MOS-based active pixel sensor cell that utilizes the parasitic bipolar action of the cell to output image data

A method for collecting light energy in an active pixel sensor cell formed on a semiconductor bulk, the cell comprising:

• a first layer of insulation formed on the semiconductor bulk;
• a body of a first conductivity type formed on the first layer of insulation;
• spaced-apart source and drain regions of a second conductivity type formed in the body, the source and drain regions contacting the first layer of insulation;
• a channel region of the body defined to extend downward from a top surface of the body and from the source region to the drain region, the channel region having a substantially uniform doping concentration;
• a first charge collection region of the body defined to adjoin the source and drain regions, and fall outside of any region lying between the source and drain regions;
• a second layer of insulation formed on the body;
• and
• a gate formed on the second layer of insulation over the channel region and a portion of the charge collection region,
• the method comprising the steps of:
• applying a negative voltage to the gate for an integration period such that a source-to-body junction and a drain-to-body junction are reverse-biased;
• collecting photons during the integration period;
• and
• applying a read-out voltage more positive than the negative voltage to the gate for a read-out period following the integration period such that the source-to-body junction is reverse-biased and the drain-to-body junction is forward-biased.

A method of forming an active pixel sensor cell on a semiconductor bulk, the method comprising the steps of:

• forming a first layer of insulation on the semiconductor bulk;
• forming a body of a first conductivity type on the first layer of insulation;
• forming spaced-apart source and drain regions of a second conductivity type in the body, the source and drain regions contacting the first layer of insulation;
• defining a channel region of the body to extend downward from a top surface of the body and from the source region to the drain region, the channel region having a substantially uniform doping concentration;
• defining a first charge collection region of the body to adjoin the source and drain regions, and fall outside of any region lying between the source and drain regions;
• forming a second layer of insulation on the body;
• and
• forming a gate on the second layer of insulation over the channel region and a portion of the charge collection region.

An array of active pixel sensor cells formed on a semiconductor bulk, the array comprising:

• a first layer of insulation formed on the semiconductor bulk;
• a body of a first conductivity type formed on the first layer of insulation;
• spaced-apart first and second source lines of a second conductivity type formed in the body to contact the first layer of insulation, the first and second source lines each having a plurality of source regions which extend away from the source lines;
• a plurality of drain regions of a second conductivity type formed in the body to contact the first layer of insulation between the first and second source lines;
• a plurality of channel regions of the body defined so that each channel region adjoins a source region and a drain region;
• a plurality of charge collection regions of the body defined so that each charge collection region adjoins a drain region and a source region, and falls outside of any region lying between the source and drain regions;
• a second layer of insulation formed on the body;
• and
• a plurality of gate lines formed on the second layer of insulation so that a first gate line is formed over a first plurality of channel regions and a portion of a first plurality of charge collection regions, and a second gate line is formed over a second plurality of channel regions and a portion of a second plurality of charge collection regions.