Image sensor with improved quantum efficiency for infrared radiation
AssigneeSTMicroelectronics (Crolles 2) SAS
InventorsAxel Crocherie, Pierre Emmanuel Marie Malinge
Life of this patent
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Abstract
An integrated image sensor with backside illumination includes a pixel. The pixel is formed by a photodiode within an active semiconductor region having a first face and a second face. A converging lens, lying in front of the first face of the active region, directs received light rays towards a central zone of the active region. At least one diffracting element, having a refractive index different from a refractive index of the active region, is provided at least partly aligned with the central zone at one of the first and second faces.
Claims17
An integrated image sensor with backside illumination including at least one pixel, comprising:
- an active semiconductor region of a semiconductor substrate having a first face and a second face, the active semiconductor region containing a photodiode,
- a converging lens which lies in front of the first face of the active semiconductor region and is configured in order to direct the light rays arriving on the converging lens towards a central zone of the active semiconductor region, and
- at least one diffracting element formed by a line of polysilicon on the second face of the active semiconductor region, said line of polysilicon having a refractive index different from a refractive index of the active semiconductor region, said at least one diffracting element being at least partly aligned with the central zone.
An image sensing pixel, comprising:
- a semiconductor substrate;
- an active semiconductor region of said semiconductor substrate having a first face and a second face;
- a photodiode within the active semiconductor region;
- a converging lens which lies in front of the first face and is configured to direct received light towards the first face;
- and
- a line of polysilicon material on the second face at the active semiconductor region to form a diffracting element configured to diffract light received from the converging lens.
Dependencies are inferred from the claim text.