Selective Silicon Oxide Gap Fill for Void-Free Narrow Features
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Solution Overview
Problem
As semiconductor feature sizes shrink, conventional gap fill processes face challenges in filling features with high aspect ratios and narrow widths, leading to pinching-off and void formation due to deposition on sidewalls, which affects device performance and thermal budgets.
Innovation Solution
A method involving sequential deposition, oxidation, and etching cycles using silicon-containing, oxygen-containing, and fluorine-containing precursors in a semiconductor processing chamber, where plasma effluents are formed at specific power levels and bias powers to selectively deposit and etch silicon-and-oxygen-containing materials, controlling sidewall coverage and reducing thermal budgets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition is used to fill features, then material is deposited on sidewalls and top surface, but this causes pinching-off and void formation in high aspect ratio features
Solution Approach 1:
The deposition process is segmented into multiple cycles alternating between deposition and etching steps. Each cycle deposits material partially into the feature, then the etching step removes material from sidewalls that would otherwise cause pinching-off. This segmentation allows continuous filling without void formation while maintaining feature integrity.
Solution Approach 2:
The process employs periodic alternation between deposition and etching operations. During deposition phases, material is deposited at controlled rates; during etching phases, sidewall material is selectively removed. This periodic action prevents accumulation of sidewall material that would lead to pinching-off, enabling complete feature filling.
2Quantity of substance
If deposition occurs at top and sidewalls of features, then material forms on all surfaces, but continued deposition pinches off the feature and produces voids
Solution Approach 1:
The etching step introduces local selectivity by removing material preferentially from sidewalls while preserving material at the feature bottom. This local quality control ensures that deposition continues uniformly into the feature without sidewall material accumulation, maintaining fill uniformity despite continued material deposition.
3Manufacturing precision
If high temperature processing is used for oxidation, then silicon-containing material is converted to silicon oxide, but this increases thermal budget and processing temperature
Solution Approach 1:
The oxidation process parameters are changed by introducing oxygen-containing precursors during plasma-enhanced deposition cycles rather than using conventional high-temperature thermal oxidation. This parameter change enables silicon-to-silicon-oxide conversion at reduced temperatures, lowering the thermal budget while maintaining conversion efficiency.
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 effectively limits seam or void formation in small features, reduces processing temperature, and enables full filling of features without pinching-off, improving device performance and thermal management.
Implementation Method 1
forming plasma effluents of the silicon-containing precursor
Implementation Method 2
depositing a silicon-containing material on the substrate
Implementation Method 3
forming plasma effluents of the oxygen-containing precursor
Implementation Method 4
contacting the silicon-containing material with the plasma effluents of the oxygen-containing precursor to oxidize the silicon-containing material
Implementation Method 5
forming plasma effluents of the fluorine-containing precursor
Implementation Method 6
contacting the silicon-and-oxygen-containing material with plasma effluents of the fluorine-containing precursor. The contacting may etch the 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. The methods may include depositing a silicon-containing material on the substrate. The methods may include providing an oxygen-containing precursor to the processing region, forming plasma effluents of the oxygen-containing precursor, and contacting the silicon-containing material with the plasma effluents of the oxygen-containing precursor to form a silicon-and-oxygen-containing material. The methods may include providing a fluorine-containing precursor to the processing region, forming plasma effluents of the fluorine-containing precursor, and etching the silicon-and-oxygen-containing material from a top, a sidewall, or both of the feature with the plasma effluents of the fluorine-containing precursor.