Metal Etching Liquid Chemistry for Narrow Trench TiN Shaping
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Solution Overview
Problem
The challenge lies in achieving an efficient etching process for substrates with narrow trench structures, where the etchant struggles to infiltrate and maintain an excellent etching rate due to the narrow spaces, particularly in FinFET manufacturing where TiN layers require precise shaping.
Innovation Solution
A substrate processing liquid containing H2O2 molecules or HO2− as an etchant and a complex forming agent with NH4+ ions, adjusted to a pH of 5 or more, is used to enhance etchant infiltration and etching efficiency by forming complexes with metal ions, thereby improving the etching rate and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching liquids are used, then the etching process can be applied to substrates, but the etchant cannot efficiently infiltrate narrow trench structures, resulting in reduced etching rate
Solution Approach 1:
The patent changes the chemical parameters of the etching liquid by adjusting pH to 5 or more and adding complex forming agents containing NH4+. These parameter changes enable the etchant to effectively infiltrate narrow trench structures while maintaining high etching rates, resolving the contradiction between infiltration efficiency and etching productivity
Solution Approach 2:
The complex forming agent acts as an intermediary substance that facilitates the interaction between the etchant and metal ions in the trench structure. By forming complexes with metal ions, it enhances etchant penetration into narrow spaces while maintaining effective etching, thus resolving the infiltration-etching rate contradiction
2Manufacturing precision
If the fin pitch is reduced to achieve finer patterns, then the pattern resolution is improved, but the trench openings become narrower making etchant infiltration difficult
Solution Approach 1:
By adjusting the pH parameter to 5 or more and introducing complex forming agents, the patent enables effective etching in increasingly narrow trench structures. This allows continuous reduction of fin pitch for finer patterns while maintaining adequate etchant infiltration through modified chemical parameters
3Quantity of substance
If the trench structure becomes narrower, then the pattern density is increased, but the etching rate is reduced due to poor etchant infiltration
Solution Approach 1:
The patent modifies the chemical parameters of the etching liquid (pH adjustment to 5 or more, addition of complex forming agents) to maintain high etching rates even in narrow trench structures with high pattern density, thus resolving the contradiction between quantity of pattern and etching productivity
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
This approach allows for an excellent etching rate and precise shaping of metal layers in FinFETs, ensuring high-performance device manufacturing by efficiently infiltrating the etchant into narrow trench structures and maintaining selectivity.
Implementation Method 1
a chemical liquid containing H2O2 molecules or HO2− functioning as an etchant for etching the metal
Implementation Method 2
a complex forming agent containing NH4+ and forming a complex with ions of the metal
Data Source
AI summary
A substrate processing liquid is used to etch a substrate in which at least either a bottom wall or a side wall forming a trench structure is an etched layer made of metal or a metal compound. The substrate processing liquid includes a chemical liquid containing H2O2 molecules or HO2− functioning as an etchant for etching the metal, and a complex forming agent containing NH4+ and forming a complex with ions of the metal and is adjusted to a pH of 5 or more.