Electrostatic Shield Layout for Plasma Vessel Sputter Suppression
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Solution Overview
Problem
The generation of sputtering on the inner peripheral surface of a process vessel during plasma excitation of a process gas leads to contamination of the substrate processing, affecting the modification process in semiconductor device manufacturing.
Innovation Solution
A substrate processing apparatus with a coil wound around the outer peripheral surface of the process vessel and an electrostatic shield with openings arranged vertically between the coil and the vessel, which suppresses sputtering by minimizing electric field interaction with the vessel walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high frequency power is supplied to the coil to excite plasma in the process vessel, then the modification process can be performed, but sputtering occurs on the inner peripheral surface of the process vessel causing contamination
Solution Approach 1:
An electrostatic shield is introduced as an intermediary component between the coil and the process vessel. The shield includes a grounded cylindrical body with radial openings that intercept and redirect electric field lines, preventing direct interaction between the coil's electric field and the process vessel wall. This mediator structure reduces ion acceleration toward the vessel surface while maintaining plasma generation efficiency.
Solution Approach 2:
The electrostatic shield is strategically positioned only in regions where electric field concentration causes excessive ion acceleration and sputtering. The radial openings are arranged to provide localized shielding at critical zones while allowing plasma to penetrate and maintain processing functionality in other areas, creating a non-uniform protection strategy.
2Use of energy by moving object
If the coil is placed close to the process vessel to efficiently generate plasma, then energy efficiency is improved, but electric field interaction with the vessel wall increases causing sputtering
Solution Approach 1:
The electrostatic shield serves as a mediator that allows the coil to operate at optimal coupling distance for energy efficiency while preventing harmful electric field interactions. The shield's conductive structure with radial openings redirects electric field lines away from the process vessel wall, decoupling the energy transfer function from the harmful field interaction.
Solution Approach 2:
The electrostatic shield modifies the electric field distribution parameters in the region between the coil and process vessel. By introducing a grounded conductive structure with specific geometry (radial openings), the field line density and direction are changed, reducing the component of electric field that accelerates ions toward the vessel surface while maintaining overall plasma generation efficiency.
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 effectively reduces sputtering, maintaining the integrity of the process vessel and enhancing the quality of substrate processing by preventing material release into the film formed on the substrate.
Implementation Method 1
a high frequency power is supplied to the coil
Implementation Method 2
an electrostatic shield disposed between the outer peripheral surface of the process vessel and the coil
Implementation Method 3
reactive species such as radicals and ions and electrons may be generated in a process vessel when the substrate is processed
Implementation Method 4
Due to an electric field formed by an electrode to which a high frequency power is applied, the ions generated in the process vessel may be accelerated
Implementation Method 5
the ions generated in the process vessel may be accelerated and may collide with an inner peripheral surface of the process vessel to cause sputtering
Data Source
AI summary
Described herein is a technique capable of suppressing sputtering on an inner peripheral surface of a process vessel when a process gas is plasma-excited in the process vessel. According to one aspect thereof, a substrate processing apparatus includes: a process vessel accommodating a process chamber where a process gas is excited into plasma; a gas supplier supplying the process gas into the process chamber; a coil wound around an outer peripheral surface of the process vessel and spaced apart therefrom, wherein a high frequency power is supplied to the coil; and an electrostatic shield disposed between the outer peripheral surface and the coil, wherein the electrostatic shield includes: a partition extending in a circumferential direction to partition between a part of the coil and the outer peripheral surface; and an opening extending in the circumferential direction and opened between another part of the coil and the outer peripheral surface.