Thermal Gradient Management in Stacked Semiconductor Devices
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Solution Overview
Problem
Semiconductor devices experience operating errors due to induced thermal gradients, particularly when closely packed, leading to inappropriate refresh frequencies and data loss in dynamic random access memory (DRAM) due to mismatched thermal sensing and non-uniform power distribution between logic and memory chips.
Innovation Solution
Standardizing the location of thermal sensors across all devices in a stack, allowing the System on a Chip (SoC) to calculate temperature differences and communicate these to DRAM for adjusting refresh rates using a temperature compensated self-refresh circuit, or calculating the maximum temperature gradient to ensure data integrity, even if sensors are not standardized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If semiconductor devices are placed in close physical proximity to reduce transmission length, then system performance is improved, but induced thermal gradients between devices increase
Solution Approach 1:
The patent divides the thermal management function into separate components: individual thermal sensors on each die and a central controller that coordinates refresh operations across multiple dies. This segmentation allows each die to be monitored independently while maintaining system-wide thermal management, resolving the contradiction by enabling close physical proximity without suffering from unmanaged thermal gradients.
Solution Approach 2:
The patent implements a feedback mechanism where thermal sensors continuously monitor temperature on each die and provide data to a controller. The controller uses this feedback information to dynamically adjust refresh frequencies for different dies, thereby compensating for thermal gradients that arise from close physical proximity and non-uniform power distribution.
2Length of stationary object
If multiple memory dies are stacked on a processor die, then transmission length is reduced, but thermal sensing accuracy deteriorates due to non-uniform power distribution
Solution Approach 1:
The patent places individual thermal sensors on each memory die and the processor die rather than using a single thermal sensing system. This segmentation allows each die to have its own thermal monitoring capability, compensating for the non-uniform power distribution that would otherwise degrade thermal sensing accuracy in stacked configurations.
Solution Approach 2:
The patent applies local thermal management by allowing each die to have its own thermal sensor and enabling the controller to apply die-specific refresh frequencies. This local quality approach ensures that thermal sensing accuracy is maintained for each individual die despite non-uniform power distribution across the stacked structure.
3Adaptability or versatility
If thermal sensors are placed in different locations on different dies, then thermal monitoring flexibility is improved, but data comparison accuracy deteriorates due to induced thermal gradients
Solution Approach 1:
The patent uses a feedback-based approach where the controller receives temperature data from thermally coupled sensors on different dies and uses this information to determine appropriate refresh frequencies. The feedback mechanism compensates for location-induced thermal gradients by dynamically adjusting operations based on actual measured temperatures rather than relying on uniform thermal conditions.
Solution Approach 2:
The patent introduces a controller as an intermediary that processes thermal data from multiple sensors and coordinates refresh operations across dies. This intermediary reconciles the temperature differences caused by sensor location variations and thermal gradients, enabling accurate temperature-based decision-making despite the challenges of comparing temperatures from different physical locations.
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 ensures accurate thermal gradient monitoring and adjustment, preventing data loss by optimizing refresh rates and power consumption based on actual thermal conditions, thereby enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
a thermal sensor on the logic die may not be located near the hottest spot of the logic die
Implementation Method 2
induced thermal gradients between one and another of the semiconductor devices
Implementation Method 3
temperature compensated self-refresh circuit
Data Source
AI summary
A temperature difference between a first thermal sensor and a second thermal sensor on a first die is determined. The temperature difference is transmitted from the first die to a circuit on a second die. A temperature from a thermal sensor on the second die is determined. The temperature difference and the temperature from the thermal sensor are utilized on the second die to modify operational characteristics of one or more circuits on the second die.