Planarization film by plasma enhanced chemical vapor deposition and low temperature oxide as conformal insulator

Amorphous carbon films have been deposited by plasma enhanced chemical vapor deposition which provide a high degree of planarization over large distances. These films can be deposited at room temperature with low ion bombardment energy (10 V) and high deposition rate (300 nm/min). The planar films have low viscosity and molecular weight, and their molecular structure is similar to that of the source gases. A post-deposition hardening step was utilized to improve the compatibility of the films with subsequent processing steps by heating the samples and/or exposing them to a low power plasma. Submicrometer patterns have been defined using excimer laser projection lithography in bilayer resist. In addition, a multipolar electron cyclotron resonance source was used to generate an oxygen plasma for Si oxidation. Oxidation rate was found to increase with microwave power but decrease with source distance and if power. Maximum oxidation rate was found at 0.25 mTorr. This low pressure is desirable for forming conformal insulator. The oxide films were found to have O to Si ratio of 2 and refractive index of 1.47. Breakdown field was >12 MV/cm and fixed charge density was 3xl0¹⁰ cm-2.