Plasma Showerhead Faraday Shield for Uniform Film Deposition
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Solution Overview
Problem
Achieving uniform film thickness across large substrates in high density plasma chambers is challenging due to parasitic plasma formation caused by RF power, which leads to non-uniform deposition and potential contamination from film deposition on surfaces outside the process volume.
Innovation Solution
Incorporating a faraday shield with angled electrodes between the inductive coupler and the gas volume to reduce the electric field and prevent parasitic plasma formation, while maintaining magnetic flux for substrate processing, thereby allowing higher RF power usage without increasing parasitic plasma formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF power is increased to improve plasma generation and film deposition, then productivity and deposition rate improve, but parasitic plasma formation increases causing non-uniform film thickness
Solution Approach 1:
A Faraday shield is introduced as an intermediary component between the inductive coupler and the process volume. The shield comprises a grounded conductive layer that intercepts and redirects RF electric field lines, preventing them from directly coupling into regions where parasitic plasma would form. This mediator allows high RF power to be applied for high deposition rates while blocking the harmful electric field components that cause non-uniform plasma distribution.
Solution Approach 2:
The invention modifies the RF field distribution parameters by introducing the Faraday shield, which changes the electric field topology. The shield transforms the RF field from a configuration that allows capacitive coupling and parasitic plasma into one where the field is confined to the intended process region. This parameter change enables operating at higher RF powers without the detrimental effects on film uniformity.
2Productivity
If RF power is increased to improve processing efficiency, then throughput increases, but parasitic plasma causes contamination outside the process volume
Solution Approach 1:
The Faraday shield converts the harmful RF electric field that causes parasitic plasma into a beneficial confined field distribution. By strategically placing the grounded conductive shield, the RF field energy that would otherwise create harmful parasitic plasma is redirected and confined to the intended process volume, allowing high power operation without contamination.
Solution Approach 2:
The Faraday shield acts as an intermediary barrier that selectively interacts with RF electric field lines. It allows the beneficial magnetic field components needed for plasma generation to pass through while blocking the harmful electric field components that would cause parasitic plasma and contamination in surrounding areas.
3Manufacturing precision
If a Faraday shield is added to reduce parasitic plasma, then film uniformity improves, but device complexity increases
Solution Approach 1:
The Faraday shield is implemented as a segmented structure with multiple independent conductive elements or panels rather than a single complex component. This segmentation allows for easier manufacturing, installation, and adjustment, reducing the overall complexity increase while maintaining the plasma uniformity benefits.
Solution Approach 2:
The Faraday shield structure is designed to serve multiple functions: it acts as an RF field barrier, provides structural support for the inductive coupler, and can be integrated with existing chamber components. This multi-functionality reduces the need for additional separate components, thereby minimizing the increase in device complexity.
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 solution enables uniform film deposition across large substrates by reducing parasitic plasma, increasing the RF power threshold, and minimizing substrate contamination, leading to improved processing efficiency and throughput.
Implementation Method 1
The precursor gas in the chamber is energized (e.g., excited) into a plasma by applying a single or array of radio frequency (RF) antennas inductively coupled to the precursor gas to form the plasma
Implementation Method 2
Incorporating a faraday shield with angled electrodes between the inductive coupler and the gas volume to reduce the electric field and prevent parasitic plasma formation, while maintaining magnetic flux for substrate processing
Data Source
AI summary
The present disclosure is directed to a showerhead for distributing plasma. The showerhead includes a perforated tile coupled to a support structure. A dielectric window is disposed over the perforated tile. An electrode is coupled to the dielectric window. An inductive coupler is disposed over the dielectric window. At least a portion of the inductive coupler is angled relative to at least a portion of the electrode.