Selective Titanium Nitride Film Formation Using SAM Masking
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Solution Overview
Problem
The miniaturization of semiconductor devices has led to insufficient accuracy in position alignment using photolithography technology, necessitating a method for selective film formation on substrates without relying on photolithography, while existing self-assembled monolayer techniques face challenges in maintaining productivity due to the slow adsorption of SAMs and potential decomposition by hydrogen fluoride.
Innovation Solution
A film forming method involving a preparation process, first removal of natural oxide films, formation of a self-assembled monolayer with fluorine and carbon-containing compounds, deposition of titanium nitride films using atomic layer deposition, oxidation, and a second removal process to maintain SAM functionality, thereby enhancing productivity by preventing titanium nitride film formation on insulating films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography technology is used for selective film formation, then position alignment accuracy is sufficient, but miniaturization of semiconductor devices cannot be achieved
Solution Approach 1:
The patent replaces photolithography technology with a self-assembled monolayer (SAM) based method for selective film formation. Instead of using light-based photolithography to define patterns, the invention uses chemical self-assembly of SAMs on specific substrate regions to create masks that prevent titanium nitride film formation in unwanted areas, enabling miniaturization beyond photolithography capabilities
Solution Approach 2:
The patent introduces a self-assembled monolayer (SAM) as an intermediary substance that selectively forms on specific substrate regions. This SAM layer acts as a chemical mediator that prevents titanium nitride deposition in protected areas while allowing deposition in exposed areas, achieving selective film formation without photolithography
2Manufacturing precision
If self-assembled monolayer technique is used for selective film formation, then photolithography is replaced, but productivity decreases due to slow SAM adsorption
Solution Approach 1:
The patent performs preliminary actions by optimizing substrate preparation before SAM adsorption, including controlling substrate cleanliness and surface chemistry. This preliminary preparation ensures that SAM adsorption occurs rapidly and uniformly when the compound is introduced, reducing the overall processing time while maintaining selective film formation accuracy
Solution Approach 2:
The patent changes key parameters of the SAM formation process, including the chemical structure of the SAM compound (using compounds with specific functional groups that enhance adsorption speed), substrate temperature, and compound concentration. These parameter optimizations significantly reduce SAM adsorption time while preserving the selectivity and precision of the method
3Manufacturing precision
If self-assembled monolayer is used to prevent titanium nitride formation, then selective deposition is achieved, but SAM decomposes due to hydrogen fluoride
Solution Approach 1:
The patent employs a disposable SAM layer that is intentionally designed to be temporary and sacrificial. The SAM is formed to provide selective protection during titanium nitride deposition, then deliberately removed in a subsequent step using hydrogen fluoride or other etchants. This approach accepts SAM decomposition as part of the process, using the temporary nature of the SAM to its advantage rather than viewing it as a failure of stability
Solution Approach 2:
The patent converts the potential harm of hydrogen fluoride attacking the SAM into a beneficial removal step. By designing the process to include controlled HF exposure after titanium nitride deposition, the SAM's vulnerability to HF is transformed into a useful mechanism for removing the sacrificial mask layer, cleaning the substrate surface, and preparing for subsequent processing steps
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 method improves semiconductor device productivity by selectively forming titanium nitride films on metal films while preventing unwanted deposition on insulating films, maintaining SAM functionality, and reducing processing time through efficient removal and re-adsorption of SAMs.
Implementation Method 1
a self-assembled monolayer, which suppresses formation of a titanium nitride film, is formed on the insulating film by providing the substrate with a compound for forming the self-assembled monolayer
Implementation Method 2
In the oxidation process, the surface of the substrate is oxidized
Implementation Method 3
a titanium oxide film, which is formed on the metal film and the self-assembled monolayer, is removed by providing the surface of the substrate with the compound for forming the self-assembled monolayer
Data Source
AI summary
A method of selectively forming a film on a substrate includes: a preparation process of preparing a substrate having a surface to which a metal film and an insulating film are exposed; a first removal process of removing a natural oxide film on the metal film; a first film forming process of forming a self-assembled monolayer, which suppresses formation of a titanium nitride film, on the insulating film by providing the substrate with a compound for forming the self-assembled monolayer, the compound having a functional group containing fluorine and carbon; a second film forming process of forming a titanium nitride film on the metal film; an oxidation process of oxidizing the surface of the substrate; and a second removal process of removing a titanium oxide film, which is formed on the metal film and the self-assembled monolayer, by providing the surface of the substrate with the compound.