Study of MEMS Devices for Space
Applications
The 24th Microelectronics Workshop
October 2011
October,
Maya Kato
Electronic Devices and Materials Group
J
Japan
A
Aerospace
Exploration
E l ti A
Agency
1
Outline
 Introduction of MEMS
 Process
– Fabrication process
 Examples
– Data (Process)
– Sample devices made as an experiment
(Actuator, Switch and Mirror)
 Future activities
 Conclusions
・MEMS fabrication was supported by Nihon University(CST)
2
Introduction of MEMS
 MEMS: Micro Electro Mechanical System
 Advantages of MEMS Devices
– Downsizing
g and weight
g saving
g device
• For microfabrication applied by semiconductor process
• For integration of structure and electronic circuit
– Implementation of various functions
• For utilizing various physical phenomena such as mechanics,
electronics, optics, and fluid
– Low cost
• Similar to semiconductor process, MEMS can be mass
mass--produced
with good and stable quality
 Application of MEMS
– Sensor
ensor,, Actuator, Biotechnology, Information machines and
equipment, ・・・・
3
Application of MEMS
GMR sensor
(engine control)
microphone
（ communication ）
gyroscope
（position control ）
Biosensor
（ driver
driver's
s condition ）
infrared sensor
（tire pressure ）
acceleration
l
ti
sensor（airbag）
inclination sensor
i f
infrared
d sensor
AE sensor
crash sensor
（detection of abnormal sound）
infrared sensor
（infrared temperature sensor）
Introduction of MEMS
・ High-Density and High-Performance
・ Small and lightweight
・ Application of semiconductor process.
・ Very minute mechanical structure is
created on Si chip.
RF
Ci
Circuit
it
RF
Si chip
Sensor
Micromachine
I t
t d circuit
i it ＝
＋ Integrated
Micro
dynamo
Micro
Electro
Mechanical
System
New
Device
5
Fabrication Process
1. Starting
g material : ((SOI wafer))
2. Surface cleaning and HMDS
SiO2
Si (Device)
SiO2 (BOX)
Si (Handle)
3. Resist coating
Fig.1 Cross section
SiO2
4. Photolithography (Patterning)
(20mm□ Chip)
5. Etching
g (Surface:
(
SiO2 )
6. Resist removal
7. Si Deep RIE (Bosch process; ICP)
Acetone
A
Ethanol
...
SC1(NH4OH / H2O2 / H2O)
....
HMDS(Hexamethyldisilazane)
8. Release : BOX Layer (SiO2)
Fi 2 T
Fig.2
Top view
i
・ ICP: Inductively Coupled Plasma
・MEMS fabrication was supported by Nihon University(CST)
6
Fabrication Process
7. Si Deep RIE (Bosch process; ICP)
8. Release : BOX Layer(SiO2)
SiO2
Si (Device)
SiO2 (BOX)
Si (Handle)
Fig.7-1 Cross section
Fig.7-2
g
Top
p view
ICP
Release
Fig.8-1 Cross section
Fig 8-2
Fig.8
2 Top view
7
Example Data 【 Effect of HMDS 】
・ SiO2 Etching pattern
OFPR800LB酸化膜・HMDS処理効果
Effect of HMDS
（凸面） treatment
1.5
1
05
0.5
3 .8 6 5 2
3 .8 6 0 8
3 .8 5 6 4
3 .8 5 2 0
3 .8 4 7 6
3 .8 4 3 2
3 .8 3 8 8
-0.5
05
3 .8 3 4 4
0
3 .8 3 0 0
Without HMDS
(μ 2ｍ(µm
） m)
TS iO 2 膜 厚offさSiO
Thickness
Without HMDS
HMDS未処理
HMDS処理(10min.)
