Rectangular Glass Substrate Edge Geometry for Contamination Control
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Solution Overview
Problem
Glass substrates continue to experience surface contamination with submicron-sized particles and contaminants despite cleaning methods, leading to reduced product yield and defects in semiconductor-related applications.
Innovation Solution
A rectangular glass substrate design featuring chamfered surfaces with specific average gradients and roughness values, combined with a method of polishing using a brush and platen with controlled spacing and abrasives, to prevent surface contamination and ensure effective cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods (dip-cleaning or single-substrate cleaning) are used, then cleaning process is simple and efficient, but submicron-sized particles and contaminants remain on the surface
Solution Approach 1:
The patent applies local quality by creating a chamfered surface with specific geometric characteristics (average gradient of 20-40%, curvature radius of 10-100 μm) only at the edge regions where contamination occurs, while maintaining the front surface flat and clean for optical applications. This localized structural modification specifically addresses contamination at the edges without affecting the overall cleaning efficiency or requiring complex cleaning processes.
Solution Approach 2:
The patent employs curvature by forming a rounded chamfered surface with a specific curvature radius (10-100 μm) at the edge lines where the front surface meets the side surfaces. This curved geometry prevents particle accumulation and facilitates contaminant removal during cleaning, while the curvature is precisely controlled to maintain structural integrity and optical performance.
2Strength
If the chamfered surface is made more rounded (larger curvature radius) to prevent cracking, then fracture strength improves, but contamination resistance at the front surface deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying different geometric characteristics to different regions: the chamfered surface has a curvature radius of 10-100 μm for strength, while the front surface maintains flatness and smoothness for contamination resistance. The specific average gradient (20-40%) of the chamfered surface ensures both structural integrity and effective contaminant removal without excessive rounding.
3Reliability
If the edge line portions are chamfered to facilitate contaminant removal, then cleaning effectiveness improves, but the substrate becomes more prone to cracking and chipping
Solution Approach 1:
The patent uses controlled curvature by forming a rounded chamfered surface with a curvature radius of 10-100 μm at the edge lines. This specific curvature range is sufficient to prevent cracking and chipping during handling while maintaining the geometric features needed for effective contaminant removal during cleaning processes.
Solution Approach 2:
The patent applies parameter changes by precisely controlling the average gradient (20-40%) and curvature radius (10-100 μm) of the chamfered surface. These optimized parameters balance the competing requirements: a gradient that is not too steep (to prevent cracking) but still effective for contaminant removal, and a curvature radius that provides structural strength while maintaining cleaning effectiveness.
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 substrate effectively prevents surface contamination of submicron size after cleaning, independent of the cleaning method, thereby maintaining production yield and reducing defects.
Implementation Method 1
polishing the side surfaces and chamfered surfaces with a brush
Implementation Method 2
polishing the side surfaces and chamfered surfaces with a brush and platen with controlled spacing and abrasives
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A rectangular glass substrate has a front surface, a back surface, four side surfaces, and eight chamfered surfaces, and a thickness of at least 6 mm. A first curved surface along the edge line between the front surface and the chamfered surface disposed adjacent thereto has an average gradient of not more than 25 % in a range from the front surface to a position of 50 µm below the front surface when the substrate is rested horizontal with the front surface facing upward. A second curved surface along the edge line between at least one of four side surfaces and the chamfered surface disposed adjacent to the front surface has an average gradient of at least 30 % in a range from the at least one side surface to a position of 50 µm below the at least one side surface when the substrate is rested horizontal with the at least one side surface facing upward.