The Silicon-Based XOI Wafer: The Most General Electronics-Photonics Platform for Computing, Sensing, and Communications

Abstract

This paper proposes that the 300-mm-diameter silicon wafer coated with a thin insulator layer, which becomes a buried layer, is the most general and most capable platform for high-volume foundry-manufactured, waveguided, photonic integrated circuits (PICs) and for the on-wafer electronics that control and signal-process the photonics. We call this “on insulator” platform an electronic- photonic (or optoelectronic) integrated-circuit wafer. For a few potential applications like “general intelligence” (Shainline et al., 2021), entire wafers would be deployed. However, in almost every case, the wafer will be diced into hundreds of electronic-photonic chips (chips are the real aim of wafer creation). Those chips would be commercial products or custom-made, application-specific PICs. The goal of this paper is to present a detailed vision of the ultimate electronic- photonic wafers that: (1) serve a vast range of applications, (2) operate at any wavelength within the ultraviolet, visible, near-infrared and middle infrared, (3) provide low-loss, well-confined optical waveguiding across the wafer, (4) utilize an optimized or application-specific combination of photonic materials including semiconductors, insulators, ferroelectrics, poled polymers (Xu et al., 2022), phase-change materials (PCMs) (Wuttig et al., 2017), plasmonics (Moor et al., 2021), (Amin et al., 2021), and 2D materials such as graphene (Liu et al., 2020), (5) offer one-or-more practical electro-optical modulation-and-switching mechanisms that are discussed below, (6) offer on-wafer laser diodes, wavelength-multiplexed comb sources, LEDs, optical amplifiers, and photodetectors, (7) provide a full range of CMOS-or-“other” control electronics as well as electronic memories and data converters (analog-to-digital and digital-to-analog), and (8) are manufacturable in volume by proven techniques such as wafer bonding, smart cut, and hetero-epitaxy– or are made by emerging methods. The insulator mentioned above could be silicon dioxide (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) or alumina (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ), or silicon nitride (Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> or SiN). SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is generally preferred, but the Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and the SiN offer better mid- infrared transparency than the oxide.