On-chip inner-layer lens technology for an improvement in photo-sensitive characteristics of a CCD image sensor

Abstract

An on chip inner layer lens has been developed to improve the photo sensitivity and smear of CCD image sensors. The inner-layer lens structure consists of a boron phospho silicate glass (BPSG) layer and a heat melting transparent resin. The refractive indices for the inner layer lens was higher than the BPSG layer and the planarization layer. Taking the incident angle into account, we have applied a new three dimentional simulation to the inner-layer lens to investigate the optical pass. We fabricate a 1/4 -type IT-CCD image sensor with an inner-layer lens. This fabricated results of an image sensor has been explained well by the new three dimentional optical simulation. The increase of photo-sensitivity using the inner-layer lens technology is 16% without deterioration in the CCD characteristics. Furthermore using the inner-layer lens reduces the smear value by 70%.