Oxygen-Free Ruthenium Etching for Low-k Dielectric Selectivity
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Solution Overview
Problem
Conventional plasma etching processes for ruthenium (Ru) are not selective enough for low-k dielectric materials and often damage them due to the use of oxygen species and plasma, limiting the miniaturization of semiconductor devices.
Innovation Solution
An oxygen-free and plasma-free etching method using a halogen-containing vapor and a ligand-exchange agent to convert ruthenium metal into a volatile etch product, allowing for selective etching of ruthenium without damaging low-k dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching processes are used to etch ruthenium, then etching capability is achieved, but selectivity to low-k dielectric materials deteriorates and damage occurs
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using oxygen-free conditions and specific halogen-containing vapors (CF4, SF6, NF3) with ligand-exchange agents. This transforms the etching mechanism from plasma-based to vapor-phase chemical reaction, achieving both etching capability and improved selectivity to low-k dielectric materials
Solution Approach 2:
The patent employs an oxygen-free inert atmosphere during the etching process by using halogen-containing vapors in the absence of oxygen and plasma. This inert environment prevents damage to low-k dielectric materials while maintaining effective etching of ruthenium metal, thereby improving selectivity and reliability
2Productivity
If oxygen species and plasma are used in etching processes, then etching of ruthenium is achieved, but damage to low-k dielectric materials increases
Solution Approach 1:
The patent eliminates oxygen species and plasma by conducting the etching process in an oxygen-free vapor phase environment using halogen-containing gases (CF4, SF6, NF3). This inert atmosphere prevents harmful interactions with low-k dielectric materials while maintaining efficient ruthenium etching through ligand-exchange mechanisms
Solution Approach 2:
The patent replaces the plasma-based mechanical/physical etching mechanism with a chemical vapor phase process using halogen-containing vapors and ligand-exchange agents. This substitution eliminates the harmful effects of plasma and oxygen species on low-k dielectric materials while achieving effective etching through chemical reactions
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
This method enables the etching of ruthenium and other non-volatile metals with improved selectivity and reduced damage to low-k dielectric materials, facilitating the integration of new materials in semiconductor fabrication and enhancing the miniaturization of semiconductor devices.
Implementation Method 1
exposing the Ru metal layer of the substrate to a halogen-containing vapor, and to a ligand-exchange agent to form the volatile Ru etch product
Implementation Method 2
exposing the substrate to a ligand-exchange agent in the processing chamber, the ligand-exchange agent reacting with the intermediate to form volatile products
Data Source
AI summary
A method of processing a substrate that includes: forming an etch mask over a ruthenium (Ru) metal layer of a substrate, the etch mask exposing a first portion of the Ru metal layer and covering a second portion of the Ru metal layer; and converting the first portion of the Ru metal layer into a volatile Ru etch product in a processing chamber, the converting including exposing the Ru metal layer of the substrate to a halogen-containing vapor, and to a ligand-exchange agent to form the volatile Ru etch product, where the converting is an oxygen-free process.