Fluoride-Free Dicing Solution for Wafer Corrosion and Contaminant Control
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Solution Overview
Problem
During the dicing process of integrated circuit wafers, small contaminant residues and particles adhere to the wafer surface, particularly in bonding pads and deep trenches, making them difficult to remove and leading to corrosion issues that can cause poor bonding performance or device failure.
Innovation Solution
A dicing solution comprising dicarboxylic acids, hydroxycarboxylic acids, and specific surfactants such as phosphate esters and dodecyl benzene sulfonic acid, used in conjunction with deionized water, to inhibit the adherence of contaminants and corrosion on exposed metallization areas, while maintaining a fluoride-free and acidic pH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high purity deionized water is used as coolant during dicing, then cooling and flushing capability is improved, but static charge buildup occurs leading to contaminant accumulation and corrosion
Solution Approach 1:
The patent modifies the chemical composition parameters of the coolant by adding specific additives (corrosion inhibitors, static charge reducers, and cleaning agents) to deionized water. This transforms the pure water into a functional dicing solution that maintains cooling effectiveness while eliminating the harmful effects of static charge buildup and corrosion on exposed metallization areas.
Solution Approach 2:
The patent introduces intermediary substances (ammonium hydroxide, organic acids, and surfactants) that mediate between the water coolant and the wafer surface. These intermediaries prevent direct harmful interactions between water and exposed metallization, reducing corrosion while also preventing static charge accumulation that would attract contaminants.
2Quantity of substance
If deionized water floods the cutting area, then flushing capability is improved, but silicon particles are not completely removed and accumulate on bonding pads
Solution Approach 1:
The patent changes the chemical properties of the flushing medium by incorporating surfactants and cleaning agents into the water. This transforms ordinary water into an enhanced dicing solution that actively removes silicon particles through chemical action, improving contaminant removal effectiveness beyond what increased water volume alone could achieve.
Solution Approach 2:
The patent partially replaces mechanical flushing (relying on water flow volume) with chemical cleaning mechanisms. The surfactants and cleaning agents in the dicing solution chemically interact with and remove silicon particles, providing a more effective cleaning mechanism that doesn't depend solely on high water flow rates.
3Manufacturing precision
If dicing time is prolonged due to reduced die size, then manufacturing precision is improved, but contaminant accumulation and corrosion increase
Solution Approach 1:
The patent applies preliminary protective action by formulating a dicing solution containing corrosion inhibitors and static charge reducers before the dicing process begins. This pre-prepared solution is applied during dicing to prevent corrosion and contaminant accumulation on exposed metallization areas throughout the extended dicing time required for smaller dies.
Solution Approach 2:
The patent ensures continuous protection during the prolonged dicing process by maintaining a steady supply of the enhanced dicing solution throughout the entire dicing operation. This continuous application of the protective solution ensures that corrosion inhibition and contaminant prevention are maintained throughout the extended processing time.
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 effectively prevents the adherence of silicon residues and particles, reduces corrosion, and improves the cleaning efficiency, as demonstrated by microscopy and SEM images, even when diluted, thereby enhancing the reliability of the wafer dicing process.
Implementation Method 1
a surfactant selected from the group consisting of phosphate esters, branched alcohol ethoxylate based surfactant; alkyldiphenyloxide disulfonic acid based surfactant
Implementation Method 2
at least one dicarboxylic acid and/or salt thereof; at least one hydroxycarboxylic acid and/or salt thereof or amine group containing acid; wherein the dicing solution is fluoride-free and having a pH of about 1 to about 4
Data Source
AI summary
Adherence of contaminant residues or particles is suppressed, corrosion of exposed surfaces is substantially reduced or eliminated during the process of dicing a wafer by sawing. A fluoride-free aqueous composition comprising a dicarboxylic acid and/or salt thereof; a hydroxycarboxylic acid and/or salt thereof or amine group containing acid, a surfactant and deionized water is employed.