Tuning Electrode Impedance for Plasma Uniformity and Stress Control
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Solution Overview
Problem
Current plasma processing chambers face challenges in achieving uniformity of film thickness and controlling film stress during plasma deposition processes, particularly from the center to the edge of substrates.
Innovation Solution
A plasma processing apparatus with a tuning electrode electrically coupled to a variable capacitor and an inductor, allowing for adjustment of high frequency RF impedance and termination of low frequency RF to ground, which modulates the plasma profile and film stress by varying capacitance and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing chambers are used, then the deposition process can be performed, but center to edge thickness uniformity deteriorates
Solution Approach 1:
The patent applies local quality by implementing a non-uniform plasma distribution through the tuning electrode structure. The electrode is divided into multiple segments (e.g., center region, intermediate regions, edge regions) that can be independently tuned to create localized plasma density variations. This allows different regions of the substrate to receive optimized plasma flux, improving center-to-edge thickness uniformity by addressing each region's specific deposition requirements rather than using a uniform approach across the entire chamber.
Solution Approach 2:
The patent implements dynamics by using variable capacitors and inductors connected to each electrode segment, allowing real-time adjustment of RF impedance and plasma distribution. The tuning electrodes can be dynamically adjusted during or between deposition cycles to optimize plasma uniformity for different substrate sizes, materials, and deposition conditions. This dynamic control enables adaptation to varying process requirements, improving both uniformity and operational flexibility.
2Manufacturing precision
If conventional plasma processing chambers are used, then the deposition process can be performed, but film stress control deteriorates
Solution Approach 1:
The patent applies parameter changes by utilizing variable capacitors and inductors to adjust the RF impedance of each electrode segment independently. By changing the capacitance and inductance values, the plasma density, ion flux, and deposition rate can be precisely controlled in different regions. This parameter adjustment capability enables fine-tuning of film stress characteristics, allowing the deposition of films with controlled stress states (tensile or compressive) to meet specific application requirements.
Solution Approach 2:
The patent implements feedback mechanisms through the tunable RF matching network connected to each electrode segment. The variable capacitors and inductors allow real-time adjustment of RF power delivery based on plasma conditions, creating a feedback loop that maintains optimal plasma parameters. This feedback control enables precise management of film stress by adjusting plasma conditions during deposition, compensating for variations in gas flow, temperature, and other process parameters.
3Manufacturing precision
If tuning electrode with variable capacitor and inductor is added, then RF impedance can be optimized and plasma profile controlled, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the tuning electrode system to perform multiple functions simultaneously. The same electrode structure with variable capacitors and inductors is used to control both plasma uniformity and film stress, as well as to match RF impedance across different operating conditions. This multi-functional approach allows a single device configuration to address multiple process requirements (uniformity, stress control, power coupling efficiency) without requiring separate specialized components for each function, thereby reducing overall system complexity despite the added tuning capabilities.
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 improves center-to-edge thickness uniformity and film stress control by optimizing the RF fields and plasma distribution, enhancing deposition uniformity and stress management.
Implementation Method 1
a first capacitor electrically coupled to the tuning electrode
Implementation Method 2
an inductor configured in parallel with the first capacitor
Implementation Method 3
an inductor configured in parallel with the first capacitor
Data Source
AI summary
Embodiments of the present invention relate to apparatus for improving uniformity and film stress of films deposited during plasma process of a substrate. According to embodiments, the apparatus includes a tuning electrode and/or a tuning ring electrically coupled to a variable capacitor for tuning high frequency RF impedance of the electrode and a low frequency RF termination to ground. The plasma profile and resulting film thickness can be controlled by adjusting the capacitance of the variable capacitor and the resulting impedance of the tuning electrode. The film stress of the film deposited on the substrate can be controlled, i.e., increased, by terminating the low frequency RF during processing.