Layered Shielding Plate for Plasma Chamber Magnetic Field Control
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Solution Overview
Problem
Existing substrate processing apparatuses face challenges in simultaneously shielding external static magnetic fields and low-frequency electromagnetic fields, which can affect plasma characteristics and deposition uniformity, as conventional non-magnetic conductors fail to block these fields effectively and ferromagnetic materials can be heated by electromagnetic waves, leading to performance degradation.
Innovation Solution
A capacitively coupled plasma substrate processing apparatus with a shielding plate composed of a bottom non-magnetic conductive plate, a middle ferromagnetic plate, and a top non-magnetic conductive plate, where the ferromagnetic plate is used to shield static magnetic fields and low-frequency electromagnetic waves without being inductively heated, while the conductive plates absorb RF electromagnetic waves, ensuring efficient shielding and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a ferromagnetic material is used to shield static magnetic fields, then magnetic shielding effectiveness is improved, but the material can be heated by electromagnetic waves leading to performance degradation
Solution Approach 1:
The shielding plate is divided into multiple functional layers: a non-magnetic conductive plate for RF shielding, a ferromagnetic plate for static magnetic field shielding, and another non-magnetic conductive plate for additional RF shielding. This segmentation allows each layer to perform its specific function without interfering with others, preventing the ferromagnetic material from being heated by RF electromagnetic waves.
Solution Approach 2:
The shielding plate uses a composite structure combining non-magnetic conductive materials (such as aluminum or copper) with ferromagnetic materials (such as permalloy or mu-metal). This composite design enables simultaneous shielding of both RF electromagnetic waves and static magnetic fields while preventing thermal degradation of the ferromagnetic layer.
2Object-affected harmful factors
If a single-layer ferromagnetic shielding plate is used, then static magnetic field shielding is improved, but RF electromagnetic waves cause inductive heating and performance degradation
Solution Approach 1:
The shielding plate is divided into multiple functional layers: a non-magnetic conductive plate for RF shielding, a ferromagnetic plate for static magnetic field shielding, and another non-magnetic conductive plate for additional RF shielding. This segmentation allows each layer to perform its specific function without interfering with others.
Solution Approach 2:
The non-magnetic conductive plates act as intermediary layers that block RF electromagnetic waves from reaching the ferromagnetic plate, preventing inductive heating. These intermediary layers protect the ferromagnetic material while allowing it to perform its static magnetic field shielding function.
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 solution effectively shields both RF and low-frequency electromagnetic waves and static magnetic fields, improving deposition uniformity and process stability by preventing performance degradation due to heating, thus enhancing the uniformity of plasma processing.
Implementation Method 1
a bottom surface of the electromagnetic shielding box includes a center shielding plate including a ferromagnetic material to provide effective magnetic shielding
Implementation Method 2
a side all and a top surface which are formed of a non-magnetic metal having a high electric conductivity for efficient RF shielding
Implementation Method 3
The center shielding plate disposed at the bottom surface of the electromagnetic shielding box may have a remanent magnetization and change characteristics of its underlying plasma to improve a deposition uniformity
Data Source
AI summary
A capacitively coupled plasma substrate processing apparatus includes: a process chamber which is exhausted to vacuum and provides a sealed internal space; a gas inflow pipe which is connected to the process chamber to provide a process gas into the process chamber; a gas distribution unit which is connected to the gas inflow pipe to inject the process gas flowing into the gas inflow pipe in the internal space; an impedance matching network which is disposed outside the process chamber and transfers an RF power of an RF power supply to the gas distribution unit; an RF connection line which connects an output of the impedance matching network to the gas inflow pipe or the gas distribution unit; and a shielding plate which is configured such that at least one of the RF connection line and the gas inflow pipe penetrates the shielding plate and includes a ferromagnetic material.