Self-Retained Low-Friction Pads for PVD Target Assemblies
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Solution Overview
Problem
Thermal expansion differences between the sputtering target backing plate and the chamber wall in PVD processes cause friction, leading to wear and contamination of the chamber.
Innovation Solution
A target assembly with self-retained low-friction pads is used, featuring recesses on the backing plate and a self-retaining stem that reduces friction between the target and the chamber, eliminating the need for external fasteners and increasing the bearing surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target backing plate rests directly on the ceramic insulating ring, then the structure is simple, but friction causes wear and contamination
Solution Approach 1:
Low-friction pads are introduced as intermediary elements between the target backing plate and the ceramic insulating ring. These pads reduce friction and prevent direct contact between the metal backing plate and ceramic ring, thereby eliminating wear and contamination while maintaining structural integrity.
Solution Approach 2:
The contact interface between the backing plate and insulating ring is segmented into multiple discrete low-friction pads rather than a continuous contact surface. This segmentation allows for localized friction reduction at critical contact points while maintaining overall structural simplicity.
2Reliability
If external fasteners are used to secure pads, then the pads are firmly attached, but the device complexity increases
Solution Approach 1:
The pad assembly is designed as a self-retaining unit where the pad mechanically secures itself to the backing plate through an integrated retention mechanism. The pad includes a body portion that engages with a recess in the backing plate, eliminating the need for separate external fasteners while ensuring firm attachment.
3Reliability
If the bearing surface area is increased, then friction is reduced, but the device complexity increases
Solution Approach 1:
The low-friction pads extend in the axial direction (perpendicular to the backing plate surface) to increase the bearing surface area without complicating the radial or lateral dimensions. This dimensional approach allows for increased contact area with the insulating ring while maintaining a compact overall structure.
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 effectively reduces wear and contamination by minimizing friction, maintaining a clean chamber environment and improving processing results.
Implementation Method 1
self-retained low-friction pads... reduce the friction at an interface between the target and the PVD chamber
Implementation Method 2
The thermal expansion of the target backing plate and the chamber wall may be different, and have been observed by the inventors to cause the target backing plate and the insulating ring to move relative to each other
Data Source
AI summary
Embodiments of target assemblies for use in substrate processing chambers are provided herein. In some embodiments, a target assembly includes a plate comprising a first side including a central portion and a support portion, a target disposed on the central portion, a plurality of recesses formed in the support portion; and a plurality of self-retained low-friction pads partially disposed in the plurality of recesses, wherein each of the plurality of low-friction pads includes a solid body portion, and a self-retaining stem that extends outward from a bottom of the solid body portion, wherein the self-retaining stem includes a first stem portion disposed in the first through-hole portion, and a second stem portion disposed within the second through-hole portion.