TiO2薄膜和多层减反膜中厚度，光学常数检测方案(椭偏仪)

Application NofeOptical CoatingsMM-16SE08Spectroscopic Ellipsometry Spectroscopic Ellipsometry Characterisation of TiO2Thin Films and MultilayerAntireflective Coatings by Spectroscopic Ellipsometry Celine Eypert - Application Scientist - Thin Film Division TiO2 is a high bandgap semiconductor that is transparent tovisible light and has excellent optical transmittance.TiO2 hasnigh refractive index and good insulating properties， and asa result it is widely used as protective layer tor very large scaleintegrated (VLSI) circuits and for manufacture of qoptical ele-ments. Additionally TiO2 filmshhave potential uses for anumber of electronic device applications such as dye-sensi-tized photovoltaic cells as well as antireflective (AR)coatings，gas sensors， electrochromic displays，and planarwaveguides. The high dielectric constant of TiO2 allows itsconsideration as an alternative to silicon dioxide for ultrathingate oxide dielectrics used in memory and logic devices. Several methods have been used to prepare titania films， andthese include chemical vapour deposition (CVD)， pulsed la-ser deposition， reactive sputtering and sol-gel deposition.The sol-geltechnique has emerged as one of the most prom-ising techniques as this method produces samples with goodhomogeneity at low cost. To achieve optimum performance it is important to charac-terise the optical constants and thicknesses of thin TiO2 lay-ers accurately. In this note， we show how the Spectroscopic Ellipsometry (SE)，non-destructive optical technique is particularly suitable forthin film characterisation. Characterisation of TiO2 Thin Films For this work TiO2 films were prepared by dip coating on thepre-treated glass substrate. This technique allows to depositthe AR coatings on both sides of the glass substrate. The work was performed using a HORIBA Jobin Yvon MM-16 Spectroscopic Ellipsometer，withan automaticaoniometer. To achieve this characterisation both reflectionand transmission ellipsometry were performed. Ellipsometricmeasurements were collected at an angle of incidence of 70°across the spectral range 430-850 nm， with spectroscopictransmission data acquired at normal incidence. HORIBAJobin Yvon DP2 software allows the measurement and use ofmultiple data types， and the simultaneous analysis of thesetwo models was achieved by the Bound Multimodel function.From the simultaneous analysis of all data， both refractive in-dex and film thicknesses were obtained without ambiguity. The New Amorphous dispersion formula was used to modelthe refractive index for TiO2. Bj(@-Q.)+Cj The New Amorphous dispersion formula is a rewriting oforiginal Forouhi-Bloomer formula (Phys. Rev.B， 34， 7018(1986)). The best model comprises of two layers with the bottom layerbeing less dense than the top layer， and takes into accountthe AR coatings deposited on the both sides of the glass sub-strate. The DP2 Software includes advanced features for the auto-matic correction of backside reflections from transparent sub-strates. Characterisation of TiO， in 8-layer Hi-Lo Index Stack The analysis was performed with the MM-16 SpectroscopicEllipsometer across the range 430-830 nm at an incidentangle of 70°. The best fit model was obtained using a 8-layer model. DP2 software allows characterisation of these structuresusing the special Periodic Structure and Correlated Layerfunctions that allow modelling of repeating pairs of layersused in MQW or Bragg Reflector structures. Conclusion Owing to the sensitivity of the MM-16 Spectroscopic Ellip-someter and the advanced modeling features included in theDP2 software， this note describes the successful characterisa-tion of complicated anti-reflective structures. Accurate and si-multaneous determination of thickness and optical propertieshave been performed in the visible range. Similar analyseshave been applied to other high-k material such as Ta2O5 /glass， Al2O3/ 3*{A2O3/a-Si}/ GaAs， SiO2/ 2*{HfO2 /SiO2)/glass. HORIBAExplore the future Find us at www.jobinyvon.comor telephone：(All HORIBA Jobin Yvon companies were formerly known as Jobin Yvon)HORIBAExplore the future Owing to the sensitivity of the MM-16 Spectroscopic Ellipsometer and the advanced modeling features included in the DP2 software, this note describes the successful characterisation of complicated anti-reflective structures. Accurate and simultaneous determination of thickness and optical properties have been performed in the visible range. Similar analyses have been applied to other high-k material such as Ta2O5 / glass, Al2O3 / 3*{A2O3/a-Si} / GaAs, SiO2 / 2*{HfO2 / SiO2) / glass.