Substrate Chamber 2-Port Impedance Measurement for Plasma Control
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Solution Overview
Problem
Existing impedance measurement methods for substrate processing chambers are not precise enough to effectively control plasma and maintain chamber characteristics consistently.
Innovation Solution
A method for calculating 2-port impedance of a substrate processing chamber by setting RF and edge electrodes as input/output terminals for various frequencies, using an impedance matching circuit and edge impedance control circuit with variable elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional impedance measurement methods using a probe are used in a plasma state, then impedance can be measured, but measurement precision is insufficient for precise plasma control
Solution Approach 1:
The patent applies preliminary action by measuring impedance in advance before plasma generation. The system measures impedance at multiple frequencies (e.g., 13.56 MHz and harmonics) before turning on the plasma, allowing the controller to pre-determine appropriate power supply parameters. This preliminary measurement ensures measurement precision while enabling reliable plasma control, as the impedance data is obtained without plasma interference that would otherwise compromise measurement accuracy.
2Adaptability or versatility
If impedance is measured only at a single frequency, then measurement is simple, but adaptability to various plasma processing conditions is limited
Solution Approach 1:
The patent implements universality by designing the impedance measurement system to operate at multiple frequencies simultaneously. The measurement device can measure impedance at the fundamental frequency (13.56 MHz) and harmonic frequencies, making the system adaptable to various plasma processing conditions and equipment configurations. This multi-frequency capability provides universal applicability across different plasma scenarios while the integrated controller manages the complexity, preventing device complexity from becoming a limiting factor.
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
Enables precise impedance measurement for various frequencies and chamber states, allowing for better plasma control and maintenance of chamber characteristics.
Implementation Method 1
an radio frequency (RF) electrode receiving RF power for generating plasma
Implementation Method 2
The RF electrode is connected to a RF power supply via an impedance matching circuit, so that the RF power is supplied to the RF electrode
Implementation Method 3
an edge impedance control circuit including variable impedance elements, so that impedance of a peripheral portion of the support unit is adjusted
Data Source
AI summary
Disclosed are an impedance measurement method capable of measuring impedance of a chamber in various aspects and a control device configured to perform impedance measurement. A substrate processing apparatus includes a chamber and a support unit disposed in the chamber to support a substrate. An RF electrode receiving RF power for generation of plasma and an edge electrode provided outside the substrate are disposed on the support unit. The RF electrode is connected to an RF power supply, thereby supplying the RF power to the RF electrode. The edge electrode is connected to an edge impedance control circuit, thereby adjusting impedance of a peripheral portion of the support unit. The impedance measurement method includes calculating 2-port impedance of the chamber by setting the RF electrode and the edge electrode as 2-port input terminals and 2-port output terminals for various frequencies and storing data on the 2-port impedance of the chamber.