Gravity-Driven ALD Tunnel with Gas Bearings
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Solution Overview
Problem
Current atomic layer deposition (ALD) systems have limited throughput, which is insufficient for meeting the increasing demand for solar cell panels and other applications, requiring a more efficient and simpler apparatus design to enhance deposition capacity.
Innovation Solution
The design features a process tunnel with parallel walls and gas injection channels that create zones for precursor and purge gases, allowing substrates to be conveyed through a series of segments for continuous deposition, utilizing gravity to drive substrate movement and eliminate the need for a separate conveyor system, thereby increasing throughput while maintaining simplicity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-wafer ALD systems are used, then film deposition quality is maintained, but throughput is limited to about 60 wafers per hour
Solution Approach 1:
The process tunnel is divided into multiple sequential zones (first precursor gas zone, first purge gas zone, second precursor gas zone, second purge gas zone) that process different portions of the substrate simultaneously. This spatial segmentation allows multiple deposition cycles to occur in parallel across different substrate regions, dramatically increasing throughput without requiring multiple complete substrate processing lines.
Solution Approach 2:
The invention transitions from processing substrates sequentially through a single deposition zone to processing multiple substrate regions simultaneously through parallel gas injection channels arranged in different spatial dimensions. The gas injection channels are distributed across the tunnel cross-section, enabling multi-dimensional parallel processing that increases throughput while maintaining a relatively simple linear tunnel structure.
2Productivity
If apparatus complexity is reduced for simplicity and reliability, then manufacturing and maintenance costs decrease, but throughput capacity is limited
Solution Approach 1:
The process tunnel serves multiple functions simultaneously: it acts as the processing chamber, the substrate support structure, and the gas distribution system. The gas injection channels are integrated directly into the tunnel walls, eliminating the need for separate gas distribution manifolds and reducing mechanical complexity while enabling high-throughput processing through efficient gas delivery to multiple substrate regions.
Solution Approach 2:
The system uses the substrate's own geometry and the natural flow of gases through the tunnel to achieve processing. The flat substrate accommodated between the parallel walls naturally presents multiple surfaces to the sequentially injected precursor and purge gases, eliminating the need for complex substrate manipulation mechanisms or multiple processing stations.
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 significantly enhances the throughput capacity of ALD systems, enabling the efficient deposition of films with precise control and minimal complexity, addressing the need for higher production rates in industries like solar cells without increasing maintenance and operational costs.
Implementation Method 1
The gas injection channels in the first, lower wall are configured to provide a first, lower gas bearing, while the gas injection channels in the second, upper wall are configured to provide a second, upper gas bearing. The gas bearings are configured to floatingly support and accommodate substrates.
Implementation Method 2
Viewed in the transport direction, at least a portion of the process tunnel has a downward slope (α), so as to enable gravity driven transport of substrates through said at least one process tunnel portion.
Implementation Method 3
A series of sequential steps in which a surface of the substrate is exposed to all precursors is called a deposition cycle. Each deposition cycle grows a single monolayer of film, or a fraction of a monolayer. This is due to the fact that, in ALD, film growth depends on chemisorption, a process whereby a precursor molecule adheres to a substrate's surface through the formation of a chemical bond
Data Source
AI summary
An atomic layer deposition apparatus for depositing a film in a continuous fashion is described. The apparatus includes a downwardly sloping process tunnel, extending in a transport direction and bounded by at least two tunnel walls. Both walls are provided with a plurality of gas injection channels, whereby the gas injection channels in at least one of the walls, viewed in the transport direction, are connected successively to a first precursor gas source, a purge gas source, a second precursor gas source and a purge gas source respectively, so as to create a series of tunnel segments that—in use—comprise successive zones containing a first precursor gas, a purge gas, a second precursor gas and a purge gas, respectively. The downward slope of the process tunnel enables gravity to drive the floatingly supported substrates through the successive segments, causing the atomic layer deposition of a film onto the substrates.