Basic 2Basic 2Anisotropic Wet-etching
of Silicon: Characterization and Modeling of ChangeableModeling of Changeable
Anisotropypy
Prof K SatoProf. K. SatoDept. of Micro/Nano Systems Engineering
Nagoya University
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Orientation Dependent Etching(Conventional Products)
〈110〉
〈111〉
〈112〉
〈100〉 SiO2〈111〉
〈100〉 SiO2
Si
Diaphragm
Deep grooves on a (110) wafer Diaphragm on a (100) wafer
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Variation in etching profile on (100) silicon wafer
Groove Wall Orientations(111) (100) (110)(111) (100) (110)
KOHTMAH
KOHTMAH
KOH/IPATMAH/ f t tTMAH
EDPTMAH TMAH/surfactant
EDP
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Variation in etching profile on (110) silicon wafer
Groove Wall OrientationsGroove Wall Orientations(111) (111) (100) (110)
KOHTMAHEDP
KOHTMAHEDP
KOHTMAH
KOH/IPATMAH/surfactantEDPEDP EDP EDP
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Non-conventional 3-D microstructures using KOH anisotropic etching
Etching from both sides of a wafer Two step etching using two mask layers Etching from both sides of a wafer Two-step etching using two mask layers
K. Sato, et al, Proc. IFToMM Intl. Micromechanism Symp. (Tokyo, 1993.6) 155-160
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Densely Arrayed Silicon Needles with a Pitch Distance of 200 microns Aiming at Transdermal Drug Delivery
M Shikida et al :Proc MEMS 03 (Kyoto 2003) 562M. Shikida et al.:Proc. MEMS-03 (Kyoto, 2003), 562
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
New types of anisotropically etched 3-D structures: Curved, Sharp-cornered, 45-degree-angled V-grooves
Prem Pal: Jpn. J. Appl. Phys. 49 (2010)056702
[ ][100]
[110]
[110]
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Anisotropic chemical etching of Sifrom MEMS Point of View
• Etching SolutionsKOH, “TMAH”, “EDP”, N2H4, NaOH, CsOH, etc.
Ch i l ti• Chemical reactionSi + 2OH- + 2H2O
Si(OH) + H SiO (OH) 2 + 2H→ Si(OH)4 + H2 → SiO2(OH)22- + 2H2
• What are known;Si (111) shows an extremely low etch rateSi (111) shows an extremely low etch rate.Etch-stop techniques: B-dope, Electro-chemical,
etc.etc.• Applications
Diaphragms, V-grooves, CantileversDiaphragms, V grooves, Cantilevers ---Limitations in fabricated shapes
Many mysteriesBasic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Many mysteries
Sequential reactions of Si etching in alkaline solution
Si + 2OH- + 2H2O → SiO2(OH)22- + 2H2
f fThis is the results of the following steps.(R. A. Wind, M.A. Hines, Surface Science 460 (2000) 21-38)
=SiH2 + OH- + H2O → =SiHOH+ H2 + OH-2 2 2
=SiHOH + OH- + H2O → =Si(OH)2+ H2 + OH-
( Si) Si(OH) 2H O 2( Si H) Si(OH)(≡Si)2=Si(OH)2 + 2H2O → 2(=Si-H)+Si(OH)4
Si(OH)4 + 2OH- → =SiO2 (OH)22-+ 2H2 O( )4 2 ( )2 2
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Contents
Characterization of Anisotropic EtchingCharacterization of Anisotropic Etchingin macroscopic domains
“Dangling-Bond Model” does not tell the truth,because no dynamics included. y
“Step Flow Model” explains anisotropy in the vicinity of Si (111)vicinity of Si (111)
*R d i t b t KOH d TMAH*Reversed anisotropy between KOH and TMAH*Etched shape clearly reflects atomic-step p y p
behavior in the vicinity of Si (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Contents
Characterization of Anisotropic EtchingCharacterization of Anisotropic Etchingin macroscopic domains
“D li B d M d l” d t t ll th t th“Dangling-Bond Model” does not tell the truth,because no dynamics included.
“Step Flow Model” explains anisotropy in the vicinity of Si (111) c ty o S ( )
*Reversed anisotropy between KOH and TMAH*Reversed anisotropy between KOH and TMAH*Etched shape clearly reflects atomic-step
behavior in the vicinity of Si (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Etching rate measurementK. Sato et al.: Sensors and Actuators A-64 (1998) 87-93.
