Patent ID: 6617174
Filing Date: 2003-09-09
Classification: H01L

Abstract:
A method of forming a fieldless CMOS image sensor fabricated on a substrate, the method comprising:implanting a first dopant into the substrate, wherein the first dopant includes an anti-punchthrough material; forming an oxide layer over the substrate; forming a mask on the oxide layer such that the mask covers a peripheral portion of the oxide layer and defines a central opening through which a central portion of the oxide layer is exposed; removing the central portion of the oxide layer to expose a portion of the substrate located in the central opening, wherein the mask prevents removal of the peripheral portion of the oxide layer, thereby forming an oxide barrier around the exposed substrate portion; and implanting a second dopant into the exposed substrate portion to form an image-sensing region that is surrounded by a fieldless isolation structure including an implant region formed by the implanted first dopant, and the oxide barrier that is located over the implant region.