Tungsten Deposition Step Coverage in High Aspect Ratio Features
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Solution Overview
Problem
Conventional chemical vapor deposition processes for tungsten-containing materials often result in seam formation within high aspect ratio features, leading to increased resistance, contamination, and performance degradation in semiconductor circuits due to poor step coverage and overhangs during deposition.
Innovation Solution
Implementing a selective removal process during feature filling, where a portion of the deposited tungsten-containing layer is removed more extensively near the feature opening than inside, to improve step coverage and reduce seam formation by controlling etchant flow rates and temperatures to achieve mass-transport limited etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CVD deposition is used to fill high aspect ratio features, then the features can be filled with tungsten-containing materials, but seams form inside the features leading to high resistance and performance degradation
Solution Approach 1:
A nucleation layer is deposited first to prepare the surface for subsequent tungsten deposition, creating a foundation that promotes uniform growth and prevents seam formation during the filling process
Solution Approach 2:
The deposition process uses pulsed sequences of tungsten precursor and hydrogen gas, allowing controlled incremental deposition that prevents seam formation while ensuring complete feature filling
2Productivity
If the substrate is heated to process temperature in a deposition chamber, then tungsten-containing materials can be deposited, but overhangs form during deposition causing poor step coverage
Solution Approach 1:
The process creates different deposition conditions at different locations within the chamber, with features receiving more material than the field region, achieving superior step coverage through localized deposition enhancement
Solution Approach 2:
The deposition process utilizes controlled heating to process temperature and adjusted gas flow rates to optimize the balance between deposition rate and step coverage, preventing overhang formation while maintaining productivity
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 reduces seam sizes and moves the reference point further away from the field region, enhancing the filling of high aspect ratio features with improved step coverage and minimizing performance issues in semiconductor circuits.
Implementation Method 1
depositing a layer of a tungsten-containing material on a substrate containing one or more high aspect ratio features via a chemical vapor deposition reaction
Implementation Method 2
the tungsten-containing bulk layer is formed by the reduction of tungsten hexafluoride (WF6) with hydrogen (H2)
Implementation Method 3
controlling etchant flow rates and temperatures to achieve mass-transport limited etching
Data Source
AI summary
Methods of filling high aspect ratio features provided on partially manufactured semiconductor substrates with tungsten-containing materials are provided. In certain embodiments, the methods include partial filling a high aspect ratio feature with a layer of tungsten-containing materials and selective removal of the partially filled materials from the feature cavity. Substrates processed using these methods have improved step coverage of the tungsten-containing materials filled into the high aspect ratio features and reduced seam sizes.