Ruthenium Removal Composition for MRAM Etch Residue Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods face challenges in accurately removing ruthenium residues from semiconductor substrates during dry etching while preventing damage to cobalt iron boron (CoFeB) and magnesium oxide (MgO) layers, which are crucial for maintaining the integrity of semiconductor devices as they become increasingly complex.
Innovation Solution
A ruthenium removal composition comprising orthoperiodic acid and water with a pH of 11 or more, along with a pH adjusting agent like tetramethylammonium hydroxide or monoethanolamine, effectively dissolves ruthenium residues while minimizing the dissolution of CoFeB and MgO, ensuring the semiconductor substrate's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dry etching is used to process ruthenium, then ruthenium residues remain on the substrate, but increasing etching aggressiveness damages CoFeB and MgO layers
Solution Approach 1:
The invention changes the chemical parameters of the removal composition by using orthoperiodic acid as the active ingredient and adjusting the pH to 11 or more with pH adjusting agents. This specific parameter combination enables selective removal of ruthenium residues while suppressing dissolution of CoFeB and MgO layers, resolving the contradiction between removal efficiency and layer protection
Solution Approach 2:
The orthoperiodic acid acts as an intermediary chemical that selectively reacts with ruthenium residues without significantly affecting CoFeB and MgO layers. The high pH environment serves as a mediator that enhances the selectivity of the removal process, allowing effective residue removal while protecting the underlying layers
2Speed
If stronger removing agents are used to dissolve ruthenium residues, then dissolution rate increases, but CoFeB and MgO layers are also corroded
Solution Approach 1:
The invention achieves high dissolution rate of ruthenium while maintaining layer integrity by precisely controlling the chemical parameters: using orthoperiodic acid at controlled concentrations and maintaining pH at 11 or more. This parameter optimization creates a window where ruthenium dissolves rapidly but CoFeB and MgO remain stable
Solution Approach 2:
The removal composition exhibits local quality in its chemical reactivity: it is highly effective against ruthenium residues while being relatively inert toward CoFeB and MgO layers. This selective reactivity allows the same composition to perform different functions (rapid ruthenium dissolution vs. layer protection) simultaneously
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 composition enables efficient removal of ruthenium residues with controlled dissolution rates, protecting the CoFeB and MgO layers, thus supporting the production of magnetoresistive random access memory (MRAM) without damaging the substrate.
Implementation Method 1
A ruthenium removal composition including: orthoperiodic acid; and water, in which the pH is 11 or more
Data Source
AI summary
A treatment liquid contains orthoperiodic acid and water, and the pH is 11 or more. It is preferable that the content of orthoperiodic acid in the treatment liquid is 0.01% to 5% by mass with respect to the total mass of the treatment liquid.