Study On Atomic Layer Deposition Of Alumina Film And Application Of Reflection High Energy Electronic Diffraction In Growth

The level of semiconductor technology is gradually becoming stronger,the size of devices is gradually shrinking,and Al₂O₃films have been extensively studied because of their own high dielectric constant,high band gap,and high light transmittance.As a new high-dielectric gate dielectric material,the dielectric constant k is approximately equal to 9,and the dielectric constant of the currently commonly used material Si O₂is only half of it;as the insulating layer in the field effect transistor,the equivalent oxide thickness becomes larger The tunneling current becomes smaller,and the device performance can be effectively improved.In the preparation method of Al₂O₃thin films,the purity,uniformity,and quality of the thin films grown by atomic layer deposition?ALD?are at a high level,and are not limited by the shape of the substrate.The advantages of ALD technology are increasingly prominent.The ALD technique is a technique in which the precursor pulse enters the deposition chamber in turn,and then a chemical adsorption reaction occurs on the substrate surface to form a thin film.However,ALD technology has not been fully studied how the materials adsorb to the substrate and the reaction kinetics during the deposition process at the beginning of the thin film growth,mainly because there is no matching in-situ monitoring technology.Reflective high-energy electron diffractometer?RHEED?is a material surface analysis method.The biggest advantage is that it is compatible with most thin film deposition systems,monitors the growth of the film in situ,and quickly gives the growth of the film surface in real time;and in the detection It hardly destroys the shape of the sample,and its influence on the sample is negligible.The diffraction fringes and intensity oscillation curves obtained by RHEED can give real-time information such as the quality and rate of the deposited film.In this paper,the influencing factors of Al₂O₃thin film deposited by ALD are studied.The deposited thin film is used as an insulating layer to prepare organic field effect transistors.The integrated system of RHEED and ALD is innovatively proposed to obtain thin film growth data in situ in real time.The following research results have been obtained:First,the Al₂O₃thin film with excellent quality was studied and deposited;the Al₂O₃thin films obtained under different deposition conditions were studied by ellipsometer,atomic force microscope,and X-ray photoelectron spectroscopy,respectively.Among the film growth process parameters,the deposition temperature is a relatively important factor in ALD;the growth temperature directly affects the surface chemisorption in the ALD growth process,which in turn affects the growth rate and surface roughness of the deposited film.Secondly,the pulse time of the precursor is also an important factor.Too much or too little precursor source will affect the deposition rate and uniformity of the film.The best process parameters of Al₂O₃thin film deposited by ALD are given.Then,the organic field effect transistor was prepared by using the Al₂O₃film deposited by ALD as the insulating layer;by analyzing its output characteristic curve and transfer characteristic curve,it was concluded that the Al₂O₃film as the insulating layer can prepare the performance of the current switching ratio I_on/I_off=10⁷Excellent organic field effect transistor device.Finally,the installation realizes the real-time in-situ monitoring function of RHEED during the ALD deposition process;the RHEED is used as an in-situ monitoring instrument in ALD through a two-level differential vacuum system,and the diffraction fringes and intensity oscillation curves of the deposited film are obtained in real time.In addition,the suggestions for improvement of the receiving module of the integrated system and the independent design drawings are given.