Thermal Event Sensor Passive Charge Loss Detection
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Solution Overview
Problem
There is a need to detect potential tampering or exposure to extreme temperatures in semiconductors and integrated circuits throughout the supply chain, as tampering can cause performance failures with severe consequences.
Innovation Solution
A thermal event sensor utilizing a charge storage component that loses charge at a temperature-dependent rate, coupled with a sensing interface and readout mechanism, allows for passive detection of thermal events by sensing the remaining charge, which can indicate exposure to extreme temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal event sensor uses a charge storage component that loses charge at a temperature-dependent rate, then the sensor can detect thermal events passively without power, but the charge loss rate may be influenced by normal temperature variations during supply chain handling
Solution Approach 1:
The patent applies preliminary action by establishing a baseline charge level at a defined reference point in the supply chain (such as at manufacturing or distribution center). This baseline serves as a reference against which all subsequent charge measurements are compared, allowing the system to distinguish between charge loss from normal handling temperatures versus charge loss from extreme thermal events. The baseline is set before the component enters the monitoring phase, enabling passive detection without requiring continuous power.
Solution Approach 2:
The patent utilizes parameter changes by leveraging the temperature-dependent charge loss rate as a detection mechanism. The charge storage component's charge level serves as a parameter that changes predictably with temperature exposure. By measuring the remaining charge and comparing it to the baseline, the system detects thermal events without active power consumption. The charge loss rate acts as a natural parameter that encodes thermal history.
2Duration of action of stationary object
If the readout mechanism senses the remaining charge without substantially altering it, then the thermal history record is preserved for future readings, but the sensing mechanism must be highly precise and non-invasive
Solution Approach 1:
The patent employs an intermediary approach by using a sensing interface that couples to the charge storage component through a field effect transistor channel and gate oxide structure. This intermediary structure allows the readout mechanism to sense the remaining charge indirectly through electrical field effects rather than direct contact, minimizing charge disturbance. The FET channel acts as a mediator that translates the stored charge into a measurable signal while preserving the original charge state.
3Reliability
If the charging mechanism is disabled after placing the initial charge, then tampering to reset the charge is prevented, but the mechanism adds complexity to the sensor design
Solution Approach 1:
The patent applies the extraction principle by separating the charging function from the sensing function. The charging mechanism is designed as a distinct, disposable component that performs its function of placing the initial charge and then is effectively removed or disabled from the system. This extraction of the charging function prevents tampering while keeping the main sensor structure relatively simple and focused on detection rather than both charging and sensing.
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
Enables the detection of thermal events without requiring power, providing a passive and non-invasive means to determine if a component or device has been subjected to temperature excursions, potentially indicating tampering, and maintains a record of temperature history without alteration.
Implementation Method 1
a charge storage component configured to hold an initial charge and to lose charge at a rate dependent upon a temperature of the charge storage component
Implementation Method 2
the sensing interface includes at least one field effect transistor channel in proximity to the floating gate and coupled to the floating gate through a gate oxide
Implementation Method 3
the charging mechanism may be configured to place the initial charge on the charge storage component via at least one of Fowler-Nordheim tunneling and hot carrier injection
Data Source
AI summary
A thermal event sensor includes a charge storage component formed on a substrate, configured to hold an initial charge, and configured to lose charge at a rate dependent upon temperature. A sensing interface is coupled to the charge storage component and a readout mechanism is coupled to the sensing interface. The readout mechanism senses a remaining charge on the charge storage component and provides a readout value indicative of the remaining charge.