Etch Process Development for a New CMOS Image Sensor

摘要

A novel CIS, called the backside-illuminated (BSI) CIS, is more light-sensitive and less noisy than the traditional front-illuminated (FI) CIS. The key parameters in BSI etch are sidewall profile angle, micro-trenching, and silicon loss macro-loading. In this paper, theh Applied Centura® AdvantEdge™ Mesa™ etch chamber was used to develop a BSI CIS etch process. The target profile for sidewall angle can be achieved by tuning C4F8 flow. Tuning the pressure minimizes micro-trenching at the bottom of the BSI pad. For macro-loading of silicon loss, DC (Div. Cap) and MRAD (Motorized Radial Assembly Dial) tuning can achieve minimal silicon loss with good uniformity.