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Materials Science in Electronics devices
- Semiconductor devices -
2015 Yutaka Oyama
oyama@material.tohoku.ac.jp
http://www.material.tohoku.ac.jp/~denko/lab.html
Contents
・ Material issue of semiconductor devices and fabrication process
• Schematics of thin film growth (Molecular Layer Epitaxy, etc.)
・ Ultra fast and high frequency semiconductor electronic and photonic devices -1
• Ultra fast and high frequency semiconductor electronic and photonic devices -2
・ Crystal growth and semiconductor device epitaxy
・ Device grade evaluation of semiconductor crystals
半導体デバイスは、「金属・半導体・セラミックス」を総合して形成。理想型静電誘導トランジスタのプロセス例
METAL
35A
HEAVY DOPING
DOPING EPITAXY 1019-1020cm-3
(SURFACE STOICHIOMETRY CONTROL)
LOW-T& SELECTIVE
MOLECULAR LAYER EPITAXY (MLE)
WITH ATOMIC ACCURACY (AA)
HIGH QUALITY
REGROWN INTERFACE(SURFACE STOICHIOMETRY CONTROL)
LOW c CONTACT(METAL/SEMI CONTACT)NON-ALLOYED
VERY THIN MIXED LAYER
SELECTIVE EPITAXY
(SELF-ALIGN PROCESS)
ULTRA SHALLOW GROVE
LOW-T&DAMAGE ETCHING(PHOTO-STIMULATED GAS FLOW ETCHING)
LOW-T&DAMAGE SiN CVD
(REMOTE PLASMA CVD)
MISゲート{
DETAILED CRITICAL PROCESSES FOR ISITMETAL/CERAMICS/SEMICONDUCTOR BREAKTHROUGH PROCESSES
S/D=3.5nm
薄膜エピタキシャル成長
・液相エピタキシ
・気相エピタキシ
・超高真空エピタキシ
希薄環境相の結晶成長徐冷法ネルソン法温度差法
LED,LDなど発光デバイスの大量生産一般的にはミクロン・サブミクロンデバイスに適用高純度(偏析効果)・高品質低コスト
塩化物気相エピタキシ有機金属気相エピタキシ(MOVPE)
など
発光デバイス~トランジスタ・量子効果デバイスまでミクロン~サブミクロン~ナノ構造まで広範囲原料の高純度化気相反応+表面反応
分子線エピタキシ(MBE)
分子層エピタキシ(MLE,ALE)
ケミカルビームエピタキシ(CBE)
など
発光デバイス~トランジスタ・量子効果デバイスまでミクロン~サブミクロン~ナノ構造まで広範囲原料の高純度化表面反応
LPE
Liquid phase epitaxy
VPE
Vapor phase epitaxy
UHV
Ultra high vacuum
epitaxy
Thin film epitaxial growth
Detailed reaction processes of Epitaxial growth
・Si_react
Vapor phase or solution reaction
Diffusion to the surface
Surface adsorption
Surface reaction
Surface diffusion
(migration)nucleation
desorption
Real surface reaction
process in MLE Si
Spiral growth necleus centers on facets
LPE GaAs (screw dislocation)
Principle of MLE :GaAs case
Molecular Layer Epitaxy in brief
ALE(Atomic Layer Epitaxy) of poly-ZnS on glass substrate for EL application
T. Suntola, U.S. Patent 4058430, 1977.
M. Ahonen, M. Pessa, T. Suntola, Thin Solid Films 65 (1980) 301.
MLE(Molecular Layer Epitaxy) of GaAs single crystal on GaAs
J. Nishizawa et. al. Extended Abstracts of the 16th Conference on Solid State Device and Materials
(The Japan Society of Applied Physics, Kobe, Japan, 1984), p. 1.
J. Nishizawa, et. al. J. Electrochem. Soc., 132 (1985) 1197.
Molecular layer epitaxy of GaAs
Thin Solid Films, 225 (1993), 1-6.
Jun-ichi Nishizawa, Hiroshi Sakuraba Yutaka Oyama など
Principle of MLE
Mono-molecular layer epitaxy
Self-limiting epitaxy with atomic accuracy (AA)
Area selective epitaxy
表面反応Surface reaction process
Impurity doping: control of surface stoichiometry
Electrical activation of Te and Se in GaAs at extremely heavy doping up to 5×1020cm-3 prepared by
intermittent injection of TEG/AsH3 in ultra-high vacuum,
Journal of Crystal Growth, Volume 212, Issues 3-4, May 2000, Pages 402-410
Yutaka Oyama, Jun-ichi Nishizawa, Kohichi Seo and Ken Suto など Ohno T et. al.
0
0.5
1
1.5
2
2.5
DEZn Pressure (Torr)
Car
rier
Co
nce
ntr
atio
n (
cm-3
)
Gro
wth
Rat
e (A
/C
ycl
e)
AA Mode(C.C.)
AA'Mode(C.C.)
IG Mode(C.C.)
10
10
10
10
20
19
19
18
1x
5x
1x
5x
10 10 10 10-6 -5 -5 -4
3x 1x 3x 1x
Hole concentration vs. DEZn pressure for Zn doping for temperature synchronized MLE.
Zinc doping of GaAs grown with temperature synchronized molecular layer epitaxy
AsH3 AsH3DEZn TEG
evacuation evacuation evacuation evacuation
time
Tem
per
ature
temperature synchronized molecular layer epitaxy
AA' - after arsine doping mode
precursor injection phases
360 380 400 420 440 4600
1
2
4
AA Mode
AA'Mode
IG Mode
undoped
10
10
10
17
18
19
2x
1x
1x
3
Substrate temperature during AsH3 injection [・C]
Ho
le c
on
centr
atio
n
[cm
-3]
Gro
wth
rat
e per
cycl
e [
・]
Growth rate and hole concentration vs. temperature during arsine injectionfor Zn doped GaAs grown with temperature synchronized MLE.
file: d:\0q\fig_s56s.cdr ZnTS.cdr
DOPING CHARACTERISTICS OF p-GaAs:Zn MLE
Doping mode dependences of impurity concentration evaluated by one-epitaxial run: base DETe doping.
