Module Number: 12
Delivered by: University of Glasgow
Module Credits: 15
- Pre-residential work: 3
- Post-residential work: 7
- Examination: 10
- Professor Chris Wilkinson, University
- Professor Chris Wilkinson
- Dr Douglas Macintyre
- Dr Stephen Thoms
- Dr Mafuzar Rahman
- Dr Haiping Zhou
- Professor John Weaver
- Dr Maureen MacKenzie
- Mr Sam McFadzean
- Professor Philip John, Heriot-Watt
- Dr Rebecca Cheung, University of
Mark Holbrook, BOC Intellimetrics, Clydebank
- Dr Bob Gunn, Surface Technology Systems,
- Dr Geoff Halsall, Oxford Instruments,
- Dr Mark Dineen, Oxford Instruments,
- Mr Nick Appleyard, Trikon, Newport
- Marconi, Caswell.
- Motorola, East Kilbride
The aim of this module is to present
in depth, the science and technology of wet and dry etching as used
in the silicon industry.
On successful completion of this module
Delegates will have gained:
- knowledge of the science and chemistry
of wet etching of silicon and related materials;
- an understanding of the chemical
and physical processes responsible for the dry etching of silicon
and related materials;
- a sound working knowledge of the
role of the masking layer during etching;
- an appreciation of the limitations
of particular etching procedures;
- acquisition of the tools for analysing
etching processes and modelling improvements;
- Pre-residential sessions: assignments
- Post-residential sessions: assignments
- Examination: (supervised) 50%
Background to the Module:
Etching is a vital step in the production
of integrated circuits. The pattern, defined in a deposited layer of
photoresist using a lithographic process step, is transferred by etching
into the Silicon itself, or into a deposited or grown layer of conducting
material (metal, poly-Si, silicide for example) or insulating material
(silicon oxide, silicon nitride or a glass). The etching can be done
using wet chemicals or by dry etching in an ionic discharge; the latter
route usually being preferred.
Persons who would benefit from the
module include process engineers wishing to understand the fundamentals
of the etching procedures used within the industry, and engineers and
technologists with an interest in developing specialised etching processes.
This module will also be of interest to equipment engineers who already
have specialist practical knowledge of the systems used for etching,
as well as engineering managers seeking to widen their knowledge base.
The module includes both the theory and the practical realities of etching,
with an emphasis on plasma etching.
Delegates undertaking this module,
normally will be required to have an appropriate engineering (electronic,
electrical or mechanical) or a science (physics, chemistry, material
science or metallurgy) discipline to Honours Degree level. Experience
in the semiconductor fabrication industry will be beneficial.
Delivery & Assignments:
- Pre-residential sessions:
- directed reading from recommended
texts and from material available on a restricted access Web site.
- written exercises.
- Residential Week (35 hours contact
- Laboratory sessions/demonstrations
- Tutorials/case studies
- Post-residential sessions:
- completion of selected tutorial
questions on pattern transfer techniques and technology.
- an essay (2000 to 4000 words)
on a topic selected in consultation with the delegate
- a closed book written examination
(3 questions out of 5, 2 hours)
- Lectures 22½ hours
- Laboratory sessions 7½ hours
- Tutorials 4½ hours
|Overview of Pattern Transfer
pattern definition and patter transfer. Overview of methods.
||Isotropic and crystallographic
direction dependent etching of Silicon; etching of silicon oxide,
nitride etc.; safety and machine considerations.
|Dry Etching: introduction
and Classification into machine types: gaseous discharge considerations
ECR, ICP. Nature of plasma, ion frequency, ion density.
tuning, gas management, scrubbing, valves. Vacuum for dry etching:
pump types and uses.
|Material Removal and
||Physical and chemical
mechanisms in dry formation etching: sputtering, reactive ion etching,
role of radicals, selectivity, polymer formation.
||Choice of mask, sputter
rates, wet etch considerations. Profile.
||Examples of different
mixtures for same process critical assessment.
|Control and evaluation
||Methods of control. Evaluation
of etch depth and profile. Progress towards automatic control.
pressure, power, bias voltage on etch rate and damage. Effect of magnetic
|ICP and ECR machines
||Need for and uses of
high density plasma machines, including deep etch for MEMS.
||Nature of damage. Causes.
Methods of evaluation. Methods of reduction.
|Etching of Binaries
||Particular problems found
etching binary Compounds: Si-Ge are well as III-V's.
Four sessions with discussion and presentation
of particular machines are included; particular points will be illustrated
by providing access to the eight dry etching machines in Glasgow University.
is a suggested list of books useful for Delegates undertaking this module.
It is not recommended that you should read all the books 'cover to cover',
but rather use them to ensure a familiarity with the subject. Choose
the two or three which match your requirements most closely. Please
note that this is not a topic with a single book that covers all the
- 'Plasma Etching - An Introduction':
Manos & Flamm, Plasma Etching - An Introduction, Academic Press, 1989,
ISBN: 0124-693-709; (Chapters I & II - An
Introduction, will be refered to during the residential week)
- 'Glow Discharge Processes: Spluttering
& Plasma Etching', B. Chapman, Wiley, 1992, ISBN: 047-1078-28X;
- 'Plasma Etching: Physical Basis
& Processes', Sugawara, Oxford, 1998, ISBN: 019-856-287X;
- 'Journal of Science & Technology'
IBM 1998, (this will be handed out during the residential week foc)
- 'ULSI Technology', Chang & Sze,
McGraw-Hill, 1996, ISBN: 0-07-114105-7;
- 'VLSI Technology' Sze, McGraw-Hill,
1998, ISBN: 0-07-100347-9;
- 'Process Engineering Analysis in
Semiconductor Device Fabrication', S Middleman & A K Hichberg,
McGraw-Hill, 1993, ISBN: 007-0418-535;
- 'Silicon Micromachining', M Elwenspoek
& H Jansen, Cambridge, 1999, ISBN: 052-159-054X;
CONFERENCE & JOURNAL PAPERS:
- L G Deng, M Rahman, S K Murad, A
Boyd, C D W Wilkinson, "Can dry-etching systems be designed for low
damage ab initio?" J. Vac. Sci. Technol., B16, 3334 -3338, 1998
- S.K. Murad, S.P. Beaumont, M. Holland,
C.D.W. Wilkinson, 'Selective reactive ion etching of InGaAs and InP
over InAlAs in Si/Cl4/HBr plasmas', J. Vac. Sci. Technol . B, 13,
- S.Murad, M.Rahman, N.Johnson, S.Thoms,
S.P.Beaumont and C.D.W.Wilkinson,'Dry etching damage in III-V semiconductors'
J.Vac.Sci.Tech. B14, 3658-3662,1996
- S.E.Hicks, W.Parkes, J.A.H.Wilkinson
and C.D.W.Wilkinson, 'Reflectance modelling for in situ dry etch monitoring
of bulk SiO2 and III-V multilayer structures, 'J.Vac.Sci. Techol,
B12, 3306-3310, 1994.
- D. Coquillat, S.K. Murad, A. Ribayrol,
C.J.M. Smith, R.M. DeLaRue, C.D.W. Wilkinson, O. Briot, R.L. Aulombard,
'Nanometre scale reactive ion etching of GaN epilayers', Materials
Science Forum, Vols 264-268,1403-1406,1998
NB: Details of module content, timetable
and lecturers may be subject to change