PVD Process Kit Geometry for Dark-Space Particle Reduction
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Solution Overview
Problem
In physical vapor deposition processes, the accumulation of sputtered material in the dark-space region of sputtering chambers leads to undesirable deposits on chamber components, causing plasma shorting, arcing, and contamination, which requires frequent cleaning and replacement of components.
Innovation Solution
A process kit comprising a shield with a cylindrical band and a cover ring is designed to encircle the sputtering target and substrate support, featuring a sloped wall with gas holes and a bulb-shaped protuberance to block line-of-sight deposition, reducing sputtered material accumulation and flaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a process kit with shield and cover ring is used to receive excess sputtered material, then deposition on chamber walls is reduced, but sputtered material accumulates in the dark-space region causing plasma shorting and arcing
Solution Approach 1:
The invention extracts the harmful sputtered material from the dark-space region by providing a shield with a sputtered material reception surface that actively captures and removes material before it can accumulate and cause plasma shorting or arcing
Solution Approach 2:
The shield acts as an intermediary component positioned between the target and chamber walls, intercepting sputtered material on its reception surface and preventing it from reaching critical areas where it would cause plasma instability
2Object-affected harmful factors
If process kit components are used to protect chamber walls, then deposition is reduced, but accumulated deposits require frequent disassembly and cleaning
Solution Approach 1:
The shield is designed as a sacrificial component that can be easily replaced rather than cleaned, accepting wear from sputtered material accumulation and providing a cost-effective solution that eliminates time-consuming cleaning cycles
Solution Approach 2:
The process kit is segmented into replaceable components (shield, cover ring) that can be independently maintained, allowing the shield to be swapped out when depleted without affecting other chamber components
3Quantity of substance
If sputtered material is allowed to accumulate in dark-space region, then shield reception surface is utilized, but deposits flake off due to thermal stresses contaminating the chamber
Solution Approach 1:
The shield reception surface incorporates a porous coating that allows sputtered material to penetrate and embed within the porous structure, creating strong mechanical interlocking that prevents flaking even under thermal stress
Solution Approach 2:
The shield utilizes composite construction with a substrate and porous coating layer, combining the structural integrity of the base material with the particle-retention properties of the porous surface layer
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 process kit effectively reduces the accumulation of sputtered deposits on chamber components, minimizing plasma instability and contamination, thereby extending the time between cleaning cycles and improving deposition uniformity.
Implementation Method 1
at least one gas hole located on the sloped wall to allow process gas to pass therethrough
Implementation Method 2
In PVD chambers, a target is sputtered by energized gas to sputter target material which then deposits on the substrate facing the target
Implementation Method 3
a target is sputtered by energized gas to sputter target material which then deposits on the substrate
Implementation Method 4
the bulb-shaped protuberance of the cover ring blocks a line-of-sight between the at least one gas hole on the shield and an entrance to a chamber body cavity
Data Source
AI summary
A process kit comprises a shield and ring assembly for positioning about a substrate support in a processing chamber to reduce deposition of process deposits on internal chamber components and an overhang edge of the substrate. The shield comprises a cylindrical band having a top wall configured to surround a sputtering target and a sloped portion of a bottom wall having a substantially straight profile with gas conductance holes configured to surround the substrate support. The ring assembly comprises a cover ring having a bulb-shaped protuberance about the periphery of the ring. The bulb-shaped protuberance of the cover ring is able to block a line-of-sight between the gas conductance holes on the shield and an entrance to a chamber body cavity in the processing chamber.