Upper Electrode Plasma Potential Control
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Solution Overview
Problem
Current plasma confinement methods in semiconductor wafer fabrication fail to maintain effective plasma confinement at high reactant gas flow rates, requiring substantial re-design of plasma processing systems, which is inefficient.
Innovation Solution
The use of a chamber with a lower electrode and an upper electrode, where the upper electrode is electrically isolated and controlled by a voltage source to influence the electric potential of the plasma, allowing for controlled plasma confinement through adjustment of the electric potential between the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional plasma confinement methods are used, then plasma processing can be performed, but plasma confinement is lost at high reactant gas flow rates
Solution Approach 1:
The patent changes the electric potential parameter of the upper electrode to control plasma confinement. By adjusting the DC voltage applied to the upper electrode, the plasma potential is controlled, enabling confinement at high gas flow rates without Paschen breakdown. This parameter change resolves the contradiction by allowing high productivity while maintaining reliability.
2Reliability
If the product (P*d) is minimized to maintain plasma confinement, then plasma confinement is improved, but substantial re-design of plasma processing systems is required
Solution Approach 1:
Instead of changing the physical dimensions (d) or pressure (P) which would require substantial system re-design, the patent changes the electric potential parameter of the upper electrode. This allows plasma confinement to be maintained without modifying the fundamental system design, thus improving reliability while minimizing device complexity changes.
Solution Approach 2:
The upper electrode acts as an intermediary element that controls plasma potential and confinement. By introducing this controllable intermediate component, the system can achieve better plasma confinement without requiring substantial re-design of the entire plasma processing system.
3Productivity
If high reactant gas flow rates are used, then processing efficiency is improved, but plasma confinement is lost due to Paschen breakdown
Solution Approach 1:
The patent applies preliminary anti-action by controlling the plasma potential through the upper electrode before Paschen breakdown can occur. By establishing controlled electric potential conditions, the system prevents the harmful breakdown effect from occurring, allowing high gas flow rates to be used without losing plasma confinement.
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 approach enhances plasma confinement, enabling operation at higher gas flow rates and providing flexible process parameters, including control over ion energy distribution and etch profiles, thereby improving the efficiency and versatility of plasma processing.
Implementation Method 1
The lower electrode is disposed within the chamber and is defined to transmit a radiofrequency current through the chamber
Implementation Method 2
a reactant gas is exposed to radiofrequency (RF) power to be transformed into the plasma
Implementation Method 3
The voltage source is defined to control an electric potential of the upper electrode relative to the chamber. The electric potential of the upper electrode is capable of influencing an electric potential of the plasma
Implementation Method 4
Electrons introduced into a neutral gas will gain energy if there is an electric field permeating the neutral gas
Implementation Method 5
these same electrons will also lose energy via collisions with neutral gas molecules
Implementation Method 6
The impedance control device is defined to control a radiofrequency current transmission path through the central region of the upper electrode
Data Source
AI summary
A chamber includes a lower electrode and an upper electrode. The lower electrode is defined to transmit a radiofrequency current through the chamber and to support a semiconductor wafer in exposure to a plasma within the chamber. The upper electrode is disposed above and in a spaced apart relationship with the lower electrode. The upper electrode is electrically isolated from the chamber and is defined by a central section and one or more annular sections disposed concentrically outside the central section. Adjacent sections of the upper electrode are electrically separated from each other by a dielectric material. Multiple voltage sources are respectively connected to the upper electrode sections. Each voltage source is defined to control an electric potential of the upper electrode section to which it is connected, relative to the chamber. The electric potential of each upper electrode section influences an electric potential of the plasma within the chamber.