Selective NiPt Etching via Chloride-Enhanced Oxidation
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Solution Overview
Problem
Current wet etching processes struggle to selectively remove Nickel Platinum (NiPt) material from microelectronic substrates without affecting underlying layers like NiPt silicide and titanium nitride, requiring a chemistry that achieves high etch rates for NiPt while minimizing etching of these other materials.
Innovation Solution
An aqueous etching composition comprising an oxidizing agent, a strong acid, and a source of chloride is used to selectively remove NiPt material, achieving high etch rates for NiPt while maintaining low etch rates for NiPt silicide and titanium nitride, thereby preserving these underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional wet etching processes are used to remove NiPt material, then NiPt can be removed from the substrate, but the underlying layers such as NiPt silicide and titanium nitride are also etched adversely
Solution Approach 1:
The patent changes the chemical parameters of the etching solution by combining specific oxidizing agents (potassium permanganate, sodium persulfate, hydrogen peroxide), strong acids (sulfuric acid, methanesulfonic acid, nitric acid), and chloride sources (ammonium chloride, hydrochloric acid) in controlled concentrations to achieve differential etching rates. This parameter optimization enables high selectivity where NiPt etches rapidly while NiPt silicide and titanium nitride remain substantially unchanged.
Solution Approach 2:
The etching solution functions as a composite chemical system integrating multiple active components: oxidizing agents that activate the etching process, strong acids that provide the etching medium, and chloride sources that enhance selectivity. This composite chemistry creates a synergistic effect that achieves both high productivity in NiPt removal and high manufacturing precision through selective action.
2Productivity
If high etch rates are achieved for NiPt removal, then productivity is improved, but selectivity against other materials deteriorates
Solution Approach 1:
The chloride ions act as intermediaries that mediate between the oxidizing agents and the NiPt material, facilitating rapid etching of NiPt while being less effective against NiPt silicide and titanium nitride. The chloride source (ammonium chloride or hydrochloric acid) provides this selective mediation, enabling high productivity without the harmful side effect of etching underlying layers.
Solution Approach 2:
The use of strong oxidizing agents (potassium permanganate, sodium persulfate, hydrogen peroxide) accelerates the oxidation of NiPt to enable high etch rates. These strong oxidants work in conjunction with the acidic medium and chloride ions to achieve rapid NiPt removal while the oxidization resistance of NiPt silicide and titanium nitride protects them from etching.
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 achieves high etch rates for NiPt material while minimizing etching of NiPt silicide and titanium nitride, ensuring the desired materials are retained on the microelectronic substrate, thus enhancing the precision and effectiveness of the etching process.
Implementation Method 1
an aqueous etching composition comprising: an oxidising agent; a strong acid; and a source of chloride
Implementation Method 2
a strong acid
Implementation Method 3
a source of chloride
Data Source
AI summary
A method of selectively removing NiPt material from a microelectronic substrate, the method comprising contacting the NiPt material with an aqueous etching composition comprising:an oxidising agent;a strong acid; anda source of chloride.