material is selected from the group consisting of porous MSQ, porous HSQ, porous silica structures, low temperature deposited silicon carbon films, low temperature deposited Si—O—C films, and methyl doped porous silica.
3. A method as in claim 1 wherein the impermeable film is selected from the group consisting of TiN, TaN, WN, TiSiN, TaSiN, WSiN, SiO 2 , Si 3 N 4 , metal films and Si films.
4. A method as in claim 1 wherein the deposition method to deposit the impermeable film is selected from the group consisting of a CVD, ALD, nanolayer deposition NLD, and sputtering techniques.
5. A method as in claim 1 wherein the porous low-k dielectric film has a protective layer on top.
6. A method as in claim 1 wherein the temperature of the anneal process is between 50° C. and 500° C.
7. A method as in claim 1 wherein the anneal time is between 10 seconds and 2 hours.
8. A method as in claim 1 wherein the anneal process is performed by resistive heater or radiative heater.
9. A method as in claims 1 wherein anneal ambient is selected from the group consisting of nitrogen, and inert gases.
10. A method as in claim 1 wherein the pressure of the anneal process is below atmospheric pressure.
11. A method as in claim 1 wherein the anneal step and the deposition step are performed in two separate chambers and the method further comprises an intermediate step of transferring the porous low-k dielectric film from an anneal chamber to a deposition chamber also without exposing the porous low-k dielectric film to an atmosphere containing trappable molecules.
12. A method as in claim 11 wherein the atmosphere not containing trappable molecules is a sub atmospheric pressure ambient.
13. A method as in claim 11 wherein the anneal chamber process is a batch process and the deposition process is a single process.
14. A method as in claim 1 wherein the porous low-k dielectric film has a protective layer on top.
15. The method as in claim 1 wherein the porous low dielectric film is in an integrated circuit.