Memory Substrate Etching Composition for Tungsten Selectivity
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Solution Overview
Problem
Conventional etching compositions for semiconductor substrates used in memory elements fail to achieve desired performance due to insufficient selectivity between titanium-containing films and metal tungsten, leading to unwanted etching of metal tungsten surfaces during the production of memory elements.
Innovation Solution
An etching composition comprising an oxidizing agent, a fluorine compound, and a metal tungsten corrosion inhibitor, specifically an ammonium salt or heteroaryl salt with a substituted or unsubstituted alkyl group, is used to selectively etch titanium-containing films without etching metal tungsten, thereby preventing corrosion of the metal tungsten surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching composition is used to etch titanium-containing film, then titanium etching is achieved, but metal tungsten surface is also etched (low selectivity)
Solution Approach 1:
A corrosion inhibitor specifically designed for metal tungsten is introduced as an intermediary substance into the etching composition. This inhibitor acts as a mediator that selectively protects the metal tungsten surface from etching by the fluorine compound while allowing the titanium-containing film to be etched. The inhibitor adsorbs onto the tungsten surface, creating a protective layer that prevents harmful interaction between the etchant and the tungsten, thereby achieving high etching selectivity without corroding the metal tungsten.
Solution Approach 2:
The chemical composition parameters of the etching solution are modified by adding specific corrosion inhibitors and adjusting the concentrations of oxidizing agents and fluorine compounds. By changing these chemical parameters, the etching selectivity between titanium-containing film and metal tungsten is optimized. The inhibitor concentration, oxidizing agent strength, and fluorine compound ratio are tuned to achieve conditions where titanium etches rapidly while tungsten remains protected.
2Productivity
If etching composition without corrosion inhibitor is used, then titanium etching rate is high, but metal tungsten corrosion occurs
Solution Approach 1:
The corrosion inhibitor serves as a protective intermediary that allows rapid titanium etching to proceed while simultaneously preventing tungsten corrosion. The inhibitor molecules selectively adsorb onto the tungsten surface, creating a barrier that maintains tungsten integrity even under aggressive etching conditions. This enables high productivity through fast titanium removal while ensuring reliability by preserving the metal tungsten layer without corrosion damage.
3Speed
If strong oxidizing agent and fluorine compound are used for fast etching, then titanium removal speed increases, but metal tungsten corrosion resistance decreases
Solution Approach 1:
The corrosion inhibitor acts as a protective intermediary between the strong oxidizing agent/fluorine compound and the metal tungsten surface. Even when high concentrations of aggressive etchants are used to achieve fast etching speeds, the inhibitor adsorbed on the tungsten surface prevents direct contact and harmful reactions. This allows the system to operate at high etching speeds while maintaining tungsten surface integrity through the mediating protective layer.
Solution Approach 2:
The composition parameters of the etching solution are optimized by adjusting the ratios and concentrations of oxidizing agents, fluorine compounds, and corrosion inhibitors. By carefully balancing these parameters, the system achieves high etching speeds through strong chemical action on titanium while the inhibitor concentration is sufficient to maintain tungsten corrosion resistance even under these aggressive conditions.
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 composition effectively prevents etching of metal tungsten surfaces, ensuring improved performance and selectivity in producing semiconductor substrates for memory elements by effectively inhibiting corrosion from both the surface and side surfaces of the metal tungsten film.
Implementation Method 1
comprising an oxidizing agent (A), a fluorine compound (B), and a metal tungsten corrosion inhibiter (C)
Implementation Method 2
a fluorine compound (B)
Implementation Method 3
a metal tungsten corrosion inhibiter (C) contains at least one selected from the group consisting of an ammonium salt represented by formula (1) and a heteroaryl salt
Data Source
AI summary
Provided is an etching composition for a semiconductor substrate for a memory element capable of providing a semiconductor substrate for a memory element having improved performance. The etching composition for a semiconductor substrate for a memory element comprises: (A) an oxidizing agent; (B) a fluorine compound; and (C) a metal tungsten corrosion inhibitor, wherein (C) the metal tungsten corrosion inhibitor contains at least one selected from the group consisting of an ammonium salt represented by formula (1) and a heteroaryl salt having a C14-C30 alkyl group.