Etching Agent for Titanium-Based Metal on Semiconductor Substrate
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Solution Overview
Problem
Conventional etching solutions for titanium-based metals on semiconductor substrates with copper or copper alloys face issues of short solution life-time due to hydrogen peroxide decomposition, requiring precise control of hydrogen peroxide concentration and leading to copper oxide corrosion.
Innovation Solution
An etching agent comprising an aqueous solution with hydrogen peroxide, a phosphonic acid-based chelating agent having a nitrogen atom, alkali metal hydroxide, and an organic acid with at least one hydroxyl group and three carboxyl groups, which suppresses hydrogen peroxide decomposition and reduces copper oxide elution, thereby stabilizing the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an etching solution containing hydrogen peroxide is used to etch titanium-based metals, then etching capability is improved, but solution life-time becomes short due to decomposition
Solution Approach 1:
A copper corrosion inhibitor is introduced as an intermediary substance that mediates between hydrogen peroxide and copper. The inhibitor preferentially binds to copper ions, preventing catalytic decomposition of hydrogen peroxide by copper while allowing the etching solution to maintain its effectiveness for titanium-based metals throughout the entire copper wiring layer formation process.
2Productivity
If hydrogen peroxide concentration is increased to maintain etching effectiveness, then etching rate is improved, but copper wiring corrosion increases
Solution Approach 1:
The invention changes the chemical parameter composition of the etching solution by adding a copper corrosion inhibitor. This allows the use of higher hydrogen peroxide concentrations for maintaining etching rate while the inhibitor simultaneously suppresses copper wiring corrosion through preferential binding to copper ions, thus resolving the contradiction between etching effectiveness and copper protection.
3Manufacturing precision
If conventional etching solutions are used for cleaning processes, then titanium etching is achieved, but copper oxide corrosion occurs
Solution Approach 1:
The copper corrosion inhibitor acts as a protective intermediary during the cleaning process. It selectively binds to copper surfaces and copper ions, forming a protective complex that prevents copper oxide formation and corrosion, while allowing the etching solution to effectively remove titanium-based metals from the semiconductor substrate without harmful side effects on copper wiring.
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 etching agent extends solution life-time, maintains stable etching rates, and reduces the need for hydrogen peroxide concentration control, ensuring effective etching of titanium-based metals without significant copper alloy etching.
Implementation Method 1
an etching solution composed of specific amount of hydrogen peroxide and specific amount of phosphoric acid
Implementation Method 2
an etching agent composed of a solution containing hydrogen peroxide and a chelating agent
Data Source
AI summary
The object of the present invention is to provide: an etching agent for a titanium-based metal on a semiconductor substrate, which suppresses decomposition of hydrogen peroxide, has a long liquid service life, and has less need for controlling the concentration of hydrogen peroxide in the etching agent, even in the cases where the etching agent is used for a semiconductor substrate having the titanium-based metal and a metallic copper or a metal alloy; an etching method; and an etching agent preparation liquid for use by mixing with hydrogen peroxide.The present invention relates to: an etching agent for a titanium-based metal on a semiconductor substrate, having a titanium-based metal and a metallic copper or a copper alloy on the upper part of the titanium-based metal, comprising an aqueous solution containing at least (A) hydrogen peroxide, (B) phosphonic acid-based chelating agent having a nitrogen atom in the structure, (C) alkali metal hydroxide, and (D) organic acid having at least one hydroxyl group and at least three carboxyl groups; an etching method, which comprises using the etching agent; and an etching agent preparation liquid for use by mixing with hydrogen peroxide.