Wafer Stage Mark Detection Control for Faster Overlay Alignment
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Solution Overview
Problem
Existing lithography processes face challenges in accurately and efficiently measuring the positional relationship of grating marks on a wafer to improve overlay accuracy during the manufacturing of semiconductor devices and liquid crystal display devices.
Innovation Solution
A control method involving the detection and measurement of a first mark on a movable body using a measurement beam, adjusting the relative position between the measurement beam and the movable body in multiple axes, and forming a pattern based on this detection, utilizing a movable body apparatus with a mark detection system and a pattern forming apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measurement beam scans a grating mark on a wafer to detect its position, then the position information can be obtained, but the measurement time increases and productivity decreases
Solution Approach 1:
The patent applies preliminary action by pre-positioning the measurement beam at the expected location of the grating mark based on wafer stage position feedback. Instead of scanning the entire wafer surface, the system predicts where the mark should be and directs the beam there in advance, significantly reducing measurement time while maintaining accuracy
Solution Approach 2:
The system implements feedback by continuously monitoring the wafer stage position and using this information to dynamically adjust the measurement beam position. The control unit receives position information from the wafer stage and commands the beam positioning mechanism to move accordingly, creating a closed-loop system that speeds up measurement
2Reliability
If the measurement beam follows the movement of the wafer, then continuous position tracking is achieved, but the system complexity increases
Solution Approach 1:
The patent introduces an intermediary control unit that mediates between the wafer stage position sensor and the beam positioning mechanism. This control unit processes position information and generates appropriate beam positioning commands, simplifying the overall system architecture while achieving reliable continuous tracking
Solution Approach 2:
The system replaces complex mechanical scanning mechanisms with a combination of precision stage movement and electronically controlled beam positioning. By using the wafer stage's own movement as the primary scanning mechanism and supplementing it with controlled beam positioning, the system reduces mechanical complexity while maintaining tracking capability
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
Enhances the accuracy and efficiency of position measurement of grating marks, improving overlay accuracy in device manufacturing by controlling the position of the movable body within a two-dimensional plane.
Implementation Method 1
detecting a first mark of a plurality of marks provided at an object placed on a movable body while scanning a measurement beam in a direction of a first axis with respect to the first mark
Data Source
AI summary
In a beam irradiation apparatus in which a movable body holds an object, a mark detection system detects a first mark on the movable body while moving the movable body in a first direction and changing an irradiation position of a measurement beam in the first direction, the mark detection system detects a second mark while moving the movable body in the first direction and changing the irradiation position of the measurement beam in the first direction, a controller controls a position of the movable body in a second direction intersecting the first direction during a time period between the detection of the first mark and the detection of the second mark, and the controller controls the movement of the movable body to adjust a positional relation between the object on the movable body and a processing beam, based on results of the detection of the first and second marks.