Integrated Spectral Filter with Etch Stop Cavities for Miniaturized Image Sensors
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Solution Overview
Problem
Conventional image sensors with spectral filters are bulky and heavy, hindering miniaturization efforts, as they integrate optical elements and circuits separately rather than on a single semiconductor chip.
Innovation Solution
A spectral filter design featuring multiple reflective layers and cavities with varying thicknesses, including etch stop layers and dielectric layers, arranged in a two-dimensional manner to achieve miniaturization while maintaining optical functionality, and a method for manufacturing this filter involving specific layer deposition and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional spectral filters with separate optical elements and circuits are used, then optical functionality is maintained, but device size and weight increase
Solution Approach 1:
The patent combines multiple optical elements (reflective layers, cavities, dielectric layers) into a single integrated spectral filter structure fabricated on a semiconductor chip. This merging of previously separate optical components enables miniaturization while maintaining the complete spectral filtering functionality through the integrated Fabry-Perot resonator structure.
Solution Approach 2:
The patent transitions from bulky three-dimensional optical assemblies to a planar two-dimensional semiconductor chip structure. By arranging reflective layers, cavities, and dielectric layers in stacked two-dimensional layers on a chip substrate, the design achieves miniaturization in the vertical dimension while maintaining optical performance through the layered planar architecture.
2Manufacturing precision
If cavity thicknesses are varied to achieve different center wavelengths, then spectral selectivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates etch stop layers at predetermined positions within the cavity structure before the final etching process. These pre-positioned etch stop layers serve as reference markers that guide the etching depth to achieve precise cavity thicknesses corresponding to different center wavelengths, thereby simplifying the manufacturing process while maintaining high spectral selectivity.
Solution Approach 2:
The etch stop layers act as intermediary reference structures between the dielectric layers and the final cavity formation. By providing these intermediate reference markers, the patent enables precise control of cavity thicknesses during etching without requiring complex real-time measurement and adjustment systems, thus reducing manufacturing complexity while achieving the desired spectral selectivity.
3Manufacturing precision
If multiple etch stop layers with constant total thickness are used in cavities of different thicknesses, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies etch stop layers with different local properties (different materials or thicknesses at different positions) within the same cavity structure. Each etch stop layer is strategically positioned and dimensioned to serve as a reference for achieving the specific target thickness of its corresponding cavity, enabling precise thickness control across multiple cavities with different center wavelengths while managing structural complexity through localized optimization.
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 design enables the integration of spectral filtering capabilities on a single semiconductor chip, reducing size and weight while maintaining high transmittance and spectral selectivity, facilitating the development of compact image sensors.
Implementation Method 1
Each of the first to fourth unit filters may have a center wavelength in a first wavelength range, and the fifth to eighth unit filters may have a center wavelength in a second wavelength range, and each of the first to eighth unit filters may include a Fabry-Perot resonator
Implementation Method 2
a first reflective layer and a second reflective layer spaced apart from each other in a vertical direction, and first and second cavities provided between the first reflective layer and the second reflective layer
Data Source
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AI summary
Provided are a spectral filter, a method of manufacturing the same, and an image sensor and an electronic device each including the spectral filter. The spectral filter includes a plurality of first reflective layers provided spaced apart from each other, and a plurality of cavities provided between the plurality of first reflective layers. The cavities have different thicknesses according to a center wavelength. Each of the cavities includes a plurality of etch stop layers having a constant total thickness according to the center wavelength, and at least one dielectric layer having a total thickness which changes according to the center wavelength, wherein the etch stop layers include materials having etch selectivities different than that of the dielectric layer.