Characterization of PECVD Deposited Fluorosilicate Glass (FSG) After CMP and Cleaning

A characterization of Plasma-Enhanced CVD Fluorinated Silicate Glass (FSG) is presented. This study investigates the behavior of FSG film in the Chemical Mechanical Polishing (CMP) environment and compares those characteristics to undoped TEOS (UTEOS), Thermal Oxide and Si-Rich oxide capped FSG films. The removal rate, refractive index (RI), surface roughness, contact angle, water content by FTIR and thermal desorption spectroscopy (TDS) were studied. The FSG films are polished ˜ 10% faster than the undoped PECVD oxide films. Their composition was slightly changed after CMP as can be seen by the minor increase in the RI. A layer of Si-Rich oxide (SRO) was found to have a stabilizing effect on the FSG film during CMP and post CMP cleaning operations, and thus can be used in the intermetal dielectric schemes that require low dielectric constant FSG layers.