RF-Powered Faraday Shield for Cleaner ICP Dielectric Windows
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Substrate processing systems face challenges with nonvolatile byproducts depositing on dielectric windows during etching of piezoelectric films like PZT, leading to process drift and reduced repeatability, necessitating improved methods to enhance mean time between cleans and chamber recovery.
Innovation Solution
Incorporation of an RF-powered Faraday shield between the coil and dielectric window in a substrate processing system, coupled with a tuning circuit and capacitors to adjust voltage standing waves, reduces byproduct deposition by uniformizing ion energy across the window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If inductively-coupled plasma is generated by coils adjacent to a dielectric window, then plasma is created for etching, but nonvolatile byproducts are deposited on the dielectric window causing process drift
Solution Approach 1:
A Faraday shield is introduced as an intermediary component between the coil and the dielectric window. The shield is RF-powered and creates a modified electromagnetic field distribution that reduces ion bombardment energy at the window surface, thereby minimizing byproduct deposition while maintaining plasma generation for etching
Solution Approach 2:
The invention changes the RF power parameters by introducing a separate RF power source for the Faraday shield, allowing independent control of the shield's RF power from the coil's RF power. This parameter separation enables optimization of ion energy distribution to reduce deposition while maintaining etching effectiveness
2Power
If RF power is supplied to the coil for plasma generation, then etching process is enabled, but voltage standing waves cause non-uniform ion energy distribution
Solution Approach 1:
The Faraday shield acts as a field-modifying intermediary that redistributes the RF electromagnetic field within the processing chamber. By adjusting the shield's RF power and coupling, the voltage standing wave pattern is modified to achieve more uniform ion energy distribution across the substrate surface
Solution Approach 2:
The system dynamically adjusts RF power distribution between the coil and Faraday shield to optimize plasma uniformity. The RF-powered Faraday shield provides dynamic control over field distribution, allowing adaptation to different process conditions to maintain uniform ion energy
3Productivity
If the dielectric window is used for plasma generation, then inductively-coupled plasma is achieved, but chamber recovery time increases due to deposition buildup
Solution Approach 1:
The RF-powered Faraday shield provides preliminary protection against byproduct deposition by modifying the ion energy distribution before ions reach the dielectric window. This preventive action reduces the rate of deposition buildup, thereby extending the mean time between cleans and reducing chamber recovery time
Solution Approach 2:
The invention converts the harmful effect of RF coupling to the dielectric window into a beneficial effect. By using the Faraday shield to capture and redistribute RF energy, the system reduces direct RF coupling to the window, thereby minimizing deposition while maintaining plasma generation efficiency
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 RF-powered Faraday shield significantly reduces deposition on the dielectric window, improving process performance and repeatability by minimizing RF coupling and maintaining uniform ion energy during etching.
Implementation Method 1
An RF generator is configured to supply RF power to the coil
Implementation Method 2
A Faraday shield is arranged between the coil and the dielectric window
Implementation Method 3
Etching usually includes either wet chemical etching or dry etching. Dry etching may be performed using plasma generated by inductively-coupled plasma (ICP)
Implementation Method 4
a capacitor is connected to one of the coil and the Faraday shield to adjust a position of a voltage standing wave along the coil
Data Source
AI summary
A substrate processing system includes a processing chamber including a dielectric window and a substrate support arranged therein to support a substrate. A coil is arranged outside of the processing chamber adjacent to the dielectric window. A Faraday shield is arranged between the coil and the dielectric window. An RF generator is configured to supply RF power to the coil. The coil is coupled by stray capacitance and/or directly coupled to the Faraday shield. A capacitor is connected to one of the coil and the Faraday shield to adjust a position of a voltage standing wave along the coil.