RIE Etching of WSi2/Si Multilayers for Laue Lenses
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Solution Overview
Problem
Current techniques for sectioning multilayer Laue lenses are labor-intensive and prone to delamination or structure damage, limiting the yield and flexibility of optics fabrication, and existing reactive ion etching recipes are limited for concurrent etching of multiple elements and complex shapes.
Innovation Solution
A process using Reactive Ion Etching (RIE) with fluorine-based and chlorine-based chemistries, either alone or in combination with Inductively Coupled Plasma (ICP), to achieve high anisotropy, deep etching, and smooth sidewalls for monolayer and multilayer materials, such as WSi2/Si, enabling the production of advanced optics with improved stability and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical sectioning and polishing techniques are used to section multilayer Laue lenses, then the optics can be fabricated, but the process is labor-intensive and prone to delamination or structure damage, reducing yield
Solution Approach 1:
The patent replaces mechanical sectioning and polishing techniques with reactive ion etching (RIE), a plasma-based process that uses chemical reactions and ion bombardment to remove material. This substitution eliminates mechanical contact that causes delamination and structure damage, thereby improving structural integrity while maintaining manufacturability
Solution Approach 2:
The patent employs specific RIE parameters including fluorine-based chemistry (SF6), controlled pressure (10-100 mTorr), and optimized RF power to achieve high anisotropy and deep etching without mechanical damage. These parameter changes enable a non-mechanical process that preserves structural integrity
2Adaptability or versatility
If traditional RIE recipes are used for etching, then the process is simple, but they are limited for concurrent etching of multiple elements and complex shapes
Solution Approach 1:
The patent develops a universal RIE process using fluorine-based chemistry that can concurrently etch multiple elements (silicon, tungsten silicide, and other materials) with a single recipe. This multi-functional approach eliminates the need for multiple specialized etching steps, enhancing adaptability while maintaining process simplicity
Solution Approach 2:
The patent uses composite plasma chemistry (SF6/O2 mixtures) that provides both fluorine for etching and oxygen for passivation, enabling simultaneous processing of different materials with distinct etching requirements. This composite approach achieves versatility across multiple elements without significantly increasing process complexity
3Manufacturing precision
If deep etching is performed to achieve high aspect ratios, then the optics performance improves, but the risk of delamination and structure damage increases
Solution Approach 1:
The patent replaces mechanical polishing with RIE to achieve deep etching and high aspect ratios without mechanical stress that causes delamination. The plasma-based process enables precise removal of material to deep depths while maintaining structural integrity through controlled chemical reactions
Solution Approach 2:
The patent optimizes RIE parameters including pressure (10-100 mTorr), RF power, and gas flow rates to achieve high anisotropy and deep etching profiles. These parameter changes enable controlled deep etching that maintains vertical sidewalls and prevents delamination, achieving both high aspect ratio and structural integrity
4Manufacturing precision
If multi-step etching processes are used to improve anisotropy, then the sidewall profile improves, but the process becomes more complex and time-consuming
Solution Approach 1:
The patent achieves high anisotropy and smooth sidewall profiles in a single RIE step using fluorine-based chemistry with optimized parameters. This single-step process performs multiple functions (etching, passivation, and profile control) simultaneously, eliminating the need for multiple sequential steps and reducing process time
Solution Approach 2:
The patent uses specific RIE parameters including SF6/O2 chemistry ratios, pressure (10-100 mTorr), and RF power optimization to achieve high anisotropy and smooth sidewalls in one step. These parameter changes enable a single process step to accomplish what traditionally required multiple steps, reducing time while maintaining precision
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
The process achieves high anisotropy and deep etching with smooth sidewalls, reducing mechanical damage and increasing the yield of optics fabrication, allowing for the production of complex structures like multilayer Laue lenses and other nanostructures with enhanced performance.
Implementation Method 1
reactive ion etching with a combination of fluorine-based and chlorine chemistry
Implementation Method 2
reactive ion etching (RIE)
Data Source
AI summary
A process is disclosed for sectioning by etching of monolayers and multilayers using an RIE technique with fluorine-based chemistry. In one embodiment, the process uses Reactive Ion Etching (RIE) alone or in combination with Inductively Coupled Plasma (ICP) using fluorine-based chemistry alone and using sufficient power to provide high ion energy to increase the etching rate and to obtain deeper anisotropic etching. In a second embodiment, a process is provided for sectioning of WSi2/Si multilayers using RIE in combination with ICP using a combination of fluorine-based and chlorine-based chemistries and using RF power and ICP power. According to the second embodiment, a high level of vertical anisotropy is achieved by a ratio of three gases; namely, CHF3, Cl2, and O2 with RF and ICP. Additionally, in conjunction with the second embodiment, a passivation layer can be formed on the surface of the multilayer which aids in anisotropic profile generation.