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

In the quantitative and compositional evaluation of impurities in the semiconductor material SiGe using SIMS, the following considerations must be taken into account during analysis: ● If appropriate quantification corrections are not made according to the Ge concentration, the impurity quantification values may differ by more than 50% from the actual values. Standard samples corresponding to each composition are necessary for quantitative evaluation. ● It is known that the sputtering rates differ between Si and SiGe. In samples where the composition varies with depth, the sputtering rate changes with depth as well. At MST, high-precision compositional analysis is possible through the preparation of standard samples. Additionally, by using calibration curves, impurity analysis and sputtering rate corrections for each composition of SiGe can be performed.

If you want to qualitatively evaluate metallic foreign substances, analyzing only the very surface may result in information about the oxide film present on the surface of the foreign substance, and you may not obtain information about the foreign substance itself. By performing depth analysis using TOF-SIMS, it is possible to evaluate the composition and state of the foreign substance located deeper than the oxide film. This document presents case studies evaluating the state of three locations that are believed to contain aluminum-based foreign substances.

In the fabrication of Si-based semiconductor devices, various processes such as ion implantation and annealing are performed. It is considered important to confirm the degree of irradiation defects and the extent of crystallinity recovery before and after these processes in order to control the manufacturing process. Photoluminescence (PL) measurements at low temperatures are one effective means of investigating these aspects. An example of PL measurements of samples that underwent ion implantation on a Si substrate followed by annealing treatment is presented.

In the field of semiconductors and their manufacturing processes, it is considered important to control inorganic and organic substances present in the environment. At MST, it is possible to collect components from the indoor atmosphere using the impinger collection method and analyze the types and quantities of corrosive components in the atmosphere. This time, we will introduce a case analyzed using the impinger collection-ion chromatography method.

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).

■Measurement Method for Depth Direction Distribution (1) Limitations of Depth Direction Resolution in Oblique Incidence Method The dependence of depth direction resolution on primary ion energy in the oblique incidence method was investigated using δ-doped samples (Figure 1). It was found that in the oblique incidence method, there is a limit to the improvement of depth direction resolution due to the roughness of the crater bottom (Figure 2). (2) Improvement of Depth Direction Resolution by Vertical Incidence Method Figure 3 shows the relationship between the half-width of the B peak (δ-doped sample) and primary ion energy in both vertical and oblique incidence methods. In the region below 1 keV of primary ion energy, where there were limitations in improving resolution with the oblique incidence method, improvements in resolution have been achieved with the vertical incidence method.

Measurements can be performed in bulk state without the need for thinning processes like TEM (NBD: Nano Beam Diffraction). It has the high spatial resolution characteristic of SEM and relatively high strain sensitivity. Additionally, there is a possibility of detecting local lattice strain as tensor data.

It is possible to non-destructively determine the interstitial oxygen and carbon atom concentrations in silicon single crystals using FT-IR analysis. The concentrations are calculated from the peak heights of the absorption due to interstitial oxygen or carbon in the spectra measured by the transmission method. The calculation method is standardized by the Japan Electronics and Information Technology Industries Association (JEITA). Below are examples of calculated interstitial oxygen atom concentrations.

By conducting sample pretreatment, transportation, and measurement under a high-purity inert gas atmosphere, it is possible to evaluate while suppressing surface oxidation and moisture adsorption. ■Examples of Application - Semiconductor electrode materials Evaluation of peeling surfaces can be conducted while minimizing the effects of secondary contamination and oxidation. - Organic EL materials Working in an inert gas atmosphere from the moment of opening prevents material degradation. - Battery materials such as Li If processing in a N2 atmosphere is not possible for materials like Li, treatment can be performed in an Ar atmosphere as an alternative.

In the method for preparing thin film samples for TEM observation using FIB, high-energy Ga ions (acceleration voltage of 30 kV) are used, resulting in the formation of a damage layer on the processed surface, which causes a deterioration in the image quality of the TEM. By performing processing at a lower acceleration (2 kV) than conventional methods, the damage layer can be reduced, leading to improved image quality. By reducing the damage on the FIB processed surface through low-acceleration FIB processing, high-quality and reliable data can be obtained in TEM image observation and EELS measurements.

When analyzing and identifying unknown samples such as foreign substances, it is effective to analyze the data comprehensively from multiple measurement methods. We will introduce a case where FT-IR analysis, which is a vibrational spectroscopy method, was combined with XRF analysis, an elemental analysis method in the atmosphere, to identify two types of white powders.

