Pulsed Waveform Control for Narrow Ion Energy Distribution
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Solution Overview
Problem
Current plasma processing techniques struggle to achieve a narrow ion energy distribution, which is essential for precise etching profiles, due to the broad distribution induced by sinusoidal waveforms, and existing solutions are costly, inefficient, and difficult to control, adversely affecting plasma density.
Innovation Solution
A system comprising a switch-mode power supply that applies a periodic voltage function with pulses and a portion between pulses, adjusted by a controller to modify the current slope, allowing for precise control of ion energy distribution without significantly impacting plasma density, using inexpensive and efficient components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
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 which limits the ability to achieve desired etch profiles
Solution Approach 1:
The patent applies periodic voltage pulses instead of continuous sinusoidal waveforms. The controller delivers pulsed voltage to the substrate, creating periodic electron attraction events that result in a concentrated ion energy distribution at specific energy levels, thereby achieving precise etch profiles while maintaining effective electron attraction during the pulse periods
Solution Approach 2:
The patent dynamically adjusts the voltage waveform parameters including pulse width, frequency, and amplitude through the controller. This dynamic control allows optimization of both electron attraction effectiveness and ion energy concentration, resolving the contradiction between quantity of electron attraction and precision of etch profile
2Manufacturing precision
If known techniques are used to achieve a narrow ion energy distribution, then etch profile precision is improved, but these techniques are expensive, inefficient, difficult to control, and may adversely affect plasma density
Solution Approach 1:
The patent changes the voltage waveform parameters (from sinusoidal to pulsed) and controls pulse characteristics (width, frequency, amplitude) to achieve narrow ion energy distribution. This parameter-based control approach is simpler and more efficient than complex hardware modifications, allowing precise ion energy control without adversely affecting plasma density
Solution Approach 2:
The controller monitors and adjusts voltage pulse parameters in real-time to maintain optimal ion energy distribution. This feedback control enables precise and simple control of the pulsed voltage application, achieving narrow ion energy distribution without complex device architecture
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 solution enables a concentrated or bi-modal ion energy distribution, achieving precise etching profiles with improved efficiency and reduced energy costs by controlling ion energies and maintaining plasma density, thus overcoming the limitations of existing technologies.
Implementation Method 1
a first power supply providing a periodic voltage function to an electrical node, the periodic voltage function including pulses and a portion between the pulses
Implementation Method 2
a second power supply providing current to modify a slope of the portion between the pulses
Implementation Method 3
when the ions impact the surface of the substrate, the impact dislodges material from the surface of the substrate effectuating the etching
Implementation Method 4
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
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.