Ruthenium Etching Solution for Low Surface Roughness
Solution Overview
Problem
Current chemical solutions for etching ruthenium-containing layers in semiconductor fabrication face challenges in maintaining a good etching rate while reducing surface roughness and preventing intergranular corrosion.
Innovation Solution
A chemical solution comprising orthoperiodic acid, a base component, and a nitrogen-containing heterocyclic compound, organic phosphonic acid, or organic carboxylic acid is used to etch ruthenium-containing layers, effectively reducing surface roughness and maintaining a high etching rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an etching solution containing orthoperiodic acid with pH of 8 or more is used to etch ruthenium, then the etching rate is improved, but intergranular corrosion occurs and surface roughness increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the etching solution by adding specific organic compounds (nitrogen-containing heterocyclic compounds, organic phosphonic acids, or organic carboxylic acids) to the orthoperiodic acid-based solution. This parameter change allows the solution to maintain high etching rate while suppressing intergranular corrosion and reducing surface roughness, resolving the contradiction between productivity and manufacturing precision.
2Ease of manufacture
If dry etching is performed on ruthenium layer, then the Semi-Damascene structure can be formed, but ruthenium residue forms on the surface requiring additional cleaning
Solution Approach 1:
The chemical solution of the patent serves multiple functions: it acts as both an etching solution for forming the Semi-Damascene structure and as a cleaning solution for removing ruthenium residue. This multi-functionality eliminates the need for separate cleaning processes while maintaining the benefits of dry etching, resolving the contradiction between ease of manufacture and harmful residue generation.
3Length of moving object
If pattern miniaturization is pursued in wiring, then lithography capability is improved, but alignment margins decrease causing resistance fluctuation
Solution Approach 1:
The patent employs Fully Self Aligned Via (FSAV) technology where the via holes are automatically aligned with the wiring patterns through selective etching of recesses. The chemical solution enables precise control of the recess formation process, allowing the structure to self-align without additional alignment margins. This self-service mechanism resolves the contradiction between pattern miniaturization and alignment reliability.
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 reduced surface roughness and sustained etching efficiency, improving the reliability of ruthenium wiring fabrication by minimizing intergranular corrosion and maintaining consistent etching performance.
Implementation Method 1
an etching method using an etching solution, which contains orthoperiodic acid as an oxidant
Data Source
AI summary
A chemical solution used for cleaning or etching a ruthenium-containing layer, which can obtain the ruthenium-containing layer having a reduced surface roughness while maintaining a good etching rate against the ruthenium, and a method for fabricating ruthenium wiring. The chemical solution includes orthoperiodic acid, a base component, and any one of a nitrogen-containing heterocyclic compound, an organic phosphonic acid, and an organic carboxylic acid.