Low-dark-current image sensor pixel structure

Abstract

The invention discloses a low-dark-current image sensor pixel structure. The low-dark-current image sensor pixel structure comprises a photosensitive diode, a negative charge fixing dielectric layer,a suspension drain region, a transmission tube grid and a side wall of the transmission tube grid which are arranged in a semiconductor substrate. The negative charge fixing layer is composed of an oxide layer with a high dielectric constant (k), the oxide layer with a high k value can be made of Al2O3, HfO2, Ta02 and other materials, and the oxide layer with the high k value is deposited on the surface of PD silicon and the surface of silicon below a transmission grid of the PD silicon and makes direct contact with the surface of the silicon to form a Si-O interface. The oxide layer with thehigh k value generates interface energy for constraining electrons on the Si-O interface, and the interface energy effectively constrains the surface of the photodiode and electrons generated by unsaturated dangling bonds of a transmission tube channel and defects so that a dark current is effectively reduced.

Description

technical field [0001] The invention relates to an image sensor pixel structure, in particular to an image sensor pixel structure with low dark current. Background technique [0002] Image sensor pixels are semiconductor devices commonly used at present, which can convert the light image on the photosensitive surface into electrical signals proportional to the light image, and are widely used in various industries. [0003] In the prior art, the image sensor pixel structure is as figure 1 As shown, it includes: silicon substrate Silicon101, photodiode PD (photodiode) 102, gate oxide layer (oxide) 103, floating drain region FD (Floating Drain) 104, transmission tube gate (TX Gate) 105 and its sidewall (spacer) )106. [0004] There are at least the following disadvantages in the above-mentioned prior art: [0005] It is difficult for the gate oxide layer (oxide) to effectively bind the electrons generated by the unsaturated dangling bonds and defects on the surface of the p...

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Problems solved by technology

[0005] The gate oxide layer (oxide) is difficult to effectively bind the electrons generated by the unsaturated dangling bonds and defects on the surface of the photodiode and its transmission channel, resulting in the generation of dark current

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