Grazing Angle Pre-Wetting Nozzle for Semiconductor Substrate Cleaning
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Solution Overview
Problem
Existing methods face challenges in achieving adequate wetting and cleaning of semiconductor substrates, particularly in recessed features, due to difficulties in removing solid contaminants and forming a continuous wetting layer, which can result in voids during electroplating processes.
Innovation Solution
The use of a pre-wetting apparatus with a process chamber and a substrate holder that includes a nozzle system to deliver pre-wetting liquid at a grazing angle of 5-45 degrees, combined with substrate rotation and modulation of rotation rates, effectively removes contaminants and forms a wetted surface suitable for electroplating by using high-velocity fan nozzles and a moveable arm to target specific areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning methods are used on substrates, then general surface cleaning is achieved, but solid contaminants in recessed features cannot be effectively removed
Solution Approach 1:
The patent applies local quality by directing liquid flow specifically into recessed features using nozzles positioned at controlled angles and distances. The liquid is targeted to impact and flow through specific difficult-to-reach areas rather than uniform coverage, enabling effective contaminant removal from recessed features while maintaining overall cleaning effectiveness.
Solution Approach 2:
The patent introduces a new dimension to cleaning by using substrate rotation in addition to controlled liquid delivery angles. This rotational movement creates dynamic flow patterns that penetrate recessed features from multiple angles over time, transforming a static cleaning approach into a dynamic multi-dimensional process that effectively reaches contaminants in hard-to-access areas.
2Manufacturing precision
If high-velocity liquid delivery is used to remove contaminants, then cleaning effectiveness improves, but difficulty in forming continuous wetting layer increases
Solution Approach 1:
The patent applies periodic action by using substrate rotation that continuously changes the orientation of recessed features relative to the liquid delivery nozzle. This periodic movement allows liquid to penetrate features from different angles over time, effectively removing contaminants while the continuous rotational motion also ensures uniform wetting distribution, preventing void formation and maintaining reliable wetting layer formation.
Solution Approach 2:
The patent maintains continuity of useful action by combining high-velocity liquid delivery with continuous substrate rotation. The rotation ensures that all areas of the substrate, including recessed features, are continuously exposed to cleaning and wetting actions. This continuous dynamic process prevents localized over-wetting or under-wetting, ensuring both effective contaminant removal and uniform continuous wetting layer formation.
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 ensures efficient removal of contaminants and formation of a continuous wetting layer across the substrate, including recessed features, enhancing the substrate's readiness for subsequent processing steps like electroplating.
Implementation Method 1
The high velocity is selected such as to remove the solid contaminants from the substrate surface (particularly contaminants adhering to the substrate in the recessed features)
Implementation Method 2
Wetting is a property of a liquid/solid interface governed by adhesive forces between the liquid and solid and cohesive forces in the liquid. Adhesive forces between the liquid and solid cause the liquid to spread across the solid surface.
Data Source
AI summary
Disclosed are pre-wetting apparatus designs and methods for cleaning solid contaminants from substrates prior to through resist deposition of metal. In some embodiments, a pre-wetting apparatus includes a process chamber having a substrate holder, and at least one nozzle located directly above the wafer substrate and configured to deliver pre-wetting liquid (e.g., degassed deionized water) onto the substrate at a grazing angle of between about 5 and 45 degrees. In some embodiments the nozzle is a fan nozzle configured to deliver the liquid to the center of the substrate, such that the liquid first impacts the substrate in the vicinity of the center and then flows over the center of the substrate. In some embodiments the substrate is rotated unidirectionally or bidirectionally during pre-wetting with multiple accelerations and decelerations, which facilitate removal of contaminants.