TLS / OBIRCH / TIVA
TLS / OBIRCH / TIVA
TLS / OBIRCH / TIVA
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MICROELECTRONICS<br />
THALES Microelectronics S.A.<br />
FAILURE ANALYSIS LABORATORY<br />
THERMAL LASER STIMULATION<br />
(<strong>TLS</strong> / <strong>OBIRCH</strong> / <strong>TIVA</strong>)
I.C. FA flow<br />
Electrical<br />
MICROELECTRONICS<br />
diagnostic<br />
Defect<br />
localization<br />
Physical<br />
analysis<br />
<strong>TLS</strong> in the FA flow<br />
Current related defects<br />
Emission<br />
microscopy<br />
– I leakage junctions<br />
– I leakage oxides<br />
Thermal Laser<br />
Stimulation<br />
– I leakage metallic<br />
shorts<br />
2
MICROELECTRONICS<br />
LASER<br />
λ = 1,3 µm<br />
<strong>TLS</strong> Principles<br />
• Heating<br />
High absorption in:<br />
– Metals<br />
– Polysilicon<br />
• No e-h pair<br />
generation<br />
– Highly doped silicon<br />
α<br />
Aluminium<br />
=<br />
Conduction band<br />
E photon < E b.g.<br />
Valence band<br />
1,<br />
1x10<br />
6<br />
cm<br />
−1<br />
3
MICROELECTRONICS<br />
Laser Heating of Metals<br />
Electric current density :<br />
j ≅ σ<br />
E<br />
[ + Q( − ∇T<br />
) ]<br />
↑ T ° → Current variation<br />
∇ T ° → Additional current<br />
4
MICROELECTRONICS<br />
A. Resistance Variation<br />
ρ L<br />
∆ = 0 α 2δ<br />
S<br />
TCR<br />
( − ) ∆T<br />
R T<br />
Aluminium<br />
α TCR = 4,29x10 -3<br />
α TCR → Temperature<br />
Coefficient of Resistivity<br />
δ T → Coefficient of<br />
Thermal linear dilatation<br />
Current Source (<strong>TIVA</strong>)<br />
∆V<br />
= ∆R<br />
⋅<br />
Voltage Source (<strong>OBIRCH</strong>)<br />
δ = 2,36x10 T -5 ( ∆I<br />
= − ∆R<br />
R<br />
2<br />
)V<br />
I<br />
5
B. Electromotive Force Generation<br />
MICROELECTRONICS<br />
T > T 0<br />
Laser<br />
T 0 M 1 M 2<br />
12<br />
Q → Thermoelectric power or<br />
Seebeck coefficient<br />
T 0<br />
( Q Q )( T T ) Q ( T T )<br />
V = − − = −<br />
1<br />
2<br />
12<br />
Q 12 → Relative Thermoelectric power<br />
0<br />
0<br />
Materials Q 12 (µV/ o C)<br />
Al / W 7,0<br />
Al / n+ Poly<br />
Al / n+ Si<br />
(10 20 cm -3 )<br />
-121<br />
-105<br />
6
Parameters:<br />
T ini : 25 o C<br />
P laser : 100mW<br />
R laser : 0,65µm<br />
V fast :1,23m/s<br />
V slow : 0,00768m/s<br />
MICROELECTRONICS<br />
<strong>TLS</strong> Model<br />
SiO 2<br />
1µm<br />
Al<br />
Silicon<br />
10µm<br />
1µm<br />
0.5µm<br />
1µm<br />
4µm<br />
Model: 1µm Al line, Gaussien Laser<br />
2 cases:<br />
- Transversal<br />
- Longitudinal<br />
Length = 120µm<br />
7
MICROELECTRONICS<br />
A. Transversal Case<br />
• Rapid thermal equilibrium and heat dissipation<br />
• Hottest temperature occurs at laser spot<br />
Slowest scanning speed<br />
T (°C)<br />
75<br />
65<br />
55<br />
45<br />
35<br />
25<br />
transversal slow<br />
transversal fast<br />
0 1 2 3 4 5 6 7 8 9 101112 13<br />
Position (µm) Elapsed time (µs)<br />
8
MICROELECTRONICS<br />
B. Longitudinal Case<br />
• Thermal equilibrium reached after 10µs<br />
Slowest scanning speed<br />
T (°C)<br />
75<br />
65<br />
55<br />
45<br />
35<br />
25<br />
longitudinal slow<br />
longitudinal fast<br />
0,0E+00 5,0E-06 1,0E-05 1,5E-05 2,0E-05<br />
Time (s)<br />
9
trans. slow<br />
trans. fast<br />
long. slow<br />
long. fast<br />
MICROELECTRONICS<br />
Temperature Calculation<br />
75<br />
65<br />
55<br />
45<br />
35<br />
25<br />
T (°C)<br />
-20 -10 0 10 20<br />
Position from the laser center (µm)<br />
At thermal<br />
equilibrium:<br />
