ELECTRONIC MATERIALS
Soochow University
2009
In Profile - Huang
• More than 30 years: electrochemistry
research
• and surface chemistry (Sep. 1975)
• Near 30 years: WA
• Near 30 years: AESF
• More than 20 years (from July 1986): CSIS
• And others
Contents
•
•
•
•
•
•
•
•
•
•
•
Introduction
Wire & Cable
Semiconductor
Capacitor
PCB
MEMS
Battery
CD-R
EMI/RFI
ITO
Electrowetting, LCD &LED
Introduction
Electronic Materials
Basic structures of solids
a. electron orbitals
b. energy bonds
c. crystal structures: bcc, fcc….
d. crystal solids:
bcc, -Fe V Cr Mo W
fcc, -Fe Al Ni Cu Ag Pt Au
hcp, -Ti Zn Zr
metal oxides or nitrides…: ceramics
e. polycrystalline & noncrystalline solid
polycrystalline: for example PVD
amorphous solids: the atoms or ions
are arranged randomly, hence there
are dangling bonds (incomplete
energy bonds) and voids. In general,
stable only up to a certain temp.
polymers: partially crystalline and
partially amorphous
f. phase diagrams
g. Techniques for crystal growth &
thin-film deposition: Czochralski
growth of semiconductor
h. crystal imperfections: defect and
impurity
i. diffusion in solids: depends on
the size difference between the
impurity and the host atoms (or
ions) via vacancy or interstitial
Wire and Cable
Wire & Cable
•
•
•
•
WA: The Wire Association International
Ag: 1.49 -cm at 20oC
Cu: 1.72 -cm, OFHC 0.008%O2
Cu alloy: TS (tensile strength)
1.2-1.4%Cd, 200% TS, 85-90% 
<10% Sn, P & Si, 3-400% TS, 40-50% 
2-2.5% Be, Ag
• Al: 99.3% purity
45% TS, 62% , 30% density
Au:
Rod quality
Wire breaks
Wire drawing
Drawing force
Lubricants
Optical fiber
• Core: fused mixtures of metal oxide
3 – 80 μ
• Cladding material: low n
20 – 50 μ
Total reflection at the cladding-core material.
Optical fiber
Semiconductor
90, 65, 55, 45 nm
semiconductor
• 1. physics
classification of materials:
insulator
metal
semiconductor: electron and hole
conduction, the resistivity of silicon
depends upon the number of acceptor or
donor atoms added and the temperature
2. Wafer preparation
a. sand: silicon dioxide containing less than 1 %
impurities.
b. react with carbon:
SiO2 + C → Si(99% purity) + CO2
c. react with hydrogen chloride:
Si + 3HCl → SiHCl3 + H2
d. decomposed using electric current:
SiHCl3 + H2 → Si(ultrapure polycrystalline) +
3HCl
e. Silicon crystal growth: Czochralski method
CZ method
• Si at 1415oC in a rotating quartz crucible
→Add the desired impurities
→An arm with a piece of seed crystal with
the Si
→Ar is used to prevent contamination of the
molten Si
→The seed crystal is slowly withdraw from
the molten Si
CZ拉晶法
• CZ拉晶法：
CZ (Czochralski) 法進行單結晶矽之生產；此方
法目前被工業界廣泛地使用於大尺寸單結晶之製
造。此法先將原子排列不規則之多結晶矽原料在
高溫下熔化 (Meltdown) ，再以單結晶之晶種
(Seed) 慢慢浸入矽熔湯中，經過晶頸生長 (Neck
Growth) 、晶冠生長 (Crown Growth) 、晶身生長
(Body Growth) 、尾部生長(Tail Growth)等製程，
即可得到與晶種相同之排列整齊之晶格、原子，
成為製造矽晶圓所需要之單結晶材料。
wafer
• Orientation: XRD provides the orientation
• sawing: thin slices (wafer)
• Polishing: one side is mirror-like finish
3. Epitaxial deposition
• Is the deposition of a single crystal layer on a
substrate (same composition). Etchant (HCl gas)
is used to create nucleation site for epitaxial
deposition
Method of epitaxial deposition:
sputtering, evaporation: low rate
vapor growth: deposited from SiCl4 and SiH4
(better from hydrogen reduction
SiCl4(g) + H2(g) = Si + HCl(g) or pyrolysis of
SiH4(g) = Si + H2(g)
4. Oxidation
• The ability to grow a chemically stable
protective layer of SiO2 on Si, makes Si
the most widely used semiconductor.
• This protective layer is growth in
atmospheres containing either oxygen or
water vapor (faster) at temp. in the range
of 900 – 1300oC.
