Selective Nitride Etching Using Remote Plasma Effluents
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Solution Overview
Problem
Conventional etching methods face challenges in achieving uniform top-to-bottom etching of nitride materials in high-aspect-ratio trenches and struggle to maintain selectivity between nitride and oxide materials, often resulting in residual byproducts and non-tunable recess profiles.
Innovation Solution
A dry etching process using a fluorine-containing precursor and a hydrogen-containing precursor, where the precursors are flowed into a remote plasma region to generate plasma effluents, which are then introduced into a semiconductor processing chamber, allowing for selective removal of nitride relative to oxide with tunable recess profiles and high selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wet HF etch is used to remove silicon oxide, then oxide removal efficiency is improved, but penetration into constrained trenches is poor and material deformation occurs
Solution Approach 1:
The patent replaces wet chemical etching with a dry plasma-based etching process. The plasma etching system uses reactive species and ion bombardment to remove materials, substituting the wet chemical mechanism with a physical-chemical plasma process that provides better trench penetration and control over material removal, eliminating deformation issues associated with wet etching
Solution Approach 2:
The patent employs parameter changes by controlling plasma conditions (power, pressure, gas composition, temperature) to achieve selective etching. By adjusting these parameters, the process achieves high oxide removal rates while maintaining trench penetration capability and preventing material deformation, resolving the contradiction between productivity and manufacturing precision
2Manufacturing precision
If local plasma is used to etch constrained trenches, then trench penetration is improved, but substrate damage occurs due to electric arcs
Solution Approach 1:
The patent introduces a remote plasma source as an intermediary between the plasma generation region and the substrate. The plasma is generated in a remote region and then transported to the substrate area, allowing trench penetration without direct arc discharge on the substrate. This intermediary approach maintains the beneficial penetration effects while eliminating the harmful substrate damage from electric arcs
Solution Approach 2:
The patent segments the plasma process into separate regions: a plasma generation region where plasma is created, and a processing region where the plasma interacts with the substrate. This spatial segmentation allows the plasma to be generated under conditions optimal for trench penetration while preventing direct arc formation on the substrate, thus resolving the contradiction between penetration capability and substrate damage
3Productivity
If conventional etching methods are used for nitride removal, then etching speed is improved, but selectivity between nitride and oxide deteriorates
Solution Approach 1:
The patent uses parameter changes by controlling plasma power, pressure, and gas composition to achieve selective nitride etching. By optimizing these parameters, the process achieves high etching speeds for nitride while maintaining selectivity against oxide, resolving the contradiction between productivity and manufacturing precision. The selective removal of nitride with high speed and high selectivity is achieved through precise parameter control
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 process achieves uniform etching across high-aspect-ratio features, reduces residual byproducts, and allows for tuning of the recess profile, achieving selectivity ratios greater than 500:1 between nitride and oxide, surpassing conventional methods.
Implementation Method 1
forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor
Implementation Method 2
selectively removing at least a portion of the exposed silicon nitride relative to the exposed oxide
Data Source
AI summary
Exemplary methods for removing nitride may include flowing a fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. The methods may further include forming a plasma within the remote plasma region to generate plasma effluents of the fluorine-containing precursor and flowing the plasma effluents into a processing region of the semiconductor processing chamber housing a substrate. The substrate may include a high-aspect-ratio feature. The substrate may further include a region of exposed nitride and a region of exposed oxide. The methods may further include providing a hydrogen-containing precursor to the processing region to produce an etchant. At least a portion of the exposed nitride may be removed with the etchant.