Tunable Plasma Chamber Shield for Ion Energy and Uniformity Control
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Solution Overview
Problem
Plasma processing tools face challenges in achieving high plasma uniformity and control over plasma profile, density, and ion energy, particularly in removing difficult materials like photoresists and hard surface layers, and in providing isotropic etching with varying ion energies.
Innovation Solution
A plasma processing apparatus with an inductive coupling element, an electrostatic shield connected through tunable reactive impedance circuits, allowing adjustment of RF voltage and plasma potential to achieve a wide range of plasma conditions suitable for etching and deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional plasma sources are used, then plasma generation is achieved, but control over plasma profile, density, and ion energy is limited
Solution Approach 1:
The patent implements dynamic control of plasma characteristics by making the plasma potential可调 (tunable) through a variable impedance circuit connected to an electrostatic shield. This allows the plasma to transition between different operational modes (capacitive, inductive, hybrid) and adjust ion energy independently, providing dynamic adaptability without requiring multiple separate plasma sources.
Solution Approach 2:
The patent changes key plasma parameters (potential, density, ion energy) by adjusting the impedance of the electrostatic shield through a variable capacitor or inductor. By changing the reactance value, the system can achieve parallel resonance conditions that dramatically alter plasma characteristics, enabling precise control over etching and deposition processes.
2Productivity
If high ion energy is used for removing difficult materials, then material removal efficiency improves, but plasma uniformity deteriorates
Solution Approach 1:
The patent applies different plasma characteristics to different regions by using the tunable electrostatic shield to create localized potential adjustments. The shield can be positioned and impedance-controlled to affect specific areas of the plasma, allowing high ion energy to be applied where needed for difficult material removal while maintaining uniformity in other regions for precision processing.
Solution Approach 2:
The system dynamically adjusts plasma properties during processing by changing the impedance of the electrostatic shield. This allows the plasma to transition between high-ion-energy modes for breakthrough of hard layers and uniform low-energy modes for precise etching, maintaining both productivity and manufacturing precision through temporal dynamics.
3Manufacturing precision
If isotropic etching is performed with varying ion energies, then etching quality improves, but control precision becomes more difficult
Solution Approach 1:
The patent incorporates impedance matching circuits that provide feedback control for the electrostatic shield. By monitoring and adjusting the impedance to maintain parallel resonance conditions, the system automatically optimizes plasma characteristics for the desired etching mode, making it easier to achieve precise control over isotropic etching with varying ion energies without requiring manual tuning.
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
Enables precise control of plasma conditions for efficient removal of materials and isotropic etching, with the ability to vary ion energies from low to high, improving processing capabilities for semiconductor wafers and other substrates.
Implementation Method 1
an inductive coupling element located proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with radio frequency (RF) energy
Implementation Method 2
The electrostatic shield can have a stray capacitance to the ground reference. The tunable reactive impedance circuit can be configured to adjust a reactance range between the electrostatic shield and the ground reference between a condition of capacitive reactance and a condition of inductive reactance
Implementation Method 3
The reactance range can include an inductive reactance sufficient to achieve a parallel resonance condition with the stray capacitance between the electrostatic shield and the ground reference
Implementation Method 4
a dielectric window forming at least a portion of a wall of the plasma chamber
Data Source
AI summary
Plasma processing apparatus and associated methods are provided. In one example, a plasma processing apparatus can include a plasma chamber configured to be able to hold a plasma. The plasma processing apparatus can include a dielectric window forming at least a portion of a wall of the plasma chamber. The plasma processing apparatus can include an inductive coupling element located proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with radio frequency (RF) energy. The plasma processing apparatus can include a processing chamber having a workpiece support configured to support a workpiece. The plasma processing apparatus can include an electrostatic shield located between the inductive coupling element and the dielectric window. The electrostatic shield can be grounded via a tunable reactive impedance circuit to a ground reference.