Dynamic Thermal Testing for Stacked IC Dies
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Solution Overview
Problem
Testing stacked integrated circuit dies at specified temperatures is challenging due to heat dissipation and temperature variations among dies in a package, leading to inefficient and lengthy testing processes.
Innovation Solution
Implementing a method that uses thermal and stress sensors to measure the actual temperatures and stresses of each die, allowing for dynamic test conditions to be determined through lookup tables or equations, enabling testing at any temperature range without adjusting each die to fixed specified temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each die is adjusted to fixed specified temperatures using embedded sensors and soaking time, then test accuracy aligns with specification, but testing time increases to tens of minutes
Solution Approach 1:
The patent changes the temperature parameter from fixed specified values to dynamic actual measured values. Instead of adjusting each die to fixed temperatures (−40°C, 25°C, 105°C), the system measures actual temperatures and uses these dynamic values for testing, eliminating the need for prolonged soaking time while maintaining test accuracy through real-time temperature compensation
Solution Approach 2:
The patent extracts the temperature adjustment step from the testing process. By measuring actual temperatures and using them directly for testing, the method removes the time-consuming soaking period required to reach fixed specified temperatures, while still ensuring accurate temperature-dependent testing through real-time temperature data
2Manufacturing precision
If prober chuck temperature is set to specified values, then bottom die testing meets specification, but overlying dies are tested at unknown temperatures due to heat dissipation
Solution Approach 1:
The patent implements feedback by measuring actual temperatures of all dies using embedded sensors and using these measured values to guide the testing process. The system continuously monitors temperature conditions and uses this feedback information to adjust test parameters, ensuring each die is tested at its actual temperature with appropriate compensation
Solution Approach 2:
The patent performs preliminary temperature measurement using embedded sensors before conducting the actual electrical testing. This preliminary action provides accurate temperature information for all dies, allowing the system to compensate for temperature variations and select appropriate test conditions before the dies are tested
3Reliability
If multiple dies are tested sequentially with temperature adjustments, then each die meets test specifications, but overall testing efficiency decreases
Solution Approach 1:
The patent merges the temperature measurement and test condition determination steps into a single integrated process. By measuring all die temperatures simultaneously and determining test conditions based on actual measured temperatures rather than fixed specifications, the system eliminates sequential temperature adjustment steps and enables parallel processing, significantly improving testing efficiency while maintaining reliability
Solution Approach 2:
The patent transitions from static fixed temperature specifications to dynamic actual temperature measurements. The testing system adapts to real-time temperature conditions of each die, allowing simultaneous testing of multiple dies at their respective actual temperatures without requiring sequential adjustment to fixed temperature points, thereby improving productivity while ensuring each die meets its temperature-dependent specifications
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 approach allows for accurate testing of stacked dies at varying temperatures, reducing testing time and ensuring compliance with dynamic specifications, thereby improving testing efficiency and accuracy.
Implementation Method 1
a first temperature of the first die when the first prober chuck is at the target temperature; measuring a second temperature of the second die when the second prober chuck is at the target temperature
Implementation Method 2
a prober chuck may be used to heat a package including stacked dies. The bottom die contacts the prober chuck, and hence can be maintained at the temperature set by the prober chuck
Data Source
AI summary
A plurality of sets of test conditions of a die in a stacked system is established, wherein the plurality of test conditions are functions of temperatures of the die, and wherein the stacked system comprises a plurality of stacked dies. A temperature of the die is measured. A respective set of test conditions of the die is found from the plurality of sets of test conditions, wherein the set of test conditions corresponds to the temperature. The die is at the temperature using the set of test conditions to generate test results.