Wafer-Level Moisture Sensor With Shielding Elements
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Solution Overview
Problem
The production of moisture sensors for relative humidity measurement is economically challenging due to the combination of sensor structures and application-specific integrated circuits (ASICs), particularly in electronic consumer devices, where cost-effective production methods must maintain reliability and accuracy.
Innovation Solution
A method for producing a moisture sensor at the wafer level involves a substrate arrangement with a semiconductor substrate, metallization layer stack, conductive sensor structure elements, and a moisture-absorbing layer, where a planar cover layer arrangement is formed and exposed to create a moisture sensor with reduced parasitic capacitance through the use of shielding elements and sacrificial layers, allowing for efficient integration into existing semiconductor processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor structures and ASICs are combined for moisture sensing, then measurement precision is improved, but manufacturing complexity increases
Solution Approach 1:
The sensor structure is divided into separate functional elements: conductive sensor structure elements (interdigital electrodes) for capacitance measurement, insulation layers for electrical isolation, and a moisture-absorbing layer for humidity sensing. This segmentation allows each component to be optimized independently while maintaining overall measurement precision and simplifying the manufacturing process by enabling modular production steps.
Solution Approach 2:
The substrate arrangement integrates multiple functions into a single structure: the conductive sensor elements serve both as electrical connections and as part of the capacitive sensing mechanism, while the insulation layers provide both electrical isolation and structural support. This multi-functionality reduces the number of separate components needed, thereby simplifying manufacturing while maintaining measurement accuracy.
2Ease of manufacture
If conventional production methods are used, then ease of manufacture is maintained, but parasitic capacitance increases reducing measurement precision
Solution Approach 1:
Parasitic capacitance sources are extracted and isolated from the sensing structure through dedicated insulation layers positioned between the conductive sensor elements and the substrate. This extraction removes the harmful capacitive coupling while maintaining the simplicity of conventional wafer-level production methods, as the insulation layers are applied using standard deposition techniques.
Solution Approach 2:
Insulation layers serve as intermediary structures between the conductive sensor elements and the substrate, providing electrical isolation that eliminates parasitic capacitance. These intermediary layers are integrated into the production process using standard semiconductor manufacturing techniques, maintaining ease of manufacture while significantly improving measurement precision by reducing unwanted capacitive effects.
3Productivity
If wafer level production is implemented, then productivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The substrate arrangement is prepared in advance with pre-formed metallization layer stacks and insulation structures before the sensor elements are deposited. This preliminary preparation of the substrate with aligned reference structures enables subsequent layers to be deposited with accurate alignment, maintaining high manufacturing precision while benefiting from the productivity gains of wafer-level parallel processing.
Solution Approach 2:
The production process utilizes controlled deposition parameters and standardized layer thicknesses that are optimized for wafer-level processing. By establishing precise parameter ranges for layer deposition, etching, and patterning steps, the process achieves high manufacturing precision across entire wafers simultaneously, thereby improving productivity without sacrificing alignment accuracy.
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 enables the production of reliable and accurate humidity sensors that can be integrated into existing semiconductor processes, reducing production costs while maintaining sensor performance by minimizing parasitic capacitance and enhancing signal-to-noise ratio.
Implementation Method 1
applying a moisture-absorbing layer element (232) on the planar cover layer stack (220) covering the sensor structure (214)
Implementation Method 2
reducing production costs while maintaining sensor performance by minimizing parasitic capacitance and enhancing signal-to-noise ratio
Data Source
AI summary
In accordance with an embodiment, a method for producing a moisture sensor includes providing a substrate arrangement, applying a sensor structure, applying a first cover layer on the sensor structure, locally removing the planar cover layer arrangement to expose portions of an insulation layer, applying a third cover layer on the exposed portions of the insulation layer, exposing the planar cover layer arrangement covering the sensor structure, and applying a moisture-absorbing layer element on the planar cover layer arrangement covering the sensor structure to obtain the moisture sensor.