Buffer Chamber Electrodes for Stable Plasma Generation
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Solution Overview
Problem
Existing substrate processing apparatuses face challenges in stabilizing plasma generation and reducing damage to reaction tubes and electrodes, particularly when high frequency power is applied, leading to instability and shortened equipment lifespan.
Innovation Solution
A substrate processing apparatus is designed with a buffer chamber containing parallel discharge electrodes covered by insulator sheath tubes and equipped with a metal cap at the electrode ends to prevent exposure to gas and plasma, using refractory metals for the electrodes to prevent deterioration and electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high frequency power is increased to stabilize plasma generation, then plasma stability is improved, but damage to reaction tube and electrode increases
Solution Approach 1:
A buffer chamber is introduced as an intermediary space between the plasma generation region and the reaction tube. The buffer chamber allows plasma to be generated at high frequency power while preventing direct contact between the plasma and the reaction tube, thus stabilizing plasma generation without increasing damage to the reaction tube.
Solution Approach 2:
The processing space is segmented into a buffer chamber and a reaction tube chamber. The discharge electrodes are positioned in the buffer chamber, separating the plasma generation function from the substrate processing function. This segmentation allows high frequency power to be applied for stable plasma generation while the reaction tube remains protected from direct plasma exposure.
2Manufacturing precision
If high frequency power is increased to improve film-forming conditions, then film quality is improved, but electrode deterioration accelerates
Solution Approach 1:
The buffer chamber serves as a mediator that enables high frequency power application for improved film quality while protecting the electrodes from direct plasma damage. The buffer gas in this chamber absorbs the plasma energy, allowing high power operation without accelerating electrode deterioration.
Solution Approach 2:
The buffer chamber provides beforehand cushioning for the electrodes by positioning them in a region where plasma can be generated at high frequency power without directly contacting the electrodes. This prior protection allows sustained high power operation that improves film quality while extending electrode lifespan.
3Productivity
If plasma power is increased to enhance chemical reaction, then film deposition rate is improved, but reaction tube damage increases
Solution Approach 1:
The buffer chamber acts as an intermediary that enables high plasma power operation for improved deposition rate while preventing direct plasma contact with the reaction tube. The buffer gas absorbs plasma energy, allowing high productivity operation without increasing reaction tube damage.
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
This configuration allows for stable plasma generation while reducing damage to the reaction tube and electrodes, extending their lifespan and improving processing efficiency.
Implementation Method 1
a film-forming process of depositing a predetermined film on a substrate may be performed by using a CVD (Chemical Vapor Deposition) method or an ALD (Atomic Layer Deposition) method using plasma
Implementation Method 2
The CVD method refers to a method of depositing a film, whose constituent elements are those contained in molecules of a source gas, on a substrate to be processed using a chemical reaction such as a gas phase reaction of a gaseous source and a reaction on a surface of the substrate
Implementation Method 3
a pair of sheath tubes, each of which is made of an insulator, configured to cover the pair of the discharge electrodes, respectively, to prevent the pair of the discharge electrodes from being exposed to the gas
Implementation Method 4
a metal cap, whose outer diameter is substantially equal to an outer diameter of each of the discharge electrodes and whose front end is rounded, is provided at one end of one or each of the discharge electrodes other than the other end of the one or each of the discharge electrodes supplied with electric power
Data Source
AI summary
Described herein is a technique capable of reducing a damage to a reaction tube and an electrode when processing a substrate using plasma as well as generating the plasma stably. According to one aspect thereof, there is provided a substrate processing apparatus including: a process chamber; a buffer chamber where a gas is circulated before being supplied to a substrate; a pair of discharge electrodes extending parallel to each other in the buffer chamber; and a pair of sheath tubes configured to cover the pair of the discharge electrodes to prevent them from being exposed to the gas. A metal cap, whose outer diameter is equal to that of the discharge electrode and whose front end is rounded, is provided at one end of one or each of the discharge electrodes other than the other end of the one or each of the discharge electrodes supplied with electric power.