IEC TR 63258 pdf free download

IEC TR 63258 pdf free download.Nanotechnologies – A guideline for ellipsometry application to evaluate the thickness of nanoscale films.
4.2 Measurement procedure
4.2.1 Sample preparation for system check
Before the actual sample measurement is performed, it is necessary to check the system’s accuracy. To make it possible, a reference sample with known thickness and/or refractive index should be used. The reference samples such as thermally oxidized SiC2 on Si are available.
Ellipsometry is very sensitive to physical and chemical properties of the thin film material, its surface and the properties at the film—substrate interface.
4.2.2 Experimental procedure for system check
The general protocol of ellipsometry measurement is standardized to evaluate thin films.
— Step 1: Positioning of the reference sample on the stage.
— Step 2: Adjustment of the height and tilt.
— Step 3: Measurement of the reference sample.
— Step 4: Data analysis.
— Step 5: Result of thickness or refractive index should be within I % of the guaranteed values.
— Step 6: If the obtained result fulfils the condition of step 5, start to measure the test sample. If not, the system needs additional check.
It is advisable to check the system at the required angle of incidence.
4.2.3 Sample handling
Ellipsometry is very sensitive to physical and chemical properties of the sample’s surface, so it is advisable to keep the sample in a clean and dry place after the preparation. Touching and scratching the surface should be avoided, because non-professional cleaning might affect the surface state and therefore change the result.
4.2.4 Experimental procedures
The general protocol of ellipsometry measurement is as follows.
— Step I: Positioning of the sample on the stage.
— Step 2: Adjustment of the angle of incidence, height and tilt.
— Step 3: Measurement of the sample.
— Step 4: Data analysis.
— Step 5: Validation of analysis result.
NOTE This protocol is valid for non scattering and isotropic sample planes.
In order to minimize the data variation, the following practical recommendations apply.
I) The ellipsometry measurement should be done at an angle of incidence close to the Brewster’s angle of the substrate.
2) The ellipsometry measurement should be done over a measurement wavelength range as wide as possible. For example, if there is absorption in the visible range, it needs to be measured including the near-infrared range.
3) The fitting analysis should be performed by changing the initial value of the film thickness and the type of dispersion formula at the time of analysis. The comparison should be done to confirm that equivalent results can be obtained. See Annex A.
5 Reporting data
— Documentation of the environment (temperature, humidity, cleanroom or normal ambient).
— Instrument used, including specification of the measurement programs and settings.
— Visual appearance of samples (to document any dust, cracks, moisture or other noticeable visual items).
— Individual measurement values.
— Calculated averages if applicable.
6 Data analysis I interpretation of results
6.1 General
Ellipsometry measures changes in light polarization to evaluate the material properties, such as film thickness and dielectric constants. In spectroscopic ellipsometry, the measured spectra are analysed by using the model fitting. Generally, in the case of nanomaterials, there is typically a surface oxide, roughness, and intermixing at the heterointerface of the sample. The common procedure to deduce material properties from ellipsometry measurements is shown in Figure 2. Evaluations of nanomaterial characteristics by using the ellipsometry measurements are shown in Annex B.
In the case of ellipsometry measurements, the intensities or polarization state ratios (complex relative amplitude attenuation) are measured and the ellipsometric angles, that is ellipsometric transfer quantities f’ and A, are calculated. No direct access exists to the parameters in which we are usually interested, such as the dielectric functions (,), refractive indices (N), compositions and film thicknesses (d).
In general, for any planar structure on the substrate, Y and A could be calculated if thicknesses and refractive indices are known. On the other hand, for the inverse case, even if q’ and 4 are known, d and N could not be directly calculated. In order to obtain d and N for each layer, modelling is required. The modelling approach is based on the assumption that the measured Y(A) and 4(A) change at each wavelength according to dispersion law.
Determination of material properties could be done by describing the fundamental response of a material to an applied electromagnetic field. Each material has unique energy dependence of dielectric function c. In the visible-near UV range, dielectric response is determined almost entirely by the electronic properties of a material.IEC TR 63258 pdf download.