(110) contact probe(110) contact probe
R = 22 mmprobing network
R 22 mm
R
(001)( )
(110)-
Hemispherical specimen of single-crystal silicon
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Hemispherical specimen
Before After
• Maximum etching depth: 100 - 150 µm
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Etching rate contour map for a KOH solution
(100)K. Sato et al.: Sensors and Actuators A-64 (1998) 87-93.
90゜ (111)(100)
60゜(110)
30゜
0゜
0゜
30
(110) 90゜
0゜0゜ 30゜ 60゜ 90゜
(100)NAGOYA UNIVERSITY
(100) min max
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Effects of a surfactant added to TMAH solutionK. Sato et al.: Sensors and Materials 13-5 (2001) 285-291.
90°
(010)
(110)90°
(010)
(110)(111)
60°
(110)
60°
(110)
30° 30°
0°0° 30° 60° 90°
(100)(001)
0°0° 30° 60° 90°
(100)(001)0 30 60 90(001) 0 30 60 90(001)
min max
25%TMAH + NCW 25%TMAH
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Poly-oxiethylene-alkyl-phenyl-ether
C9H19 O(CH2CH2O) HC9H19 O(CH2CH2O)nH
Hydrophobic HydrophilicHydrophobic Hydrophilic
• Liquid easy to operate with little foamingS bl b h i id d lk li l i• Stable both in acid and alkaline solutions
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Orientation-dependent effects of surfactant decreasing etch rates of silicon
2.500}2.000
2.500
25%TMAH (without surfactant)k}
/{10
0}
1.500
of {
i j k
1.000 25%TMAH+2%NCW
te ra
tio o
0.500
Etch
rat
0.000{100} {310} {210} {530} {320} {540} {110} {331} {221} {111} {211} {311} {100}
OrientationsOrientations
K. Sato, et al., Sensors and Materials 13-5 (2001) 285-291.
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Mask-corner undercut suppression
Effects of the surfactant NCWK. Sato, et al., Sensors and Materials 13-5 (2001) 285-291.
Orientations appearing on a vertex:(111) - ( j j 1 ) - (110)
25 wt.% TMAH, 80 ºCEtching depth: 50 µm
without NCW{111}
{100}
i h{110}
{110}
with 2 wt.% NCW
300Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
300 µm
Comparison of Structure Shape Etched from Same Mask Apertures
<110>
<110>
Prem Pal, J. Micromech. Microeng. 17 (2007) 2299–2307
Etch depth = 35 μm<110>
( ) (b) ( ) (d)(a) (b) (c) (d)
Pure 25 wt% TMAH
(a) (b) (c) (d)
T-Shaped cantilever
Circular island
Cross island
Cross aperture
25 wt% TMAH + NC-200
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
cantilever island island aperture
Etching ratedatabase
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Anisotropic etching simulation system MICROCAD
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Simulation results using MICROCAD
K Sato et al Electronics and Communications in Japan Part2 83 4 (2000)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
K. Sato, et al., Electronics and Communications in Japan, Part2, 83-4 (2000).
Simulation results using MICROCAD
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Simulation results using MICROCAD
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Densely Arrayed Silicon Needles with a Pitch Distance of 200 microns for Transdermal Drug Delivery
M. Shikida et al. Sensors and Actuators A 116 (2004) 264–271
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Arrayed Needle Fabrication Process:Combination of mechanical dicing and wet etching
M. Shikida et al. J. Micromech. Microeng. 14 (2004) 1462–1467
Etching time: (a) 0 min. (b) 10 min. (c) 20 min.
(d) 30 i ( ) 40 iBasic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
(d) 30 min. (e) 40 min.
MICROCAD Simulation Results.Etching time: (a) 0 min., (b) 5 min., (c) 10 min.,
(d) 15 min., (e) 20 min., (f) 25 min.Et hi diti 34 0 t % KOH 80oC
(a) (b) (c)
Etching conditions: 34.0 wt.% KOH, 80oC
(a) (b) (c)
(d) (e) (f)
M Shikida et al J Micromech Microeng 14 (2004) 1462 1467
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
M. Shikida, et al, J. Micromech. Microeng. 14 (2004) 1462–1467
Etched deep grooves on (110) Si using a KOH water solution
Groove depth: 90 microns
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
KOH and TMAH show different types of anisotropy
K. Sato, et al.: Sensors and Actuators A-73 (1999) 131-137.
TMAH: 25%, 90°C KOH: 40%, 90°C
90゜90°(010)
60゜60°(430)(110)
30゜30°
(011)
0゜0° (100) 00゜ 30゜ 60゜ 90゜
00° 30° 60° 90°(001) (101)
( 00)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Relation between the etching rate distribution and etched profile
Etching rate distribution
1 0
1.51.0
m/m
in)
m/m
in)
0.5
1.0
0.5
Etc
h ra
te (µ
m
Etc
h ra
te (µ
m
-90° 90°0°0
(111) (111)(110)-90° 90°0°0
(111) (111)(110)(311) (311)
(111)
Etch rate vectorEtched profile analyzed using Wulff-Jaccodine method
(110)
Si
25% TMAH (86°C) 40% KOH (70°C)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Contents
Characterization of Anisotropic EtchingCharacterization of Anisotropic Etchingin macroscopic domains
“D li B d M d l” d t t ll th t th“Dangling-Bond Model” does not tell the truth,because no dynamics included.
