Plasma Dark Space Shield Alignment in PVD
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Solution Overview
Problem
In existing physical vapor deposition (PVD) chambers, the dark space shield and target are often inaccurately aligned due to separate mounting, leading to plasma irregularities and arc events, particularly at higher RF frequencies, which negatively impact deposition quality.
Innovation Solution
The apparatus integrates an annular dark space shield with a support member and seal ring, coupled to the chamber lid, ensuring proper alignment and compression to maintain a seal between the shield, target, and chamber, thereby minimizing misalignment and plasma irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the dark space shield is mounted separately from the target on the chamber body, then the assembly is easier to manufacture and maintain, but the alignment between the dark space shield and target becomes inaccurate
Solution Approach 1:
The dark space shield is integrated with the target assembly as a single unit, eliminating separate mounting operations. The shield is positioned relative to the target through fixed structural relationships within the assembly, ensuring consistent alignment while maintaining ease of assembly by treating them as one component set.
Solution Approach 2:
A support member with a biasing feature acts as an intermediary between the dark space shield and the target assembly. This biasing feature maintains a predetermined gap and concentricity by applying controlled force, serving as a mechanical mediator that ensures precise alignment without requiring complex external mounting structures.
2Productivity
If the frequency of radio frequency energy applied to the target increases, then the deposition process becomes more efficient, but plasma irregularities and arc events increase
Solution Approach 1:
The biasing feature on the support member serves as a mechanical intermediary that maintains optimal spacing between the dark space shield and target. This consistent spacing acts as a stabilizing intermediary structure that prevents plasma irregularities and arc events, allowing high RF frequencies to be used safely for improved deposition efficiency.
Solution Approach 2:
The invention controls the physical parameter of the gap distance between the dark space shield and target through the biasing feature. By maintaining this gap within a predetermined range, the system optimizes plasma behavior at high RF frequencies, enabling both high productivity and reliability through parameter control.
3Reliability
If the dark space shield is positioned too close to the target, then the seal is improved, but plasma irregularities increase due to loss of concentricity
Solution Approach 1:
The biasing feature acts as a precise mechanical intermediary that maintains the optimal gap distance. It applies controlled force to position the dark space shield at the correct distance from the target, simultaneously achieving both good seal quality and plasma concentricity through balanced mechanical constraint.
Solution Approach 2:
The invention controls the critical parameter of gap distance through the biasing feature's mechanical action. By maintaining this parameter within an optimal range, the system achieves both adequate sealing and plasma stability, resolving the contradiction between seal quality and concentricity.
Data Source
AI summary
In some embodiments, substrate processing apparatus may include a chamber body; a lid disposed atop the chamber body; a target assembly coupled to the lid, the target assembly including a target of material to be deposited on a substrate; an annular dark space shield having an inner wall disposed about an outer edge of the target; a seal ring disposed adjacent to an outer edge of the dark space shield; and a support member coupled to the lid proximate an outer end of the support member and extending radially inward such that the support member supports the seal ring and the annular dark space shield, wherein the support member provides sufficient compression when coupled to the lid such that a seal is formed between the support member and the seal ring and the seal ring and the target assembly.