Specific Process Knowledge/Thin film deposition/Deposition of MgO: Difference between revisions
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=MgO Sputtering= | =MgO Sputtering= | ||
This page presents the results of MgO deposition using <b>RF sputtering</b> in Sputter-System Lesker, now commonly known as "Old Lesker". The deposition target is <b>MgO</b>, and a small fraction of O<sub>2</sub> as reactive gas | This page presents the results of MgO deposition using <b>RF sputtering</b> in Sputter-System Lesker, now commonly known as "Old Lesker". The deposition target is <b>MgO</b>, and a small fraction of O<sub>2</sub> has been added as a reactive gas to improve the stoichiometry. Source #5 (RF) was used. | ||
The prepared samples were investigated | The prepared samples were investigated using Spectroscopic Ellipsometry, X-ray Photoelectron Spectroscopy, and, most importantly, the X-ray Reflectivity method. The focus of the study was the deposition conditions and the analysis of the refractive index. | ||
The process recipe in a Sputter-System (Lesker) is | The process recipe in a Sputter-System (Lesker) is as follows: | ||
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X-ray reflectivity (XRR) profiles for MgO films at four different deposition times (4h, 8h, 12h, 16h) has been obtained using Rigaku XRD SmartLab equipment with standard 2<math>\theta</math> / <math>\omega</math> scans. The voltage and current settings for the Cu X-ray tube were standard | X-ray reflectivity (XRR) profiles for MgO films at four different deposition times (4h, 8h, 12h, 16h) has been obtained using Rigaku XRD SmartLab equipment with standard 2<math>\theta</math> / <math>\omega</math> scans. The voltage and current settings for the Cu X-ray tube were standard: 40 kV and 30 mA. The incident optics contained an IPS (incident parallel slit) adapter with a 5 ° Soller slit. Other slits: IS=0.03mm, RS1=0.03mm, and RS2=0.075mm. Step size: 0.01 and measurement time - 5s for each point. The fitting procedure was performed using commercial GlobalFit software, assuming a model based on a Si substrate with a native oxide, followed by the deposited complex MgO film, as illustrated in the model figure. The results are summarized in a table below. | ||
<gallery caption="Figure 2. XRR measurements and modelling." widths=" | <gallery caption="Figure 2. XRR measurements and modelling." widths="400px" heights="350px" perrow="2"> | ||
image:eves_MgO_XRR_4h_20220105.png|<b>4 hours</b>. | image:eves_MgO_XRR_4h_20220105.png|<b>4 hours</b>. | ||
image:eves_MgO_XRR_8h_20220105.png|<b>8 hours</b>. | image:eves_MgO_XRR_8h_20220105.png|<b>8 hours</b>. | ||
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==X-ray Photoelectron Spectroscopy== | ==X-ray Photoelectron Spectroscopy== | ||
XPS profiles for MgO films has been obtained using XPS K-Alpha equipment. Here only 12h deposition sample is shown, but all samples look similar. Depth profiles have been acquired using monoatomic Ar+ bombardment. The etching time is 10s. 3000 eV energy | XPS profiles for MgO films has been obtained using XPS K-Alpha equipment. Here, only a 12h deposition sample is shown, but all samples look similar. Depth profiles have been acquired using monoatomic Ar+ bombardment. The etching time is 10s. A 3000 eV energy and high current setting is used. | ||
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The spectroscopic ellipsometry measurements were conducted | The spectroscopic ellipsometry measurements were conducted using a VASE Ellipsometer. The purpose of the investigation is to see how the change in thickness affects the shape of the refractive index. Other parameters, such as layer thickness, were also extracted. | ||
The Cauchy layer is a commonly used layer for | The Cauchy layer is a commonly used layer for determining the optical constants of transparent or semitransparent films (Dielectric or Semiconductors below the fundamental bandgap). Over part of the spectral range, the optical constants of these materials can be represented by an index that varies slowly as a function of the wavelength and the exponential absorption tail. The index of refraction of the Cauchy layer is represented by an inverse power series containing only even terms, and a simple exponential tail represents the extinction coefficient. | ||
<math> n (\lambda) = A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}} </math> <br> | <math> n (\lambda) = A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}} </math> <br> | ||
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<math> k (E) = k\cdot e^{exp(E-BandEdge)} </math> <br> | <math> k (E) = k\cdot e^{exp(E-BandEdge)} </math> <br> | ||
There are three terms (A, B, and C) for the index of refraction (n), and there are three additional terms to describe an Urbach absorption tail. The <i>k</i> Amplitude and <i>exp</i> (Exponent coefficient) are fit parameters for determining the shape of the extinction coefficient dispersion. The <i>BandEdge</i> parameter can be set manually but is not a | There are three terms (A, B, and C) for the index of refraction (n), and there are three additional terms to describe an Urbach absorption tail. The <i>k</i> Amplitude and <i>exp</i> (Exponent coefficient) are fit parameters for determining the shape of the extinction coefficient dispersion. The <i>BandEdge</i> parameter can be set manually, but it is not a fitting parameter since it is directly correlated with the k Amplitude parameter (the extinction coefficient equals k Amplitude at the band edge). Here, the <i>BandEdge</i>=400nm | ||