It is possible to evaluate the distribution of nitrogen in SiON films in the depth direction, even down to low concentration areas where high-sensitivity SIMS analysis excels, and to assess the amount of nitrogen (unit: atoms/cm²) with high precision (Figure 1). Additionally, nitrogen can be converted to atomic% (Figure 2), and a fitting curve for nitrogen can be calculated, allowing for the determination of nitrogen's peak concentration, depth, and half-width through fitting (Figure 3).

The concentration distribution of boron (B) in silicon (Si), which significantly affects the characteristics of device design, can be evaluated with high sensitivity and high depth resolution through SIMS analysis. However, it has been found that under general analysis conditions, distortions occur in the concentration distribution of B due to measurement-related factors. In MST, it has been confirmed that sample cooling is effective for correcting these distortions, enabling a more accurate evaluation of the concentration distribution.

It is possible to observe in detail from an overview of the NPN bipolar transistors within commercially available LSI to an enlarged view of the emitter section. This is an example where a cross-section passing through the center of the emitter electrode was exposed, and AFM observation and SCM measurement were conducted. By overlaying the AFM image, the positional relationship with the wiring becomes clear.

By using a Cs-corrected TEM device that compensates for spherical aberration, it is possible to observe the cross-sectional structure of devices with high resolution. This case presents data from high-resolution (HR)-TEM observation and EDX elemental distribution analysis of commercially available MPU transistor components. Even for fine multilayer structures like FinFETs, it is possible to clearly observe the structure and elemental distribution of the devices using a Cs-corrected TEM.

In AES analysis, it is possible to evaluate the elemental composition of the surface of minute foreign substances, making it useful for foreign substance analysis in small areas. However, due to the effects of damage from electron beams and other sources, there is a possibility that the foreign substances may change or disappear. Particularly when halogen elements are involved, the impact can be significant, and caution is required. An example of a case where a foreign substance disappeared during SEM observation or AES measurement is shown, specifically regarding NaCl particles on a Si wafer, along with the results of the AES analysis.

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.

We will extract small pieces from the wafer chip without breaking it and thin them down for high-resolution TEM observation and analysis. Furthermore, by cutting and preparing samples while leaving the areas to be analyzed, we will conduct TEM observation and analysis of the target areas from any desired direction and provide the data. Through advanced TEM sample preparation techniques, we will meet various observation, analysis, and evaluation needs.

The detection sensitivity in SIMS analysis depends on the amount of sputtered sample per unit time. Depending on the element, significantly improved sensitivity can be achieved by limiting the impurities to one element, allowing evaluation down to ppt (parts per trillion) levels of less than 5E13 atoms/cm3, which is effective for assessing low-concentration impurities in IGBT devices and high-purity wafers. This document presents examples of ultra-high sensitivity evaluations of low-concentration impurities in silicon.

We conducted three-dimensional imaging SIMS measurements of commercial MEMS products for B and As (measurement area: 75μm square, depth: approximately 1.5μm). After data processing, it is possible to extract surface distributions at arbitrary cross-sections and depths, depth direction distributions in arbitrary areas, and line profiles at arbitrary locations. Note: Since the sample is being excavated with an ion beam while capturing images in the depth direction, this constitutes destructive analysis.

■Principle HAADF-STEM (High-angle Annular Dark Field Scanning TEM) images are obtained by scanning a finely focused electron beam across the sample and detecting the electrons that are scattered at high angles using an annular detector. ■Features Materials with a larger Z2ρ scatter more at high angles ↓ Heavy elements appear dark in STEM images and bright in HAADF-STEM images. Since contrast is obtained that is proportional to atomic number (Z), it is also referred to as Z-contrast imaging.

By overlaying the luminescent image and the IR image, it is possible to identify leak locations under microscopic observation. If there are large-scale appearance anomalies such as cracks or electrostatic breakdown, abnormalities can also be confirmed with an IR microscope. Additionally, if luminescence cannot be detected due to light shielding of the emitter electrode, the collector electrode is removed, and near-infrared light is detected from the collector side. An example is presented where a high-voltage power supply capable of applying up to 2000V is used to operate a power device with high voltage resistance and low leakage current, and the failure location is identified using an emission microscope.

