Pulsed Testing of Through-Body-Vias for Defect Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing techniques for testing through-silicon-vias are inadequate for detecting open circuit conditions due to difficulties in direct probing, which can damage fragile contact pads and lack sophisticated receivers and analog references, making it challenging to reliably assess defects like open circuits.
Innovation Solution
A pulse integration process is used on-board the die, driving pulses of current into through-body-vias and counting until a threshold voltage is reached, allowing for capacitance testing to determine defects such as open conditions without direct probing, utilizing on-board testing circuitry that includes I/O buffers and counters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct probing is used to test through-silicon-vias, then electrical connection can be established, but fragile contact pads are damaged
Solution Approach 1:
The patent introduces an intermediary testing method using pulse integration through existing I/O buffers and back-side contacts, avoiding direct mechanical probing of fragile through-silicon-via contact pads. The pulse integration technique uses electrical signals to indirectly assess via integrity through capacitance measurements, serving as a mediator between the test equipment and the vulnerable via structures.
Solution Approach 2:
The patent replaces the mechanical probing system with an electrical pulse integration system. Instead of using physical probes to directly contact and test through-silicon-vias, the method uses electrical pulses applied through I/O buffers to measure capacitance changes, thereby substituting mechanical contact with electrical field-based measurement that does not physically stress the contact pads.
2Measurement precision
If sophisticated receivers and analog references are used for testing, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent employs the die's own I/O buffers and existing circuit structures to perform the testing function. The I/O buffers serve dual purposes: normal I/O operations and testing through pulse integration. This self-service approach eliminates the need for separate sophisticated receivers and analog references, achieving measurement precision through clever utilization of existing circuit elements rather than adding complex dedicated testing equipment.
Solution Approach 2:
The patent makes the I/O buffers multi-functional by using them for both normal input/output operations and for testing through-body-vias. The same buffer circuits that handle data I/O are also used to generate test pulses and measure capacitance, thereby eliminating the need for separate dedicated testing circuitry and achieving universal functionality with existing components.
3Reliability
If traditional wafer sort testing is used, then testing coverage is achieved, but power consumption increases and process variation sensitivity is high
Solution Approach 1:
The patent uses periodic pulse integration rather than continuous testing signals. By applying a series of discrete pulses and integrating the response, the method achieves reliable defect detection with lower average power consumption compared to continuous traditional wafer sort testing. The periodic nature allows the circuit to remain in low-power states between pulses while still gathering sufficient data for reliable via integrity assessment.
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
This method effectively detects defects in through-body-vias by correlating pulse count with capacitance, providing a reliable estimation of through-body-via integrity without damaging the fragile contact pads, and is suitable for high-volume manufacturing with reduced power consumption and sensitivity to process variations.
Implementation Method 1
A pulse integration process is used on-board the die, driving pulses of current into through-body-vias and counting until a threshold voltage is reached, allowing for capacitance testing to determine defects such as open conditions
Data Source
AI summary
An integrated circuit die has one or more through-body-vias and a testing circuit on board the die which tests for defects in a through-body-via by driving of pulses of current into a node. Pulses are counted until the voltage of the node reaches a threshold voltage to provide a pulse count which is a function of the capacitance of the node. A determination is made as to whether the through-body-via of the node has a defect as a function of the pulse count.