Projection Aligner Segmented Light Blocking Mechanism
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Solution Overview
Problem
Existing projection aligners face inefficiencies in loading and unloading substrates due to large light blocking bodies that require extensive movement, leading to increased processing time and potential dust accumulation, while smaller light blocking units complicate positioning and processing.
Innovation Solution
A projection aligner with a light blocking system comprising two semicircular light blocking members that form an annular shape to cover the substrate edges, featuring removable blades and bases connected to moving and lifting mechanisms for precise positioning and easy setup, allowing for parallel movement to accommodate varying substrate sizes and shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ring-shaped light blocking body is used to cover whole edges of the substrate, then light blocking effectiveness is improved, but the moving distance of the substrate table increases and loading/unloading time increases
Solution Approach 1:
The light blocking body is divided into multiple segments (first light blocking member with first semicircular opening and second light blocking member with second semicircular opening) that can move independently. This segmentation allows the members to approach each other to form a complete ring shape when needed, and separate when substrate loading/unloading is required, thus maintaining light blocking effectiveness while reducing interference with substrate handling operations.
Solution Approach 2:
The light blocking members are made dynamically adjustable through the moving mechanism that controls their approach and separation. The members can transition between a separated state (during substrate loading/unloading) and an assembled ring shape state (during exposure), allowing the system to adapt its configuration based on operational requirements and resolve the contradiction between light blocking effectiveness and loading/unloading efficiency.
2Reliability
If a ring-shaped light blocking body is used to cover whole edges of the substrate, then light blocking effectiveness is improved, but the light blocking body is moved frequently which causes dust accumulation
Solution Approach 1:
By segmenting the light blocking body into movable members, the system can maintain the complete ring shape configuration during exposure without requiring frequent assembly and disassembly. The segmented design allows the members to stay in position during substrate processing, reducing the frequency of movements that cause dust accumulation while maintaining effective light blocking.
Solution Approach 2:
The light blocking members are positioned in advance to form the complete ring shape before substrate exposure begins. This preliminary positioning allows the system to maintain the light blocking configuration throughout the exposure process without frequent adjustments, thereby reducing dust accumulation from repeated movements while ensuring effective light blocking.
3Ease of operation
If a small light blocking unit is used near the edges of the wafer, then handling is easier, but the control unit needs to calculate and control the light blocking position which complicates processing
Solution Approach 1:
The first and second light blocking members are combined to form a complete ring shape that symmetrically covers the substrate edges. This merging approach simplifies the control mechanism because the members can be positioned using fixed reference points on the substrate table, eliminating the need for complex calculations to determine light blocking positions. The symmetric ring configuration ensures uniform light blocking without requiring sophisticated control algorithms.
Data Source
AI summary
A projection aligner comprises a projection optical system for radiating a luminous flux including ultraviolet rays onto a photomask, and projecting said luminous flux which has passed through the photomask onto a substrate to which photoresist is applied; a substrate table for mounting the substrate, and a light blocking means for covering the peripheral portion of the substrate to block luminous flux. The light blocking means (80) includes a first light blocking member (84) and a second light blocking member (86) each having a substantially semicircular opening, and moving means (82, 83) for moving the first light blocking means and the second light blocking means approaching each other and away from each other. As the first light blocking member and the second light blocking member are moved to approach each other, the first light blocking member and the second light blocking member form an annular shape and cover the peripheral portion of the substrate (CB).