一般財団法人材料科学技術振興財団　MST List of Products and Services

In oxide ReRAM, it was suggested that oxygen diffusion associated with the application of an electric field is related to memory operation (resistance change). Since SIMS analysis allows for the measurement of isotopes, utilizing the isotope 18O ion implantation technique enables the tracking of oxygen diffusion. For devices where 18O was locally implanted, a bridge structure that serves as the operating region was formed by applying an electric field, and elemental mapping revealed that the intensity of 18O in the bridge area was weak, indicating localized reduction.

When measurements are conducted using a two-dimensional detector, information about the diffraction angle (2θ) as well as the tilt direction (χ) can be obtained simultaneously. The observed two-dimensional diffraction pattern can visualize characteristics such as the crystallinity and orientation of the material, making it effective for evaluating materials where orientation affects their properties.

The miniaturization of devices has increased the need for evaluating the depth distribution of impurities in extremely shallow regions. To conduct an accurate assessment, SIMS analysis using a primary ion beam with lower energy (below 1 keV) is required. Figure 1 shows examples of measurements of Si wafers implanted with BF2+ 1 keV, P+ 1 keV, and As+ 1 keV, using a primary ion beam energy of 250 eV to 300 eV.

For extremely thin films with a thickness of a few nanometers or less, such as natural oxide films on silicon wafers and silicon nitride thin films, we will measure the Si2p spectrum of the sample's surface. By performing waveform analysis on the obtained spectrum, we will determine the proportion of each bonding state and estimate the film thickness from this result and the average free path of photoelectrons (Equation 1).

The transparent oxide semiconductor IGZO thin film is being researched and developed as a TFT material for displays. IGZO is a material whose properties change significantly based on the composition of the film, the presence of oxygen vacancies, and crystallinity, making it important to consider the correlation with film quality. We will introduce a case where the crystallinity, film thickness, and film density of three types of IGZO thin films with different heating temperatures were measured and compared using XRD and XRR. It was confirmed non-destructively that crystallization progresses at high temperatures, resulting in higher film density.

We will introduce a case where the thickness of extremely thin films, such as natural oxide films on silicon wafers and silicon nitride thin films, which are less than a few nanometers thick, was calculated using XPS analysis. By measuring the Si2p spectrum of the surface of the Si wafer and performing waveform analysis on the obtained spectrum, we can determine the ratio of the presence of each bonding state, and from this result, it is possible to estimate the film thickness based on the average free path of photoelectrons (Equation 1). XPS allows for non-destructive and simple calculation of thin film thickness on substrates as broad average information.

In the pursuit of improving the efficiency of CIGS thin-film solar cells, various buffer layer materials have been investigated for controlling the band structure and crystallinity from the light absorption layer to the transparent electrode. This presents a case study of various evaluations conducted using X-rays on Zn-based buffer layers deposited on a flattened substrate. Comparisons can be made between different levels based on deposition conditions and various processes after deposition.

The IGZO thin film, a transparent oxide semiconductor, is being researched and developed as a TFT material for displays; however, there are still challenges regarding the stability of TFT characteristics for practical use. To address this issue, it is important to elucidate the IGZO film formation mechanism. By clarifying the electronic states of metal elements and their local structures in IGZO thin films through XAFS analysis using synchrotron radiation, it is possible to gain insights into the IGZO film formation mechanism. This paper presents a case study of local structure analysis of IGZO thin films using Zn-K edge XAFS spectra.

IGZO films are materials that are being researched and developed as TFT materials for displays. The carrier concentration changes according to the hydrogen concentration in the IGZO film, leading to variations in electrical characteristics. Therefore, it is necessary to accurately measure the hydrogen concentration in the film for evaluating the device characteristics and reliability of devices using IGZO films. We will introduce a case study that evaluated the hydrogen concentration in IGZO films under different heating conditions using SIMS.

IGZO films are materials that are being researched and developed as TFT materials for displays. There are concerns that the diffusion of metal elements into the IGZO film may degrade the TFT characteristics, so it is necessary to accurately measure the metal concentration within the film for evaluating the device characteristics and reliability using IGZO films. We will introduce a case where the Ti concentration in the IGZO film was evaluated from the opposite side of the metal electrode using SSDP-SIMS.

