Vertical Wafer Cleaning with Pulsed Liquid Jet
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Solution Overview
Problem
Existing wet cleaning systems for semiconductor wafers, particularly those with horizontal orientations, face inefficiencies in removing contaminants from the upper surface and often result in secondary contamination, large operational spans, and limited application specificity.
Innovation Solution
A compact, vertically oriented apparatus utilizing separate end-effectors and rapid-pulse harmonic spray technology with pulsed jets for efficient contaminant removal, combined with a turbo-spin dry module for effective drying, optionally using nitrogen to prevent water spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If horizontal orientation cleaning systems are used, then the apparatus structure is simpler, but contaminant removal efficiency from upper surface is poor
Solution Approach 1:
The patent inverts the conventional horizontal cleaning orientation to a vertical orientation. The wafer is held vertically by a wafer holder, and the cleaning jet is directed at the wafer surface from above, allowing gravity to assist in removing contaminants from the upper surface while improving overall cleaning efficiency without excessive structural complexity
Solution Approach 2:
The patent transitions from horizontal to vertical orientation, adding a gravitational dimension to the cleaning process. This dimensional change allows the cleaning jet to act from above while contaminants are removed downward by gravity, creating a more effective cleaning mechanism that addresses the upper surface contamination problem
2Manufacturing precision
If continuous liquid jet is used for cleaning, then cleaning coverage is improved, but secondary contamination and water spots increase
Solution Approach 1:
The patent employs pulsed liquid jet cleaning instead of continuous jet. The cleaning liquid is delivered in periodic pulses, allowing the wafer to be cleaned thoroughly while minimizing residual liquid that could cause water spots or secondary contamination. The pulsed action maintains cleaning coverage while reducing harmful effects
Solution Approach 2:
The patent uses a series of rapid pulsed jets that maintain continuous cleaning action on the wafer surface. The pulses are frequent enough to ensure complete coverage and removal of contaminants, yet spaced enough to allow evaporation and prevent water spot formation, achieving both thorough cleaning and minimal secondary contamination
3Manufacturing precision
If vertical orientation apparatus is used, then contaminant removal efficiency is improved, but apparatus occupies more vertical space
Solution Approach 1:
The patent segments the cleaning system into distinct functional components: a wafer holder for vertical positioning, a cleaning jet delivery system, and a wafer support structure. This segmentation allows the vertical orientation to be achieved while managing the overall apparatus height and space requirements through modular design
Solution Approach 2:
The wafer holder in the vertical orientation system serves multiple functions: it positions the wafer vertically for improved cleaning, supports the wafer during the cleaning process, and facilitates easy loading and unloading. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in vertical space occupation
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 high cleaning efficiency with vertical orientation, efficient contaminant removal, and rapid drying, enhancing production efficiency while minimizing secondary contamination and operational complexity.
Implementation Method 1
A pulsed liquid jet is used to clean the wafer surface
Implementation Method 2
The wafer is then picked up by a second end effector and introduced into a turbo-spin dry module where it is spin dried without splash back
Data Source
AI summary
An apparatus for cleaning flat objects such as semiconductor wafers with a pulsed liquid jet emitted from a group of nozzles that may be installed on one or on both sides of the wafer installed in a vertically arranged rotating chuck. The apparatus is comprised of a series of individual processing units, such as a loading unit, cleaning units, drying unit, and an unloading unit arranged circumferentially around a universal industrial robot capable of reaching any of the units and transferring the wafers between the units. Drying is carried out in a horizontal position of the wafer and may combine spin-dry with chemical treatment for accelerating the drying process and for improving quality of the drying process. All units are located in a sealed enclosure with a controlled purity of the atmosphere inside the enclosure. Method of cleaning is also disclosed.