5. Impurity introduction: by diffusion
• A. predeposition: heat semiconductor to a
temp. and an excess of the desired dopant
is made available at the surface of the
wafer. The dopant will enter the crystal
lattice. Solid solubility. Ion implanation:
take ions of a desired dopant, accelerates
them using an electric field.
• B. drive-in: is performed in a high temp.
diffusion furnace.
6. Photomasking
• For the successful transfer of an image to the
surface of a wafer: generate a mask and transfer
to the wafer through use of a photoresist (光阻).
• The circuit be fabricated by sequentially
transferring images the wafer while performing
steps such as CVD, epitaxy, predeposition, and
drive-in, or metallization between successive
image transfers.
• Light-hardened resist is negative resist, while
light-softened resist is positive resist.
Basic photoresis flowchart
• Surface preparation – application of
resist – soft bake (low temp. cure to dry
resist, expose, develop (dissolve the
unpolymerized resist)) – visual
inspection – hard bake (higher temp. cure
to completely dry and polymerize) – etch –
strip resist – visual inspection
7. Chemical vapor deposition
• The formation of a stable compound on a
heated substrate by the thermal reaction
or decomposition of gaseous cpds.
• SiH4 + heat = Si (polycrystalline)+ H2
• SiH4 + O2 = SiO2 + H2
• SiH4 + NH3 = Si3N4 (a dense dielectric
used to passivate circuits) + H2
8. Metallization
• After the devices in the silicon substrate
have been fabricated, they must be
connected together to perform circuit
functions.
• Vacuum deposition of Al by sputtering
• Copper deposition
STM, 15 x 15 nm2
MEMS
Microelectromechanical systems
nm?
電 鑄
Electroforming
Since 1858
Cyclic voltammetric stripping
analysis, CVS
CVS
•
•
•
•
Potentiostat and three-electrode:
A platinum wire auxiliary
A saturated calomel electrode (SCE)
A rotating platinum disc of area 0.071 cm2.
The disc was rotated at 2500 rpm and
swept continuously at 10 mV/sec between
-0.150 and 1.850 V vs. SCE in solution.
Relative rate parameter, Ar/As
• The area under the stripping peak (Ar)
corresponds to the charge required to
oxidize the deposit completely and is
proportional to the average deposition rate
of copper, whereas As is the strippping
peak for the static electrode without any
additive.
印刷線路版
PCB
Image transfer
etching
lamination
Copper through hole plating
Solder plating
電容, capacitor, condenser
•
•
•
•
•
•
Ta
MOS capacitor, fig. 55
Ceramic
Al/oxide
Paper
mica
Energy density
Wh/kg
Work density
Kw/kg
Li battery
100 - 125
< 0.2
Ni-H battery
50 - 60
< 0.2
Acidic lead
battery
30 - 40
< 0.2
capacitor
0.17
50
V = E, Q ∞ V, C = Q/V
• F, farad
• μF
• μμF = pF = 10-12F
•  values:
PbLaZrTiO3
TiO2
Ta2O5
Al2O3
1000
50
25
9
Solid tantalum capacitors
• Capacitor that use a metal oxide film
having a valve effect as a dielectric are
known as electrolytic capacitors. Because
their dielectric film is extremely thin,
electrolytic capacitors are the smallest of
all capacitors in terms of volume per unit
capacitance.
Ta capacitor
• Dielectric strength:
breakdown voltage =
working voltage
glass: 90 kV/mm
mica: 200 kV/mm
Ag paste, cathode
graphite
MnO2
Ta2O5
Ta, anode +
Sintered Ta Powder
Tantalum oxide is formed by
electrochemical technique on tantalum
as the metal electrode, which serves as
the dielectric. On the top of the tantalum
oxide a manganese dioxide layer is
formed as electrolyte. Solid electrolyte
capacitor. To make sure that this
manganese dioxide is electrically
connected, a graphite layer is provided to
create a metal layer that serves as a
cathode.
Sintered Ta, 2 – 10 μm
Ta powder is compressed under
high pressure around a Ta wire to
form a pellet. This is subsequently
vacuum sintered at high
temperature (typically 1500 –
2000oC). This structure is of high
mechanical strength and density,
but is also high porous giving a
large internal surface area.
