Remote Microwave Plasma Enhanced Chemical Vapour Deposition of SiO₂ Films : Oxygen Plasma Diagnostic

Abstract
Silicon oxide is deposited by remote microwave plasma enhanced chemical vapour deposition (RMPECVD). The silica films are produced by exciting oxygen in a microwave discharge while a mixture of 5% of silane diluted in argon is introduced downstream. In the afterglow, double Langmuir probe measurements and rotational temperatures deduced from optical emission spectroscopy (OES), show that the electron energy is transferred to the gas when the pressure increases (19 - 26 Pa). Therefore the electronic temperature decreases from 22000 to 11000 K and the gas temperature increases from 400 to 500 K. Moreover the microwave power (180 - 480 W) has an influence on the deposition rate and on the quality of SiO₂ coatings (density and etch rate in an HF solution). This effect can be correlated with the increase in the electron density (0.7.10¹⁰ to 3.7.10¹⁰ cm^-3) and of the gas temperature (400 to 460 K).