Amorphous Silicon Gapfill via Oxynitride Surface Termination
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Solution Overview
Problem
Conventional methods for gapfilling high aspect ratio trenches in semiconductor devices with amorphous silicon often result in seam formation and voiding, leading to decreased throughput and potential device failure, especially when using plasma-enhanced chemical vapor deposition (PECVD), and are sensitive to the underlying surface conditions.
Innovation Solution
The method involves pretreating the substrate surface to modify hydroxy-terminated or hydrogen-terminated silicon to oxynitride-terminated silicon, followed by a flowable silicon deposition process to achieve seam-free and void-free gapfilling, using a combination of inert gases, reactive plasma, and chemical passivation to enhance the deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional PECVD or conformal deposition is used to fill high aspect ratio trenches, then the deposition process is simple and fast, but seams form in the trenches and voiding occurs at the bottom
Solution Approach 1:
The surface is pretreated with oxynitride termination before deposition to prepare the substrate in advance, preventing seam formation and voiding during subsequent gapfilling operations
Solution Approach 2:
The surface chemistry is changed from hydroxy- or hydrogen-terminated silicon to oxynitride-terminated silicon, fundamentally altering the deposition behavior to eliminate defects
2Ease of manufacture
If the underlying surface is hydroxy-terminated or hydrogen-terminated silicon, then the surface is naturally formed, but microporosity and microvoiding occur during gapfilling
Solution Approach 1:
The surface termination is chemically modified from hydroxy- or hydrogen-terminated to oxynitride-terminated, changing the surface properties to prevent microporosity and microvoiding while maintaining ease of manufacture through standardized plasma treatment
3Reliability
If PECVD is used for amorphous silicon deposition, then etch selectivity with respect to silicon oxide and amorphous carbon is good, but voiding occurs at the bottom of the trench
Solution Approach 1:
The trench surface is pretreated with oxynitride termination before PECVD deposition, preparing the surface in advance to enable void-free gapfilling while preserving the etch selectivity benefits of PECVD
Solution Approach 2:
The oxynitride-terminated surface acts as an intermediary layer that mediates between the PECVD deposition process and the trench walls, enabling complete filling without voiding
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 improves etch selectivity and results in high-quality, seam-free gapfilling with increased silicon density and uniformity, reducing microporosity and microvoiding issues, thereby enhancing semiconductor device performance and reliability.
Implementation Method 1
exposing the surface of the substrate to reactive plasma
Implementation Method 2
flowable deposition process to deposit a flowable silicon layer
Data Source
AI summary
Methods for gapfilling semiconductor device features, such as high aspect ratio trenches, with amorphous silicon (a-Si) film that involves pretreating the surface of the substrate to modify the underlying hydroxy-terminated silicon (Si—OH) or hydrogen-terminated silicon (Si—H) surface to oxynitride-terminated silicon (Si—ON) or nitride-terminated silicon (Si—N) and enhance the subsequent a-Si deposition are provided. First, a substrate having features formed in a first surface of the substrate is provided. The surface of the substrate is then pretreated to enhance the surface of the substrate for the flowable deposition of amorphous silicon that follows. A flowable deposition process is then performed to deposit a flowable silicon layer over the surface of the substrate. Methods described herein generally improve overall etch selectivity by the conformal silicon deposition and the flowable silicon deposition process to realize seam-free gapfilling between features with high quality amorphous silicon film.