Substrate Back Surface Cleaning via Variable Pressure Polishing
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Solution Overview
Problem
Existing substrate cleaning technologies, such as those described in JP 2009-123800 A, face difficulties in removing contaminants firmly adhering to the back surface of substrates, leading to non-uniform surfaces and degraded pattern formation accuracy during lithography processes.
Innovation Solution
A substrate cleaning device with a rotation holder and a polisher that moves between the center and outer periphery of the substrate, allowing for controlled removal of contaminants by adjusting the polishing capacity based on the radial position, using a polisher with adjustable pushing force, speed, or rotation speed, and optionally assisted by a cleaning brush.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cleaning brush and cleaning liquid are used to remove contaminants from the substrate back surface, then particles and loose contaminants are removed, but firmly adhering contaminants and suction marks cannot be removed
Solution Approach 1:
The patent changes the physical state and parameters of the cleaning tool by introducing a polisher that applies controlled mechanical pressure and friction to the substrate back surface. The polisher uses polishing pads with specific hardness and surface properties, applying variable pressure (5-50 g/cm²) to remove firmly adhering contaminants that cannot be removed by conventional cleaning brushes and liquids alone.
2Reliability
If strong polishing is applied to remove firmly adhering contaminants, then removal effectiveness improves, but the substrate surface becomes non-uniform
Solution Approach 1:
The patent applies local quality by using a polisher with variable pressure distribution across the substrate surface. The polishing pressure is controlled to be higher in regions with firmly adhering contaminants and lower in clean regions, achieving localized removal without creating non-uniform surfaces. The polishing head can be pressed with different forces at different radial positions to match the local contamination level.
Solution Approach 2:
The patent introduces dynamics by making the polishing pressure adjustable and variable during the cleaning process. The pressing force applied by the polisher can be dynamically changed based on the contamination level at different positions, allowing the system to adapt to varying contamination patterns across the substrate back surface while maintaining surface uniformity.
3Device complexity
If conventional cleaning methods are used, then the cleaning process is simple, but suction marks and contact marks remain on the substrate back surface
Solution Approach 1:
The patent segments the cleaning process into two distinct stages: first, a cleaning brush removes loose particles and surface contaminants; second, a polisher removes firmly adhering contaminants and suction marks. This segmentation allows each component to perform its specialized function effectively, with the polisher specifically targeting the stubborn contaminants that the brush cannot remove.
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 ensures a clean and uniform substrate surface, preventing non-uniform polishing and reducing the occurrence of processing defects caused by contaminants, thereby enhancing the accuracy of pattern formation.
Implementation Method 1
a polisher configured to be capable of coming into contact with the one surface of the substrate... capacity for removing contaminants by the polisher is changed
Implementation Method 2
a rotation holder that holds and rotates the substrate in a horizontal attitude
Data Source
AI summary
In a substrate cleaning device, with a polishing head in contact with one surface of a substrate rotated by a spin chuck, the polishing head is moved at least between a center and an outer periphery of the substrate. Thus, the one surface of the substrate is polished by the polishing head, and contaminants present on the one surface of the substrate are removed. At this time, capacity for removing contaminants by the polishing head is changed according to a position in a radial direction of the substrate. The capacity for removing contaminants refers to capacity for scraping contaminants adhering to the one surface of the substrate, and suction marks, contact marks and the like remaining on the one surface of the substrate by polishing. It is possible to change the capacity for removing contaminants by adjusting a pushing force exerted on the one surface of the substrate from the polishing head, for example.