Incident Light Angle Detector Using Interlayer Optical Path
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Solution Overview
Problem
Existing angle of incidence detectors have undesirable fabrication costs, size constraints, and measurement resolution issues due to separate formation of shadow masks and photodetector elements, which limits their applicability in various optical systems.
Innovation Solution
A detector configuration with multiple mask layers forming an interlayer optical path that includes holes to selectively transmit radiation to a photodetector, providing improved angular selectivity and sensitivity, and allowing the photodetectors to be economically formed during the same process steps as other circuit elements, thereby reducing fabrication constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If shadow masks are formed separately from photodetector elements, then fabrication flexibility is improved, but fabrication cost and device complexity increase
Solution Approach 1:
The patent combines the shadow mask structure and photodetector elements into a single integrated device. The shadow mask is formed as part of the photodetector array fabrication process, eliminating the need for separate mask formation steps. This integration reduces device complexity while maintaining fabrication flexibility, as both components are created together in the same manufacturing sequence.
Solution Approach 2:
The patent creates a multi-functional structure where the same fabrication process produces both the photodetector elements and the shadow mask pattern. The shadow mask serves dual purposes: defining the optical path geometry and acting as a structural component of the detector array, thereby reducing overall device complexity while preserving manufacturing adaptability.
2Ease of manufacture
If shadow masks are formed separately from photodetector elements, then fabrication flexibility is improved, but fabrication cost increases
Solution Approach 1:
The patent merges the shadow mask formation with the photodetector fabrication into a single integrated process. By forming both structures simultaneously using the same semiconductor manufacturing techniques, the patent eliminates redundant fabrication steps and material deposition processes, thereby reducing fabrication cost while maintaining the flexibility to adjust optical path geometry during the unified manufacturing sequence.
3Measurement precision
If interlayer optical path with offset holes is used, then angular selectivity is improved, but measurement precision requirements increase
Solution Approach 1:
The patent employs asymmetric offset positioning of holes in different mask layers to create directional sensitivity. The holes in upper and lower masks are deliberately misaligned to define a specific optical path angle, providing improved angular selectivity. The asymmetric geometry translates angular deviations into measurable signal changes, enhancing measurement precision while the fabrication process accommodates the required precision through standard photolithographic alignment 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 configuration enhances the ability to determine the direction of incident light with improved sensitivity and selectivity, ensuring proper alignment in optical systems for accurate and energy-efficient measurements, particularly in metrology instruments with micron or sub-micron resolution.
Implementation Method 1
a photodetector... wherein the amount of signal from the photodetector is greatest when the direction of illumination approximately coincides with the nominal peak signal direction
Data Source
AI summary
A detector configuration determines the direction of illumination incident on a photosensitive device. Multiple mask layers include holes which form an interlayer optical path through which radiation reaches a photodetector. The interlayer optical path provides a selected nominal maximum signal angle and the detector senses when radiation is received at or near that angle. In one embodiment, three holes in three metallization layers provide an arbitrarily narrow interlayer optical path with improved angular detection relative to that provided by two holes. An illumination direction-sensing array may use multiple instances of the detector configuration. The detector configuration may provide enhanced utility and economy by being adapted to use only those fabrication steps used for fabricating other primary circuits on an IC.