AlN Layer Vertical Flank Etching via Substrate Topology
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Solution Overview
Problem
Current techniques for etching Aluminum Nitride (AlN) materials result in isotropic etching, leading to flanks that are not vertically oriented, which is a challenge for producing MEMS components, acoustic resonators, and other devices requiring straight, perpendicular flanks.
Innovation Solution
A method involving substrate topology formation through etching to create a step-type pattern, followed by AlN layer deposition and wet etching using a mask layer to achieve flanks substantially perpendicular to the substrate surface, allowing for the production of vertical or inclined flanks with precise alignment and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry or wet etching techniques are used to etch AlN, then the etching process is simple and widely applicable, but the flanks are not vertical due to isotropic etching character
Solution Approach 1:
The substrate surface is pre-etched to create a step-type pattern with vertical flanks before AlN deposition. This preliminary topography preparation ensures that subsequent AlN layer deposition and etching will produce vertical flanks, as the etching process follows the pre-established vertical references from the substrate steps.
Solution Approach 2:
The invention transitions from conventional planar etching to three-dimensional etching by utilizing substrate steps. The step-type pattern creates vertical reference surfaces that guide the etching process, transforming the etching from a two-dimensional surface process to a three-dimensional process that exploits vertical geometry to achieve vertical flanks.
2Manufacturing precision
If conventional etching is used, then the process is straightforward, but it cannot produce the straight flanks required for MEMS components and resonators
Solution Approach 1:
The substrate surface is pre-etched to create a step-type pattern with vertical flanks before AlN deposition. This preliminary topography preparation ensures that subsequent AlN layer deposition and etching will produce vertical flanks, as the etching process follows the pre-established vertical references from the substrate steps.
Solution Approach 2:
The invention transitions from conventional planar etching to three-dimensional etching by utilizing substrate steps. The step-type pattern creates vertical reference surfaces that guide the etching process, transforming the etching from a two-dimensional surface process to a three-dimensional process that exploits vertical geometry to achieve vertical flanks.
3Manufacturing precision
If isotropic etching is used, then the etching process is simple and uniform, but it etches in both vertical and horizontal directions resulting in non-vertical flanks
Solution Approach 1:
The substrate surface is pre-etched to create a step-type pattern with vertical flanks before AlN deposition. This preliminary topography preparation ensures that subsequent AlN layer deposition and etching will produce vertical flanks, as the etching process follows the pre-established vertical references from the substrate steps.
Solution Approach 2:
The invention transitions from conventional planar etching to three-dimensional etching by utilizing substrate steps. The step-type pattern creates vertical reference surfaces that guide the etching process, transforming the etching from a two-dimensional surface process to a three-dimensional process that exploits vertical geometry to achieve vertical flanks.
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 enables the creation of AlN layers with vertical or inclined flanks, facilitating the production of MEMS components and resonators with precise geometry, preventing parasitic wave propagation and enabling fine gap capabilities.
Implementation Method 1
The topology can result from an etching of the surface of the substrate so as to obtain at least the step type pattern
Implementation Method 2
The deposition of the AlN layer is carried out on the raised part and on the lower level
Implementation Method 3
The etching of the AIN layer is of the wet etching type
Data Source
AI summary
The invention relates to a method for producing an AlN layer with substantially vertical flanks relative to a surface (2') of a substrate (2), each flank extending between a lower end and an upper end, the surface of said substrate having a topology (4, 4', 4a, 4'a, 4b), comprising at least one step-type pattern (10, 12, 14, 16), this method comprising: - depositing the AlN layer (31), at least on said pattern of the topology, the upper end of the step corresponding to the lower end of said flank, - forming, over the AlN layer, a mask layer (40, 40'), at least one edge of which is positioned so as to define the upper end of the flank, - etching the AlN layer (31) through the mask, to obtain said flank, the slope of the flank being defined by the position of said upper and lower ends along a plane substantially perpendicular to the substrate surface.