Ultrasonic Wafer Underside Cleaning With a Compact Partial-Contact Tank
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Solution Overview
Problem
Existing wafer cleaning apparatuses require large cleaning tanks, making them unsuitable for compact installation in processing apparatuses, and they may cause abrasion of the wafer surface during cleaning.
Innovation Solution
A compact wafer cleaning apparatus with a cleaning mechanism that uses a cleaning tank with an opening to store cleaning water higher than its top surface, combined with an ultrasonic oscillator, and a moving mechanism to move the wafer relative to the cleaning water, allowing partial contact and sweeping across the entire under surface without full immersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire wafer is immersed in cleaning water in a large cleaning tank, then the cleaning effectiveness is improved, but the apparatus size increases and compact installation becomes difficult
Solution Approach 1:
The patent applies partial action by having only a portion of the wafer (specifically the under surface) contact the cleaning water, rather than immersing the entire wafer. The cleaning tank is designed with a bottom opening that allows cleaning water to contact only the under surface of the wafer as it passes through, achieving effective cleaning while using a compact tank size.
Solution Approach 2:
The cleaning process is segmented into specific zones: the cleaning tank with its bottom opening creates a localized cleaning region, and the wafer is cleaned in a specific passage area rather than full immersion. This segmentation allows the cleaning function to be performed effectively in a compact space.
2Reliability
If a brush is used in the cleaning tank to remove particles, then particle removal capability is improved, but the risk of wafer surface abrasion increases
Solution Approach 1:
The patent replaces the mechanical brush cleaning system with a fluid-based cleaning system. Cleaning water flows through the bottom opening of the tank and contacts the wafer under surface, using fluid dynamics rather than mechanical contact to remove particles, thereby eliminating the abrasion risk associated with brushes.
Solution Approach 2:
The cleaning mechanism uses hydraulic principles by circulating cleaning water through the bottom opening of the tank. The water flow contacts the wafer under surface and removes particles through fluid action, replacing mechanical brush contact with a hydraulic cleaning approach that prevents surface damage.
3Reliability
If the wafer is fully immersed in cleaning water, then complete coverage cleaning is achieved, but the cleaning tank volume must be large
Solution Approach 1:
The patent implements partial action by designing the cleaning system to contact only the necessary portion of the wafer (the under surface) with cleaning water. The bottom opening of the tank creates a focused cleaning zone that treats the under surface effectively without requiring full wafer immersion, thus reducing the required tank volume.
Solution Approach 2:
The cleaning system uses dynamic motion where the wafer moves through the cleaning tank rather than being stationary. This allows the under surface of the wafer to contact the cleaning water in a controlled manner as it passes through, achieving effective cleaning coverage with a compact tank design.
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 solution enables a compact design that effectively cleans the wafer surface while preventing abrasion, allowing for efficient installation in processing apparatuses without increasing their size.
Implementation Method 1
an ultrasonic oscillator arranged at the cleaning tank and configured to propagate ultrasonic oscillation to the cleaning water
Implementation Method 2
a raised surface of cleaning water stored in the cleaning tank, which is raised by its surface tension, to come into contact with the under surface of the wafer
Data Source
AI summary
A wafer cleaning apparatus includes: a holding pad configured to hold a top surface of a wafer; a cleaning mechanism configured to clean part of an under surface of the wafer held on the holding pad; and a moving mechanism configured to relatively move the holding pad and the cleaning mechanism in a horizontal direction, wherein the cleaning mechanism includes: a cleaning tank; a cleaning water supply configured to supply cleaning water to the cleaning tank; and an ultrasonic oscillator arranged at the cleaning tank and configured to propagate ultrasonic oscillation to the cleaning water; and wherein the moving mechanism is configured to move the holding pad holding the wafer, whose under surface is partially in contact with the cleaning water raised higher than an opening of the cleaning tank, so as to clean the under surface of the wafer.