IR Sensor Pixel Pairing for Pressure-Independent Sensing
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Solution Overview
Problem
Existing infrared (IR) sensors face challenges in maintaining sensitivity and stability due to pressure variations within the cavity, which affect the accuracy of IR radiation measurement, particularly in semiconductor devices using MEMS structures.
Innovation Solution
A semiconductor device with at least one sensor pixel and one reference pixel in the same cavity at sub-atmospheric pressure, where both pixels experience the same gas pressure, allowing active heating to maintain their temperatures equal, enabling the difference in heating powers to determine incident IR radiation independently of cavity pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor operates at sub-atmospheric pressure to maximize sensitivity, then the sensitivity is improved, but the measurement becomes dependent on pressure variations which reduces stability
Solution Approach 1:
The device is divided into two separate pixels: a sensor pixel that detects IR radiation and a reference pixel that does not. Both pixels experience the same pressure variations, allowing the reference pixel to serve as a baseline for compensating pressure-dependent effects in the sensor pixel.
Solution Approach 2:
The reference pixel acts as an intermediary element that experiences the same environmental conditions (including pressure variations) as the sensor pixel but without the IR radiation signal. This allows the pressure effects to be measured and subtracted from the sensor signal.
2Measurement precision
If pressure variations are compensated using calibration curves, then measurement accuracy is improved, but device complexity and manufacturing precision requirements increase
Solution Approach 1:
The reference pixel enables the system to self-compensate for pressure variations in real-time without requiring external calibration curves or complex pressure sensing mechanisms. The reference pixel automatically provides the baseline needed to correct pressure-dependent drift.
3Device complexity
If the same pixel is used for both sensing and reference, then device complexity is reduced, but measurement precision deteriorates due to cross-contamination of signals
Solution Approach 1:
The device uses two spatially separated pixels: one dedicated to sensing IR radiation and another dedicated to reference measurements. This segmentation allows each pixel to perform its specific function without signal contamination while maintaining comparable thermal and pressure conditions.
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 enhances the reliability and longevity of IR sensors by eliminating pressure-dependent variations and simplifying signal determination, improving linearity and accuracy without the need for explicit pressure compensation or calibration curves.
Implementation Method 1
a first heater for increasing a temperature of the first absorber when a first power is applied to the first heater
Implementation Method 2
a second heater for increasing a temperature of the second absorber when a second power is applied to the second heater
Implementation Method 3
a first absorber arranged for receiving said IR radiation
Implementation Method 4
first temperature measurement means for measuring the temperature of the first absorber; second temperature measurement means for measuring the temperature of the second absorber
Implementation Method 5
a control circuit adapted for measuring the first temperature and the second temperature and for generating and applying the first power to the first heater and for generating and applying the second power to the second heater in such a way that the first temperature is substantially equal to the second temperature
Data Source
AI summary
A semiconductor device for measuring IR radiation is disclosed. It comprises a substrate and a cap enclosing a cavity, a sensor pixel in the cavity, comprising a first absorber for receiving said IR radiation, a first heater, first temperature measurement means for measuring a first temperature; a reference pixel in the same cavity, comprising a second absorber shielded from said IR radiation, a second heater, and second temperature measurement means for measuring a second temperature; a control circuit for applying a first/second power to the first/second heater such that the first temperature equals the second temperature; and an output circuit for generating an output signal indicative of the IR radiation based on a difference between the first and second power.