Abstract
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.
Highlights
Much attentions have been paid to complementary metal oxide semiconductor (CMOS)-based time-of-flight (TOF) range image sensors to be used for a variety of applications such as AR/VR/MR, security systems, drones, robots and autonomous vehicles [1,2,3,4]
single photon avalanche diode (SPAD)-based direct TOF sensors need relatively complicated circuits with high-speed clocking for time-stamp measurements of photons and statistical processing for removing the influence of ambient light and wide dynamic range, and, as a result, SPAD-based direct TOF sensors have a difficulty of having high spatial resolution, or large pixel number
To address the issues for next-generation applications of TOF imagers, this paper proposes a backside illuminated (BSI) silicon-on-insulator (SOI) based four-tap lock-in pixel indirect TOF imager using short-pulse modulation [17]
Summary
Much attentions have been paid to complementary metal oxide semiconductor (CMOS)-based time-of-flight (TOF) range image sensors to be used for a variety of applications such as AR/VR/MR, security systems, drones, robots and autonomous vehicles [1,2,3,4] These near-future applications require more distance in its measurement range and higher tolerance and resolution under high ambient light operation for outdoor use. SPAD-based direct TOF sensors need relatively complicated circuits with high-speed clocking for time-stamp measurements of photons and statistical processing for removing the influence of ambient light and wide dynamic range, and, as a result, SPAD-based direct TOF sensors have a difficulty of having high spatial resolution, or large pixel number Another issue of current SPAD-based imagers is low photon detection efficiency (PDE) at near-infrared (NIR).
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