Dark current refers to leakage currents in photosensors attributable to high temperatures or lengthy exposures. Dark currents result in photosensor noise, degrading image quality in CMOS sensors. Reducing dark currents is critical for maintaining image quality.

Drawing on its vast material analysis technologies, Canon reexamined the structural aspects of silicon substrates, discovering that crystal defects in silicon substrates can influence dark currents. Through manufacturing process innovations, Canon developed a technology to eliminate crystal defects from the surface of a silicon substrate, where CMOS sensor operations occur, isolating these defects in the deep region of the substrate where they cannot affect sensor performance. This technology made possible the mass production of high-performance CMOS sensors with minimal dark current.

Cross-Sectional Photo of Silicon Substrate