Sidewall Electrode Cleaning for Semiconductor Chamber By-Products

The cleaning process uses periodic pulsed RF power application to create alternating plasma and non-plasma phases. During the plasma phase, ions are generated and accelerated toward the sidewall by the bias voltage. During the non-plasma phase, the plasma collapses allowing by-products to re-adhere or be removed. This periodic action enables effective cleaning without continuous plasma exposure, resolving the contradiction between maintenance time and cleaning effectiveness.

The invention changes the RF power parameter from continuous to pulsed, and adjusts the bias voltage parameter to create sufficient ion acceleration during the plasma phase. By controlling the duty cycle and power level, the process achieves effective by-product removal while limiting total plasma exposure time, thus improving both cleaning effectiveness and reducing maintenance time.

The cleaning process is segmented into distinct phases: a plasma generation phase where ions are created and accelerated toward the sidewall, followed by a plasma collapse phase where the plasma is extinguished. The substrate is present only during the plasma collapse phase when ion bombardment is minimal, while the sidewall is cleaned during the plasma phase. This temporal segmentation protects the substrate from damage while maintaining cleaning effectiveness.

By using pulsed RF power with controlled duty cycle, the process limits the duration of ion bombardment to only the plasma phase portions. The periodic collapse of plasma between pulses reduces cumulative ion exposure to the substrate, preventing damage while maintaining effective sidewall cleaning during the active plasma phases.