Photomask Layout Ring Pattern for Dome-Shaped Micro-Lens
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Solution Overview
Problem
The existing micro-lens formation process in CMOS image sensors is sensitive to heating conditions, leading to inconsistent micro-lens profiles due to the reliance on square patterns in photomasks.
Innovation Solution
A photomask layout is created by adding a substantially ring-shaped pattern and assist patterns, such as arc-shaped patterns, during the optical proximity correction step, which helps in defining dome-shaped micro-lenses less sensitive to heating conditions by compensating for image errors and constructive interference effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If square patterns are used in photomasks for micro-lens formation, then the manufacturing process is simple, but the micro-lens profiles become sensitive to heating conditions and inconsistent
Solution Approach 1:
The patent applies optical proximity correction (OPC) during the photomask design stage to pre-compensate for heating-induced profile changes. By adding assist patterns and adjusting pattern geometries before fabrication, the method anticipates and counteracts the distorting effects of subsequent heating steps, ensuring consistent dome-shaped micro-lens profiles without requiring complex post-processing adjustments.
Solution Approach 2:
The patent modifies the photomask pattern parameters by transitioning from simple square patterns to complex patterns with assist features (such as cross-shaped or star-shaped assist patterns). These parameter changes in pattern geometry and complexity enable better control over the heating process outcomes, transforming the micro-lens formation from a heating-sensitive process to a more controllable one with consistent profiles.
2Device complexity
If simple square patterns are used in photomasks, then the pattern formation is straightforward, but the micro-lens shapes become highly sensitive to heating conditions
Solution Approach 1:
The patent applies optical proximity correction (OPC) during the photomask design stage to pre-compensate for heating-induced profile changes. By adding assist patterns and adjusting pattern geometries before fabrication, the method anticipates and counteracts the distorting effects of subsequent heating steps, ensuring consistent dome-shaped micro-lens profiles without requiring complex post-processing adjustments.
Solution Approach 2:
The patent modifies the photomask pattern parameters by transitioning from simple square patterns to complex patterns with assist features (such as cross-shaped or star-shaped assist patterns). These parameter changes in pattern geometry and complexity enable better control over the heating process outcomes, transforming the micro-lens formation from a heating-sensitive process to a more controllable one with consistent profiles.
3Manufacturing precision
If ring-shaped patterns are added to compensate for heating effects, then micro-lens profile consistency improves, but the photomask layout complexity increases
Solution Approach 1:
The patent applies optical proximity correction (OPC) during the photomask design stage to pre-compensate for heating-induced profile changes. By adding assist patterns and adjusting pattern geometries before fabrication, the method anticipates and counteracts the distorting effects of subsequent heating steps, ensuring consistent dome-shaped micro-lens profiles without requiring complex post-processing adjustments.
Solution Approach 2:
The patent modifies the photomask pattern parameters by transitioning from simple square patterns to complex patterns with assist features (such as cross-shaped or star-shaped assist patterns). These parameter changes in pattern geometry and complexity enable better control over the heating process outcomes, transforming the micro-lens formation from a heating-sensitive process to a more controllable one with consistent profiles.
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 method results in micro-lens patterns with improved profiles, reducing sensitivity to heating conditions and enhancing the overall performance of CMOS image sensors.
Implementation Method 1
The correction step includes performing an optical proximity correction (OPC). The OPC is a model-based OPC or rule-based OPC. The OPC is executed manually.
Data Source
AI summary
A method of making a photomask layout is provided. A graphic data of a photomask is provided. The graphic data includes at least one rectangular pattern. A correction step is performed to the graphic data by using a computer. The correction step includes adding a substantially ring-shaped pattern inside the rectangular pattern. A method of forming a photomask by using the photomask layout obtained by the said method is also provided. In an embodiment, the photomask is suitable for defining micro-lenses of a solid-state image sensor.