Samsung Electronics has launched a new advanced pixel technology for CMOS image sensors, ISOCELL. The technology substantially increases light sensitivity and effectively controls the absorption of electrons, resulting in higher colour fidelity even in poor lighting conditions. ISOCELL improves the image quality and will be used to target premium smartphones and tablets that integrate sensors with this new technology.
“Through advances in pixel and process technology, smartphone and tablet cameras have made it easier for consumers to capture and share clear images,” said Taehoon Kim, vice president of System LSI marketing, Samsung Electronics. “ISOCELL technology significantly raises the bar in image quality.”
The quality of an image sensor is determined by the amount of light that is accurately captured by the individual pixels within the sensor array. With the market pressure to increase camera resolution and image quality, without growing the camera size, the pixels have had to shrink, while improving their performance at the same time.
To meet this challenge, previous sensor technology developments focused on improving the light absorption of each pixel, and have progressed pixel technology from FSI (Front Side Illumination) to BSI (Back Side Illumination) which places photodiode at the top to maximise photoelectric efficiency. While being very effective at the time, this BSI technology also faced limitations in improving image quality as pixel sizes continued to decrease.
Building on these past advances and continuing the push toward higher quality image sensors for mobile devices, Samsung has developed ISOCELL a next generation of pixel technology, which is patent pending. The technology forms a physical barrier between neighbouring pixels – isolating the pixel. This isolation enables more photons to be collected from the micro-lens and absorbed into the correct pixel”s photodiode minimizing undesired electrical crosstalk between pixels and allowing expanded full well capacity (FWC).
Compared to conventional BSI pixels, the ISOCELL pixels decrease the crosstalk by approximately 30 percent which results in higher colour fidelity to reproduce the original colour with sharpness and richness, and increase the full well capacity (FWC) by 30 percent which leads to greater dynamic range.
In addition, an imager designed with ISOCELL can feature a 20 percent wider chief ray angle (CRA), reducing the height of the camera module. This makes it suitable for slim and small form factor mobile devices with challenging low z-height requirements.
As the first Samsung image sensor to adopt this new technology, the S5K4H5YB 8Megapixel imager utilizes a 1.12um ISOCELL pixel and has a 1/4inch optical format. The S5K4H5YB is currently sampling to customers with mass production scheduled for Q4 2013.
According to market research firm Techno System Research, in 2014, approximately 66 percent of smartphones will feature image sensors with 8Mp or higher resolution.