Adsorption and desorption kinetics of airborne ammonia on chromium-coated wafer in cleanroom depending on humidity and NH3 concentration

Ammonia (NH3) is widely used in semiconductor fabrication as an indispensable chemical substance in chemical mechanical planarization (CMP), etching and cleaning processes. The undesired outgassing of residual NH3 gas results in many severe defects on integrated circuits. The front opening unified p...

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Bibliographic Details
Published in:Microelectronic engineering 2020-06, Vol.230, p.111347, Article 111347
Main Authors: Tran, Minh-Phuong, Gonzalez-Aguirre, Paola, Beitia, Carlos, Lundgren, Jorgen, Moon, Sung-In, Fontaine, Hervé
Format: Article
Language:English
Subjects:
Adsorption
Airborne sensing
Ammonia
Ammonia cross-contamination
Chemical-mechanical polishing
Chromium
Chromium-coated wafer
Cleanrooms
Contamination
Desorption
Engineering Sciences
Front opening unified pods (FOUPs)
Humidity
Integrated circuits
Kinetics
Langmuir absorption model
Liquid phases
Mathematical models
Molecules
Outgassing
Relative humidity
Surface chemistry
Wafer/photomask storage
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Summary:Ammonia (NH3) is widely used in semiconductor fabrication as an indispensable chemical substance in chemical mechanical planarization (CMP), etching and cleaning processes. The undesired outgassing of residual NH3 gas results in many severe defects on integrated circuits. The front opening unified pods (FOUPs), which are made of polymers, were introduced as a controlled-microenvironment to protect the processed wafers during transport and storage steps. However, the FOUPs potentially outgas the previous sorbed-NH3 to FOUPs' atmosphere, leading to NH3 cross-contamination. The development of NH3-free liquid phase extraction (LPE) set-up coupled to ionic chromatography (IC) analysis allows sensitive NH3 measurement on wafer surfaces in avoiding the artifacts of airborne NH3 from cleanroom environment. The adsorption and desorption kinetics of NH3 on Cr-coated surface have been determined in cleanroom conditions (21 ± 2°C, 1.0 atm, different NH3 gas concentration (10–35 ppbv) and relative humidity (
ISSN:0167-9317
1873-5568
DOI:10.1016/j.mee.2020.111347