Micropatterned Sensor with Suspended Diaphragm for Low Noise
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Solution Overview
Problem
Existing methods for producing micropatterned sensors often fail to achieve high resolution and low noise, limiting the development of complex sensors.
Innovation Solution
The production of micropatterned sensors involves forming sensor elements suspended under a dielectric diaphragm with LOCOS reinforcements, which provides mechanical stability and thermal decoupling, allowing for low noise and high-resolution sensing. The process includes rendering a substrate region porous, growing an epitaxial layer, and patterning a dielectric layer to form a diaphragm with suspension springs for electrical lead wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional micropatterned sensor production methods are used, then manufacturing simplicity is maintained, but measurement precision and signal quality deteriorate due to high noise levels
Solution Approach 1:
The sensor structure is segmented into distinct functional regions: a detector region with sensor elements suspended in cavities, and a laterally adjacent circuit region for signal evaluation. This spatial segmentation allows the sensor elements to be thermally isolated from the substrate and circuit region, reducing noise while maintaining manufacturability through standardized production processes
Solution Approach 2:
The sensor elements are developed in an epitaxial monocrystalline layer, which provides locally superior crystalline quality and low noise characteristics. The epitaxial layer is grown only in the detector region, giving this specific area enhanced measurement precision while the rest of the chip can use standard substrate material
2Measurement precision
If sensor elements are thermally coupled to the substrate, then mechanical stability is improved, but measurement precision deteriorates due to thermal noise and interference
Solution Approach 1:
The sensor elements are extracted from direct thermal contact with the substrate by suspending them in cavities formed underneath a dielectric diaphragm. This physical separation removes the thermal coupling path that would otherwise conduct heat and noise from the substrate to the sensitive sensor elements
Solution Approach 2:
The sensor elements are positioned in a third dimension (vertically suspended in cavities) rather than being planarly mounted on the substrate surface. This vertical displacement creates thermal isolation while the diaphragm and suspension springs provide mechanical stability, resolving the contradiction between thermal decoupling and mechanical support
3Productivity
If high integration of sensor elements is achieved, then productivity increases, but device complexity increases making high resolution and low noise difficult to achieve
Solution Approach 1:
The detector region and circuit region are merged into a single integrated chip structure, with the circuit region laterally adjacent to the detector region. This allows high integration and productivity while maintaining measurement precision through the thermal isolation provided by the cavity suspension structure
Solution Approach 2:
A dielectric layer with LOCOS reinforcements acts as an intermediary structure between the sensor elements and the substrate/circuit region. This intermediate diaphragm structure provides thermal isolation while allowing mechanical stability and electrical lead wire routing, enabling high integration without sacrificing noise performance
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 creation of a high-resolution, low-noise sensor array with excellent thermal decoupling, suitable for applications like temperature measurement and gas concentration spectroscopy, while allowing for rapid and cost-effective production of a combined sensor and electronic evaluation circuit on a single chip.
Implementation Method 1
The porosified region is relocated into a cavity by a subsequent thermal treatment
Implementation Method 2
growing an epitaxial layer
Implementation Method 3
The diaphragm may be patterned such that it forms individual suspension springs, which link each sensor element to the surrounding mainland
Implementation Method 4
LOCOS (local oxidation of silicon) reinforcements produced by local oxidation
Data Source
AI summary
A sensor, in particular for the spatially resolved detection, includes a substrate, at least one micropatterned sensor element having an electric characteristic whose value varies as a function of the temperature, and at least one diaphragm above a cavity, the sensor element being disposed on the underside of the at least one diaphragm, and the sensor element being contacted via connecting lines, which extend within, on top of or underneath the diaphragm. In particular, a plurality of sensor elements may be formed as diode pixels within a monocrystalline layer formed by epitaxy. Suspension springs, which accommodate the individual sensor elements in elastic and insulating fashion, may be formed within the diaphragm.