18-815-1995
18-815
Integrated Circuit Fabrication Processes
Note: This is the 1995 syllabus, to be revised soon
Instructor:
Prof. D.W. Greve HH B204 (X3707)
Text:Semiconductor
Integrated Circuit Processing
Technology, W.R. Runyan and K.E. Bean, (Addison Wesley,
1990).
Other
Reading:
Textbooks on Processing
Silicon
Processing for the VLSI Era- Volume I Process Technology,
(Lattice Press, 1986), S. Wolf and R.N. Tauber
(very comprehensive,
lots of practical information and photos; not easy to read and mediocre
production values)
(see also volume 2 on process integration)
Microelectronic
Processing, (McGraw Hill 1987), W.S. Ruska
(more of
an undergraduate text; readable
but less comprehensive)
VLSI Technology, (McGraw Hill,
1983), S.M. Sze, editor
(collection of articles by various authors; standard
book but not well integrated)
Electronic Materials Science and
Technology, (Academic Press, 1989), S.P. Murarka and M.C. Peckerar
(spotty
and not a favorite of mine; good on lithography and beam processing)
VLSI
Fabrication Principles, Silicon and Gallium Arsenide,
(J. Wiley and Sons, 1983)
S.K. Ghandi
(second edition of classic text; probably best of above on
GaAs, which is after all not the subject of this course)
Process Engineering
Analysis in Semiconductor Device Fabrication, (McGraw- Hill,
1993), S. Middleman, A.K. Hochberg
(from a chemical engineering viewpoint;
strong on process modeling)
Thin- Film Deposition, (McGraw-
Hill, 1995), D.L. Smith
(new book on thin films only; looks quite
promising)
Technology
CAD: Computer Simulation of IC Processes and Devices, (Kluwer Academic
Press, 1993), R.W. Dutton and Z. Yu
(for those interested in simulation
tools)
Popular magazines (with advertising and pictures in color)
Semiconductor
International
Solid State
Technology
Primary Journals
Journal
of Applied Physics
Applied Physics Letters
Journal
of the Electrochemical Society
Journal
of Electronic Materials
Jounal of
Vacuum Science and Technology, parts A and B
Course
Goals
1. Develop an understanding of the fundamental physics,
chemistry, and materials science behind microelectronic processing with an emphasis
on silicon technology.
2. Gain an appreciation of practical aspects
of semiconductor process steps.
3. Develop the ability to do first-
pass calculations using simple
models and the insight necessary to distinguish plausible results from implausible
ones.
4. Obtain an appreciation of important issues in process integration,
semiconductor manufacturing, process development, and process control.
About this course:
This course
is concerned with the fabrication technology of silicon integrated circuits
and variants thereof. I will emphasize recent developments in the understanding
of various process steps,
with substantial emphasis on epitaxy and chemical vapor deposition. Nevertheless,
the course will include (at the beginning) a descriptive outline of a modern
semiconductor process and all important process steps will then be discussed
with varying degrees of detail, including photolithography, etching, plasma deposition,
metal deposition, diffusion, CVD/ epitaxy, and ion implantation. Time
permitting, I will also outline techniques of modern process control and the construction
of experiments (response
surface and factorial techniques).
Comparatively little will be said
about simulation, which is after all just a matter of details once the basic
physics and chemistry are understood.
Who
should take this course:
Graduate students
with an interest in electronic materials and/ or semiconductor processing. The
course will be accessible to graduate students in chemical engineering, materials
science, and physics. A
basic acquaintance with semiconductor devices is assumed (although device physics
is not a part of this course).
The course also is suitable for undergraduate
students with a strong preparation in semiconductor devices, especially
those in the Electronic Materials option. Undergraduates should, however, meet
with me before registering for the course.
Relation
among the text, lecture, homework, and exam
The
text contains discussions
of process fundamentals in addition to a great deal of practical and
descriptive material. The lectures will emphasize the process fundamentals with
descriptive material will be presented only as required. You are nevertheless
responsible for reading and absorbing the descriptive part of the text. Mathematics,
chemistry, physics, and materials science presented in lecture may or
may not follow the text. Homework problems will draw primarily on the development
in lecture and you may expect
the same for the exam.
Approximate Outline:
1.
The concept of the integrated circuit; why silicon still wins; properties
of silicon; overview of various processing steps and how they fit together;
complete IC process(es).
2. Thermal oxidation: glasses and properties
of silicon dioxide; the Deal- Grove model and calculation of oxide thickness;
effects of temperature, orientation, pressure, water vapor, and doping; equipment
for oxidation.
3.
Thin films (survey): sputtering; particular plasma and thermal CVD processes;
the plasma; physics of sputtering and various equipment configurations.
4.
Epitaxy: what it is and why we want it; hetero- and homo- epitaxy;
equilibrium gas phase chemistry and what it tells us; gas phase transport limits;
surface reaction kinetics; epitaxial growth systems; a particular low-
temperature epitaxial growth process: equipment; surface cleaning; transport;
growth rate modeling; dopant
incorporation; relation to LPCVD polysilicon growth.
5. Lithography:
process outline; summary of photoresist chemistry; photoprinters: contact,
proximity, projection, stepping, e- beam, X- ray; masks: conventional and
phase- shifting; substrate effects; the astonishing and continuing dominance
of optical lithography.
6. Etching: wet etching: typical etchants and
selectivity; dry etching: isotropic and anisotropic; equipment and etchant
gases; systematic experiments
for process development; advanced process control: wafer state and process state
sensors; the challenges of real- time feedback control.
7. Diffusion:
Diffusion mechanisms; the available dopants; modeling concentration- dependent
diffusion; second- order effects; the diffusion equation and a few useful
solutions; diffusion equipment and sources; measurement of diffusion profiles.
8. Ion implantation: implanted profiles; damage and amorphization;
annealing and residual defects;
the ion implanter.
9. Back- end processing: ohmic contact processes;
Schottky barriers; multilevel metallization approaches.
Course
Assignments
It is anticipated that homework assignments
will be assigned from time to time. A few of these may require some access
to a computer for numerical calculations although simulation as such is not
the topic of this course. These will be graded on a pass/ fail basis with one
opportunity granted to correct
your solution if seriously wrong (albeit with an adverse impact on your grade).
It is expected that all students will complete essentially all assignments correctly
in a timely manner. One test is anticipated (possibly to coincide with
my conference travel) and a final paper on a topic related to semiconductor
processing and chosen by mutual consultation. The single test may or may not occur
prior to the time that midterm grades are due.