Selective Metal Nitride Removal via Ozone Oxidation
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Solution Overview
Problem
Conventional dry etch processes have low selectivity between tungsten and silicon nitride materials, leading to poor isolation of tungsten plugs and downstream process implications, while conventional wet etch solutions lack sufficient selectivity between tungsten and titanium/titanium nitride materials, resulting in incomplete removal of metal nitride materials during semiconductor fabrication.
Innovation Solution
An oxidizing solution comprising ozone and an additive, such as hydrogen fluoride, is used to selectively remove metal nitride materials from semiconductor device structures, achieving an etch rate at least two times greater than that of the metal materials, thereby allowing for precise removal of metal nitride materials without substantially affecting the metal materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dry etch processes are used to remove tungsten and titanium/titanium nitride materials, then the materials can be removed, but selectivity between tungsten and silicon nitride is low leading to poor isolation of tungsten plugs
Solution Approach 1:
The patent changes the chemical parameters of the etch solution by using an oxidizing solution containing ozone and hydrogen fluoride, which fundamentally alters the etching mechanism to achieve high selectivity between titanium nitride and tungsten, resolving the selectivity issue of conventional dry etch processes
Solution Approach 2:
The patent employs strong oxidants (ozone and hydrogen fluoride) to selectively oxidize and remove titanium nitride material while leaving tungsten intact, enabling precise isolation of tungsten plugs with high selectivity and preventing shorts
2Manufacturing precision
If conventional wet etch solutions are used to remove titanium/titanium nitride material, then the etching process can proceed, but selectivity between tungsten and titanium/titanium nitride is minimal resulting in complete removal of tungsten material
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing ozone and hydrogen fluoride into the wet etch solution, creating a selective etching environment that targets titanium nitride while preserving tungsten, thus achieving the desired selectivity without losing tungsten material
Solution Approach 2:
The oxidizing solution acts as an intermediary that selectively interacts with titanium nitride material, facilitating its removal while leaving tungsten unaffected, thereby achieving precise selectivity between the two materials
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 enables efficient and selective removal of metal nitride materials, improving the isolation of tungsten plugs and reducing the risk of shorts, while maintaining low costs and high efficiency in semiconductor fabrication processes.
Implementation Method 1
An oxidizing solution comprising ozone and an additive, such as hydrogen fluoride, is used to selectively remove metal nitride materials from semiconductor device structures
Data Source
AI summary
A method of removing a metal nitride material is disclosed. The method comprises forming a semiconductor device structure comprising an exposed metal material and an exposed metal nitride material. The semiconductor device structure is subjected to a solution comprising water, ozone, and at least one additive to remove the exposed metal nitride material at a substantially greater rate than the exposed metal material. Resulting semiconductor device structures are also disclosed, as are compositions used to form the semiconductor device structures.