Back-illuminated sensor
A back-illuminated sensor, also known as backside illumination (BI) sensor, is a type of digital image sensor that uses a novel arrangement of the imaging elements to increase the amount of light captured and thereby improve low-light performance.
The technique was used for some time in specialized roles like low-light security cameras and astronomy sensors, but was complex to build and required further refinement to become widely used.
Description
A traditional, front-illuminated
A back-illuminated sensor contains the same elements, but arranges the wiring behind the photocathode layer by flipping the silicon wafer during manufacturing and then
Other advantages of a BSI sensor include wider angular response (giving more flexibility for lens design) and possibly faster readout rates. Disadvantages include worse response uniformity.
Industry observers[who?] noted that a back-illuminated sensor could theoretically cost less than a similar front-illuminated version. The ability to collect more light meant that a similarly sized sensor array could offer higher resolution without the drop in low-light performance otherwise associated with the megapixel (MP) race. Alternatively, the same resolution and low-light capability could be offered on a smaller chip, lowering costs. Key to attaining these advantages would be an improved process that addressed the yield problems, largely through improving the uniformity of an active layer on the front of the detectors.[8]
A major step in the adoption of BI sensors was made when
Sony's work on new photodiode materials and processes allowed them to introduce their first consumer back-illuminated sensor as their
In January 2012, Sony developed the back-side illuminated sensor further with Stacked CMOS,[3] where the supporting circuitry is moved below the active pixel section, giving another 30% improvement to light capturing capability.[17] This was commercialized by Sony in August 2012 as Exmor RS with resolutions of 13 and 8 effective megapixels.[18]
In October 2012, GoPro used a Sony IMX117 sensor as the first BSI sensor in their action cameras, in the Hero3 Black.[19]
In September 2014 Samsung announced the world's first
In June 2015 Sony announced the first camera employing a back-side illuminated full frame sensor, the α7R II.[3]
In August 2017
In September 2018
In April 2021, Canon announced their new R3 model would feature a 35mm full-frame, back illuminated, stacked CMOS sensor and a DIGIC X image processor.[22]
In April 2021, Ricoh released the Pentax K-3 III featuring a BSI 26 megapixel APS-C sensor from Sony and a PRIME V image processor.
In May 2021, Sony announced a new back-illuminated, stacked sensor for the Micro Four Thirds format.[23]
See also
References
- ^ a b c d Sony, 2009
- Sony Corporation
- ^ a b c d e Zimmerman, Steven (12 October 2016). "Sony IMX378: Comprehensive Breakdown of the Google Pixel's Sensor and its Features". XDA Developers. Retrieved 17 October 2016.
- ^ a b "Inside the HTC EVO 4G Smart Phone with a Teardown to the Silicon". chipworks. 4 June 2010. Archived from the original on 22 July 2011. Retrieved 3 August 2011.
- ^ Tufegdzic, Pamela (3 September 2010). "iPhone 4 Drives Adoption of BSI Image Sensors in Smart Phones". iSuppli. Archived from the original on 19 July 2011. Retrieved 3 August 2011.
- ^ Apple, 2010
- RCA Corporation
- ^ a b c Swain and Cheskis, 2008
- ^ Yoshua Goldman. "Why the iPhone 4 takes good low-light photos: BSI CMOS sensors explained!". Retrieved 29 September 2014.
- ^ Yoshida 2007
- ^ "OmniVision premieres world's first 1/3-inch, 8 megapixel CameraChip sensor with 1.4 micron OmniBSI technology". EDN. 23 September 2008.
- ^ Brian Klug (20 July 2010). "Motorola Droid X: Thoroughly Reviewed". Anandtech.
- ^ "OmniVision delivers DSC-quality imaging to high performance mobile phone market" (PDF). OmniVision. 22 June 2009.
- ^ "DSC-Quality Imaging for High-Performance Mobile Phones: OV5650 5 megapixel product brief" (PDF). OmniVision. January 2010.
- ^ Philip Berne (24 June 2010). "Review: iPhone 4". PhoneScoop.
- ^ Vlad Savov. "Sony Ericsson Xperia Arc review". Engadget. AOL. Retrieved 16 August 2015.
- ^ "Sony's Stacked CMOS Image Sensor Solves All Existing Problems in One Stroke" (PDF). Sony. 12 June 2012. Archived from the original (PDF) on 12 June 2012.
- ^ "Sony Global – News Releases – Sony Develops "Exmor RS," the World's First*1 Stacked CMOS Image Sensor". Retrieved 16 August 2015.
- ^ "GoPro HERO3 Black Edition: Super Hero..." DXOMARK. 18 July 2013. Retrieved 6 September 2022.
- ^ "Samsung Semiconductors Global Site". Retrieved 16 August 2015.
- ^ "Fujifilm announces the new X-T3, a mirrorless digital camera evolving X Series into fourth generation". Fujifilm. Retrieved 27 September 2018.
- ^ "Canon announces development of the EOS R3 full-frame mirrorless camera that delivers high speed, high sensitivity and high reliability to expand users' range of photographic possibilities". Canon. Retrieved 17 April 2021.
- ^ "Sony announced a new 20MP stacked BS1 Micro Four Thirds sensor. Is this for the future Olympus OMD camera?". Retrieved 30 May 2021.
Bibliography
- (Sony), "Sony unveils 'Exmor R' back-illuminated CMOS technology", Sony press release, 6 August 2009
- P.K. Swain and David Cheskis, "Back-Illuminated Image Sensors Come to the Forefront", Photonics, August 2008
- Junko Yoshida, "OmniVision adopts backside illumination technology for CMOS imager", EE Times, 27 May 2007
- (Apple), "iPhone 4: Camera", Apple Inc., 7 June 2010