Pin Chuck DLC Coating via Glass Frit Masking
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Solution Overview
Problem
The application of a diamond-like carbon (DLC) coating to pin chucks for semiconductor wafers faces challenges due to thermal expansion mismatch between DLC and the chuck material, leading to mechanical stress and flatness deviations, and existing masking techniques are inefficient and prone to errors.
Innovation Solution
A mixture of binder and glass frit or beads is used to mask non-pin areas on the chuck, followed by DLC coating, and then the masking material is removed, or a nickel-iron alloy is used as a subtractive mask to selectively coat the pin tops, with subsequent removal of the DLC from non-pin areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If DLC coating is applied to the entire chuck surface, then wear resistance and low friction are improved, but thermal stress and flatness deviation increase due to CTE mismatch
Solution Approach 1:
The patent applies DLC coating selectively only to the pin tops rather than the entire chuck surface. This localized coating approach provides wear resistance and low friction where needed (at the contact points with the wafer) while avoiding thermal stress accumulation on the bulk chuck surface, thereby maintaining flatness precision.
2Strength
If DLC coating is applied to the entire chuck surface, then low friction is improved, but contamination control worsens due to metal contact in non-pin areas
Solution Approach 1:
The patent implements local quality by coating only the pin tops with DLC, creating a low-friction surface exactly where the wafer contacts the chuck. The non-pin areas remain uncoated and can be designed with contamination-resistant materials or surface treatments, thus achieving low friction without compromising contamination control.
3Manufacturing precision
If traditional masking techniques are used to block non-pin areas, then selective coating is achieved, but process complexity and error probability increase
Solution Approach 1:
The patent employs preliminary action by pre-forming the chuck with protruding pins that naturally define the coating areas. The pin geometry itself serves as the mask, eliminating the need for separate masking layers or photolithography processes. This simplifies the coating process while maintaining high selectivity.
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 effectively applies DLC only to the pin tops, minimizing thermal stress and ensuring high precision and low contamination, while simplifying the masking process and avoiding issues with previous techniques.
Implementation Method 1
DLC coating is applied to the pin chuck
Implementation Method 2
a nickel-iron alloy is used as a subtractive mask to selectively coat the pin tops
Data Source
AI summary
A method for selectively coating the tops of pins of a pin chuck with a high thermal stability material, such as diamond-like carbon (DLC). Non-pin areas (“valleys”) of the pin chuck support surface are temporarily covered with glass frit or glass beads during the DLC coating operation. After coating, the glass frit/beads masking material may be removed, leaving the DLC material selectively coating the pin tops. The selective DLC coating avoids the cracking or warping problems due to CTE mismatch when DLC is coated over the entire pin chuck support surface, as the pin chuck material typically is very different from DLC.