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Method of forming an angled pinned photodiode for high quantum efficiency

a photodiode and quantum efficiency technology, applied in the field of semiconductor devices, can solve the problems of poor signal to noise ratio, strong influence on the magnitude of dark current generated, and poor dynamic range of cmos imagers

Inactive Publication Date: 2005-05-12
MICRON TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0015] In one aspect, the invention provides a pinned photodiode with a pinned layer laterally displaced from an electrically active area of a transfer gate of a pixel sensor cell by a predetermined distance. The pinned layer is in contact with a charge collection region formed by an angled implant. The angle of the charge collection region implant may be tailored so that the charge collection region contacts an adjacent edge of the transfer gate of the pixel sensor cell and minimizes, therefore, the gate overlap region and the undesirable barrier potential.

Problems solved by technology

In addition, defects and trap sites inside or near the photodiode depletion region strongly influence the magnitude of dark current generated.
CMOS imagers also typically suffer from poor signal to noise ratios and poor dynamic range as a result of the inability to fully collect and store the electric charge collected in the region 26.

Method used

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  • Method of forming an angled pinned photodiode for high quantum efficiency
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  • Method of forming an angled pinned photodiode for high quantum efficiency

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Embodiment Construction

[0037] In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized, and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention.

[0038] The terms “wafer” and “substrate” are to be understood as a semiconductor-based material including silicon, silicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology, doped and undoped semiconductors, epitaxial layers of silicon supported by a base semiconductor foundation, and other semiconductor structures. Furthermore, when reference is made to a “wafer” or “substrate” in the following description, previous process steps may have be...

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PUM

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Abstract

A pinned photodiode with a surface layer of a first conductivity type laterally displaced from an electrically active area of a gate structure and a charge collection region of a second conductivity type formed by an angled implant is disclosed. The angle of the charge collection region implant may be tailored so that the charge collection region contacts an adjacent edge of the transfer gate of the pixel sensor cell and minimizes, therefore, the gate overlap region and an undesirable barrier potential.

Description

FIELD OF THE INVENTION [0001] The present invention relates to the field of semiconductor devices and, in particular, to improved photodiodes for high quantum efficiency. BACKGROUND OF THE INVENTION [0002] The semiconductor industry currently uses different types of semiconductor-based imagers, such as charge coupled devices (CCDs), photodiode arrays, charge injection devices and hybrid focal plane arrays, among others. [0003] Because of the inherent limitations and expense of CCD technology, CMOS imagers have been increasingly used as low cost imaging devices. A CMOS imager circuit includes a focal plane array of pixel cells, each one of the cells including either a photodiode, a photogate or a photoconductor overlying a doped region of a substrate for accumulating photo-generated charge in the underlying portion of the substrate. A readout circuit is connected to each pixel cell and includes a charge transfer section formed on the substrate adjacent the photodiode, photogate or ph...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01L27/146
CPCH01L27/14609H01L27/14603H01L27/146
Inventor RHODES, HOWARD E.
Owner MICRON TECH INC