Selective Copper Etching Using Hydrogen Peroxide and Citric Acid
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Solution Overview
Problem
Conventional semiconductor device manufacturing methods fail to selectively etch copper without etching nickel, leading to insufficient performance in downsized and high-integration semiconductor devices.
Innovation Solution
A method using an etchant containing hydrogen peroxide and a specified hydroxy acid, such as citric acid or malic acid, in specific compositions to selectively etch copper without etching nickel, ensuring stable etching rates and performances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etchants are used to etch copper, then copper etching is achieved, but nickel is also etched unintentionally
Solution Approach 1:
The patent modifies the chemical composition parameters of the etchant by incorporating specific organic acids (oxalic acid, malic acid, or citric acid) along with hydrogen peroxide and water. This parameter change enables selective etching of copper while preventing nickel etching, achieving the desired selectivity without harmful side effects.
Solution Approach 2:
The patent introduces organic acids as intermediary substances that mediate the etching process. These intermediaries selectively interact with copper to facilitate etching while being inert toward nickel, thus enabling precise control over which metal is etched and preventing unintentional nickel removal.
2Productivity
If conventional etching methods are used, then etching process is completed, but nickel layer integrity is compromised
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by formulating a specific composition containing organic acids and hydrogen peroxide. This modified composition maintains high etching efficiency for copper while ensuring nickel layer integrity, thus simultaneously achieving productivity and reliability.
Solution Approach 2:
The patent converts the potential harm of nickel etching into a benefit by using organic acids that selectively target copper. The etching process, which could potentially damage nickel, is transformed into a selective copper removal process that actually protects nickel layer integrity while maintaining efficient copper etching.
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 method allows for the selective etching of copper without damaging nickel, enhancing the performance of semiconductor devices by maintaining the integrity of nickel layers during the etching process, thus addressing the limitations of conventional methods.
Implementation Method 1
an etchant which contains hydrogen peroxide and, as an organic acid component, citric acid or malic acid that is a specified hydroxy acid and has a specified composition
Data Source
Figure 1A(a)~1A(h)
Figure 2A(i)~2A(p)
Figure 3B(a)~3B(g)
AI summary
Disclosed are an etchant which is used for redistribution of 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 which is used for redistribution of a semiconductor substrate and which contains hydrogen peroxide and citric acid and has a content of hydrogen peroxide of from 0.75 to 12 % by mass and a content of citric acid of from 1 to 20 % by mass, with a molar ratio of hydrogen peroxide and citric acid being in the range of from 0.3 to 5; an etchant for selective etching of copper which is used for redistribution of a semiconductor substrate and which contains hydrogen peroxide and malic acid and has a content of hydrogen peroxide of from 0.75 to 12 % by mass and a content of malic acid of from 1.5 to 25 % by mass, with a molar ratio of hydrogen peroxide and malic acid being in the range of from 0.2 to 6; and a method for manufacturing a semiconductor device using such an etchant.