Substrate Cleaning Apparatus Inert Atmosphere
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Solution Overview
Problem
Conventional substrate cleaning apparatuses fail to clean large, hydrophobic semiconductor wafers uniformly and prevent copper corrosion effectively, especially when using pure water, due to non-uniform liquid flow and oxygen exposure.
Innovation Solution
A substrate cleaning apparatus with a process chamber that conveys substrates horizontally, using a non-contact cleaning unit with a two-fluid jet or ultrasonic cleaning, and an inert gas blowing unit to create an inert atmosphere, preventing oxygen ingress and ensuring uniform cleaning and drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a substrate is cleaned by rotating it while in contact with a cleaning liquid, then cleaning action is provided, but uniform cleaning over the entire surface becomes difficult due to different flow velocities and liquid film thicknesses at different portions
Solution Approach 1:
The patent replaces the mechanical rotation system with a fluid dynamic system. Instead of rotating the substrate to achieve cleaning uniformity, the invention uses a tangential flow field created by a shower head that delivers cleaning liquid with controlled swirl flow. This fluid-based approach eliminates the need for mechanical rotation while achieving uniform cleaning across the entire substrate surface, including edge portions.
Solution Approach 2:
The invention employs hydraulic principles by using a shower head that generates a tangential flow field through controlled liquid delivery. The shower head design creates a swirling flow pattern that ensures uniform distribution of cleaning liquid across the substrate surface, leveraging fluid dynamics rather than mechanical motion to achieve cleaning uniformity.
2Manufacturing precision
If pure water is used for cleaning copper-containing substrates, then cleaning effectiveness is improved, but copper corrosion occurs due to oxygen dissolution from air
Solution Approach 1:
The patent implements an inert atmosphere by introducing nitrogen gas into the process chamber to displace oxygen. By maintaining a low oxygen concentration environment during the cleaning process, the invention prevents copper corrosion while allowing the use of pure water for effective cleaning. The nitrogen atmosphere eliminates the harmful oxidation reaction that would otherwise occur between dissolved oxygen and copper surfaces.
3Adaptability or versatility
If the process chamber volume is increased to accommodate substrate rotation mechanisms, then substrate cleaning capability is improved, but creating a desired inert gas atmosphere becomes difficult
Solution Approach 1:
By replacing the substrate rotation mechanism with a stationary substrate approach using tangential flow cleaning, the invention significantly reduces the required process chamber volume. This compact design makes it feasible to maintain a controlled inert gas atmosphere, as smaller chambers are more effective at maintaining uniform gas composition and oxygen exclusion.
4Productivity
If a large substrate diameter of 450 mm is processed, then productivity is improved, but non-uniformity of water wetting properties increases making uniform cleaning further difficult
Solution Approach 1:
The shower head is designed to generate a tangential flow field that creates a swirling motion of the cleaning liquid across the large substrate surface. This hydraulic approach ensures that even on 450 mm diameter substrates with hydrophobic low-k films, the cleaning liquid is distributed uniformly, overcoming the increased non-uniformity of water wetting properties that occurs with larger substrate sizes.
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
The apparatus achieves uniform cleaning of large, hydrophobic substrates without rotating them, reducing process chamber volume and minimizing copper corrosion by maintaining a low-oxygen inert gas atmosphere, ensuring efficient and corrosion-free cleaning.
Implementation Method 1
a two-fluid jet cleaning unit configured to clean the surface of the substrate with two-fluid jet stream comprising a fluid mixture of gas and liquid
Implementation Method 2
an ultrasonic cleaning unit configured to clean the surface of the substrate with ultrasonic waves propagated through a cleaning liquid
Implementation Method 3
an inert gas blowing unit configured to blow an inert gas toward the front and reverse surfaces of the substrate which has been cleaned in the cleaning unit to produce an inert gas atmosphere in the process chamber while drying the substrate with the inert gas
Data Source
AI summary
A substrate cleaning apparatus cleans a surface of a substrate such as a semiconductor wafer and dries the substrate. The substrate cleaning apparatus includes a process chamber having a substrate conveying unit configured to hold a substrate horizontally with its upper surface facing upwardly and to convey the substrate in one direction, and a cleaning unit configured to clean the surface of the substrate in non-contact state by supplying a cleaning liquid to the surface of the substrate which is moving in the process chamber. The substrate apparatus has an inert gas blowing unit configured to blow an inert gas toward the front and reverse surfaces of the substrate which has been cleaned in the cleaning unit to produce an inert gas atmosphere in the process chamber while drying the substrate with the inert gas.