Optical Filter Channels with Monolithic Spacers for Sensor Resolution
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Solution Overview
Problem
Conventional methods for forming optical channels in optical filters result in dimensions larger than sensor elements, leading to reduced resolution and increased etch-induced defects, which negatively impact the performance of optical sensors.
Innovation Solution
The use of a monolithic spacer formed through etching with grayscale lithography, allowing for reduced critical dimensions of optical channels to match or exceed sensor element dimensions, and a single etching process to minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form optical channels, then the manufacturing process is simpler, but the critical dimension becomes larger than sensor elements causing reduced resolution
Solution Approach 1:
The optical channel formation process is segmented into multiple stages: first forming the monolithic spacer structure, then performing grayscale lithography to create the etch mask, and finally etching to define the optical channel. This segmentation allows precise control of the critical dimension at each stage while maintaining overall manufacturing feasibility.
Solution Approach 2:
The patent introduces a vertical dimension by forming a monolithic spacer with controlled thickness (first thickness) that extends above the sensor element array. This vertical structure enables precise lateral dimension control through grayscale lithography on the spacer surface, allowing the optical channel critical dimension to be independently optimized relative to the sensor element pitch.
2Reliability
If conventional etching methods are used, then the manufacturing process is faster, but etch-induced defects increase reducing reliability
Solution Approach 1:
The monolithic spacer is formed in advance as a sacrificial structure before the final optical channel etching. This preliminary structure serves as a protective and guiding element during the etching process, preventing direct exposure of the sensor element array to etch-induced defects while enabling precise critical dimension control.
Solution Approach 2:
The monolithic spacer acts as an intermediary structure between the sensor element array and the final optical channel. It provides a protected environment during manufacturing, allowing the optical channel to be formed with precise dimensions without directly exposing the sensor elements to harmful etching conditions that would cause defects.
3Measurement precision
If optical channel critical dimension is reduced to match sensor elements, then resolution improves, but manufacturing precision requirements become more stringent
Solution Approach 1:
The patent changes the thickness parameter of the monolithic spacer (first thickness) as a controllable variable. By adjusting this parameter, the optical channel critical dimension can be precisely controlled through the grayscale lithography process, enabling the optical channel to match the sensor element pitch while maintaining manufacturability through standardized fabrication techniques.
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 enhances sensor resolution by ensuring each optical channel is aligned with a single sensor element and reduces defects, thereby improving the performance of optical filters.
Implementation Method 1
the monolithic spacer may be configured to transmit greater than a threshold percentage of light that has a wavelength that is within each of the first range of the electromagnetic spectrum, the second range of the electromagnetic spectrum, the third range of the electromagnetic spectrum, and the fourth range of the electromagnetic spectrum
Implementation Method 2
the first mirror may be configured to reflect a first range of the electromagnetic spectrum; the second mirror may be configured to reflect a second range of the electromagnetic spectrum; the third mirror may be configured to reflect a third range of the electromagnetic spectrum; the fourth mirror may be configured to reflect a fourth range of the electromagnetic spectrum
Data Source
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AI summary
An optical filter includes a first optical channel that includes a first mirror and a second mirror that are configured to reflect one or more ranges of an electromagnetic spectrum, and a first portion of a monolithic spacer that is positioned between the first and second mirrors. A second optical channel includes a third mirror and a fourth mirror that are configured to reflect one or more ranges of the electromagnetic spectrum, and a second portion of the monolithic spacer that is positioned between the third and fourth mirrors. A method of manufacturing the optical filter includes forming a first plurality of mirrors; forming, on the first plurality of mirrors, a monolithic spacer; forming a multilevel etch mask on the monolithic spacer using a grayscale lithography procedure; etching the multilevel etch mask and the monolithic spacer; and forming a second plurality of mirrors on the monolithic spacer.