Tuesday, December 31, 2019

Over 90% QE Soft-X-ray CMOS Sensor

Japanese Applied Physics Express Journal publishes a paper "High-exposure-durability, high-quantum-efficiency (>90%) backside-illuminated soft-X-ray CMOS sensor" by Tetsuo Harada, Nobukazu Teranishi, Takeo Watanabe, Quan Zhou, Jan Bogaerts, and Xinyang Wang from University of Hyogo, Shizuoka University, and Gpixel.

"We develop a high-quantum-efficiency, high-exposure-durability backside-illuminated CMOS image sensor for soft-X-ray detection. The backside fabrication process is optimized to reduce the dead-layer thickness, and the Si-layer thickness is increased to 9.5 μm to reduce radiation damage. Our sensor demonstrates a high quantum efficiency of greater than 90% in the photon-energy range of 80–1000 eV. Further, its EUV-regime efficiency is ~100% because the dead-layer thickness is only 5 nm. The readout noise is as low as 2.5 e− rms and the frame rate as high as 48 fps, which makes the device practical for general soft X-ray experiments.

...we developed a new CMOS sensor with further improvements to the backside process to afford a thicker Si layer of 9.5 μm; we called this sensor the SP3 sensor. This soft-X-ray/EUV-regime SP3 image sensor is also based on the Gpixel BSI CMOS image sensor, GSENSE400SQBSI. ...We made two changes to the backside fabrication process for the SP3 relative to the SBSA: the silicon thickness was changed from 3.5 to 9.5 μm to suppress radiation damage, and that the implantation energy was decreased by one digit to reduce the non-sensitive-layer thickness. Our CMOS sensor adopts a rolling shutter and a high dynamic range (HDR) scheme using the double-conversion gain method, and has 2048 (H) × 2048 (V) 11 μm pixels.

Thanks to NT for the link!

IEDM 2019: Sony 3-Layer Organic+Si Sensor

Sony IEDM 2019 paper "Three-layer Stacked Color Image Sensor With 2.0-μm Pixel Size Using Organic Photoconductive Film" by H. Togashi, T. Watanabe, M. Joei, T. Hayashi, S. Hirata, S. Fukuoka, Y. Ando, Y. Sato, J. Yamamoto, I. Yagi, M. Murata, M. Kuribayashi, F. Koga, T. Yamaguchi, Y. Oike, T. Ezaki, and T. Hirayama combines 3T organic PD pixel with 4T Si-based pixel ideas:

"A three-layer stacked color image sensor was formed using an organic film. The sensor decreases the false color problem as it does not require demosaicing. Furthermore, with the 2.0-μm pixel image sensor, improved spectral characteristics owing to green adsorption by the organic film above the red/blue photodiode, were successfully demonstrated."

Monday, December 30, 2019

Kingpak and Tong Hsing to Merge

Digitimes: Two major Taiwan-based CMOS sensor packaging companies Tong Hsing and Kingpark have agreed to merge to turn them into one of the world's largest CIS packaging houses.

Taipei Times: Tong Hsing plans to acquire all of the shares in Kingpak after its board of directors approved a share-swap deal. The companies hope to complete the deal by June 30, 2020 and expect to pursue emerging opportunities in the smartphone, ADAS, IoT, the Internet of Vehicles, VR, and AR markets, the filing said.

The two companies have little overlap in customers and products, but they are highly complementary,” Tong Hsing president Heinz Ru said at a press conference at the Taiwan Stock Exchange. Kingpak is to become a wholly owned unit of Tong Hsing and be delisted from the Taipei Exchange when the merger is completed.

IEDM 2019: Sony 48MP All-Pixel PDAF Sensor

Sony paper at IEDM 2019 presents "A 1/2inch 48M All PDAF CMOS Image Sensor Using 0.8µm Quad Bayer Coding 2×2OCL with 1.0lux Minimum AF Illuminance Level" by T. Okawa, S. Ooki, H. Yamajo, M. Kawada, M. Tachi, K. Goi, T. Yamasaki, H. Iwashita, M. Nakamizo, T. Ogasahara, Y. Kitano, and K. Tatani.

