Pulsed Capacitively Coupled Plasma for Independent Ion and Radical Control
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Solution Overview
Problem
Conventional capacitively coupled plasma (CCP) systems face challenges in achieving precise control over plasma parameters due to the inherent coupling of source and bias power, leading to reduced effectiveness of bias power, low ion energy, and limited chemistry control, especially in high aspect ratio etching processes.
Innovation Solution
Implementing staggered multiphased pulsing schemes that independently control ion and radical ratios by applying source and bias power in distinct phases, including a first on phase for plasma generation, a second on phase for etching, and a by-product management phase to optimize plasma parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If source power and bias power are applied simultaneously in conventional CCP systems, then plasma generation and ion acceleration occur together, but the effectiveness of bias power is reduced and ion energy is limited
Solution Approach 1:
The patent segments the plasma processing cycle into distinct phases: a first on phase where source power generates plasma, and a second on phase where bias power accelerates ions. This temporal segmentation decouples the previously simultaneous application of source and bias power, allowing each to function independently at optimal levels without the coupling effects that limited their effectiveness in conventional systems.
Solution Approach 2:
The patent implements periodic pulsing of source and bias power in alternating cycles. The source power is applied during the first on phase to generate plasma, then turned off while bias power is applied during the second on phase to accelerate ions. This periodic action creates distinct temporal windows for plasma generation and ion acceleration, resolving the contradiction by preventing power coupling while maintaining both functions.
2Quantity of substance
If higher source power is used to improve plasma generation, then radical flux increases, but ion energy and chemistry control are compromised
Solution Approach 1:
The patent separates radical generation and ion acceleration into distinct temporal phases. During the first on phase, source power is applied to generate high radical flux without the interfering effects of bias power. During the second on phase, bias power is applied to accelerate ions for precise etching. This segmentation allows optimization of radical flux during plasma generation while maintaining ion energy control during etching, resolving the contradiction between quantity and precision.
Solution Approach 2:
The periodic pulsing scheme allows the system to cycle between high source power (for radical generation) and high bias power (for ion acceleration). By timing these pulses sequentially rather than simultaneously, the patent achieves high radical flux during the source power phase while maintaining precise ion energy control during the bias power phase, thereby improving both radical flux and etching precision.
3Adaptability or versatility
If conventional CCP systems use synchronous power application, then process simplicity is maintained, but control over ion flux and radical flux is limited
Solution Approach 1:
The patent segments the power application into distinct phases with independent control: source power phase for radical flux control and bias power phase for ion flux control. This segmentation enables independent optimization of each parameter without the coupling constraints of synchronous application, significantly improving adaptability and versatility in plasma parameter control despite the added temporal complexity.
Solution Approach 2:
The patent implements dynamic control of power parameters through time-varying pulse widths, amplitudes, and frequencies. The source power and bias power can be independently modulated during their respective phases, allowing real-time adjustment of plasma parameters to optimize performance for different process requirements. This dynamic capability greatly enhances versatility while the modular phase structure manages the complexity of 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
Enhances control over ion flux, radical flux, and plasma chemistry, improving process margin and etching precision in high aspect ratio processes, such as HARC and NAND etches, while maintaining the benefits of CCP systems.
Implementation Method 1
applying a source power (SP) pulse to an SP electrode to generate plasma in a plasma processing chamber
Implementation Method 2
providing a first SP pulse including a first SP power level to an SP electrode to generate a capacitively coupled plasma in a plasma processing chamber
Implementation Method 3
applying a first bias power (BP) pulse to a BP electrode coupled to a target substrate within the plasma processing chamber. The first BP pulse includes a first BP power level and accelerates ions of the plasma toward to target substrate to etch a recess
Implementation Method 4
accelerates ions of the plasma toward to target substrate to etch a recess in an etchable material of the target substrate
Data Source
AI summary
A method of plasma processing includes cyclically performing a cycle including the steps of performing a glow phase and performing an afterglow phase. The glow phase includes providing a first SP pulse comprising a first SP power level for a first duration to an SP electrode to generate a capacitively coupled plasma in a plasma processing chamber. The first SP pulse terminates at the end of the glow phase. The afterglow phase is performed after the glow phase and includes providing a BP pulse train to a BP electrode coupled to a target substrate within the plasma processing chamber in an afterglow of the capacitively coupled plasma for a second duration between about 10 μs and about 100 μs. The BP pulse train includes a plurality of BP spikes. Each of the plurality of BP spikes is a DC pulse that has a first BP power level.