Copper Etchant Composition for Selective Semiconductor Wiring Etching
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Solution Overview
Problem
Current etching techniques fail to selectively etch copper and copper alloys while suppressing the dissolution of nickel, nickel alloys, tin, tin alloys, gold, and gold alloys, particularly when these metals are used as wiring materials in semiconductor substrates with bumps like TSV in next-generation DRAM and NAND memories.
Innovation Solution
An etchant composition comprising 5-10.5% hydrogen peroxide, 0.3-6% nitric acid, a nitrogen-containing 5-membered ring compound such as triazoles or tetrazoles, and a pH adjuster like alkali metal hydroxide or phosphonic acid compounds is used to selectively etch copper and copper alloys, preventing the dissolution of nickel, tin, and gold alloys during the semiconductor substrate production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etchants (e.g., hydrogen peroxide and nitric acid) are used to etch copper and copper alloy, then copper etching capability is achieved, but dissolution of nickel, tin, and gold alloys cannot be prevented
Solution Approach 1:
The patent introduces a nitrogen-containing 5-membered ring compound (triazole or tetrazole derivative) as an intermediary substance that selectively adsorbs onto the surfaces of nickel, tin, and gold alloys, forming a protective layer that prevents these metals from dissolving in the etchant while allowing copper etching to proceed
Solution Approach 2:
The patent modifies the chemical composition parameters of the etchant by adding the nitrogen-containing 5-membered ring compound at specific concentrations (0.01-5 wt%), which changes the selective interaction properties of the etchant solution, enabling it to differentiate between copper (to be etched) and other metals (to be protected)
2Manufacturing precision
If an etchant is designed to suppress dissolution of multiple metals (nickel, tin, gold alloys), then selectivity is improved, but etching efficiency of copper may be reduced
Solution Approach 1:
The nitrogen-containing 5-membered ring compound exhibits local quality by selectively adsorbing only onto specific metal surfaces (nickel, tin, and gold alloys) while leaving copper surfaces exposed and reactive, thereby achieving local protection of certain metals while maintaining etching capability on copper
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 allows for the selective etching of copper and copper alloys while preventing the dissolution of nickel, tin, and gold alloys, making it suitable for wiring formation in semiconductor substrates with bumps, enhancing the production efficiency and quality of semiconductor substrates.
Implementation Method 1
an etchant for selectively etching at least one selected from the group consisting of copper and a copper alloy... comprising: (A) 5 to 10.5% by mass of hydrogen peroxide... (B) 0.3 to 6% by mass of nitric acid... (C) at least one nitrogen-containing 5-membered ring compound selected from the group consisting of triazoles and tetrazoles
Implementation Method 2
hydrogen peroxide and nitric acid... copper and a copper alloy can be selectively etched
Data Source
AI summary
An etchant capable of selectively etching copper and a copper alloy while suppressing dissolution of nickel, tin, gold, and an alloy thereof. The etchant contains: (A) 5-10.5% by mass of hydrogen peroxide with respect to the total mass of the etchant; (B) 0.3-6% by mass of nitric acid with respect to the total mass of the etchant; (C) at least one nitrogen-containing 5-membered ring compound selected from triazoles and tetrazoles, which may have at least one substituent selected from a C1-6 alkyl group, an amino group, and a substituted amino group having a substituent selected from a C1-6 alkyl group and a phenyl group; and (D) (d1) one or more pH adjusters selected from an alkali metal hydroxide, ammonia, an amine, and an ammonium salt, (d2) a phosphoric acid compound, or (d3) a combination of (d1) and (d2).