Thermal spreading<br />
limited to ~ 30µm<br />
Temperature varies<br />
linearly with laser<br />
power<br />
∆T max = 0.55 o C/mW<br />
10
Resistance Variation (Ω)<br />
0,20<br />
0,15<br />
0,10<br />
0,05<br />
0,00<br />
MICROELECTRONICS<br />
Resistance Calculation<br />
∆R = 0,17Ω<br />
0 20 40 60 80 100<br />
Laser Power(mW)<br />
∆R max = 1,7 mΩ/mW<br />
ρ α<br />
∆R<br />
=<br />
−<br />
L 0 TCR T T<br />
S<br />
( )<br />
Moy 0<br />
11
MICROELECTRONICS<br />
Model Conclusion<br />
Localization of defects and lines submitted to I leakage<br />
∆R 1/∝ Section<br />
∆V ∝ I leakage<br />
Localization of junctions and interface defects<br />
Q 12 or ∆T<br />
Precise localization<br />
Thermal diffusion < 30µm<br />
T max at center of line and laser beam<br />
12
MICROELECTRONICS<br />
<strong>TLS</strong> System Requirements<br />
• Laser scanning microscope (LSM)<br />
– Gaussian laser of λ >1,1µm<br />
• Acquisition and imaging system<br />
• Biasing and amplification scheme :<br />
Techniques Inventor Bias<br />
<strong>OBIRCH</strong><br />
CC-<strong>OBIRCH</strong><br />
<strong>TIVA</strong><br />
TBIP<br />
XIVA<br />
Nikawa<br />
Nikawa<br />
Cole<br />
Palaniappan<br />
Falk<br />
SEI Cole<br />
V<br />
I<br />
V<br />
I / None<br />
Amplifier<br />
I<br />
V<br />
V<br />
V<br />
<strong>TLS</strong><br />
13
<strong>OBIRCH</strong><br />
<strong>TIVA</strong><br />
MICROELECTRONICS<br />
I.C.<br />
I.C.<br />
Configurations<br />
AMPLI<br />
I / V<br />
AMPLI<br />
V / V<br />
I.C.<br />
AMPLI<br />
V / V<br />
• Other configurations:<br />
– Inductance (TBIP / XIVA)<br />
– No bias (SEI)<br />
14
Poly line<br />
MICROELECTRONICS<br />
<strong>TLS</strong> on Test Structures<br />
Al line<br />
N+ resistance<br />
No bias (SEI)<br />
15
• Failed CMOS IC<br />
– I ~ 2mA @ 5V<br />
• No emission<br />
• Front-side<br />
MICROELECTRONICS<br />
<strong>TLS</strong> 5X<br />
<strong>TLS</strong> Case Study #1<br />
<strong>TLS</strong> 200X<br />
Metal short<br />
(M1-M2)<br />
16
• Failed BICMOS IC<br />
– I > 100 µA(I/O)<br />
• Backside<br />
– 4 metal levels<br />
MICROELECTRONICS<br />
EMMI (20x)<br />
<strong>TLS</strong> Case Study #2<br />
<strong>TLS</strong> (20x)<br />
W short<br />
(Drain-Source)<br />
17
• Failed CMOS IC<br />
– I ~ 2 mA @ 3V<br />
• Front-side<br />
MICROELECTRONICS<br />
<strong>TLS</strong> (20x)<br />
<strong>TLS</strong> Case Study #3<br />
<strong>TLS</strong> (20x)<br />
Metal short<br />
(M2-M3)<br />
18
MICROELECTRONICS<br />
<strong>TLS</strong> Case Study #4<br />
• ESD failed commercial ICs<br />
– HBM and MM stressed<br />
• Front-side<br />
– No bias applied (SEI)<br />
SEI (200x)<br />
Molten Si/Al<br />
filament<br />
Molten Si<br />
spike<br />
SEI (50x)<br />
19
• GaAs failed ASICS<br />
– I ~ 50 µA@ 3V<br />
• Front-side<br />
MICROELECTRONICS<br />
<strong>TLS</strong> (100x)<br />
<strong>TLS</strong> Case Study #5<br />
Defects induced by<br />
CDM type ESD stress<br />
Gold filament<br />
20
Conclusion : <strong>TLS</strong> Application Field<br />
Thermal<br />
Laser<br />
Stimulation<br />
Bias<br />
No Bias<br />
MICROELECTRONICS<br />
Signature Defect type Material<br />
Ileakage >1µA<br />
All circuits<br />
Comparison<br />
Current lines<br />
Shorts<br />
ESD defects<br />
Voids<br />
ESD defects<br />
Interface<br />
defects<br />
AI, W, Au,<br />
PolySi,<br />
Doped Si,<br />
Amorph. Si<br />
Metal / Metal<br />
Metal / Si<br />
Metal / Poly Si<br />
Melted Si / Si<br />
21
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