Technology overview: BSI sensor (BackSide Illuminated Image Sensors)

Backside illumination image sensors stand out due to their increased image quality and have become an indispensable part of consumer electronics and smartphones. With the introduction of a wafer-to-wafer (W2W) process, the Fraunhofer IMS has reached a new level of technology which enables the generation of high-quality BSI sensors. Initially, photodetectors and the associated read-out circuit are produced separately on 8-" wafer. Subsequently, both wafer are permanently connected. Compact structures with the shortest electrical connections are created.

This heterointegration is used particularly in the production of high-quality 3D sensors with SPADs (Single Photon Avalanche Diode). The highly sensitive photodiodes allow high measuring ranges for the detection of object distances and are therefore used in sensors for autonomous driving. As BSI SPAD, large 2D matrices can be generated, which have very high fill factors of up to 70%. This provides, for example, enormous advantages in the use of sensor systems in traffic.

At Fraunhofer IMS, the entire process chain for the manufacture of the sensors is shown. Engineers with experience in CMOS and / or MEMS processes are supported by their colleagues in assembly and connection technology, circuit design and test. The interaction of all areas in one location is a unique selling proposition for the location of the Fraunhofer IMS.

The independent fabrication of readout circuitry and photodetector allows an optimal selection of wafer material in terms of sensor requirements. 8-" wafer from our CMOS line or from external semiconductor manufacturers can be integrated with the photodetectors. The Fraunhofer IMS uses a 0.35 μm OPTO process and can rely on more than 30 years of CMOS experience.

Contact our competent consultant and take a look into the world of BSI sensors from Fraunhofer IMS!

© Fraunhofer IMS