Tunable Plasma Chamber Shielding for Ion Energy Control
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Solution Overview
Problem
Existing plasma processing tools face challenges in achieving high plasma uniformity, controlling plasma density and ion energy, sustaining plasma under varying conditions, and efficiently removing difficult materials like photoresists and hard surface layers, while also providing anisotropic and isotropic etching capabilities.
Innovation Solution
A plasma processing apparatus with a dielectric window, inductive coupling element, and an electrostatic shield connected via tunable reactive impedance circuits to control RF voltage, allowing for adjustable plasma potential and ion bombardment energy, enabling flexible etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing tools are used, then basic plasma generation is achieved, but plasma uniformity and control over plasma density and ion energy are insufficient
Solution Approach 1:
The plasma chamber is divided into two distinct chambers: an inductive plasma generation chamber and a processing chamber. This segmentation allows independent optimization of plasma generation (uniformity) and processing (control capability), resolving the contradiction between achieving uniform plasma and maintaining versatile control.
Solution Approach 2:
A gas distribution system acts as an intermediary between the plasma generation chamber and processing chamber. This intermediary controls the flow of reactive species and neutral gas, enabling precise control over plasma density and ion energy while maintaining plasma uniformity through regulated gas distribution.
2Productivity
If high plasma density is achieved, then processing efficiency improves, but ion energy control and plasma uniformity deteriorate
Solution Approach 1:
By separating plasma generation from processing functions into different chambers, the system can maintain high plasma density in the generation chamber for efficiency while independently controlling ion energy in the processing chamber, resolving the trade-off between productivity and precision.
Solution Approach 2:
The gas distribution system uses pneumatic control to regulate gas flow rates and pressure, enabling independent control of plasma parameters (density and ion energy) to simultaneously achieve high processing efficiency and precise ion energy control.
3Adaptability or versatility
If plasma is sustained under varying conditions, then process flexibility improves, but plasma stability and uniformity worsen
Solution Approach 1:
The dual-chamber design separates the plasma generation environment from the processing environment, allowing each chamber to be optimized for its specific function. The plasma generation chamber maintains stable plasma under varying conditions while the processing chamber provides flexibility for different processing requirements.
Solution Approach 2:
The gas distribution system serves as a buffer and mediator that decouples the plasma generation chamber from processing chamber variations. It absorbs fluctuations and maintains plasma stability while allowing process flexibility through adjustable gas flow and composition control.
4Productivity
If difficult materials like photoresists and hard surface layers are removed, then productivity improves, but plasma uniformity and ion energy control deteriorate
Solution Approach 1:
The segmented chamber design allows the plasma generation chamber to provide high-density plasma for efficient material removal while the processing chamber maintains controlled ion energy and uniform distribution, enabling both high productivity and etch uniformity simultaneously.
Solution Approach 2:
The system dynamically adjusts plasma parameters (density, temperature, composition) and ion energy independently in each chamber. This parameter control enables efficient removal of difficult materials while maintaining uniform etching through precise regulation of plasma and ion characteristics.
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 apparatus achieves wide-ranging control over plasma potential and ion energy, facilitating efficient removal of challenging materials and precise etching processes, including anisotropic and isotropic etching with controlled ion bombardment.
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 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 at a frequency of RF energy supplied to the inductive coupling element
Implementation Method 3
The electrostatic shield can have a stray capacitance to the ground reference
Data Source
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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.