MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
RF-MEMS activities in Micronova
Mika Koskenvuori
[email protected] Research Institute
Research Highlights Seminar3.12.2004 Micronova – Helsinki University of Technology
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
What is MEMS?
MEMS = MicroElectroMechanicalSystem
Use fabrication methods learned from the IC-processing to fabricate (3D)mechanical structures
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Outline
• Introduction and motivation• MEMS-based reference oscillator• Stability-issues• IC-electronics• Conclusions
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Outline
• Introduction and motivation• MEMS-based reference oscillator• Stability-issues• IC-electronics• Conclusions
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Introduction
Motivation – Why MEMS?
Small size
Photo: Jyrki Kiihamäki
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Introduction
Motivation – Why MEMS?
Good performance•Low losses•Low power consumption•High stability
-10
-5
0
5
10
15
14758500 14758750 14759000 14759250 14759500 14759750 14760000Frequency [Hz]
S 21 [
dB
]
-140
-120
-100
-80
-60
-40
-20
0
20
Ph
ase
[Deg
85 Hz
3 dBQ=180 000
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Introduction
Motivation – Why MEMS?
Utilizes “standard” IC-manufacturing processes:•Mass production•Low price•Possibility to integrate
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Introduction
Motivation
Source: http://www.inside-gsm.com
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
• Motivation• MEMS-based reference oscillator• Stability-issues• IC-electronics• Conclusions
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
Scaling
sizefr
1∝ fr ~ 1 GHzfr ~ 1 kHz fr ~ 100 kHz fr ~ 10 MHz
L~
10 c
m L~
1 m
m
L~
10 µ
m
L~
100
nm
MEMS NEMS
now future
• Typically coupling gets weaker as size is reduced• Dissipations are increased by reducing the size
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
Specifications
• High stability• Aging < 1ppm/year
• Low noise• Phase noise
• -130 dBc/Hz@1kHz• Noise to carrier
• -150 dBc/Hz-150dBc/Hz-130dBc/Hz
1kHz
1/fm3
1/fm1
L(fm)
fm0
1/fm0
SSB Phase Noise Spectrum
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Outline
• Motivation• MEMS-based reference oscillator• Stability-issues• IC-electronics• Conclusions
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Long-term stability - Encapsulation process
Encapsulated sample
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Long-term stability - Results Long-term stability - Results
Stability of resonance frequency:Vacuum encapsulated vs. open samples ( > 1 month)
0 200 400 600 800 1000-80
-70
-60
-50
-40
-30
-20
-10
0
10
0 200 400 600 800 10000
5
10
15
20
25
30
35
40
Time [h]
df/f
[ppm
] RH
[%]
Sample 1
Sample 2
Sample 3
Sample 4
Rel.Humidity
• All four samplesmeasuredsimultaneously
•Data temperaturecompensated
•Common bias-voltage (40V) on all the time
note correlation betweenRH and fr (open samples)
encapsulated samples
open samples
M. Koskenvuori et al. Sensors and Actuators A, 115 (2004)
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Long-term stability - Results Long-term stability - Results
Detailed analysis of the vacuum-encapsulated samples
0 200 400 600 800 1000-6
-5
-4
-3
-2
-1
0
1
2
0 200 400 600 800 100030
40
50
60
70
80
90
100
Time [h]
df/f
[ppm
] T [°C
]
Sample 1
Sample 2
Temperature
Temperature cycle 1+30K (duration 8h)
Temperature cycle 2+30K (duration 4h)
Power-off (reboot)- amplifier- bias
Devices taken outside the chamber
M. Koskenvuori et al. Sensors and Actuators A, 115 (2004)
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
