MICROELECTRONICS

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MICROELECTRONICS (Short lecture
course) O.G. Vendik Department of Physical
Electronics and Technology St.-Petersburg
Electrotechnical University St. Petersburg
197376, Russia, E-mail ogvendik_at_mail.eltech.ru
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Lecture 1
1. Introduction. What a role does the
microelectronics play in life of the modern
society? 2. Field effect transistors as the basis
of the modern microelectronics. 3. Manufacturing
technology. Photolithorgaphy 4. Heterojunctions.
2-D electron gas. HEMT. 5. Charge coupled
devices. 6. Conclusion
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1. Introduction
What is the microelectronics? What is the
integrated circuit? Competition of transistors
and integrated circuits with vacuum valves. What
a role does microelectronics play in life of the
modern society?
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What is the microelectronics?
Microelectronics is a part of modern electronic
technology
Microelectronics includes as its components the
design, manufacture, and use of integrated
circuits.
The integrated circuit is a monolithic functional
block formed as an intelligent combination of a
very large number of semiconductor transistors
and metal interconnections.
Integrated circuits can be designed not only on
the base of semiconductors, but also on the base
of superconductors, ferroelectrics, or ferrites.
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The use and development of the integrated
circuits
The most important area of use or application of
the integrated circuits is the design and
manufacturing of electronic digital computers
With certainty we can proclaim that the
development of the electronic digital computers
was impossible without the integrated circuits
The first electronic digital programmable
computer was based on the vacuum valves and
included approximately 20 000 double triodes.
Such a computer was started up in the USA in
1946.
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Vacuum-valve computer and modern laptop
Several millions of transistors
20 000 vacuum valves
Laptop, 2005
VVC Ural, photo of 1960
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The first experiment with transistor
Transistor was developed in 1948 by John Bardeen,
Walter Brattain, and William Shockly at Bell
Laboratory (a Nobel prize in 1956)
The device was a combination of two junctions pn
and np
The word is a combination of two words transfer
and resistor
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The Moors law, which powers the progress of the
microelectronics
Gordon Moor, born in 1929
The Moors law Each year the number of active
components in an manufactured integrated circuit
is doubled
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The first prototype of an integrated circuit
(transistor, two resistors, and capacitor on a
single peace of silicon), was demonstrated at
Texas Instruments by Jack S. Kilby, 1958. (a
Nobel prize in 2000)
Modern integrated circuit comprising
approximately 100 000 transistors manufactured on
a single peace of the silicon wafer S 6x6 mm2
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Portion of active components of a certain type
used as a basis of digital devices down the years
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Growing time of different types of active
components as a basis of digital devices
Question Why does one observe a deceleration of
developing the next type of electronic
devices? Answer Because of increasing the make
quantity and necessity to rearrange the
production equipment for a new type of devices.
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The problem, which cannot be solved without a
new idea?
Transistor effect was discovered in 1948. At the
beginning, the transistors as electron devices
were in competition with vacuum valves. The very
important problem (computer!) could not be solved
without transistor. Size, weight, power
consumption of vacuum valves!. Transistor won the
competition. There was a huge market for the
computers. That was followed by a development of
the microelectronics. The microelectronics
technology provided computerisation of the human
society. Now we should say about cellular
telephones as well!
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Production of microelectronics goods is an
essential part of the world economics
The sale of the microelectronics goods in the
whole world reached in 1997 the level of 150
billions of the USA dollars
That is comparable with amount of the sale in
other powerful sectors of economics like gas,
oil, and nuclear power energetics
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2. Field effect transistor
The structure of Field effect transistor Electron
(n) or hole (p) conductivity of a
semiconductor Complementary Metal Oxide
Semiconductor Field Effect Transistor Road map of
integrated circuit fabrication Production
efficiency
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Field effect transistor
That is characteristics of FET on the level of
1970
n-channel FET
If the GS voltage drop is positive, the electrons
are attracted and the holes are repulsed. Under
the gate, the conductive n-channel is formed
lc is the length of the channel, that is the most
important parameter of FET
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Electron (n) or hole (p) conductivity of a
semiconductor
The required type of conductivity is provided by
doping. The following dopants should be considered
For silicon (Si) p-type conductivity is provided
by acceptors 1) Boron (B) 2) Aluminum (Al) 3)
Gallium (Ga)
For silicon (Si) n-type conductivity is provided
by donors 1) Phosphorus (P) 2) Arsenic (As) 3)
Bismuth (Bi)
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CMOSFET
Complementary Metal Oxide Semiconductor Field
Effect Transistor
In equilibrium state the current through the
block equals zero
The block of n-FET and p-FET is very advisable on
the requirement of the energy supply consumption
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The length of channel of CMOSFET in production of
the advanced industrial companies
lc
,
nm
500
Prognosis of 1994
100
Realization
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Prognosis of 2001
? ? ?
Realization
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10
2005
2007
2009
2011
2013
2015
2003
1997
1999
2001
1995
YEARS
10 nm 30 atomic layers
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(No Transcript)
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X-ray photograph of many level wiring
X-ray photograph of integrated circuit of 1965
1 ?m
1.2x1.2 mm2
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Short gate MOSFET structure
Electron microscope picture of the MOSFET
structure
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Questions to Lecture 1

• What is the integrated circuit?
• When and where the transistor effect was
  discovered? Who were discoverers? How were they
  awarded?
• What kind of transistors are used as a basis of
  the modern microelectronics?
• What means the abbreviation CMOSFET?
• Why the CMOSFET is preferable in design of the
  large modern integrated circuits?
• What is the Moors law?
• What is the characteristic parameter of FET? What
  is the numerical value of the parameter?
• What elements are used as a typical dopant in
  silicon transistors?

