Thermal Sensor Chamber Sealing for Stable Responsivity
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Solution Overview
Problem
Thermal sensor devices face instability in responsivity over their lifetime due to outgassing and out-diffusion of molecules during the bonding process, especially when using cost-effective glass frit bonding, which makes it difficult to maintain a deep vacuum and results in sensitivity drift.
Innovation Solution
Incorporating a getter material, such as titanium, within the thermal sensor device's chambers, which are backfilled with a gas at pressures greater than 10 mbar, and thermally bonding using glass frit bonding at an activation temperature of the getter material to create a hermetic seal and reduce molecular impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If glass frit bonding is used to bond wafers, then manufacturing cost is reduced, but vacuum level deteriorates due to significant outgassing
Solution Approach 1:
The chambers are backfilled with a predetermined gas (such as nitrogen or argon) to a pressure greater than 10 mbar before the glass frit bonding process. This preliminary backfilling action ensures that when outgassing occurs during bonding, the pressure increase is limited and does not compromise the vacuum quality significantly, thus allowing the use of cost-effective glass frit bonding while maintaining acceptable vacuum levels.
2Ease of manufacture
If glass frit bonding is used, then manufacturing cost is reduced, but responsivity stability deteriorates over device lifetime
Solution Approach 1:
The chambers are backfilled with an inert gas (such as nitrogen or argon) to create an inert atmosphere that displaces residual air and prevents out-diffusion of molecules from the chamber interior to the wafer materials over time. This inert environment maintains stable gas composition and prevents responsivity drift, allowing long-term stability even with glass frit bonding.
3Stability of the object's composition
If deep vacuum is maintained, then responsivity stability is improved, but manufacturing complexity increases due to expensive bonding processes
Solution Approach 1:
The patent changes the pressure parameter of the gas environment in the chambers from deep vacuum (less than 1 mbar) to a higher pressure (greater than 10 mbar) backfilled with inert gas. This parameter change allows the use of simpler, less expensive glass frit bonding processes while maintaining responsivity stability through the inert atmosphere that prevents molecular out-diffusion and composition changes over time.
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 immunity to responsivity drift and reduces manufacturing costs while maintaining stability by effectively managing gas composition changes within the chambers.
Implementation Method 1
disposing a getter material in the first part of the body of the sensor
Implementation Method 2
backfilling the chamber with a gas to a pressure greater than 10 mbar
Implementation Method 3
thermally bonding the first part of the body to the second part of the body so as to seal hermetically the chamber
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A method of manufacturing a thermal sensor (106) comprises providing a first part (102) of a body of the sensor (106), the first part (102) of the body being configured to define a first part (114) of a chamber (310). A second part (104) of the body of the sensor (106) is also provided, the second part (104) of the body being configured to define a second part (118) of the chamber (310). A getter material (112) is disposed in the first part (114) of the body of the sensor (106), and the first part (102) and the second part (104) of the body of the sensor (106) are brought together so that the first and second parts (102, 104) of the chamber (310) define the chamber (310). The chamber (310) is backfilled with a gas to a pressure greater than 10 mbar, and the first part (102) of the body is bonded to the second part (104) of the body so as to seal hermetically the chamber (310).