Polishing Agent for Thick Copper Films via Multi-Acid Composition
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Solution Overview
Problem
Conventional polishing agents for copper alloys are inadequate for high-performance microcircuit boards and Through Silicon Vias (TSVs), as they do not achieve sufficient polishing speeds for thick metal films, particularly those exceeding 5 μm in thickness.
Innovation Solution
A polishing agent composition containing an inorganic acid, amino acid, protective film-forming agent, abrasive, oxidizing agent, and organic acid, with a pH adjusted to 1.5-4, specifically using sulfuric acid, phosphoric acid, benzotriazole, colloidal silica, and hydrogen peroxide, which enhances polishing speed and surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polishing agents are used for copper alloy films, then the polishing process can be performed, but the polishing speed is insufficient for thick metal films (5 μm and greater)
Solution Approach 1:
The patent changes the chemical composition parameters of the polishing agent by incorporating specific organic acids (oxalic acid, malonic acid, or maleic acid) with controlled concentrations (0.01-5 wt%), along with amino acids, protective film-forming agents, and oxidizing agents. This chemical parameter optimization enables polishing speeds of 5 μm/min or more for thick copper films, resolving the contradiction between maintaining effectiveness across different film thicknesses and achieving high productivity.
2Productivity
If higher polishing speeds are achieved, then productivity improves, but surface roughness control becomes more difficult
Solution Approach 1:
The patent optimizes multiple chemical parameters simultaneously: organic acid concentration (0.01-5 wt%), amino acid concentration (0.1-10 wt%), protective film-forming agent concentration (0.01-5 wt%), and oxidizing agent concentration (0.1-10 wt%). This multi-parameter optimization achieves the dual goal of high polishing speed (≥5 μm/min) and controlled surface roughness (Ra ≤ 5 nm), resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent creates a composite polishing agent system combining multiple functional components: organic acids for chemical etching, amino acids for surface protection and complexation, protective film-forming agents for controlled removal, oxidizing agents for metal oxidation, and abrasives for mechanical polishing. This composite formulation enables simultaneous achievement of high polishing speed and smooth surface finish by coordinating multiple mechanisms.
3Productivity
If conventional polishing agents are used, then the process is simple, but rapid polishing treatment cannot be ensured for thick metal films
Solution Approach 1:
The patent modifies the chemical parameters of conventional polishing agents by adding specific organic acids (oxalic acid, malonic acid, or maleic acid) at controlled concentrations (0.01-5 wt%), along with amino acids, protective film-forming agents, and oxidizing agents. This parameter optimization achieves polishing speeds of 5 μm/min or more for thick copper films, resolving the contradiction between maintaining process simplicity and achieving high productivity.
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 polishing agent achieves a polishing speed of at least 4 μm/min with low surface roughness, optimizing productivity for high-performance circuit boards and TSVs by ensuring efficient removal of thick copper films.
Implementation Method 1
presumably the metal film surface is first oxidized by the oxidizing agent and the oxidation layer is shaved by the abrasive
Implementation Method 2
the oxidation layer is shaved by the abrasive, resulting in polishing of the metal film
Implementation Method 3
removing the metal film on the heights by mechanical friction between the polishing agent and the heights of the metal film
Implementation Method 4
a polishing agent which comprises a composition containing an inorganic acid, an amino acid, a protective film-forming agent, an abrasive, an oxidizing agent, an organic acid and water, adjusted to a pH of 1.5-4
Implementation Method 5
the amount of potassium hydroxide required to raise the pH of the composition without the organic acid to 4 is at least 0.10 mol with respect to 1 kg of the composition without the organic acid, the organic acid contains at least two carboxyl groups
Data Source
AI summary
A polishing agent which comprises a composition containing an inorganic acid, an amino acid, a protective film-forming agent, an abrasive, an oxidizing agent, an organic acid and water, adjusted to a pH of 1.5-4, wherein the amount of potassium hydroxide required to raise the pH of the composition without the organic acid to 4 is at least 0.10 mol with respect to 1 kg of the composition without the organic acid, and the organic acid contains at least two carboxyl groups, wherein the logarithm of the inverse of the first acid dissociation constant (pKa1) is no greater than 3.