Semiconductor Wafer Cleaning via Partial Oxide Retention
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Solution Overview
Problem
Existing semiconductor wafer cleaning methods fail to simultaneously reduce metal impurity and particle levels on the wafer surface, leading to increased particle adhesion and degraded surface quality.
Innovation Solution
A method involving sequential cleaning steps of HF cleaning, ozonated water cleaning, and repeated HF cleaning, where the final HF cleaning partially retains the oxide film thickness to prevent bare surface exposure, combined with ozonated water cleaning to maintain a protective oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HF cleaning is carried out to remove metal impurities, then metal impurity level is reduced, but oxide film is entirely removed exposing bare surface that attracts particles
Solution Approach 1:
The patent applies partial action by controlling the HF cleaning process to remove only a portion of the oxide film thickness rather than completely removing it. This allows the cleaning solution to remove metal impurities incorporated in the oxide film while leaving a residual oxide layer that protects the bare surface from particle adhesion, thus resolving the contradiction between metal impurity removal and particle prevention
Solution Approach 2:
The patent changes the parameter of oxide film thickness removal from 100% to a controlled partial removal. By adjusting the HF cleaning conditions (concentration, time, temperature) to achieve partial oxide film removal, the process simultaneously reduces metal impurities while maintaining a protective oxide residue that prevents particle adhesion on the exposed surface
2Object-affected harmful factors
If ozonated water cleaning is carried out to form oxide film, then protective oxide layer is formed, but metal impurities incorporated into oxide film remain
Solution Approach 1:
The patent applies preliminary action by first forming an oxide film through ozonated water cleaning before performing HF cleaning. This preliminary oxide film formation allows subsequent HF cleaning to remove metal impurities that are incorporated into the oxide structure, while the controlled partial removal leaves a clean protective layer
Solution Approach 2:
The patent employs continuous alternating action between ozonated water cleaning (oxide formation) and HF cleaning (impurity removal). This continuous cycle of oxide formation followed by controlled partial removal with HF cleaning ensures both surface protection and metal impurity reduction are achieved through repeated useful actions
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 both metal impurity and particle levels on the semiconductor wafer surface, preventing particle adhesion and maintaining a stable oxide film for surface protection.
Implementation Method 1
the oxide film itself is removed simultaneously with the metal impurities incorporated into the oxide film
Implementation Method 2
surface oxidation treatment by ozonated water (or pure water) is carried out
Implementation Method 3
an organic material(s) attached to a surface of the semiconductor wafer is removed by the first ozonated water cleaning
Data Source
AI summary
The present invention provides a method for cleaning a semiconductor wafer, in which the method includes cleaning steps of HF cleaning, ozonated water cleaning and HF cleaning in this order at least one time, wherein in the HF cleaning carried out last in the method for cleaning the semiconductor wafer, cleaning is so carried out that an oxide film formed on a surface of the semiconductor wafer by the ozonated water is not entirely removed and to remain a part of a thickness thereof on the surface of the semiconductor wafer. As a result, a method for cleaning a semiconductor wafer in which a metal impurity level and a particle level can be reduced simultaneously in the cleaning of the semiconductor wafer is provided.