Construction of solid Ta capacitors
Neocapacitor (conducting polymer
tantalum capacitor)
High conductivity 20 S/cm, high
temp. for thermal decomposition
200 – 300oC
CD 等光碟族
CD族
•
•
•
•
Glass master: 玻璃基版
Metalizing: 電鑄
Stamper: 壓模
Injection molding,
optical polycarbonate,
sputtering
• Lacquering: 塗漆層
• Printing: 印刷
CD 族
•
•
•
•
•
•
•
CD-ROM
CD-R
CR-RW
DVD-ROM
DVD-R
DVD-RW
DVD-RAM
針孔
EMI/RFI Shielding
• Electromagnetic interference:
conducted emission
radiated emission
EMI
Indium tin oxide, ITO
• High conductivity (about 104 -1cm-1)
from the creation of a conducting carrier-oxygen
vacancy with the addition of dopant Sn to the
matrix In2O3.
• High transparency (85 – 90%)
The crystallite size of ITO powder
• Could be calculated from the line
broadening of the (222) diffraction line
according to the Scherrer equation:
D = 0.9λ / cos
where D is the crystallite size (in angstroms), λthe
wavelength of Cu K1 radiation, and  the corrected halfwidth of the diffraction peak.
ITO powder
• =0.456o
• D= 18 nm
Electrowetting
• Electrowetting: a voltage is used to modify
the wetting properties of a solid material
• Without a voltage: the requirement of
spreading is s > sl + l
• With a voltage:
cosΘv = cosΘo + V2/2 wo d
Surface tension, dyne/cm
•
•
•
•
•
•
Water, 72.6
Fluoro-polymer, 8-15
Hydrocarbon-polymer, 18-30
Molten glass, 200-400
Molten metal, 350-1800
Detergent solutions, 24-40
Battery
• History
• Li battery
• Polymer electrolyte
• Thermal battery
Construction for Polymer
electrolyte
•
•
•
•
Al foil
Anode: C (LixCn = Li+ + e + Cn)
Anode material
Polymer (gel polymer, monomer and
electrolyte)
• Cathode material
• Cathode: Li, Co oxides
• Al foil
Thermal battery
Thermal battery
• The conductivity of eutectic point of LiCl-KCl is
2.1 (Ωcm)-1, while aqueous NaCl is only 0.2.
• Plus:
more than 10 years
less than 1 sec
high charge rate
reliability
maintenance
Thermal battery
• Two main types: Li and Ca systems
Li/LiCl-KCl/FeS2
Ca/LiCl-KCl/CaCrO4
(when 61% LiCl, then m.p. is 352oC)
Reactions:
Li + FeS2 = Li2Fe2S5 + FeS
Ca + CaCrO4 = CaCl2 + Cr2O42CaO
Thermal battery
• Thermal source: paper and sheet
a. Thermal paper:
1-10 μm powder of Zr and BaCrO4
burning rate is 10-15 cm/sec
thermal content is 1675 j/g
b. Thermal sheet:
KClO4 and Fe powder
excess iron powder is a conductor
thermal content is 920 -1420 j/g
LCD, liquid crystal display
判別液晶種類
(homeotropic組織=全部液晶分子垂直排列於玻璃上)
Pixel, picture element
•
•
•
•
•
Vertical polarizing filter film
ITO, transparent electrode
Twisted nematic LC
ITO, transparent electrode
Horizontal polarizing filter film
具有光學異方向性的物質第四態
Plasma display pane
cost
• 70%:
1. 背光模組37%
2. 彩色濾光片27%
3. 偏光板15%
4. 驅動 IC 8%
5. 玻璃基板7%
物理蒸鍍法直接獲取金屬精密圖案
• Image: dry film or photoresist
• Metal pattern: sputtering
• Stripping of dry film or photoresist
sputtering
•
濺鍍的基本原理是將加速了的離子轟擊固體
表面，離子在和固體表面的原子交換動量之後，
就會從固體表面濺出原子，此現象為濺射
(Sputtering)。濺射是真空鍍膜方法之一。通常
陰極(cathode)上裝載的是靶材(target)，而陽極
(anode)上裝載的則是待鍍物(試片基板或碟片)。
為使於濺鍍氣體(sputtering gas)中電漿(plasma)
能夠點燃，將陰極加到數百伏特電壓。陰極所加
的電壓相對於陽極而言是負的，因而游離的氬正
離子被加速往陰極表面飛去。當氬正離子與靶材
表面發生碰撞時，靶材表面原子被撞擊出而飛向
置於陽極的基板並鍍在基板表面。
target
Sputtering target
•
Pure Metal Sputtering Targets
Aluminum/Al, Silver/Ag, Gold/Au, Lanthanum/La, Cerium/Ce, Cobalt/Co,Carbon/C,
