Pixel structure and preparation method of a stacked image sensor

Abstract

The invention discloses a stacked mage sensor pixel structure and a fabrication method thereof. A first silicon wafer, a second silicon wafer and a third silicon wafer are vertically stacked by a bonding mode, wherein the first silicon wafer and the second silicon wafer are respectively formed from a remaining upper-layer thin bulk silicon substrate after a SiO2 layer and a lower-layer thick bulksilicon substrate of a standard SOI silicon wafer are stripped, a first light-sensitive diode array is arranged on the first silicon wafer, a second light-sensitive diode array is arranged on the second silicon wafer, a surface of each second light-sensitive diode is aligned and bonded with a surface of each corresponding first light-sensitive diode, so that the formed stacked image sensor chip has a junction which can be deepen to a SiO2 layer of the SOI silicon wafer, a dark current is better, the quantum efficiency can be effectively improved at a near-infrared band, the sensitivity is relatively high, a filling factor is relatively high, a very good comprehensive effect such as light-sensitive performance can be achieved for a small-size pixel element, the near-infrared quantum efficiency is compatible, and the small pixel size is also compatible.

Description

technical field [0001] The present invention relates to the technical field of image sensors, and more particularly, to a stacked near-infrared image sensor pixel structure and a preparation method thereof. Background technique [0002] Image sensors are an important part of digital cameras. According to the different components, it can be divided into two categories: CCD (Charge Coupled Device, charge-coupled device) and CMOS (Complementary Metal-Oxide Semiconductor, metal oxide semiconductor device). A prerequisite for the wide application of CMOS sensors is their higher sensitivity, shorter exposure time and shrinking pixel size. [0003] Among them, pixel sensitivity, one of the important performance indicators of CMOS image sensors, is mainly determined by the product of fill factor (the ratio of photosensitive area to the entire pixel area) and quantum efficiency (the number of electrons generated by photons bombarding the screen). In CMOS image sensors, in order to ...

AI Technical Summary

Problems solved by technology

Due to the influence of the pre-process, it is usually impossible to achieve a deep junction depth, and it cannot have a good sensitivity to near-infrared or quantum efficiency.

Images