Substrate Cleaning Nozzle Control for Liquid Break Prevention
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Solution Overview
Problem
The challenge in cleaning semiconductor substrates is the formation of residues due to 'liquid break' phenomena, where cleaning liquids remain on the surface and dry, leading to reduced yield and throughput, especially when using high water repellent resists with large contact angle differences between exposed and unexposed portions.
Innovation Solution
A substrate cleaning apparatus that uses a combination of cleaning liquid and gas nozzles to sequentially discharge cleaning liquids and nitrogen gas onto the substrate, with controlled nozzle movements and positions to create a dry region, gradually reducing the distance between the gas nozzle and the liquid interface, enhancing the cleaning effect and preventing residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the scan speed of the cleaning liquid nozzle is decreased to reduce liquid remnants, then the cleaning effectiveness improves, but the throughput of the apparatus is reduced
Solution Approach 1:
The cleaning process is divided into multiple stages: initial cleaning with cleaning liquid, intermediate drying with gas flow, and final cleaning with reduced scan speed. This segmentation allows different parameters to be optimized for each stage, achieving both high cleaning effectiveness and maintained throughput.
Solution Approach 2:
Gas is discharged preliminarily to create a dry region and reduce liquid remnants before the cleaning liquid nozzle completes its scanning. This preliminary drying action prevents liquid break phenomena and reduces the need for slow scanning, thereby maintaining throughput while ensuring cleaning effectiveness.
2Manufacturing precision
If the distance between the gas nozzle and the liquid interface is reduced to enhance cleaning effect, then the cleaning effectiveness improves, but the risk of gas interfering with cleaning liquid distribution increases
Solution Approach 1:
The gas nozzle is positioned close to the liquid interface only in specific regions where liquid remnants are most problematic. The gas flow is localized to create dry regions at the liquid-gas interface without disrupting the overall cleaning liquid distribution across the substrate surface.
Solution Approach 2:
The gas flow acts as an intermediary between the cleaning liquid and the substrate surface. It mediates the drying process by creating a gas barrier that prevents liquid remnants from adhering to the substrate, while the cleaning liquid continues to be distributed uniformly by the cleaning liquid nozzle.
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 effectively suppresses liquid remnants and improves cleaning efficiency, maintaining high throughput by ensuring thorough drying and reducing pattern defects on semiconductor wafers.
Implementation Method 1
discharging a nitrogen gas to a central portion of the substrate to form a core of a dry region
Implementation Method 2
a cleaning liquid such as pure water is supplied to the substrate while the substrate is being rotated to wash away a dissolution product from the front surface of the substrate
Implementation Method 3
cleaning a front surface of a substrate with a cleaning liquid while rotating the substrate
Data Source
AI summary
A cleaning liquid and a gas are discharged in sequence to a central portion of a substrate while the substrate is being rotated, and after nozzles that discharge them are moved to a peripheral edge side of the substrate, discharge of the cleaning liquid is switched to a second cleaning liquid nozzle set at a position deviated from a movement locus of the first cleaning liquid nozzle. Both of the nozzles are moved toward the peripheral edge side of the substrate while discharging the cleaning liquid and discharging the gas so that a difference between a distance from the discharge position of the second cleaning liquid nozzle to the central portion of the substrate and a distance from the discharge position of the gas nozzle to the central portion of the substrate gradually decreases.