Plasma Bias Assembly Using Pulsed Voltage for IEDF Control
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Solution Overview
Problem
Conventional plasma processing methods struggle to maintain a constant sheath voltage and control the ion energy distribution function (IEDF) effectively, leading to undesirable etch profiles and arcing issues in high aspect ratio feature formation during semiconductor manufacturing.
Innovation Solution
A plasma processing chamber design incorporating a pulsed-voltage waveform generator and filter assemblies to deliver a pulsed-voltage signal and an RF signal to the biasing electrode, maintaining a nearly constant sheath voltage and controlling the IEDF through a substrate support assembly with dielectric layers, thereby enhancing feature profile control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional RF bias is used to achieve higher self-bias voltages, then ion acceleration towards substrate is improved, but ion energy distribution becomes uncontrolled leading to bowing of etched feature walls
Solution Approach 1:
The patent applies periodic pulsed voltage to the substrate instead of continuous RF bias. By controlling the pulse width, frequency, and duty cycle, the system achieves high self-bias voltages while maintaining a more uniform ion energy distribution. The pulsed nature allows ions to accelerate during the pulse and reset during the off-period, preventing the energy spread that causes wall bowing in conventional continuous RF bias systems.
Solution Approach 2:
The system dynamically adjusts voltage parameters in real-time by switching between pulsed and continuous modes, and by varying pulse characteristics. This dynamic control enables optimization of ion energy distribution during different process stages, achieving both high self-bias for deep etching and precise control for profile accuracy, resolving the trade-off between power delivery and manufacturing precision.
2Manufacturing precision
If multiple RF sources are used to control plasma properties, then plasma density and ion energy control is improved, but RF current cross-talk between sources increases causing power diversion and potential damage
Solution Approach 1:
The patent introduces a pulsed voltage source as an intermediary between the RF sources and the substrate. This pulsed source controls the substrate bias independently, allowing the RF sources to focus on plasma generation and chemistry control without interfering with each other through substrate current cross-talk. The pulsed voltage acts as a mediator that decouples the control functions, improving both plasma property control and RF source stability.
Solution Approach 2:
The system segments the control functions by separating plasma generation (handled by RF sources) from substrate biasing (handled by pulsed voltage source). This functional segmentation allows each source to operate independently at its optimal parameters without causing cross-talk, enabling precise control of plasma properties while maintaining RF source reliability.
3Power
If lower frequency RF bias is used to achieve higher self-bias voltages, then ion acceleration energy is improved, but difference in energy between IEDF peaks increases causing isotropic etching and mask sputtering
Solution Approach 1:
By using pulsed voltage with controlled duty cycle, the system delivers high ion acceleration energy during the pulse phase while minimizing the off-period to reduce low-energy ion effects. This temporal separation allows high self-bias for deep etching without prolonged exposure to conditions that cause mask sputtering and isotropic etching, resolving the contradiction between ion acceleration energy and harmful side effects.
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 enables precise control over the IEDF and etch profile, reducing arcing and improving the reliability of high aspect ratio feature formation in semiconductor manufacturing.
Implementation Method 1
The application of RF voltage to the power electrode causes an electron-repelling plasma sheath (also referred to as the 'cathode sheath') to form over a processing surface of a substrate
Implementation Method 2
ions from the plasma are accelerated towards a surface of a substrate to form openings in a material layer
Implementation Method 3
ions from the plasma are accelerated towards a surface of a substrate to form openings in a material layer disposed beneath a mask layer
Data Source
AI summary
Embodiments of the disclosure provided herein include an apparatus and method for the plasma processing of a substrate in a processing chamber. More specifically, embodiments of this disclosure describe a biasing scheme that is configured to provide a radio frequency (RF) generated RF waveform from an RF generator to one or more electrodes within a processing chamber and a pulsed-voltage (PV) waveform delivered from one or more pulsed-voltage (PV) generators to the one or more electrodes within the processing chamber. The plasma process(es) disclosed herein can be used to control the shape of an ion energy distribution function (IEDF) and the interaction of the plasma with a surface of a substrate during plasma processing.