Selective Cobalt and Copper Etching via Gas Composition Control
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Solution Overview
Problem
Current methods for metal film etching, such as those using β-diketones, do not provide a means for selectively etching specific metal films like cobalt or copper films on targets with multiple metal films, limiting precise control over etching processes.
Innovation Solution
The method involves controlling the etching rate ratio of cobalt, iron, or manganese films to copper films by adjusting the composition of etching gases, including β-diketones and nitrogen oxides, to selectively etch one film over the other, with specific gas concentrations and temperatures optimizing the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a β-diketone is used to etch metal films, then the metal film can be removed, but selective etching of specific metal films (e.g., cobalt or copper) on targets with multiple metal films cannot be achieved
Solution Approach 1:
The patent applies parameter changes by adjusting the chemical composition of the etching gas mixture. Specifically, it combines a β-diketone-containing gas with a nitrogen oxide-containing gas in controlled proportions. The nitrogen oxide component selectively enhances the etching rate of certain metal films (such as cobalt, iron, or manganese) relative to others (such as copper), thereby achieving selective etching while maintaining efficient metal film removal.
2Ease of manufacture
If wet etching is used to etch metal films, then the etching process is simple, but precise control of etching amount and surface roughness cannot be achieved
Solution Approach 1:
The patent replaces wet etching (liquid-based) with dry etching using a gas-phase chemical process. The etching gas mixture containing β-diketone and nitrogen oxide reacts with the metal film in the vapor phase, enabling precise control over etching depth and surface quality. This substitution of liquid with gas phase chemistry provides better controllability while maintaining process simplicity.
3Productivity
If oxygen is used to etch metal films, then the etching process can proceed, but the temperature range for effective etching is limited
Solution Approach 1:
The patent creates a composite etching atmosphere by combining oxygen (or air) with nitrogen oxide. This composite gas mixture broadens the effective temperature range for metal film etching. The nitrogen oxide component acts as a catalyst or reaction promoter that enables effective etching at lower temperatures while maintaining capability at higher temperatures, thus increasing process adaptability.
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
This approach allows for selective etching of either the cobalt, iron, or manganese film or the copper film, achieving high selectivity and maintaining surface smoothness, thereby improving the precision and efficiency of metal film etching.
Implementation Method 1
a complexing step of complexing the copper oxide to produce a copper complex
Implementation Method 2
reacting a cleaning gas containing a β-diketone and NOx (NO or N2O) with the metal film
Implementation Method 3
an oxidizing step of oxidizing metal copper to produce copper oxide
Implementation Method 4
reacting a cleaning gas containing a β-diketone and NOx (NO or N2O) with the metal film
Implementation Method 5
a subliming step of subliming the copper complex
Data Source
AI summary
The etching method of the present invention includes the step of supplying a first mixed gas containing a β-diketone-containing etching gas and a nitrogen oxide gas to a target having, on a surface, both a first metal film containing cobalt, iron, or manganese and a second metal film containing copper, thereby selectively etching the first metal film over the second metal film, or the step of supplying a second mixed gas containing a β-diketone-containing etching gas and oxygen gas to the target, thereby selectively etching the second metal film over the first metal film.