Chromium/Cr, Copper/Cu, Dysprosium/Dy, Erbium/Er, Europium/Eu, Gadolinium/Gd,
Holmium/Ho, Hafnium/Hf , Indium/In, Iridium/Ir, Lutetium/Lu,
Magnesium/Mg,Molybdenum/Mo, Niobium/Nb, Neodymium/Nd, Nickel/Ni,
Praseodymium/Pr, Palladium/Pd, Platinum/Pt, Rhenium/Re, Ruthenium/Ru,
Rhodium/Rh, Scandium/Sc, Silicon/Si, Samarium/Sm , Tantalum/Ta, Terbium/Tb,
Titanium/Ti, Thulium/Tm, Vanadium/V, Tungsten/W, Ytterbium/Yb, Yttrium/Y,
Zirconium/Zr
•
Alloy Sputtering Targets
Rare earth TbDyFe alloy, Al-Ag, Al-Si, Ag-Pt, Ag-Cu, Ce-Gd, Cu-Ce ,Ce-Sm ,Co-Zr ,
Co-Cr , Co-Ni , Co-Pd , Co-Fe , Cr-V , Cr-B , Cr-Cu , Dy-Fe , Gd-Fe , In-Sn , Ir-Rh ,
Ir-Pd , Ni-Fe , Ni-Ti , Ni-V , Ni-Cr , Mn-Ir , Mn-Fe ,Mn-Ni , Tb-Fe , Ti-Al, W-Si , Zr-Ti,
Zr-Ni , Zr-Nb , Zr-Al , Zr-Cu , Zr-Y , Zr-Hf , Ga-As , Gd-Fe-Co , Nd-Dy-Fe-Co , Tb-FeCo , Co-Ni-Cr , Al-Si-Cu , Tb-Gd-Fe-Co
•
Compound targets/ Ceramic Sputtering Targets:
TiO2, CaO, SiO, Ta2O5, La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3 ,Eu2O3, Gd2O3,
Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Sc2O3, Y2O3, CeF3, NdF3,
YF3, LaF3, YbF3, MgF2, Nb2O5, ZnS, In2O3, ITO targets, Al2O3 ，CaF2， GaP ，
LaAlO3, LiNbO3, LiTaO3, MgO, MgF2, SrTiO3, SiO2 , YSZ , HoBCO， ITO, MgO,
SiC, SmBCO, SiO2，YBCO, ZnO, ZrO2
直接獲取金屬精密圖案的物理蒸鍍室
鈔票上的細條紋
0.05mm寬(508 lpi)
鋁金屬圖案的精密度
•例1
(F6液體溶劑於PC塑膠板上的110倍圖)
其A線條寬為0.064 mm，有每英吋397線(lpi)的精密度，而B線條更細
至0.027 mm，即有每英吋940線(lpi)的高精密度。
•例2
(IPA液體溶劑於ABS塑膠板的50倍之圖)
其A線條寬為0.08 mm，有每英吋318線(lpi)的精密度，而B線條更細
至0.027mm以下，意即有每英吋1270線(lpi)以上的高精密度。
F6液體於PC塑膠板上的圖案之放大110倍照片
液體溶劑(a,b)在底材上的接觸角。
PC塑膠片於真空鍍鋁後的塗有F-3溶劑處之3D
掃瞄功能表面形貌量測儀的量測圖。
LED, light-emitting diode
• A chip of semiconducting material doped
with impurities to create p-n junction.
Charge-carriers (i.e. electrons and holes)
flow into the junction from electrodes with
different voltage. When an electron
recombines with a hole, it falls into a lower
energy level and releases energy in the
form of a photon.
LED, light-emitting diode
• Light source
The efficiency of a standard W-filament light bulb is only 5%, so 95%
is lost as heat.
The fluorescent tube is 15 – 25%.
In Tailand, lighting accounts for 40% of all electricity consumption.
A US Department of Energy report states that if 50% of the lighting in
the USA were replaced by white GaN-based LEDs, 41 GW of
electricity would be saved (41 power stateions). – Greenhouse
• Indium gallium nitride/gallium nitride,
(InGaN/GaN), stay cool, very little heat
LED, light-emitting diode
• Blue LEDs are based on one or more InGaN
layers sandwiched between thicker layers of
GaN.
• By varying the relative InN-GaN fraction in the
InGaN, the light emission can be varied from
violet to amber.
• White light LEDs are fabricated by coating the
surface of blue LEDs with a yellow phosphor.
Coating?
• Non-radiative recombination: dislocation?
LEDs
• Low energy consumption
• Long life
trafic lights are replaced every 6 months
while LEDs can last 10 years
• Low maintenance
White LEDs
• Home and office lighting:
high efficiency, 30%: 60% in lab and for the future is 80%.
• High quality
• Long life:100,000 hr, but packaging?
• Low cost: white LEDs are more expensive than
filament light bulbs and fluorescent tubes