Large-area capacitively coupled discharges are widely used in plasma enhanced chemical vapor deposition (PECVD) processes for solar cell and display manufacturing. With the increase of the chamber size and driving frequency for improving production efficiency, the non-uniformity of deposited film induced by standing wave effects becomes more serious, which deserves more attention and in-depth research. Based on a fluid model coupled with a transmission line model, the potential amplitude distribution on the powered 2 m² electrode and the plasma characteristics in a capacitive plasma sustained in a silane/hydrogen discharge driven at 27.12 MHz are investigated. This work identifies three key control parameters: pressure, silane content, and input power, with particular emphasis on radial wave attenuation caused by electron-neutral elastic collisions. The simulation results are validated by industrial experimental results, confirming the relationship between the distributions of potential amplitude on the powered electrode and the film thickness.

Two different mechanisms emerge from the analysis. Under the conditions of low silane content and high power, the surface wave radial attenuation is not significant and the surface wave wavelength variations dominate the potential amplitude distribution on the powered electrode. Conversely, in the case of high silane content and low power, significant radial attenuation of the surface wave leads to the noticeable weakening of the standing wave effect due to higher electron-neutral collision frequency. Neglecting the radial attenuation of the surface wave will result in significant deviations in the potential amplitude distribution on the powered electrode as shown in the following figure.

Strategies such as adjusting power input positions or using multiple power input are studied to improve uniformity, but the improvements are still limited. Although it requires strict parameter control and machining precision, the shaped electrode demonstrates remarkable uniformity improvement of the potential distribution. In the future work, it is necessary to further analyze the influence of the standing wave effects on the radial distributions of electron, ions, and neutral radicals under complex conditions, such as different chamber structures, gas flows, and temperature distributions, as well as the influence on the quality of deposited films. This will enable a more comprehensive and accurate study of standing wave effects, providing support and guidance for solving real industrial problems.