Sensor Device Fabrication via Backside Etching and Sacrificial Layer
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Solution Overview
Problem
Existing sensor device fabrication methods for measuring humidity or other parameters are complex and inefficient, particularly in creating the sensing cavity between electrodes, which hinders the simplicity and speed of the process.
Innovation Solution
A method involving a substrate with a structured protection layer and a stack of dielectric and conducting layers, where a sacrificial layer is placed between the electrodes, allowing for the creation of a sensing cavity by etching from the back side of the substrate, using deep reactive-ion etching or other etching processes, to form a capacitor structure that can measure changes in dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensing cavity is created by etching after electrode deposition, then the electrode structure can be formed first, but the fabrication process becomes complex and time-consuming with multiple separate steps
Solution Approach 1:
The patent merges the electrode deposition step and the sensing cavity formation step into a single simultaneous process. The electrodes and sensing cavity are created in the same etching cycle, eliminating the need for separate deposition and etching steps. This is achieved by using a sacrificial layer that defines the cavity shape, which is removed during the electrode deposition process, thereby combining two previously separate fabrication operations into one unified step.
Solution Approach 2:
The patent applies preliminary action by depositing the sacrificial layer before electrode formation. This sacrificial layer pre-defines the sensing cavity geometry and position, allowing the electrodes to be deposited directly onto it. The sacrificial layer is then removed in-situ during the same process, eliminating subsequent separate cavity formation steps and simplifying the overall fabrication sequence.
2Productivity
If the sensing cavity is etched after electrode deposition, then the electrodes can be formed, but the process time increases due to sequential steps
Solution Approach 1:
The patent combines electrode deposition and sensing cavity formation into a single simultaneous process step. By using a sacrificial layer that is removed during the deposition process itself, the method eliminates the sequential nature of traditional fabrication where electrodes are deposited first and then the cavity is etched separately. This merging of operations directly reduces total process time and increases fabrication productivity.
Solution Approach 2:
The patent maintains continuous useful action throughout the fabrication process by ensuring that the sacrificial layer removal occurs continuously during electrode deposition without interrupting the process flow. This continuous action eliminates idle time between deposition and cavity formation steps, maximizing productivity and minimizing total fabrication time.
3Manufacturing precision
If the sacrificial layer is removed during etching, then the sensing cavity is formed, but there is a risk of electrode damage without proper protection
Solution Approach 1:
The patent uses a sacrificial layer as an intermediary element that temporarily occupies the space where the sensing cavity will eventually form. This sacrificial layer protects the electrode structure during fabrication by providing a defined boundary, and is subsequently removed to create the cavity. The intermediary sacrificial layer ensures precise cavity formation while maintaining electrode integrity throughout the process.
Solution Approach 2:
The patent applies preliminary anti-action by using the sacrificial layer to prevent unwanted etching or damage to the electrodes during the cavity formation process. The sacrificial layer acts as a protective barrier that defines the cavity boundaries and prevents the etching process from affecting the electrodes, thereby ensuring both precision and reliability.
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 method simplifies the fabrication process, protects the electrodes during etching, and enables faster creation of sensing cavities, enhancing the sensitivity and efficiency of the sensor device by allowing simultaneous revelation of the sensing structure and cavity formation.
Implementation Method 1
generating from the back side of the substrate, in a process step iv), an opening, the opening extending through the substrate from its back side to its front side and the opening removing at least part of the sacrificial layer, thereby creating a sensing cavity extending between the first electrode and the second electrode, wherein the first protection layer protects the first and second electrodes from being removed during the process step iv)
Implementation Method 2
using deep reactive-ion etching or other etching processes, to form a capacitor structure
Data Source
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AI summary
A method for fabrication of a sensor device (1) for measuring a parameter of a test substance, comprising: i) providing a substrate; ii) arranging on its front side a structured first protection layer (2); iii) arranging on the substrate with the structured first protection layer (2) a stack including first and second electrodes (3,4), a sacrificial layer between the first and second electrodes (3,4); and iv) etching in an etching step from the back side through the substrate such as to remove material of the semiconductor substrate and the sacrificial layer. The present invention also relates to such a sensor device (1).