Semiconductor Preclean Using In Situ HF for Native Oxide Removal
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Solution Overview
Problem
The fabrication of semiconductor devices faces challenges in removing native oxides from substrates, which can interfere with etching and material layer formation, leading to increased defects and impact electrical performance.
Innovation Solution
A semiconductor processing system utilizing an anhydrous hydrogen fluoride delivery system and a water vapor delivery system, where anhydrous hydrogen fluoride and water vapor are controlled to generate hydrofluoric acid in situ on the substrate surface, effectively removing native oxides without using radical species, while minimizing corrosion and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning methods are used to remove native oxides from substrates, then cleaning effectiveness is improved, but substrate damage and defect increase occur
Solution Approach 1:
The invention changes the chemical parameters of the cleaning process by using anhydrous hydrogen fluoride with controlled water content (1-100 ppm) instead of conventional wet chemicals. This parameter change enables effective oxide removal while minimizing substrate damage, as the controlled anhydrous environment provides selective etching of oxides without the harmful effects of conventional wet cleaning methods
Solution Approach 2:
The invention employs an inert atmosphere by using anhydrous hydrogen fluoride as the cleaning medium. The anhydrous nature creates a controlled inert environment that prevents unwanted chemical reactions and substrate damage while maintaining cleaning effectiveness. The system maintains this inert environment through specialized delivery mechanisms that prevent moisture contamination
2Productivity
If radical species are used for oxide removal, then cleaning speed is improved, but substrate etching and contamination increase
Solution Approach 1:
The invention substitutes the mechanical/chemical action of radical species with a controlled chemical vapor deposition approach using anhydrous hydrogen fluoride. Instead of using aggressive radical chemistry that causes substrate etching, the system uses controlled molecular HF that selectively reacts with native oxides at lower rates, maintaining cleaning effectiveness while eliminating substrate damage and contamination
Solution Approach 2:
The invention changes the chemical state and reactivity parameters by using molecular anhydrous HF instead of radical species. This parameter change reduces the aggressive etching action while maintaining oxide removal capability, thereby eliminating substrate contamination and damage while preserving cleaning speed
3Device complexity
If moisture is present in hydrogen fluoride delivery system, then system simplicity is improved, but corrosion and component degradation increase
Solution Approach 1:
The invention maintains an inert anhydrous atmosphere throughout the delivery system to prevent corrosion. By keeping water content below 100 ppm through specialized delivery mechanisms and moisture traps, the system protects metal components from hydrofluoric acid corrosion while maintaining operational simplicity. The inert environment prevents the formation of corrosive HF acid on component surfaces
Solution Approach 2:
The invention introduces intermediary components such as moisture traps and controlled delivery mechanisms that mediate between the hydrogen fluoride source and the reaction chamber. These intermediaries remove trace moisture without adding significant complexity, thereby protecting downstream components from corrosion while maintaining system simplicity and reliability
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 efficient removal of native oxides without etching the substrate and reduces corrosion in the processing system, maintaining the integrity of the substrate and extending the life of processing system components.
Implementation Method 1
anhydrous hydrogen fluoride and water vapor are controlled to generate hydrofluoric acid in situ on the substrate surface, effectively removing native oxides
Implementation Method 2
one or more upstream heater jackets thermally coupled to the pressure gauge, the purifier, and the first anhydrous hydrogen fluoride conduit
Data Source
AI summary
In some embodiments, a method for semiconductor processing preclean includes removing an oxide layer from a substrate using anhydrous hydrogen fluoride in combination with water vapor. A system for the preclean may be configured to separate the anhydrous hydrogen fluoride and the water vapor until they are delivered to a common volume near the substrate. Corrosion within components of the system may be limited by purification of anhydrous hydrogen fluoride, passivation of components, changing component materials, and heating components. Passivation may be achieved by filling a gas delivery component with anhydrous hydrogen fluoride and allowing the anhydrous hydrogen fluoride to remain in the gas delivery component to form a passivation layer. Consistent water vapor delivery may be achieved in part by heating components using heaters.