Reliability Laboratory

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Reliability Laboratory

• Presentation on
• Setting up Reliability Laboratory
• Presented
• by
• Dr. G.H. Massiha
• Department of Industrial Technology
• University of Louisiana, Lafayette

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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

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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
  

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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.

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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

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SEM Picture of Damaged Al Film
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Electromigration Measurement Techniques

• Measurement of mass accumulation and Depletion.
• Needs special Design samples, expensive
  experiment setup.
• The Median Time Failure Measurement(MTF)
• 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 electro-migration tests.

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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.

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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 

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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.
•  

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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.

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Experimental setup

• SR785-100 kHz Dual channel Dynamic Signal
  Analyzer.
• EGG Ultra Low-Noise Voltage Preamplifier.
• SR715 LCR meter.
• DC Power Supply
• MultiMeter.
• Biasing Circuit
• Thermocouple

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SEM Picture of The Sample
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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
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Resistance variation with Temperature
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A Typical One over f Noise

• 1/f Noise Spectrum from 3 to 300 Hz.

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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.

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Contributed ByKuldeep S. RawatGraduate
StudentCenter for Advanced Computer
StudiesEdie LauUndergraduate
StudentIndustrial TechnologyUniversity of
Louisiana, LafayetteThis study is sponsored by
the State of Louisiana Board of Regent Contract
No. LEQSF(1999-02)-RD-A-54