RF noise in 0.18-/spl mu/m and 0.13-/spl mu/m MOSFETs

Studied the gate finger number and gate length dependence on minimum noise figure (NF/sub min/) in deep submicrometer MOSFETs. A lowest NF/sub min/ of 0.93 dB is measured in 0.18-/spl mu/m MOSFET at 5.8 GHz as increasing finger number to 50 fingers, but increases abnormally when above 50. The scaling gate length to 0.13 /spl mu/m shows larger NFmin than the 0.18-/spl mu/m case at the same finger number. From the analysis of a well-calibrated device model, the abnormal finger number dependence is due to the combined effect of reducing gate resistance and increasing substrate loss as increasing finger number. The scaling to 0.13-/spl mu/m MOSFET gives higher NF/sub min/ due to the higher gate resistance and a modified T-gate structure proposed to optimize the NF/sub min/ for further scaling down of the MOSFET.     

500 /spl mu/m diameter CMOS compatible avalanche photodiodes with 500 MHz bandwidth

Novel silicon-on-insulator, large area (500 /spl mu/m diameter), CMOS avalanche photodiodes for use with plastic optical fibre are presented. Patterns have been formed on the devices to reduce junction capacitance. Measurements on the patterned devices, at 650 nm and 26 V reverse bias, revealed bandwidths of >500 MHz.     

30-GHz bandwidth 1.55-/spl mu/m strain-compensated InGaAlAs-InGaAsP MQW laser

High-speed 1.55 /spl mu/m laser diodes with a 3-dB modulation bandwidths of 30 GHz were fabricated by using short-cavity mushroom structures with undoped, strain-compensated InGaAlAs-InGaAsP twenty-quantum-well active regions. The bandwidths were achieved at low bias current of 100 mA. The laser exhibited a high differential gain of 1.54/spl times/10/sup -15/ cm/sup 2/ and a small K factor of 0.135 ns. These results were achieved by using an In/sub 0.386/Ga/sub 0.465/AlAs barrier with 0.83% tensile strain to reduce the thermal emission time of holes from wells and hence the hole transport time.     

Stress-induced polymer waveguides operating at both 1.31 and 1.55 /spl mu/m wavelengths

Metal-defined polymer optical waveguides have been demonstrated for the first time. A metal strip patterned on top of a polymer slab waveguide causes a stress-induced refractive index change, providing lateral optical mode confinement within the core layer. Fabricated waveguides exhibit low propagation loss values of 1.1 dB/cm at 1.31 /spl mu/m and 1.3 dB/cm at 1.55 /spl mu/m for both TE and TM polarisations.     

1.47 /spl mu/m Tm/sup 3+/:ZBLAN fibre laser pumped at 1.064 /spl mu/m

A large core area (1257 /spl mu/m/sup 2/) Tm/sup 3+/-doped ZBLAN fibre laser operated at 1.47 /spl mu/m is demonstrated. The pump source is a Nd:YAG laser operated at 1.064 /spl mu/m. A laser output power of 1.56 W continuous wave was obtained for 5.2 W of launched pump power. The slope efficiency with respect to the launched pump power was measured to be 33%.     

Low-output-impedance 0.6 /spl mu/m CMOS sub-bandgap reference

A 0.6 mum CMOS sub-bandgap reference circuit, the output voltage of which is, unlike reported in the literature, concurrently low voltage and low output impedance, is presented. Experimental measurements verify that the proposed circuit, which produces a first-order temperature-compensated reference voltage of 890 my sources up to 5 mA of load current and rejects noise by a factor of 30.8-8.1 dB at 500 kHz- 4 MHz, neither of which feature is achieved by state-of-the-art sub-bandgap circuits.     

Air-gaps in 0.3 /spl mu/m electrical interconnections

A copper/air-gap interconnection structure using a sacrificial polymer and SiO/sub 2/ in a damascene process has been demonstrated. The air-gap occupies the entire intralevel volume with fully densified SiO/sub 2/ as the planar interlevel dielectric. The copper was deposited by physical vapor deposition and planarized by chemical-mechanical planarization. The Ta/Cu barrier/seed layer was deposited by physical vapor deposition; the bulk copper was electrochemically deposited. The resulting structure has an effective intralevel dielectric constant of 2.19.     

A 34 /spl mu/m/SUP 2/ DRAM cell fabricated with a 1 /spl mu/m single-level polycide FET technology

Dynamic RAM test arrays have been fabricated using a single-level polycide FET technology and a cell layout in which the top electrode of a given cell storage capacitor is provided by the adjacent word line. This layout achieves the same density as the conventional double-polysilicon cell, and comparable performance is obtained using a low-resistance polycide word line. Hi-C implants in the storage region provide increased capacitance, better isolation, and reduced transient noise. Design and operation considerations for the cell and arrays are described and measured results are compared to the design values. A cell area of 34 /spl mu/m/SUP 2/ is achieved using a scaled-down n-channel FET technology with a 22.5 nm gate oxide and 1 /spl mu/m minimum mask feature size.     

Robust sound localization in 0.18 /spl mu/m CMOS

This paper presents a hardware implementation of a sound localization algorithm that localizes a single sound source by using the information gathered by two separated microphones. This is achieved through estimating the time delay of arrival (TDOA) of sound at the two microphones. We have used a TDOA algorithm known as the "phase transform" to minimize the effects of reverberations and noise from the environment. Simplifications to the chosen TDOA algorithm were made in order to replace complex operations, such as the cosine function, with less expensive ones, such as iterative additions. The custom digital signal processor implementing this algorithm was designed in a 0.18-/spl mu/m CMOS process and tested successfully. The test chip is capable of localizing the direction of a sound source within 2.2/spl deg/ of accuracy, utilizing approximately 30 mW of power and 6.25 mm/sup 2/ of silicon area.     

