Wafer Focusing and Leveling Measurement Device Drift Compensation
Solution Overview
Problem
Conventional measurement devices for focusing and leveling in photolithography do not account for detector drift, leading to measurement inaccuracies and instability due to positional variations caused by power consumption and environmental factors.
Innovation Solution
A measurement device with a measuring optical path and a first monitoring optical path, where measuring and monitoring light sources create marks on a detector, allowing for the calculation and compensation of detector drift to correct vertical deviations in wafer positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional measurement device uses a detector to measure wafer position, then measurement function is provided, but detector drift causes measurement accuracy to deteriorate
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring detector position using the monitoring optical path and using this information to correct measurement results through software compensation, creating a closed-loop system that maintains measurement accuracy despite detector drift
Solution Approach 2:
The patent introduces a monitoring optical path as an intermediary system that separately measures detector position without interfering with the main measurement function, allowing drift detection and compensation while preserving the primary measurement capability
2Reliability
If a monitoring optical path is added to detect detector drift, then measurement stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the monitoring optical path with the main measuring optical path by having them share common components such as the measuring prism and detector, allowing drift monitoring functionality to be integrated into the existing measurement device structure rather than requiring completely separate systems
Solution Approach 2:
The monitoring optical path is designed to use the same detector as the main measurement path, making the detector multi-functional for both primary measurement and drift monitoring, thereby reducing the need for additional dedicated components
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 improves measurement accuracy and stability by monitoring and correcting detector drift, thereby eliminating errors in wafer measurement results.
Implementation Method 1
a measuring illumination unit configured to emit a measuring light which is projected by the projection lens group onto a wafer and reflected by the wafer onto the measuring detector
Implementation Method 2
a first monitoring illumination unit configured to emit a first monitoring light which enters the measuring prism and is then projected onto the measuring detector
Data Source
AI summary
A measurement device and method for focusing and leveling are disclosed. The device includes a measuring optical path and a first monitoring optical path. Measuring light in the measuring optical path interacts with a wafer and is then incident on a measuring detector to form thereon a measuring mark. First monitoring light in the first monitoring optical path is incident on a measuring detector to form thereon a first monitoring mark. An error in a measurement result of the wafer that arises from a drift of the measuring detector can be eliminated by compensating for a vertical deviation of the wafer obtained by subtracting a drift of the first monitoring mark from a displacement of the measuring mark. In this way, measurement accuracy and stability can be improved by monitoring and correcting the drift of the measuring detector.