1. “Impact of Low-Voltage Devices on Test and Inspection”
Teradyne Assembly Test Division Website:
Michael J Smith

2. What’s Driving the Use of Low Voltage Devices?
Cramming more components onto integrated circuits
-“With unit cost falling as the number of components per circuit rises, by 1975 economics may dictate squeezing as many as 65,000 components on a single silicon chip.”
Gordon E. Moore April 19th 1965

3. What’s Driving the Use of Low Voltage Devices?
Increasing functionality
Speed
Memory
Colour
Extended operation
Small size
Disk drives
Larger size
42-inch displays

6. What’s Driving the Use of Low Voltage Devices?
Environmental concerns
Reduce power consumption
Pd = F x C x V²
Restrict heat generation.
Reduce air-conditioning
Less temperature differentiation

7. What’s Driving the Use of Low Voltage Devices?
New functions
Wireless communication.
3G, WiFi, Bluetooth
Combining functions
Cell phone
PDA,
Cameras
GPS
Video

8. What’s Driving the Use of Low Voltage Devices?
The future?
MP3 Jukebox
Portable Mpeg4 video players
Nanotechnology
Remote vehicles

9. What’s Driving the Use of Low Voltage Devices?
The future?
Personal server
Tele-health
Security

10. Azalia Audio Architecture Hyper-Threading Technology
The Next Generation Technology Challenge: Intel’s 2004 Desktop Platform Vision
GMCH
1 PATA port
Next Generation
Int. Gfx core
PCI Express* x16
Discrete Graphics
Azalia Audio Architecture
800MHz FSB
4 Serial ATA ports
RAID0/1
AHCI1
Hyper-Threading Technology
8 Hi-Speed USB 2.0 Ports
4 PCI Express* x1 lanes
PCI Ports
Platform Software
Dual Channel
DDR2-533
MCH
ICH
Higher integration - Smaller gate geometries - Lower voltages

11. The Next Generation Technology Challenge: Intel’s 2004 Desktop Platform Vision
DDR SDRAM @ 2.5 V
Front Side Bus @ 1.2 V
Rambus 64Bit @ 1.8 V
HUB Interface @ 1.5 V
AGP @ 1.5 V
Source : Intel Corp.

12. Voltage Level Technology Trends
10/ V JEDEC 8-5
02/ V JEDEC 8-7
10/ V JEDEC 8-11
05/ V JEDEC 8-12
12/ V JEDEC 8-14
Joint Electron Device Engineering Council
Source : Texas Instrument Technology Roadmap

13. The 1980-90’s Logic Family 5.0V Output Voltage (V) 3.3V High 2.4V 0.8V
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
5.0V
3.3V
Output Voltage (V)
High
2.4V
0.8V
Low
Logic Level

14. 2.5 Volt Logic - JEDEC 8-5 5.0V Output Voltage (V) 3.3V High 1.7V 0.7V
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
5.0V
3.3V
Output Voltage (V)
High
1.7V
0.7V
Low
Logic Level
Joint Electron Device Engineering Council

15. 1.8 Volt Logic - JEDEC 8-7 5.0V Output Voltage (V) 3.3V High 0.65V
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
5.0V
3.3V
Output Voltage (V)
High
0.65V
0.35V
Low
Logic Level
Joint Electron Device Engineering Council

16. 1.5 Volt Logic - JEDEC 8-11 5.0V Output Voltage (V) 3.3V High 0.65V
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
5.0V
3.3V
Output Voltage (V)
High
0.65V
0.35V
Low
Logic Level
Joint Electron Device Engineering Council

17. 1.0 Volt Logic - JEDEC 8-14 5.0V Output Voltage (V) 3.3V High 0.65V
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
5.0V
3.3V
Output Voltage (V)
High
0.65V
0.35V
Low
Logic Level
Joint Electron Device Engineering Council

18. 1.0 Volt Logic - JEDEC 8-14 5.0V Maximum High = 200mV above VDD
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
5.0V
Maximum High = 200mV above VDD
Maximum Low = -200mV below GND
3.3V
Output Voltage (V)
Maximum High
0.65V
0.35V
Minimum Low
Logic Level
Joint Electron Device Engineering Council

19. What Are the Issues? V - Voltage: I - Current: 1.0 Volt Logic
200mV below GND and 200mV above VDD JEDEC
1.5 & 1.8 Volt Logic
300mV below GND and 300mV above VDD JEDEC
Intel AGTL signal
350mV for Intel AGTL signal for only 10nS
500mV for 15pS
I - Current:
90nm technology
No more than 100mA through each output
Joint Electron Device Engineering Council

