Top Bowing Optimization of High Aspect-Ratio DTC with Low-Temperature Plasma Etching

Deep-trench capacitors (DTCs) with high aspect ratios are critical for advanced memory and three-dimensional integration technologies, particularly for continued device scaling and integration density improvement. However, precise profile control in high-aspect-ratio DTC fabrication remains challenging due to severe top bowing caused by ion scattering and excessive lateral chemical etching. In this work, a low-temperature plasma etching process was investigated to improve the profile control of DTCs, focused on top bowing optimization. The results show that reducing the etching temperature effectively suppresses lateral chemical etching and improves sidewall passivation, leading to a significant mitigation of top bowing over a wide process window. With the optimized low-temperature conditions, DTC structures with nearly vertical sidewalls and aspect ratios up to ~62 were achieved, indicating that low-temperature plasma etching provides a practical solution for profile control in high-aspect-ratio DTC fabrication.