Cylindrical Reticle Unidirectional Scanning Exposure
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Solution Overview
Problem
Existing exposure apparatuses in semiconductor manufacturing have low efficiency and yield due to the need for accelerating and decelerating processes during exposure, which waste time and reduce accuracy.
Innovation Solution
The exposure apparatus employs a cylindrical reticle system with a unidirectional scanning method, where the cylindrical reticle rotates around its center axis while wafer stages move in a constant direction, eliminating the need for acceleration and deceleration processes by exposing columns of regions continuously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional bidirectional scanning method is used for exposure, then complete coverage of exposure regions is achieved, but exposure time increases and efficiency decreases due to repeated acceleration and deceleration
Solution Approach 1:
The patent inverts the traditional bidirectional scanning approach by implementing unidirectional scanning. Instead of moving the wafer stage back and forth between exposure regions, the system scans continuously in one direction while the cylindrical reticle rotates to present different patterns, eliminating the need for acceleration and deceleration cycles at each exposure region boundary.
Solution Approach 2:
The patent achieves continuous useful action by maintaining constant unidirectional motion of the wafer stage throughout the exposure process. The cylindrical reticle rotates continuously to sequentially present different exposure patterns, allowing the exposure process to proceed without interruption or reversal of motion, thereby maximizing productivity and minimizing time loss.
2Manufacturing precision
If bidirectional scanning is used to expose multiple columns of regions, then all regions are covered, but scanning accuracy decreases and exposure precision is reduced
Solution Approach 1:
The patent inverts the scanning paradigm from bidirectional wafer stage movement to unidirectional wafer stage movement combined with cylindrical reticle rotation. This inversion eliminates the precision loss associated with repeated direction changes, as the wafer stage maintains constant motion direction while the rotating reticle delivers different exposure patterns.
Solution Approach 2:
The patent introduces dynamic rotation of the cylindrical reticle to compensate for the static unidirectional motion of the wafer stage. By dynamically adjusting the reticle's rotational position, the system can present different exposure patterns (first column, second column, etc.) without requiring the wafer stage to change direction, thereby maintaining scanning accuracy and exposure precision throughout the process.
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
This approach significantly reduces exposure time and increases efficiency by maintaining constant speed and direction, enhancing the yield per unit time without changing scanning or rotation directions.
Implementation Method 1
an optical projection unit between the cylindrical reticle and the base for projecting light onto the wafers to perform an exposure
Data Source
AI summary
An exposure apparatus is provided for performing a unidirectional scan-exposure. The exposure apparatus includes a base and a plurality of wafer stages on the base for loading/unloading wafers and successively moving from a first position to a second position of the base cyclically. The exposure apparatus also includes alignment detection units above the first position of the base for detecting alignment marks on the wafer and aligning the wafers and a cylindrical reticle system above the second position of the base. Further, the exposure apparatus includes an optical projection unit between the cylindrical reticle system and the base for projecting light onto the wafers for an exposure. Further, the exposure apparatus also includes an illuminator box and a main control unit.