Introduction to Transmission Line Pulse - Thermo … Background •Characterization of protection...

Introduction to

Transmission Line Pulse

(TLP)

2

Overview

1. What is TLP

2. How TLP works

3. TLP measurement

4. TLP variants

5. Interpreting TLP data

6. TLP Precision

7. VF-TLP

8. Q&A

3

History

• Transmission Line Pulse

• Introduced as a possible method to emulate energy in HBM

• Determined that for a given peak current, a TLP pulse of 100ns

carries the same energy as HBM

• Same energy is produced by different voltages:

50V TLP = 1A

1500V HBM = 1A

-50 0 50 100 150 200 250

4

Background

• Characterization of protection structures is important

• Predict behavior for real world events

• Important parameters:

• Snapback voltage

• Turn on time

• RON resistance

• Failure point

• Must determine parameters with techniques similar to ESD

• TLP is an excellent solution

• Controlled impedance makes measurements easier

• Low duty cycle prevents heating

5

Section 1

What is TLP

6

Section 1: What is TLP

• What makes TLP different than ESD?

• ESD tests simulate real world events

• HBM, MM, IEC, CDM

• ESD tests record failure level

• “Qualification”

• TLP does not simulate any real-world event

• TLP tests record failure level and device behavior

• “Characterization”

TLP Waveform

-20 0 20 40 60 80 100 120

T ime (ns)

Volt

age

7

Section 1: Device Characterization

What is Device Characterization?

• Describes the resistance of a device for a given stimulus

• Resistance = Voltage / Current

• Conventionally performed by increasing amplitude until failure

• Like Curve Tracing -0.1

0.4

0.9

1.4

1.9

2.4

2.9

0 5 10 15

VD U T (V)

I DU

T (

A)

8


How is TLP different than Curve Tracing?

• Curve Tracing is DC • TLP is a short pulse

• Shorter pulse

• Reduced duty cycle, less heating

• Controlled Impedance

• Allows device behavior to be observed (more on this later)

Time

Vo

lta

ge

T ime

Vo

lta

ge

9


• How is TLP the same as Curve Tracing?

• Measure resistance of device with increasing voltage

• Less heat means higher voltage before failure

DC Curve Trace TLP

Time

Vo

lta

ge

T ime

Vo

lta

ge

10


• What can I learn from Device Characterization with TLP?

• Turn-on time

• Snapback voltage

• Performance changes with rise time 0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 2 4 6 8 10 12

VDUT (V)

I DU

T (

A)

11

Section 1: TLP Waveforms

What does a TLP waveform look

like?

TLP Waveform

-20 0 20 40 60 80 100 120

T ime (ns)

Volt

age

• Square pulse

• Unlike ESD waveforms, TLP does not

mimic any real world event

HBM Waveform MM Waveform

12

TLP Waveform

-20 0 20 40 60 80 100 120

Time (ns)V

olt

ag

e

TLP Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Vo

lta

ge


What variations are there for TLP waveforms?

• Pulse Width

• 100ns

• 30ns – 500ns

• VF-TLP: 1ns – 10ns

TLP Waveform

-20 0 20 40 60 80 100 120

T ime (ns)

Volt

age

Pulse Width

• Rise Time

• 0.2ns – 10ns

Rise Time Rise Time

13


How do these variations affect

the TLP test?

• Pulse Width

• Energy under the curve

-20 0 20 40 60 80 100 120

Time (ns)

Vo

lta

ge

Pulse Width

• Rise Time

• Device reaction

-20 0 20

Time (ns)

Vo

lta

ge

Rise Time

14

Section 1: Devices for TLP Testing

• What kinds of packages can be tested?

• Package Level

• Wafer Level

15

Section 2

How TLP Works

• How TLP pulses are generated

16

Section 2: How TLP Works

• How is a TLP waveform generated?

• Transmission Line connected to power supply

• Called Charge Line

• Length proportional

to pulse width

• Power supply charges the cable

17


• How is a TLP waveform generated?

• DUT lies at end of another transmission line

• Switch closes

• Charge exits Charge Line, propagates towards DUT

18


How is a TLP waveform generated?

• Square waveform

• Charge Line behaves as a storage device

-20 0 20 40 60 80 100 120

Time (ns)

Vo

lta

ge

19


• What happens when the waveform hits the DUT?

• Recap: TLP is a short-duration pulse in a controlled-impedance environment

• Behaves like an RF signal

• RF signal behavior

• Propagates until impedance changes

20


• How is resistance measured with a TLP pulse?

• Square pulse, perceive it as a short-duration Curve Trace

• Voltage and Current probes measure the DUT

DC Curve Trace TLP

21


How is resistance measured with a TLP pulse?

