Tunable Plasma Potential Chamber for Uniform Ion Energy Control
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Solution Overview
Problem
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 hardening surface layers, while also providing isotropic and anisotropic etching capabilities.
Innovation Solution
A plasma processing apparatus with an inductive coupling element, a dielectric window, and an electrostatic shield connected via tunable reactive impedance circuits to control RF voltage and plasma potential, allowing for adjustable reactance ranges to manage plasma characteristics and ion bombardment energies.
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 precision are insufficient
Solution Approach 1:
The patent implements dynamic control of plasma characteristics by independently adjusting plasma density and ion energy through separate RF power sources. The plasma density is controlled by the inductive coupling element while ion energy is controlled by the electrostatic shield, allowing real-time optimization for different processing requirements and achieving high plasma uniformity across the substrate.
Solution Approach 2:
The system changes multiple plasma parameters simultaneously and independently - plasma density, ion energy, and plasma potential - through separate control circuits. This multi-parameter control enables precise adjustment of etching characteristics for both isotropic and anisotropic modes, resolving the contradiction between precision and complexity by providing systematic control mechanisms.
2Productivity
If high plasma density is achieved, then processing speed increases, but ion energy control and plasma uniformity deteriorate
Solution Approach 1:
The patent segments the plasma control functions into independent modules: the inductive coupling element controls plasma density for processing speed, while the electrostatic shield independently controls ion energy for precision. This functional segmentation allows simultaneous optimization of both productivity and manufacturing precision without compromise.
Solution Approach 2:
The electrostatic shield acts as an intermediary element that decouples the control of ion energy from plasma density. By placing the shield between the plasma source and the substrate, it enables independent modulation of ion energy while maintaining high plasma density, thus achieving both high productivity and precise ion energy control.
3Productivity
If isotropic etching is performed, then material removal efficiency improves, but anisotropic etching capability is lost
Solution Approach 1:
The system dynamically switches between isotropic and anisotropic etching modes by adjusting the ratio of plasma density to ion energy through independent RF power control. For isotropic etching, high plasma density with moderate ion energy is used for efficient material removal. For anisotropic etching, the system increases ion energy while maintaining plasma density, providing directional etching. This dynamic adaptability resolves the contradiction between efficiency and versatility.
4Manufacturing precision
If plasma potential is increased, then ion energy and etching anisotropy improve, but plasma uniformity and control precision deteriorate
Solution Approach 1:
The patent changes plasma potential as a controlled parameter through the electrostatic shield while maintaining plasma density stability through the inductive coupling element. This separate parameter control allows increasing plasma potential for better etching anisotropy without compromising plasma uniformity, as the two parameters are independently adjustable through dedicated control circuits.
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 potential and ion energy for isotropic and anisotropic etching, effectively removing challenging materials and ensuring uniform processing across diverse conditions.
Implementation Method 1
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 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
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.