Abstract: The present disclosure relates to a back-side illuminated CMOS image sensor (BSI CIS). In some embodiments, the BSI CSI has a semiconductor substrate with a front-side and a back-side. A plurality of photodetectors are located within the front-side of the semiconductor substrate. An implantation region is located within the semiconductor substrate at a position separated from the plurality of photodetectors. The implantation region is disposed below the plurality of photodetectors and has a non-uniform doping concentration along a lateral plane parallel to the back-side of the semiconductor substrate. The non-uniform doping concentration allows for the BSI CSI to achieve a small total thickness variation (TTV) between one or more photodetectors and a back-side of a thinned semiconductor substrate that provides for good device performance.

Abstract: The present disclosure relates to a back-side illuminated CMOS image sensor (BSI CIS). In some embodiments, the BSI CSI has a semiconductor substrate with a front-side and a back-side. A plurality of photodetectors are located within the front-side of the semiconductor substrate. An implantation region is located within the semiconductor substrate at a position separated from the plurality of photodetectors. The implantation region is disposed below the plurality of photodetectors and has a non-uniform doping concentration along a lateral plane parallel to the back-side of the semiconductor substrate. The non-uniform doping concentration allows for the BSI CSI to achieve a small total thickness variation (TTV) between one or more photodetectors and a back-side of a thinned semiconductor substrate that provides for good device performance.

Abstract: The present disclosure relates to a method of forming a back-side illuminated CMOS image sensor (BSI CIS). In some embodiments, the method comprises forming a plurality of photodetectors within a front-side of a semiconductor substrate. An implant is performed on the back-side of the semiconductor substrate to form an implantation region having a doping concentration that is greater in the center than at the edges of the semiconductor substrate. The back-side of the workpiece is then exposed to an etchant, having an etch rate that is inversely proportional to the doping concentration, which thins the semiconductor substrate to a thickness that allows for light to pass through the back-side of the substrate to the plurality of photodetectors. By implanting the substrate prior to etching, the etching rate is made uniform over the back-side of the substrate improving total thickness variation between the photodetectors and the back-side of the substrate.

Abstract: The present disclosure relates to a method of forming a back-side illuminated CMOS image sensor (BSI CIS). In some embodiments, the method comprises forming a plurality of photodetectors within a front-side of a semiconductor substrate. An implant is performed on the back-side of the semiconductor substrate to form an implantation region having a doping concentration that is greater in the center than at the edges of the semiconductor substrate. The back-side of the workpiece is then exposed to an etchant, having an etch rate that is inversely proportional to the doping concentration, which thins the semiconductor substrate to a thickness that allows for light to pass through the back-side of the substrate to the plurality of photodetectors. By implanting the substrate prior to etching, the etching rate is made uniform over the back- side of the substrate improving total thickness variation between the photodetectors and the back-side of the substrate.