Fiber-Optical Transmission Between 0.8 and 1.4 /spl mu/m

The present state of the art and expected development in discrete components for Fiber-optic transmission systems are reviewed. Predicted performance of fiber systems in the 0.85, 1.06, and 1.27 /spl mu/m regions is presented, and the advantages of longer wavelength operation quantified. Itisconcluded that operation near 1.27 /spl mu/m is particularly attractive for a) moderate data rate systems employing LED's and multimode fibers whose chromatic dispersion and attenuation are greatly reduced compared with 0.85 and 1.06 /spl mu/m, and b) high data rate systems employing lasers and monomode fibers. In systems employing lasers and graded index multimode fibers, the advantage of 1.27/spl mu/m versus 1.06 /spl mu/m operation is not as pronounced, although transmission distances at both of these longer wavelengths are significantly increased from those at 0.85 /spl mu/m.     

28 GHz optical injection-locked 1.55 /spl mu/m VCSELs

A record resonance frequency of 28 GHz and an intrinsic laser 3 dB bandwidth of 34 GHz is reported for a directly modulated injection-locked 1.55 /spl mu/m VCSEL. The small-signal modulation response is experimentally investigated using polarisation-maintaining components.     

A 4 /spl mu/m NMOS NAND structure PLA

A PLA of NAND structure, using a NMOS Si gate process, has been developed to minimize chip area and maintain medium fast speed. The smallest memory cell size of 7/spl times/9 /spl mu/m is achieved by using ion implantation for PLA bit programming with 4 /spl mu/m design rules. Dynamic clocking scheme and self-timing circuits which are used in this PLA are described. With PLA size at 20/spl times/20/spl times/20, transistor size of 8 /spl mu/m/4 /spl mu/m, and cell size of 7/spl times/12 /spl mu/m, an internal access time of 150 ns is achieved with an external 4 MHz clock. Measured circuit power dissipation is 20 mW under normal conditions.     

Vertical-cavity amplifying photonic switch at 1.5 /spl mu/m

The development of a fast amplifying switch operating at 1.55-/spl mu/m wavelength is of particular interest as the active element in optical communication systems. We report the first vertical-cavity amplifying photonic switch (VCAPS) at 1.55-/spl mu/m wavelength, with a 14-dB gain and 10-ps commutation time. This structure is fabricated by the epitaxial lift-off technique and is composed of a resonant periodic gain multiple quantum wells active layers sandwiched between a SiO/sub 2/-Au back mirror based on a Si substrate and a Si-SiO/sub 2/ front mirror.     

Thin-film /spl lambda//spl sim/3.7 /spl mu/m 'W' laser released from InAs substrate

A mid-infrared type-II 'W' laser fabricated by releasing the epitaxial film from its original InAs substrate is reported. The process exploits the extreme selectivity between GaSb and InAs when etched by hydrochloric acid. The detached film is coated with an Si/sub 3/N/sub 4/ optical cladding layer, grafted to a foreign GaAs substrate, and cleaved into laser bars. For epitaxial-side-up mounting, the device operates to 70 K, with a low threshold (/spl sime/150 W/cm/sup 2/) when pumped with the maximum available CW power of 320 mW from a 980 nm laser diode.     

Wideband quantum-dash-in-well superluminescent diode at 1.6 /spl mu/m

We demonstrate broadband superluminescent diode at /spl sim/1.6-/spl mu/m peak emission wavelength using InAs-InAlGaAs quantum-dash-in-well structure on InP substrate. The fabricated device exhibits the close-to-Gaussian emission with a bandwidth of up to 140 nm. The device produces a low spectrum ripple of 0.3dB and an integrated power of 1.7 mW with the corresponding bandwith of 110 nm measured at 20 /spl deg/C under 8 kA/cm/sup 2/.     

A 1-/spl mu/m Bipolar VLSI Technology

A 1-/spl mu/m VLSI process technology has been developed for the fabrication of bipolar circuits. The process employs electron-beam slicing writing, plasma processing, ion implantation, and low-temperature oxidation/annealing to fabricate bipolar device structures with a minimum feature size of 0.9 /spl mu/m. Both nonisolated I/sup 2/L and isolated Schottky transistor logic (STL) devices and circuits have been fabricated with this process technology. The primary demonstration vehicle is a seated LSI, I/sup 2/L, 4-bit processor chip (SBP0400) with a minimum feature size of 1 /spl mu/m. Scaled SPB0400's have been fabricated that operate at clock speeds 3X higher than their full-size counterparts at 50-mA chip current. Average propagation delay has been measured as a function of minimum feature size for both I/sup 2/L and STL device designs. Power-delay products of 14 fJ for I/sup 2/L and 30 fJ for STL have been measured.     

A surface-normal coupled-quantum-well modulator at 1.55 /spl mu/m

We demonstrate a surface-normal coupled-quantum-well InGaAs-InAlAs electroabsorption modulator that provides optical modulation with a contrast ratio in excess of 1.5 at only 6 V. The device operates at 1.55 /spl mu/m and is based on a novel strain-balanced layer structure. The operating voltage is about two times lower than that of a conventional square quantum-well modulator that achieves a comparable contrast ratio.     

Antimonide semiconductor saturable absorber for 1.5 /spl mu/m

Self-starting continuous-wave passive modelocking of an Er:Yb:glass laser at 1535 nm is demonstrated with the first antimonide semiconductor saturable absorber mirror (SESAM). The Er:Yb:glass laser produces 20 ps pulses at 61 MHz. This laser was used to characterise the nonlinear optical parameters of the metal organic vapour phase epitaxy grown SESAM.