Semiconductor Wafer Cleaning Ozone Water Flow Control
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Solution Overview
Problem
Conventional methods for cleaning semiconductor wafers using ozone water result in deposits forming on the wafer surface along the direction of the rising ozone flow, which are difficult to remove and persist even after multiple cleaning processes.
Innovation Solution
A method involving the temporary cessation of ozone water supply during wafer immersion in the cleaning tank to suppress the rising flow, followed by resupplying ozone water to maintain detergency and prevent re-deposition of particles on the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ozone water is supplied continuously with rising flow during wafer cleaning, then detergency is maintained, but deposits form on the wafer surface along the flow direction
Solution Approach 1:
The patent applies periodic action by alternating between a first cleaning process with rising ozone water flow and a second cleaning process without rising flow. During the first process, ozone water is supplied to maintain detergency. During the second process, supply is stopped or flow rate is reduced to prevent particle diffusion and re-deposition. This periodic alternation resolves the contradiction by achieving both effective cleaning and deposit prevention.
2Productivity
If ozone water flow rate is increased to improve cleaning efficiency, then cleaning speed increases, but particle diffusion and re-deposition increase
Solution Approach 1:
The patent uses periodic action by implementing two distinct cleaning processes with different flow conditions. The first process uses high flow rate for efficient particle removal, while the second process uses stopped or reduced flow to prevent particle diffusion. This temporal separation allows high cleaning efficiency without excessive particle diffusion.
Solution Approach 2:
The cleaning process is segmented into distinct stages: a first cleaning process with rising flow for particle removal, and a second cleaning process without rising flow for preventing re-deposition. By dividing the continuous cleaning process into separate functional stages, the patent achieves both high cleaning efficiency and minimal particle diffusion.
3Manufacturing precision
If multiple cleaning processes are performed to remove deposits, then cleaning thoroughness improves, but processing time increases
Solution Approach 1:
The patent merges particle removal and deposit prevention functions into a single integrated cleaning cycle by alternating between two cleaning processes. The first process removes particles while the second prevents re-deposition, achieving thorough cleaning in one combined cycle rather than requiring multiple separate cleaning operations.
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
Effectively reduces deposits on the wafer surface by preventing particles from diffusing and adhering back during the cleaning process, improving surface cleanliness.
Implementation Method 1
after forming an oxide film on the wafer surface by immersing and oxidizing the semiconductor wafer in the ozone water
Implementation Method 2
the semiconductor wafer is cleaned by the rising flow of the ozone water from the lower part of the cleaning tank toward the upper part
Data Source
AI summary
Provided is a method for cleaning a semiconductor wafer which can effectively reduce deposits on a main surface of a wafer. A method for cleaning a semiconductor wafer of the present disclosure includes supplying ozone water into a cleaning tank from a lower part of the cleaning tank with the ozone water overflowing from the upper part of the cleaning tank to outside the cleaning tank (first step), subsequently, stopping a supply of the ozone water (second step), subsequently, immersing a semiconductor wafer into the ozone water in the cleaning tank (third step), and subsequently, resupplying the ozone water into the cleaning tank from the lower part of the cleaning tank with the ozone water overflowing again from the upper part of the cleaning tank to outside the cleaning tank (fourth step).