Leakage Current Detection in Stacked ICs via Zero-Volt Pin Biasing
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Solution Overview
Problem
Existing test methods for packaged or stacked integrated circuits fail to detect leakage currents on certain paths, particularly when multiple dies are stacked, as they cannot measure currents when the device is not activated or when diodes are in reverse-bias states.
Innovation Solution
A circuit test method that measures leakage currents on signal pins by coupling power pins to ground or applying zero volts, applying a low test voltage to signal pins to ensure all elements are not activated, and measuring currents on other signal pins to detect any leakage beyond a predetermined value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional test methods are used on packaged or stacked integrated circuits, then the testing process is simple, but leakage currents on certain paths cannot be detected
Solution Approach 1:
The test method performs preliminary actions by coupling power pins to ground or applying zero volts before applying test voltages to signal pins. This preliminary configuration ensures that all elements remain inactive during measurement, creating the optimal condition for detecting leakage currents that would otherwise be masked by active device operations.
Solution Approach 2:
The invention changes the voltage parameters applied to different pins systematically. Power pins are set to ground or zero volts while signal pins receive test voltages. This parameter differentiation allows the measurement system to detect small leakage currents on signal paths without interference from active device functionality.
2Area of stationary object
If multiple dies are stacked during packaging to decrease area, then the product area is reduced, but leakage currents on paths induced during stacking cannot be detected by conventional test modes
Solution Approach 1:
Before performing any functional testing that would activate device elements, the method preliminarily configures the device by coupling power pins to ground. This preliminary state ensures that subsequent measurements on signal pins can detect leakage currents from stacking-induced path issues without the masking effect of active device operations.
Solution Approach 2:
The test method extracts the leakage current measurement function from the overall device operation. By isolating the measurement process and performing it in a specially configured state where power pins are grounded, the method can detect path integrity issues specifically without requiring the device to be in its normal operational state.
3Measurement precision
If test voltages are applied to signal pins while power pins are floating or at normal operating voltage, then the device may be activated, but leakage currents cannot be accurately measured
Solution Approach 1:
The method applies preliminary anti-action by coupling power pins to ground or applying zero volts before applying test voltages to signal pins. This counteracts the tendency of the device to activate when voltages are applied, ensuring that elements remain inactive during the measurement process and leakage currents can be detected accurately.
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
Effectively identifies leakage currents on signal pins even when the integrated circuit is not activated, ensuring thorough testing of packaged or stacked devices by preventing false negatives due to diode bias states.
Implementation Method 1
measuring a current on a second signal pin among the plurality of signal pins of the device under test
Data Source
AI summary
A circuit test method for a test device to test a device under test is provided. The circuit test method includes the steps of applying zero volts to a plurality of power pins of the device under test; applying a test voltage to a first signal pin among a plurality of signal pins of the device under test; and measuring a current on a second signal pin among the plurality of signal pins of the device under test and determining whether there is a leakage current in the device under test.