Rashaunda Henderson

Integration of thin film MIM capacitors and resistors into copper metallization based RF-CMOS and Bi-CMOS technologies

High precision metal-insulator-metal capacitors with a capacitance density of 1.6 fF/um/sup 2/ and metal thin film resistors of 50 ohm/sq. sheet resistance and a negative temperature coefficient of resistivity smaller than 100 ppm//spl deg/C have been integrated in a dual-inlaid Cu-based backend for mixed-signal applications. These devices deliver reduced parasitics, better linearity, lower temperature coefficients, lower noise, and better matching as compared to current silicon based devices.

Silicon-based micromachined packages for high-frequency applications

A novel low-cost packaging approach is presented in this paper, which is appropriate for high-frequency electronic circuits in discrete, as well as integrated, configurations. This approach is based on silicon micromachining and can effectively provide on-wafer and discrete packaging for high-quality high-precision miniature components. The required fabrication techniques are compatible with standard integrated-circuit processing and, for this reason, are low in fabrication costs. As an example, this paper presents the development of a Ka-band package that can shield and electromagnetically isolate monolithic-microwave integrated-circuit components, such as a phase shifter. The performance of this package is compared to that of a ceramic one and demonstrates excellent electrical response in addition to high design versatility.

Three-dimensional high-frequency distribution networks. I. Optimization of CPW discontinuities

This paper describes a systematic study of coplanar waveguide discontinuities that are requisite components of high-frequency distribution networks. The specific geometries addressed are air bridges, right-angle bends, tee junctions, and Wilkinson dividers. Relative to typical monolithic-microwave integrated-circuit designs, the components studied herein are electrically large in order to minimize signal attenuation. The large size leads to pronounced parasitic effects, and the emphasis of this study was to optimize the electrical performance using simple compensation techniques. The optimization methods are developed using full-wave simulation and equivalent-circuit modeling, and are verified experimentally up to 60 GHz. Part II of this paper describes the implementation and packaging of the components to realize a three-dimensional W-band distribution network.

A reduced-size silicon micromachined high-Q resonator at 5.7 GHz

This paper depicts the progress toward a novel high-quality-factor miniaturized resonator operating in the 5.6-5.8-GHz range. The design of the resonator is based on a micromachined cavity loaded with a high dielectric-constant material. Energy is coupled into the cavity from input and output microstrip lines via slots. Quality factors up to 640 are demonstrated on silicon planar structures with a volume of 177 mm/sup 3/. Further size reduction yields a volume of 24.5 mm/sup 3/ and quality factors ranging from 152 to 197, while keeping the resonator integration ability. Bonding techniques and the dielectric loss of the loading material are proven to be the limiting factors in achieving higher quality factors.

Three-dimensional high-frequency distribution networks. II. Packaging and integration

This paper describes the implementation and packaging of the components, described in Part I of this paper, to realize a three-dimensional W-band distribution network.

Liquid metal actuation-based reversible frequency tunable monopole antenna

We report the fabrication and characterization of a reversible resonant frequency tunable antenna based on liquid metal actuation. The antenna is composed of a coplanar waveguide fed monopole stub printed on a copper-clad substrate, and a tunnel-shaped microfluidic channel linked to the printed metal. The gallium-based liquid metal can be injected and withdrawn from the channel in response to an applied air pressure. The gallium-based liquid metal is treated with hydrochloric acid to eliminate the oxide layer, and associated wetting/sticking problems, that arise from exposure to an ambient air environment. Elimination of the oxide layer allows for reliable actuation and repeatable and reversible tuning. By controlling the liquid metal slug on-demand with air pressure, the liquid metal can be readily controllable to connect/disconnect to the monopole antenna so that the physical length of the antenna reversibly tunes. The corresponding reversible resonant frequency changes from 4.9 GHz to 1.1 GHz. The antenna properties based on the liquid metal actuation were characterized by measuring the reflection coefficient and agreed well with simulation results. Additionally, the corresponding time-lapse images of controlling liquid metal in the channel were studied.

Optimization of MM-wave distribution networks using silicon-based CPW

This paper describes work relating to the optimization of silicon-based, coplanar waveguide (CPW) air-bridge and bend discontinuities. Experimental results shown here verify that the return loss is improved by introducing a step-compensation into the CPW center conductor. The technique is demonstrated in the design of an asymmetric coplanar-strip Wilkinson power divider at 45 GHz.

Advanced monolithic packaging concepts for high performance circuits and antennas

Unwanted electromagnetic coupling between neighboring elements is a common problem in high frequency planar circuits. This paper reports on the elimination of crosstalk in planar circuits using conformal micromachined packaging. In the 5 to 30 GHz range, a back-to-back right-angle bend in microstrip has cross-coupling as high as -20 dB. The use of monolithic packaging concepts reduces this coupling by as much as 20-30 dB down to the noise level of the measurement system.

Patch Antenna Array for the Generation of Millimeter-Wave Hermite–Gaussian Beams

This letter introduces a method of using patch antennas to generate millimeter-wave Hermite-Gaussian (HG) beams at E-band. An HG11 beam is formed using four inset-fed microstrip patch elements arranged with a microstrip corporate feeding network. The designed antennas are fabricated on a high-performance FR4 circuit board with a relative permittivity of 3.75 and a loss tangent of 0.018. The overall size of the antenna array is 8 × 8 × 0.125 mm3. A full-wave electromagnetic simulator, HFSS, is used to design the array. Radiation pattern measurements were taken on an NSI 700S-360 spherical near-field system at 73 GHz together with an Agilent vector network analyzer. The simulations and measurements are in good agreement.

Tantalum nitride thin film resistors for integration into copper metallization based RF-CMOS and BiCMOS technology platforms

Metal thin film resistors have been integrated into a damascene-copper multilayer metallization system for mixed-signal BiCMOS technology platforms. The thin film process can be adjusted to achieve resistors with very low temperature coefficients, high linearity, low noise, and improved matching as compared to resistors based on implanted silicon or polysilicon processing. In addition, improvement in terms of good RF performance was observed.