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Radiation effects in 3D integrated SOI SRAM circuits

Summary

Radiation effects are presented for the first time for vertically integrated 3 x 64 -kb SOI SRAM circuits fabricated using the 3D process developed at MIT Lincoln Laboratory. Three fully-fabricated 2D circuit wafers are stacked using standard CMOS fabrication techniques including thin-film planarization, layer alignment and oxide bonding. Micron-scale dense 3D vias are fabricated to interconnect circuits between tiers. Ionizing dose and single event effects are discussed for proton irradiation with energies between 4.8 and 500 MeV. Results are compared with 14-MeV neutron irradiation. Single event upset cross section, tier-to-tier and angular effects are discussed. The interaction of 500-MeV protons with tungsten interconnects is investigated usingMonte-Carlo simulations. Results show no tier-to-tier effects and comparable radiation effects on 2D and 3D SRAMs. 3DIC technology should be a good candidate for fabricating circuits for space applications.
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Summary

Radiation effects are presented for the first time for vertically integrated 3 x 64 -kb SOI SRAM circuits fabricated using the 3D process developed at MIT Lincoln Laboratory. Three fully-fabricated 2D circuit wafers are stacked using standard CMOS fabrication techniques including thin-film planarization, layer alignment and oxide bonding. Micron-scale dense...

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Wafer-scale 3D integration of InGaAs image sensors with Si readout circuits

Summary

In this work, we modified our wafer-scale 3D integration technique, originally developed for Si, to hybridize InP-based image sensor arrays with Si readout circuits. InGaAs image arrays based on the InGaAs layer grown on InP substrates were fabricated in the same processing line as silicon-on-insulator (SOI) readout circuits. The finished 150-mm-diameter InP wafer was then directly bonded to the SOI wafer and interconnected to the Si readout circuits by 3D vias. A 1024 x 1024 diode array with 8-um pixel size is demonstrated. This work shows the wafer-scale 3D integration of a compound semiconductor with Si.
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Summary

In this work, we modified our wafer-scale 3D integration technique, originally developed for Si, to hybridize InP-based image sensor arrays with Si readout circuits. InGaAs image arrays based on the InGaAs layer grown on InP substrates were fabricated in the same processing line as silicon-on-insulator (SOI) readout circuits. The finished...

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A 4-side tileable back illuminated 3D-integrated Mpixel CMOS image sensor

Summary

The dominant trend with conventional image sensors is toward scaled-down pixel sizes to increase spatial resolution and decrease chip size and cost. While highly capable chips, these monolithic image sensors devote substantial perimeter area to signal acquisition and control circuitry and trade off pixel complexity for fill factor. For applications such as wide-area persistent surveillance, reconnaissance, and astronomical sky surveys it is desirable to have simultaneous near-real-time imagery with fast, wide field-of-view coverage. Since the fabrication of a complex large-format sensor on a single piece of silicon is cost and yield-prohibitive and is limited to the wafer size, for these applications many smaller-sized image sensors are tiled together to realize very large arrays. Ideally the tiled image sensor has no missing pixels and the pixel pitch is continuous across the seam to minimize loss of information content. CCD-based imagers have been favored for these large mosaic arrays because of their low noise and high sensitivity, but CMOS-based image sensors bring architectural benefits, including electronic shutters, enhanced radiation tolerance, and higher data-rate digital outputs that are more easily scalable to larger arrays. In this report the first back-illuminated, 1 Mpixel, 3D-integrated CMOS image sensor with 8 mum-pitch 3D via connections. The chip employs a conventional pixel layout and requires 500 mum of perimeter silicon to house the support circuitry and protect the array from saw damage. In this paper we present a back-illuminated 1 Mpixel CMOS image sensor tile that includes a 64-channel vertically integrated ADC chip stack, and requires only a few pixels of silicon perimeter to the pixel array. The tile and system connector design support 4-side abuttability and fast burst data rates.
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Summary

The dominant trend with conventional image sensors is toward scaled-down pixel sizes to increase spatial resolution and decrease chip size and cost. While highly capable chips, these monolithic image sensors devote substantial perimeter area to signal acquisition and control circuitry and trade off pixel complexity for fill factor. For applications...

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A 64 x 64-pixel CMOS test chip for the development of large-format ultra-high-speed snapshot imagers

Summary

A 64 x 64-pixel test circuit was designed and fabricated in 0.18- m CMOS technology for investigating high-speed imaging with large-format imagers. Several features are integrated into the circuit architecture to achieve fast exposure times with low-skew and jitter for simultaneous pixel snapshots. These features include an H-tree clock distribution with local and global repeaters, single-edge trigger propagation, local exposure control, and current-steering sampling circuits. To evaluate the circuit performance, test structures are periodically located throughout the 64 x 64-pixel device. Measured devices have exposure times that can be varied between 75 ps to 305 ps with skew times for all pixels less than +-3 ps and jitter that is less than +-1.2 ps rms. Other performance characteristics are a readout noise of approximately 115 e- rms and an upper dynamic range of 310,000 e-.
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Summary

A 64 x 64-pixel test circuit was designed and fabricated in 0.18- m CMOS technology for investigating high-speed imaging with large-format imagers. Several features are integrated into the circuit architecture to achieve fast exposure times with low-skew and jitter for simultaneous pixel snapshots. These features include an H-tree clock distribution...

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Laser radar imager based on 3D integration of Geiger-mode avalanche photodiodes with two SOI timing circuit layers

Summary

We have developed focal-plane arrays and laser-radar (ladar) imaging systems based on Geiger-mode avalanche photodiodes (APDs) integrated with high-speed all-digital CMOS timing circuits. A Geiger-mode APD produces a digital pulse upon detection of a single photon. This pulse is used to stop a fast digital counter in the pixel circuit, thereby measuring photon arrival time. This "photon-to-digital conversion" yields quantum-limited sensitivity and noiseless readout, enabling high-performance ladar systems. Previously reported focal planes, based on bump bonding or epoxy bonding the APDs to foundry chips, had coarse (100um) pixel spacing and 0.5ns timing quantization.
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Summary

We have developed focal-plane arrays and laser-radar (ladar) imaging systems based on Geiger-mode avalanche photodiodes (APDs) integrated with high-speed all-digital CMOS timing circuits. A Geiger-mode APD produces a digital pulse upon detection of a single photon. This pulse is used to stop a fast digital counter in the pixel circuit...

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Megapixel CMOS image sensor fabricated in three-dimensional integrated circuit technology

Summary

In this paper a 3D integrated 1024x1024, 8um pixel visible image sensor fabricated with oxide-to-oxide wafer bonding and 2-um square 3-D-vias in every pixel is presented. The 150mm wafer technology integrates a low-leakage, deep-depletion, 100% fill factor photodiode layer to a 3.3-V, 0.35-um gate length fully depleted (FD) SOI CMOS readout circuit layer.
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Summary

In this paper a 3D integrated 1024x1024, 8um pixel visible image sensor fabricated with oxide-to-oxide wafer bonding and 2-um square 3-D-vias in every pixel is presented. The 150mm wafer technology integrates a low-leakage, deep-depletion, 100% fill factor photodiode layer to a 3.3-V, 0.35-um gate length fully depleted (FD) SOI CMOS...

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