Microwave plasma-enhanced chemical vapor deposition of diamond films on silicon carbide and tungsten carbide (with 6% cobalt) surfaces using fluorocarbon gases has been demonstrated. No diamond powder pretreatment is necessary to grow these films with a (100) faceted surface morphology. The diamond films are characterized by scanning electron microscopy and Raman spectroscopy. The proposed nucleation and growth mechanism involves etching of the noncarbon component of the carbide by atomic fluorine to expose surface carbon atoms and diamond nucleation and growth on these exposed carbon atoms. Hydrogen is necessary in the growth process to limit the rapid etching of the carbide substrates by corrosive fluorine atoms.

Diamond growth on carbide surfaces using a selective etching technique

A simple photodetector has been developed to monitor plasma etching of polysilicon, pyrolytic silicon nitride and reactive plasma deposited silicon nitride.

Optical detector to monitor plasma etching

The ionisation alpha /p, electron attachment eta /p and effective ionisation alpha /p (=( alpha /p)-( eta /p)) coefficients were measured by the steady-state Townsend method for 41<or approximately=E/p<or approximately=206 V cm-1 Torr-1, where p is the gas pressure reduced to 20 degrees C. The results show that the values of alpha /p, eta /p and alpha /p are in good agreement with those of Bozin and Goodyear (1968) for E/p<or approximately=90 V cm-1 Torr-1. For larger E/p, which the present work is the first to report, the value of these parameters is found to connect, and vary, smoothly with that at lower E/p. The limiting E/p at which alpha /p= eta /p is determined to be 46.5 V cm-1 Torr-1. The value of the total secondary coefficient is measured for a limited range of E/p=120-206 V cm-1 Torr-1 and is found to assume a value of about 1*10-5 almost independent of E/p.

https://iopscience.iop.org/article/10.1088/0022-3727/16/6/007/pdf

The ionisation and attachment coefficients in carbon tetrafluoride

Pattern transfer by deep anisotropic etch is a well-established technique for fabrication of nanoscale devices and structures. For this technique to be effective, the resist material plays a key role and must have a high resolution, reasonable sensitivity, and high etch selectivity against the conventional silicon substrate or underlayer film. In this work, the lithographic performance of two high etch resistance materials was evaluated: ZEP520A (Nippon Zeon Co.) and mr-PosEBR (micro resist technology GmbH). Both materials are positive tone, polymer-based, and nonchemically amplified resists. Two exposure techniques were used: electron beam lithography (EBL) and extreme ultraviolet (EUV) lithography. These resists were originally designed for EBL patterning, where high quality patterning at sub-100 nm resolution was previously demonstrated. In the scope of this work, the authors also aim to validate their extendibility to EUV for high resolution and large area patterning. For this purpose, the same EBL pr...

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Lithographic performance of ZEP520A and mr-PosEBR resists exposed by electron beam and extreme ultraviolet lithography

In the present paper variability analysis of hyperabrupt epitaxial Schottky barrier voltage variable capacitors has been carried out. In particular, it is shown how each electrical parameter of a VVC (viz. cutoff frequency, capacitance ratio, and breakdown voltage) depends on the various physical parameters of the diffused device (viz. total no. of predeposited impurity atoms of the retrograde profile, the drive-in product D 1 t 1 , background doping, and epitaxial thickness). It is concluded that each electrical parameter has a widely different dependence on the various physical parameters and that for each specific application there are certain key physical parameters which need be tracked more closely during fabrication of the device than others. An optimum design criterion is given which shows that during an actual fabrication of such a device, if the predeposit cycle (for the retrograded hyperabrupt profile) departs from its dc (design centre) value then the later drive-in cycle should also be suitably changed from its dc value to obtain a minimum deviation of a given electrical parameter from its dc value.

Variability study and design considerations of hyperabrupt junction voltage variable capacitors

An analysis of the breakdown and capacitance properties of punch-through hyperabrupt epitaxial Schottky barrier diodes has been carried out. Results are given for the dependence of breakdown voltage of such a device on surface concentration and epitaxial layer thickness. Design curves are given for epitaxial hyperabrupt schottky varactor diodes. The design procedure yields an optimal impurity profile in which just-punch-through occurs at the highest voltage of operation. This gives a maximum dynamic range of operation still keeping the series resistance to a minimum. A corrected boundary condition to determine the profile constants associated with an n/n+ (high/low) junction is also given.

Rajendra Kumar

Papers

Variability study and design considerations of hyperabrupt junction voltage variable capacitors

Breakdown and capacitance properties of hyperabrupt epitaxial Schottky barrier diodes