It is possible to detect H, C, N, and O in semiconductor substrates at concentrations below 1 ppm (approximately 5E16 atoms/cm3) and F at concentrations below 1 ppb (approximately 5E13 atoms/cm3) using this method. Examples of measurements in actual FZ-Si (Figure 1) and the background levels of III-V semiconductors are presented (Table 2). In addition to III-V semiconductors, standard samples have been prepared for various materials such as metal films and insulating films, enabling highly sensitive quantitative analysis. This method is ideal for bulk analysis of various materials, including semiconductor substrates, and for evaluating the contamination of gas components during semiconductor processes.

In semiconductor device manufacturing, from the perspective of improving yield, it is necessary to enhance the cleanliness of the backside of the wafer and to remove substances that remain on the bevel area of the wafer. In this study, we conducted TOF-SIMS analysis of the bevel inclined surface to evaluate the distribution of contamination (Figure 2). Additionally, by comparing the mass spectra of the adhered substances with those of the normal area and the contamination source, we found that the adhered substances matched the metal (Cr) and organic components of the contamination source. TOF-SIMS can capture the contamination generation process in the bevel area (edge and inclined surface).

When measuring the distribution of alkali metals in SiO2 under general analytical conditions, it is known that changes occur in the depth profile concentration distribution due to influences such as the electric field caused by the measurement. In MST, by cooling the sample during SIMS measurements, we suppress changes in the concentration distribution of alkali metals and evaluate the concentration distribution with higher accuracy.

The HfZrOx film, which is attracting attention as a high-k material and ferroelectric, has its physical properties such as dielectric constant significantly affected by its crystal structure. Therefore, identifying the crystal structure and calculating the proportion of each crystal structure are important evaluation criteria. While these can typically be assessed using XRD and XAFS, combining these two methods can provide more detailed information, even in cases where detailed analysis is difficult with just one method. In this instance, we present a case of identifying the crystal structure of HfZrOx films and calculating the proportions of each crystal structure through combined analysis of XRD and XAFS.

TOF-SIMS allows for simultaneous elemental analysis and molecular information analysis of organic and inorganic substances through mass spectra obtained by locally analyzing specific areas, making it effective for evaluating foreign substances and micro-regions. This document summarizes examples of analysis in sub-micron order micro-regions. Samples that were sputter-processed with FIB on layered structures were measured using TOF-SIMS. Evaluation of sub-micron order micro-regions has been achieved.

To investigate the causes of solder delamination, it is effective to conduct component analysis of the solder and the substrate interface. TOF-SIMS is a suitable method for evaluating delaminated areas because it can simultaneously analyze elemental composition and molecular information of organic and inorganic substances, as well as perform imaging analysis. This document presents a case study analyzing the cross-section of a delaminated solder area, confirming the distribution of substrate components, resin components, and organic components other than resin.

The analysis results of TDS may show multiple components detected for a single mass-to-charge ratio (m/z). Even in such cases, it is possible to estimate the components desorbed by heating by measuring multiple masses and comparing the desorption patterns. Using the TDS analysis results of W films on Si substrates as an example, I will explain the estimation methods for water and ammonia (m/z=17), as well as organic substances and argon (m/z=40).

SEM-EDX analysis and AES analysis are suitable for simple investigations of discoloration and foreign substances on metal surfaces. However, when the discoloration or foreign substances are thin or small, AES analysis, which provides information from very shallow areas of the surface (about 4-5 nm), is effective. The AES equipment owned by MST can acquire SEM images, allowing AES analysis to be conducted while confirming the areas of interest using SEM images. In this case study, we will present data comparing the evaluation of discoloration on the Cu surface using AES analysis and SEM-EDX analysis. Additionally, we will also present the results of AES depth direction analysis.

With the miniaturization of circuits, the design and development of micro vias for interlayer connections require an understanding of the quality of filling. TOF-SIMS is an effective method for evaluating the results, as it can simultaneously perform elemental analysis and analyze molecular information of organic and inorganic substances, as well as enable image analysis. This document presents a case study analyzing a sample with Cu filled in vias of approximately 0.5μm in diameter on a Si substrate. The analysis of positive ion results confirmed the distribution of Cu and Si. Measurement method: TOF-SIMS Product fields: LSI, memory, electronic components Analysis objectives: Composition distribution evaluation, failure analysis, defect analysis For more details, please download the document or contact us.

