Self-Centering PVD Target Assembly with Alignment Slots
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Solution Overview
Problem
Current physical vapor deposition (PVD) chambers face inaccuracies in aligning the process shield and target, particularly under higher RF frequencies, leading to plasma irregularities and arc events that negatively impact deposition quality.
Innovation Solution
The design incorporates a target assembly with a backing plate and target material bonded together, featuring slots along the periphery to align with the process shield, ensuring a uniform gap and preventing arcing, which improves alignment and deposition symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the process shield and target are mounted separately on the chamber body and lid, then the components can be independently installed and maintained, but the alignment between the process shield and target becomes inaccurate
Solution Approach 1:
The patent combines the process shield and target into a single integrated assembly that is mounted together on the chamber body. The process shield is attached to the target holder, creating a unified structure where the relative position between the process shield and target is fixed, thereby eliminating alignment errors while maintaining ease of installation as a single unit.
Solution Approach 2:
The patent introduces an alignment feature (such as a alignment pin or keyed interface) as an intermediary element between the process shield assembly and the chamber body. This intermediary feature ensures precise alignment during installation by providing a mechanical reference that guides the correct positioning of the integrated assembly.
2Productivity
If higher frequencies of radio frequency energy are applied to the target, then the deposition process can be accelerated, but plasma irregularities and arc events increase due to alignment sensitivity
Solution Approach 1:
By integrating the process shield with the target holder, the patent eliminates misalignment between these components. This ensures uniform spacing between the target and chamber walls, which stabilizes the plasma distribution during high-power RF operation, preventing arc events and enabling sustained high deposition rates.
Solution Approach 2:
The integrated design creates a more uniform electromagnetic field distribution by eliminating gaps and misalignments between the target and process shield. This equipotential configuration reduces field concentration at misaligned edges, preventing localized plasma instabilities and arc formation during high-power operation.
3Ease of manufacture
If separate alignment features are used to align the target and process shield, then the components can be independently manufactured, but the alignment is inadequate for certain applications
Solution Approach 1:
The patent integrates the process shield attachment features directly into the target holder structure. This merging eliminates the need for separate alignment features between independently manufactured components, as the process shield is designed to be attached as part of the target assembly, ensuring precise and consistent alignment.
Data Source
AI summary
In some embodiments, a target assembly, for use in a substrate processing chamber having a process shield, may include a backing plate having a first side and an opposing second side, wherein the second side comprises a first surface having a first diameter bounded by a first edge; a target material having a first side bonded to the first surface of the backing plate; wherein the first edge is an interface between the backing plate and the target material; a plurality of slots disposed along an outer periphery of the backing plate extending from the first side of the backing plate toward the second side of the backing plate, wherein the plurality of slots are configured to align the target assembly with respect to the process shield.