Etching Composition for Selective Titanium Nitride Removal
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in achieving high etch-selectivity and efficient etching of metal layers, particularly in removing impurities and maintaining the integrity of conductive lines, due to limitations in existing cleaning solutions which often result in reduced cross-sectional area and increased resistance.
Innovation Solution
An etching composition comprising hydrogen peroxide, phosphoric acid, an amine or amide polymer, and deionized water, specifically formulated to etch titanium or titanium nitride layers at a higher rate than tungsten layers, with a ratio of 10:1 or more, ensuring high etch-selectivity and effective cleaning while preventing resistance increases in semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning solutions are used, then the etching process can be performed, but the etch-selectivity between titanium nitride and tungsten layers is insufficient
Solution Approach 1:
The patent modifies the chemical composition parameters of the cleaning solution by incorporating specific concentrations of hydrogen peroxide (1-7 wt%), phosphoric acid (20-80 wt%), and sulfuric acid (0-55 wt%), along with amine or amide polymers (0.001-1 wt%). These parameter changes create a chemically selective environment that etches titanium nitride at least 10 times faster than tungsten, achieving the required etch-selectivity while preserving tungsten conductive line integrity
Solution Approach 2:
The cleaning solution employs a composite chemical formulation combining multiple acids (hydrogen peroxide, phosphoric acid, sulfuric acid) with amine or amide polymers. This composite composition creates synergistic chemical reactions that selectively target titanium nitride while being substantially inert to tungsten, thereby resolving the contradiction between achieving high etch-selectivity and maintaining tungsten layer integrity
2Productivity
If the etching rate of titanium nitride is increased, then the cleaning efficiency is improved, but the risk of damaging tungsten layers increases
Solution Approach 1:
The amine or amide polymers in the cleaning solution act as intermediary substances that facilitate selective chemical reactions. These polymers enhance the etching activity toward titanium nitride through complexation and catalytic effects while simultaneously providing protective interactions with tungsten surfaces, preventing excessive etching or damage to the tungsten conductive lines even at high etching rates
Solution Approach 2:
By carefully controlling the concentration parameters of each chemical component—particularly the amine/amide polymer content (0.001-1 wt%) and acid ratios—the cleaning solution achieves optimal etching kinetics that favor titanium nitride removal (etch rate ≥100 Å/min) while maintaining selective inhibition of tungsten etching, thus improving productivity without causing harmful effects to tungsten layers
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 composition effectively maintains high etch-selectivity, ensuring efficient removal of impurities and minimizing resistance increases in semiconductor devices, thereby enhancing the reliability and performance of semiconductor devices by maintaining the integrity of conductive lines.
Implementation Method 1
The etching composition includes about 1 wt % to about 7 wt % of hydrogen peroxide
Implementation Method 2
The etching composition includes about 20 wt % to about 80 wt % of phosphoric acid
Implementation Method 3
The etching composition includes about 0.001 wt % to about 1 wt % of an amine or amide polymer
Data Source
AI summary
An etching composition includes about 1 wt % to about 7 wt % of hydrogen peroxide, about 20 wt % to about 80 wt % of phosphoric acid, about 0.001 wt % to about 1 wt % of an amine or amide polymer, 0 wt % to about 55 wt % of sulfuric acid, and about 10 wt % to about 45 wt % of deionized water.