Current Probe Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Cu

rre

nt

• Plateau of waveforms are averaged

• Device allowed to settle into “quasi-static” state

Voltage Probe Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Vo

lta

ge

22


• Why use both a Voltage probe and a Current probe?

• It is possible to calculate DUT resistance with only 1 probe

• VDUT = VPulse – (IDUT * ZTLP)

• IDUT = (VPulse – VDUT) / ZTLP

• Not desirable because extremes are noisy

Current Probe Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Cu

rre

nt

Voltage Probe Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Volt

ag

e

23


Sequential TLP pulses produces an I/V Curve

Snapback Device

0

0 . 0 5

0 . 1

0 . 15

0 . 2

0 . 2 5

0 . 3

0 . 3 5

0 . 4

0 . 4 5

0 2 4 6 8 10 12

VDUT (V)

ID

UT (

A)

Resistor

0

0.05

0.1

0.15

0.2

0.25

0.3

0 5 10 15 20 25 30

VDUT (V)

ID

UT (

A)

OPEN Circuit

- 0 . 1

0 . 4

0 . 9

1. 4

1. 9

0 5 10 15 2 0 2 5 3 0

VDUT (V)

ID

UT (

A)

SHORT Circuit

0

0 . 1

0 . 2

0 . 3

0 . 4

0 . 5

0 . 6

0 0 . 2 0 . 4 0 . 6 0 . 8 1

VDUT (V)

ID

UT (

A)

24


• How is the Pulse Width changed?

• Length of cable

How is the Rise Time changed?

• Low-pass filter added

LP

25

Section 3

TLP Measurement

• How devices are measured

26

Section 3: TLP Measurement

• Measurement Goals

• Capture Voltage at the DUT

• Capture Current through the DUT

27


• Equipment to capture V and I

Current Probe

Oscilloscope

Voltage Probe

28


• Equipment to deliver TLP pulse to DUT

Package Level 1. DUT in socket

2. TLP Pulse delivery cable

3. Grounded pin

Wafer Level 1. DUT (on wafer)

2. TLP Pulse delivery cable

3. TLP Pulse delivery probe

4. Ground Probe

5. Ground Braid

1

2

3 4

5

3

29


• Ideally, V and I probes are directly on DUT

• Direct placement not possible

V/I Probes

30


• Although probes are not at DUT, measurements are possible

• Controlled impedance

• Waveform observable any place along path

• Time Domain Reflection (TDR)

V/I Probes

31


• How are measurements accomplished away from DUT?

• Incident and Reflected waveforms

• Adding the waveforms reproduces DUT measurement

• Incident and Reflected waveforms are recorded separately (TDR-S)

V/I Probes

32


Reflected

Waveform

Polarity

DUT Ω > ZTLP (Example: Open Circuit)

DUT Ω < ZTLP (Example: Short Circuit)

DUT Ω = ZTLP (Example: 50 Ω Resistor)

Voltage

Waveform

Current

Waveform

Positive Reflection

Positive Reflection

Negative Reflection

Negative Reflection

No Reflection

No Reflection

33


• TDR-S performs waveform addition with software

V/I Probes

V/I Probes

Waveform addition can also be done in the TLP circuit

34


• Overlapping waveforms

• Incident and Reflected overlap, add together

• Overlapped waveform plateau reproduces DUT waveform

V/I Probes

35

Section 4

TLP Variants

36

Section 4: Importance of Impedance

• Low Impedance

• More current flow for a given voltage

• More voltage amplitude

• High Impedance

• Less current flow for a given voltage

• Less voltage amplitude

Why vary the impedance?

37

Section 4: TLP Variants

• TLP circuit characteristics up to this point

• 50 Ω Impedance

• One stress-pin

• One ground-pin

• Variations alter the system impedance and grounding style

Pulser

D

U

T

Incident

Reflected

Absorbed V and I to

Scope

• Time Domain Reflection (TDR)

• TDR-O

• TDR-S

38


• Time Domain Transmission (TDT)

• 25Ω system impedance

Pulser

D

U

T

Scope Ch3

Incident

Reflected

Absorbed

Transmitted

V and I to

Scope

39


• Time Domain Reflection and Transmission (TDR-T)

• DUT in series with pulse transmission path

• 100Ω Impedance

Pulser

DUT

Scope Ch3

Incident

Reflected Absorption Transmitted

V and I to

Scope

40


• High-Z Time Domain Reflection and Transmission (TDR-T)

• DUT in series with pulse transmission path

• 500Ω, 1kΩ Impedance

Pulser

DUT

Scope Ch3

Incident

Reflected Absorption Transmitted

V and I to

Scope

High-Z Ω

41

Section 5

Interpreting TLP Data

42

Section 5: Interpreting TLP I/V Curves

• What information do TLP I/V

Curves provide?

