Conductive Wafer Boat Biasing for Uniform Plasma Film Deposition
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Solution Overview
Problem
The uniformity of films formed on substrates during plasma processing is compromised due to uneven distribution of active species, particularly when multiple substrates are stacked, leading to decreased concentration in central portions.
Innovation Solution
A substrate processing apparatus with a boat made of non-metallic material, featuring a conductive surface that electrically connects to an internal conductor, ensuring uniform plasma distribution across multiple substrates through rotational symmetry and controlled DC bias application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple substrates are stacked in a multistage manner for processing, then productivity is improved, but the uniformity of film formation deteriorates due to decreased active species concentration in central portions
Solution Approach 1:
The boat is rotated during plasma processing to dynamically change the position of substrates relative to the plasma source. This rotation ensures that all substrates, including those in central positions, receive uniform plasma exposure and active species distribution, thereby maintaining film uniformity while processing multiple substrates simultaneously
Solution Approach 2:
A conductor is introduced as an intermediary element connected to the boat. This conductor applies a negative bias voltage to attract positive ions and enhance plasma interaction, ensuring uniform active species distribution across all substrates including those in central positions, thus maintaining film uniformity while enabling multi-substrate processing
2Device complexity
If plasma is supplied through edges of substrates, then device complexity is reduced, but active species distribution becomes uneven causing film uniformity deterioration
Solution Approach 1:
By rotating the boat during plasma processing, the system dynamically redistributes plasma exposure across all substrate surfaces. This simple mechanical motion transforms edge-supplied plasma into uniform full-surface coverage, achieving even active species distribution without complicating the plasma supply structure
Solution Approach 2:
The application of negative bias voltage through the conductor changes the electrical parameters of the plasma-substrate interaction. This parameter change attracts positive ions toward the substrates and enhances plasma penetration, converting edge-supplied plasma into uniformly distributed active species across the entire substrate surface
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
Enhances film uniformity on substrate surfaces by promoting even plasma interaction, reducing sheath formation, and facilitating uniform film deposition despite substrate stacking.
Implementation Method 1
a plasma generating structure configured to supply a plasma into the process chamber
Implementation Method 2
the boat is configured to electrically connect the internal conductor and the plurality of substrates
Data Source
AI summary
According to one aspect of the technique of the present disclosure, there is provided a substrate processing apparatus including: a process chamber; a process gas supplier through which a process gas is supplied into the process chamber; an exhauster through which an inner atmosphere of the process chamber is exhausted; a plasma generating structure configured to supply a plasma into the process chamber; a boat configured to accommodate a plurality of substrates in the process chamber; a rotary shaft configured to rotatably support the boat; and an internal conductor provided inside the rotary shaft and electrically connected to the boat; wherein the boat is made of a non-metallic material, at least a part of a surface of the boat is conductive, and the boat is configured to electrically connect the internal conductor and the plurality of substrates.