Wafer-Scale Free-Standing Structures via Movable Platform Ion Etching
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Solution Overview
Problem
Current methods for fabricating freestanding nanostructures from materials like diamond, lithium niobate, silicon carbide, and gallium nitride face challenges in achieving consistent geometry and uniformity due to ion damage and limitations in reproducing identical devices on a wafer scale, particularly with techniques like reactive ion etching and focused ion beam milling.
Innovation Solution
A method involving reactive ion beam etching using an ion milling system with a movable platform and resist mask to facilitate undercutting of bulk substrates, allowing for wafer-scale fabrication of free-standing mechanical and photonic structures by controlling the ion stream and platform movement to achieve uniform undercutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reactive ion etching with Faraday cage is used to create freestanding structures, then undercutting capability is improved, but ion uniformity and device consistency deteriorate
Solution Approach 1:
The patent extracts the Faraday cage from the etching chamber and replaces it with a movable platform system. This removes the source of ion non-uniformity while preserving the ability to create undercuts through controlled platform movement during etching, thereby resolving the contradiction between undercutting capability and ion uniformity
Solution Approach 2:
The patent introduces a movable platform that can be dynamically positioned during the etching process. By moving the platform at controlled speeds and angles, the system achieves uniform ion exposure across the wafer surface while still enabling undercut formation, thus improving both ion uniformity and manufacturing precision simultaneously
2Manufacturing precision
If focused ion beam milling is used to fabricate nanostructures, then device geometry precision is improved, but ion damage to device layer increases
Solution Approach 1:
The patent applies local quality by using a resist mask to selectively protect specific regions of the device layer during etching. The mask is applied only where pattern definition is needed, allowing precise geometry control in masked areas while minimizing ion exposure and damage to unmasked regions, thus resolving the contradiction between geometry precision and ion damage
Solution Approach 2:
The patent applies preliminary action by pre-coating the substrate with a resist mask before the etching process. This mask is specifically designed to protect sensitive device regions from ion damage while allowing etching in desired pattern areas, thereby achieving both geometric precision and damage minimization through advance preparation
3Ease of operation
If crystal ion-slicing is used to create freestanding structures, then mechanical freedom is improved, but ion damage to device layer increases
Solution Approach 1:
The patent introduces a resist mask as an intermediary between the ion beam and the device layer. This intermediary selectively blocks ions from reaching sensitive regions, allowing mechanical freedom to be achieved through undercutting while minimizing direct ion damage to the device layer, thus resolving the contradiction between mechanical freedom and ion damage
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 highly uniform and reproducible freestanding nanostructures across large areas, minimizing ion damage and achieving consistent device geometry, suitable for both mechanical and photonic applications.
Implementation Method 1
A resist mask is applied to a bulk substrate. The bulk substrate is attached to a movable platform. The bulk substrate is exposed to an ion stream produced by a reactive ion beam etching source.
Implementation Method 2
The bulk substrate is exposed to an ion stream produced by a reactive ion beam etching source. The platform is moved relative to the ion stream to facilitate undercutting
Data Source
AI summary
A method for fabrication of free standing mechanical and photonic structures is presented. A resist mask is applied to a bulk substrate. The bulk substrate is attached to a movable platform. The bulk substrate is exposed to an ion stream produced by a reactive ion beam etching source. The platform is moved relative to the ion stream to facilitate undercutting a portion of the bulk substrate otherwise shielded by the mask.