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Lecture 2. Manufacturing technology
Silicon boule growing Silicon wafer
machining Photolithorgaphy Selective etching
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The wafer of 300 mm diameter 2004, Intel
Corporation
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The wafer after processing
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Oxide masking, mask photolithography and
selective etching
Ultra-violet light
SiO2 is the silicon dioxide
Opaque area
Photomask
Photoresist
The silicon dioxide is widely used in FET
technology 1) Isolating layer under the gate 2)
Masking layer in the etching process
SiO2
Si
After selective etching
Through the window the doping can be made
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Projective photolithography
Eximer lasers
Wmin is resolution of the lithography
Laser interferometer is used for superposition of
the recurrent lithography operations
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Technical control of the integrated circuits
Defected units are marked with the black points
Contacting probes for examining the integrated
circuits on an uncut wafer
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Production efficiency
Production efficiency (yield ratio) are in the
range from 1 till 90
In order to have the market rigged, the
following ideas are spread out by the advertising
service 1) Each computer in the hand of
consumer is an old one by definition 2) Each
integrated circuit being in a production process
is not large enough by definition
Increasing the production efficiency needs
to use more perfect equipment, which is more
expensive. Industrial companies are prompted
to manufacture more complicated integrated
circuits and to change the equipment
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Questions to Lecture 2

• What is thickness and diameter of the wafer used
  in production of silicon integrated circuits?
• How the silicon wafer is produced?
• What parts does the mask photolithography process
  consist of?
• What are the main points of the liquid etching
  process ?
• What is the ion beam etching?
• What are the main tools used in the projection
  photolithography process ?
• What is the resolution of a lithography used in
  production of the large integrated circuits?
• What is the definition of an yield ratio in
  production of the large integrated circuits?

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Lecture 3. Heterojunction microelectronics
1. Heterojunctions. 2. HBT 3. 2-D electron gas.
4. HEMT.
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Cross section of a typical III-V heterojunction
bipolar transistor
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The heterojunction (HJ) is contact between two
semiconductor crystals with identical crystal
lattices and different energy band gaps
Eg, eV a, A GaS 0.73
6.095 GaAs 1.43 5.654 InP 1.26
5.869 AlAs 2.16 5.659
Piece of Mendeleevs table
GaAs, AlAs, and (Al,Ga)As can form AIII - BV HJ
HJ is manufactured usually by liquid-phase epitaxy
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Stannum, Stibium, Plumbum
Stannum or Tin A tin of beans, Straight from
the tin- something which is absolutely fresh
What they want here is Yankee twang straight
from the tin. (Evening News). Twang is an
American version of the British Cockney
Plumbum or Lead. Lead plug, Lead
bullet Brass is an alloy of copper and lead.
Pewter is an alloy of tin and lead. A pewter
cup for drinking bear
Stibium or Antimony GaSb is the gallium antimonide
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Energy band diagram of AlGaAs/GaAs HBT.
Due to the wide bandgap emitter, for a given
bias, the energy barrier seen by holes injected
into the emitter is higher than that for
electrons injected into the base.
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Energy band diagram for the wide band gap emitter
HBT
Conduction band Energy gap Valence band
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Super-injection
EC
EV
NC is the effective n-charge density
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The landmarks of the history
H. Kroemer, Theory of a wide-gap emitter for
transistors, Proc. IRE, Vol. 45, No. 11, pp.
15351537, 1957.
Zh. Alferov, Experimental realization of
GaAs-(Al,Ga)As hetrojunction, 1965, A.F. Ioffe
Physico-Technical Institute
H. Kroemer and Zh. Alferov were awarded the
Nobel prize in 2000 for Developing semiconductor
heterostructures used in high-speed- and
opto-electronics
III-V heterojunctions are now widely used for
production of photodiodes, heterolasers, and HEMTs
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Laureats of the Nobel prize
Prof. H. Kromer, University of California, Santa
Barbara
Prof. Zh. Alferov, A.F. Ioffe Physicotechn.
Inst., Saint Petersburg
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2-D electron gas
Energy band diagram of the junction between
n-(Al,Ga)As and p-GaAs
2-D electron gas, n ? 1019cm-3
n-(Al,Ga)As p-GaAs
Spacer is undoped (Al,Ga)As without scattering
centers
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Mobility of 2-D electron gas
1- Si, n ? 1017cm-3, 2 - GaAs, n ? 1017cm-3, 3
-GaAs, n ? 1014cm-3, 4 - 2D-electron gas
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High Electron Mobility Transistor
The HEMT structure is formed by growing the
AIII BV epitaxial layers
Metalization
Isolator (Si3 N4)
Drain
Source
Gate
n-GaAs
n-(Al,Ga)As
p-GaAs
Isolation layer
Substrate (semi-isolated GaAs)
2D electron gas layer
Length of the channel lC 0.25 mm. Resistance
of the channel RC 3 Ohm
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Output characteristic of HEMT
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Effective noise temperature of HEMT at microwave
frequency region