Pixel sensor cell having a pinning layer surrounding collection well regions for collecting electrons and holes
View Patent ↗The present invention is a pixel sensor cell and method of making the same. The pixel sensor cell approximately doubles the available signal for a given quanta of light. The device of the present invention utilizes the holes produced by impinging photons in a pixel sensor cell circuit. A pixel sensor cell having reduced complexity includes an n-type collection well region formed beneath a surface of a substrate for collecting electrons generated by electromagnetic radiation impinging on the pixel sensor cell and a p-type collection well region formed beneath the surface of the substrate for collecting holes generated by the impinging photons. A circuit structure having a first input is coupled to the n-type collection well region and a second input is coupled to the p-type collection well region, wherein an output signal of the pixel sensor cell is the magnitude of the difference of a signal of the first input and a signal of the second input.
1. A pixel sensor cell comprising:
an n-type collection well region formed in a substrate for collecting electrons generated by electromagnetic radiation impinging on said pixel sensor cell;
a p-type collection well region formed in said substrate for collecting holes generated by said impinging electromagnetic radiation;
a pinning layer formed substantially surrounding said n-type and p-type collection well regions; and
a circuit structure having a first input coupled to said n-type collection well region and a second input coupled to said p-type collection well region, wherein an output signal of said pixel sensor cell being the magnitude of the difference of a signal of said first input and a signal of said second input.
2. The pixel sensor cell of claim 1 further comprising:
an n-type diffusion region formed in direct physical contact with said n-type collection well region; and
a p-type diffusion region formed in direct physical contact with said p-type collection well region.
3. The pixel sensor cell of claim 2 , wherein said n-type diffusion region is coupled to said first input of said circuit structure and said p-type diffusion region is coupled to said second input of said circuit structure.
4. The pixel sensor cell of claim 1 , wherein said circuit structure comprises a differential amplifier circuit having a negative input terminal coupled to said first input of said circuit structure and a positive input terminal coupled to said second input of said circuit structure.
5. The pixel sensor cell of claim 4 , wherein an output of said differential amplifier circuit provides said output signal of said pixel sensor cell.
6. The pixel sensor cell of claim 1 , wherein said first input signal is opposite to said second input signal.
7. The pixel sensor cell of claim 1 , wherein said n-type collection well region and said p-type collection well region are formed in a vertical arrangement in said substrate.
8. The pixel sensor cell of claim 1 further comprising a pinning layer formed in an upper surface of said substrate.