Near Ultraviolet Photocell
AssigneeSTMicroelectronics (Research & Development) Limited
InventorJeffrey M. Raynor
Life of this patent
Estimating the term…
Abstract
In an embodiment, an image sensor includes a semiconductor substrate, an epitaxial layer disposed over the semiconductor substrate, a first heavily doped region disposed in the epitaxial layer, and a shallow trench isolation region disposed in the epitaxial layer and surrounding the first heavily doped region. The semiconductor substrate and the epitaxial layer are of a first doping type and the semiconductor substrate is coupled to a reference potential node. The first heavily doped region is of a second doping type opposite to the first doping type. The epitaxial layer, the first heavily doped region, and the shallow trench isolation region are part of a p-n junction photodiode configured to operate in the near ultraviolet region.
Claims37
An image sensor comprising:
- a semiconductor substrate of a first doping type, the semiconductor substrate coupled to a reference potential node;
- an epitaxial layer of the first doping type disposed over the semiconductor substrate;
- a first heavily doped region of a second doping type disposed in the epitaxial layer, the second doping type being opposite to the first doping type;
- a first guard region of the first doping type disposed in the epitaxial layer;
- and
- a shallow trench isolation region disposed in the epitaxial layer, in contact with the first guard region, and surrounding the first heavily doped region, wherein the epitaxial layer, the first heavily doped region, and the shallow trench isolation region are part of a p-n junction photodiode surrounded by the first guard region, and wherein the p-n junction photodiode is configured to operate in the near ultraviolet region.
(canceled)
An image sensor comprising:
- a semiconductor substrate of a first doping type, the semiconductor substrate coupled to a reference potential node;
- an epitaxial layer of the first doping type disposed over the semiconductor substrate;
- a first heavily doped region of a second doping type disposed in the epitaxial layer, the second doping type being opposite to the first doping type, wherein the epitaxial layer and the first heavily doped region are part of a p-n junction photodiode, and wherein the p-n junction photodiode is configured to operate in the near ultraviolet region;
- and
- a well region of the first doping type disposed in the epitaxial layer, wherein the first heavily doped region and the well region form a p-n junction of the p-n junction photodiode.
(canceled)
A method of operating an image sensor, the method comprising:
- providing a photodiode comprising:
- an epitaxial layer of a first doping type disposed over a semiconductor substrate;
- a first heavily doped region of a second doping type disposed in the epitaxial layer, the second doping type being opposite to the first doping type;
- a second heavily doped region of the second doping type disposed in the epitaxial layer, the second heavily doped region laterally spaced from the first heavily doped region;
- and
- a shallow trench isolation region disposed in the epitaxial layer and surrounding the first heavily doped region;
- applying bias to set the photodiode under reverse bias;
- exposing the photodiode to a photon having a wavelength in the near ultraviolet range;
- generating an electron-hole pair in the photodiode;
- transferring an electron or a hole of the electron-hole pair to a connector node;
- and
- converting the charge of the electron or the hole collected at the connector node to a read voltage.
Dependencies are inferred from the claim text.