Optical Filter Manufacturing with Uniform Mirrors and Nonlinear Spacers
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Solution Overview
Problem
Conventional deposition processes struggle to form optical filters with uniform mirrors and spacers having non-linear thickness profiles, leading to inconsistent spectral filtering performance and significant material waste due to annular arrangements on wafers.
Innovation Solution
A manufacturing process using sputtering for uniform mirrors and grayscale lithography for spacers with non-linear thickness profiles, enabling consistent spectral filtering performance and efficient use of wafer surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition processes are used to form optical filters, then the manufacturing process is simple, but the mirrors and spacers cannot achieve uniform and non-linear thickness profiles, leading to inconsistent spectral filtering performance
Solution Approach 1:
A mandrel structure is formed beforehand with the desired non-linear thickness profile. The spacer material is then deposited conformally on this mandrel, automatically acquiring the precise non-linear thickness profile through the preliminary structuring action. This resolves the contradiction by preparing the complex geometry in advance, allowing simple conformal deposition to achieve high precision.
Solution Approach 2:
A mandrel structure serves as an intermediary object that imparts the desired non-linear thickness profile to the spacer. The mandrel acts as a template or mediator between the deposition process and the final spacer geometry, enabling conventional deposition techniques to produce complex profiles without direct complex control.
2Loss of substance
If annular arrangements are used on wafers, then the deposition process can be simplified, but significant material waste occurs
Solution Approach 1:
The design transitions from conventional annular (circular) arrangements to rectangular or square-shaped optical filters that can be packed in a grid pattern on the wafer. This dimensional change in the footprint geometry enables more efficient space utilization and reduces the gaps between devices, thereby reducing material waste while maintaining manufacturing simplicity.
3Reliability
If spacers with non-linear thickness profiles are formed using conventional processes, then the device complexity is reduced, but the spectral filtering performance becomes inconsistent
Solution Approach 1:
The mandrel is pre-formed with the exact non-linear thickness profile required for the desired spectral filtering performance. This preliminary action ensures that when spacer material is deposited conformally, the precise profile is automatically transferred, achieving consistent and reliable spectral filtering without complex in-situ profile control during deposition.
Solution Approach 2:
The mandrel's physical geometry parameters (thickness profile) are specifically designed and controlled to match the desired spectral filtering characteristics. By changing and optimizing the mandrel's dimensional parameters beforehand, the spacer inherits these precise parameters, ensuring consistent spectral performance while avoiding complex real-time control during deposition.
4Manufacturing precision
If uniform thickness profiles are used for simplicity, then the manufacturing process is easier, but optical smile and reduced finesse occur
Solution Approach 1:
The mandrel is pre-shaped with the specific non-linear thickness profile needed to achieve the desired optical performance characteristics (reduced optical smile, improved finesse). This preliminary structuring allows the spacer to inherit the precise profile through simple conformal deposition, achieving high optical precision without complex deposition control.
Solution Approach 2:
The mandrel acts as an intermediary that translates the desired optical performance requirements into physical thickness profile geometry. By controlling the mandrel's shape, the system achieves precise optical performance (reduced smile, improved finesse) while keeping the deposition process simple and straightforward.
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 allows for optical filters with reduced optical smile and improved finesse, selectivity, and consistent performance across widths, utilizing wafer surface more efficiently.
Implementation Method 1
A manufacturing process using sputtering for uniform mirrors
Implementation Method 2
grayscale lithography for spacers with non-linear thickness profiles
Data Source
AI summary
A method of manufacturing an optical filter that includes a first mirror that has a first uniform thickness, a second mirror that has a second uniform thickness, and a spacer that is positioned between the first mirror and the second mirror. The spacer has a variable thickness along a first axis of the optical filter. In some implementations, a thickness profile of the spacer, along the first axis, includes one or more portions that have a non-linear slope with an absolute value that is greater than zero.