Co-Integrated Absolute and Relative Pressure Sensors on Single Wafer
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Solution Overview
Problem
Current technologies fail to simultaneously manufacture absolute and relative pressure sensors with matched performance on the same die, requiring separate processes and components for each type of sensor.
Innovation Solution
A method involving deep reactive-ion etching to create shallow and deep cavities in a wafer, allowing for the co-integration of absolute and relative pressure sensors with matched temperature characteristics and membrane thickness, enabling simultaneous measurement of both types of pressure using a single process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate manufacturing processes are used for absolute and relative pressure sensors, then each sensor type can be optimized independently, but manufacturing efficiency decreases and device complexity increases
Solution Approach 1:
The patent combines both absolute and relative pressure sensor manufacturing into a single integrated process. The method etches both shallow and deep cavities in the same base wafer, bonds the same top wafer to both cavities, and performs back thinning to create both sensor types simultaneously. This merging eliminates the need for separate manufacturing processes while ensuring matched performance characteristics between the two sensor types.
2Adaptability or versatility
If separate manufacturing processes are used for absolute and relative pressure sensors, then process flexibility is maintained, but device complexity and component requirements increase
Solution Approach 1:
The patent employs universal manufacturing steps that serve both absolute and relative sensor fabrication. The same base wafer, top wafer, bonding process, and back thinning process are used for both sensor types. The only differentiation is the cavity depth, which is controlled by etching parameters. This universal approach reduces device complexity while maintaining the ability to manufacture both sensor types on the same die.
3Reliability
If different manufacturing processes are used for absolute and relative pressure sensors, then each sensor can be optimized for its specific function, but temperature characteristics and membrane thickness matching become difficult
Solution Approach 1:
The patent merges the manufacturing processes for both sensor types, ensuring they undergo identical thermal and mechanical processing steps. Since both sensors are fabricated on the same wafers through the same bonding and back thinning processes, they inherently exhibit matched temperature characteristics and membrane thicknesses. This eliminates the difficulty of matching parameters that would arise from separate manufacturing 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
Enables efficient manufacturing of sensors with matched performance for both absolute and relative pressure measurements, allowing for robust and accurate pressure sensing in various environments without the need for interconnects, and facilitating the creation of small, high-performance sensors with optimized linearity.
Implementation Method 1
Piezo resistive materials have the ability to convert mechanical stress into a change of electrical properties. The pressure on the semiconductor membrane causes the surface stress on the semiconductor material changes the resistance value.
Data Source
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AI summary
A method (100) for manufacturing a system (200) in a wafer (210) for measuring an absolute and a relative pressure. In a first step (110) a shallow (220) and a deep (230) cavity are etched in the wafer (210). In a second step (120) a top wafer (510) is applied and in a third step (125) the top wafer is thinned for forming a first respectively second membrane (262, 272) over the shallow respectively deep cavity (220, 230), and for forming in the top wafer (510) first respectively second bondpads (261, 271) at the first respectively second membrane (262, 272) resulting in a first respectively second sensor (260, 270). A third step (130) back grinding the wafer (210) resulting in a opened deep cavity (230) and a still closed shallow cavity (220). The first bondpads (261) of the first sensor (260) for measuring an absolute pressure and the second bondpads (271) of the second sensor (270) a relative pressure. The etching in the first step defines the edges of the first membrane and of the second membrane in respectively the sensors formed from the shallow and the deep cavity.