Integration Issues for Diamond Like Carbon in a Copper Damascene Process Flow

Hydrogenated “diamondlike” carbon (DLC) is a potential candidate as a low k material for the back end interconnect (BEOL) dielectric for VLSI chips. The DLC material is an attractive dielectric due to its isotropic properties and the ability to deposit the films by CVD techniques, such as PECVD or HDP systems. Under suitable preparation conditions such materials can reach dielectric constant values below 2.8, even as low as 2.4. While the as-deposited films are not stable to exposure to subsequent processing temperatures of about 400 C, it appears that they can be stabilized, in terms of dimensional stability and material loss, by an initial anneal. The integration of DLC films in the BEOL structure further requires good adhesion with the materials in contact with the DLC dielectric, such as silicon nitride or silicon oxide, and liner metallurgy. As the potential application of the DLC films will be in Cu based damascene structures the behavior of the films under CMP conditions is also important. The talk will discuss the evaluation of DLC films and of integration issues such as adhesion under processing conditions, patterning, CMP behavior. Blanket and patterned structures built with DLC films will be presented.