Switch-Mode Bias Waveforms for Narrow Ion Energy Distribution
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Solution Overview
Problem
Existing plasma processing techniques struggle to achieve a narrow ion energy distribution efficiently and cost-effectively, particularly for dielectric substrates, as sinusoidal waveforms induce broad distributions, affecting plasma density and process control.
Innovation Solution
A switch-mode power supply system is employed to generate controlled waveforms on the substrate, using switch-mode bias supply and switch components to apply peak and ramped voltages, enabling precise ion energy distribution without significantly impacting plasma density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sinusoidal waveform is applied to the substrate, then the substrate attracts electrons during the positive half cycle, but this induces a broad distribution of ion energies
Solution Approach 1:
The patent applies periodic voltage pulses with specific timing characteristics to the substrate. By controlling the pulse width, amplitude, and frequency, the system creates distinct electron attraction phases followed by controlled ion bombardment phases, achieving narrow ion energy distribution while maintaining effective electron collection during the periodic cycles
Solution Approach 2:
The system dynamically adjusts voltage parameters in real-time based on process requirements. The voltage waveform transitions from static sinusoidal to dynamic pulsed waveforms with variable characteristics, allowing optimization of both electron attraction and ion energy control during different process stages
2Manufacturing precision
If known techniques are used to achieve a narrow ion energy distribution, then ion energy control improves, but the system becomes expensive and inefficient
Solution Approach 1:
The patent achieves narrow ion energy distribution by changing the voltage waveform parameters (pulse width, amplitude, frequency, duty cycle) rather than using complex hardware modifications. This software-controlled parameter adjustment provides precise ion energy control through standard plasma processing equipment, reducing system complexity and cost
Solution Approach 2:
The system replaces complex mechanical or hardware-based ion energy control mechanisms with electronically controlled voltage waveform generation. The use of software-defined pulse waveforms substitutes for expensive specialized hardware, achieving the same control function more efficiently
3Manufacturing precision
If techniques to achieve narrow ion energy distribution are applied, then etching precision improves, but plasma density is adversely affected
Solution Approach 1:
The periodic pulsed waveform creates distinct phases where electron generation occurs during the positive pulse (maintaining plasma density) and ion bombardment occurs during the negative pulse or pulse trailing edge (achieving narrow ion energy distribution). This temporal separation allows both high plasma density and precise ion energy control to coexist
Solution Approach 2:
The system applies preliminary voltage pulses to generate and condition the plasma before the main ion bombardment phase. This preliminary action ensures sufficient plasma density is established prior to ion acceleration, allowing precise ion energy control without compromising the plasma medium
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
The system achieves a narrow and controlled ion energy distribution, enhancing etching precision and efficiency while reducing energy costs and material expenses, and minimizing interference with plasma density.
Implementation Method 1
A switch-mode power supply system is employed to generate controlled waveforms on the substrate, using switch-mode bias supply and switch components to apply peak and ramped voltages
Implementation Method 2
an AC voltage (e.g., high frequency) may be applied to the conductive plate (or chuck) so that the AC field induces a voltage on the surface of the substrate
Implementation Method 3
the surface of the substrate will be charged negatively, which causes ions to be attracted toward the negatively-charged surface. And when the ions impact the surface of the substrate, the impact dislodges material from the surface of the substrate-effectuating the etching
Data Source
AI summary
An apparatus and method to produce a waveform. The apparatus includes a first node, at least one switch that couples a second node to the first node, and responsive to the at least one switch being closed, a peak voltage is produced at the first node before a voltage at the first node drops by a voltage step. A power supply is coupled to the first node to produce, after the voltage step, a ramped voltage at the first node.