EVALUATION OF CF2 RADICAL AS A PRECURSOR FOR FLUOROCARBON FILM FORMATION IN HIGHLY SELECTIVE SIO2 ETCHING PROCESS USING RADICAL INJECTION TECHNIQUE

A radical injection technique (RIT) was developed to evaluate CF2 radi cal as a precursor for fluorocarbon film formation in a highly selecti ve SiO2 etching process. Using RIT, the CF2 radical was successfully i njected into electron cyclotron resonance (ECR) downstream plasmas emp loying Ar and H-2/Ar mixtures. The fluorocarbon films formed on the Si surfaces exposed to ECR downstream plasmas were investigated using X- ray photoelectron spectroscopy. The deposition rate of fluorocarbon fi lms was measured by varying microwave power in the Ar and H-2/Ar ECR p lasmas while keeping CF2 radical density constant using RIT. From the experimental results, it was found that the CF2 radical was the import ant precursor for fluorocarbon film formation only with the assistance of the surface activation due to the plasma exposure and that H atoms and CF2 radicals in the plasma played an important role in the format ion of carbon-rich fluorocarbon film resulting in highly selective SiO 2 etching. Furthermore, the highly selective SiO2 etching was demonstr ated using the H-2/Ar ECR downstream plasma with CF2 radical injection .