Study On Al₂O₃ Nano-barrier Coating By RF-DBD Atmospheric Pressure Plasma Assisted ALD And Pulse CVD

In the 1970 s,atomic layer deposition?ALD?appeared as a new chemical vapor deposition?CVD?method.This new type of thin film deposition technique has attracted people's attention because of its composition controllability and thickness controllability.However,due to the slow deposition rate,it has not been widely used.From 2000,due to the rapid development in microelectronics industry,the application of ultra-large-scale integrated circuits became more and more important,and ALD technique has been facused again.In this study,the home-made atmospheric pressure radio frequency dielectric barrier discharge?DBD?-assisted atomic layer deposition?PAALD?equipment was used to deposit Al₂O₃ coating,where trimethyl aluminum?TMA?was an aluminum source,and oxygen plasma was an oxidant source.Alumina?Al₂O₃?was grown on a 125 ?m polyethylene terephthalate?PET?substrate to study the impact on the barrier properties of PET.Scanning electron microscope?SEM?,atomic force microscope?AFM?and Fourier transform infrared spectrometer?FTIR?were used to characterize Al₂O₃;the thickness and refractive index of Al₂O₃ nanocoating were measured by ellipsometer;The water vapor transmission rate was measured to characterize the barrier properties of Al₂O₃ coating PET.The main results obtained in this thesis are as follows:?1?The discharge characteristics of low pressure radio frequency dielectric barrier discharge-assisted atomic layer deposition?RF-DBD-PAALD?and atmospheric pressure radio frequency dielectric barrier discharge?RF-DBD?-assisted pulsed chemical vapor deposition?pulse CVD?techniques were studied.The oxygen in plasma was diagnosed by time-resolved optical emission spectroscopy and optical emission spectroscopy,and the discharge parameters were optimized;?2?The process parameters in thermal atomic layer deposition?T-ALD?with ozone as oxidant,or water as oxidant;and low pressure RF-DBD-PAALD with oxygen plasma as oxidant and atmospheric pressure RF-DBD-pulse CVD were TMA / Ar / O₃ /Ar=0.1 / 12 / 0.1 / 14 s,TMA / Ar / H₂O / Ar = 0.07 / 15 / 0.05 / 30 s,TMA / Ar / Ar + O₂ Plasma?200Pa?/ Ar = 0.2 / 15 / 5 / 12 s,TMA / Ar / Ar + O₂ plasma?1atm?/ Ar = 0.5 / 70 / 5 / 50 s,respectively.It was obtained that Al₂O₃ growth rates in T-ALD with ozone as oxidant,water as oxidant,and low pressure RF-DBD-PAALD with oxygen plasma as oxidant and atmospheric pressure RF-DBD-pulse CVD were about 0.155,0.163,0.178 and 0.5 nm / cycle,respectively;?3?When ozone was used as the oxidant in T-ALD and 60 nm Al₂O₃ coated PET surface at 90 ?,WVTR was 0.045 g / m² / day;When water was used as the oxidant in T-ALD,and 65 nm Al₂O₃coated PET surface at 100 ?,WVTR was 0.037 g / m² / day;when oxygen plasma was used as the oxidant at low pressure RF-DBD-PAALD and 54 nm Al₂O₃ coated PET surface at 80?,WVTR was 0.031 g / m² / day;In atmospheric pressure RF-DBD-pulse CVD,65 nm Al₂O₃ coated PET surface at 85?,WVTR was 0.089 g / m² / day.According to the temperature conditions that achieve the same barrier requirements,it is concluded that the ozone oxidation capacity is higher than that of water,and the atomic oxygen oxidation capacity generated by plasma is higher than that of ozone.RF-DBD-PAALD can effectively decrease the deposition period,reduce the deposition temperature and improve the deposition efficiency.If the coating was deposited in the low pressure RF-DBD-PAALD the moisture permeability was 181 times smaller than that in the original film?5.6g / m².day?;whereas if the coating was deposited in the atmospheric pressure RF-DBD-pulse CVD WVTR was decreased by 63 times.