Comparison between Bosch and STiGer Processes for Deep Silicon Etching

The cryogenic process is well known to etch high aspect ratio features in silicon with smooth sidewalls. A time-multiplexed cryogenic process, called STiGer, was developed in 2006 and patented. Like the Bosch process, it consists in repeating cycles composed of an isotropic etching step followed by a passivation step. If the etching step is similar for both processes, the passivation step is a SiF4/O2 plasma that efficiently deposits a SiOxFy layer on the sidewalls only if the substrate is cooled at cryogenic temperature. In this paper, it is shown that the STiGer process can achieve profiles and performances equivalent to the Bosch process. However, since sidewall passivation is achieved with polymer free plasma chemistry, less frequent chamber cleaning is necessary, which contributes to increase the throughput.

Light Entrapping, Modeling & Effect of Passivation on Amorphous Silicon Based PV Cell

This research paper present efforts to enhance the performance of amorphous silicon p-i-n type solar cell using sidewall passivation. For sidewall passivation, MEMS insulation material Al2O3 was used. The main objective of this paper is to observe the effect of sidewall passivation in amorphous silicon solar cell and increase the conversion efficiency of the solar cell. Passivation of Al2O3 is found effective to subdue reverse leakage. It increases the electric potential generated in the designed solar cell. It also increases the current density generated in the solar cell by suppressing the leakage. Enhancement in J-V curve was observed after adding sidewall passivation. The short circuit current density (Jsc) increased from 14.7 mA/cm2 to 18.5 mA/cm2, open circuit voltage (Voc) improved from 0.87 V to 0.89 V, and the fill factor also slightly increased. Due to the sidewall of passivation of Al2O3, conversion efficiency of amorphous silicon solar cell increased by 29.07%. At the end, this research was a success to improve the efficiency of the amorphous silicon solar cell by adding sidewall passivation.

Research of Micro-Inertial Device High-Aspect-Ratio Etching Parameters

This is mainly due to the high chemical reactivity and spontaneous etching nature of the fluorine radicals towards silicon, and the high volatility of the silicon fluorides as reaction products. Anisotropy can only be achieved by the inclusion of sidewall passivation schemes to the process. The existing approaches to deep reactive ion etching (DRIE) of silicon are distinguished by the way sidewall passivation is achieved, the key to anisotropy and overall performance of the etch process. Cryogenic etching and the so-called Bosch process with alternating etch and passivation cycles are the two most well-known high-aspect-ratio silicon etch processes and are discussed in this paper.