Seam-Free Silicon Gap Fill Using Hydrogen Plasma Sidewall Etching
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Solution Overview
Problem
Conventional semiconductor processing technologies face challenges in filling narrow features with high aspect ratios due to seam or void formation, often requiring multiple etch cycles and halogen etchants, which can leave residues and result in poor material quality.
Innovation Solution
The method involves forming plasma effluents of silicon-containing and hydrogen-containing precursors to deposit and etch silicon-containing materials, followed by conversion to silicon-and-nitrogen-containing or silicon-and-oxygen-containing materials, using a halogen-free etching process to control sidewall coverage and densify the material, reducing hydrogen content and preventing residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods are used to fill narrow features, then material can be deposited, but seams and voids form within the feature due to pinching off between sidewalls
Solution Approach 1:
The deposition process is divided into multiple discrete deposition steps separated by etch steps. Each deposition step deposits a thin layer of material, and the subsequent etch step removes material from sidewalls before the next deposition. This segmentation prevents continuous deposition from pinching off the feature and forming seams or voids, allowing complete filling while maintaining feature integrity.
2Reliability
If multiple etch cycles are used to prevent seam formation, then seam formation is reduced, but halogen residues are left and material quality deteriorates
Solution Approach 1:
The harmful halogen etchants are extracted and replaced with a hydrogen-based plasma etching process. The hydrogen plasma selectively removes deposited material from sidewalls without introducing halogen residues. This extraction of the harmful element (halogen) while maintaining the necessary etching function eliminates residue contamination and preserves material quality.
Solution Approach 2:
Hydrogen, which can be harmful when incorporated into the deposited material causing defects, is converted into a beneficial etching agent. The hydrogen plasma etches sidewalls selectively while the process parameters are controlled to prevent excessive hydrogen incorporation into the fill material. Thus, hydrogen serves dual purposes: as a clean etching agent and as a controlled component of the final material.
3Ease of manufacture
If hydrogen-containing precursors are used for deposition, then material can be formed, but hydrogen incorporation reduces material quality and requires densification
Solution Approach 1:
A densification step is performed as a preliminary action before final deposition completion. This densification process, using hydrogen plasma, removes excess hydrogen from the deposited material and improves material density and quality. By performing this preliminary densification, the subsequent deposition steps can proceed with hydrogen-containing precursors while maintaining high material quality throughout the fill process.
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 limits seam formation, enhances material quality by reducing hydrogen content, and improves resistance to subsequent etching, resulting in high-quality silicon-containing materials with desirable mechanical and electrical characteristics.
Implementation Method 1
forming plasma effluents of the silicon-containing precursor... depositing a silicon-containing material on the substrate
Implementation Method 2
forming plasma effluents of the hydrogen-containing precursor... etching the silicon-containing material from a sidewall of the feature with the plasma effluents
Implementation Method 3
forming plasma effluents of the conversion precursor... converting the remaining silicon-containing material to a silicon-and-nitrogen-containing material or a silicon-and-oxygen-containing material
Data Source
AI summary
Exemplary processing methods may include providing a silicon-containing precursor to a processing region of a semiconductor processing chamber. A substrate may be housed in the processing region. The substrate may define a feature. The methods may include forming plasma effluents of the silicon-containing precursor and depositing a silicon-containing material on the substrate. The methods may include providing a hydrogen-containing precursor to the processing region, forming plasma effluents of the hydrogen-containing precursor, and etching the silicon-containing material from a sidewall of the feature.