Plasma Chamber Magnetic Coil Layout for Wafer Etch Uniformity
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in uniformly controlling plasma density distribution, particularly at the center and nodal regions, leading to non-uniform etch rates and reduced productivity in semiconductor manufacturing.
Innovation Solution
A plasma processing apparatus with a magnetic field forming unit comprising a first and second coil, covered by yokes, forms a variable divergent magnetic field to control plasma density distribution, ensuring uniformity by independently managing the magnetic flux density in the radial direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the frequency of radio frequency power is increased to generate high-density plasma, then plasma density is improved, but electric field distribution becomes non-uniform leading to non-uniform etch rate
Solution Approach 1:
The patent applies local quality by using multiple coils (first coil and second coil) with different positions and diameters to create localized magnetic field variations. The first coil generates an overall divergent magnetic field for high center plasma density, while the second coil provides local control in specific regions to manage nodal distribution and ensure uniform etch rate across the wafer surface.
Solution Approach 2:
The patent segments the magnetic field control system into multiple independent coils and yokes. The first coil with its yoke handles the overall plasma density distribution, while the second coil with its yoke independently controls local plasma density in specific regions. This segmentation allows simultaneous optimization of both high center density and uniform nodal distribution.
2Device complexity
If a single coil system is used to control plasma density, then device complexity is reduced, but the ability to independently control plasma density distribution both centrally and locally is insufficient
Solution Approach 1:
The patent divides the magnetic field control system into separate segments: a first coil system for overall plasma density control and a second coil system for local plasma density control. Each coil is paired with its own yoke structure, enabling independent adjustment of plasma density in different regions of the wafer processing area.
Solution Approach 2:
The patent extends the control system from a single-dimension approach to a multi-dimensional control architecture. The first coil operates at a higher level to control overall plasma density distribution, while the second coil operates at a local level for fine-tuned control. This hierarchical dimensional approach enables comprehensive control of plasma density both centrally and locally.
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 precise control over plasma density distribution, enhancing processing uniformity and accuracy, particularly in the middle region of a wafer, thereby improving semiconductor manufacturing efficiency.
Implementation Method 1
a magnetic field forming unit configured to form a magnetic field inside the vacuum vessel
Implementation Method 2
a plasma density distribution is made uniform by an interaction between the magnetic field and an electric field
Implementation Method 3
a radio frequency power source configured to supply radio frequency power for generating plasma
Implementation Method 4
plasma is generated by applying the radio frequency power to one electrode after introducing a desired process gas
Data Source
AI summary
In order to be able to independently control a plasma density distribution both in a distribution with high center and a nodal distribution, and perform a plasma processing on a sample with higher accuracy for processing uniformity, a plasma processing apparatus includes: a vacuum vessel in which a plasma processing is performed on a sample; a radio frequency power source configured to supply radio frequency power for generating plasma; a sample stage on which the sample is placed; and a magnetic field forming unit configured to form a magnetic field inside the vacuum vessel and disposed outside the vacuum vessel, in which the magnetic field forming unit includes: a first coil; a second coil that is disposed closer to an inner side than the first coil and has a diameter smaller than a diameter of the first coil; a first yoke that covers the first coil, and an upper side and a side surface of the vacuum vessel, and in which the first coil is disposed; and a second yoke that covers the second coil along a peripheral direction of the second coil and has an opening below the second coil.