Dry Ice Wafer Cleaning With Vertical Handling to Cut Residual Particles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional dry ice cleaning methods for semiconductor wafers face challenges in effectively removing particles and burrs, leading to reduced yield and device characteristics due to residual impurities, especially with the risk of ice formation from moisture interaction and limitations in cleaning effectiveness when the wafer surface is horizontally positioned.
Innovation Solution
A dry ice cleaning apparatus with a transfer robot that holds the semiconductor wafer non-horizontally and injects dry ice from a specific angle, combined with a fan filter unit for purifying gas circulation, to effectively remove impurities using high-purity nitrogen gas or clean dry air, ensuring stable wafer support and continuous cleaning of multiple wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dry ice cleaning is performed with the wafer surface positioned horizontally, then the cleaning process is simple to operate, but particles and burrs cannot be effectively removed and remain on the wafer surface
Solution Approach 1:
The patent inverts the conventional horizontal wafer positioning to a vertical positioning with the cleaning surface facing upward. This inversion allows gravity to assist in removing particles and burrs from the wafer surface, significantly improving particle removal effectiveness while maintaining operational simplicity through automated robot handling.
Solution Approach 2:
The patent changes the wafer orientation from a two-dimensional horizontal plane to a three-dimensional vertical configuration. By positioning the wafer vertically with the cleaning surface facing upward, the system utilizes the vertical dimension to enhance cleaning effectiveness through gravity-assisted particle removal while maintaining ease of operation via robotic automation.
2Manufacturing precision
If dry ice is injected at high velocity to improve particle removal, then cleaning effectiveness increases, but the wafer surface may deform or get damaged
Solution Approach 1:
The patent changes the physical state of the cleaning medium from solid or liquid to gas phase. By using gaseous dry ice (carbon dioxide gas) instead of solid or liquid cleaning agents, the system achieves effective particle removal through gas flow dynamics while the gas phase nature prevents mechanical impact damage to the wafer surface.
Solution Approach 2:
The patent replaces mechanical impact-based cleaning (high velocity solid or liquid injection) with a gas flow-based cleaning system. The gaseous dry ice utilizes fluid dynamics and gas flow patterns to remove particles, substituting mechanical impact with aerodynamic forces that are effective yet non-damaging to the wafer surface.
3Device complexity
If dry ice cleaning is performed in a conventional setup, then the process is simple, but moisture in the air forms ice and reduces cleaning performance
Solution Approach 1:
The patent creates an inert atmosphere by introducing dry air or nitrogen gas into the cleaning chamber. This inert environment prevents moisture from the ambient air from condensing and forming ice on the wafer surface or in the cleaning system, ensuring consistent cleaning performance while maintaining system simplicity through integrated gas supply.
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 significantly reduces residual particles and burrs on the wafer surface, enhancing yield and device characteristics by ensuring effective and continuous cleaning of large quantities of semiconductor wafers without deformation or damage.
Implementation Method 1
dry ice has a very low temperature of −79° C., so if there is moisture around it, it will form ice, and the dry ice itself will sublimate
Implementation Method 2
injects dry ice onto the semiconductor wafer... removes impurities attached to a cleaning surface
Implementation Method 3
using high-purity nitrogen gas or clean dry air, it is possible to suppress the formation of ice derived from moisture in the air
Data Source
AI summary
An object of the present invention is to provide a dry ice cleaning apparatus for a semiconductor wafer and a method for cleaning a semiconductor wafer that can reduce the amount of particles remaining on the surface of a semiconductor wafer, suppress a decrease of cleaning effects due to ice formation, and continuously and effectively clean a large amount of semiconductor wafers. The present invention provides a dry ice cleaning apparatus for a semiconductor wafer including a cleaning chamber (1) into which the semiconductor wafers (W) are sequentially carried in and which has an internal space (11) for cleaning the semiconductor wafers (W), an inject cleaning nozzle (5) that is disposed in the internal space (11) of the cleaning chamber (1) and injects the dry ice (D) toward the cleaning surface of the semiconductor wafer (w), and a transfer robot (2) that is disposed in the internal space (11) of the cleaning chamber (1) and sequentially carries the semiconductor wafers (W) from the outside of the cleaning chamber (1) into the internal space (11); and wherein while the transfer robot (2) holding the semiconductor wafer (W) carried into the internal space (11) non-horizontally, the inject cleaning nozzle (5) injects the dry ice (D) onto the semiconductor wafer (W).