20. Outside the Safe Operating Area?
Over-Voltage and Over-Current Failure
These failures taken place in milliseconds - once the second breakdown region has been reached, the transistor will enter a negative resistance state, and there is nothing that will prevent total failure.
A close-up view (right) with greater damage. A large section of the die has exploded from the failure point outwards, and molten silicon has been sprayed all over the die. This failure would almost certainly indicate a short on all terminals (provided bonding wires are intact).
ON Semiconductor

21. Newer Parts Are More Sensitive to Over-Voltage Conditions
As core and I/O Voltages decrease, so must the transistor gate oxide thickness
Thinner oxides break down at lower voltages
Graph is for a 100ppm failure rate

22. 90nm Generation Gate Oxide
Leakage through the silicon dioxide layer of a gate increases exponentially as its thickness decreases. Nevertheless, making the dielectric ever thinner is necessary in order to meet increasing performance goals.
When the gate dielectric of a transistor thins, its insular quality decreases and current leaks through it.
Uncontrolled, this conduction causes the transistor to stray from its purely "on" and "off" state and into an "on" and "leaky off" behavior. The effect is similar to that of a light bulb that lights fully when turned on but only dims when you turn the light switch off.
1.2nm
Thick
Gate Oxide is less than 5 atomic layers

23. Newer Parts Are More Sensitive to Over-Voltage Conditions (SOA)
Today’s processors have strict over-voltage/time specification
AGTL signals should not exceed 1.8V, always for < 10nsec
Source : Intel Corp. Itanium 2 processor datasheet

24. Over-Current-Related Failures
(Joule heating)
Bondwire fusing or bambooing
Die metallization failure

25. Over-Voltage-Related Failures
CMOS latch-up
A self sustaining short from VDD to GND

26. Over-Voltage-Related Failures
Gate oxide breakdown, time dependent dielectric breakdown (TDDB)
Time Dependent Breakdown of Ultrathin Gate Oxide
By Abdullah M. Yassine, Member, IEEE, H. E. Nariman, Member, IEEE, Michael McBride, Mirac Uzer, Member, IEEE,and Kola R. Olasupo, Member, IEEE

27. Over-Voltage-Related Failures
Electrostatic Discharge (ESD) damage
Damaged Protection diode
This transistor was also confirmed failed by ESD. You can see where the discharge energy surge has buried through the weakest point(s) in the oxide layer through to the silicon. Bipolar devices are becoming very small and susceptible to ESD.
Photos Rohm Electronics

28. What does this mean for Electrical Test
In-circuit
Tight control of voltage and current
Minimize Noise
Fixture, Feedback etc
Functional Test
Boundary Scan and BIST
Ground Bounce

29. The Difficulty of Programming the Correct Voltage Levels
Simple Voltage Divider
Maximum Output drive current of 100mA at 0.6 Voltages
R = V/I ~ 6 Ohms
Older Driver Output Impedance
~ 5 Ohms
Connection Resistance
Wire
Relays
Contact
~ 1 Ohm
5 Ohms Output Impedance +
1 Ohm wiring, relay and contact resistance
0.6V
Equivalent Output Resistance
6 Ohms
1.2V
Driver
0.6V

30. The Difficulty of Programming the Correct Voltage Levels
710mV
Under
Load
Actual example of a non custom design driver sensor

31. The Difficulty of Programming the Correct Voltage Levels
DUT
1.2V Logic
Backdriven Part
1.2V Logic
High
Low
20mA
0.98V
0.62V
5 Ohm
1 Ohm
Vprog = 1.2V
(+/- 100mV)
20mV
Driver
100mV
80mA
5 Ohm
1 Ohm
Vprog = 1.2V
(+/- 100mV)
80mV
Driver
400mV

32. The Difficulty of Programming the Correct Voltage Levels
DUT
1.2V Logic
Backdriven Part
1.2V Logic
High
Low
20mA
1.68V
1.12V
5 Ohm
1 Ohm
Vprog = 1.7V
(+/- 100mV)
20mV
Driver
100mV
80mA
5 Ohm
1 Ohm
Vprog = 1.7V
(+/- 100mV)
80mV
Driver
400mV

