Image sensor forming method and image sensor

Abstract

The invention provides an image sensor forming method and a formed image sensor, and the method comprises the steps: forming a first lateral PN junction through at least one etching process and at least one epitaxial process before a grid electrode of the image sensor is formed, and the first lateral PN junction is used for isolating pixel units of the image sensor. According to the invention, the isolation region and the photosensitive region in the image sensor are formed by adopting etching and epitaxial processes, and the lateral PN junction is formed, so that the interface of the P-type semiconductor and the N-type semiconductor is more uniform, the damage to the semiconductor substrate caused by adopting a mode of ion implantation for multiple times can be avoided, and the influence of dark current and white pixels on light sensing is reduced.

Description

technical field [0001] The present invention relates to the technical field of semiconductors, and in particular, to a method for forming an image sensor and an image sensor. Background technique [0002] In order to improve the resolution of the image sensor, it is necessary to improve the extraction capability of electrons as much as possible, so it is necessary to increase the volume and electron concentration of the sensor semiconductor substrate. On this basis, in order to reduce the surface area of ​​the chip, increasing the depth of the semiconductor substrate has become the preferred solution. [0003] The semiconductor substrate of an image sensor usually includes several isolation regions. Among the existing semiconductor substrate formation methods, shallow trench isolation is a common method. However, shallow trench isolation cannot meet the requirements of deep semiconductor substrates. Therefore, The use of ion implantation, or a combination of ion implantatio...

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Problems solved by technology

[0003] The semiconductor substrate of an image sensor usually includes several isolation regions. In the existing semiconductor substrate formation methods, shallow trench isolation is a relatively common method. However, shallow trench isolation cannot meet the requirements of a deep semiconductor substrate. Therefore, Ion implantation, or a combination of ion implantation and shallow trench isolation, is used to form isolation regions

[0004] However, it is still very difficult to achieve deep isolation. Generally, multiple ion implantations are required. The damage of ion implantation to the semiconductor substrate will affect the dark current and white pixels. The ion-implanted P-type semiconductor and the N-type semiconductor in the substrate The sudden change of the semiconductor at the critical surface makes the electric field strength at this place higher; in addition, multiple ion implantation makes the concentration distribution very uneven in depth, and the electronic potential barrier generated by the rough concentration change will make electrons gather here. difficult to extract completely

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