Method of improving solid-state image sensor sensitivity

Abstract

An imaging apparatus includes (a) a full-frame, charge-coupled device having (i) a conductive layer of a first dopant type; (ii) a plurality of pixels arranged as a charge-coupled device in the conductive layer that collects charge in response to incident light and transfers the collected charge; (iii) an overflow drain of a dopant type opposite the first type disposed in the conductive layer and laterally adjacent to each pixel; and the apparatus having (b) a voltage supply connected to the lateral overflow drain that is at a first voltage during readout and at a second voltage that is lower than the first voltage during integration.

1 . An imaging apparatus comprising:
 (a) a full-frame, charge-coupled device comprising:
 (i) a conductive layer of a first dopant type; 
 (ii) a plurality of pixels arranged as a charge-coupled device in the conductive layer that collects charge in response to incident light and transfers the collected charge; 
 (iii) an overflow drain of a dopant type opposite the first type disposed in the conductive layer and laterally adjacent to each pixel; and 
   (b) a voltage supply connected to the lateral overflow drain that is at a first voltage during readout and at a second voltage that is lower than the first voltage during integration.   
   
   
       2 . The imaging apparatus as in  claim 1 , wherein the first dopant type is p-type. 
   
   
       3 . The imaging apparatus as in  claim 1 , wherein the lower voltage is at a voltage substantially close to a voltage of the conductive layer. 
   
   
       4 . The imaging apparatus as in  claim 3 , wherein the conductive layer voltage is at ground potential. 
   
   
       5 . The imaging apparatus as in  claim 1 , wherein the dopant type of the overflow drain is n-type. 
   
   
       6 . The imaging apparatus as in  claim 1 , wherein the conductive layer is an epitaxial layer. 
   
   
       7 . The imaging apparatus as in  claim 1 , wherein the conductive layer is a substrate. 
   
   
       8 . A method for operating an imaging apparatus comprising the steps of:
 (a) providing a conductive layer of a first dopant type;   (b) providing a plurality of pixels arranged as a charge-coupled device in the conductive layer that collects charge in response to incident light and transfers the collected charge;   (c) providing an overflow drain of a dopant type opposite the first type disposed in the conductive layer and laterally adjacent to each pixel; and   (d) supplying a first voltage to the lateral overflow drain during readout and supplying a second voltage that is lower than the first voltage during integration.   
   
   
       9 . The method as in  claim 8  further comprising the step of providing p-type as the first dopant type. 
   
   
       10 . The method as in  claim 8  further comprising the step of providing a voltage substantially close to a voltage of the conductive layer as the lower voltage. 
   
   
       11 . The method as in  claim 10  further comprising the step of providing the conductive layer voltage at ground potential. 
   
   
       12 . The method as in  claim 8  further comprising the step of providing n-type as the dopant type of the overflow drain. 
   
   
       13 . A camera comprising
 (a) a full-frame, charge-coupled device comprising:
 (i) a conductive layer of a first dopant type; 
 (ii) a plurality of pixels arranged as a charge-coupled device in the conductive layer that collects charge in response to incident light and transfers the collected charge; 
 (iii) an overflow drain of a dopant type opposite the first type disposed in the conductive layer and laterally adjacent to each pixel; and 
   (b) a voltage supply connected to the lateral overflow drain that is at a first voltage during readout and at a second voltage that is lower than the first voltage during integration.   
   
   
       14 . The camera as in  claim 13 , wherein the first dopant type is p-type. 
   
   
       15 . The camera as in  claim 13 , wherein the lower voltage is at a voltage substantially close to a voltage of the conductive layer. 
   
   
       16 . The camera as in  claim 15 , wherein the conductive layer voltage is at ground potential. 
   
   
       17 . The camera as in  claim 13 , wherein the dopant type of the overflow drain is n-type. 
   
   
       18 . The camera as in  claim 13 , wherein the conductive layer is an epitaxial layer. 
   
   
       19 . The camera as in  claim 13 , wherein the conductive layer is a substrate.