Etchant Composition for TiN Selectivity Control
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Solution Overview
Problem
The existing etching processes for semiconductor manufacturing struggle to control the selectivity between titanium nitride and tungsten films, particularly in single-type wet etching, where a high etching rate for titanium nitride and adjustable selectivity relative to tungsten are required, and the etching selectivity varies depending on the type of memory device being manufactured.
Innovation Solution
An etchant composition comprising an inorganic acid, an oxidizing agent, and an additive represented by Formula 1, which includes an alkylammonium or alkyl alcohol ammonium salt, is used to achieve a high etching rate for titanium nitride films and adjustable selectivity relative to tungsten films, allowing the etching selectivity to range from 1 to 15, thereby enabling efficient etching in various semiconductor device manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a wet etching process is used to control etching selectivity, then the etching selectivity can be controlled, but the processing time becomes long (several tens of minutes in batch type)
Solution Approach 1:
The patent changes the chemical parameters of the etchant composition by incorporating specific oxidizing agents (hydrogen peroxide, nitric acid, tert-butylhydroperoxide, or 2-butaneperoxide) in controlled amounts (0.1-10% by weight). This chemical parameter modification enables the etchant to selectively etch titanium nitride at high rates while controlling tungsten etching, achieving both high selectivity and rapid processing in single-type wet etching processes.
Solution Approach 2:
The patent creates a composite etchant system by combining inorganic acids (sulfuric acid or phosphoric acid as base) with oxidizing agents and water in specific ratios. This composite composition synergistically enhances the etching capability for titanium nitride while maintaining selectivity control, enabling fast single-type wet etching to replace both batch wet etching and dry etching processes.
2Productivity
If an etchant is designed for high etching rate of titanium nitride, then the productivity increases, but the etching selectivity control becomes difficult
Solution Approach 1:
The patent adjusts the concentration parameters of oxidizing agents (0.1-10% by weight) and inorganic acids (90-99% by weight) to optimize the etching chemistry. This parameter optimization enables the etchant to achieve high titanium nitride etching rates (several nm/min) while maintaining adjustable selectivity (1:1 to 10:1 TiN/W) through controlled chemical reactions.
Solution Approach 2:
The patent applies local quality by making the etchant composition specifically tailored for titanium nitride etching through the addition of oxidizing agents that preferentially react with titanium nitride. This creates a localized chemical environment that enhances etching rate for TiN while controlling the reaction with tungsten, achieving both high productivity and selectivity control.
3Manufacturing precision
If the etching selectivity is increased for DRAM devices, then the etching performance improves, but the etchant composition becomes more complex
Solution Approach 1:
The patent provides a flexible parameter system where the oxidizing agent concentration (0.1-10% by weight) can be adjusted to achieve different selectivity levels. For DRAM applications requiring high selectivity, the oxidizing agent concentration is optimized within this range to enhance TiN etching while suppressing W etching, all within a relatively simple composite etchant system.
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 etchant composition significantly increases the etching rate of titanium nitride films and allows for precise control of etching selectivity, ensuring efficient removal of titanium nitride films relative to tungsten films, reducing particle adhesion and residue generation, and is suitable for both NAND flash and DRAM memory devices.
Implementation Method 1
an oxidizing agent, wherein the etchant composition enables a titanium nitride film to be etched at a significantly high etching rate
Implementation Method 2
including an inorganic acid, an oxidizing agent, an additive represented by Formula 1, and a residual amount of water
Data Source
AI summary
Proposed is an etching composition capable of adjusting an etching selectivity of a tungsten film with respect to a tungsten film. An etching method using the same etching composition is also proposed. The etching composition includes an inorganic acid, an oxidizing agent, an additive represented by Formula 1, and the remaining proportion of water. The etching composition exhibits remarkable effects of providing a high etching rate for a titanium nitride film and of adjusting the etching selectivity of a titanium nitride film with respect to a tungsten film to be in a range of 1 to 15.