Extremely high and steep impurity profile
▲Te DOPING
○Se DOPING
UP TO 1021cm-3 IMPURITY CONCENTRATION
5x1019cm-3 ELECTRON CONCENTRATION
Required for nm-channel Tr.
DOPING CHARACTERISTICS OF n-GaAs MLE
DOPING CHARACTERISTICS OF p-GaAs:Be MLE
0 10 20 30 40 50 601018
1019
1020
1021
Be
co
nce
ntr
atio
n (c
m-3
)
Be(MeCp)2 injection time (sec)
●AA ■AG
UP TO 4x1020cm-3 IMPURITY CONCENTRATION
8x1019cm-3 HOLE CONCENTRATION
Required for nm-channel Tr.
Ohno T et. al.
Ultra low c metal/semiconductor contact:
non-alloyed and selective CVD by W(CO)6
XTEM of MS interface with atomically
flat interface
Low-resistance Contacts with Chemical Vapor Deposited Tungsten on GaAs Grown by
Molecular Layer Epitaxy
[J. Electrochem. Soc., 146 (1), (1999), 131 - 136]
Yutaka Oyama, Piotr Plotka, Fumio Matsumoto, Toru Kurabayashi, H.hamano,
Hideyuki Kikuchi and Jun-ichi Nishizawa など
Contact resistivity for n-GaAs (MLE grown)
Also for p-GaAs (down to 10-8Wcm2 order)
Almost the limit of TLM method
High quality regrown interface
"Optimization of low temperature surface treatment of GaAs crystal",
J.Nishizawa, Y.Oyama, P.Plotka and H.Sakuraba,
Surface Science, 348, 105-114 (1996). など
Good interface
No trace of oxides and carbide after optimized
surface treatment
QMS desorption analysis
Also by XPS analysis
High quality regrown interface: chemical analysis
[110]
[11
0]
{001}
R
F
R
R
R
F
F
F
F
FF
F
R
R
R
R
F
F
F
F
F
F
F
F
TOP VIEW
Regrown p+-GaAs:Be 1st n+-GaAs:Te&S
epitaxy (49nm)
1st n+-GaAs:Te&S
epitaxy (49nm)
S.I.GaAs
Ti/Au non-alloyed
contact
Sidewall tunnel junctions
(regrowth interface)
Sidewall tunnel junction
(regrowth interface)
CROSS SECTIONAL VIEW
RF F
Figure 1. Schematic drawings of the cross sectional and top view of the fabricated sidewall
tunnel diodes. “F” and “R” mean the first epitaxial layers and the regrowth layers. The
arrows indicate the positions of sidewall regrown tunnel junctions. Large pad has 100mm
in length, and small one has 50mm.
Application of MLE GaAs to high quality
ultra-small tunnel junctions
Side-wall regrowth process
Application of low-temperature area-selective regrowth for ultrashallow sidewall GaAs tunnel junctions
Yutaka Oyama, Takeo Ohno, Kenji Tezuka, Ken Suto and Jun-ichi Nishizawa
Applied Physics Letters, 81, 2563-2565 (2002). など
Ti/Au
non-alloyed
contact
n+-GaAs:Te&S layer
(50nm)regrown p+-GaAs:Be layer
SI GaAs substrate
sidewall
tunnel junction (SJ~10-8cm2)
100 nm
1 mm
n+-GaAs:Te&S
p+-GaAs:Be
Application of MLE GaAs
to high quality ultra-small
tunnel junctions
Side-wall regrowth process
Figure 2. J-V
characteristics of GaAs
sidewall tunnel junctions at
290 and 77K on (a) normal
mesa, (b) 45° inclined
configuration and (c)
reverse mesa sidewall
orientations.
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70.0
5.0x103
1.0x104
1.5x104
2.0x104
2.5x104
3.0x104
3.5x104
290K
77K
NORMAL MESA ORIENTATION
Curr
ent
Den
sity
[A
cm-2]
Voltage Bias [volts]
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70.0
5.0x103
1.0x104
290K
77K
45° INCLINED
CONFIGURATION
Curr
ent
Den
sity
[A
cm-2]
Voltage bias [volts]
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.70
1x103
2x103
3x103
4x103
5x103
290K
77KREVERSE MESA
ORIENTATION
Curr
ent
Den
sity
[A
cm-2]
Voltage Bias [volts]
Record high peak current density
Current-voltage characteristics of sidewall TUNNEL junctions
Sidewall mesa orientation dependences
Ohno T et. al.
(Jin, 2003)
● Our results:2002
GaAs tunnel diode (PVCR=28)
(Ahmed, 1997)
Figure of merits of fabricated TUNNEL junctions
RITD:
Resonant Interband Tunnel diode Ohno T et. al.
0 200 400 600 800 1000 1200 1400
1018
1019
1020
tunnel junction
(regrown p+-GaAs:Be/n
+-GaAs:Te&S interface)
epitaxial/substrate
interface
Be
S
Te
Impuri
ty c
oncentr
ati
on [
cm-3]
Depth from the surface [A]
Very high & steep impurity profile at tunnel junction interface
up to 2x1018cm-3 impurities /A Ohno T et. al.
Ultra fast and high frequency semiconductor electronic
and photonic devices
To be continued to next week
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