Differentially Pumped Reactive Gas Injector for Ion Etching
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Solution Overview
Problem
In semiconductor fabrication, ion beam etching processes face challenges in achieving high throughput due to the low pressure required in reactive ion beam etching, which limits the rate at which reactants can be delivered to the substrate, leading to inefficient material removal and prolonged processing times.
Innovation Solution
The use of an injection head that delivers reactants at a local high pressure while maintaining a lower pressure in the substrate processing area by employing a vacuum to remove excess reactants, allowing for both efficient reactant delivery and ion beam etching in the same chamber without extinguishing the plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low pressure is maintained in the substrate processing area to enable ion beam etching, then ion beam processing can be performed, but the rate of reactant delivery to the substrate is limited
Solution Approach 1:
The reaction chamber is segmented into a global low-pressure substrate processing region and a localized high-pressure reactant delivery region. The injection head creates a confined high-pressure zone at the substrate surface while the rest of the chamber maintains low pressure for ion beam processing. This spatial segmentation allows simultaneous optimization of both ion beam etching and reactant delivery rates.
Solution Approach 2:
The injection head delivers reactants at locally high pressure (e.g., 1-100 Torr) directly at the substrate surface, while the global chamber pressure remains low (e.g., 10^-3 to 10^-6 Torr). This local quality approach enables high reactant concentration where needed without compromising the overall low-pressure environment required for ion beam processing.
2Productivity
If high pressure is used for reactant delivery to improve material removal rate, then productivity increases, but ion beam processing becomes difficult due to excessive reactant collisions with ions
Solution Approach 1:
The injection head extracts and confines the high-pressure reactant delivery to a localized region immediately adjacent to the substrate surface. By taking out the high-pressure zone from the global chamber environment and confining it to a small volume near the substrate, the system achieves high material removal rates without allowing excessive reactant scattering into the ion beam path.
Solution Approach 2:
The system transitions from a uniform pressure environment to a spatially differentiated pressure field with vertical and radial gradients. The injection head creates a pressure gradient where high pressure exists in the vertical direction at the substrate surface for reactant delivery, while the horizontal/chamber environment maintains low pressure for ion beam processing.
3Productivity
If reactants are delivered at high pressure to increase etching efficiency, then material removal improves, but processing time increases due to prolonged reactant presence in the chamber
Solution Approach 1:
The injection head delivers reactants in a concentrated, rapid pulse directly to the substrate surface and quickly removes excess reactants via the vacuum system. This rushing through approach minimizes the residence time of reactants in the chamber, enabling high etching efficiency without prolonged processing times. The localized high-pressure zone allows rapid reactant-substrate interaction followed by quick evacuation.
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 enables faster material removal with improved throughput by maintaining a high pressure for reactant delivery while keeping the overall substrate processing area at a low pressure, minimizing reactant collisions with ions and enhancing the uniformity of ion and reactant flux across the substrate.
Implementation Method 1
The low pressure may be maintained by applying vacuum pressure in areas surrounding or abutting the local high pressure reactant delivery area of the injection head
Implementation Method 2
The ion source typically includes a plasma generator for generating a plasma
Implementation Method 3
an ion source configured to deliver ions toward the substrate support
Implementation Method 4
an injection head for providing reactants to a surface of the substrate when the substrate is positioned on the substrate support, the injection head including: a substrate-facing region including (i) a reactant outlet region of a reactant delivery conduit
Data Source
AI summary
One process used to remove material from a surface is ion etching. In certain cases, ion etching involves delivery of both ions and a reactive gas to a substrate. The disclosed embodiments permit local high pressure delivery of reactive gas to a substrate while maintaining a much lower pressure on portions of the substrate that are outside of the local high pressure delivery area. In many cases, the low pressure is achieved by providing an injection head that confines the high pressure reactant delivery to a small area and vacuums away excess reactants and byproducts as they leave this small area and before they enter the larger substrate processing region. The disclosed injection head may be used to increase throughput while minimizing deleterious collisions between ions and other species present in the substrate processing region. The disclosed injection head may also be used in other types of semiconductor wafer processing.