Spring-Loaded Fastening System for Graphite Liners
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Solution Overview
Problem
Conventional graphite liners in ion implanter process chambers are difficult to install and remove due to the use of metal fasteners, which require shielding and can cause surface texture interruptions, and are brittle, necessitating careful torque application and extensive cleaning to prevent contamination buildup.
Innovation Solution
A spring-loaded fastening system featuring a frustoconical cleat with a spring element and a shoulder bolt, allowing for tool-free installation and removal of graphite liners without the need for additional shielding or caps, and accommodating thermal expansion and tolerance stack-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical fasteners (bolts) are used to secure graphite liners, then the liners can be firmly attached to process chamber surfaces, but the installation and removal become time-consuming and tedious due to strict torque requirements and brittleness of graphite
Solution Approach 1:
The patent replaces traditional mechanical fastening systems (bolts, nuts, torque tools) with a spring-loaded cleat mechanism. The spring element provides continuous pressure to secure the liner, while the cleat geometry (frustoconical shape with enlarged upper portion) enables tool-free installation by simply placing the liner over the cleat. This substitution eliminates the need for torque tools and complex fastening procedures, dramatically reducing installation and removal time while maintaining secure attachment.
Solution Approach 2:
The spring-loaded mechanism introduces dynamic elements to the fastening system. The spring element can compress and expand to accommodate thermal expansion and tolerance stack-up, maintaining consistent attachment pressure. This dynamic capability allows the system to adapt to changing conditions during operation, ensuring reliable attachment without requiring precise pre-torquing or complex adjustment procedures.
2Strength
If metal fasteners are used to attach graphite liners, then secure mounting is achieved, but surface texture interruptions and contamination risk occur requiring additional shielding and caps
Solution Approach 1:
The patent extracts the fastening function from traditional metal fasteners and relocates it to spring-loaded cleats positioned at the rear of the liner. This extraction removes the source of surface texture interruptions and contamination risks from the process chamber interior. The cleats are mounted on the rear surface, away from the chamber interior, eliminating the need for shielding caps and maintaining smooth surface textures throughout the chamber.
Solution Approach 2:
The spring-loaded cleat acts as an intermediary mechanism that provides secure mounting without direct metal-to-graphite contact in the chamber interior. The cleat mechanism transfers and distributes mounting forces through the liner structure, eliminating the need for exposed metal fasteners that would interrupt surface textures or require additional shielding components.
3Strength
If conventional mechanical fasteners are used, then liners can be secured, but extensive cleaning is required to prevent contamination buildup on process chamber surfaces
Solution Approach 1:
By extracting the fastening mechanism from the process chamber interior and relocating it to the rear surface, the patent eliminates the primary sources of contamination (metal fasteners and shielding caps). This extraction removes the need for extensive cleaning operations, as the fastening components are positioned where they cannot contribute to contamination buildup on chamber surfaces exposed to ion beams and sputtered material.
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
Facilitates convenient and expeditious installation and removal of graphite liners, preventing contamination buildup and surface texture disruptions while ensuring secure mounting and minimizing risk of damage from thermal expansion and tolerance issues.
Implementation Method 1
a spring element disposed on a floor of the interior cavity
Data Source
AI summary
A spring-loaded fastening system for fastening a liner to a structure, including a spring-loaded fastener with a cleat defining an interior cavity, a spring element disposed on a floor of the interior cavity, and a shoulder bolt with head portion disposed on the spring element, with a shoulder portion of the shoulder bolt extending through a mounting aperture in a floor of the interior cavity and a threaded portion of the shoulder bolt fastened to the structure. The system further includes a hanger pocket in a rear surface of the liner including a first portion with an opening large enough to accommodate a diameter of a lower portion of the cleat and not large enough to accommodate a diameter of an upper portion of the cleat, and a second portion adjoining the first portion with an opening large enough to accommodate the diameter of the upper portion of the cleat.