TDDB Test Structure with Current Restraint for Parallel Dielectric Testing
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Solution Overview
Problem
Time-dependent dielectric breakdown (TDDB) tests in integrated circuit manufacturing are time-consuming due to the need for large sample sizes to ensure statistical significance, which increases the test cycle significantly.
Innovation Solution
A TDDB test structure and method involving multiple test units connected in parallel with a current restraint unit, utilizing DEPFET transistors and resistors to restrain breakdown currents, allowing for batch testing and reducing test time by turning off DEPFET transistors after breakdown, thereby preventing further current flow and allowing other samples to be tested under constant voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one-by-one TDDB testing is performed to ensure accurate results, then measurement precision is improved, but loss of time increases significantly
Solution Approach 1:
The testing system is segmented into multiple independent test units (first test unit, second test unit, etc.), each capable of testing a dielectric test sample independently. This allows parallel testing of multiple samples simultaneously, reducing total test time while maintaining individual sample measurement accuracy through dedicated current restraint mechanisms in each unit.
Solution Approach 2:
Multiple test units are combined into a single integrated testing system that applies constant voltage across all units simultaneously. The system merges the testing capability of multiple units while using a unified constant voltage source and ground connection, enabling batch testing of multiple dielectric samples in parallel to significantly reduce test cycle time.
2Reliability
If large sample size is used to ensure statistical significance, then reliability of test results is improved, but loss of time increases due to extended test cycle
Solution Approach 1:
The system segments the testing process into multiple parallel test units, each handling one dielectric test sample independently with its own current restraint unit. This segmentation allows simultaneous testing of multiple samples (increasing effective sample size for statistical significance) while maintaining manageable individual test durations through parallel execution.
Solution Approach 2:
The constant voltage is applied continuously across all test units simultaneously, and the electronic measurement system continuously monitors breakdown currents in real-time across all units. This continuous parallel action enables testing of multiple samples at the same time, providing large statistical sample sizes without extending the test cycle duration.
3Productivity
If parallel testing of multiple dielectric samples is performed, then productivity is improved, but device complexity increases due to additional current restraint units
Solution Approach 1:
The system uses segmented, modular test units where each unit contains its own current restraint unit with DEPFET transistors and resistors. This modular segmentation allows parallel testing (improving productivity) while keeping each unit's complexity manageable and standardized, making the overall system scalable without proportionally increasing operational complexity.
Solution Approach 2:
Each test unit uses identical universal components (DEPFET transistors, resistors, constant voltage connections) that serve multiple functions: current restraint during normal operation, breakdown detection, and automatic switching. This universality allows parallel testing of multiple samples (increasing productivity) while using standardized components that reduce overall system complexity through repetition rather than customization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables batch testing of dielectric samples, significantly reducing test time compared to one-by-one testing while maintaining accurate results, by effectively managing breakdown currents and allowing continuous stress on un-failed samples.
Implementation Method 1
a current restraint unit connected between the dielectric test sample and the ground, for restraining a breakdown current from flowing on the dielectric test sample after the breakdown of dielectric test sample
Implementation Method 2
wherein a cross voltage of the resistor caused by the breakdown current is greater than an absolute of a total threshold voltage of the at least one DEPFET transistor
Implementation Method 3
TDDB (Time Dependent Dielectric Breakdown) test is an important method to evaluate the reliability of dielectric materials
Data Source
AI summary
A time dependent dielectric breakdown test structure includes a plurality of test units connected in parallel between a constant voltage and a ground. Each of the plurality of test units includes a dielectric test sample connected to the constant voltage; and a current restraint unit connected between the dielectric test sample and the ground, for restraining a breakdown current from flowing on the dielectric test sample after the constant voltage has broken the dielectric test sample.