"Currently, there are two coding trends in mobile image sensors: Quad Bayer coding (QBC) and dual photodiode (DPD). QBC realizes high resolution and high dynamic range (HDR), whereas DPD achieves high phase detection auto focus (PDAF) performance. We propose a QBC with 2×2 on-chip lens (2×2OCL) architecture as a potential next-generation high-performance CMOS image sensor. This combines high resolution, HDR, and high PDAF performance in one sensor. The critical issues of 2×2OCL are degradation of the resolution due to the sensitivity difference between 4 pixels under the same color filter and increasing the crosstalk among different colors. To overcome these issues, the OCL and pixel isolation shapes were optimized respectively. The world`s first image sensor using 2×2OCL architecture we prepared in this paper, has 1/2 inch 48M pixels with 0.8µm QBC for high resolution, and all pixel PDAF achieved a minimum AF illuminance level of 1 lux."

Sunday, December 29, 2019

PDAF Pixel Analysis

OSA Optics Express publishes an open access paper "Joint electromagnetic and ray-tracing simulations for quad-pixel sensor and computational imaging" by Guillaume Chataignier, Benoit Vandame, and Jérôme Vaillant from InterDigital and University Grenoble Alpes, France.

"Since Canon released the first dual-pixel autofocus in 2013, this technique has been used in many cameras and smartphones. Quad-pixel sensors, where a microlens covers 2x2 sub-pixels, will be the next development. In this paper we describe the design for such sensors; related wave optics simulations; and results, especially in terms of angular response. Then we propose a new method for mixing wave optics simulations with ray tracing simulations in order to generate physically accurate synthetic images. Those images are useful in a co-design approach by linking the pixel architecture, the main lens design and the computer vision algorithms."

DIY Image Sensor

Instructables publish a Sean Hodgins' project on DIY 32 x 32 image sensor and a camera based on it:

TSR Market Data

BusinessKorea quotes TSR report on image sensor market:

"According to market research firm TSR, the global image sensor market is expected to have grown from US$13,116 million to US$15,883.9 million this year. At present, the market shares of Sony, Samsung Electronics and SK Hynix are 48.3 percent, 21 percent and 2.1 percent, respectively. The current market size is about 25 percent of the size of the NAND flash market and the former is predicted to catch up with the latter in the near future.

In the third quarter of this year, Sony was the world’s eighth-largest semiconductor company in terms of sales despite the fact that image sensors are almost the only semiconductor product it produces.

Toshiba Teli on Machine Vision Sensor Trends

Toshiba Teli publishes a presentation on trends in machine vision cameras:

Saturday, December 28, 2019

IEDM 2019: Omnivision 2.2um GS BSI Pixel

Omnivision's IEDM 2019 paper "A 2.2µm stacked back side illuminated voltage domain global shutter CMOS image sensor" by Geunsook Park, Alan Chih-Wei Hsuing, Keiji Mabuchi, Jingming Yao, Zhiqiang Lin, Vincent C. Venezia, Tongtong Yu, Yu-Shen Yang, Tiejun Dai, and Lindsay A. Grant presents the world's smallest GS pixel that appears to be optimized for 940nm structured light 3D vision applications:

"This paper presents a 2.2µm pixel pitch back side illuminated (BSI) Voltage Domain Global Shutter (VDGS) image sensor with Stacked Pixel Level Connection (SPLC) and full backside Deep Trench Isolation (DTI). With these cutting edge technologies, Full Well Capacity (FWC) more than 12,000 electrons and parasitic light sensitivity (PLS) larger than 100 dB are reached. A 38% Quantum Efficiency (QE) and 60% of Modulation Transfer Function (MTF) at 940nm, half Nyquist frequency (Ny/2) is demonstrated."

