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TLP What is it? Why is it used?. April 2012. Overview. What is TLP? What data does TLP provide you with? What information can TLP pulse variants provide? Additional Measurements during TLP How TLP works? TLP Measurements Q&A. Section 1: What is TLP?.
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TLP What is it?Why is it used? April 2012
Overview • What is TLP? • What data does TLP provide you with? • What information can TLP pulse variants provide? • Additional Measurements during TLP • How TLP works? • TLP Measurements • Q&A
Section 1: What is TLP? • TLP (Transmission Line Pulsing) is a device characterization tool, used to gather detailed information about your protection structure designs • TLP uses a square wave pulse, in a controlled environment and measures the Voltage and Current values gathered during the pulsing • As it is a controlled environment, generally 50 ohms, the gathered data is repeatable, providing reliable information about your protection structure designs • Consecutive, increasing amplitude pulses are used to develop a string of Voltage and Current measurements, which are then used to provide data about your protection structures
Section 2: What data does TLP provide you with? • ESD testing provides limited data about your device, essentially it simply tells you where the protection structure fails, i.e. 1kV failure threshold • TLP provides detailed information about the protection structure • Parameters that can be captured include: • Turn on time (point in voltage when structure reacts) • Snapback voltage • RON resistance • Failure point • Why is this information important? • Characterization of protection structures is important • As it can help designers understand their protection structure designs • It can help predict behavior of the structure during actual ESD events • It can be used to qualify or predict new designs • It can be used to qualify designs on wafer or non-packaged devices
4 3 2 1 Section 2: What data does TLP provide you with? • Device: Snapback Protection Structure 1. Low Voltage TLP Pulses • Open Circuit till turn-on time 2. Snapback Threshold • Begins conducting current • On Resistance • Failure Level • Peak Current
Section 2: What data does TLP provide you with? • Standard TLP (100ns pulse width) • Emulates the energy seen in a Human Body Model (HBM) ESD event • With the use of sequential 100ns TLP pulses, HBM characterization is possible. Device structures can be analyzed but can also be taken to failure. • Using TLP failure levels versus actual ESD test failure thresholds, correlation levels can be determined • Time Domain Reflection (TDR) is the main measurement technique used • VF-TLP (1-10ns pulse widths) • Emulates the event speed and the energy seen in a Charge Device Model (CDM) ESD event • Although the event is similar there are still questions on whether it truly replicates the event • Although VF-TLP testing may not replicate CDM events, it still provides useful data about the reaction protection structures using this fast event
Section 3: What information can TLP pulse variants provide? • Pulse durations • Longer or shorter pulse durations can be used and are accomplished by varying the length of the TLP cable • These will show how different energy levels effect the protection structure designs • Pulse Risetimes • The risetime of standard TLP is ~200ps • Risetimes can be adjusted using risetime filters • Using different risetimes can determine whether the protection structure is effected by the different ramp rates
Section 3: What information can TLP pulse variants provide? • Different Impedances and measurement techniques • Standard TLP impedance is 50 ohms • Uses a Time Domain Reflection (TDR) measurement technique • TDR-O (Overlapping) • TDR-S (Seperated) • Impedance can be changed to different resistance levels. • 25 ohms uses a Time Domain Transmission (TDT) measurement technique • 100 ohms uses a Time Domain Reflection and Transmission (TDR-T) measurement technique • DUT in series with pulse transmission path • 500Ω, 1kΩ Impedance uses High-Z Time Domain Reflection and Transmission (TDR-T) • DUT in series with pulse transmission path
Section 3: What information can TLP pulse variants provide? • Changing the Impedances and Measurement Techniques can provide additional information about the device protection structure • Low Impedance • More current flow for a given voltage • More voltage amplitude • High Impedance • Less current flow for a given voltage • Less voltage amplitude
Section 4: Additional Measurements during TLP In addition to the Voltage and Current data gathered from the TLP measurements, leakage or curve tracing measurements can also be captured • How is TLPdifferent than Curve Tracing? • TLP is a short pulse • Curve Tracing is DC • Shorter pulse • Reduced duty cycle, less heating • Controlled Impedance • Allows device behavior to be observed (more on this later)
Devices for TLP Testing • What kinds of packages can be tested? • Package Level • Wafer Level
Pulse Width TLP Waveforms • What variations are there for TLP waveforms? • Pulse Width • 100ns • 30ns – 500ns • VF-TLP: 1ns – 10ns • Rise Time • 0.2ns – 10ns Rise Time Rise Time
Pulse Width Rise Time TLP Waveforms • How do these variations affect the TLP test? • Pulse Width • Energy under the curve • Rise Time • Device reaction
Section 5: 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
Section 5: How TLP Works • How is a TLP waveform generated? • DUT lies at end of another transmission line • Switch closes • Charge exits Charge Line, propagates towards DUT
Section 5: How TLP Works • How is a TLP waveform generated? • Square waveform • Charge Line behaves as a storage device
Section 5: How TLP Works • 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
Section 5: How TLP Works • How is resistance measured with a TLP pulse? • Square pulse, perceive it as a short-duration Curve Trace TLP DC Curve Trace • Voltage and Current probes measure the DUT
Section 5: How TLP Works • How is resistance measured with a TLP pulse? • Plateau of waveforms are averaged • Device allowed to settle into “quasi-static” state
Section 5: How TLP Works • 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
Section 5: How TLP Works • Sequential TLP pulses produces an I/V Curve
Section 5: How TLP Works • How is the Pulse Width changed? • Length of cable • How is the Rise Time changed? • Low-pass filter added LP
Section 6 TLP Measurement • How devices are measured
Section 6: TLP Measurement • Measurement Goals • Capture Voltage at the DUT • Capture Current through the DUT
Section 6: TLP Measurement • Equipment to deliver TLP pulse to DUT • Wafer Level • DUT (on wafer) • TLP Pulse delivery cable • TLP Pulse delivery probe • Ground Probe • Ground Braid 3 2 5 1 • Package Level • DUT in socket • TLP Pulse delivery cable • Grounded pin 3 4
Section 6: TLP Measurement • Ideally, V and I probes are directly on DUT • Direct placement not possible V/I Probes
Section 6: TLP Measurement • Although probes are not at DUT, measurements are possible V/I Probes • Controlled impedance • Waveform observable any place along path • Time Domain Reflection (TDR)
V/I Probes Section 6: TLP Measurement • 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)
Section 6: TLP Measurement • TDR-S performs waveform addition with software V/I Probes • Waveform addition can also be done in the TLP circuit V/I Probes
V/I Probes Section 6: TLP Measurement • Overlapping waveforms • Incident and Reflected overlap, add together • Overlapped waveform plateau reproduces DUT waveform
Thermo Scientific Questions?
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