ICP Etching of SiC and GaN for Deep Vertical Features

The patent applies parameter changes by optimizing plasma power, gas flow rates, pressure, and temperature to achieve both deep etching and high aspect ratios in SiC and GaN materials. The ICP etch process uses specific parameter combinations (e.g., high plasma power for etch rate, controlled gas flows for anisotropy) to resolve the contradiction between etch depth and productivity.

The patent employs periodic action through pulsed etching cycles with alternating etch and passivation steps. This allows the formation of deep features with high aspect ratios by periodically removing material and then protecting sidewalls, enabling continued deep etching without sacrificing sidewall integrity or overall productivity.

The patent applies preliminary action by performing a sidewall passivation step before the main etching process. A protective layer is deposited on the sidewalls in advance, which prevents lateral etching and ensures vertical sidewall formation during the subsequent anisotropic etching step, thereby maintaining both shape and manufacturing precision.

The patent segments the etching process into multiple distinct steps: sidewall passivation, anisotropic etching, and cleanup. This segmentation allows each step to be optimized independently - the passivation step ensures vertical sidewalls while the etching step controls dimensional precision, resolving the contradiction between shape and manufacturing precision.

The patent overcomes the strong Si-C bond strength by applying parameter changes including high plasma power, optimized gas composition (e.g., CF4, SF6 with O2 or H2), and controlled temperature. These parameters enhance the plasma reactivity and ion energy to break Si-C bonds more effectively, achieving high etch rates in SiC materials.

The patent uses composite plasma chemistry combining fluorocarbon gases (for Si-C bond breaking) with oxygen or hydrogen (for byproduct removal and sidewall protection). This composite approach enables simultaneous achievement of high etch rates and good feature quality by leveraging the complementary actions of different gas components.

The patent uses periodic etch-passivation cycles to maintain feature quality during deep etching. The periodic passivation step prevents defect formation by protecting sidewalls from damage, while the etch step progresses the feature depth. This periodic action ensures both high reliability and low defect density in the final etched features.

The patent performs preliminary sidewall passivation before main etching to prevent defect formation during the etching process. This preliminary protective layer prevents particulate generation, sidewall damage, and other defects, ensuring high feature quality and reliability while maintaining manufacturing precision.