“Step Flow Model” explains anisotropy in the vicinity of Si (111)c ty o S ( )
*Reversed anisotropy between KOH and TMAH*Reversed anisotropy between KOH and TMAH*Etched shape clearly reflects atomic-step
behavior in the vicinity of Si (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Conventional Explanation of Anisotropy in Etching
Hypothesis: Number of dangling bond appearing on the silicon surface determines the etching ratesilicon surface determines the etching rate
zz
zxy x y
(100)面(110)面
Dangling bond:2Dangling bond:1 +(2)( d b k b d )
xy
Dangling bond:2Back bond:2
(Exposed back bond:2)Back bond:3
(111)面Dangling bond:1Back bond:3
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Step Flow Model for (111) SiliconM. Elwenspoek, J. Electrochem. Soc. 140-7 (1993) 2075-80
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Two types of stable steps on Si (111) surface(Mono-hydride and Di-hydride steps)
M A Gosalvez et al J Micromech Microeng 17 (2007) S1 S26
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
M.A. Gosalvez, et al. J. Micromech. Microeng. 17 (2007) S1–S26
Step movements determine profiles ofpits and mesa on (111) silicon surface
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Atomic level etching simulation in the vicinity of Si (111)
(111)(110)
M.A. Gosalvez, et al. J. Micromech. Microeng. 17 (2007) S1–S26
(111) (001)(110) →←
Pit-nucleation and Step-propagation
100 nm
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Our concern
I th t i l t fl d l• Is the atomic scale step flow model applicable to macroscopic etching?pp p g
Etching solutions: KOH, TMAHEt hi d th t f i tEtching depth: tens of micrometers
• Does the number of dangling bonds determine the activeness of the surfaces ordetermine the activeness of the surfaces or steps?
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Contents
Characterization of Anisotropic Etchingp gin macroscopic domains
“Dangling Bond Model” does not tell the truthDangling-Bond Model does not tell the truth,because no dynamics included.
“Step Flow Model” explains anisotropy in the vicinity of Si (111) y ( )
*Reversed anisotropy between KOH and TMAHReversed anisotropy between KOH and TMAH*Etched shape clearly reflects atomic-step
b h i i th i i it f Si (111)behavior in the vicinity of Si (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Etch Pit Growth on (111) Silicon.
Growth of individual pit traced during TMAH etching
K. Sato, et al.: Sensors and Materials 15-2 (2003) 93-99.
Growth of individual pit traced during TMAH etching.
10分後
Optical microscope images with time increments
・Wafer preparation… Oxidization 20分後 30分後p p
for 20 hours (3μm thick oxide) followed by oxide removal using HF.
20分後 30分後
・etching condition…25%TMAH, 80°30min
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
AFM image at the center of a pit etched with TMAH solution
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Comparison in the shape of etch pits between KOH and TMAH
25%TMAH 80℃30分40%KOH 70℃30分[1 1 2][ 1 1 2]
K. Sato, et al.: Sensors and Materials 15-2 (2003)
[1 1-2][-1-1 2] [-1-1 2] [1 1-2]
Top View
100μmView
0.00
0.25
0.50
m)
m)
-0 4
-0.2
0.0
0.2
0.4
0.6
Cross-Section
0 75
-0.50
-0.25
tch p
it d
ept
h (
オm
Etching time: 10 min
Etching time: 20 min
Etching time: 30 min
Etc
h p
it d
epth
(オ
m
-1.4
-1.2
-1.0
-0.8
-0.6
0.4
Etching time: 10 min
Etching time: 20 min
0.250.200.150.100.050.00-1.25
-1.00
-0.75Et E
0.40.30.20.10.0-2.4
-2.2
-2.0
-1.8
-1.6 Etching time: 20 min
Etching time: 30 min
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Distance (mm) Distance (mm)
Step movements determine profiles ofpits and mesa on (111) silicon surface
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Differently oriented etch pit growth governed by the difference in activated step
TMAHKOH TMAH
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Difference in Etching Rate Contour Map between KOH and TMAH
(010)(010)90゜
(010)
(110)(111) 90゜
(010)
(110)(111)
60゜
(011)
60゜
30゜
(100)(001)
30゜
(100)(001)
0゜
0゜ 30゜ 60゜ 90゜
(100)
(101)
0゜0゜ 30゜ 60゜ 90゜
(100)
(101)
KOH40%70℃ TMAH25%80℃KOH40%70℃ TMAH25%80℃
min maxKOH: Etch rate sharply increases by misorientation toward [1 1-2]
TMAH: Etch rate sharply increases by misorientation toward [-1-1 2]
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Contents
Characterization of Anisotropic Etchingin macroscopic domains
“Dangling-Bond Model” does not tell the truthDangling Bond Model does not tell the truth,because no dynamics included.
