A comparative study of copper drift diffusion in plasma deposited a-SiC:H and silicon nitride

Advanced back-end processing requires the integration of low-k dielectrics and Cu. To successfully integrate these materials, plasma deposited films for hard mask use with good resistance to wet chemicals, aggressive etch and chemical mechanical polishing are essential. As a solution to providing quality hard masks, a process has been developed for deposition of a trimethylsilane-based a-SiC:H. Depending on the deposition temperature, the dielectric constant can be varied between 4.2 and 4.9. The Cu drift rate in two different types of a-SiC:H and Si3N4 is quantified using bias temperature stressing in combination with high frequency capacitance/voltage (C/V) measurements on capacitor structures. The drift diffusion experiments indicate that a-SiC:H is a potential candidate to replace the high dielectric constant Si3N4 as a Cu diffusion barrier and hard mask. C/V measurements and elastic recoil detection are performed to show the thermal stability of the a-SiC:H up to 500 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.