Disposable Magnetic Substrate Holder for Coating Uniformity
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Solution Overview
Problem
Conventional substrate holders in PVD and CVD systems face issues with non-uniform coating thickness, particulate contamination, and high maintenance costs due to mechanical fasteners and abrasive coating buildup, which require frequent cleaning and replacement, leading to misalignment and increased labor costs.
Innovation Solution
A substrate holder with a disposable sheet metal cover that is easily removable and dismantled, featuring a magnetic latch system for secure substrate attachment and protection from stray coating material, allowing for precise alignment and reduced particulate generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional substrate holders are made of hardened stainless steel to ensure durability, then strength and reliability are improved, but manufacturing cost and maintenance complexity increase significantly
Solution Approach 1:
The substrate holder is divided into two functional segments: a durable base made of hardened stainless steel that provides structural strength and magnetic attachment, and a disposable cover made of thin sheet metal that protects the substrate and can be easily replaced. This segmentation allows each part to be optimized for its specific function without requiring the entire assembly to be made of expensive hardened steel.
Solution Approach 2:
The cover portion of the substrate holder is designed as a disposable component made from inexpensive sheet metal. After a certain number of uses or when contamination occurs, only the cover needs to be replaced rather than the entire substrate holder, significantly reducing maintenance costs and downtime while the expensive hardened steel base continues to provide structural integrity.
2Strength
If mechanical fasteners are used to attach substrate holders to spindles, then connection strength is improved, but alignment precision deteriorates due to temperature and pressure changes
Solution Approach 1:
The mechanical fastening system (bolts, screws, clips) is replaced with a magnetic attachment system. The magnetic latch provides sufficient holding strength to secure the substrate holder to the spindle while allowing for thermal expansion and pressure changes without compromising alignment. The magnetic field can accommodate minor dimensional changes while maintaining precise positioning, eliminating the alignment issues caused by rigid mechanical connections.
3Manufacturing precision
If substrate holders are designed with thin surfaces to prevent shadowing of coating flux, then coating uniformity is improved, but structural strength deteriorates
Solution Approach 1:
The substrate holder is segmented into a thin cover and a thicker base structure. The cover, which directly interfaces with the substrate and coating flux, is made from thin sheet metal (0.020-0.030 inches) to prevent shadowing and ensure uniform coating deposition. The base, which provides structural support and magnetic attachment functionality, is made from hardened stainless steel with sufficient thickness to maintain strength. This segmentation allows the thin surface contact area to optimize coating uniformity while the thicker base maintains structural integrity.
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 provides improved uniformity in coating thickness, reduces particulate contamination, and lowers maintenance costs by eliminating the need for frequent cleaning and replacement of substrate holders, while minimizing manual labor and misalignment issues.
Implementation Method 1
a magnetic latch system for secure substrate attachment
Data Source
AI summary
The invention relates to a partially disposable substrate holder used in magnetic latches for securing substrates on a planetary rotating platform suspended above a coating source in a vacuum chamber of a vapor deposition system, e.g. a chemical vapor deposition (CVD) system or a physical vapor deposition (PVD) system. The substrate holder includes a reusable base formed, at least partially, from a ferro-magnetic material, which is attracted to the magnetic latch, and a disposable cover formed from a relatively inexpensive, ferromagnetic, easily formable material, which encourages adherence of coating material and has a low vapor pressure at coating temperatures.