PVD Chamber Plate Venting for Stable Plasma Ignition
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Solution Overview
Problem
In semiconductor fabrication, maintaining suitable chamber pressure for plasma ignition in physical vapor deposition (PVD) processes is challenging due to gas leakage through multiple nut plates, leading to unstable plasma conditions and potential ignition failure.
Innovation Solution
A PVD apparatus with a chamber plate featuring three tunable nut plates and corresponding cavities, which limits gas leakage and allows for precise control of chamber pressure by adjusting the size of these cavities to maintain optimal conditions for plasma ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple nut plates are used in the chamber plate, then the structural integrity and sealing are improved, but gas leakage increases leading to pressure control issues
Solution Approach 1:
The chamber plate is divided into multiple sealed compartments, each with its own nut plate and independent pressure control. This segmentation allows each compartment to maintain its own pressure independently, preventing gas leakage from affecting the entire chamber while still providing structural integrity through multiple connection points.
Solution Approach 2:
Sealing elements such as gaskets or O-rings are introduced as intermediaries between the nut plates and the chamber plate body. These sealing intermediaries prevent direct gas leakage paths while allowing the nut plates to maintain structural connections, thus resolving the contradiction between structural integrity and pressure control.
2Stress or pressure
If the chamber pressure is reduced for vacuum operation, then the PVD process is enabled, but plasma ignition becomes difficult due to insufficient gas density
Solution Approach 1:
Gas is introduced into the chamber before the vacuum pump reaches full operation, creating a preliminary gas atmosphere that enables plasma ignition. The system performs preliminary gas filling at controlled pressure levels before transitioning to full vacuum operation, ensuring that plasma ignition conditions are met before pressure reduction begins.
Solution Approach 2:
The system employs periodic pulsing of gas flow during the vacuum cycle, creating oscillating pressure conditions that facilitate plasma ignition intermittently. This periodic gas introduction maintains sufficient gas density during critical ignition phases while allowing vacuum operation to proceed overall.
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 design ensures stable and sustainable plasma ignition, improving the deposition process by maintaining higher target pressures and preventing pressure drops, thereby enhancing film quality and process reliability.
Implementation Method 1
maintain suitable chamber pressure for plasma ignition
Implementation Method 2
limits gas leakage through multiple nut plates
Implementation Method 3
A sputtering process may occur by bombarding a sputtering target with highly energized ions (as in a plasma) to free particles from the sputtering target. The free particles then attach themselves to the substrate, thereby forming a thin film.
Implementation Method 4
highly energized ions (as in a plasma)
Implementation Method 5
A commonly used semiconductor fabrication process is physical vapor deposition (PVD), during which a thin film is formed on a substrate through a sputtering process.
Data Source
AI summary
A chamber for a physical vapor deposition (PVD) apparatus includes a collimator configured to narrow filter sputtered particles into a beam, an electrostatic chuck configured to support a substrate in the chamber, a shield and a chamber plate. The chamber plate includes a nut plate portion having a plurality of nut plates and a plurality of cavities in the chamber plate that are configured to allow gas to ingress and egress, wherein the cavities and nut plates are provided in equal numbers. The chamber is configured to operate at a target pressure, and the number of nut plates and corresponding number of cavities are determined based on the target pressure.