Ultralow dielectric constant layer with controlled biaxial stress

Abstract

A method for forming a ultralow dielectric constant layer with controlled biaxial stress is described incorporating the steps of forming a layer containing Si, C, O and H by one of PECVD and spin-on coating and curing the film in an environment containing very low concentrations of oxygen and water each less than 10 ppm. A material is also described by using the method with a dielectric constant of not more than 2.8. The invention overcomes the problem of forming films with low biaxial stress less than 46 MPa.

1 . A curing process wherein an ultralow dielectric constant film containing elements of Si, C, O and H is cured, said curing is performed using an energy source selected from the group of thermal, electron beam, plasma, UV, DUV and laser in an environment containing controlled and very low concentrations of oxygen and water, each in the range from 0 to 100 ppm, resulting in a film with low and controllable biaxial stress. 
     
     
         2 . The process of  claim 1  wherein said film is exposed a second time to one or more energy sources selected from the group of thermal, electron beam, plasma, UV, DUV and laser, in an environment containing controlled and very low concentrations of oxygen and water, each in the range from 0 to 10 ppm. 
     
     
         3 . The process of  claim 1  wherein said curing is done by heating said film at temperatures not lower than 300° C. for a period of not less 0.25 hours. 
     
     
         4 . The process of  claim 1  wherein said curing is performed using an energy source selected from the group of electron beam, plasma, UV, DUV (deep UV) and laser, while said film is kept at temperatures not lower than 300° C. 
     
     
         5 . An integrated PECVD-Cure process for fabricating an ultralow dielectric constant film containing elements of Si, C, O and H, and exhibiting low and controllable biaxial stress, comprising:
 depositing said film on a substrate using plasma enhanced chemical vapor deposition (PECVD);   transferring said substrate between process areas in a non-oxidizing environment containing a controlled very low concentration of oxygen in the range from 0 to 100 ppm;   curing the deposited film in an environment containing controlled very low concentrations of oxygen or water each in the range from 0 to 100 ppm;   allowing said substrate to cool in a non oxidizing environment containing controlled very low concentrations of oxygen or water each in the range from 0 to 10 ppm, before it is exposed to ambient atmosphere.   
     
     
         6 . The process of  claim 5  wherein the environment is a non-oxidizing hydrocarbon ambient with double bond groups and with the oxygen level less than 10 ppm to passivate reactive sites after curing and to reduce the SiCOH and porous SiCOH film oxidation. 
     
     
         7 . The process of  claim 6  wherein said hydrocarbon ambient double bond groups include ethylene or 1,3butadiene.