Micromechanical Component Thin-Layer Capping via SiOx Sacrificial Etching
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Solution Overview
Problem
Existing methods for manufacturing micromechanical components with thin-layer capping face challenges in achieving large and small gap widths efficiently, often requiring additional sacrificial layers and lengthy processing times, especially when dealing with thick oxide layers that are difficult to etch.
Innovation Solution
A combined silicon/silicon oxide sacrificial layer process is employed, allowing for the use of existing layers as sacrificial material and reducing the need for additional layers like SiGe, with ClF3 etching for short processing times, and a minimal protective thermal oxidation step for functional layer protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If thick oxide layers are used as sacrificial layers, then large gap widths can be achieved, but etching time increases significantly
Solution Approach 1:
The patent changes the material composition of the sacrificial layer from pure oxide to a composite silicon-oxide layer with controlled silicon content (30-70 at%). This parameter change enables the sacrificial layer to be etched rapidly by ClF3 while maintaining the ability to form large gap widths, thus resolving the contradiction between gap width and etching time
Solution Approach 2:
The silicon-oxide sacrificial layer acts as an intermediary material that combines the advantages of both silicon (rapid ClF3 etching) and oxide (large gap formation capability). This intermediary material enables both large gap widths and short etching times by providing a composition that is selectively etchable by ClF3
2Length of stationary object
If additional sacrificial layers like SiGe are deposited, then large gap widths can be achieved, but device complexity increases
Solution Approach 1:
The silicon-oxide sacrificial layer serves multiple functions: it acts as a sacrificial material for gap formation, provides a selective etching target for ClF3, and can be integrated with existing functional layers. This multi-functionality eliminates the need for additional specialized sacrificial layers like SiGe, reducing device complexity while achieving large gap widths
Solution Approach 2:
The patent merges the sacrificial layer function with existing silicon-containing layers in the device structure. By utilizing layers that already contain silicon and oxide components, the invention eliminates the need for separate additional sacrificial layers, thereby reducing the total number of layers and simplifying the device structure
3Device complexity
If existing layers are used as sacrificial layers, then the number of additional layers is reduced, but protection of functional layers becomes more challenging
Solution Approach 1:
The patent applies local quality by creating a silicon-oxide sacrificial layer with specific compositional characteristics (30-70 at% silicon) that provide selective etchability. This local compositional adjustment ensures that the sacrificial layer can be selectively removed by ClF3 while functional layers remain protected, resolving the contradiction between using existing layers and protecting functional layers
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 integrated and efficient manufacturing of micromechanical components with varying gap widths, reducing processing time and eliminating the need for thick sacrificial layers, while ensuring quick etching and effective sealing of structures.
Implementation Method 1
very short etching times, using ClF3, for example
Implementation Method 2
only one additional oxidation, for example thermal oxidation, of small layer thickness is required as a protective layer
Data Source
AI summary
A manufacturing method for a micromechanical component having a thin-layer capping. The method includes the following: forming a functional layer on a substrate; structuring the functional layer in first cutout regions having a first width and in regions of the functional layer to be removed having a second width, the second width being substantially greater than the first width; forming a first oxide layer on the structured functional layer; forming a first sealing layer on the thermally oxidized and structured functional layer, the first cutout regions having the first width being sealed; forming a cap layer on the first sealing layer; forming first through holes which extend through the cap layer, the first sealing layer, and the first oxide layer for at least partially exposing the regions of the functional layer to be removed; and selectively removing the regions of the functional layer to be removed, by introducing a first etching medium through the first through holes, resulting in second cutout regions in the functional layer which have the second width.