Ion Shield Apertures for Conformal Nitridation
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Solution Overview
Problem
The non-conformal nature of plasma sheaths in typical plasma ion exposure methods prevents effective nitridation of 3D device structures, leading to issues with reactive hydrogen species and inert gas/nitrogen ions interacting with gate stack materials, which can cause device failure and non-conformal processing results.
Innovation Solution
A substrate processing method and apparatus that uses an ion shield with a bias power and apertures to control the spatial distribution of reactive and neutral species, allowing only neutral radicals to reach the substrate, thereby reducing the impact of hydrogen radicals and ions, and enhancing conformal nitridation of 3D structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If plasma ion exposure is used for nitridation, then nitrogen-containing species are introduced to the substrate, but the non-conformal nature of plasma sheath prevents conformal doping of top surface and sidewall
Solution Approach 1:
An ion shield is introduced as an intermediary component between the plasma source and substrate. The ion shield has apertures that allow neutral radicals to pass through while blocking ions. This mediator enables selective transmission of desired species (neutral nitrogen radicals) while preventing harmful species (ions) from reaching the substrate, thereby achieving conformal nitridation of 3D structures.
2Quantity of substance
If inductively coupled plasma with ammonia is used for nitridization, then nitrogen is introduced to the gate stack, but reactive hydrogen species penetrate the nitridized film and negatively interact with gate stack materials
Solution Approach 1:
The ion shield acts as a selective filter that allows neutral nitrogen radicals to pass through to nitridize the gate stack while blocking reactive hydrogen ions and molecules. This intermediary structure prevents hydrogen species from penetrating the nitridized film and interacting with gate stack materials, thereby eliminating the harmful effect while maintaining the beneficial nitridation process.
3Quantity of substance
If plasma processing is used, then nitrogen and inert gas ions are formed, but these ions contribute to non-conformal processing results
Solution Approach 1:
The ion shield with its aperture structure extracts and separates neutral radicals from the plasma mixture. By designing the aperture size and ion shield position, neutral nitrogen radicals are allowed to pass through to the substrate while ions (both nitrogen and inert gas) are excluded. This extraction of the desired neutral species from the harmful ion-containing plasma enables conformal processing results.
4Productivity
If hydrogen radicals and ions are present in the plasma, then plasma processing can be performed, but these species cause device failure
Solution Approach 1:
The ion shield serves as a protective intermediary that filters the plasma composition before it reaches the substrate. It allows the processing to continue with nitrogen-containing neutral radicals for nitridation while blocking hydrogen ions and radicals that would cause device failure. This intermediary structure maintains productivity by preserving the plasma processing capability while eliminating the reliability-threatening hydrogen species.
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 conformal nitridation of 3D structures by reducing the negative interactions of reactive species, improving processing results and preventing device failure, while allowing desirable nitrogen-containing species to effectively nitridize the substrate.
Implementation Method 1
disposing a substrate atop a substrate support disposed in a lower processing volume of a process chamber beneath an ion shield having a bias power applied thereto
Implementation Method 2
forming a plasma from the process gas within the upper processing volume
Implementation Method 3
treating the first layer with neutral radicals that pass through the ion shield
Implementation Method 4
heating the substrate to a temperature of up to about 550 degrees Celsius while treating the first layer
Data Source
AI summary
Methods and apparatus for processing a substrate are provided. In some embodiments, a method of processing a substrate having a first layer may include disposing a substrate atop a substrate support in a lower processing volume of a process chamber beneath an ion shield having a bias power applied thereto, the ion shield comprising a substantially flat member supported parallel to the substrate support, and a plurality of apertures formed through the flat member, wherein the ratio of the aperture diameter to the thickness flat member ranges from about 10:1-1:10; flowing a process gas into an upper processing volume above the ion shield; forming a plasma from the process gas within the upper processing volume; treating the first layer with neutral radicals that pass through the ion shield; and heating the substrate to a temperature of up to about 550 degrees Celsius while treating the first layer.