Reflecting Mask Segmented Conductive Patterns for Flatness Control
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Solution Overview
Problem
In photolithography processes using extreme ultraviolet light, existing reflecting masks often result in focus errors and pattern shifts due to inadequate fixation, leading to suboptimal exposure results in semiconductor manufacturing.
Innovation Solution
A reflecting mask with conductive layer patterns spaced apart on its rear face, fixed to an electrostatic chuck using an apparatus with protrusions and adjustable electrostatic forces, ensuring horizontal alignment and flatness through controlled voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflecting mask is fixed to an electrostatic chuck using conventional methods, then the mask can be held in place during exposure, but the mask becomes non-flat causing focus errors and pattern shifts
Solution Approach 1:
The conductive layer is divided into multiple spaced-apart conductive layer patterns on the rear face of the substrate. These segmented patterns correspond to multiple protrusions on the electrostatic chuck, allowing distributed electrostatic fixation points that maintain mask flatness while providing stable fixation during exposure
Solution Approach 2:
The electrostatic fixation system applies different electrostatic forces to different regions of the mask through the conductive layer patterns. By controlling the voltage on each protrusion independently, the system can locally adjust the fixation strength to maintain overall mask flatness while ensuring adequate fixation at critical regions
2Force
If the reflecting mask is made highly conductive for better electrostatic fixation, then fixation strength improves, but charge distribution becomes non-uniform causing distortion
Solution Approach 1:
The conductive layer is segmented into multiple isolated conductive layer patterns spaced apart from each other. This segmentation prevents charge accumulation and non-uniform distribution that would occur in a continuous conductive layer, while still providing sufficient electrostatic fixation force through the distributed patterns
Solution Approach 2:
Each conductive layer pattern has localized conductivity properties optimized for its specific position. The spacing and dimensions of individual patterns can be adjusted to achieve uniform charge distribution across the entire mask surface while maintaining adequate electrostatic fixation force at each location
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
Prevents pattern shifts and focus errors during exposure processes by maintaining the reflecting mask in a flat, horizontal position, enhancing the precision of semiconductor device manufacturing.
Implementation Method 1
The conductive layer pattern may fix the substrate to an electrostatic chuck providing an electrostatic force
Implementation Method 2
The absorbing layer absorbs the extreme ultraviolet light
Implementation Method 3
The reflecting layer is formed on a front face of the substrate to reflect an extreme ultraviolet light
Data Source
AI summary
In a reflecting mask, an apparatus for fixing the reflecting mask and a method of fixing the reflecting mask, voltages are applied to elements of a conductive pattern spaced apart from each other on a rear face of the reflecting mask to fix the reflecting mask by using electrostatic forces. A flatness of the fixed reflecting mask is measured, and the electrostatic forces provided to portions of the reflecting mask are selectively adjusted in accordance with a measured result obtained from the measuring part, such that the reflecting mask is horizontally fixed and is substantially flat.