Reliability LaboratoryReliability Laboratory

Presentation on

Setting up Reliability Laboratory

Presented

by

Dr. G.H. Massiha

Department of Industrial Technology

University of Louisiana, Lafayette

TopicsTopics

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 Need for setting up Reliability LaboratoryLaboratory

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 filmsReliability 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 ProblemsReliability 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 FilmSEM Picture of Damaged Al Film

Electromigration Measurement Electromigration Measurement TechniquesTechniques

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.

Excess Noise MeasurementExcess 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 Phenomenon1/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 NoisePresence 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 Measurement system and TechniquesTechniques

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 setupExperimental 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 SampleSEM Picture of The Sample

Layout of the Sample UsedLayout 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 Resistance variation with TemperatureTemperature

Voltage (V) Temp Deg C R1 R2 R3

none 23.5 75.7 63.12 39.965 24 78.85 64.46 47.94

7.5 27.7 86.67 73.28 51.3510 30.5 91.83 78.13 59.31

12.5 38.5 98.49 85.67 73.6315 42.5 107.68 93.27 81.02

17.5 51.6 114.51 99.1 90.2420 58 121.6 103.58 98.15

Resistance V/S Temperature

0

20

40

60

80

100

120

140

Temperature

Resi

stan

ce75.7 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

23.5 24 27.7 30.5 38.5 42.5 51.6 58

R 1R 2

R 3

A Typical One over f NoiseA Typical One over f Noise

1/f Noise Spectrum from 3 to 300 Hz.

Concluding RemarksConcluding 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 ByContributed By

Kuldeep S. RawatKuldeep S. RawatGraduate StudentGraduate Student

Center for Advanced Computer StudiesCenter for Advanced Computer Studies

Edie LauEdie LauUndergraduate StudentUndergraduate StudentIndustrial TechnologyIndustrial Technology

University of Louisiana, LafayetteUniversity of Louisiana, Lafayette

This study is sponsored by the State of Louisiana Board of Regent This study is sponsored by the State of Louisiana Board of Regent Contract No. LEQSF(1999-02)-RD-A-54Contract No. LEQSF(1999-02)-RD-A-54