IGZO films are materials that are being researched and developed as TFT materials for displays. The presence or absence of crystalline structure in the thin film may affect the TFT characteristics and reliability, necessitating local crystalline evaluation within the device. We will introduce a case where the crystalline structure in IGZO films was continuously evaluated using electron diffraction measurements from TEM.

IGZO films are materials that are being researched and developed as TFT materials for displays. Since they are composed of multiple metal elements, it is important to understand how the composition, bonding state, and electronic state change depending on the process. We will introduce examples of evaluating the composition, bonding state, and electronic state of IGZO film surfaces using XPS and UPS.

This text introduces an example of evaluating the composition and bonding states of GaN films used in LEDs and power devices using XPS. Understanding how the composition and bonding states change due to film formation conditions and surface treatments is effective for process management. It is important to appropriately select the X-rays used during the evaluation according to the purpose. Measurement conditions for each focus will also be presented.

XPS is a surface-sensitive technique, so carbon derived from organic contaminants due to the atmosphere is detected at a significant level. Reducing the influence of this carbon from organic contaminants is important for evaluating the original composition of the film. Typically, Ar ion sputtering is used to remove organic contaminants, but damage caused by sputtering may prevent the evaluation of the film's original composition and bonding states. We present an example where the influence of carbon from organic contaminants was reduced by removing the surface oxide layer using wet etching instead of Ar ion sputtering.

In XPS analysis, the binding state evaluation of the material surface is conducted by observing the energy of photoelectrons obtained through X-ray irradiation. It allows for the assessment of whether metal elements are in an oxidized state, and for elements with significant energy shifts (chemical shifts) due to oxidation, it also enables the evaluation of the presence and proportion of multiple valences. Below are the main metal elements and oxides for which multiple valence evaluations are possible.

The electron diffraction method using an electron microscope is classified into three types based on the way the electron beam is incident on the sample. The characteristics of each type and examples of data are presented. It is necessary to choose the appropriate method according to the size of the evaluation object and the analysis purpose.

Gallium oxide (Ga2O3) has a wider bandgap than SiC and GaN, and possesses excellent physical properties, making it a material of interest for high-efficiency, low-cost power devices. Controlling the impurity concentration, which affects the characteristics, is crucial in wafer development. This document presents a case study of quantitative analysis of metal elements in the vicinity of Ga2O3 films. TOF-SIMS allows for highly sensitive evaluation even in very shallow regions.

Silicon oxide films are widely used as gate dielectrics in MOS devices and as anode materials in lithium-ion secondary batteries, but it is known that the presence of intermediate oxides and the bonding states at the interface have a significant impact on device characteristics. XAFS measurements using synchrotron radiation can detect information from a depth of several tens of nanometers from the sample surface, allowing for non-destructive analysis of the structure and bonding states in both bulk and at the interface. This document presents a case study investigating the presence of intermediate oxides in silicon oxide films using XAFS.

The band gap of thin film samples has been measured using analytical methods such as UV-Vis, PL, and XPS, but the cases that could be evaluated were limited due to constraints related to the sample structure, such as materials, film thickness, and substrates. This time, through the combined analysis of XAFS and XPS, it has become possible to reduce the constraints of the sample structure and achieve a higher precision band gap evaluation than before. This method is particularly effective for the evaluation of various oxide and nitride films. This document presents a case study on the band gap evaluation of silicon nitride (SiN) films. Measurement methods: XAFS, XPS. Product fields: solar cells, lighting, oxide semiconductors, power devices. Analysis purpose: evaluation of electronic states. For more details, please download the document or contact us.

The STEM device equipped with a Cs collector (spherical aberration correction function) enables ultra-high-resolution observation (resolution of 0.10 nm). The HAADF*-STEM image, which is sensitive to atomic weight, is an effective tool for directly understanding multi-component crystal structures. In this study, we evaluated micro-particles in oxide semiconductors, which can be applied to the atomic arrangement at heterogeneous material interfaces and compound interfaces, as well as grain boundary segregation assessments. *High-Angle Annular Dark-Field: Contrast is obtained that is proportional to atomic weight (Z).

When materials undergo chemical reactions and phase changes with increasing temperature, performing XRD measurements while heating is effective. We present a case where high-temperature XRD measurements were used to identify the decomposition products of copper(II) sulfate pentahydrate. The results showed that the diffraction peaks changed at the temperature where decomposition occurred, clearly confirming the changes in the crystal structure. In MST, it is possible to conduct Out-of-plane XRD measurements and In-plane XRD measurements while heating.

