Image sensor cells

A semiconductor structure fabrication method, comprising the steps of:

• (a) providing a semiconductor substrate;
• (b) forming a charge collection well in the semiconductor substrate, the charge collection well comprising a first semiconductor material doped with a first doping polarity;
• (c) forming a surface pinning layer on and in direct physical contact with the charge collection well, the surface pinning layer comprising a second semiconductor material doped with a second doping polarity opposite to the first doping polarity;
• (d) forming a cushion region in the semiconductor substrate so as to push the charge collection well to a sufficient distance from where an electrically conducting push electrode is to be formed such that the electrically conducting push electrode can be later formed not in direct physical contact with the charge collection well;
• and
• (e) forming the electrically conducting push electrode being in direct physical contact with the surface pinning layer but not in direct physical contact with the charge collection well.

A semiconductor structure fabrication method, comprising the steps of:

• (a) providing a semiconductor substrate;
• (b) forming a charge collection well in the semiconductor substrate, the charge collection well comprising a first semiconductor material doped with a first doping polarity;
• (c) forming a surface pinning layer on and in direct physical contact with the charge collection well, the surface pinning layer comprising a second semiconductor material doped with a second doping polarity opposite to the first doping polarity;
• (d) forming a cushion region in the semiconductor substrate so as to push the charge collection well to a sufficient distance from where an electrically conducting push electrode is to be formed such that the electrically conducting push electrode can be later formed not in direct physical contact with the charge collection well;
• and
• (e) forming the electrically conducting push electrode being in direct physical contact with the surface pinning layer but not in direct physical contact with the charge collection well,
• wherein the cushion region is doped with a dopant concentration sufficient to create a depletion region in the charge collection well, and
• wherein the depletion region in the charge collection well physically separates the charge collection well into first and second charge collection regions.