Harmonic Removal Matching Circuit for Plasma Uniformity
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Solution Overview
Problem
In substrate treating processes, particularly in capacitively coupled plasma reactors, the center-peak phenomenon caused by harmonics with frequencies of 100 MHz or more leads to an imbalance in electron density and plasma density, affecting processing quality and requiring effective harmonic removal.
Innovation Solution
A substrate treating apparatus and method that includes a matching circuit with an impedance matching device and a harmonic removal device, which senses harmonics and adjusts a variable capacitor to remove them, operating in different modes depending on harmonic presence to ensure uniform plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RF power with frequency of 100 MHz or more is applied to generate plasma, then plasma generation efficiency is improved, but harmonics are generated causing center-peak phenomenon and electron density imbalance
Solution Approach 1:
The patent converts the harmful harmonics into a beneficial signal by using them to control a variable capacitor in the matching circuit. The harmonics generated by RF power application are detected and used to adjust the capacitance value, which in turn removes the harmonics and eliminates the center-peak phenomenon, transforming a harmful effect into a useful control mechanism
Solution Approach 2:
The patent implements a feedback mechanism where harmonics generated by RF power are sensed, and this information is used to dynamically adjust the variable capacitor in the matching circuit. The detected harmonic levels feed back to the control system, which modifies the capacitance to remove the harmonics, creating a closed-loop control system that maintains plasma uniformity
2Device complexity
If fixed capacitance value is used in matching circuit, then circuit simplicity is maintained, but plasma uniformity cannot be optimized when harmonics are present
Solution Approach 1:
The patent transforms the static fixed capacitor into a dynamic variable capacitor that can adjust its capacitance value based on detected harmonic levels. This dynamic adjustment allows the matching circuit to adapt to changing plasma conditions and harmonic generation, optimizing plasma uniformity while maintaining operational simplicity through automated control
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the matching circuit from a fixed value to a variable value that can be dynamically adjusted. By varying the capacitance in response to harmonic detection, the system optimizes plasma generation uniformity without requiring complex manual intervention or circuit redesign
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 solution effectively removes harmonics, improves plasma uniformity between the central and edge portions of the substrate, and reduces unnecessary RF power loss by dynamically adjusting the matching circuit based on harmonic presence.
Implementation Method 1
an electromagnetic field is formed in the interior space of a process chamber. The electromagnetic field excites a process gas in the process chamber into plasma
Implementation Method 2
The plasma refers to an ionized gaseous state of matter containing ions, electrons, and radicals. The plasma is generated by very high temperature, a strong electric field, or an RF electromagnetic field
Implementation Method 3
electrons are accelerated by an RF electric field generated between the two electrodes opposite each other, and plasma is generated by ionization by collision of the electrons with a process gas
Implementation Method 4
an impedance matching device that performs impedance matching
Implementation Method 5
a harmonic removal device that removes harmonics caused by the RF power supply... including a first variable capacitor that removes the harmonics
Data Source
AI summary
An apparatus for treating a substrate includes a process chamber having a treatment space therein, a support unit that supports the substrate in the treatment space, a gas supply unit that supplies a process gas into the treatment space, an RF power supply that supplies an RF signal to excite the process gas into plasma, and a matching circuit connected between the RF power supply and the process chamber. The matching circuit includes an impedance matching device that performs impedance matching and a harmonic removal device that removes harmonics caused by the RF power supply. The matching circuit operates in a first mode when the harmonics caused by the RF power supply are sensed and in a second mode when the harmonics caused by the RF power supply are not sensed.