High Temperature Electrode Connections for Wafer Pedestals
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Solution Overview
Problem
In semiconductor fabrication, external electrodes on pedestals experience high thermal cycling and mechanical stresses due to handling and maintenance, leading to unreliable electrical connections and potential damage.
Innovation Solution
A high temperature electrode assembly featuring single-piece electrode rods with a floating plate and anti-rotation retainer rings, along with Belleville washers, is designed to provide secure electrical connectivity while allowing for thermal expansion and reducing mechanical stresses through a combination of material selection and structural features like circumferential grooves and index marks for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external electrodes are attached to studs in the pedestal, then electrical connectivity to devices is achieved, but the electrodes experience high thermal cycling and mechanical stresses leading to unreliable connections
Solution Approach 1:
The electrode assembly is divided into separate functional components: electrode rods for electrical connection, a floating plate for mechanical support, and anti-rotation retainer rings for positional stability. This segmentation allows each component to address specific stresses independently, improving overall connection reliability under thermal cycling conditions.
Solution Approach 2:
The floating plate is designed to move dynamically with thermal expansion and contraction of the pedestal, rather than being rigidly fixed. This dynamic adaptation absorbs thermal stresses and prevents damage to the electrode-stud connections during temperature cycling.
2Object-affected harmful factors
If the electrode rod cross-sectional area is reduced to lower thermal loads, then thermal conduction to seals is reduced, but mechanical strength may be compromised
Solution Approach 1:
The electrode rod features a stepped cross-section with different diameters along its length. The upper portion has a smaller diameter to reduce thermal conduction to external components, while the lower portion near the stud connection maintains a larger diameter to ensure mechanical strength and stress resistance at the critical connection point.
3Stability of the object's composition
If the floating plate fits tightly in the pedestal stem, then lateral movement of electrode rods is prevented, but thermal expansion movement is restricted
Solution Approach 1:
The floating plate is designed with intentional clearance relative to the pedestal stem, allowing it to move dynamically in the axial direction to accommodate thermal expansion and contraction of the electrode rods. Anti-rotation posts and retainer rings provide rotational and lateral constraints, maintaining stability while permitting necessary thermal movement.
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 enhances the reliability and durability of electrical connections by mitigating thermal and mechanical stresses, allowing for longer maintenance intervals and improved performance across high-temperature cycles.
Implementation Method 1
a Belleville washer is installed between a shoulder of the stud embedded in the pedestal and the cup of the electrode rod. In one case, the Belleville washer is at least partially flatted to preload the washer.
Implementation Method 2
The anti-rotation retainer ring frictionally engages the electrode rod and the anti-rotation post limits rotation of the electrode rod with respect to the floating plate.
Implementation Method 3
The floating plate fits within the pedestal stem with enough clearance to allow movement along the axes of the electrode rods during thermal expansion/contraction
Data Source
AI summary
Embodiments include a high temperature electrode connection assembly for a wafer-processing pedestal. The high temperature electrode connection assembly includes an electrode rod having a cup that mounts to a stud embedded in the pedestal and a plate adapter portion. The assembly also includes a floating plate having an outer surface and an aperture for receiving the electrode rod. The floating plate contacts an inner surface of the pedestal to resist lateral movement of the electrode rods. The assembly also includes an anti-rotation retainer ring that frictionally engages the electrode rod and an anti-rotation post extending from the outer surface of the floating plate. The anti-rotation post limits rotation of the electrode rod with respect to the floating plate.