Tungsten Embedding in High Aspect Ratio Recesses
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Solution Overview
Problem
In semiconductor manufacturing, embedding tungsten into recesses with high aspect ratios on substrates is challenging due to the risk of opening blockage and fluorine atom diffusion, which can degrade the insulation performance of silicon oxide films by forming voids and hydrogen fluoride, leading to leakage current issues.
Innovation Solution
A method involving the formation of a lower tungsten layer using a fluorine-free tungsten precursor gas on an aluminum oxide layer, followed by a main tungsten layer with a fluorine-containing precursor gas, and an optional upper tungsten layer using a fluorine-free precursor, to minimize fluorine atom diffusion and void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fluorine-containing tungsten precursor gas is supplied to form a tungsten layer, then tungsten embedding is achieved, but fluorine atoms diffuse to the silicon oxide film causing insulation performance degradation
Solution Approach 1:
The tungsten layer formation process is divided into two distinct stages: first forming a lower tungsten layer using fluorine-free precursor gas, then forming an upper tungsten layer using fluorine-containing precursor gas. This segmentation prevents fluorine diffusion to the silicon oxide film while achieving complete tungsten embedding in the recess.
Solution Approach 2:
A lower tungsten layer is formed in advance using fluorine-free tungsten precursor gas before forming the main tungsten layer with fluorine-containing gas. This preliminary action creates a barrier that prevents subsequent fluorine atom diffusion to the silicon oxide film.
2Manufacturing precision
If tungsten is embedded into high aspect ratio recesses, then wiring metal embedding is achieved, but opening blockage occurs forming voids
Solution Approach 1:
The tungsten deposition process is segmented into multiple stages with different precursor gases and process conditions. The lower tungsten layer is formed with fluorine-free gas to ensure good adhesion and prevent void formation, while the upper layer completes the embedding, thereby improving reliability in high aspect ratio recesses.
3Manufacturing precision
If fluorine-containing tungsten precursor gas is used, then tungsten layer formation is achieved, but hydrogen fluoride is formed causing leakage current
Solution Approach 1:
The tungsten layer formation is divided into two parts: the lower layer uses fluorine-free precursor gas to avoid hydrogen fluoride generation, while the upper layer uses fluorine-containing gas for complete embedding. This segmentation reduces harmful hydrogen fluoride formation while maintaining manufacturing precision.
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 prevents fluorine atom diffusion to the silicon oxide film, maintaining insulation performance and reducing the risk of seam formation, thereby enhancing the electrical characteristics of semiconductor devices.
Implementation Method 1
forming a lower tungsten layer by supplying a fluorine-free tungsten precursor gas containing a tungsten compound that does not contain fluorine atoms to a top surface of an aluminum oxide layer
Implementation Method 2
embedding tungsten into the recess by supplying a tungsten precursor gas containing a tungsten compound that contains fluorine atoms to a top surface of the lower tungsten layer
Data Source
AI summary
A method of embedding tungsten into a recess formed on a substrate, the method includes forming a lower tungsten layer by supplying a fluorine-free tungsten precursor gas containing a tungsten compound that does not contain fluorine atoms to a top surface of an aluminum oxide layer formed inside the recess, and embedding tungsten into the recess by supplying a tungsten precursor gas containing a tungsten compound that contains fluorine atoms to a top surface of the lower tungsten layer to form a main tungsten layer.