Mirror-Based Inspection for Lithographic Process Tools
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Solution Overview
Problem
Lithographic apparatuses face challenges in minimizing downtime for maintenance and inspection, as traditional methods are time-consuming and risk contamination, especially when inspecting components like liquid confinement structures, which can lead to increased defectivity and productivity losses.
Innovation Solution
A process tool with a movable stage and an imaging device mounted on a fixed part, using a mirror on the movable stage to image components without opening the apparatus, allowing for contamination detection without exposing the system to the environment, thus reducing downtime and contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional inspection methods are used to inspect components like liquid confinement structures, then the component can be examined, but the apparatus must be opened which causes downtime and contamination risks
Solution Approach 1:
A mirror is introduced as an intermediary element mounted on the movable stage. This mirror reflects light from components (such as the liquid confinement structure) to a fixed imaging device, enabling inspection without opening the apparatus. The mirror acts as a mediator that bridges the gap between the component and the imaging device while maintaining the sealed environment.
Solution Approach 2:
Instead of directly observing the component, an optical copy or image of the component is created by the imaging device via the mirror. This allows the inspection to be performed on the captured image rather than requiring direct visual access to the component, thereby eliminating the need to open the apparatus.
2Ease of operation
If the apparatus is opened for maintenance and inspection, then components can be accessed, but contamination can occur and productivity is reduced
Solution Approach 1:
The mirror serves as an intermediary that enables the imaging device to access components optically without physical access. This maintains the sealed environment while providing inspection capability, thus avoiding contamination and minimizing downtime.
Solution Approach 2:
The mechanical action of opening the apparatus is replaced by an optical system consisting of the mirror and imaging device. Instead of physically accessing components by opening the apparatus, the inspection is performed through optical reflection, substituting mechanical intervention with an optical measurement system.
3Reliability
If a fixed imaging device is used with a movable stage and mirror, then inspection can be performed without opening the apparatus, but the system complexity increases
Solution Approach 1:
The movable stage and mirror assembly serves multiple functions: it positions substrates for processing and simultaneously enables inspection of components when positioned at specific locations. This multi-functionality reduces the need for separate dedicated inspection mechanisms, thereby limiting the increase in system 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
Enables efficient inspection of critical components within the lithographic apparatus without opening it, minimizing downtime and contamination risks, and allowing for quick detection of contaminants, thereby maintaining productivity and reducing defectivity.
Implementation Method 1
a mirror mounted on the movable stage and oriented at a predetermined angle of inclination to the X-Y plane so that by moving the movable stage to a predetermined position a part of the component can be imaged by the imaging device
Data Source
AI summary
A process tool for processing production substrates, the process tool including: a movable stage configured to perform long-stroke movements in an X-Y plane; an imaging device mounted to a fixed part of the tool and having an optical axis substantially parallel to the X-Y plane; and a mirror mounted on the movable stage and oriented at a predetermined angle of inclination to the X-Y plane so that by moving the movable stage to a predetermined position a part of a component to be inspected can be imaged by the imaging device.