Semiconductor Wafer Cleaning with Dynamic Spin Speed Control
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Solution Overview
Problem
Conventional methods for cleaning semiconductor wafers result in surface roughness deterioration and increased surface defects such as water marks and micro particles due to constant rotational speeds during hydrofluoric acid treatment.
Innovation Solution
A method involving a semiconductor wafer with an oxide film, where the rotational speed is increased to 300 rpm or more before the contact angle with pure water exceeds 5°, followed by a reduction to 100 rpm or less to completely remove the oxide film, using hydrofluoric acid as the cleaning solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotational speed is maintained at 300 rpm or more during hydrofluoric acid treatment, then the chemical solution is surely distributed to the outer peripheral portion of the wafer, but micro particles and water marks increase, causing wafer quality deterioration
Solution Approach 1:
The patent applies dynamic speed adjustment by changing the rotational speed from 300 rpm or more during hydrofluoric acid treatment to 100 rpm or less during subsequent pure water and ozone water treatments. This dynamic adjustment resolves the contradiction by using high speed for solution distribution and low speed for preventing particle and water mark formation.
2Manufacturing precision
If the rotational speed is reduced to 100 rpm or less during hydrofluoric acid treatment, then surface roughness is maintained, but the solution remains at the wafer outer periphery causing local haze
Solution Approach 1:
The patent uses dynamic speed adjustment, setting rotational speed to 300 rpm or more during hydrofluoric acid treatment to ensure solution distribution and prevent haze, then reducing to 100 rpm or less during subsequent treatments to maintain surface roughness and prevent particle formation.
Solution Approach 2:
The patent applies preliminary action by first performing hydrofluoric acid treatment at high rotational speed to remove the oxide film before subsequent treatments. This preliminary high-speed treatment ensures complete oxide removal and solution distribution, preventing haze formation that would occur with low-speed treatment.
3Ease of operation
If constant rotational speed is used throughout the cleaning process, then the process is simple to operate, but surface defects such as water marks and micro particles increase
Solution Approach 1:
The patent implements dynamic rotational speed control, adjusting from 300 rpm or more during hydrofluoric acid treatment to 100 rpm or less during pure water and ozone water treatments. This resolves the contradiction by optimizing speed for each treatment stage to minimize surface defects while maintaining operational feasibility.
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 surface roughness deterioration and surface defect generation, ensuring high-quality semiconductor wafers by optimizing the rotational speed during oxide film removal.
Implementation Method 1
an oxide film formed on the surface of a semiconductor wafer is generally removed with a cleaning solution such as hydrofluoric acid (HF) from the semiconductor wafer
Implementation Method 2
the rotation number is set constant, for example, at 300 rpm or more, to surely distribute the chemical solution to the outer peripheral portion of a wafer
Data Source
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AI summary
The present invention is a method for cleaning a semiconductor wafer, including: supplying a semiconductor wafer whose surface has an oxide film formed thereon with a cleaning solution capable of removing the oxide film; and cleaning, while rotating, the semiconductor wafer to remove the oxide film formed on the surface of the semiconductor wafer. The oxide film is removed such that a rotational speed of the semiconductor wafer is 300 rpm or more after the cleaning with the cleaning solution is started and before a water-repelling surface is attained, and then the rotational speed of the semiconductor wafer is changed to 100 rpm or less to completely remove the oxide film. This provides a method for cleaning a semiconductor wafer by which both surface roughness improvement and surface defect suppression can be achieved.