Wafer Chuck Surface Cleaning With Low-Pressure Abrasive Contact
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Solution Overview
Problem
Semiconductor wafer handling tools, particularly wafer chucks, are difficult to clean in-situ due to their dry operation and low bearing area, leading to contamination issues and wear, which affects device yield and tool availability.
Innovation Solution
A method using a treatment tool with a contacting surface featuring turn-up edges to form a toroidal shape, allowing for gentle decontamination of wafer chuck surfaces without altering the surface elevation or roughness, by maintaining contact pressure below the threshold that would abrade the chuck material, and using a fixture with minimal constraint to conform to the chuck's geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a treatment tool is used to engineer the elevation or profile of the chuck surface at higher application pressures, then surface roughness and elevation can be modified, but the chuck surface may be abraded and contaminants may be generated
Solution Approach 1:
The patent applies parameter changes by controlling the application pressure of the treatment tool to remain below the threshold that would cause significant material removal or abrasion of the chuck surface. This allows the tool to effectively remove contaminants and debris through mechanical action while maintaining the original surface elevation and roughness characteristics, thus resolving the contradiction between surface engineering capability and chuck surface protection
2Object-generated harmful factors
If mechanical or chemical cleaning processes are used on wafer chucks, then contaminants can be removed, but the chucks operate in dry conditions and are not suited for aqueous or dry chemical processes
Solution Approach 1:
The patent replaces chemical cleaning processes (aqueous or dry chemical) with a mechanical cleaning approach using a treatment tool that physically contacts and removes contaminants through controlled mechanical action. This substitution is necessary because wafer chucks operate in dry conditions and are not compatible with chemical cleaning processes, yet still require effective contaminant removal capability
3Object-generated harmful factors
If pins are used on wafer chucks to provide minimum contact, then contamination is reduced and flatness is maintained, but the low bearing area makes cleaning and decontamination extremely difficult
Solution Approach 1:
The patent applies segmentation by using a treatment tool with a contacting surface that can be divided into functional zones: a central region for removing contaminants and debris, and a peripheral region with turn-up edges that prevents material removal. This segmented approach allows the tool to effectively clean the low bearing area surfaces created by pins while controlling the depth of material removal, thus resolving the contradiction between contamination control and cleaning accessibility
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
Effectively removes contaminants and debris from wafer chuck surfaces without modifying the surface profile or increasing wear, ensuring high tool availability and minimizing cross-contamination.
Implementation Method 1
At higher application pressures, the treatment tool will abrade the chuck, which here is to be avoided, or at least minimized. Thus, the instant inventors have discovered that the same treatment tool that is used to engineer the elevation or profile of the surface, and its roughness, at lower application pressures can be used to remove grinding debris and other contaminants from the surface.
Data Source
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Figure 3A~3B
AI summary
A method for decontaminating support surfaces of a wafer chuck entails lightly passing a treatment tool having a nominally flat contacting surface over the regions of the chuck where contaminants are to be removed. The treatment tool and the chuck surface may have about the same hardness. The treatment tool may be constrained so that it may conform to the surface being processed. When the treatment tool is contacted to a flat surface, the area of contact may be in the form of a circle, ring or annulus. At application pressures, the treatment tool will abrade the chuck, which here is to be avoided, or at least minimized. Thus, the instant inventors have discovered that the same treatment tool that is used to engineer the elevation profile of the surface, and its roughness, at lower application pressures can be used to remove grinding debris and other contaminants from the surface.