Backside illuminated image sensor

Abstract

The invention discloses a backside illuminated image sensor, which comprises an image sensor chip and a support substrate, wherein a bonding pad is embedded on the front surface of the image sensor chip; insulating layers respectively coat the front surface of the image sensor chip and the top surface of the support substrate; the image sensor chip and the support substrate are in bonding connection through a bonding layer; the thickness of the image sensor chip is 15-20 microns; a P-type injection layer is arranged on the back surface of the image sensor chip; an anti-reflection film layer is arranged on the back surface of the image sensor chip; a reflecting film layer for releasing a photo-induction element zone is arranged on the upper surface of the anti-reflection film layer; a window for releasing the bonding pad is also arranged on the back surface of the image sensor chip; and the image sensor chip and the support substrate are in bonding connection through the bonding layer, and have good thermal matching property and reliability. Through treatment on the back surface of the image sensor chip, the quantum efficiency is improved. The backside illuminated image sensor is simple in overall structure, low in stress, high in reliability and simple in bonding pad release structure; and subsequent package can be achieved by a conventional wire bonding technology.

Description

technical field [0001] The invention relates to a back-illuminated image sensor. Background technique [0002] As is known, image sensors generally include front-illuminated and back-illuminated types. The front-illuminated type receives images on the front side of the semiconductor substrate of the image sensor, and the light passes through the circuit layer to the photodetection area. Due to the influence of reflection, the quantum efficiency of the front-illuminated image sensor is low, usually less than 50%, especially for short-wavelength bands, such as below 400nm, the photosensitive response will be cut off. This defect can be avoided by the back-illuminated image sensor. The back-illuminated type means that the light is incident from the front of the image sensor to the back. Since the light does not need to pass through the circuit layer when it is incident, it can improve the spectral response range and quantum efficiency of the image sensor. , the peak can reach ...

AI Technical Summary

Problems solved by technology

The patent document "Partial Thinning Back-illuminated Image Sensor Structure and Packaging Technology" (publication number CN103996687A) discloses a back-illuminated image sensor. The mechanical stress of the local thinning structure of the sensor is relatively large. The lead connection of the disk is an unconventional structure, and it is not easy to implement in batches in the subsequent packaging process; the patent document "Low Cost, Highly Integrated Back-illuminated Image Sensor Package" (authorized announcement number CN102751299B) discloses a back-illuminated image sensor Sensor, the sensor also adopts a cavity structure, but the cavity size in the cavity structure is large, the thickness of the bottom of the cavity is very thin, and the height of the side wall is much larger than the thickness of the bottom. This structure will have the problem of large mechanical stress. On the other hand The follow-up use of the device generally adopts flip-chip interconnection, and the uneven filling in the flip-chip process may cause reliability problems; CN102891151B) discloses a back-illuminated image sensor. Although the sensor has the advantage of low stress, the pad release structure is relatively complicated, and the inhomogeneity of the filling material may also have a certain impact on the performance of the device. There are certain reliability issues

At present, there is no back-illuminated image sensor structure with simple overall structure, low stress, good reliability, simple pad release and packaging interconnection process, and high quantum efficiency.

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