Howard Rhodes (Omnivision) : “Second Generation 65 nm OmniBSI CMOS Image Sensors”.
(The presentation of Howard was not available at the moment of presentation, so what you find here is what was learned only from his oral presentation.)
The development of BSI at Omnivision started in 2006 on a 2.2 um pixel, in May 2007 the BSI was applied already in a 0.11 um technology. The first public announcements of the OmniBSI technology were done in May 2008 (on a 1.75 um pixel) and first mass production started early 2009.
At this moment OmniVision has about 15 different BSI devices in production, all fabricated on bulk silicon with a p+ back-side passivation. Why not SOI ? Because there is no significant improvement in final thickness control, SOI is expensive and the worldwide supply of SOI is limited. Process flow for the bulk silicon process : p/p+ wafer, frontside processing, wafer bonding, wafer thinning, BSI process, CFA alignment and microlens alignment, bondpad etch.
A lot of data was shown for 1.4 um and 1.75 um pixels made in the first generation of the BSI technology, this data was already presented earlier at IISW2009 : SNR10 for 1.4 um : 88 lux, SNR10 for 1.75 um : 53 lux.
OmniBSI-2 was announced in Feb. 2010 and products are out at this moment, in the mean time OmniBSI-3 is being developed. OmniBSI-2 is concentrating on a 65 nm Cu CMOS technology node. Advantages of OmniBSI-2 are : better design rules allowing bigger collection regions in the photodiode (QE, cross-talk, full-well, PRNU, higher SNR), new pixel design improvements, new process modules. For a 1.75 um pixel the SNR10 is improved to 41 lux with the Omni-BSI-2 process, for a 1.4 um pixel the SNR10 is improved to 58.5 lux. The SNR10 for the 1.1 um was reported to be 117 lux. OmniBSI-2 is running on 300 mm wafers, whereas the OmniBSI-1 was using 200 mm wafers.
OmniBSI-3 will focus on 40 nm design rules with all kind of improvements for the pixels as well as a new colour filter technology.
York Haemisch (Philips Digital Photon Counting) : “Fully digital light sensors enabling true photon counting with temporal and spatial resolution”.
Old fashioned PMTs are being replaced by Silicon PMTs, based on avalanche PD biased in Geiger mode. Status of the SiPMT work at Philips : 8 x 8 digital SiPMs with 6400 diodes (cells) per pixel on 11 cm2 area are available, and the components can be tilled in 4 directions. In a new generation, an FPGA will be added to the system that allows corrections and signal processing as close as possible to the sensor die. Also this presentation showed a lot of performance data and details about the measurements made.
So far an outstanding timing resolution is measured (ideal for ToF), a lower dark count level than analog systems is reported and the systems are very robust (sensitivity does hardly change with temperature, insensitivity to electromagnetic interference). First application field is nuclear imaging for medical applications, next other medical imaging can/will be targeted and ultimately analytical instrumentation as well.
Albert 24-03-2011.
Hello Albert,
Thank you for the excellent coverage of IISW. For Omni’s BSI talk, was an integration time provided for the SNR10 lux values?
Thanks,
Hi, I reported about ISE and not IISW, that one has still to come 😉
I do not know the integration time for the SNR10 spec. I cannot remember I have seen any data on that. At this moment the presentation of Howard is not (yet) available to check the data.
The frame rate is fixed to 15fps for SNR10 measurement if OV used Nokia standard test.