Image Sensor Microlens Layout for Overlay Analysis Isolation
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Solution Overview
Problem
Existing image sensing devices face challenges in performing overlay analysis effectively, particularly due to limitations in their structural design and isolation methods.
Innovation Solution
The implementation of a deep trench isolation (DTI) structure in an image sensing device, which includes a pixel region with photoelectric conversion elements and a dummy region with isolated microlenses, allows for efficient light convergence and alignment patterns on the semiconductor substrate, enabling easy overlay analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a deep trench isolation (DTI) structure is implemented to improve overlay analysis capability, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The device is divided into a pixel region and a dummy region, with the dummy region containing isolated microlenses and alignment patterns. This segmentation allows overlay analysis to be performed separately in the dummy region without interfering with the photoelectric conversion elements in the pixel region, thereby improving measurement precision while managing device complexity through functional separation.
Solution Approach 2:
The deep trench isolation structure acts as an intermediary element between the pixel region and the dummy region. It provides physical and optical isolation, enabling the dummy microlenses and alignment patterns to function independently for overlay analysis without affecting the photoelectric conversion elements, thus resolving the contradiction between measurement precision and device complexity.
2Ease of operation
If microlenses are disposed in the dummy region for overlay analysis, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The device is divided into a pixel region and a dummy region, with the dummy region containing isolated microlenses and alignment patterns. This segmentation allows overlay analysis to be performed separately in the dummy region without interfering with the photoelectric conversion elements in the pixel region, thereby improving measurement precision while managing device complexity through functional separation.
Solution Approach 2:
The dummy region with isolated microlenses serves multiple functions: it provides a dedicated area for overlay analysis, contains alignment patterns for reference, and maintains structural integrity of the lens capping layer. This multi-functionality improves ease of operation for overlay analysis while avoiding the need for separate dedicated structures.
3Reliability
If the lens capping layer structure is maintained to prevent flare phenomena, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The deep trench isolation structure is implemented beforehand to provide optical isolation and prevent flare phenomena before they can occur during device operation. By preemptively addressing the potential for light interference between regions, the design maintains reliability while establishing clear manufacturing boundaries that actually simplify precision requirements compared to attempting post-manufacturing corrections.
Solution Approach 2:
The deep trench isolation structure acts as an intermediary element between the pixel region and the dummy region. It provides physical and optical isolation, enabling the dummy microlenses and alignment patterns to function independently for overlay analysis without affecting the photoelectric conversion elements, thus resolving the contradiction between measurement precision and device complexity.
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 device's ability to perform overlay analysis, improving light convergence and preventing issues like flare phenomena, while maintaining the structural integrity of the lens capping layer.
Implementation Method 1
photoelectric conversion elements for converting incident light into an electrical signal
Data Source
AI summary
An image sensing device includes a pixel region provided in a first portion of a semiconductor substrate such that photoelectric conversion elements for converting incident light into an electrical signal are disposed in the first portion of the semiconductor substrate, a dummy region located outside the pixel region to surround the pixel region and provided in a second portion of the semiconductor substrate without including a photoelectric conversion element, first microlenses disposed over the first portion of the semiconductor substrate and in the pixel region, the first microlenses configured to converge the incident light onto corresponding photoelectric conversion elements, second microlenses disposed over the second portion of the semiconductor substrate and in the dummy region, the second microlenses isolated from the first microlenses, and at least one alignment pattern disposed in the second portion of semiconductor substrate so as to be aligned with the second microlenses.