Thermal Sensor Getter Material Vacuum Stability
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Solution Overview
Problem
Current 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 the two wafers together, then manufacturing cost is reduced, but the vacuum level in the chambers deteriorates due to significant outgassing from the glass frit
Solution Approach 1:
The patent extracts and removes gas molecules from the chamber environment by incorporating a getter material that actively sorbs outgassed molecules. This separates the harmful outgassing effect from the chamber atmosphere, allowing glass frit bonding to be used while maintaining vacuum quality.
Solution Approach 2:
The getter material acts as an intermediary substance between the outgassing glass frit and the chamber atmosphere. It absorbs the harmful outgassed molecules, preventing them from degrading the vacuum level, thus mediating between the low-cost bonding process and the required vacuum stability.
2Reliability
If the chambers are backfilled with a predetermined gas at pressure greater than 10 mbar, then the effect of outgassing on responsivity is reduced, but responsivity still drifts over the lifetime of the thermal sensor elements due to outgassing and out-diffusion
Solution Approach 1:
The getter material continuously removes outgassed molecules from the backfilled gas atmosphere, maintaining the gas composition stability over time. This extraction of harmful molecules prevents the gradual degradation of responsivity that would otherwise occur during the device lifetime.
Solution Approach 2:
The getter material provides continuous active sorption of outgassed molecules throughout the device lifetime, ensuring ongoing maintenance of gas composition stability and responsivity, rather than a one-time fix.
3Reliability
If a deep vacuum (less than 1 mbar) is maintained in the chambers, then thermal sensor performance is optimized, but this requires expensive hermetic sealing processes that prevent future outgassing
Solution Approach 1:
The patent converts the harmful outgassing effect into a manageable phenomenon by using a getter material that actively sorbs the outgassed molecules. This allows the use of inexpensive glass frit bonding while still achieving and maintaining deep vacuum conditions through the getter's continuous purification action.
Solution Approach 2:
The invention changes the approach from preventing outgassing through expensive hermetic sealing to actively managing the gas composition through getter material sorption. This parameter change in the vacuum maintenance strategy enables the use of lower-cost bonding processes.
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, as the getter material effectively sorbs hydrogen and other gases, minimizing their influence on thermal conductivity.
Implementation Method 1
the getter material effectively sorbs hydrogen and other gases, minimizing their influence on thermal conductivity
Implementation Method 2
thermally bonding the first part of the body to the second part of the body so as to seal hermetically the chamber
Data Source
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).