Glass Substrate Flatness Control via Two-Step Ion Beam Processing
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Solution Overview
Problem
Conventional methods for processing glass substrates, such as dry etching and magnetic viscous fluid polishing, often result in surface roughness issues and low productivity, making it difficult to achieve the required high flatness and smoothness for reflective mask substrates in EUV lithography.
Innovation Solution
A processing method involving flatness distribution measurement, initial processing with techniques like ion beam etching or gas cluster ion beam etching, followed by finish polishing, where processing conditions are adjusted based on measured flatness and dopant concentration distributions to achieve high flatness and smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching or magnetic viscous fluid polishing is used to process glass substrate surface, then flatness can be improved, but surface roughness increases and productivity decreases
Solution Approach 1:
The processing is divided into two distinct steps: first processing step (dry etching or magnetic viscous fluid polishing) to improve flatness, and second processing step (O2 gas cluster or non-contact polishing) to reduce surface roughness. This segmentation allows each step to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent implements a continuous two-step processing sequence where the first step addresses flatness and the second step immediately follows to address surface roughness. This continuous action ensures that both flatness and surface roughness requirements are met without interrupting the processing flow, thereby improving overall productivity.
2Ease of manufacture
If conventional processing methods are used, then processing can be completed, but defects are generated and productivity is reduced
Solution Approach 1:
The patent implements a continuous two-step processing sequence where the first step addresses flatness and the second step immediately follows to address surface roughness. This continuous action ensures that both flatness and surface roughness requirements are met without interrupting the processing flow, thereby improving overall productivity.
Solution Approach 2:
The patent employs feedback mechanisms to monitor and control the processing parameters in both steps. By measuring the surface condition after the first step and adjusting the second step accordingly, the system optimizes the processing to minimize defects and surface roughness while maintaining high productivity.
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 method enables the production of glass substrates with surface flatness of less than 0.05 μm PV and surface roughness of less than 0.25 nm RMS, significantly improving productivity while reducing defects.
Implementation Method 1
processing by a gas cluster ion beam etching
Implementation Method 2
processing by a plasma etching
Implementation Method 3
processing by a polishing with a magnetic viscous fluid
Implementation Method 4
smoothening process by an O2 gas cluster
Implementation Method 5
non-contact polishing such as EEM
Data Source
AI summary
The present invention is to provide a processing method for manufacturing a highly flat and highly smooth glass substrate with good productivity. A highly flat and highly smooth glass substrate is obtained with good productivity by processing of a glass substrate, which comprises a step of measuring the surface shape of the glass substrate prior to processing, a step of processing the surface of the substrate by changing a processing condition for each site (first processing step), and a step of finish-polishing the surface of the glass substrate that has been subjected to the first processing step (second processing step). At that time, the processing condition for each site within the surface of the substrate in the first processing step is determined from a processing amount that is determined from the concave-convex shape of the surface of the glass substrate prior to processing and the in-plane distribution of a processing amount by the second processing step separately measured by using a similar substrate.