A novel method for thickness profile control in RF PECVD deposition on large area substrates

This paper discusses a novel method of plasma deposition or etching for producing uniform or controlled non-uniform profiles on large substrates. A plasma enhanced chemical vapour deposition (PECVD) system with dual electrodes was assembled using this method. An analytic expression for radial and angular movement of plasma source was given. Plasma diagnosis was carried out in order to understand the effect of the position of the plasma electrodes. We found that for a given phase difference between the two electrodes, the plasma potential was independent of the distance between the electrodes and the nearest wall when the distance was greater than 80 mm. When the distance was less than 80 mm, the floating potential varied significantly for a given phase difference. The nearest distance of the electrodes to chamber walls had a similar effect to the RF self-bias. PECVD thin film deposition was carried out for both uniform and controlled non-uniform profiles. The examples presented included linearly graded and parabolic profiles along the radius of the substrates. The results show that this method is capable of producing controlled thickness profiles on large substrates. The advantages of this method include simplicity, flexibility, and scalability.