SIOFX AND SIO2 DEPOSITION IN AN ECR-HDP REACTOR - TOOL CHARACTERIZATION AND FILM ANALYSIS

We present a study on the deposition of low-k inter metal dielectric ( LMD) for high-aspect ratio trench filling. Using an HDP-CVD reactor we demonstrate uniform filling of trenches of aspect ratios up to 1.6 wi th SiO2. This gap-filling capability is achieved by simultaneously gro wing and sputtering. The sputter component is obtained by RE-biasing o f the substrate. We show that a trade-off exists between gap fill and growth rate. In order to characterize the HDP tool we define the figur e of merit (FOM) as the product of growth rate and gap-filling capabil ity, and we show that the FOM is mainly determined by the available mi crowave power. Next, we demonstrate the deposition of SiOFx as a low-k LMD. By the incorporation of fluorine in the SiO2 film the dielectric constant of the oxide can be decreased from 4.0 to about 3.5. Also it is shown that the silicon content of the film is an important paramet er determining the dielectric constant.