DUT Waveform Measurement Using Transmission Line Delay Compensation
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Solution Overview
Problem
Direct probing of devices under test (DUT) on semiconductor wafers is challenging due to electrical safety and contamination concerns, and high-frequency measurements are distorted by inappropriate signal branching and transmission line effects.
Innovation Solution
A method involving outputting electrical signals, measuring voltages at specific points in the measurement instrument, and using analog-to-digital converters (ADCs) to determine DUT waveforms by accounting for propagation delays and transmission line characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct probing of DUT on wafer is performed, then measurement access is improved, but electrical safety and wafer contamination risks increase
Solution Approach 1:
The patent uses transmission line modeling and mathematical calculations as an intermediary method to determine DUT waveforms without direct physical contact. By measuring voltages at the measurement instrument and using propagation delay calculations, the system indirectly obtains DUT signal characteristics, eliminating the need for direct probing and thus avoiding electrical safety hazards and contamination risks.
2Measurement precision
If signal branching is used to monitor DUT signal, then measurement capability is improved, but signal distortion increases due to transmission line effects
Solution Approach 1:
The patent employs feedback by measuring the actual voltages at the measurement instrument (V1 and V2) and using these measurements along with known transmission line parameters to calculate the true DUT waveform. This feedback approach allows the system to compensate for transmission line effects and determine the actual DUT signal without direct signal branching that would cause distortion.
Solution Approach 2:
The patent changes the measurement parameters by measuring voltages at the measurement instrument rather than directly at the DUT, and uses propagation delay (time parameter) as a key variable in the calculation. By transforming the measurement location and using time-delayed voltage measurements, the system avoids signal distortion while maintaining measurement capability.
3Measurement precision
If monitor terminal is placed at DUT, then measurement accuracy is improved, but DUT characteristics are affected
Solution Approach 1:
The patent uses the measurement instrument and transmission line modeling as an intermediary system to determine DUT waveforms without placing monitor terminals directly on the DUT. By calculating the DUT waveform from measurements taken at the measurement instrument using propagation delay and voltage measurements, the system maintains measurement accuracy while preserving DUT characteristics and avoiding any loading effects.
Data Source
AI summary
Methods, systems, and computer readable media for measuring voltage and current waveforms at devices under test. An example method includes outputting an electrical signal from a signal generator of a measurement instrument; measuring a first voltage at an input to an output resistance of the measurement instrument; measuring a second voltage at an output of the output resistance of the measurement instrument; and determining a test measurement voltage at a device under test (DUT) electrically connected to the measurement instrument using the first voltage, the second voltage, and a propagation delay of a transmission line electrically connecting the measurement instrument to the DUT.