Monolithic Integration beyond 26.5 GHz


MONOFAST - 5052

Keywords MMICs, III-V materials


Start Date: 01-JAN-90 / Duration: 34 months

[ contact / participants ]


Objectives and Approach

The purpose of MONOFAST was to advance the state of the art in the design and fabrication of Monolithic Microwave Integrated Circuits (MMICs) towards higher operating frequencies.

The technologies and components needed to obtain high performance and worthwhile yields from monolithic circuits working at the frequencies proposed lie at or beyond the present state of the art for two reasons. Firstly, the fabrication tolerances needed to contain device performance spreads within acceptable limits are severe, and are unattainable or exceptionally difficult to achieve using conventional integration processes. Secondly, circuit architectures must change: in particular, it is desirable to design around coplanar waveguide interconnections to minimise parasitic inductances and to allow dimensional flexibility whilst preserving characteristic impedance. The aim of the MONOFAST project was to develop a yield-driven processing technology to enable the design and construction of low-noise amplifiers operating at 44 GHz. Both active and passive components are critical for the operation of these types of millimetre-wave circuits, which were based on coplanar waveguide (CPW) construction.

As little was known about the design of CPW circuits, part of the work-programme was concerned with the development of design methodologies for this interconnect technology. The active devices were choosen to be T-gate MESFETs fabricated on material grown by MBE, although the technologies developed were intended to be readily applicable to HEMTs. High-resolution electron-beam and ion-beam lithographic methods were planned to be employed for pattern delineation, and dry etching was to be developed for forming recesses and to meet other etching needs. Most of the planned results have been achieved.

Progress and Results

Most of the planned results have been achieved. Process and component designs have been refined using reverse device engineering to converge towards a process technology capable of giving an acceptable yield in any future exploitation of the research. FETs with 0.2 micron T gates exhibiting performances close to the state of the art at 44 GHz have been realised. The experimental and theoretical results obtained, in particular concerning the coplanar passive waveguide elements, are very interesting not only for the partners in the consortium but also for other industrial companies.


CONTACT POINT

Prof Steven Beaumont
UNIVERSITY OF GLASGOW
The University
UK - GLASGOW G12 8QQ
tel: + 44/ 41-3305380
fax: + 44/ 41-3304907
telex: 777070 UNI GLA G

Participants

UNIVERSITY OF GLASGOW - UK - C
ALCATEL ESPACE - F - P
GAAS CODE LTD - UK - P
UNIVERSITY OF CAMBRIDGE - UK - P
NATIONAL MICROELECTRONICS
RESEARCH CENTRE - IRL - P
FARRAN TECHNOLOGY LTD - IRL - P


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MONOFAST - 5052, December 1993


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html version of synopsis by Nick Cook