HMDS Coating (Vapor for 10 minutes )
位置(ｍｍ）
Location
(mm)
HMDS Coating (Vapor)
Sharp
・ HMDS: Hexamethyldisilazane [(CH3)3Si]2NH
8
Example Data 【 Si Deep RIE; ICP 】
S (Width)
・ Parameter: ((Depo
p – Etch)) Cycle
y
【 L & S 図1.1
TEG
】
図1
1 D-E条件（1-2
D E条件（1
2、サイクル数）のＳ幅による深さ依存
サイクル数）のＳ幅による深さ依存
◆ Depo - Etch = 1sec
2sec - 2sec
4sec
50.00
40.00
150cyc
150
100
50cyc
50
25cyc
25
深 さL（（μｍ）
μｍ）
L (Depth)
100cyc
30.00
20.00
10.00
0.00
0
10
20
30
SS幅(μｍ）
(μｍ））
S幅(
40
50
60
9
Example Data 【 Si Deep RIE; ICP 】
【 L & S TEG】
◆ Depo - Etch = 1sec - 2sec
SEM images
25cyc
S= 3um
S
S= 5um
S
S= 7um
S
S= 10um
S
50cyc
100cyc
10
Example Data 【 Si Deep RIE; ICP 】
【 L & S TEG】
◆ Depo - Etch = 1sec - 2sec
Cross section
25cyc
S= 3um
S
S= 5um
S
S= 7um
S
S= 10um
S
50cyc
100cyc
11
Example Data 【 Si Deep RIE; ICP 】
ＳｉＯ２
Ｓｉ
deficient etching
Moderate ecching
notch
Over etching
12
Example Data 【 Residual material 】
SEM and EPMA images
(after BOX Layer etched)
SEM
Si
F
C
R id l material
Residual
t i l
C4F8
(protection
generation film
at ICP)
Al
Au
13
Example Device (1) 【 MEMS
MEMS--Actuator 】
 Structure
Suspension
p
Device Layer = 35um
BOX Layer = 4um
GND
+V
14
Example Device (1) 【 MEMS
MEMS--Actuator 】
 Characteristic
【 Voltage vs Stroke 】
Stroke (um)
Parameter: (Suspension [ Width – Length ])
25
20
5um - 500um
6um - 300um
6um - 400um
6um - 500um
7um - 300um
7um - 400um
15
10
110
100
90
80
70
60
50
40
30
20
10
0
0
5
Voltage (V)
15
Example Devices (2)
 MEMS
MEMS--Switch
 MEMS
MEMS--Mirror
・ Vertical structural type
Device Layer
y = 60um
BOX Layer = 4um
◆ Impact
p
test ((at 644G,z-axis)
,
)
◆ Opening-and-closing examination
( >100 million times )
16
Future activities
 Examination
– Phenomena peculiar to MEMS, such as “stiction”.
– Improvement
p
of manufacturing
g technology.
gy
– Ensuring high reliability and evaluation toward space
applications.
 Future
– Manufacturing of MEMS
MEMS--Shutter using actuator.
– Research and development of RF
RF--Switch
Switch..
・Space components are required to have high quality.
– Others;; Evaluation of commercial MEMS components
p
toward space applications.
17
MEMS--Shutter
MEMS
 Useful as a tool for the optical / radiation examination on
the ground.
Shutter cover
Light / Radiation
Actuator
Si ((Device):
) 35～50um
SiO2(BOX): 2～4um
Through
Th
h hole
h l
20～30um
Si (Handle) 150～250um
Test
Sample
18
RF--Switch
RF
 Useful for switches
switches, such as “Synthetic
Synthetic Aperture Radar”
Radar .
◆
Environment / Requirement
High reliability ----- life, Failure, Operational stability
Radiation
Vibration and shock (Launch)
Temperature ----- High, Low, Cycle
Practicality -------- Small and lightweight, Quantity yield, Low cost
・・・・
19
Roadmap
FY2010
【Design and Fabrication】
Basic technology
gy
in
in JAXA
◆ Application to devices
MEMS-Shutter etc.
(for an Optics / Radiation test)
FY2011
FY2012
Standardization
Technical extension / Application
pp
expansion
p
TEG
Fabrication, Examination, Evaluation
Test use
R
h off reliability
li bilit and
d ttechnical
h i l subjects
bj t
◆ Research
Research,
Examination
･･･→ RF-Switch
(for missions, for control, etc. )
【Commercial Parts】
【
】
for space application
Fabrication of TEG
(for reliability assessment)
Solution
Device
development
of
technical
subjects
Solution of technical subjects
(turned to space application)
Standardization
Examination and Evaluation
◆ Gyroscope
FY2014～
FY2013
Use
use in space
(Data source for an FPGA actual proof)in
Space
Measurement of the characteristic
Environment / Radiation examination
Environmental test
TAG202, etc.
◆ New device for application
Research,
Examination
RF-Switch, etc.
Test use
Environment / Radiation examination
space application
【Related elements / Means】
Nihon University
(support)
Institute of Space and Astronautical Science (ISAS)
(Cooperation)
External organization
new external organization
(Equipment and technology)
Enhancing examination / evaluation equipments
20
Conclusions
 Design / Fabrication environment of fundamental MEMS
was acquired.
– Micro fabrication process technology with a minimum width of
3um (TEG pattern) was acquired
acquired.
– The electrostatic type actuator was manufactured and the
characteristic was acquired.
– Technology was applied and other devices were made as an
experiment.
 Future
– Make an useful MEMS shutter as an experiment to a terrestrial
examination (radiation and optics).
– Study the failure mechanism and reliability peculiar to MEMS such
as “stiction”.
stiction .
– Promote research and development of RF-Switch based on the
results.
21
Thank you for your attention
22