Transcript Reliability Laboratory

Presentation
on
Setting up Reliability Laboratory
Presented
by
Dr. G.H. Massiha
Department of Industrial Technology
University of Louisiana, Lafayette
Topics

Need for setting up Reliability Laboratory
 Reliability issues in Metal thin Films.
 Reliability Problems.
 Electromigration Measurement Techniques.
 Excess Noise Measurement.
 1/f Noise Phenomenon.
 Presence of 1/f Noise.
 Measurement System And Technique.
 Experimental Set-up
 Diagrams of the samples used.
 Results
 Concluding Remarks
Need for setting up Reliability
Laboratory

One of the research lab in Department of Industrial
Technology, University of Louisiana at Lafayette provides
facility for students to study reliability issues in metal thin
films.
 Students will learn new techniques to measure excess noise
in the metal thin film.
 This hands on experience will make students well prepared
to handle challenges in the various research labs, on
joining industry.

Website at: http://www.ucs.louisiana.edu/~ghm2469
Reliability issues in Metal Thin films

Metal Thin Films should maintain
Structural integrity.
 In Metal thin films structures chemical
reaction or inter diffusion appears in small
scale at room temperature.
 Tighter constraints are placed on film
material and dimensions.
Reliability Problems

The decrease in the thin film dimension has
caused a rise in the current density.
 The failure mechanisms encountered in VLSI,
metallization defects form the 20 –30%.
 Metallization Defects:




Electromigration – Most prominent device failure mode.
Aluminum Micro-cracks
Contact Alloying Problems
Bonding Problems
SEM Picture of Damaged Al Film
Electromigration Measurement
Techniques

Measurement of mass accumulation and Depletion.


The Median Time Failure Measurement(MTF)


Needs special Design samples, expensive experiment setup.
Needs large number of identically and fabricated samples.
Resistance Measurement

It is difficult to assume that the electromigration is the only source
of resistance change.
– Also, a long period of test time is needed and the test
samples usually are not reusable for repeating electromigration tests.
Excess Noise Measurement





Have close links to the electromigration damage in
the thin films.
Magnitude of excess noise is very sensitive to its
electromigration damage.
Short period of time needed for noise
measurements.
Non-destructive nature.
Ideal tool for studying electromigration in thin
films.
1/f Noise Phenomenon
1/f0 white noise , shows a
fluctuation in which the power
changes at random, irrespective of
wave frequency.
 The 1/f2 Brownian noise, the
bottom curve, shows waves which
change in very strict conformity
with a certain fluctuation pattern.
 The 1/f, the middle line, indicates a
pattern in which the power change
is inversely proportional to the
frequency.
 The 1/f noise is less random then
White Noise and more random then
Brownian noise

Presence of 1/f Noise


It appears in widely different systems
such as radioactive decay, chemical
systems, biology, fluid dynamics,
astronomy, electronic devices, optical
systems, network traffic and economics.
Classical music and 1/f noise.
-- Frequency is inversely proportional to
the power, a relationship which creates
1/f fluctuations. The constant, rusty
noise of a TV after broadcasting ends is
displeasing. On the contrary, wave
patterns which are most soothing
conform to the 1/f fluctuation. The
sounds created by classical music
following a 1/f fluctuation patterns are
especially soothing to our ears.
Measurement system and
Techniques


An oscilloscope can be
used to see and measure a
voltage across a resistor
when direct current is
passed through the
conductor.
Using a very fine lens to
look at the voltage
configuration on the
oscilloscope screen, one
can see that the voltage
fluctuates with time.
Experimental setup

SR785-100 kHz Dual channel
Dynamic Signal Analyzer.
 EG&G Ultra Low-Noise
Voltage Preamplifier.
 SR715 LCR meter.
 DC Power Supply
 MultiMeter.
 Biasing Circuit
 Thermocouple
SEM Picture of The Sample
Layout of the Sample Used

2 set of three different
thin film resistances
 R1 = 75.7
 R2 = 63.12 
 R3 = 39.96 
R1
R2
R3
Resistance variation with
Temperature
Resistance V/S Temperature
Voltage (V)
Temp Deg C
R1
R2
140
R3
R1
none
5
7.5
10
12.5
15
17.5
20
23.5
24
27.7
30.5
38.5
42.5
51.6
58
75.7 63.12
78.85 64.46
86.67 73.28
91.83 78.13
98.49 85.67
107.68 93.27
114.51 99.1
121.6 103.58
39.96
47.94
51.35
59.31
73.63
81.02
90.24
98.15
Resistance
120
R2
100
80
R3
60
40
20
0
23.5
24
27.7
30.5
38.5
42.5
51.6
58
75.7
78.85
86.67
91.83
98.49
107.68
114.51
121.6
63.12
64.46
73.28
78.13
85.67
93.27
99.1
103.58
39.96
47.94
51.35
59.31
73.63
81.02
90.24
98.15
Temperature
A Typical One over f Noise

1/f Noise Spectrum
from 3 to 300 Hz.
Concluding Remarks






Noise measurement is a quick technique of understanding
characteristics of interconnects and provides with information about
reliability.
Students learn how to use Spectrum Analyzer to capture and analyze
signals generated by the change in the metal thin film resistance while
the film is biased and is under stress.
In addition Students learn the capability and usage of low noise
amplifier, thermocouple, and LCR meter.
Furthermore, students learn to design and build biasing and stressing
circuits.
In conclusion students working in this research laboratory would write
a technical paper to present the results obtained in various experiments
performed.
We hope students become prepared to the challenges of working in
various research laboratories when they join the industry.
Contributed By
Kuldeep S. Rawat
Graduate Student
Center for Advanced Computer Studies
Edie Lau
Undergraduate Student
Industrial Technology
University of Louisiana, Lafayette
This study is sponsored by the State of Louisiana Board of Regent
Contract No. LEQSF(1999-02)-RD-A-54