Segmented Clamp Ring Layout to Prevent PVD Substrate Sticking
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Solution Overview
Problem
In physical vapor deposition (PVD) processes, substrates often stick to clamp rings, leading to damage when separated, resulting in reduced process yield and the need for reprocessing or scrapping, which decreases the number of substrates that can be processed per hour.
Innovation Solution
A clamp ring with an annular circular body and radially extending pads and alignment marks is designed to minimize substrate contact with the clamp ring, reducing the likelihood of sticking by ensuring that only a minimal portion of the clamp ring's circumference comes into contact with the substrate during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrates are held in place by components of a process kit during PVD processing, then substrates can be securely positioned and processed, but substrates may stick to the clamp ring causing damage when separated
Solution Approach 1:
The clamp ring is divided into multiple discrete pads instead of being a continuous circular structure. These pads are spaced around the inner periphery, creating discrete contact zones that minimize the area where substrates can stick while maintaining secure positioning during PVD processing.
Solution Approach 2:
The clamp ring structure transitions from uniform contact around the entire circumference to non-uniform localized contact at specific pad positions. This localizes the interaction between clamp ring and substrate, reducing the harmful sticking effect while maintaining necessary clamping function at critical locations.
2Productivity
If substrates stick to the clamp ring and are separated, then processing can continue, but substrate damage occurs requiring reprocessing or scrapping
Solution Approach 1:
By segmenting the clamp ring into discrete pads, the invention minimizes substrate-clamp ring contact area, preventing sticking in the first place. This eliminates the need for damaging separation operations and maintains both substrate integrity and processing productivity.
Solution Approach 2:
The invention converts the potential harmful effect of clamp ring-substrate contact into a beneficial minimal contact scenario. The discrete pads are positioned and sized to provide necessary clamping while inherently preventing the sticking phenomenon that causes damage and reduces productivity.
3Strength
If a continuous clamp ring structure is used, then substrates are securely held during processing, but the contact area increases the likelihood of sticking
Solution Approach 1:
The continuous clamp ring is segmented into multiple discrete pads distributed around the inner periphery. This segmentation maintains the holding capability by providing multiple localized contact points while dramatically reducing the total contact area, thereby preventing sticking.
Solution Approach 2:
Instead of providing continuous contact around the entire clamp ring circumference, only partial contact at specific pad locations is provided. This partial action is sufficient to secure substrates during processing while avoiding the excessive contact that causes sticking.
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
This design reduces the risk of substrate damage and increases the throughput of the PVD chamber by preventing unnecessary reprocessing and scrapping, allowing for more efficient film deposition.
Implementation Method 1
Physical vapor deposition (PVD) is a commonly used process in the fabrication of semiconductor industry. The PVD process is a plasma process performed in a vacuum chamber where a negatively biased sputtering target is exposed to plasma of an inert gas
Implementation Method 2
Bombardment of the sputtering target by ions of the inert gas results in ejection of atoms of the sputtering target material
Data Source
AI summary
A clamp ring including an inner periphery of increased diameter at locations where inwardly extending tabs are not located reduces the risk a workpiece that is placed in close proximity to the clamp ring or which contacts the clamp ring during processing will stick to the clamp ring.