Etching characteristics of SiO2 in CHF3 gas plasma
The etching characteristics of SiO2} have been investigated in the CHF3} gas plasma using the planar type reactor with the 400 kHz rf power. The etch rate of SiO2}, the SiO2} /Si and SiO2}/resist etch rate ratios, and the deterioration of photoresist films are studied with a variety of etching parameters. The etching characteristics depend strongly on the coupling mode. With the cathode coupling mode, the values of 300å/min and of larger than 100 are obtained for the etch rate of SiO2} and the SiO2}/Si etch rate ratio, respectively. Only 8 is given for the SiO2} /Si etch rate ratio with the anode one. The deterioration of photoresist films less occurs with the cathode coupling mode than with the anode one. The dependences of the etching characteristics on the rf current, gas pressure, gas flow rate, and the electrode separations are also studied some in detail with the cathode coupling mode. Possible explanations for some of the experimental results are discussed.