Silicon Wafer Cleaning Method for Polymer Removal
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Solution Overview
Problem
The RCA cleaning method for silicon wafers after mirror-polishing is insufficient in removing polymer components from the polishing slurry, as they undergo dehydration condensation reactions with the high-pH alkaline liquid, leading to incomplete removal of contaminants.
Innovation Solution
A three-stage cleaning process involving a non-ionic surfactant aqueous solution, a dissolved-ozone solution, and an ammonia-hydrogen peroxide solution, performed in succession, to effectively remove polymer components, organic contaminants, and metallic impurities, with specific concentration and temperature controls to enhance cleaning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RCA cleaning method using high-pH alkaline liquid (SC-1) is used to clean silicon wafers after mirror polishing, then general contaminants can be removed, but polymer components from the polishing slurry undergo dehydration condensation reactions and become fixed on the wafer surface, preventing complete removal of organic contaminants
Solution Approach 1:
The cleaning process is divided into three sequential stages: (1) non-ionic surfactant aqueous solution cleaning to remove polymer components and organic contaminants, (2) dissolved-ozone aqueous solution cleaning to decompose and remove surfactant residues, and (3) ammonia-hydrogen peroxide aqueous solution cleaning to remove metallic impurities. This segmentation prevents any single solution from causing polymer fixation while achieving complete contaminant removal.
Solution Approach 2:
The non-ionic surfactant aqueous solution cleaning is performed first to remove polymer components and organic contaminants before the subsequent ozone and ammonia-hydrogen peroxide cleaning steps. This preliminary action prevents polymer components from undergoing dehydration condensation reactions that would occur if high-pH alkaline solutions were applied first.
2Reliability
If multiple cleaning processes are performed in succession to improve cleanliness, then contaminant removal is enhanced, but the process complexity and time required increase
Solution Approach 1:
The cleaning process is divided into three specialized stages, each targeting specific types of contaminants with appropriate chemical solutions, achieving comprehensive cleanliness while maintaining process manageability through clear functional separation.
Solution Approach 2:
Each cleaning stage uses solutions with specifically controlled parameters (surfactant concentration of 0.001-10% by weight, ozone concentration of 1-200 ppm) to optimize contaminant removal efficiency while preventing unwanted side reactions, balancing effectiveness with process simplicity.
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 method achieves a high degree of cleanliness by decomposing and removing surfactants and metallic impurities, improving the overall cleanliness of the silicon wafer surface.
Implementation Method 1
a first cleaning process, in which, after completion of said mirror polishing, the silicon wafer is immersed in a non-ionic surfactant aqueous solution
Implementation Method 2
a second cleaning process, in which the silicon wafer, after completion of said first cleaning process, is immersed in a dissolved-ozone aqueous solution
Implementation Method 3
a third cleaning process, in which the silicon wafer, after completion of said second cleaning process, is immersed in an aqueous solution containing ammonia and hydrogen peroxide
Data Source
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AI summary
A silicon wafer cleaning method, comprising a first cleaning process, in which, after completion of mirror polishing of the surface, the silicon wafer is immersed in a non-ionic surfactant aqueous solution; a second cleaning process, in which the wafer, after completion of the first cleaning process, is immersed in a dissolved-ozone aqueous solution; and, a third cleaning process, in which the wafer, after completion of the second cleaning process, is immersed in an aqueous solution containing ammonia and hydrogen peroxide; and in which the processes are performed in succession.