Effective Method for Decreasing Detection Limit of Dopant Concentration in Semiconductor Using Dual SDD Analysis System
An energy dispersive spectrometer (EDS) analysis system using a Si drift detector (SDD) can perform a highly sensitive elemental analysis due to its flexibilities of detector shape and size and high speed processing. In addition, the use of multiple SDD sensors can dramatically enlarge the effective area of the detector, which should shorten the measurement period while increasing detection sensitivity. Up to now, transmission electron microscopy (TEM)-EDS has not been greatly used in the analysis of elements in semiconductor doping. This is because the limit of detection (LOD) by Si(Li)-EDS is of the order of 1500-2000 ppm, which is a level of performance insufficient for dopant analysis in semiconductor industry. There has consequently been a strong desire to determine just how small an amount of elements can be detected (detection limit) using an analysis system with two SDDs. Theoretical estimation of LOD is determined with competition between the net counts for dopant element and the fluctuation of background tail of Si peak at the dopant peak energy [1]. When we measure the net counts of dopant element is three times larger than the fluctuation (sigma) of the background, it confirms the presence of the dopant with 99.7% certainty. Thus, we define a dopant concentration (Cdopant) at LOD as
Concentration at Detection Limit of Dopant for Semiconductor Samples Using Dual SDD Analysis System
Yokohama, 221-0022, Japan An energy dispersive spectrometer (EDS) analysis system using a Si drift detector (SDD) can enhance sensitivity of compositional analysis by using a large solid angle detector [1,2]. The use of multiple EDS detector system dramatically enlarge the effective area of the detector, resulting in the short measurement period. Up to now, transmission electron microscopy (TEM)-EDS has not been greatly used in the analysis of elements for semiconductor doping. This is because the detection limit by Si (Li) - EDS is of the order of 1500-2000 ppm, which is insufficient for semiconductor industry. There has consequently been a strong desire to see “limit of detection (LOD)”, that is, how small an amount of elements we can be detected, using a multiple SDD analysis system. In this study, we explore the concentration at LOD for As dopant in Si device using FETEM with a dual SDD analysis system. We used an As-doped Si wafer as a sample. The depth profile of As concentration in the Si wafer has been verified by Secondary Ion Mass Spectrometry (SIMS). We made a cross sectional lamella sample for TEM observation using an ion milling (Ion Slicer EM-09100IS, JEOL). The thickness of the TEM sample is estimated to be 140 nm judging from the count rate of X-ray and probe current. We measured several data sets of EDS spectrum imaging using a 200kV FETEM (JEM-2800 JEOL) equipped with two SDD detectors (sensor area = 100 mm 2 ). The concentration profiles were extracted and converted from the data set with a quantitative analysis system (NSS 3, Thermo Fisher Scientific). Figure 1 shows
A LITERATURE REIEW OF TARGET COSTING IN SSCI AND SCI&SCI-EXPANDED INDEXES
Target costing as a cost management and profit planning system is used by many competitive firms since 1970s. Although the concept is simple, the implementation needs an extensive collaboration inside and outside of the organization. In contrast, many organization managers think that target costing is just related with accounting and finance staff. Our study aims to review the literature of this important concept; target costing by examining 41 English articles published in SSCI and SCI&SCI-Expanded between 1985-2008. The study aims to briefly explain the content of each article to show the reader what has accomplished so far.