For the sample where Pt was sputter-deposited on a Si substrate, Out-of-plane XRD and In-plane XRD measurements were conducted while increasing the temperature. In both measurements, it was observed that the peak intensity of Pt(111) increased and the full width at half maximum decreased at temperatures above 500°C, indicating that crystallization was progressing. Additionally, it was confirmed that as the temperature rose, thermal expansion caused the peaks to shift towards lower angles (the direction of increased lattice spacing).

The WA (Wafer Analyzer) is a device that heats wafers with a diameter of φ76 to 300mm to elevate their temperature, gasifying organic contaminants adhered to the wafer surface and trapping them in a collection tube. As a result, it can concentrate compounds such as phthalate esters and cyclic siloxanes, which are considered causes of device characteristic impacts and manufacturing troubles, allowing for high-sensitivity measurement using GC/MS. Quantification using hexadecane is also possible. - Evaluation of organic contaminants on one side of the wafer is possible. - Detection of easily volatile components is possible since vacuum pumping is not required. - Organic components can be detected with high sensitivity (for 300mm wafers, on the order of 0.01ng/cm²). - Quantification using hexadecane conversion is possible.

TDS is a method that heats samples in high vacuum (1E-7 Pa) and detects the gases that are released. By heating the sample at a constant rate in high vacuum, it is possible to confirm the temperature dependence of even trace amounts of desorption (at the monolayer level). Additionally, for some components, it is also possible to calculate the number of molecules of the desorbed gas. We will introduce examples of TDS applied to representative materials.

Soft X-ray emission spectroscopy (SXES) using synchrotron radiation is widely used as a method to evaluate the electronic states of materials because it allows for the direct acquisition of the partial density of states (pDOS) near the Fermi level for each element constituting the material. Furthermore, the characteristics of this method include: 1. Information from the bulk can be obtained, 2. It can be evaluated without being affected by charging effects even for insulators, and 3. It has a low detection limit (less than 1 atomic %), making it particularly effective for evaluating materials containing light elements (such as B, C, N, O). In this document, we will introduce the SXES spectrum of a GaN substrate as a measurement example.

Understanding the band structure, including valence bands, conduction bands, and gap states, is an extremely important evaluation criterion for controlling various properties of materials. However, there are limited analytical methods available for direct and detailed assessment of these aspects. Simultaneous measurements of X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) using synchrotron radiation allow for a comprehensive understanding of the band structure, as well as detailed information regarding the attribution of the elements and orbitals that compose it. This document presents the XAS and XES spectra of GaN substrates as an example of measurement.

The SIMS analysis profile of the interface between different materials changes with a certain width in the depth direction. This is due to the characteristics of SIMS analysis, which are influenced by ion beam mixing and the roughness of the sputtered surface. The detected impurities represent averaged information up to the mixed depth, detecting ions from regions with a width in the depth direction. Therefore, the interface position is generally defined as the location where the ion intensity of the main constituent elements reaches 50%.

In clean rooms where the manufacturing of semiconductors and liquid crystals takes place, it is important to monitor not only particles but also molecular-level chemical contamination (molecular contamination). Floating molecular contaminants include acidic and basic gases, cohesive organic substances, dopants, and metals, and the analysis methods vary depending on the components. Here, we will introduce details about cohesive organic substances and the representative collection methods, "adsorbent collection" and "wafer exposure collection."

When designing and controlling the properties of various materials, it is very important to clarify the types and amounts of elements present in trace amounts in the base material, as well as their states of existence. The types and amounts of elements can be evaluated using methods such as SIMS (Secondary Ion Mass Spectrometry) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry), but the evaluation of states of existence, such as valence and chemical bonding states, is effectively conducted using XAFS (X-ray Absorption Fine Structure) measurements with synchrotron radiation. This document introduces a case study where the valence of trace amounts of Ce in ceramic materials was evaluated as a measurement example.

AFM is a method that scans the surface of a sample with a fine probe and measures nano-scale surface topography in three dimensions. It can measure a wide range of materials, not only for the evaluation of metals, semiconductors, and oxides, but also for soft materials such as hair and contact lenses. This document presents various AFM images of different materials.

