Single core configurations of saturated core fault current limiter performance of laboratory test models

Economic growth with industrialization and urbanization lead to an extensive increase in power demand. It forced the utilities to add power generating facilities to cause the necessary demand-generation balance. The bulk power generating stations, mostly interconnected, with the penetration of distributed generation result in an enormous rise in the fault level of power networks. It necessitates for electrical utilities to control the fault current so that the existing switchgear can continue its services without up-gradation or replacement for reliable supply. The deployment of fault current limiter (FCL) at the distribution and transmission networks has been under investigation as a potential solution to the problem. A saturated core fault current limiter (SCFCL) technology is a smart, scalable, efficient, reliable, and commercially viable option to manage fault levels in existing and future MV/HV supply systems. This paper presents the comparative performance analysis of two single-core SCFCL topologies impressed with different core saturations. It has demonstrated that the single AC winding configuration needs more bias power for affecting the same current limiting performance with an acceptable steady-state voltage drop contribution. The fault state impedance has a transient nature, and the optimum bias selection is a critical design parameter in realizing the SCFCL applications.

Effects of cobalt deposition and pretreatment process on electrical properties of products

The preferable conditions for formation of high quality CoSi2 films and effect of process parameters on properties of products were investigated. The pretreatment should not only remove the natural oxide layer completely, but also could not damage Si substrate. The good static random access memory (SRAM) proportion of products is high when pretreatment thickness is 20 Å, reached 96.5%. The radio frequency (RF) bias power process parameter should also take an optimal value. When RF bias power is 150 W, the good SRAM proportion of products is greater than 98%. The 100 Å Co can just completely react with Si substrate after twice annealing (500℃ 30s and 750℃ 30s), and if it exceeds 100 Å, Co will be residual. Decreasing Co thickness leads to contact resistance (RC) increase whatever in N-well or P-well. The overall standby current (Isb) of product is least when Co thickness is 80 Å. Finally, the products achieved good electrical properties when Co thickness is 80 Å, pretreatment thickness is 20 Å and RF bias power is 150 W.

Anti-Racism Working Group

Institutions of higher education fail to address ongoing systemic racism within their classrooms, boardrooms, and commons when university personnel and students are not prepared to discuss racism and structural inequalities that exist within the campus community. To address this at a public, Predominantly White Institution (PWI), a group of students, staff, and faculty developed an action-oriented community to increase awareness and advocacy efforts against systemic and micro-level racism. Founded by faculty in the university’s BSW and MSW programs, the Anti-Racism Working Group (ARWG) is composed of faculty, staff, and students from multiple university departments. The goals of ARWG include education and awareness, and dialogue about race, ethnicity, bias, power, and privilege; cultivating interdisciplinary faculty and student relationships, and inspiring anti-racist actions. This paper discusses and disseminates research about ARWG’s inaugural year and early assessments of the program. Data includes responses from students who attended ARWG workshops and found them useful in their conceptualization and self-awareness around race, privilege, and taking anti-racist action. ARWG members benefited around three themes including skill development, relationship building, and the increased awareness and ability to engage in productive discussions around race, power, and privilege. We share these results with other universities and organizations to encourage the creation of similar programs and to facilitate learning from our experiences.

Dual-Frequency RF Impedance Matching Circuits for Semiconductor Plasma Etch Equipment

The change in electrode impedance of semiconductor equipment due to repetitive processes is a major issue that creates process drift. In the current plasma etch chamber with a dual-frequency power system, the high-powered radio frequency (RF) source contributes to the enhancement of the plasma density, and the low-frequency bias power at the bottom electrode is adopted to enhance the injected ion energy in the plasma. The impedance control of the top electrode in dual-frequency capacity coupled plasma limits the impedance matching capability of the RF matching system because it only considers the high-frequency RF source. To control the precise impedance in dual-frequency semiconductor equipment, independent impedance control is required for each frequency. In this study, the impedance corresponding to a specific frequency was independently controlled using L (inductor) and C (capacitor). A 60 MHz stop filter and VVC were used to control 2 MHz impedance at a specific point, and a 2 MHz stop filter and VVC were used to control 60 MHz impedance. In the case of 2 MHz impedance control, the 2 MHz impedance changed from 10.9−j893 to 0.3−j62 and the 60 MHz impedance did not change. When controlling the 60 MHz impedance, the 60 MHz impedance changed from 0.33 + j26.53 to 0.2 + j190 and the 2 MHz impedance did not change. The designed LC circuits cover the impedance of 60 and 2 MHz separately and are verified by the change in the capacitance of the vacuum variable capacitors implemented in the RF impedance matching system.

Ion-Enhanced Etching Characteristics of sp2-Rich Hydrogenated Amorphous Carbons in CF4 Plasmas and O2 Plasmas

The sp2-rich hydrogenated amorphous carbon (a-C:H) is widely adopted as hard masks in semiconductor-device fabrication processes. The ion-enhanced etch characteristics of sp2-rich a-C:H films on ion density and ion energy were investigated in CF4 plasmas and O2 plasmas in this work. The etch rate of sp2-rich a-C:H films in O2 plasmas increased linearly with ion density when no bias power was applied, while the fluorocarbon deposition was observed in CF4 plasmas instead of etching without bias power. The etch rate was found to be dependent on the half-order curve of ion energy in both CF4 plasmas and O2 plasmas when bias power was applied. An ion-enhanced etching model was suggested to fit the etch rates of a-C:H in CF4 plasmas and O2 plasmas. Then, the etch yield and the threshold energy for etching were determined based on this model from experimental etch rates in CF4 plasma and O2 plasma. The etch yield of 3.45 was observed in CF4 plasmas, while 12.3 was obtained in O2 plasmas, owing to the high reactivity of O radicals with carbon atoms. The threshold energy of 12 eV for a-C:H etching was obtained in O2 plasmas, while the high threshold energy of 156 eV was observed in CF4 plasmas. This high threshold energy is attributed to the formation of a fluorocarbon layer that protects the a-C:H films from ion-enhanced etching.