Ruthenium Etching Chemistry with pH Control to Suppress RuO4
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Solution Overview
Problem
The existing ruthenium etching solutions for semiconductor manufacturing have a low etching rate, leading to prolonged processing times, and there is a risk of producing toxic ruthenium tetroxide when used with ruthenium-containing materials.
Innovation Solution
A ruthenium-etching solution comprising orthoperiodic acid and ammonia, with a pH adjusted to 8 or higher and 10 or lower, is developed to enhance the etching rate while minimizing the production of ruthenium tetroxide, including a method for manufacturing and using this solution for processing ruthenium-containing substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing ruthenium etching solutions are used, then the etching process can be performed, but the etching rate is excessively small causing prolonged processing time
Solution Approach 1:
The patent changes the pH parameter of the etching solution to 8 or higher and 10 or lower, which fundamentally alters the etching kinetics. This parameter change enables the etching rate to reach 1 nm/min or more while maintaining solution stability, directly resolving the contradiction between achieving practical productivity and avoiding excessive processing time
Solution Approach 2:
The patent creates a composite etching solution system combining orthoperiodic acid (oxidizing agent) with ammonia (pH regulator). This composite formulation synergistically achieves both high etching rate and controlled processing time, as the ammonia component modulates the solution's reactivity while the orthoperiodic acid provides the etching capability
2Productivity
If existing ruthenium etching solutions are used, then etching can proceed, but toxic ruthenium tetroxide may be produced by contact between the etching solution and ruthenium
Solution Approach 1:
By adjusting the pH parameter to 8 or higher and 10 or lower, the patent transforms the chemical environment to suppress ruthenium tetroxide formation. This parameter change maintains etching capability through controlled oxidation while preventing the harmful side reaction that produces volatile and toxic ruthenium tetroxide
Solution Approach 2:
The patent converts the potentially harmful interaction between oxidizing agents and ruthenium (which could produce toxic RuO4) into a beneficial controlled etching process. By using ammonia to moderate the oxidation potential, the solution achieves effective ruthenium removal while converting the harmful uncontrolled oxidation into a safe and controllable etching reaction
3Productivity
If the etching rate is increased to reduce processing time, then productivity improves, but the risk of ruthenium tetroxide generation increases
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: pH (8-10) controls both etching rate and RuO4 formation, while the combination of orthoperiodic acid concentration and ammonia concentration creates a chemical environment that achieves high etching rates (≥1 nm/min) while suppressing harmful byproduct generation through balanced redox chemistry
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 solution achieves a practical etching rate for ruthenium with reduced risk of ruthenium tetroxide generation, enabling efficient and safe processing of ruthenium-containing layers and wiring.
Implementation Method 1
a solution including orthoperiodic acid as an oxidizing agent has been proposed
Implementation Method 2
including orthoperiodic acid and ammonia, in which a pH is 8 or higher and 10 or lower
Data Source
AI summary
A ruthenium-etching solution for carrying out an etching process on ruthenium. The etching solution includes orthoperiodic acid and ammonia, in which a pH is 8 or higher and 10 or lower. A method for manufacturing the ruthenium-etching solution, a method for processing an object to be processed including carrying out an etching process on an object to be processed including ruthenium using the ruthenium-etching solution, and a method for manufacturing a ruthenium-containing wiring.