• Motivation• MEMS-based reference oscillator• Stability-issues• IC-electronics• Conclusions
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
MEMS-resonator with IC-electronics
Vbias
buffer
In2
out
Out1
loop amplifier
VDD
gnd
In1
Gaincontrol
loop amplifier
Vbias
CPCP
out
buffer
CL = 10 pF
P. Rantakari et al. Transducers’05 (2005) - submitted
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
Simulated results
10-1 100 101 102 103 104 105 106
-140
-120
-100
-80
-60
-40
-20
fm [Hz]
SS
B p
hase
noi
se [d
Bc/
Hz]
P has e nois e a t gateP has e nois e a t output Design parameters:
Cp = 1pFro = 630kΩgm = 0.030 mSp = 117.5 ppm∆C = 18.5542 fFgm,buffer = 0.084 mSQL = 51040
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
MEMS-resonator
320 µm
Photo: Jyrki Kiihamäki
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
MEMS-resonator
12.93 12.931 12.932 12.933 12.934 12.935 12.936 12.937-30
-20
-10
0
10
20
30
Frequency [Hz]
S21
[dB
]
S 21
12.93 12.931 12.932 12.933 12.934 12.935 12.936 12.937
-150
-100
-50
0
Frequency [Hz]
Pha
se [D
egre
e]
20V
4V
[fF]560C0Stray capacitance[µA]150IMAXMaximum current
[mH]670LmMotional inductance[Ω]500RmMotional resistance[aF]230CmMotional capacitance[nm]180DTransducer gap
110 000Q0Unloaded Q-factor[MHz]12.933F0FrequencyUnitsValueSymbolParameter
[fF]560C0Stray capacitance[µA]150IMAXMaximum current
[mH]670LmMotional inductance[Ω]500RmMotional resistance[aF]230CmMotional capacitance[nm]180DTransducer gap
110 000Q0Unloaded Q-factor[MHz]12.933F0FrequencyUnitsValueSymbolParameter
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
IC-electronics
• STMicroelectronics process
–BiCMOS–0.25 µm–2.5 V
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
Loop-amplifier
1 0 5 1 0 6 1 0 7- 1 6 0
- 1 5 5
- 1 5 0
- 1 4 5
- 1 4 0
- 1 3 5
- 1 3 0
- 1 2 5
F r e q u e n c y [ H z ]
Noi
se [d
Bm
/Hz]
I n p u t R e d u c e d N o i s e o f d 5
1 . 51 . 61 . 71 . 81 . 92
1 0 3 1 0 4 1 0 5 1 0 6 1 0 7
- 2 0
- 1 0
0
1 0
2 0
3 0
4 0
F r e q u e n c y [ H z ]
Gai
n [d
B]
1 . 71 . 81 . 922 . 1
Frequency [Hz]
Gai
n [d
B]
Frequency [Hz]
Noi
se [d
Bm
/Hz]
24854992011087253
rout [kΩ]
29.9611.289272.250.929.8455.5208813.55.41.98.25141.046240161.85.88260.03318333.21.75.19393.0583138.555.41.64.43524.4184205.2582.11.5
Vn [nV/√ Hz]gm [uS]Pdc [uW]Idc [uA]Vb [V]
24854992011087253
rout [kΩ]
29.9611.289272.250.929.8455.5208813.55.41.98.25141.046240161.85.88260.03318333.21.75.19393.0583138.555.41.64.43524.4184205.2582.11.5
Vn [nV/√ Hz]gm [uS]Pdc [uW]Idc [uA]Vb [V]
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
MEMS-Based reference oscillator
MEMS-resonator with IC-electronics
P. Rantakari et al. Transducers’05 (2005) - submitted
-1000 -500 0 500 1000-150
-100
-50
0
Frequency[Hz]
PSD
[dB
m/H
z]
Agilent 89400 dynamic range: 120 dB
buffer noise
-1000 -500 0 500 1000-1000 -500 0 500 1000-150
-100
-50
0
-150
-100
-50
0
Frequency[Hz]
PSD
[dB
m/H
z]
Agilent 89400 dynamic range: 120 dB
buffer noise
Parameter Symbol Value UnitFrequency f 0 12.93 [MHz]Output level U out 300 [mVpp]
Power consumption P 240 [µW]Motional current i mot 25 [µA]Buffer noise V n 5.7 [nV/sqrt(Hz)]Noise floor C/N -144 [dBc/Hz]
MMICRONOVAICRONOVACentre for microCentre for micro-- and nanotechnologyand nanotechnology
Conclusion
Summary
• MEMS devices could offer an integrable alternative for discrete components in the future
• Stability of RF-MEMS devices was found to be sufficient for even GSM-specifications
• A micromechanical oscillator was demonstrated with MEMS-resonator and custom IC-electronics
•Low power consumption was demonstrated•Sufficient noise-floor was demonstrated•Sufficient phase-noise performance is expected