Selective Titanium Nitride Etching via Chemical Composition
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching titanium nitride and photoresist etch residues without affecting underlying low-k dielectric materials, which is crucial for achieving precise dimensions in microelectronic devices as device sizes decrease.
Innovation Solution
A composition comprising an oxidizing agent, etchant, activator, oxidizing agent stabilizer, passivating agent, and solvent is used to selectively remove titanium nitride and photoresist etch residues, ensuring high selectivity and etch rate relative to low-k dielectric layers, with specific components like hydrogen peroxide and tetramethylammonium hydroxide enhancing the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a wet etching process is used to remove metal hard mask and photoresist etch residues, then the hard mask and residues are effectively removed, but the underlying low-k dielectric material is also affected and removed
Solution Approach 1:
The patent modifies the chemical composition parameters of the wet etching solution by incorporating specific additives including oxidizing agents (such as ammonium persulfate), complexing agents (such as ammonium fluoride), and surfactants (such as hexadecyltrimethylammonium bromide). These parameter changes enable the etching solution to selectively attack titanium nitride and photoresist residues while being inhibited from etching low-k dielectric materials, thereby resolving the selectivity problem.
Solution Approach 2:
The patent introduces intermediary chemical substances that mediate the etching process. The oxidizing agents act as intermediaries to activate the etching reaction on the hard mask surface, while the complexing agents serve as intermediaries to enhance selectivity by forming stable complexes with metal ions from the hard mask. The surfactants act as intermediaries to improve wetting and uniformity of the etching process. These intermediaries enable effective hard mask removal while protecting the low-k dielectric layer.
2Manufacturing precision
If the etch rate is increased to achieve better profile control of vias and trenches, then the critical dimensions can be achieved, but the selectivity between hard mask and low-k dielectric decreases
Solution Approach 1:
The patent achieves both high etch rate and high selectivity by simultaneously optimizing multiple chemical parameters in the etching solution. The concentration ratios of oxidizing agents to complexing agents are carefully controlled, along with pH adjustments and temperature optimization. This multi-parameter optimization enables the etching process to proceed rapidly on titanium nitride while the low-k dielectric remains protected, thus achieving both profile control and minimal damage.
Solution Approach 2:
The etching solution functions as a composite chemical system combining multiple functional components: oxidizing agents for activation, complexing agents for selectivity enhancement, surfactants for uniformity, and buffers for pH control. This composite approach allows the solution to exhibit both high reactivity toward the hard mask (enabling fast etching) and high selectivity (protecting the low-k dielectric), resolving the contradiction between etch rate and selectivity.
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 high etch rate for titanium nitride while minimizing the removal of low-k dielectric materials, ensuring precise etching and maintaining the integrity of microelectronic device structures.
Implementation Method 1
said composition comprising at least one oxidizing agent
Implementation Method 2
said composition comprising at least one etchant
Data Source
AI summary
Compositions useful for the selective removal of titanium nitride and/or photoresist etch residue materials relative to insulating materials from a microelectronic device having same thereon. The removal compositions contain at least one oxidant, one etchant, and one activator to enhance the etch rate of titanium nitride.