Air-Cooled Faraday Shield for Stable Plasma Etch Deposition
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Solution Overview
Problem
In plasma etching processes, Faraday shields in semiconductor manufacturing experience temperature fluctuations due to RF-induced heating, leading to deposition flaking or peeling, which interferes with the etching process and requires frequent chamber cleaning.
Innovation Solution
A system utilizing a hub with an internal plenum to interface with the Faraday shield, allowing for controlled airflow to regulate its temperature, using compressed dry air or air amplifiers to maintain a stable temperature and minimize thermal cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Faraday shield is used to block deposition onto the window, then the window is protected from particle flaking, but the Faraday shield itself accumulates deposition that flakes off over time
Solution Approach 1:
The patent introduces a cooled Faraday shield as an intermediary component between the plasma environment and the window. By actively cooling the shield, the deposition material remains stable and does not flake off. The cooling system acts as a mediator that prevents the harmful flaking effect while maintaining the shield's protective function.
Solution Approach 2:
The patent changes the temperature parameter of the Faraday shield by introducing a cooling system. By maintaining the shield at a lower, stable temperature, the deposition material adheres more stably and does not flake off during thermal cycling. This parameter change transforms the shield from a passive component to an actively controlled one.
2Productivity
If the Faraday shield is subjected to temperature cycling during etch processes, then the etching process can be performed, but the deposition on the shield flakes or peels off
Solution Approach 1:
The patent actively controls the temperature parameter of the Faraday shield by introducing a cooling system. This maintains the shield at a stable temperature even during process cycling, preventing thermal expansion and contraction that would cause deposition to flake or peel.
Solution Approach 2:
The cooling system provides beforehand cushioning by pre-cooling the Faraday shield before the etching process begins. This preparatory cooling creates a thermal buffer that absorbs subsequent temperature variations, preventing deposition instability during the actual etching process.
3Power
If excessive temperatures are applied to the Faraday shield, then the shield can withstand high power, but the coating peels off
Solution Approach 1:
The patent changes the temperature parameter of the Faraday shield by introducing active cooling. This allows the shield to handle high RF power while maintaining a lower operating temperature, preventing the coating from peeling off due to excessive heat.
Solution Approach 2:
The cooling system acts as an intermediary between the high-power RF environment and the Faraday shield coating. It provides thermal management that protects the coating from direct exposure to excessive temperatures, maintaining coating adhesion while allowing high power operation.
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 controlled airflow system effectively reduces the Faraday shield's temperature and minimizes thermal cycling, preventing deposition flaking and extending the interval between chamber cleanings by maintaining a stable temperature environment.
Implementation Method 1
A flow of air is passed through the Faraday shield to remove heat from the Faraday shield
Implementation Method 2
The interface surface is in physical contact with a back side of the Faraday shield, such that the physical contact provides a thermal conduction path from the Faraday shield to the hub
Data Source
AI summary
A chamber is provided. The chamber includes a Faraday shield positioned above a substrate support of the chamber. A dielectric window is disposed over the Faraday shield, and the dielectric window has a center opening. A hub having an internal plenum for passing a flow of fluid received from an input conduit and removing the flow of fluid from an output conduit is further provided. The hub has sidewalls and a center cavity inside of the sidewalls for an optical probe, and the internal plenum is disposed in the sidewalls. The hub has an interface surface that is in physical contact with a back side of the Faraday shield. The physical contact provides for a thermal couple to the Faraday shield at a center region around said center opening, and an outer surface of the sidewalls of the hub are disposed within the center opening of the dielectric window.