“St Fl M d l” l i i t i th“Step Flow Model” explains anisotropy in the vicinity of Si (111)
*Reversed anisotropy between KOH and TMAHReversed anisotropy between KOH and TMAH*Etched shape clearly reflects atomic-step
behavior in the vicinity of Si (111)behavior in the vicinity of Si (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Step Flow Model for (111) Silicon M. Elwenspoek, J. Electrochem. Soc. 140-7 (1993) 2075-80
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Difference in surface structure depending on a direction of deviation from silicon (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Etched deep grooves on (110) Si using a KOH water solution
Groove depth: 90 microns
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Asymmetric increase in etching rate by angular deviation from (111) orientation
(-11-1)
(110)
(-11-1)
(-112)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Step movements determine profiles ofpits and mesa on (111) silicon surface
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Answers to the questions
• Is the atomic scale step flow model applicable to macroscopic etching?to macroscopic etching?
YES, in the vicinity of (111)
Does the number of dangling bond determine• Does the number of dangling bond determine the activeness of the surfaces or steps?
NO(neither of the surface nor of steps)(neither of the surface, nor of steps)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Contents
Characterization of Anisotropic EtchingCharacterization of Anisotropic Etchingin macroscopic domains
“D li B d M d l” d t t ll th t th“Dangling-Bond Model” does not tell the truth,because no dynamics included.
“Step Flow Model” explains anisotropy in the vicinity of Si (111) c ty o S ( )
*Reversed anisotropy between KOH and TMAH*Reversed anisotropy between KOH and TMAH*Etched shape clearly reflects atomic-step
behavior in the vicinity of Si (111)
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
ReferencesEtch mechanisms and characterizationR.A. Wind and M.A. Hines, Surface Science 460 (2000) 21-38.M. Elwenspoek, J. Electrochem. Soc. 140-7 (1993) 2075-80.p , ( )M.A. Gosalvez, et al., J. Micromech. Microeng. 17 (2007) S1–S26.K. Sato, et al., Sensors and Actuators A-64 (1998) 87-93.K. Sato, et al., Sensors and Actuators A-73 (1999) 131-137.K. Sato, et al., Sensors and Materials 15-2 (2003) 93-99.
Effects of surfactantK. Sato, et al., Sensors and Materials 13-5 (2001) 285-291.Prem Pal, J. Micromech. Microeng. 17 (2007) 2299–2307.Prem Pal, et al, J. MEMS 18-6 (2009) 1345-1356.M.A. Gosalvez, et al., J. Micromech. and Microeng. 19-12 (2009) #125011.P P l t l J J A l Ph 49 (2010) 056702Prem Pal, et al., Jpn. J. Appl. Phys. 49 (2010) 056702.
Needle ArrayM. Shikida, et al., Proc. MEMS-03 (Kyoto, 2003), 562-565. M Shikida et al Sensors and Act ators A 116 (2004) 264 271M. Shikida, et al., Sensors and Actuators A 116 (2004) 264–271.M. Shikida, et al, J. Micromech. Microeng. 14 (2004) 1462–1467
Simulation systemK Sato et al Proc IFToMM Intl Micromechanism Symp (Tokyo 1993 6) 155 160K. Sato, et al, Proc. IFToMM Intl. Micromechanism Symp. (Tokyo, 1993.6) 155-160.K. Sato, et al., Electronics and Communications in Japan, Part2, 83-4 (2000). This
publication was translated from Trans. of the Inst. of Electronics, Information and Communication Engineers C-II J82-C-II no 3 (1999) 84-91
Basic 2 Anisotropic Wet-etching of Silicon: Prof. K. SatoCharacterization and Modeling of Changeable AnisotropyCOE for Education and Research of Micro-Nano Mechatronics, Nagoya University
Communication Engineers C II, J82 C II, no. 3 (1999) 84 91.