Wafer Chuck with Linear Actuators for Mask Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for aligning wafers and masks in photolithography processes, such as those using wedge error compensation heads, are not sufficiently precise for large substrates and sub-micron structures, leading to defects and production losses due to non-parallel alignment and mechanical contact requirements.
Innovation Solution
A chuck system with linear actuators and distance measurement sensors that allows for precise adjustment of the gap and tilt between a wafer and a mask without mechanical contact, using a top and bottom plate arrangement with spring bearings and sensors to measure and compensate for tilt and thickness variations, enabling accurate parallel alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a passive mechanical WEC head with springs and brakes is used to align wafer and mask, then the alignment process is simple and mechanical, but the alignment precision is insufficient for large substrates and sub-micron structures
Solution Approach 1:
The patent replaces the passive mechanical WEC head system with an active system using piezoelectric actuators and capacitive sensors. The piezoelectric actuators provide precise position control through electrical actuation rather than mechanical springs and brakes, while capacitive sensors enable non-contact measurement of wafer and mask positions, achieving sub-micron alignment precision without mechanical contact
Solution Approach 2:
The patent transforms the static passive mechanical system into a dynamic active system where piezoelectric actuators can continuously adjust the positions of the wafer and mask in real-time. The system allows for active compensation of alignment errors through electrical control, enabling adaptive alignment precision that responds to measured position deviations
2Manufacturing precision
If piezoelectric actuators with mechanical sensors are used for active WEC, then alignment precision improves, but mechanical contact is required causing abrasion and suitability issues for automatic machines
Solution Approach 1:
The patent replaces mechanical contact-based sensors with capacitive sensors that measure positions without physical contact. This eliminates mechanical abrasion between sensing components and the wafer/mask surfaces, improving reliability for automatic high-volume production while maintaining sub-micron measurement precision through electrical field-based detection
Solution Approach 2:
The patent introduces capacitive sensors as an intermediary measurement method that uses electrical fields rather than mechanical contact. The capacitive sensing system measures wafer and mask positions through non-contact electrical field interaction, serving as a mediator that provides precise measurement data without the harmful mechanical contact that causes wear
3Ease of operation
If relative measurement during WEC process is used, then alignment can be performed, but each separate wafer requires mechanical contact reducing automation capability
Solution Approach 1:
The patent replaces mechanical contact-based measurement with capacitive sensing that enables non-contact, automated measurement of wafer and mask positions. The system can automatically measure and compensate for alignment errors for each wafer without manual intervention or mechanical contact, fully supporting high-volume automated production while maintaining precise alignment operation
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
The solution provides high accuracy in aligning wafers and masks, reducing production losses and enabling precise transfer of structures, even for large substrates, by allowing for non-contact alignment and continuous adjustment during processing.
Implementation Method 1
Between the top plate and the bottom plate of the chuck, linear actuators, e.g. three actuators, are arranged
Implementation Method 2
The top plate is movably supported on the bottom plate by means of spring bearings
Data Source
AI summary
A chuck for aligning a first planar substrate in parallel to a second planar substrate includes a top plate having a top surface for arrangement of the first planar substrate. A bottom plate is at least one distance measuring sensor configured to measure a distance between the top surface of the top plate and a surface of the second planar substrate, and at least three linear actuators in contact with the top plate and the bottom plate. The method for setting a gap between the first and second planar substrate includes measuring the thickness of the first planar substrate and measuring between a surface of the second planar substrate and the top surface of the top plate. The tilt adjusts between a top surface of the first planar substrate or the chuck and the surface of the second planar substrate by using at least three linear actuators of the chuck.