Ruthenium Wafer Etching Solution for Flat Surfaces and Lower RuO4
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching liquids for ruthenium on semiconductor wafers fail to maintain the flatness of the ruthenium surface after etching, and they do not effectively inhibit the generation of RuO4 gas, which is harmful and reduces yield in semiconductor formation.
Innovation Solution
A treatment liquid containing hypochlorite ions and a specific alkylammonium salt is used for wet etching of ruthenium. The alkylammonium salt forms a protective layer on the ruthenium surface, preventing excessive oxidation and maintaining surface flatness, while also inhibiting the generation of RuO4 gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching liquids (halogen oxoates, orthoperiodic acid, or standard alkaline solutions) are used to remove ruthenium, then the etching rate is sufficient, but the flatness of the ruthenium surface deteriorates and RuO4 gas is generated
Solution Approach 1:
The patent introduces an amine compound as an intermediary substance that mediates between the alkaline etching environment and the ruthenium surface. The amine compound adsorbs onto the ruthenium surface and moderates the etching reaction, preventing excessive oxidation while maintaining adequate etching rate. This intermediary layer protects the surface flatness while allowing controlled material removal.
Solution Approach 2:
The patent modifies the chemical parameters of the etching solution by adding amine compounds with specific molecular weights and functional groups to standard alkaline solutions. This parameter change transforms the aggressive etching chemistry into a more controlled process that maintains surface flatness. The amine compound concentration and molecular weight are optimized to achieve the desired balance between etching rate and surface quality.
2Productivity
If strong oxidizing agents are used to ensure complete ruthenium removal, then etching effectiveness improves, but harmful RuO4 gas generation increases
Solution Approach 1:
The patent converts the harmful strong oxidizing environment into a beneficial controlled etching process by introducing amine compounds. The amine compounds react with excess oxidizing agents to form less harmful species while maintaining the etching effectiveness. This transforms the harmful RuO4 gas-generating oxidation into a controlled reaction that produces desirable etching results without excessive gas generation.
Solution Approach 2:
The amine compound acts as a mediator that controls the oxidation process. It allows sufficient oxidation for effective etching while preventing the formation of RuO4 gas by providing an alternative reaction pathway. The amine compound intermediates the oxidation reaction, ensuring complete ruthenium removal without generating harmful gases.
3Manufacturing precision
If precise etching control is implemented to maintain surface flatness, then manufacturing precision improves, but process complexity increases
Solution Approach 1:
The patent simplifies the control mechanism by changing the chemical composition parameters of the etching solution rather than implementing complex process control systems. By optimizing the amine compound concentration, molecular weight, and functional groups, the patent achieves precise etching control through formulation rather than complex process parameters, reducing overall process complexity.
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 treatment liquid achieves a high etching rate of 20 Å/min or more for ruthenium while maintaining the flatness of the ruthenium surface, making it suitable for semiconductor element formation with multilayer wiring structures. Additionally, it effectively inhibits the generation of RuO4 gas, improving yield and safety.
Implementation Method 1
The alkylammonium salt forms a protective layer on the ruthenium surface, preventing excessive oxidation and maintaining surface flatness
Implementation Method 2
In cases where ruthenium is subjected to wet etching under alkaline conditions, ruthenium is dissolved, for example, in the form of RuO4
Data Source
Figure 1~2
Figure 3
AI summary
Provided is a treatment liquid for a semiconductor wafer or the like used in a process for forming a semiconductor. Namely a treatment liquid containing (A) a hypochlorite ion, and (B) an alkylammonium salt expressed by the following Formula (1), or the like is provided. (In the Formula, "a" is an integer from 6 to 20; R1, R2, and R3 are independently, for example, an alkyl group with a carbon number from 1 to 20; and X- is, for example, a chloride ion.)