Copper Etchant with Aromatic Additives for Continuous Stability
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Solution Overview
Problem
Existing copper etchants, particularly sulfuric acid hydrogen peroxide-based etchants, struggle to maintain the smoothness of copper surfaces after etching, especially when continuous etching treatments are performed, leading to unstable etching performance and potential deterioration of wiring shape and characteristics.
Innovation Solution
A copper etchant formulation comprising hydrogen peroxide, sulfuric acid, an aromatic compound with a hydroxyl group and/or carboxy group bonded to a benzene ring, and a controlled concentration of chlorine ions, along with optional triazoles, to stabilize the etching process and maintain surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sulfuric acid hydrogen peroxide-based etchant is used, then copper seed layer can be removed, but smoothness of copper surface deteriorates and becomes unstable during continuous etching
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by introducing specific organic compounds (benzotriazole, amine, amino acid, nitrogen-containing heterocyclic compound) in controlled concentrations alongside sulfuric acid and hydrogen peroxide. This composition modification alters the etching mechanism to achieve stable smoothness maintenance during continuous processing
Solution Approach 2:
The etching solution employs a composite chemical system combining inorganic etchants (sulfuric acid, hydrogen peroxide) with multiple organic additives that work synergistically. The benzotriazole compound suppresses copper dissolution, while amino acids and nitrogen-containing compounds provide surface protection, creating a composite etchant that maintains stable smoothness
2Productivity
If conventional etchant composition is used, then etching process can proceed, but undercut of copper wiring occurs
Solution Approach 1:
The etching solution exhibits local quality control by selectively protecting copper wiring regions through adsorption of benzotriazole and amino acid compounds on copper surfaces. This creates a protective layer that prevents undercut while allowing etching to proceed in non-wiring areas, maintaining wiring shape integrity
Solution Approach 2:
The organic compounds (benzotriazole, amine, amino acid) act as intermediary substances that mediate between the aggressive sulfuric acid-hydrogen peroxide system and the copper wiring. These intermediaries adsorb on copper surfaces to form protective films, preventing direct attack by the etchant and thus preventing undercut while maintaining etching efficiency
3Quantity of substance
If sulfuric acid and hydrogen peroxide are used as etchant components, then copper etching can be achieved, but smoothness of copper surface cannot be stably maintained
Solution Approach 1:
The patent converts the harmful aggressive etching action of sulfuric acid and hydrogen peroxide into a beneficial controlled process by adding benzotriazole and amino acid compounds. These additives initially seem to slow etching but actually enable stable smoothness maintenance by controlling the etching mechanism and preventing surface roughening
Solution Approach 2:
The patent modifies the chemical parameters by introducing organic compounds that change the etching mechanism from aggressive dissolution to controlled removal. The benzotriazole compound concentration (0.001-10 g/L) and amino acid concentration (0.1-10 g/L) are optimized to maintain smoothness while preserving adequate etching capability
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 etchant effectively maintains a highly smooth copper surface with reduced side etching, even under continuous etching conditions, ensuring stable etching performance and suitable wiring formation.
Implementation Method 1
hydrogen peroxide acts as an oxidant for copper
Implementation Method 2
sulfuric acid acts as a component that dissolves copper oxidized in the etchant
Data Source
Figure 1~2
Figure 3
AI summary
A problem is to provide a copper etchant capable of stably maintaining smoothness after etching. As means for solving the problem, the etchant contains hydrogen peroxide, sulfuric acid, an aromatic compound, and a chlorine ion, in which the aromatic compound has a structure in which a hydroxyl group and/or a carboxy group is bonded to a benzene ring.