XPS is a method for evaluating the composition and bonding state of a material based on the photoelectron spectrum from inner shell levels. On the other hand, the valence band spectrum, which reflects the states of the outer shell electrons, appears near the Fermi level. This document presents a case study that verifies the reduction treatment of Sn oxides by comparing and discussing the density of states calculated through first-principles calculations with the valence band spectrum obtained by XPS. Utilizing computational simulations allows for a deeper understanding of the XPS spectrum obtained.

By measuring the sample, it is possible to evaluate the crystal structure through the combination of results obtained and simulations. This document introduces a case study in which the crystal structure is discussed by comparing the results obtained from HAADF-STEM and EDX measurements on polycrystalline neodymium magnets with simulated images using the respective measurement conditions. The combination of measurement results and computational simulation results allows for a deeper understanding of the crystal structure.

β-Ga2O3 has a wide band gap and is expected to be a promising material for next-generation power devices and oxide semiconductors in terms of excellent power transmission efficiency and cost reduction. In recent years, it has been reported that β-Ga2O3 can be n-doped with Si or Sn. In this study, we conducted structural optimization calculations for models of β-Ga2O3 doped with Si or Sn and evaluated which sites each dopant is more likely to occupy in the crystal. Subsequently, we calculated the density of states from the obtained structural models and investigated the changes in electronic states due to doping.

Rietveld analysis is a method for analyzing measurement data from XRD (X-ray diffraction) and neutron diffraction. In addition to identifying lattice constants and space groups using existing methods, it is possible to obtain more detailed crystallographic information, such as atomic arrangements within the unit cell, if there is a crystal structure model (candidate) for the sample.

We have launched a new service using Glow Discharge Mass Spectrometry (GDMS) starting from May 15 (Monday). - Simultaneous analysis of over 70 elements, from major components to trace components at the ppb level, is possible. - Detection of C, N, and O at the ppm level, which was previously difficult. - Depth direction analysis is possible from nm to several tens of µm.

Soft X-ray emission spectroscopy (SXES) using synchrotron radiation is widely used as a method to evaluate the electronic states of materials, as it allows for the direct acquisition of the partial density of states (pDOS) near the Fermi level for each element constituting the material. Furthermore, the characteristics of this method include: 1. Information from the bulk can be obtained. 2. It can be evaluated without being affected by charging effects, even for insulators. 3. The detection limit is low (<1 atomic%). These features make it particularly effective for evaluating materials containing light elements (such as B, C, N, O). In this document, we will introduce the SXES spectrum of a GaN substrate as a measurement example.

IGZO thin films, which are transparent oxide semiconductors, are being researched and developed as TFT materials for displays. IGZO is a material whose properties change based on the composition of the thin film and the amount of impurities within it, making it important to obtain information about the composition and impurities. This time, we will introduce a case where the main components and the amounts of metallic impurity elements in IGZO powder, the raw material for the thin film, were evaluated with high precision using ICP-MS. Analysis is possible not only for powders but also for bulk and thin films.

High-resolution HAADF-STEM images reflect the atomic arrangement of crystals, and by simulating STEM images corresponding to various crystal orientations, they help in accurately understanding the relative orientations between crystal grains and the observed images in polycrystalline materials. This document presents a case where STEM images were simulated from the crystal orientation information obtained by the EBSD method for the crystal grains in a polycrystalline neodymium magnet, and compares them with actual high-resolution HAADF-STEM images.

Tin (Sn), such as in solder, is used in many electronic components. In the XPS analysis of the Sn surface, by using the 4d orbitals in addition to the quantitative and state analysis typically performed with the 3d orbitals, it is possible to separate the oxidation states (divalent Sn2+ (SnO) and tetravalent Sn4+ (SnO2)) and calculate their ratios. Furthermore, by examining the valence band, it is possible to sensitively detect even a very small amount of the low oxidation state (divalent Sn2+ (SnO)). This document presents examples of evaluating Sn on the surface of solder using various orbitals.

Impurities from components of the film formation device, target materials, and plating solutions can contaminate the device and have adverse effects, making the qualitative assessment of impurities on surfaces, within films, and at interfaces important. TOF-SIMS can sensitively evaluate unknown elements present on surfaces, within films, and at interfaces in a single measurement due to the following three characteristics: 1. For metallic elements, ions from m/z 1 to 800 can be detected simultaneously in one measurement. 2. Detection sensitivity of a few ppm can be achieved (varies depending on materials and ions). 3. The use of a sputter gun allows for the evaluation of depth distribution.