Of particular note is a highlighted paper from a team led by Micron Technology (Boise, ID), describing the first monolithic silicon-photonics-on-bulk-CMOS process flow to connect distant distributed memory devices (Paper T21.1, ¡°Integration of Silicon Photonics in Bulk CMOS,¡± R. Meade et al., Micron, MIT, U. of Colorado, and UC Berkeley).
The Micron device includes deep-trench isolation, polysilicon waveguides, grating couplers, filters, modulators, and detectors. Fully functional on-chip CMOS enables transmit/receive operation while minimizing interconnect parasitics. With the addition of an external 1280 nm light source, a fully functional optical link (5 Gbit/s with 2.8 pJ/bit), capable of WDM (wavelength division multiplexing), has been demonstrated. In addition to the polysilicon resonant detector used in the link, a monolithically integrated silicon-germanium (SiGe)-based photodetector using selective epitaxial growth was also developed.
From the abstract: “Other research groups have published on SOI devices or ‘stand-alone’ silicon photonics (i.e. not monolithically integrated). This paper is different in that, for the first time, a working optical link has been demonstrated on an economically feasible (specifically for memory) CMOS platform. Today, 3D integration is a major industry focus in part due to the power and performance requirements of chip-to- chip I/O. While 3D integration is important, this research shows a clear alternative path that has significant benefits.”
The result is a monolithically integrated optical chip-to-chip link that transmits 5 Gbit/s over distances up to 5 m long (via fiber link).
Other photonics-related presentations
A group from National University of Singapore and Nanyang Technological University will present “Germanium-Tin on Silicon Avalanche Photodiode for Short-Wave Infrared Imaging,” in which a monolithic, CMOS-compatible germanium-tin on silicon (Ge1-xSnx/Si) avalanche photodiode (APD) for short-wave infrared (SWIR) imaging is reported that has a lower thermal sensitivity than conventional III-V-based aAPDs.
Researchers from Taiwan Semiconductor Manufacturing Company will present “Advanced 1.1 ¦Ìm Pixel CMOS Image Sensor with 3D Stacked Architecture,” in which they describe their 1.1-¦Ìm-pixel backside-illuminated CMOS image sensor with a 3D stacked architecture. The carrier wafer in conventional BSI is replaced by an ASIC wafer, which simplifies fabrication and improves dark performance.
A team from MIT and the University of Colorado, Boulder (many members of whom also worked on the Micron Technology device) will present “A Monolithically-Integrated Optical Transmitter and Receiver in a Zero-Change 45 nm SOI Process.” Here, according to the abstract, “an optical transmitter and receiver with monolithically-integrated photonic devices and circuits are demonstrated together for the first time in a commercial 45 nm SOI [silicon-on-insulator] process, without any process changes. The transmitter features an interleaved-junction carrier-depletion ring modulator and operates at 3.5 Gbit/s with an 8 dB extinction ratio and combined circuit and device energy cost of 70 fJ/bit. The optical receiver connects to an integrated SiGe detector designed for 1180 nm wavelength and performs at 2.5 Gbit/s with 15 ¦ÌA sensitivity and energy cost of 220 fJ/bit.”.
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