Optimizing a CMOS Integrated Photon Counting Light-Field Sensor Based on Metal-VIA Multicomponent Grating

Abstract

A Complementary metal-oxide--semiconduc- tor (CMOS) angle-sensitive, single-photon avalanche diode (ASPAD) sensor can extract plenoptic information from a single photon to enable lens-less optics based on computational methods. However, ASPAD sensors have been constrained by foundry metal stack designs, limiting their modulation gain. In this article, we propose a design methodology that significantly enhances the modulation gain by using vertical interconnect access (VIA) layers as an additional optical grating element. The metal-VIA grating structure reduces the pitch-wavelength-layer trade-off and extends the modulation range. Through measurement, we demonstrated modulation gain increase of up to 16.13% across various angle sensitivities. The design was manufactured using a standard CMOS 4M1P 110 nm process.