Novel invention for reducing dark current of CMOS image sensor with new structure

A method of forming an image sensor comprising:

• providing a partially processed semiconductor wafer containing a p-type region;
• forming an n-type connection region within said p-type region;
• forming an n-type photodiode region within said p-type region connected to said connection region;
• forming a field oxide isolation region having a part that is over portions of said n-type connection region and over all of said n-type photodiode region, covering the area where these regions are connected and extending into these regions, ending within the n-type connecting region while leaving a distance between the edge of said part of field oxide isolation region and pn junction formed by the connection region and the p-type region and extending beyond the n-type photodiode region so that there is a distance between the edge of said part of field oxide isolation region and pn junction formed by the n-type photodiode region and the p-type region;
• forming a gate oxide over regions not covered by field oxide;
• forming an extended gate structure extending from above said part of field oxide isolation region to a distance beyond said connection region to accommodate a channel of an n-channel MOSFET and forming the drain region of the n-channel MOSFET, and with the connection region acting as the source;
• Depositing a blanket transparent insulating layer.

A structure for an image sensor comprising:

• a partially processed semiconductor wafer containing a p-type region;
• an n-type connection region within said p-type region;
• an n-type photodiode region within said p-type region connected to said connection region;
• a field oxide isolation region having a part that is over portions of said n-type connection region and n-type photodiode region covering the area where these regions are connected and extending into these regions, ending within these regions while leaving a distance between the edges of said part of field oxide isolation region and pn junctions formed by the connection region and the p-type region and the n-type photodiode region and p-type region;
• a gate oxide over regions not covered by field oxide;
• an extended gate structure extending from above said part of field oxide isolation region to a distance beyond said connection region to accommodate a channel of an n-channel MOSFET and forming the drain region of the n-channel MOSFET, and with the connection region acting as the source;
• a blanket transparent insulating layer.

A structure for forming an image sensor comprising:

• a partially processed semiconductor wafer containing a p-type region;
• an n-type connection region within said p-type region;
• an n-type photodiode region within said p-type region connected to said connection region;
• a field oxide isolation region having a part that is over portions of said n-type connection region and over all of said n-type photodiode region, covering the area where these regions are connected and extending into these regions, ending within the n-type connecting region while leaving a distance between the edge of said part of field oxide isolation region and pn junction formed by the connection region and the p-type region and extending beyond the n-type photodiode region so that there is a distance between the edge of said part of field oxide isolation region and pn junction formed by the n-type photodiode region and the p-type region;
• a gate oxide over regions not covered by field oxide;
• an extended gate structure extending from above said part of field oxide isolation region to a distance beyond said connection region to accommodate a channel of an n-channel MOSFET and forming the drain region of the n-channel MOSFET, and with the connection region acting as the source;
• a blanket transparent insulating layer.