Advanced Silicon Processing & Manufacturing Techniques

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MODULE PROFILE

Module Number: 12

Title: Etch

Delivered by: University of Glasgow

Module Credits: 15

Assessment Weighting:

  • Pre-residential work: 3
  • Post-residential work: 7
  • Examination: 10

Convenor:

  • Professor Chris Wilkinson, University of Glasgow

Lecturers/Tutors:
Internal:

  • Professor Chris Wilkinson
  • Dr Douglas Macintyre
  • Dr Stephen Thoms
  • Dr Mafuzar Rahman
  • Dr Haiping Zhou
  • Professor John Weaver
  • Dr Maureen MacKenzie
  • Mr Sam McFadzean

External:

  • Professor Philip John, Heriot-Watt University
  • Dr Rebecca Cheung, University of Edinburgh

Industrial:

  • Dr Mark Holbrook, BOC Intellimetrics, Clydebank
  • Dr Bob Gunn, Surface Technology Systems, Newport
  • Dr Geoff Halsall, Oxford Instruments, Bristol
  • Dr Mark Dineen, Oxford Instruments, Bristol
  • Mr Nick Appleyard, Trikon, Newport

Industrial Advisors:

  • Marconi, Caswell.
  • Motorola, East Kilbride

Aims:

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.

Learning Obectives:

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;

Assessment:

  • Pre-residential sessions: assignments 15%
  • Post-residential sessions: assignments 35%
  • 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.

Pre-requisite Knowledge:

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 time):
    • Lectures
    • Laboratory sessions/demonstrations
    • Tutorials/case studies
    • Exercises
  • 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)

SYLLABUS

  • Lectures 22 hours
  • Laboratory sessions 7 hours
  • Tutorials 4 hours
Hours
Topic Content
1
Overview of Pattern Transfer Relationship between pattern definition and patter transfer. Overview of methods.
1
Wet etching Isotropic and crystallographic direction dependent etching of Silicon; etching of silicon oxide, nitride etc.; safety and machine considerations.
3
Dry Etching: introduction and Classification into machine types: gaseous discharge considerations Plasma,reactive ion, ECR, ICP. Nature of plasma, ion frequency, ion density.
3
Equipment Design r.f. considerations, tuning, gas management, scrubbing, valves. Vacuum for dry etching: pump types and uses.
3
Material Removal and polymer Physical and chemical mechanisms in dry formation etching: sputtering, reactive ion etching, role of radicals, selectivity, polymer formation.
1
Masking considerations Choice of mask, sputter rates, wet etch considerations. Profile.
1
Gas mixtures Examples of different mixtures for same process critical assessment.
1
Control and evaluation Methods of control. Evaluation of etch depth and profile. Progress towards automatic control.
1
Relationships between parameters Relationships between pressure, power, bias voltage on etch rate and damage. Effect of magnetic field.
1
ICP and ECR machines Need for and uses of high density plasma machines, including deep etch for MEMS.
1
Damage Nature of damage. Causes. Methods of evaluation. Methods of reduction.
1
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.

Recommended Texts:

The following 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 course material.

  • '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, 2344-2349,1995.
  • 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

TIMETABLE

NB: Details of module content, timetable and lecturers may be subject to change

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Module 12

 

   
Time
Monday
Tuesday
Wednesday
Thursday
Friday
09.00 - 10.30

Housekeeping Details & Overview for the Week ========
Review of Pattern Transfer Ready for Etching

Introduction to Dry Etch II
Plasma Generation II
Etch Gases Examples II
Specific questions/
Discussions
10.30 - 11.00
COFFEE
COFFEE
COFFEE
COFFEE
COFFEE
11.00 - 12.30
Wet etching of Silicon
Plasma Generation (I)

Etch Gases Examples I

Masking Materials & Evaluation Etch Profiles

Deep etching for MEMS

12.30 - 14.00
LUNCH
LUNCH
LUNCH
LUNCH
LUNCH
14.00 - 15.30

Introduction to dry etching I

Vacuum & Other Machine Considerations

Evaluation of Etching

Damage in Si & III-V's

Etching of binaries/Si-Ge & GA's

15.30 - 16.00
TEA
TEA
TEA
TEA
TEA
16.00 - 18.30

In-situ measurements - I

SiO2 Etching

Silicon & Metal Etching

III-V & Metal Etching Machines

Deep Si Etching
Course Ends

       
COURSE BANQUET
Enquiries and further information from:

Mrs Sandra Peace
IGDS Programme Co-ordinator
IGDS Office
School of Electronics and Physical Sciences
University of Surrey
Guildford
Surrey
GU2 7XH UK

Tel +44 (0)1483 686 138
Fax +44 (0)1483 686 139
e-mail: s.peace@surrey.ac.uk
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