Plasma Nozzle Shroud for Etch Damage Control
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Solution Overview
Problem
Current plasma etching processes in semiconductor fabrication face challenges in controlling etch damage and achieving uniformity across the wafer surface due to uncontrolled plasma flows, leading to inefficiencies in localized or partial plasma etching.
Innovation Solution
A plasma processing apparatus and method that utilize a nozzle to direct plasma as a stream onto a wafer, with a gas annulus or shroud surrounding the nozzle, and a vacuum system to maintain different pressures within the chamber and exhaust areas, allowing for controlled plasma flow and removal of unreacted plasma, thereby reducing etch damage and enhancing surface uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If localized or partial plasma etch is used to remove material in a specific region, then etching precision in targeted areas is improved, but uncontrolled plasma flows cause etch damage to surrounding regions
Solution Approach 1:
A gas shroud surrounding the nozzle acts as an intermediary structure to control plasma flow. The shroud confines the plasma stream to the intended target area while preventing uncontrolled expansion into surrounding regions, thereby reducing etch damage to adjacent areas while maintaining etching precision in the targeted region.
Solution Approach 2:
The gas shroud creates localized control zones around the plasma stream. By introducing gas flow through the shroud structure, the plasma is contained and directed precisely where needed, providing different flow control characteristics in different spatial zones - confined plasma at the target area and controlled exhaust in surrounding regions.
2Productivity
If plasma processes are used for thinning and planarization, then material removal capability is improved, but control over localized thinning is insufficient
Solution Approach 1:
The gas shroud structure segments the plasma flow into a directed stream, separating the high-energy plasma core from the surrounding chamber environment. This segmentation allows the plasma to maintain its material removal capability while being spatially confined to achieve localized thinning with precise control over the affected area.
3Speed
If conventional plasma etching is used, then etching speed is maintained, but uniformity across the wafer surface deteriorates
Solution Approach 1:
The gas shroud serves as a mediator that maintains etching speed by preserving plasma energy while improving uniformity through controlled distribution. The shroud structure directs the plasma stream systematically across the wafer surface, ensuring consistent exposure and etching rates across different regions.
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 solution enables high-resolution etching with reduced etch damage to surrounding regions and improved uniformity across the wafer surface by controlling plasma flow and immediately removing unreacted plasma, resulting in more precise and effective plasma processing.
Implementation Method 1
maintaining a first pressure in the gas exhaust using a first vacuum pump; and maintaining a second pressure in the processing chamber using a second vacuum pump, the first pressure and the second pressure being different
Data Source
AI summary
An embodiment plasma processing apparatus includes a plasma generation source, a nozzle in a plasma chamber, the nozzle being able to direct plasma from the plasma generation source to a wafer that is to be processed, the plasma having the form of a plasma stream at an exit of the nozzle, an outer annulus disposed in the plasma chamber and over the wafer, the outer annulus surrounding the nozzle, a gas exhaust disposed between inner sidewalls of the outer annulus and outer sidewalls of the nozzle, and a first vacuum pump connected to the gas exhaust between the inner sidewalls of the outer annulus and the outer sidewalls of the nozzle.