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 2 4 6 8 10 12

VD U T (V)

I DU

T (

A)

Voltage Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Vo

lta

ge

Current Waveform

-20 0 20 40 60 80 100 120

Time (ns)

Cu

rre

nt

• What information do TLP

waveforms provide

43


• Device: Resistor

• Ω is constant no matter what

voltage is applied

Resistor

0

0.05

0.1

0.15

0.2

0.25

0.3

0 5 10 15 20 25 30

VDUT (V)

I DU

T (

A)

44


• Device: Zener Diode

• Turn-on Voltage

• Breakdown Voltage

- 0 . 1

0

0 . 1

0 . 2

0 . 3

0 . 4

0 . 5

0 2 4 6 8 10

VDUT (V)

ID

UT (

A)

- 0 . 1

0

0 . 1

0 . 2

0 . 3

0 . 4

0 . 5

0 2 4 6 8 10

VDUT (V)

ID

UT (

A)

- 0 . 4

- 0 . 3 5

- 0 . 3

- 0 . 2 5

- 0 . 2

- 0 . 15

- 0 . 1

- 0 . 0 5

0

0 . 0 5

- 15 - 10 - 5 0

VDUT (V)

ID

UT (

A)

45

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 2 4 6 8 10 12

VDUT (V)

I DU

T (

A)


• Device: Snapback Protection

Structure

1. Low Voltage TLP Pulses

• Open Circuit

2. Snapback Threshold

• Begins conducting current

1

3

3. On Resistance

4. Failure Level

• Peak Current

4

2

46

Section 5: Interpreting TLP Data

• How is failure detected?

• DC leakage test after

each TLP pulse

Begin Test Procedure

Stop

Apply stress pulse

to the DUT

Record Voltage &

Current waveforms

DC

Leakag

e test

Max

pulse

amplitud

e

reached?

Increase stress

pulse amplitude

PASS

FAIL

NO

YES

47



TLP Pulser

SourceMeter, etc.

V & I to Scope

D

U

T

TLP Pulser

SourceMeter, etc.

V & I to Scope

D

U

T

48



-0.2

0

0.2

0.4

0.6

0.8

1

1.2

-2 0 2 4 6 8 10 12 14

VDUT (V)

ID

UT (A

)

0.0001 0.001 0.01 0.1 1

ILeakage (A)

IV Chart

Leakage (A)

• DC Leak Test

• Force 14V

• 10mA Compliance

• >9mA Failure

49

Section 5: Load Lines

• Precise amount of energy under curve

• Controlled impedance circuit

• Conservation of energy

• Pulsed = VDUT + (IDUT * ZTLP)

• For a given TLP Amplitude, the

measured V and I will always reside

on that Amplitude’s Load Line

IDUT

VDUT

Load Line

-20 0 20 40 60 80 100 120

Time (ns)

Vo

lta

ge

50

VDUT

IDUT


Open Circuit:

Short Circuit:

VPulse VDUT IDUT

50 50 0

100 100 0

150 150 0

200 200 0

250 250 0

VPulse VDUT IDUT

50 0 1

100 0 2

150 0 3

200 0 4

250 0 5

VDUT

IDUT

51

VDUT

IDUT


50Ω Circuit:

Snapback Device:

VPulse VDUT IDUT

50 25 0.5

100 50 1

150 75 1.5

200 100 2

250 125 2.5

VPulse VDUT IDUT

50 50 0

100 100 0

150 150 0

200 60 2.8

250 70 3.6

VDUT

IDUT

52

Section 5: Load Lines and System Impedance

• How does system impedance affect the Load Line?

• Low Impedance

• More current flow for a given voltage

• High Impedance

• Less current flow for a given voltage

• VPulse = VDUT + (IDUT * ZTLP)

• IDUT = (VPulse - VDUT) / ZTLP

50Ω

250Ω

|

50

VDUT

IDUT

|

100

|

150

|

200

|

250

1 --

2 --

3 --

4 --

5 --

53

Section 5: System Impedance

• Why would I want to change the system impedance?

• Snapback device recap:

• Voltage triggered

• Fails by peak current

• What if Snapback device

has high trigger voltage,

low peak current?

• 250V Trigger Voltage

• 5A peak current

|

50

VDUT

IDUT

|

100

|

150

|

200

|

250

1 --

2 --

3 --

4 --

5 --

50Ω

250Ω

54

Section 5: System Impedance

• Characteristics of High Impedance

• Longer settling time

• Time Constant = ZTLP * CDUT

• Unstable turn-on region

• Enough Voltage to turn-on

• Not enough Current to remain on

50 Ω 500 Ω 1000 Ω

55

Section 5: Quasi-Static Region

• What defines the “quasi-static” region?

• After transient response has settled

• What if the device never settles?

