Semiconductor Trench Etching Scallop Control

The opening formation process is divided into multiple cycles, each cycle creating a portion of the final opening. By segmenting the etching into repeated isotropic and anisotropic steps with protective film deposition in between, the process achieves both depth and vertical shape while managing scalloping through controlled cycles

The Bosch process uses periodic repetition of etching and protective film deposition cycles. Each cycle consists of isotropic etching followed by protective film formation, then anisotropic etching to remove the film from the bottom. This periodic action allows the opening to be deepened progressively while maintaining vertical walls and controlling scalloping

The process uses periodic repetition of standardized etching and deposition cycles to achieve great opening depths. Each cycle follows the same pattern: isotropic etching, protective film deposition, and anisotropic etching. This periodic approach systematically increases depth while maintaining process control and reducing overall complexity through repetition of proven steps

Protective film is deposited in advance on the side surfaces before the anisotropic etching step. This preliminary protective action prevents unwanted etching of the sides during the anisotropic phase, allowing the process to safely repeat cycles to achieve greater depths without compromising structural integrity