Selective Copper Etching Etchant for Semiconductor Devices
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods fail to selectively etch copper without etching nickel, leading to reduced performance and oxidation of bump electrodes, particularly in high-integration and downsized devices.
Innovation Solution
An etchant comprising hydrogen peroxide, an organic acid (such as citric or malic acid), and an organic phosphonic acid is used, with specific mass content ratios to selectively etch copper while preventing nickel etching and oxidation of bump electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etchants are used to etch copper wiring, then copper etching is achieved, but nickel wiring is also etched unintentionally
Solution Approach 1:
The patent modifies the chemical composition parameters of the etchant by incorporating specific organic acids (oxalic acid at 0.1-5% by weight, citric acid at 0.1-5% by weight) combined with hydrogen peroxide and chelating agents. This parameter change enables selective etching of copper while suppressing nickel etching, achieving the desired selectivity without compromising nickel wiring integrity
Solution Approach 2:
The patent creates a composite etchant formulation combining multiple chemical components: hydrogen peroxide (oxidizing agent), organic acids (oxalic acid, citric acid), chelating agents (EDTA, DTPA), and buffering agents. This composite composition works synergistically to achieve selective copper etching while protecting nickel, resolving the contradiction between copper etching effectiveness and nickel wiring preservation
2Productivity
If conventional etching processes are used, then copper wiring is etched, but bump electrodes undergo oxidation leading to performance reduction
Solution Approach 1:
The patent introduces organic acids (oxalic acid, citric acid) and chelating agents as intermediary substances that mediate between the oxidizing hydrogen peroxide and the metal surfaces. These intermediaries control the oxidation process to etch copper selectively while preventing harmful oxidation of the bump electrode, thus maintaining electrode performance during efficient etching
Solution Approach 2:
The patent adjusts the concentration parameters of oxidizing agents (hydrogen peroxide at 1-30% by weight) and protective agents (organic acids and chelating agents) to optimize the etching process. By carefully controlling these parameters, the process achieves high etching efficiency while minimizing oxidation damage to bump electrodes
3Adaptability or versatility
If high integration and downsizing are implemented, then device functionality is enhanced, but selective etching becomes more difficult to achieve
Solution Approach 1:
The patent optimizes the chemical parameters of the etchant including pH control (using buffering agents like ammonia or ammonium fluoride), temperature control (20-80°C), and concentration ratios of active ingredients. These parameter adjustments enable precise control of etching selectivity required for high-integration devices with closely spaced copper and nickel interconnects
Solution Approach 2:
The patent develops a multi-component composite etchant formulation that combines oxidizing agents, organic acids, chelating agents, and buffering agents. This composite material provides the chemical complexity needed to achieve selective etching in high-integration devices where multiple metal layers with different etch resistances are present in close proximity
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 achieves selective copper etching without nickel etching, maintaining the performance and preventing oxidation of bump electrodes, especially in solder-based electrodes, thereby enhancing the manufacturing process for semiconductor devices.
Implementation Method 1
an etchant which is used in the subject step is not sufficiently reviewed, and in etching the member such as the wiring composed of copper, or the like, even the member composed of nickel is etched, too. Also, it is highly expected that the bump electrode is oxidized, whereby its performances are reduced.
Data Source
Figure 1A~1A(g)
Figure 2A~2A(l)
Figure 3B~3B(h)
AI summary
Disclosed are an etchant which is used for the manufacture of a semiconductor device using a semiconductor substrate having an electrode and which is capable of selectively etching copper without etching nickel, and a method for manufacturing a semiconductor device using the same. Specifically disclosed are an etchant to be used for the manufacture of a semiconductor device using a semiconductor substrate having an electrode, including hydrogen peroxide, an organic acid, and an organic phosphonic acid, wherein the organic acid is at least one member selected from citric acid and malic acid; a content of hydrogen peroxide is from 0.75 to 12% by mass; a content of the organic acid is from 0.75 to 25% by mass; and a content of the organic phosphonic acid is from 0.0005 to 1% by mass, and a method for manufacturing a semiconductor device using the etchant.