Method for treating a damaged porous dielectric
View Patent ↗In the manufacture of electronic devices that use porous dielectric materials, the properties of the dielectric in a pristine state can be altered by various processing steps. In a method for restoring and preserving the pristine properties of a porous dielectric layer, a substrate is provided with a layer of processed porous dielectric on top, whereby the processed porous dielectric is at least partially exposed. A thin aqueous film is formed at least on the exposed parts of the processed porous dielectric. The exposed porous dielectric with the aqueous film is exposed to an ambient containing a mixture comprising at least one silylation agent and dense CO 2 , resulting in the restoration and preservation of the pristine properties of the porous dielectric.
1. A method comprising:
forming a layer of pristine porous dielectric on a substrate, wherein the layer of pristine porous dielectric has at least one pristine property;
processing the layer of pristine porous dielectric to produce a layer of processed porous dielectric, thereby altering at least one of the at least one pristine properties;
forming a thin aqueous film at least on an exposed portion of the layer of processed porous dielectric; and
contacting the exposed portion of the layer of processed porous dielectric on which the aqueous film is formed with an ambient containing a mixture comprising at least one silylation agent and dense CO 2 , thereby restoring and preserving the at least one altered pristine property.
2. The method of claim 1 wherein said ambient comprises liquid CO 2 .
3. The method of claim 2 wherein said ambient is at room temperature.
4. The method of claim 1 wherein said ambient comprises supercritical CO 2 at a temperature higher than 31.1° C. and a pressure higher than 73.8 atm.
5. The method of claim 1 wherein said thin aqueous film is formed by bringing said processed porous dielectric into an atmosphere with predetermined humidity.
6. The method of claim 5 wherein the humidity of said atmosphere is between 40% and 50%.
7. The method of claim 5 wherein said atmosphere with predetermined humidity is a cleanroom environment.
8. The method of claim 1 wherein the thickness of the thin aqueous film is about 1nm.
9. The method of claim 1 wherein processing the layer of pristine porous dielectric comprises performing a chemical mechanical polishing (CMP).
10. The method of claim 9 wherein said CMP is performed without a metal hard mask overlying the porous dielectric.
11. The method of claim 9 wherein said CMP is performed with a metal hard mask overlying the porous dielectric.
12. The method of claim 1 wherein processing the layer of pristine porous dielectric comprises plasma processing.
13. The method of claim 1 wherein said porous dielectric is one of a chemical vapor deposition (CVD), a spin-on low-κ material, and an ultra low-κ material.
14. The method of claim 1 wherein said silylation agent is one of a chloroalkyl-silane (SiCl x (Alkyl) 4-x ), a chloroalkyn-silane (SiCl x (Alkyn) 4-x ), with x being an integer between 1 and 3, and any of their mixtures.
15. The method of claim 14 wherein x=3.
16. The method of claim 1 further comprising performing a thermal anneal prior to forming said aqueous film on said processed porous dielectric.
17. The method of claim 16 where the thermal anneal is performed at a temperature below 300° C.
18. The method of claim 1 further comprising an in-situ rinsing step with a mixture comprising dense CO 2 and an alcohol, after contacting the porous dielectric with the silylation agent.
19. The method of claim 1 further comprising an ex-situ rinsing step with isopropyl alcohol and deionized water, after contacting the porous dielectric with the silylation agent.