33. The Difficulty of Programming the Correct Voltage Levels
For 4 logic families you may need 8 sensor levels to measure both inputs and outputs voltages
1.0V
1.2V
1.4V
1.2V
High impedance in-circuit drivers, require different programmed outputs to match the device output currents.
1.7V
1.5V
1.5V
1.9V
1.8V
1.8V
Backdriven currents could range from 80mA’s to 500mA’s
2.2V

34. The Difficulty of Programming the Correct Voltage Levels
DUT
DUT
1.2V Logic
Backdriven Part
1.2V Logic
High
Low
20mA
0.98V
5 Ohm
1 Ohm
Vprog = 1.2V
(+/- 100mV)
20mV
Driver
100mV
20mA
5 Ohm
1 Ohm
Vprog = 1.2V
(+/- 100mV)
20mV
Driver
100mV

35. The Difficulty of Programming the Correct Voltage Levels
DUT
DUT
1.2V Logic
Backdriven Part
1.2V Logic
High
Low
20mA
0.62V
5 Ohm
1 Ohm
Vprog = 1.2V
(+/- 100mV)
20mV
Driver
100mV
80mA
5 Ohm
1 Ohm
Vprog = 1.2V
(+/- 100mV)
80mV
Driver
400mV

36. Spikes Are Caused By Changing States
V = L x I t
DUT
Backdriven Part
Isolation,
Force a Logic high
Stimulus
Measurement
Uncontrolled Voltage Spikes result from outputs changing while they are being backdriven
Example:When back driving a low to a high and the back driven output changes, the out signal now re-enforces the back drive level and the current has to go from a positive current to zero.

37. Spikes Are Caused By Changing States
Example:
Greater than 9V Voltage Spike Measured!
Can cause CMOS latch-up failures or TDDB

38. Tri-stated or Back-driven?
With complex devices can we really be sure that our big devices are tri-state?
Tri-state back-drive <10mA
Output back-drive >80mA
Limits of 100mA?

39. Tri-stated or Back-driven?
An analysis of a typical in-circuit test program of a PC motherboard found that back-driving occurred during 30% of the digital device tests.
A total of 156 back-driving events requiring greater than 50mA of back-driving current were recorded.
Median back-drive current
176mA.
Highest back-drive current
600mA.
Longest back-drive duration
2.5mS.

40. Functional Test Functional Test Boundary Scan and BIST
Tight control of voltage and current
Low impedance and feedback
Minimize Noise
Fixture design
Boundary Scan and BIST
External circuits will need to match logic families
Fixture and interface design
Ground Bounce

41. Potential Impact Damaged or Stressed Components Reduced Fault Coverage
Catastrophic or latent failures related to
Gate Oxide Breakdown
ESD Diode overstress
CMOS Latch-up
Reduced Fault Coverage
Unable to test components without violating device specifications
Increased False Failures
Needless replacement of good devices
Cost of repair and associated retest
Possible damage to product during repair
Longevity of reworked product vs. product that is untouched

42. What Is Needed to Prevent Damage?
Driver Voltage and Current Verification
Low impedance, closed loop measurement
Per Pin Programmable Voltage Levels
>5 logic families per device ( 1.0,1.2,1.5,1.8,2.5 and 3.3)
Hardware Back-drive Limits for both Current and Time
100mA’s maximum or ANY limit that is considered safe
High Speed Digital Controller
Minimize test time
Multi level Software Isolation
Eliminate noise, clocks and feedback loops.

43. Technical Papers
Reliability limits for the gate insulator in CMOS technology
By J. H. Stathis
CMOS scaling beyond the 100-nm node with silicondioxide-based gate dielectrics
By E. Y. Wu,E. J. Nowak,A. Vayshenker,W. L. Lai,D. L. Harmon
Degradation and Breakdown of Thin Silicon Dioxide Films Under Dynamic Electrical Stress
Montserrat Nafr´ıa, Jordi Su˜n´e, David Y´elamos, and Xavier Aymerich
Time Dependent Breakdown of Ultrathin Gate Oxide
By Abdullah M. Yassine, Member, IEEE, H. E. Nariman, Member, IEEE, Michael McBride, Mirac Uzer, Member, IEEE,and Kola R. Olasupo, Member, IEEE
Issues and Challenges of Testing Modern Low Voltage Technologies with Traditional In-circuit Testers
Alan Albee, APEX 2004

44. “Impact of Low-Voltage Devices on Test and Inspection”
Teradyne Assembly Test Division Website:
Michael J Smith