Properties Study Of Alumina Nanofilm Prepared By Low Temperature Atomic Layer Deposition

In recent years,flexible electronic devices with extended and bending properties have attracted much more attentions in the fields of medical treatment,display,information technology,etc.However,flexible devices are vulnerable to external material,restricting its development.Therefore,the use of dense high barrier film on the device package can effectively improve its stability for this problem.Atomic layer deposition（ALD）is a unique chemical vapor deposition technology with the self-limiting characteristic.It has the advantages in preparing dense and uniform thin films,imparting it great application potentials in the field of flexible packaging.In this paper,the flexible materials are encapsulated by films deposited via atomic layer deposition,and alumina films with high barrier properties are fabricated at low temperature.In this paper,it is proposed to encapsulate the flexible materials using ALD at low temperature,and to study the encapsulation properties of the flexible materials,showing good characteristics.The main contents of this paper include:（1）Based on the classical atomic layer deposition theory,the influences of the aspect ratio of the cavity on the deposition process are analyzed by the deposition experiment and the fluid dynamic simulation.The cavity structure is optimized and the aspect ratio was selected at 1:5 which makes it more suitable for low temperature deposition.（2）The deposition of low temperature alumina thin films was realized by using the tube-flow atomic layer deposition equipment and optimizing the process.The results of the electrical performance test showed that the deposited alumina film has high insulation and low surface defects.The results of X-ray photoelectron spectroscopy showed that the growth of flexible substrate was similar to that of silicon wafer.The use of nanoindentation to estimate the film stress provides a way to calculate the mechanical properties.（3）A gas permeability measurement system based on mass spectrometry is self-built with limited gas permeability measurement accuracy as low as 3.2×10^-7g/m²·day.This system has the precision superiority compared with the commercial equipment,and also has the advantages such as simple handling,safe operation,high efficiency,etc.The single layer alumina film shows good permeability barrier properties according to the water vapor permeability tests.