Multi-Frequency RF Pulsing for Flexible Plasma Processing
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Solution Overview
Problem
Existing plasma processing technologies for semiconductor wafers are limited in the variety of processes that can be performed due to fixed pulsing frequencies and duty cycles of RF signals.
Innovation Solution
Implementing simultaneous multi-frequency and multi-duty cycle RF pulsing, allowing independent control of pulsing frequencies and duty cycles for multiple RF components, such as TCP coils and bias electrodes, through synchronized or asynchronized pulsing to enhance process flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed pulsing frequencies and duty cycles are used for RF signals, then system simplicity is maintained, but process versatility is limited
Solution Approach 1:
The patent segments the RF signal control into independent controllable units - separate RF generators for TCP coil and bias electrode, each with independent pulsing frequency and duty cycle control. This allows different process parameters to be applied to different components simultaneously, resolving the contradiction between versatility and complexity by modularizing the control system.
Solution Approach 2:
The patent implements dynamic control where pulsing frequencies and duty cycles can be changed during operation without requiring system reconfiguration. The RF generators can operate at different frequencies and duty cycles that are adjustable on-the-fly, enabling process versatility while maintaining system simplicity through software-controlled parameter changes rather than hardware reconfiguration.
2Adaptability or versatility
If independent multi-frequency pulsing is implemented for different RF components, then process flexibility is enhanced, but control synchronization becomes more difficult
Solution Approach 1:
The patent employs feedback mechanisms where the controller monitors the pulsing states of multiple RF generators and adjusts their operation to maintain proper synchronization. The system detects the actual pulsing frequencies and duty cycles being applied and provides feedback control to ensure that processes requiring coordinated pulsing (such as etch and deposit cycles) are properly synchronized, resolving the synchronization difficulty while maintaining flexibility.
Solution Approach 2:
The patent utilizes periodic pulsing patterns where RF generators operate in coordinated cycles - for example, pulsing the TCP coil at one frequency while pulsing the bias electrode at a different frequency, with both synchronized to a common periodic framework. This periodic structure makes synchronization predictable and controllable while still allowing independent frequency and duty cycle selection for each component.
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 a wider range of plasma processing applications by allowing different pulsing frequencies and duty cycles for RF signals, thereby expanding the types of processes that can be performed on semiconductor wafers.
Implementation Method 1
a radio frequency (RF) generator is connected to an impedance matching network... When a process gas is applied to the plasma chamber and an RF signal is supplied from the RF generator... plasma is generated within the plasma chamber
Implementation Method 2
The impedance matching network is connected to a chuck of a plasma chamber... an RF signal is supplied from the RF generator via the impedance matching network to the plasma chamber
Implementation Method 3
plasma is generated within the plasma chamber. The plasma is used to process a semiconductor wafer
Data Source
AI summary
A method for pulsing is described. The method includes generating a first radio frequency (RF) signal, and pulsing a parameter of the first RF signal between a first parameter level and a second parameter level at a pulsing frequency during a cycle of a digital pulsed signal. The method further includes generating a second RF signal, and pulsing a parameter of the second RF signal at a higher pulsing frequency than the pulsing frequency of the parameter of the first RF signal during the cycle. During the cycle, a start time of pulsing the parameter of the first RF signal is synchronized with a start time of pulsing the parameter of the second RF signal and an end time of pulsing the parameter of the first RF signal is synchronized with an end time of pulsing the parameter of the second RF signal.