Spring, 1985
Rev 1: Fall, 1985; Rev 2: Spring, 1986; Rev 3: Fall, 1986; Rev. 4: Spring,
1987; Rev 5 Fall, 1987; Rev 6 Fall, 1988; Rev. 7 Fall 1989; Rev. 8 Spring
1990; Rev. 10 Fall 1990; Rev. 11 Fall 1991; Rev. 12 Fall 1993; rev. 13 Fall
1996; rev. 14 Fall 1997
by
Dean P. Neikirk
Department of Electrical and Computer Engineering
University of Texas at Austin
Austin, TX 78712-1084 USA
tel (512)471-4669 or 471-8549
Preface
The Microelectronics Fabrication Laboratory has now been in operation here
at UT for eleven years; even so, it is still a lab course which requires
constant updating. This course has a number of objectives, chief among them
your exposure to basic silicon device processing. You will be required to
make use of information from many areas: solid state physics, chemistry,
electrical engineering, and computer science. Regardless of your future
intentions, we feel the material covered in lecture, and your experiences
in the lab, will be very valuable. The use of integrated circuits is pervasive,
and knowledge of how they are made is an important compliment to your knowledge
of how they can be used.
This laboratory is a synthesis of the work of a number of people. Similar
laboratories at Caltech (under the supervision of Prof. Jim McCaldin and
Prof. David Rutledge) and at the University of Illinois (originally developed
by Prof. Ben Streetman) have provided both inspiration and guidance. Industrial
support has been provided by Bell Laboratories, Advanced Micro Devices,
Motorola, and Texas Instruments. Both TI and Monsanto have provided silicon
wafers for our use. The Semiconductor Research Corporation has also provided
generous support for the development of our new mask set. The technical
staff (under the supervision of Mr. Harold Traxler and Marty Ringuette)
has provided invaluable assistance in setting up and maintaining the lab
equipment. The help of Philip Cheung, Doug Miller, Jeff Meitz, Stu Wentworth,
Carl Kyono, Doug Holberg, and Garrett Neaves in designing the experiments
is also gratefully acknowledged.
This lab is quite different from any other of the labs in your ECE curriculum.
The processing we do is very complicated, and there will be frequent, and
often very subtle, problems associated with it. You must be very patient
and methodical at all times. Since we have essentially only one set of equipment,
you must also be very careful. The lab is constantly evolving, and there
will be changes throughout the term as we get more equipment, develop new
experiments, and think of better procedures. Please feel free to make suggestions
that you think will help improve the lab.
This version of our lab manual for the World Wide Web is still under construction,
so please be patient. Also be warned that many of the files contain numerous
images that are quite large, so you may want to start with "auto load
images " OFF!
Dean Neikirk
Fall, 1996
Table of Contents
I. Introduction INTRO
A. Lab Notebooks and Reports 0-6
B. Grading 0-7
C. Safety 0-8
University of Texas Lab Safety Manual
UT Austin MSDSs on-line
II. Experiments
Introduction FABINT 1
Lab Schedule 5
Process Flow Summary 6
Processing Description PROCESS 8
Laboratory Report Guidelines REPORTS update 19
Report Updates: IMPORTANT! READ THIS!
Result Summary Tables 22-24
Device Testing TEST89 25
Holberg Mask Set MASKS 35
Device Tests Trouble Shooting TROUBLE 48
II. Operating Procedures
A. High Temperature Furnaces FURNAC A-1
B. Wet Oxidation WETOX B-1
C. Dry Oxidation DRYOX C-1
D. Boron Pre-Deposition BPREDP D-1
E. Phosphorus Pre-Deposition PPREDP E-1
F. Drive In Furnace DRIVE F-1
G. Vacuum Evaporation VACEVP G-1
H. Four Point Probe 4PTPR H-1
I. Hot Point Probe HOTPR I-1
J. Wafer Cleaning CLEAN J-1
K. Plasma Ashing PLASMD K-1
L. Photolithography LITHO L-1
M. Capacitance-Voltage Measurements CVMAN M-1
PCASP CV M-7
N. Junction Depth Measurements JUNCTD N-1
O. Mask Aligners MCROTCH O-1
P. Hydrofluoric Acid Etching HFETCH P-1
Q. Tektronix, Digital Curve Tracers TEKCT Q-1
PCASP IV Q-14
R. Ellipsometer ELLIP R-1
S. Microscopes, Line Measurements MCSCRP S-1
IV. Data Sheets page
Aluminum etch IV-1
Buffer - HF IV-2
Photoresist IV-3
PR Stripper IV-9
BN Wafer data sheet IV-13
P Wafer data sheet IV-15
V. Physical Constants page
Resistivity vs. Doping V-1
Kennedy & O'Brien Curves V-2
Nomograph for Abrupt p-n Junctions V-3
Physical Constants and Energy Conversions V-4
VI.Material Safety Data Sheets page
UT Austin MSDSs on-line
Introduction VI-1 Acetone VI-6 TCA VI-8 Photoresist VI-10 HMDS (used in PR adhesion promoter) VI-12 Hydrogen Peroxide VI-14 Hydrochloric Acid VI-16 Sulfuric Acid VI-18 Concentrated Hydrofluoric Acid VI-20 Buffered Hydrofluoric Acid VI-22 Aluminum Etch, Transene type A VI-25
Figures and Tables
Figures page
Holberg Mask Set 38-47
Rotameter type flow gauge A-2
3-zone furnace A-3
Flow calibration curve FT 22A01 tube, glass ball A-6
Flow calibration curve FT 22A01 tube, steel ball A-7
Flow calibration curve FT 2D02 tube, glass ball A-8
Flow calibration curve FT 2D02 tube, steel ball A-9
Oxidation rate, wet furnace B-2
Oxidation rate, dry furnace, TCE C-5
Oxidation rate, dry furnace,NO TCE C-6
BN wafer stacking arrangement D-1
Si surface after Boron Pre-dep D-2
Rs vs. Pre-dep time, Boron D-4
Rs vs. Pre-dep time, Phosphorus E-2
Constant/Limited Source Diffusion Profiles F-3
Erfc and Gaussian Diffusion Profiles F-4
Rotating vane vacuum pump G-1
Oil diffusion pump G-2
Vacuum Evaporation System G-4
Evaporation Sources G-5
Four Point Probe H-1
Plasma Asher K-4
Photoresist Processing L-2
MDC CBAX C-V system M-7
Curve Tracer Controls Q-7
L117 Ellipsometer R-5
Ellipsometer Thickness Periods R-9
Tables
Table I: Oxide Thickness Measurements 22 Table II: Sheet Resistance Measurements 23 Table III: Undoped Wafer Characterization 23 Table IV: Lithographic/Etch Resolution 24 Table V: Device Characterization 24 Furnace gas flow rates A-5 Furnace temperature controller settings A-5 Color Chart for Silicon Dioxide B-5 Evaporation materials G-9,G-10 Vapor pressures of the elements G-11 Tungsten wire resistance vs temp. G-12 Four-point probe diameter correction factors H-5 Four-point probe thickness correction factors H-6 Four-point probe current settings H-6 Curve Tracer Voltage Polarities Q-13 Ellipsometer Thickness Periods R-10