Plasma Electrode Bias Timing for Uniform Ion Energy in Etching
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Solution Overview
Problem
The increasing integration density and aspect ratios of semiconductor devices pose challenges in semiconductor manufacturing processes, particularly in forming microstructures with high reliability, as existing methods struggle to efficiently manage the complexities of reduced linewidths and increased aspect ratios.
Innovation Solution
A semiconductor processing apparatus is designed with a process chamber, a lower electrode, and an upper electrode, utilizing a combination of low-frequency, high-frequency, and direct-current power generators to control and vary signals, generating plasma for processes like etching, which includes a high-frequency signal turned off during parts of a low-frequency signal duration and a DC bias applied to the upper electrode, optimizing energy distribution and ion acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-frequency power generation is used, then device complexity is reduced, but manufacturing precision deteriorates due to inability to control ion energy distribution uniformly
Solution Approach 1:
The power generation system is segmented into multiple independent power generators operating at different frequencies (first power generator at frequency f1, second power generator at frequency f2, third power generator at frequency f3). Each generator independently controls specific aspects of the plasma process, allowing precise control of ion energy distribution without requiring a single complex generator to handle all functions simultaneously.
Solution Approach 2:
The patent employs periodic switching between different frequency signals in a cyclic manner. The first power generator operates during a first cycle, the second power generator operates during a second cycle, and the third power generator operates during a third cycle. This periodic action allows the system to achieve uniform ion energy distribution by alternating between different frequency regimes, improving manufacturing precision while maintaining manageable device complexity.
2Manufacturing precision
If high-frequency signal is continuously applied, then plasma generation is maintained, but ion energy distribution becomes non-uniform causing bowing phenomenon
Solution Approach 1:
The system implements periodic switching between different frequency power generators to prevent continuous high-frequency signal application. The first power generator (frequency f1) operates during a first cycle, then switches to the second power generator (frequency f2) during a second cycle, and subsequently to the third power generator (frequency f3) during a third cycle. This periodic action redistributes ion energy uniformly, eliminating the bowing phenomenon while maintaining plasma generation and process reliability.
Solution Approach 2:
The patent changes the frequency parameter of the applied power signal by switching between multiple distinct frequencies (f1, f2, f3) across different operational cycles. This parameter change allows the system to optimize ion energy distribution at different stages of the process, preventing the bowing phenomenon that occurs with continuous single-frequency application, while maintaining stable plasma generation for reliable processing.
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 enhances the reliability of semiconductor processing by ensuring uniform energy distribution of ions and reducing the bowing phenomenon, thereby improving the precision and reliability of semiconductor manufacturing processes.
Implementation Method 1
a process chamber having an inner space configured to perform a process using plasma
Data Source
AI summary
A semiconductor processing apparatus includes an upper electrode and a substrate on a lower electrode disposed inside the process chamber, a first power generator configured to provide a low-frequency signal to the lower electrode, wherein the low-frequency signal varies between a reference voltage and a first voltage at intervals of a first cycle, a second power generator configured to provide a high-frequency signal to the lower electrode, wherein the high-frequency signal has a sinusoidal waveform that oscillates at intervals of a second cycle shorter than the first cycle, and a direct-current (DC) power generator configured to provide a DC bias to the upper electrode. The high-frequency signal is turned off during at least part of a duration for which the low-frequency signal has the first voltage, and the high-frequency signal is turned on and turned off at intervals of a third cycle different from the first and second cycles.