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The design and fabrication of high-T/sub c/ chirp-response tapped delay line filters are discussed. The key components in this development were long delay lines with more than 10 ns of delay, impedance transformers, and backward-wave couplers. All of the typical transmission line geometries were examined, including microstrip, coplanar and stripline. Designs were developed using microwave CAD routines and superconducting niobium delay line prototypes. Tapped delay line chirp filters with up to 12 ns of total delay have been successfully fabricated in YBaCuO.

We have demonstrated soft x-ray projection lithography using radiation at wavelengths of 14 nm and 37 nm with a commercially available 20X reduction Schwarzschild camera. Line widths as small as 0.05 microns have been printed. The resolution obtained was essentially diffraction limited. Iridium coated mirrors were used with 37 nm radiation and Mo/Si multilayer coated mirrors with 14 nm radiation. A 1:1 magnification Offner Ring-field system with iridium coated mirrors has been used with 42 nm radiation. This optic has imaged line widths as small as 0.2 microns, which is close to the diffraction limit for this system. Transmission masks were used for all these experiments and the radiation was obtained from an undulator in the Vacuum Ultraviolet Synchrotron Storage Ring at Brookhaven National Laboratory.

Determining the cross-sectional doping profile of very small metal–oxide–semiconductor field effect transistors and specifically the direct measurement of their channel length is necessary for true channel engineering to be possible. Scanning capacitance microscopy (SCM) has generated unprecedented images of the cross-sectional doping profiles of very small transistors. The bias voltage dependence of these images has motivated us to investigate the SCM technique in greater detail. Using electrical simulations, we have focused on the pn junction to establish the qualitative and quantitative relationship between the bias voltage and the pn junction location. The ability to confidently interpret the images produced with SCM will allow us to improve simulation models, trouble-shoot process flow, and determine the effective channel length of semiconductor devices.

As MOSFET channel lengths are scaled to below 100 nm, the determination of the effective channel length, L/sub 0/ becomes increasingly important. We have studied cross-sectioned MOSFETs with gate lengths down to 90 nm using scanning capacitance microscopy (SCM), and show the first images of these state-of-the-art devices. Using a device simulator we have quantitatively established the relation between L/sub 0/ and the SCM response in the channel region, allowing us to determine L/sub 0/ from the SCM measurements. We have explored the ultimate resolution attainable using this technique; experimentally, using very sharp probe tips and with numerical simulations.

With the increased scaling down of MOSFET dimensions, delineation of the p-n junction becomes increasingly important. We have studied cross-sectioned 0.15 micron process MOSFETs using a newly developed technique, scanning capacitance microscopy (SCM), and report the first direct measurement of the channel length for these state-of-the-art devices. Using a device simulator we have quantitatively established the connection between the dopant profile and the SCM response while scanning across a p-n junction. This allows us to determine the position of the p-n junction from the SCM measurements.

Four-pole microstrip bandpass filters have been fabricated using both postannealed and in-situ-grown thin films of Y-Ba-Cu-O. The 4-GHz, 3% bandwidth filters exhibit, at 77 K, a passband insertion loss as low as 0.3 dB, compared with the 2.8-dB loss of similar gold metallic filters at the same temperature. These results demonstrate that complex passive microwave devices can be designed and implemented using high-temperature superconducting (HTS) material. More aggressive filter designs utilizing many more poles will result in much greater performance advantages for an HTS filter technology over a normal metal technology. Ultimately, ultrasharp-skirt filters can be produced, which would allow for more closely spaced communication channels and more efficient use of microwave communication bands than is currently possible with conventional filters.

Passive microwave devices are expected to be among the first devices made from high‐temperature superconductors to be inserted into system applications outside of a laboratory environment. The deposition and patterning of YBa2Cu3O7−x (YBCO) thin films has progressed sufficiently that a variety of high‐quality passive microwave devices can now be fabricated on LaAlO3 substrates. Demonstrated microwave devices include tapped‐delay‐line transversal filters with multigigahertz bandwidths, untapped delay lines, and narrowband (2% or less) microstrip filters. Potential system applications at operating temperatures of 77 K and below are discussed. The YBCO microwave devices described here demonstrate the potential performance advantages that superconducting thin‐film devices offer for high‐frequency, wide‐bandwidth, high‐performance analog signal processing systems.

It is now possible using scanning capacitance microscopy to directly obtain a two-dimensional profile of the doping in MOSFETs with gate lengths greater than 60 nm. We have accomplished this using highly doped, ultrasharp silicon cantilevers with a tip diameter of less than 10 nm. These tips provide images with very little voltage dependence (over a 1-2 V range), and improved resolution ( 30-50 nm resolution.

We have studied cross-sectioned n- and p-metal-oxide-semiconductor field effect transistors with gate lengths approaching 60 nm using a scanning capacitance microscope (SCM). In a homogeneous semiconductor, the SCM measures the depletion length, determining the dopant concentration. When imaging a real device there is an interaction between the probe tip and the built-in depletion of the p-n junction. With the help of a device simulator, we can understand the relation between the SCM images and the position of the p-n junction, making the SCM a quantitative tool for junction delineation and direct measurement of the electrical channel length.