Friday, December 27, 2019

IEDM 2019: Samsung 64MP Sensor with 0.8um Dual CG Pixel

Samsung IEDM 2019 paper "A 0.8 µm Smart Dual Conversion Gain Pixel for 64 Megapixels CMOS Image Sensor with 12k e- Full-Well Capacitance and Low Dark Noise" by Donghyuk Park, Seung-Wook Lee, Jinhwa Han, Dongyoung Jang, Heesang Kwon, Seungwon Cha, Mihye Kim, Haewon Lee, Sungho Suh, Woong Joo, Yunki Lee, Seungjoo Nah, Heegeun Jeong, Bumsuk Kim, Sangil Jung, Jesuk Lee, Yitae Kim, Chang-Rok Moon, and Yongin Park presents the company's latest generation sensor:

"A 0.8 μm-pitch 64 megapixels ultra high resolution CMOS image sensor has been demonstrated for mobile applications for the first time. Full-well capacity (FWC) of 6k e- was achieved in 0.8 μm pixels as the best in the world, and the advanced color filter (CF) isolation technology was introduced to overcome sensitivity degradation. Dual conversion gain (CG) technology was also first applied to mobile applications to improve the FWC performance of Tetracell up to 12k e-. In addition, highly refined deep trench isolation (DTI) and photodiode design significantly improved dark noise characteristics."

Thursday, December 26, 2019

LiDAR News: Livox, Velodyne

Livox announces long range 260m Horizon and 500m Tele-15 LiDARs:

Velodyne publishes a white paper "LiDAR-based Security Solutions" saying that one of the key LiDAR advantages over camera is privacy:

"With increased concerns that facial-recognition technology will be used for general surveillance,1 a system that utilizes lidar as the initial source of object detection data enables a security solution that preserves trust and anonymity. This is especially important in applications involving the general public, such as retail monitoring and queue management."

MicrocontrollerTips publishes a 4-part review "LIDAR and Time of Flight" by Bill Schweber. Few quotes:

Wednesday, December 25, 2019

Tuesday, December 24, 2019

Assorted News: Goodix, Sony

Digitimes: Goodix is to become the largest TSMC customer for its 8-inch fabs, thanks to its burgeoning business of under-display optical fingerprint sensors.

Sony opens Osaka-area design center for CMOS image sensors on April 1, 2020. "With the opening of the Osaka office, Sony has strengthened its CMOS image sensor design and development capabilities for mobile devices and the IoT market, which are expected to expand in the future, by acquiring talented analog and logic design engineers in Kansai. We aim to expand our product lineup."

Bloomberg reports that Sony has hard time manufacturing enough image sensors to keep up with high demand.

"For the second straight year, the Japanese company will run its chip factories constantly through the holidays to try and keep up with demand for sensors used in mobile phone cameras, according to Terushi Shimizu, the head of Sony’s semiconductor unit.

“Judging by the way things are going, even after all that investment in expanding capacity, it might still not be enough,” Shimizu said in an interview at the Tokyo headquarters. “We are having to apologize to customers because we just can’t make enough.”

Sony in May said it controls 51% of the image sensor market as measured by revenue and is targeting a 60% share by fiscal 2025. Shimizu estimates Sony’s portion of the pie grew by a few percentage points this year alone.

Sony is now looking to a new generation of sensors that can see the world in three dimensions. “This was the year zero for time of flight,” Shimizu said. “Once you start seeing interesting applications of this technology, it will motivate people to buy new phones.

Sony’s ToF camera module.Photographer: Kiyoshi Ota/Bloomberg

4-Tap ToF Pixel for LiDAR Applications

MDPI paper "A Time-of-Flight Range Sensor Using Four-Tap Lock-In Pixels with High near Infrared Sensitivity for LiDAR Applications" by Sanggwon Lee, Keita Yasutomi, Masato Morita, Hodaka Kawanishi, and Shoji Kawahito from Shizuoka University, Japan promises enhanced range and ambient light tolerance:

"In this paper, a back-illuminated (BSI) time-of-flight (TOF) sensor using 0.2 µm silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) technology is developed for long-range laser imaging detection and ranging (LiDAR) application. A 200 µm-thick bulk silicon in the SOI substrate is fully depleted by applying high negative voltage at the backside for higher quantum efficiency (QE) in a near-infrared (NIR) region. The proposed SOI-based four-tap charge modulator achieves a high-speed charge modulation and high modulation contrast of 71% in a NIR region. In addition, in-pixel drain function is used for short-pulse TOF measurements. A distance measurement up to 27 m is carried out with +1.8~−3.0% linearity error and range resolution of 4.5 cm in outdoor conditions. The measured QE of 55% is attained at 940 nm which is suitable for outdoor use due to the reduced spectral components of solar radiation."