Cone-Rectangular Lightpipe for Uniform Specimen Illumination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Incoherent illumination systems for semiconductor inspection face challenges in achieving uniform angular and spatial light distribution, leading to reduced detection resolution and sensitivity due to non-uniform light distribution, which affects the performance of inspection systems.
Innovation Solution
A novel lightpipe configuration with a cone-shaped portion for angular redistribution and a rectangular-shaped portion for spatial redistribution, formed contiguously to minimize light loss and ensure uniformity across the pupil and field stop, converting low NA light to high NA light to meet the requirements of high NA inspection systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a plasma arc lamp with elliptical reflector is used to generate bright light, then illumination intensity is improved, but angular and spatial distribution uniformity deteriorates
Solution Approach 1:
The lightpipe is segmented into two distinct portions: a cone-shaped portion for angular redistribution and a rectangular-shaped portion for spatial redistribution. This segmentation allows each portion to independently optimize its function, with the cone-shaped portion correcting angular non-uniformity and the rectangular-shaped portion correcting spatial non-uniformity, thereby resolving the contradiction between intensity and uniformity
Solution Approach 2:
The lightpipe acts as an intermediary component between the plasma arc lamp and the specimen. It receives non-uniform light from the lamp and transforms it into uniformly distributed light through its two portions, mediating the transition from intense but non-uniform illumination to bright and uniform illumination across the pupil plane and field of view
2Manufacturing precision
If conventional separate light redistribution components are used, then angular and spatial redistribution can be achieved, but light loss increases and system complexity increases
Solution Approach 1:
The cone-shaped portion and rectangular-shaped portion are merged into a single integrated lightpipe structure that is contiguously formed as one piece. This merging eliminates the need for separate components and their associated interfaces, reducing light loss at boundaries while maintaining the dual functionality of angular and spatial redistribution
Solution Approach 2:
The single lightpipe structure performs multiple functions: it guides light from the plasma arc lamp, redistributes angular distribution through its cone-shaped portion, redistributes spatial distribution through its rectangular-shaped portion, and delivers uniformly distributed light to the specimen. This multi-functionality reduces system complexity and minimizes light loss compared to multiple separate components
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 solution achieves significant light redistribution with minimal loss, enhancing the resolution and sensitivity of inspection systems by ensuring uniform light distribution across the entire numerical aperture transmission window, improving detection capabilities.
Implementation Method 1
a lightpipe configured for modifying a spatial distribution of light and an angular distribution of light
Data Source
AI summary
A system for illuminating a specimen are disclosed herein. In general, the system may include an illumination source configured to generate light with an uneven distribution at a pupil plane and field stop of the system, a lightpipe coupled for redistributing the light across the pupil plane and field stop, and at least one optical element configured to direct the redistributed light onto a specimen. The lightpipe may generally include a cone-shaped portion and a rectangular-shaped portion. The cone-shaped portion is configured for modifying an angular distribution of the generated light, so that the redistributed light is uniformly distributed across the pupil plane of the system. The rectangular-shaped portion is formed contiguous with the cone-shaped portion and configured for modifying a spatial distribution of the generated light, so that the redistributed light is uniformly distributed across a field stop of the system. A method for illuminating a specimen and a system for inspecting a specimen are also disclosed herein.