Ion Current Compensation for Plasma Etching Precision
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Solution Overview
Problem
Current plasma processing technologies face challenges in achieving a narrow ion energy distribution, which is essential for precise etching and deposition processes, as existing methods are expensive, inefficient, and difficult to control, often adversely affecting plasma density.
Innovation Solution
A system comprising a power supply that provides a periodic voltage function with pulses and a ramp voltage between pulses, coupled with an ion current compensation component to adjust the slope of the voltage function, allowing for controlled ion energy distribution by modulating the negative voltage step and adjusting the compensation current to achieve desired ion energy peaks and fractions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sinusoidal AC voltage is applied to the substrate to induce voltage on the surface, then ions can be attracted toward the negatively-charged surface for etching, but this produces a broad distribution of ion energies which limits the ability to achieve desired etch profile
Solution Approach 1:
The patent applies periodic voltage pulses instead of continuous sinusoidal AC voltage. The pulsed waveform creates distinct ion acceleration phases, allowing ions to be accelerated to specific energy levels during the pulse duration while minimizing the broad energy distribution caused by continuous sinusoidal variation. This periodic pulsed action enables better control over ion energy distribution for precise etching.
Solution Approach 2:
The patent dynamically adjusts voltage parameters including applying negative voltage steps between pulses and using ion current compensation to modify the voltage waveform in real-time. This dynamic control allows the system to optimize ion energy distribution continuously, narrowing the energy spread while maintaining effective ion attraction to the substrate surface for precise etching profiles.
2Manufacturing precision
If known techniques are used to achieve a narrow ion energy distribution, then etching precision may be improved, but these techniques are expensive, inefficient, difficult to control, and may adversely affect plasma density
Solution Approach 1:
The patent implements ion current compensation where the system automatically adjusts the voltage waveform based on detected ion current. The ion current detection circuit monitors the actual ion current and feeds this information back to modify the voltage waveform in real-time, creating a self-regulating system that narrows ion energy distribution without requiring complex external control equipment. This self-service approach reduces system complexity and cost while improving precision.
Solution Approach 2:
The patent changes key voltage parameters including applying negative voltage steps between pulses, adjusting pulse duration and amplitude, and modifying the waveform shape through ion current compensation. These parameter changes enable narrow ion energy distribution using standard plasma processing equipment, avoiding the need for expensive specialized techniques while maintaining control precision.
3Manufacturing precision
If a non-varying negative voltage is applied to the substrate, then ions impact the substrate with substantially the same energy, but this is ineffective for dielectric substrates that require voltage induction on the surface
Solution Approach 1:
The patent uses periodic voltage pulses with negative voltage steps between pulses to create the necessary voltage induction on dielectric substrate surfaces. The pulsed nature allows electrons to accumulate during the positive phase, creating negative surface charge that attracts ions, while the negative voltage step between pulses provides the uniform energy condition needed for precise etching. This periodic action bridges the gap between dielectric substrate requirements and ion energy uniformity.
Solution Approach 2:
The patent dynamically controls the voltage waveform to adapt to different substrate types. For dielectric substrates, the system applies AC-induced voltage with negative steps; for conductive substrates, it can apply more uniform negative voltage. This dynamic adaptability allows the same system to achieve both ion energy uniformity and effective voltage induction across different substrate materials.
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 a controlled and efficient ion energy distribution, improving the precision of plasma processing without significantly affecting plasma density, thus enhancing the etching and deposition processes.
Implementation Method 1
a power supply 102 configured to apply a periodic voltage function to a substrate support 108
Implementation Method 2
an ion current compensation component 1260 configured to provide a compensation current, Ic, to modify a slope, dV0/dt, of the fourth portion 1408
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
Implementation Method 5
the surface of the substrate will be charged negatively, which causes ions to be attracted toward the negatively-charged surface
Data Source
AI summary
Systems, methods and apparatus for regulating ion energies in a plasma chamber and chucking a substrate to a substrate support are disclosed. An exemplary method includes placing a substrate in a plasma chamber, forming a plasma in the plasma chamber, controllably switching power to the substrate so as to apply a periodic voltage function (or a modified periodic voltage function) to the substrate, and modulating, over multiple cycles of the periodic voltage function, the periodic voltage function responsive to a defined distribution of energies of ions at the surface of the substrate so as to effectuate the defined distribution of ion energies on a time-averaged basis.