Movable Liquid Immersion Stage for Compact Exposure Apparatus
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Solution Overview
Problem
As semiconductor devices become finer and wafers larger, existing exposure apparatuses face challenges in maintaining high resolution and reducing footprint, particularly when transitioning to 450 mm wafers, as they require multiple stages under the projection optical system for liquid immersion, leading to increased footprint size.
Innovation Solution
A movable exposure apparatus with a holding member and position measurement system that allows for the delivery of a liquid immersion space between the optical member and a movable member, eliminating the need for multiple stages under the optical system, thus reducing the apparatus' footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple stages are placed under the projection optical system to maintain liquid immersion space, then liquid immersion exposure is achieved, but the footprint of the apparatus increases considerably
Solution Approach 1:
The patent combines the liquid immersion space with the movable body (wafer stage) by providing a liquid supply device that supplies liquid to the space between the projection optical system and the wafer stage. This merging eliminates the need for separate stationary liquid immersion stages, thereby reducing footprint while maintaining liquid immersion exposure functionality.
Solution Approach 2:
The patent transitions from a static liquid immersion space (requiring multiple fixed stages) to a dynamic liquid immersion space that moves with the wafer stage. The liquid supply device dynamically supplies liquid to the moving space, enabling the liquid immersion environment to follow the movable wafer stage without requiring additional stationary stages underneath the optical system.
2Productivity
If the wafer size increases to 450 mm, then the number of dies per wafer increases, but the footprint of the exposure apparatus increases considerably
Solution Approach 1:
The patent merges the liquid immersion functionality with the movable wafer stage by integrating the liquid supply device with the stage structure. This eliminates the need for large stationary liquid immersion chambers that would be required for 450 mm wafers, thereby enabling high productivity without proportionally increasing footprint.
Solution Approach 2:
The patent changes the parameter of liquid supply from stationary to mobile by providing a liquid supply device that moves with the wafer stage. This parameter change enables the system to accommodate larger wafer sizes (450 mm) without requiring proportionally larger stationary liquid immersion spaces, thus maintaining compact footprint while supporting high productivity.
3Area of stationary object
If a single movable body is used instead of multiple stages, then footprint is reduced, but the ability to constantly maintain liquid immersion space may be compromised
Solution Approach 1:
The patent employs dynamic liquid supply by providing a liquid supply device that is coupled to the movable body (wafer stage) and moves together with it. This dynamic configuration ensures that liquid is continuously supplied to the immersion space regardless of the stage's position, thereby maintaining reliable liquid immersion exposure while using only a single movable body.
Solution Approach 2:
The patent ensures continuous liquid immersion by providing a liquid supply device that operates continuously as the wafer stage moves. The liquid supply follows the stage throughout its travel range, maintaining uninterrupted liquid immersion conditions without requiring multiple stationary stages to cover different positions.
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 exposure of larger wafers with reduced footprint, maintaining high resolution and throughput by minimizing the number of movable bodies required under the optical system, which is essential for 450 mm wafers.
Implementation Method 1
a position measurement system which has an arm member, extending in a first axis direction parallel to the two-dimensional plane, where at least a part of a head is provided that irradiates at least one measurement beam on a measurement plane placed on a surface substantially parallel to the two-dimensional plane of the holding member, measures positional information of the holding member within the two-dimensional plane, based on an output of the head
Implementation Method 2
a movable member which becomes proximal to the holding member within a predetermined distance in the first axis direction parallel to the two-dimensional plane when the holding member holds a liquid with the optical member, and moves from one side of the first-axis direction to the other side along the arm member with the holding member while maintaining the proximal state, and holds the liquid with the optical member after the movement
Data Source
AI summary
An exposure apparatus is equipped with a fine movement stage that can hold a liquid with a projection optical system when the stage is at a position facing an outgoing surface of the projection optical system, and a blade that comes into proximity within a predetermined distance of the fine movement stage when the fine movement stage is holding the liquid with the projection optical system, and moves along with the fine movement stage while maintaining the proximity state, and then holds the liquid with the projection optical system after the movement. Accordingly, a plurality of stages will not have to be placed right under the projection optical system interchangeably, which can suppress an increase in footprint of the exposure apparatus.