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Novel diode test structures have been manufactured to characterize long-range dopant diffusion in tungsten silicide layers. A tungsten silicide to p-type silicon contact has been characterized as a Schottky barrier rectifying contact with a silicide work function of 4.8 eV. Long-range diffusion of boron for an anneal at 900[degrees]C for 30 min has been shown to alter this contact to become ohmic. Long-range diffusion of phosphorus with a similar anneal alters the contact to become a bipolar n-p diode. Bipolar diode action is demonstrated experimentally for anneal schedules of 30 min at 900[degrees]C, indicating long-range diffusion of phosphorus (~38/[micro]m). SIMS analysis shows dopant redistribution is adversely affected by segregation to the silicide/oxide interface. The concept of conduit diffusion has been demonstrated experimentally for application in advanced bipolar transistor technology. Index Terms--Diffusion processes, diodes, doping, tungsten compounds.

The design and assimilation of a novel silicon Schottky diode for nonlinear transmission line (NLTL) applications is discussed. It is concluded that the measured CV characteristic of the Schottky diode, which is the key for the NLTL design, gives strong nonlinear capacitance variation with the reverse bias voltage where the capacitance varies from 182 fF to 47.5 fF as the bias voltage changes from 0 to -5V.

In this paper, we show that a multilayer freestanding slot array can be designed to give an insertion loss which is significantly lower than the value obtainable from a conventional dielectric backed printed frequency selective surface (FSS). This increase in filter efficiency is highlighted by comparing the performance of two structures designed to provide frequency selective beamsplitting in the quasioptical feed train of a submillimeter wave space borne radiometer. A two layer substrateless FSS providing more than 20 dB of isolation between the bands 316.5-325.5 GHz and 349.5-358.5 GHz, gives an insertion loss of 0.6 dB when the filter is orientated at 45[degrees] incidence in the TM plane, whereas the loss exhibited by a conventional printed FSS is in excess of 2 dB. A similar frequency response can be obtained in the TE plane, but here a triple screen structure is required and the conductor loss is shown to be comparable to the absorption loss of a dielectric backed FSS. Experimental devices have been fabricated using a precision micro-machining technique. Transmission measurements performed in the range 250-360 GHz are in good agreement with the simulated spectral performance of the individual periodic screens and the two multilayer freestanding FSS structures. Index Terms--frequency selective surface (FSS), mesh filters, millimeter wave, quasi-optical technology, submillimeter wave.

A surface-oriented planar Schottky diode for use as a detector diode on Si monolithic microwave integrated circuits (MMIC's) was developed. The active n-on-[n.sup.+] and contact [n.sup.+] regions were doped on the high-resistivity silicon substrate using phosphorus ion implantation. The PtSi-Si barrier was formed by metallurgical interaction between pure platinum film and silicon. The process technology developed for the Schottky-detector diode fabrication is precise, simple, and cheap, and is suitable for mass production. The typical measured cutoff frequency of a zero-biased fabricated Schottky diode is 118 GHz.

A novel low RF loss trenched coplanar waveguide (CPW) transmission-line structure fabricated using evaporated aluminum tracks on a high-resistivity (10-k[Omega] [center dot] cm) silicon (HRS) substrate is reported. By assuming that Schottky contact boundaries exist at the metal silicon substrate interface in the CPW line, the finite-element analysis method is used to determine the simulated behavior of the structure. The distributed capacitance, leakage conduction current, and dynamic shunt conductance for the line are shown to be a function of dc bias applied to the line, and also to reduce as a function of trench depth in the normal bias regime. Experimental results show: 1) the reduction of RF losses in comparison with conventional aluminum conductor CPW line structures may be as much as 0.5 dB/cm at 30 GHz; 2) by proper positive dc biasing of a CPW line on a p-type HRS substrate, a further reduction (0.2 dB/cm) in RF loss at 30 GHz can be achieved; 3) predicted trends in line leakage current, capacitance, and relative characteristics impedance are experimentally verified. The proposed waveguide structure may be utilized in a special fabrication process designed for RF/microwave applications. Index Terms - Capacitance, conductance, CPW, loss, MMIC.

The design, construction and measured performance is described of an offset parabolic reflector antenna which employs a reflectarray subreflector to tilt the focused beam from the boresight direction at 94 GHz. An analysis technique based on the method of moments (MoM) is used to design the dual-reflector antenna. Numerical simulations were employed to demonstrate that the high gain pattern of the antenna can be tilted to a predetermined angle by introducing a progressive phase shift across the aperture of the reflectarray. Experimental validation of the approach was made by constructing a 28 x 28 element patch reflectarray which was designed to deflect the beam 5° from the boresight direction in the azimuth plane. The array was printed on a 115 μm thick metal backed quartz wafer and the radiation patterns of the dual reflector antenna were measured from 92.6-95.5 GHz. The experimental results are used to validate the analysis technique by comparing the radiation patterns and the reduction in the peak gain due to beam deflection from the boresight direction. Moreover the results demonstrate that this design concept can be developed further to create an electronically scanned dual reflector antenna by using a tunable reflectarray subreflector. [ABSTRACT FROM AUTHOR]

Novel diode test structures have been manufactured to characterize long-range dopant diffusion in tungsten suicide layers. A tungsten silicide to p-type silicon contact has been characterized as a Schottky barrier rectifying contact with a suicide work function of 4.8 eV. Long-range diffusion of boron for an anneal at 900 °C for 30 mm has been shown to alter this contact to become ohmic. Long-range diffusion of phosphorus with a similar anneal alters the contact to become a bipolar n-p diode. Bipolar diode action is demonstrated experimentally for anneal schedules of 30 mm at 900 °C, indicating long-range diffusion of phosphorus (~38 nm). SIMS analysis shows dopant redistribution is adversely affected by segregation to the silicide/oxide interface. The concept of conduit diffusion has been demonstrated experimentally for application in advanced bipolar transistor technology. [ABSTRACT FROM AUTHOR]