Matchless Plasma Source With Reactive Resonance for Fast Ignition
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Solution Overview
Problem
Existing plasma systems for semiconductor wafer fabrication are limited by high costs, slow plasma ignition and impedance tuning, limited pulse capabilities, and poor plasma uniformity due to the use of RF generators, RF cables, and RF matches, which restrict future process capabilities.
Innovation Solution
A matchless plasma source using low impedance voltage sources, such as FETs or IGBTs, operates in a half-bridge configuration to deliver RF power directly to excitation electrodes, eliminating the need for RF generators and cables, and employs a reactive circuit to achieve high-quality factor resonance for instantaneous plasma ignition and sustainment, with agile DC rail control for arbitrary pulse shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF generators, RF cables, and RF matches are used to deliver power to the plasma chamber, then the system can provide stable RF power, but the cost increases, plasma ignition speed decreases, and impedance tuning becomes slower
Solution Approach 1:
The patent extracts and eliminates the RF match and RF cable from the traditional RF power delivery system. By using a solid-state power amplifier with a low-impedance voltage source directly coupled to the plasma chamber, the system removes the impedance matching network and transmission line, thereby reducing cost and complexity while maintaining stable power delivery
Solution Approach 2:
The patent replaces the mechanical/electrical RF match box and RF cable system with an electronic solid-state power amplifier system. This substitution uses electronic circuitry (FETs, IGBTs, and associated control circuits) to directly generate and deliver the RF power signal to the plasma chamber, eliminating the need for physical impedance matching components
2Power
If RF matches and cables are used in the power delivery system, then power can be transmitted to the plasma chamber, but the speed of plasma ignition and impedance tuning becomes slow
Solution Approach 1:
The patent replaces the slow mechanical/electrical RF match system with a fast electronic solid-state power amplifier system. The solid-state amplifier can rapidly adjust its output impedance and power level through electronic control signals, enabling fast plasma ignition and real-time impedance tuning without the delays inherent in traditional RF matching networks
Solution Approach 2:
The patent implements a dynamic power delivery system using a solid-state amplifier with electronically controllable output impedance. The system can rapidly change its operating parameters in response to plasma conditions, enabling fast ignition and adaptive impedance matching through real-time electronic adjustment rather than fixed or slowly-adjustable mechanical components
3Productivity
If traditional RF power delivery systems are used, then plasma can be generated in the chamber, but pulse capabilities are limited and plasma uniformity is poor
Solution Approach 1:
The patent implements dynamic pulse capabilities through the solid-state power amplifier's ability to rapidly modulate its output power and impedance. The system can generate arbitrary pulse shapes, adjust duty cycles, and adapt to changing plasma conditions in real-time, providing superior versatility compared to traditional continuous-wave RF systems with limited pulse functionality
Solution Approach 2:
The patent utilizes real-time parameter adjustment of the RF power signal through the solid-state amplifier. By dynamically changing frequency, power level, pulse width, and impedance parameters, the system can optimize plasma generation for different process requirements and improve plasma uniformity across the wafer surface through adaptive control
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 approach reduces costs, enhances plasma ignition speed, improves impedance tuning, and enables advanced pulse capabilities, resulting in more efficient and uniform plasma processing for semiconductor wafer fabrication.
Implementation Method 1
employs a reactive circuit to achieve high-quality factor resonance for instantaneous plasma ignition and sustainment
Implementation Method 2
RF power is coupled to the electrode using power transistors, such as field-effect transistors (FETs) or insulated-gate bipolar transistors (IGBTs), that are operated as a low impedance voltage source to couple power to the electrode
Implementation Method 3
An RF power is provided via the RF cable and the RF match to the plasma chamber in which a wafer is processed. Also, one or more gases are supplied to the plasma chamber and upon reception of the RF power, plasma is generated within the plasma chamber
Data Source
AI summary
A matchless plasma source is described. The matchless plasma source includes a controller that is coupled to a direct current (DC) voltage source of an agile DC rail to control a shape of an amplified square waveform that is generated at an output of a half-bridge transistor circuit. The matchless plasma source further includes the half-bridge transistor circuit used to generate the amplified square waveform to power an electrode, such as an antenna, of a plasma chamber. The matchless plasma source also includes a reactive circuit between the half-bridge transistor circuit and the electrode. The reactive circuit has a high-quality factor to negate a reactance of the electrode. There is no radio frequency (RF) match and an RF cable that couples the matchless plasma source to the electrode.