Thickness measurement of nm HfO₂ films

Abstract

Main text A pilot study for the thickness measurement of HfO2 films was performed by the Surface Analysis Working Group (SAWG) of the Consultative Committee for Amount of Substance (CCQM). The aim of this pilot study was to ensure the equivalency in the measurement capability of national metrology institutes for the thickness measurement of HfO2 films. In this pilot study, the thicknesses of six HfO2 films with nominal thickness from 1 nm to 4 nm were measured by X-ray Photoelectron Spectroscopy (XPS), X-ray Reflectometry(XRR), X-ray Fluorescence Analysis (XRF), Transmission Electron Spectroscopy (TEM), Spectroscopic Ellipsometry (SE) and Rutherford Backscattering Spectrometry (RBS). The reference thicknesses were determined by mutual calibration of a zero-offset method (Medium Energy Ion Scattering Spectroscopy (MEIS) of KRISS) and a method traceable to the length unit (the average thicknesses of three XRR data except the thinnest film). These reference thicknesses are traceable to the length unit because they are based on the traceability of XRR. For the thickness measurement by XPS, the effective attenuation length of Hf 4f electrons was determined. In the cases of XRR and TEM, the offset values were determined from a linear fitting between the reference thicknesses and the individual data by XRR and TEM. The amount of substance of HfO2, expressed as thickness of HfO2 films (in both linear and areal density units), was found to be a good subject for a CCQM key comparison. To reach the main text of this paper, click on Final Report. The final report has been peer-reviewed and approved for publication by the CCQM.

Experimental determination of reference intensity ratio essential for accurate thickness measurement of HfO2 ultrathin films by XPS

“…11 In addition to the errors of $10% in L C and $20% in d C , 18,19 the standard uncertainties of d SiO2 , L SiO2 , and θ were 0.05 nm, 0.019 nm, and 2 , respectively. 7,8,11,20 Therefore, R 0Àbulk = 4.65, and a standard uncertainty of 0.05 was obtained.…”

“…Before the growth of the HfO 2 film, a 2 nm SiO 2 layer was grown on the Si (100) substrate by thermal oxidation to prevent the diffusion of O atoms from the HfO 2 film to the Si (100) substrate. [7][8][9] Figure 1 presents the sample structures: (A) the ultrathin HfO 2 films, (B) the bulk material of 20 nm HfO 2 film, thicker than a few attenuation lengths of the photoelectrons and is effectively a bulk sample for XPS, and (C) the Si substrate with a 2 nm SiO 2 layer. Before the XPS analysis, all the samples were cleaned with high purity (99.9%) IPA and then ultrasonically agitated 10 based on the procedure used in a key comparison of CCQM-K32.…”

“…This is the same as the international comparisons CCQM-P190, "Thickness measurement of nm HfO 2 films," and CCQM-K157, "Measurement of the amount of substance of HfO 2 expressed as the thickness of nm films." 7,8 Although the difference in the two EALs is about 5%, 17 we attempted to evaluate the uncertainty due to the assumption by numerically calculating the d HfO2 using the values of L HfO2 Si2p = 2.02 nm (as shown in Section 3.5) and L HfO2…”

TiN hard coating as a candidate reference material for surface metrology in chemistry: characterization and quantification by bulk and surface analyses techniques

“…In a Latin-American context, the CENAM has participated in the "Mexican Society of Materials", where several research institutes as well as private and government companies are included. A substantial growth in the industrialization of technology has allowed an increasing need for researching and developing reference materials (RMs) since the existing market for these materials is still very low (Mathia et al, 2011;Kim et al, 2021;Wolfgang et al, 2022;Ferrarini et al, 2022).…”

The Surface Analysis Working Group at the Consultative Committee for Amount of Substance, Metrology in Chemistry and Biology: A successful initiative by Martin Seah

“…Measurement of the amount of substance of HfO 2 expressed as the thickness of nm films lead by KRISS (for the related pilot study, see Kim et al 15 ). This project addresses recent needs for traceable measurements in the semiconductor industry.…”