Copper Polishing Solution for TSV and Microcircuit Flatness
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Solution Overview
Problem
Conventional polishing solutions for copper alloys in microelectronic manufacturing result in low polishing rates and reduced productivity, particularly for thick metal films, leading to impaired wiring resistance and surface flatness issues due to high copper elution rates and pad staining, which affects the quality of high-performance microcircuit boards and Through Silicon Via (TSV) production.
Innovation Solution
A polishing solution comprising specific organic acids, inorganic acids, amino acids, a protective film-forming agent, abrasive grains, and an oxidizing agent, with controlled component ratios and concentrations, minimizes pad staining and enhances polishing rates and flatness by forming a reaction layer that is more easily removable, thereby improving the polishing process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing solutions are used for thick metal films, then polishing can be performed, but the polishing rate is low and productivity is reduced
Solution Approach 1:
The patent modifies the chemical composition parameters of the polishing solution by incorporating specific organic acids (formic acid, acetic acid, propionic acid, or butyric acid) at controlled concentrations (0.1-5.0 wt%), along with specific inorganic acids and amino acids. These parameter changes in the solution chemistry enable significantly higher polishing rates for thick copper alloy films while maintaining solution stability and preventing excessive copper elution.
2Manufacturing precision
If conventional polishing solutions are used, then polishing can be performed, but pad staining occurs and flatness is reduced
Solution Approach 1:
The patent introduces amino acids (glycine, alanine, valine, leucine, isoleucine, serine, threonine, cysteine, cystine, methionine, aspartic acid, glutamic acid, lysine, arginine, phenylalanine, tyrosine, histidine, tryptophan, proline, oxyproline, asparagine, or glutamine) as intermediary substances that mediate between the copper alloy film and the polishing solution. These amino acids form stable complexes with copper ions, preventing excessive copper elution and pad staining while maintaining controlled material removal for achieving flat surfaces.
3Reliability
If conventional polishing solutions are used, then polishing can be performed, but copper elution rate is high which impairs wiring resistance
Solution Approach 1:
The patent converts the potentially harmful high copper elution rate into a beneficial process by carefully controlling the concentration of organic acids and adding amino acids that form stable copper complexes. The organic acids provide controlled etching action while the amino acids capture copper ions in solution, preventing excessive copper loss from the film while still enabling effective material removal for polishing.
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 achieves significantly higher polishing rates, up to 30000 Å/min, while maintaining stable productivity and surface flatness, even for thick metal films, reducing pad staining and ensuring high-quality finishes for microcircuit boards and TSVs.
Implementation Method 1
the metal film surface is oxidized by the oxidizing agent to form an oxidation layer
Implementation Method 2
the metal film is polished by shaving the oxidation layer with the abrasive grain
Implementation Method 3
removing the metal film on the elevated sections by mechanical friction between the polishing solution and the metal film on the elevated sections
Data Source
AI summary
The polishing solution for copper polishing of the invention comprises a first organic acid component which is at least one type selected from among an organic acid containing a hydroxyl group, an organic acid salt and an organic acid anhydride, an inorganic acid component which is at least one type selected from among a dibasic or greater inorganic acid and an inorganic acid salt, an amino acid, a protective film-forming agent, an abrasive grain, an oxidizing agent and water, wherein the inorganic acid component content in terms of inorganic acid is 0.15 mass % or greater, the amino acid content is 0.30 mass % or greater, the protective film-forming agent content is 0.10 mass % or greater, based on the entire polishing solution for copper polishing, and the ratio of the first organic acid component content in terms of organic acid with respect to the protective film-forming agent content is at least 1.5.