Study On The Stress Of SiO₂ Thin Film Grown By APCVD On 200 Mm Heavily Arsenic Doped Silicon Substrate

With the increasing demand for the basic parameters of silicon substrate,more and more attention has been paid to the film stress on the surface.200 mm silicon substrate still accounts for a large proportion in semiconductor device manufacturing,while heavily doped as silicon substrate is widely used in basic device manufacturing.A layer of Si02 film is deposited on the back of heavily-doped substrate to avoid self-doping effect.However,the generation of film stress will change the shape of silicon substrate,which may cause parameter abnormality or etching pattern distortion.The deposition of Si02 thin films can be divided into chemical vapor deposition(CVD)and physical vapor deposition(PVD).The two kinds of CVD is Atmospheric Pressure Chemical Vapor Deposition(APCVD)and Low Pressure Chemical Vapor Deposition(LPCVD).This paper studies the stress produced by Si02 film deposited by APCVD on the surface of silicon substrate.Silicon substrate needs to be sliced,grinded,corroded and cleaned.It includes the influence of process conditions on the stress of Si02 film,the influence of thickness of Si02 film on the stress,and the change of film stress after high temperature heat treatment.Film stress will cause regular BOW of silicon substrate.In this paper,we will calculate the BOW of silicon substrate,and use SEM,TEM and XRD to observe and test the structure and composition of the thin film,so as to complete the research on the stress generation of Si02 thin film deposited by APCVD on 200 mm heavily as doped silicon substrate.The main conclusions are as follows:1.The stress of the Si02 film deposited by APCVD is compressive stress,which decreases with the increase of deposition temperature from 400? to 460?.2.With the increase of the thickness of APCVD film,the stress produced by the film increases.When the film thickness reaches 38000 A,the film stress drops instantaneously due to cracks.3.The stress of Si02 films deposited by APCVD changes after heat treatment at different temperatures.After heat treatment under 500?for 1 hour,the stress change of the film is not obvious.And the film stress changes from compressive stress to tensile stress gradually at 700?.When the temperature is above 1100?,the thermal stress makes the films produce a large tensile stress.4.The structure of the Si02 film deposited by APCVD is very uncompact and complex.The internal structure of the film can be changed by heat treatment.This process causes the change of the stress of the film,and the thickness,hydrophilicity and density of the film will also change accordingly.5.The special structure of the SiO2 films deposited by APCVD causes the stress release during the store time.Under the condition of 23? and 45%humidity at atmospheric pressure,the stress will gradually decrease with the prolongation of placing time,and the stress tends to be stable after 480 hours.Because of the change of structure,the stress release effect of the films after heat treatment changes when they are placed.The stress release of the films after heat treatment above 700? is not obvious.