Carbon containing low-k dielectric constant recovery using UV treatment
A method for the ultraviolet (UV) treatment of carbon-containing low-k dielectric and associated apparatus enables process induced damage repair. The methods of the invention are particularly applicable in the context of damascene processing to recover lost low-k property of a dielectric damaged during processing, either pre-metallization, post-planarization, or both. UV treatments can include an exposure of the subject low-k dielectric to a constrained UV spectral profile and/or chemical silylating agent, or both.
1. A method of forming a semiconductor device, comprising:
receiving in a processing chamber a semiconductor device substrate comprising a carbon-containing low-k dielectric having a first dielectric constant;
exposing the carbon containing low-k dielectric to a UV treatment, the treatment comprising at least one of:
(a) exposure to UV radiation having a spectral profile characterized by greater than 50% of the UV radiation power having a wavelength of greater than 300 nm; and
(b) exposure to UV radiation and a chemical silylating agent;
such that the dielectric constant of the carbon-containing low-k dielectric is decreased to a second dielectric constant;
wherein the treatment comprises exposure to the chemical silylating agent prior to the UV radiation exposure; and
wherein a second UV radiation exposure precedes the exposing the carbon containing low-k dielectric to the chemical silylating agent.
2. The method of claim 1 , wherein there is no air-break between exposures.
3. The method of claim 1 , wherein there is an air-break between one or more exposures.
4. The method of claim 1 , wherein a thermal anneal exposure precedes the exposing the carbon containing low-k dielectric to the chemical silylating agent.
5. The method of claim 1 , wherein the dielectric is selected from the group consisting of carbon doped oxides formed from octamethyl cyclotetrasiloxane (OMCTS), tetramethylcyclotetrasiloxane (TMCTS), dimethyldimethoxysilane (DMDMOS), and diethoxymethylsilane (DEMS).
6. The method of claim 5 , wherein the alkyl silane is selected from the group consisting of dimethyldichlorosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, bis(dimethylamino)dimethylsilane, dimethylaminao trimethyl silane, bis(diethylamino)dimethylsilane, ethylmethyldichlorosilane and diethyldichlorosilane, diethyldiethoxysilane.
7. The method of claim 6 , wherein the silylating agent is bis(dimethylamino)dimethylsilane.
8. The method of claim 6 , wherein the silylating agent is dimethyldichlorosilane.
9. The method of claim 1 , wherein greater than 50% of the (a) and/or (b) UV radiation power is in a wavelength range of about 300 to 450 nm.
10. The method of claim 1 , wherein greater than 50% of the (a) and/or (b) UV radiation power is in a wavelength range of about 300 to 400 nm.
11. The method of claim 1 , wherein less than 10% of the (a) and/or (b) UV radiation power is in a wavelength range below 300 nm.
12. The method of claim 1 , wherein less than 5% of the (a) and/or (b) UV radiation power is in a wavelength range below 300 nm.
13. The method of claim 1 , wherein less than 1% of the (a) and/or (b) UV radiation power is in a wavelength range below 300 nm.
14. The method of claim 1 , wherein the proportion of (a) and/or (b) UV radiation power in a wavelength range of 200 to 240 nm to UV radiation power in a wavelength range of 300 to 400 nm in the UV radiation to which the carbon containing low-k dielectric is exposed is no more than 10%.
15. The method of claim 1 , wherein a Fe-filled (“D”) bulb is used a source for the (a) and/or (b) UV radiation.
16. The method of claim 15 , wherein a high pass filter is used with the D bulb to filter out the UV radiation having a wavelength below 300 nm prior to exposure of the carbon containing low-k dielectric.
17. The method of claim 16 , wherein the filter is a 295 nm high pass filter.
18. The method of claim 1 , wherein a Ga-filled (“V”) bulb is used a source for the (a) and/or (b) UV radiation.
19. The method of claim 18 , wherein a high pass filter is used with the V bulb to filter out the UV radiation having a wavelength below 300 nm prior to exposure of the carbon containing low-k dielectric.
20. The method of claim 19 , wherein the filter is a 295 nm high pass filter.