Papers by Keyword: SiO₂ Film

Abstract: Film bulk acoustic wave resonators (FBARs) with relatively high Q-factor are considered good candidates to be used in the RF module of chip-scale atomic clocks (CSACs). In order to simulate and analyze the resonant properties, the Mason equivalent circuit of the FBAR device is introduced, which consists of five parts including top electrode layer, low temperature silicon oxide layer, piezoelectric layer, bottom electrode layer and a composite support structure layer. With the practical processing conditions considered, the piezoelectric layer with a reasonable thickness of 1.30um is selected to achieve a FBAR device with resonant frequency 4.60GHz and Q-factor 278 by the simulation and analysis. In order to further improve the Q-factor, SiO₂ thin films with thicknesses from 0.10um to 0.50um placed between the top electrode and piezoelectric layer are introduced. However, as the SiO₂ thin film is introduced, the resonant frequency of the FBAR device will drop. In order to keep the resonant frequency fixed to 4.60GHz, the thickness of the piezoelectric layer is adjusted. Finally, the FBAR device resonating at 4.60GHz with Q-factor 627 is achieved, the thicknesses of the SiO₂ film and piezoelectric layer of which are 0.20um and 0.69um respectively. The Q-factor of the FBAR device improves about 350, and the FBAR device is expected to be used in CSACs.

Abstract: In this paper, the glass was coated by silica film using sol-gel method. The influence of preparation conditions (such as the ratio of water to silica, aging time of the sol and the drying time of the film) on the film cracking was studied. Results show that when the ratio of water to silica is 1, aging time 72 h and drying time 6 h, the obtained film is crack-free. The film consists of nanoparticles distributed in silica gel. The thickness is about 45~60 nm. The visible light spectra measurements indicate that the coated film increase the transparency of the glass substrate. After the acid treatment and a scratching of 50 times, the spectra remain unchanged, suggesting a good acid and abrasion resistance of the prepared film.

Abstract: SiO₂/PET composite packaging film was prepared by depositing SiO₂ on PET film substrates through magnetron sputtering technology. The state of SiO₂ particles and its dispersion properties in PET substrates were characterized by scanning electron microscope (SEM) and bonding strength tester. The effects of the sputtering process parameters and intermediate layer on the bonding strength of the coating-substrate system were investigated. Results show that the bonding strength of coating-substrate system firstly increases and then decreases with the increase of sputtering process parameters. It is up to a maximum at the argon flow of 10 mL/min, radio-frequency power of 250 W and sputtering time of 70 min; and it is 0.14 MPa, 0.22 MPa and 0.19 MPa, respectively. The bonding strength of coating-substrate system increases with the increasing background pressure. Meanwhile, we find that the bonding strength of coating-substrate system is improved by depositing A1₂O₃ intermediate layer between SiO₂ film and PET substrates.

Abstract: The anti-reflective SiO₂ film on glass was prepared by sol-gel process and dip-coating method.The effect of drawing speed on properties of the SiO₂ film was studied. The transmittance was tested by light spectrum transmittance testing system,the thickness and refractive index of SiO₂ film was tested by spectroscopic ellipsometer. With increasing of the drawing speed from 100mm/min to 300 mm/min, the average of transmittance increment at first increased and then decreased, which reached the maximum 4.24% at the speed 150mm/min. The relations among transmittance, thickness (d) and refractive index (n) of the SiO₂ film was dicussed.

Abstract: In the paper, ion-assisted e-beam evaporation (IAEE) method was used to deposit SiO2 film on CBA(CaO-Al2O3-BaO) glass substrate, and the influence of processing parameters on the performance of the thin films was studied. The result shows that the ion energy, substrate temperature and evaporating rate are key factors that affect the abrasion resistance and transmission of the SiO2 film. Heat treatment was used to eliminate the absorption of H2O in spectrum range of 2.7~3.5μm. SiO2 film with good abrasion resistance and high transmission in spectrum range 3.0~5.0μm was deposited successfully on the special glass substrate.

Abstract: The convex surface of the infrared dome is exposed to the harsh environment of the outside world, and therefore requires a coating which not only increases transmission but is able to withstand rain erosion so as to enhance system performance. This paper deals with the techniques that were developed to deposit a uniform thick SiO2 coating for sapphire dome by radio frequency magnetron sputtering. Results show that average transmission increment in wavelength range from 3 to 5um for the sapphire dome coated on convex surface was more than 4.0%. The transmission non-uniformity over the convex surface of the coated sapphire dome was less than 1.7%.