Molybdenum Gap Fill Deposition for High-Aspect-Ratio Features
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Solution Overview
Problem
Conventional molybdenum-based precursors used in semiconductor fabrication concurrently etch and deposit gap fill materials, leading to reduced density and efficiency due to byproduct retention, which complicates the filling of high aspect ratio features in substrates.
Innovation Solution
A two-step deposition process is employed, involving a first deposition process with a low flow rate ratio of molybdenum-containing precursor to reducing agent for nucleation layer formation, followed by a second process with a higher flow rate ratio to fill the feature with molybdenum gap fill material, maintaining vacuum throughout to minimize etching and byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a molybdenum-based precursor is used to fill high aspect ratio features, then the feature filling capability is improved, but the gap fill material density is reduced due to concurrent etching and byproduct retention
Solution Approach 1:
The deposition process is divided into multiple sequential steps with different flow rate ratios. The first step uses a lower ratio (1×10−8 to 2×10−3) for initial nucleation, while subsequent steps use higher ratios (2×10−5 to 1×10−2) for complete feature filling. This segmentation allows optimization of each step for its specific purpose, achieving both good nucleation and high density fill.
Solution Approach 2:
The flow rate ratio of molybdenum-containing precursor to reducing agent is dynamically adjusted during the deposition process. The ratio transitions from lower values during nucleation to higher values during the filling phase, enabling the process to adapt to different deposition stages and achieve optimal results for both nucleation and density.
2Device complexity
If a conventional single-step deposition process is used, then the process complexity is reduced, but the incubation delay increases and byproduct formation occurs
Solution Approach 1:
The deposition process is segmented into distinct steps with optimized parameters for each phase. The first step focuses on nucleation with appropriate flow rate ratios, while subsequent steps focus on rapid filling. This segmentation eliminates the incubation delay by ensuring proper nucleation before filling begins, while the overall process remains integrated and manageable.
3Speed
If a high flow rate ratio of molybdenum-containing precursor to reducing agent is used, then the deposition speed is improved, but etching of the gap fill material occurs
Solution Approach 1:
The flow rate ratio is dynamically controlled based on the deposition stage. During the nucleation phase, a lower ratio (1×10−8 to 2×10−3) prevents etching while establishing proper nucleation. During the subsequent filling phase, the ratio is increased (2×10−5 to 1×10−2) to achieve high deposition speed. This dynamic adjustment eliminates etching during nucleation while enabling rapid filling afterward.
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 reduces incubation delay, minimizes byproduct formation, and enhances the ability to completely fill high aspect ratio features, thereby improving manufacturing efficiency and reducing costs.
Implementation Method 1
A nucleation layer is deposited on a surface of a feature formed in a surface of a substrate by a first deposition process. The first deposition process including flowing a molybdenum-containing precursor and a reducing agent precursor gas into a processing chamber
Implementation Method 2
At least a portion of the feature is filled with a molybdenum gap fill material by exposing the deposited nucleation layer feature to a second deposition process. The second deposition process including flowing the molybdenum-containing precursor and the reducing agent precursor gas into a processing chamber
Implementation Method 3
A grain layer including tungsten is deposited over at least a portion of a feature formed in a surface of a substrate by use of a physical vapor deposition (PVD) process
Data Source
AI summary
The present disclosure provides methods for processing a semiconductor device substrate. A nucleation layer is deposited on a surface of a feature formed in a surface of a substrate by a first deposition process. The first deposition process including flowing a molybdenum-containing precursor and a reducing agent precursor gas into a processing chamber at a first flow rate ratio of about 1×10−8 to about 2×10−3 of molybdenum-containing precursor to reducing agent. At least a portion of the feature is filled with a molybdenum gap fill material by exposing the deposited nucleation layer feature to a second deposition process. The second deposition process including flowing the molybdenum-containing precursor and the reducing agent precursor gas into a processing chamber at a second flow rate ratio of about 2×10−5 to about 1×10−2 of molybdenum-containing precursor to reducing agent, wherein the second flow rate ratio is greater than the first flow rate ratio.