Method for forming dopant well and method for forming image sensor

Abstract

The invention relates to a method for forming a dopant well and a method for forming an image sensor. The method for forming the dopant well comprises the following steps: forming a silicon oxide layer on a semiconductor substrate; etching a photoresist layer and a silicon oxide layer until the layers are exposed out of the semiconductor substrate after forming the photoresist layer on the siliconoxide layer, and defining the graphics of the dopant well; incinerating the photoresist layer until the layer is exposed out of the silicon oxide layer, and increasing the key dimension of the graphics of the dopant well; taking the photoresist layer and the silicon oxide layer as masks, implanting ions into the semiconductor substrate along the increased graphics of the dopant well, and formingthe dopant well of which the depth is in graded distribution; and removing the photoresist layer and the silicon oxide layer. The invention also provides the method for forming the image sensor. The invention can uniformly control the key dimension of the dopant well and simplifies processing steps.

Description

technical field [0001] The invention relates to the field of semiconductor technology, in particular to a method for forming a doped well and an image sensor. Background technique [0002] With the continuous development of semiconductor technology, the degree of integration of semiconductor devices is also getting higher and higher. Therefore, the requirements for critical dimensions of semiconductor devices are also getting higher and higher. [0003] While controlling the critical dimensions of semiconductor devices, in order to optimize the junction depth and reduce leakage, there are also requirements for the contact area between semiconductor devices. For example, in the existing process of making photodiode doped wells for image sensors, The doped well is made into an ion depth distribution gradient to increase the contact area with the semiconductor substrate, that is, the PN junction area, thereby increasing the junction capacitance, increasing the resistance, impro...

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Problems solved by technology

[0008] In the prior art, when the first ion implantation is performed on the semiconductor substrate, the ions will react with the sidewall of the photoresist layer of the opening pattern of the first ion implantation to form a hardened substance different in nature from the photoresist layer, When the photoresist layer is subsequently ashed with oxygen to increase the critical dimension of the opening pattern of the first ion implantation, the increase of the critical dimension is difficult to control

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