XPS and AES are surface-sensitive analytical techniques widely used for evaluating sample surfaces, but by combining them with ion etching, depth profiling analysis becomes possible. When conducting depth profiling analysis, it is important to appropriately differentiate between XPS and AES according to the area to be measured and the material of the sample in order to perform analysis that aligns with the objectives. The characteristics of depth profiling analysis using XPS and AES will be compared using the analysis of SUS passive films as an example.

It is known that the adsorption of organic substances on the wafer surface can lead to various issues, such as the degradation of gate oxide film breakdown voltage. Therefore, as the miniaturization and high integration of semiconductor devices progress, it has become increasingly important to monitor not only inorganic substances but also trace amounts of organic substances. Here, we present a case where silicon wafers were stored in two types of wafer cases, and the organic contamination components adhered to the entire wafer surface were concentrated using a wafer analyzer and evaluated using GC/MS.

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.

Silicon dioxide (SiO2) is widely used in semiconductors as an insulating film, in FPD substrate materials, optical materials, and from medical devices to jewelry; however, conducting structural analysis on glass, which is amorphous, is very challenging. Focusing on the cyclic bonding of SiO2 in glass, Raman measurements were conducted. (Figure 1) In single crystal quartz, the spectrum in the glass state is significantly different, and phonon bands due to long-range order are observed. (Figures 2, 3)

In a STEM device equipped with a spherical aberration correction function (Cs corrector), high-resolution observation and high-sensitivity analysis at the atomic level are possible. The resolution is approximately 0.10 nm.

TOF-SIMS detects secondary ions originating from molecules and visualizes their distribution. By estimating the components derived from the ion species detected from abnormal areas, it is possible to investigate which process the anomaly occurred in. When abnormal areas (such as discoloration or adhesion) are found on wafers or products, conducting TOF-SIMS measurements can help distinguish whether the issue is due to watermarks from cleaning and drying, alterations in the base material, or contaminants from a different process, making it effective for identifying the causes of defects.

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).

AES analysis is a method for obtaining compositional information from the surface down to a depth of several nanometers, and it is an effective analysis for investigating the composition of contaminants and foreign substances that occur on the surface during the manufacturing process. Since it rarely detects information about the substrate or base material, it allows for a simple examination of only the abnormal areas, such as foreign substances, without preprocessing. Additionally, by conducting surface analysis, it is possible to obtain elemental distribution images. In this case study, we will present data evaluated using AES analysis regarding foreign substances present on a Si wafer.

AES analysis is a method for obtaining compositional information from the surface to a depth of several nanometers. By performing AES measurements on the cross-section of a sample to obtain elemental distribution images, it is possible to clearly evaluate the layered structure. In addition to evaluating layered structures and conducting elemental analysis of the inner walls of trenches and holes, combining mechanical processing and ion beam processing allows for the assessment of thin alloy layers and phenomena such as diffusion and segregation of elements. In this case, we will present data evaluated using AES analysis for a thin film deposited on a silicon substrate.

In general, to remove dirt, a cotton swab may be dipped in ethanol and used for wiping. When the surface of a Si wafer was wiped with a cotton swab dipped in ethanol, an analysis was conducted using TOF-SIMS to determine what was distributed on the surface. The Si wafer wiped with the cotton swab showed stains that were not visible under an optical microscope, and it was found that these were due to the cotton swab. TOF-SIMS is effective for analyzing stains that are not visible under an optical microscope and for cleaning residues.

The TDS analysis results regarding the SiN film on the Si substrate are presented. In the low-temperature range up to around 100°C, there is little desorption, indicating that there were few adsorbed components on the surface of the sample. On the other hand, as the temperature of the sample increases, it can be observed that m/z 2 (H2), m/z 18 (H2O), and m/z 27 (C2H3: organic fragment components) are being desorbed. TDS analysis conducted under high vacuum (1E-7 Pa) is effective for evaluating the adsorbed gas components on the film surface and trace gas components within the film.

If the plating film contains gas, it may cause defects such as peeling, blistering, and bubbles within the film. To investigate the gas contained in the plating film, TDS, which can measure the gas released by heating the sample in a high vacuum, is effective. The results of TDS analysis on a sample with Ni/Au plating on SUS material are presented. The release of H2, HCN, H2S, and HCl from the plating film was confirmed. Additionally, quantitative values were calculated.