-0.01

0.01

0.03

0.05

0.07

0.09

0.11

-1 4 9 14

VDUT (V)

ID

UT (

A)

30%

40%

50%

60%

70%

80%

Transient

Quasi-Static

30

40

50

60

70

80

30

40

50

60

70

80

56

Section 5: Transient Region

• Does the transient response tell me anything?

• Turn-on time

• Capacitance

Zener Waveform (TDR-S)

-20 20 60 100 140 180 220 260 300

Time (ns)

Volt

ag

e

57

Section 6

TLP Accuracy

• Understand limitations

• Optimize measurements

58

Section 6: TLP Accuracy

• Misconception: TLP is as precise as DC curve tracing

• What affects the accuracy of TLP measurements?

• Short duration means smaller sample size

• Measurement instrument limitations

• Parasitics and noise

• Contact resistance

• How are these limitations addressed?

59

Section 6: TLP Accuracy – How Are Limitations Addressed?

Oscilloscope: Bandwidth

Sample Rate

500Mhz Bandwidth

-1.5 0.5 2.5 4.5 6.5

Time (ns)

6Ghz Bandwidth

-1.5 0.5 2.5 4.5 6.5

Time (ns)

60

Oscilloscope: Sampling rate

Sample Rate

500 MHz, 5 GS

-1.5 0.5 2.5 4.5 6.5

T ime (ns)

Volt

age

6 GHz, 20 GS

-1.5 0.5 2.5 4.5 6.5

Time (ns)

Volt

age


61

TDR-O: No Optimization

-100

-75

-50

-25

0

25

50

75

100

125

150

175

200

225

250

-10 40 90

Time (ns)

Volt

ag

e

Oscilloscope: Signal digitization optimization

• 8 bits of resolution = 256 possible levels

TDR-O: Optimized Quasi-Static Region

-10

-5

0

5

10

15

-10 40 90

Time (ns)

Volt

ag

e


62


0

1

2

3

4

5

6

7

8

-1 -0.5 0 0.5 1

VDUT (V)

ID

UT (

A)

No Adaptive Ranging

Adaptive Ranging


63


• Overlapped waveform advantageous for best resolution

TDR-S: No Optimization Possible

-250

-150

-50

50

150

250

-20 30 80 130 180 230

Time (ns)

Vo

lta

ge


64

UNCORRECTED Open Circuit

0

0.1

0.2

0.3

0.4

0.5

0 5 10 15 20 25

VD U T (V)

I DU

T (

A)

CORRECTED Open Circuit

0

0.1

0.2

0.3

0.4

0.5

0 5 10 15 20 25 30

VD U T (V)

I DU

T (

A)

UNCORRECTED Short Circuit

0

0.1

0.2

0.3

0.4

0.5

0 0.5 1 1.5 2

VD U T (V)

I DU

T (

A)

• Parasitics:

• Factor out from DUT measurement

CORRECTED Short Circuit

0

0.1

0.2

0.3

0.4

0.5

0 0.5 1 1.5 2

VD U T (V)

I DU

T (

A)


65

• Noise:

• Multiple pulses

Averaged

Voltage Waveform

-20 0 20 40 60 80 100 120

Time (ns)


66

• Contact Resistance

• Changes on each touchdown

• 4-point TLP (Kelvin)

• Contact resistance removed

+

_

DUT

I V

H V

Scope

V-

V+

Ω Ω


67

Section 7

VF-TLP

• Similarities and differences

• Additional requirements

68

Section 7: VF-TLP

• What makes VF-TLP different?

• Short pulse width

• 1ns – 10ns

• Fast rise time

• 100ps – 200ps

• Mimics CDM event

• Transient response emphasized

69

TLP Waveform

-0.25 0 0.25 0.5 0.75 1 1.25

Time (ns)

V

Section 7: VF-TLP

• Additional requirements for VF-TLP?

• Oscilloscope bandwidth

• 200ps rise time = 5 GHz

• Oscilloscope sampling rate

• 1ns @ 20GS/sec = 20 samples

70

Package Level

Section 7: VF-TLP

• Additional requirements for VF-TLP?

• More sensitive to parasitics

• Wafer-level only

• RF-rated probes recommended

Coax Wafer Probe - 4 GHz RF Wafer Probe - 40 GHz

71

Additional Topics

• How do I power up my device during TLP?

• DC BIAS supplies can be added

TLP Pulser

V & I to Scope

D

S

G

DC Supply

72

Additional Topics

• Does TLP correlate to HBM?

• Does VF-TLP correlate to CDM?

• Why use TLP instead of a TDR machine, or solid state pulse

generator?

• TLP Circuit is a closed system, will reflections continue

indefinitely?

Introduction to Transmission Line Pulse - Thermo … Background •Characterization of protection...

Documents

Transcript of Introduction to Transmission Line Pulse - Thermo … Background •Characterization of protection...