Imaging Sensor Diffraction Gratings With Higher Rectangularity
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Solution Overview
Problem
Conventional methods for forming diffraction gratings on solid-state imaging elements result in reduced rectangularity due to heat-induced deformation, leading to compromised optical characteristics and detection accuracy in distance measurement.
Innovation Solution
A method involving a thermosetting resin layer with a sacrificial pattern formed by light exposure and development, followed by dry etching without baking, to create diffraction gratings with increased rectangularity and improved flatness, ensuring precise diffraction and enhanced sensor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form diffraction gratings on solid-state imaging elements, then the manufacturing process is simple, but the rectangularity of diffraction gratings is reduced due to heat-induced deformation
Solution Approach 1:
The patent applies preliminary action by forming the diffraction grating pattern on a sacrificial layer before finalizing the structure. The pattern is created in advance on a temporary substrate that can be removed later, allowing the diffraction gratings to be formed with high rectangularity without direct heat exposure that would cause deformation. This preliminary patterning step enables precise geometric control before the final device assembly.
Solution Approach 2:
The patent uses a sacrificial layer as an intermediary medium to form the diffraction grating pattern. This intermediate layer serves as a temporary template that allows precise pattern formation without directly exposing the final diffraction grating structure to harmful manufacturing conditions such as high heat. The sacrificial layer is removed after pattern transfer, leaving the high-precision diffraction gratings intact.
2Reliability
If heat treatment is applied during diffraction grating formation, then the resin is cured, but the diffraction gratings deform and lose rectangularity
Solution Approach 1:
The diffraction grating pattern is formed in advance on a sacrificial layer before the final curing and assembly steps. This preliminary patterning allows the geometric shape to be established with high precision before any heat treatment occurs, preventing heat-induced deformation of the final grating structure.
Solution Approach 2:
A sacrificial layer acts as an intermediary that protects the diffraction grating pattern from heat-induced deformation. The pattern is transferred to this intermediate layer which can withstand the manufacturing process without deforming, and then the pattern is replicated to the final structure without direct heat exposure to the grating itself.
3Measurement precision
If the diffraction grating pattern is formed directly on the final structure, then the process is efficient, but the detection accuracy is compromised due to shape deformation
Solution Approach 1:
The diffraction grating pattern is formed in advance on a sacrificial layer with high precision, allowing accurate geometric definition before final assembly. This preliminary high-precision patterning ensures that the diffraction gratings maintain their rectangularity for accurate optical performance and distance measurement, while the additional sacrificial layer step is manageable in the manufacturing process.
Solution Approach 2:
The sacrificial layer serves as an intermediary that enables high-precision pattern formation. By using this intermediate substrate, the diffraction grating pattern can be created with superior geometric accuracy that directly translates to improved measurement precision, while the overall process remains efficient through automated pattern transfer and sacrificial layer removal.
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 approach results in diffraction gratings with increased rectangularity and improved optical characteristics, enhancing the accuracy of distance measurement in solid-state imaging elements.
Implementation Method 1
forming a resist layer on the thermosetting resin layer such that the resist layer has a sacrificial pattern corresponding to diffraction gratings by light exposure and development
Implementation Method 2
dry etching without baking the sacrificial pattern such that a shape of the sacrificial pattern is transferred to the thermosetting resin layer
Implementation Method 3
a diffraction grating part formed on the flattening layer and including a thermosetting resin such that the diffraction grating part has diffraction gratings
Data Source
AI summary
A solid-state imaging element including a lens array in which micro lenses are formed in an alignment, a flattening layer formed on the lens array, and a diffraction grating part including a thermosetting resin, has diffraction gratings, and is provided on the flattening layer. A solid-state imaging element including a lens array in which micro lenses are in an alignment, a flattening layer formed on the lens array, and a diffraction grating part including a base that covers the entire upper surface of the flattening layer, and diffraction gratings provided so as to protrude from the base.