Band gap modulated optical sensor
AssigneeInternational Business Machines Corporation
InventorsKangguo Cheng, Toshiharu Furukawa, Robert Robison, William R. Tonti
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Abstract
A complementary metal-oxide-semiconductor (CMOS) optical sensor structure includes a pixel containing a charge collection well of a same semiconductor material as a semiconductor layer in a semiconductor substrate and at least another pixel containing another charge collection well of a different semiconductor material than the material of the semiconductor layer. The charge collections wells have different band gaps, and consequently, generate charge carriers in response to light having different wavelengths. The CMOS sensor structure thus includes at least two pixels responding to light of different wavelengths, enabling wavelength-sensitive, or color-sensitive, capture of an optical data.
Claims20
A method of forming a semiconductor structure comprising:
- providing a semiconductor substrate including a semiconductor layer comprising a first semiconductor material and having a doping of a first conductivity type;
- forming a first photosensitive diode in said semiconductor substrate, wherein said first photosensitive diode comprises a first charge collection well and a first semiconductor portion that is a portion of said semiconductor layer, wherein said first semiconductor portion is formed directly underneath said first charge collection well, comprises said first semiconductor material, and has a doping of said first conductivity type, wherein said first charge collection well comprises said first semiconductor material and has a doping of a second conductivity type, wherein said second conductivity type is the opposite of said first conductivity type;
- and
- forming a second photosensitive diode in said semiconductor substrate, wherein said second photosensitive diode comprises a second charge collection well and a second semiconductor portion, wherein said second semiconductor portion is formed directly underneath said second charge collection well, comprises a second semiconductor material having a different composition than said first semiconductor material, has a doping of said first conductivity type, and contacts said first semiconductor material in said semiconductor layer, wherein said second charge collection well comprises said second semiconductor material and has a doping of said second conductivity type.
Dependencies are inferred from the claim text.