Making large pixels fast, insights from X-FAB

Xuezhou Cao, Process Development Analog and Sensor Group Manager at X-FAB Semiconductor Foundaries spoke to us ahead of Image Sensors Europe 2018 about new pixel testing and insights on why large pixels need to be made faster.

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1.Your presentation looks at ‘how to make large pixels fast’, why is this important for the image sensors industry?

First of all, large is a relative term. Comparing with pixels used by mobile phones, 3um or 5um pixels are already considered large. On another hand, for many scientific and medical applications, the pixel size can be up to 100um or even 200um large. For low lighting image or high speed applications, larger pixels are needed. For low lighting imaging application, such as medical X-ray application due to low dose requirement, pixels with high sensitivity are needed, thus larger size pixels are necessary. For high speed imaging application, due to the very short exposure time, larger size pixels are also required to enhance the sensitivity.

2.You’re going to be exploring new pixel test results, can you give us an insight into what this will include?

X-FAB has previously published results on different 50um 4T pixel designs and their impact on image lag.

We have now designed our own test chips and have investigated the impact of different 4T pixel design & sizes, different pinning voltage on various pixel parameters, such as Fullwell capacity, conversion gain, dark current, image lag etc. This will help our customers to select the right pixel design and process modules to best match their particular requirement.

3.What can the attendees look to gain by hearing your presentation at the conference?

The attendee can gain information on X-FAB foundry offering on Opto and CIS, learn X-FAB CIS capability and performance, and also gain some understanding on various design consideration and trade-off for large 4T pixel design.  

4.What are you most looking forward to by attending the conference in 2018? 

Image Sensor Europe has become one of the popular forums for CIS experts and practitioners to gather.  I look forward to meet our friends, customers and other like-minded professionals to exchange ideas and information, to learn about the new developments and trends in CIS area.