Thermal Stability, Adhesion and Electrical Studies on (Ti,Zr)Nx Thin Films as Low Resistive Diffusion Barriers between Cu and Si

Cheng-Lin Huang,Chih-Huang Lai,Po-Hao Tsai,Yu-Lin Kuo,Jing-Cheng Lin,Chiapyng Lee 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.3

In this study, we investigated the thermal stability, wettability, adhesion and reliability of (Ti,Zr)Nx films used as the diffusion barrier between Cu and Si. (Ti,Zr)Nx films were prepared by DC reactive magnetron sputtering from a Ti-5 at. % Zr alloy target in N2/Ar gas mixtures. A minimum film resistivity of 59.3 μΩ cm was obtained at an N2/Ar flow ratio of 2.75, which corresponds to the near stoichiometric composition (N/(Ti,Zr) ratio ~0.95). The sheet resistance of Cu/(Ti,Zr)N0.95/Si was not significantly increased until annealing above 750°C, indicating good thermal stability. On the other hand, the adhesion energy between Cu and the (Ti,Zr)Nx film was reduced as the N/Ti ratio was increased. To obtain reliable performance on stress-induced-voiding (SIV) and electromigration (EM) tests, we proposed to use (Ti,Zr)/(Ti,Zr)Nx/(Ti,Zr) tri-layers. We suggest that the interfacial adhesion between barrier and Cu plays an important role in reliability. The proposed tri-layer structure may be a promising candidate for a barrier, as it exhibits excellent reliability without increasing resistance.

Mesenchymal Stem Cell Secreted-Extracellular Vesicles are Involved in Chondrocyte Production and Reduce Adipogenesis during Stem Cell Differentiation

Tsai Yu-Chen,Cheng Tai-Shan,Liao Hsiu-Jung,Chuang Ming-Hsi,Chen Hui-Ting,Chen Chun-Hung,Zhang Kai-Ling,Chang Chih-Hung,Lin Po-Cheng,Huang Chi-Ying F. 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND: Extracellular vesicles (EVs) are derived from internal cellular compartments, and have potential as a diagnostic and therapeutic tool in degenerative disease associated with aging. Mesenchymal stem cells (MSCs) have become a promising tool for functional EVs production. This study investigated the efficacy of EVs and its effect on differentiation capacity. METHODS: The characteristics of MSCs were evaluated by flow cytometry and stem cell differentiation analysis, and a production mode of functional EVs was scaled from MSCs. The concentration and size of EVs were quantitated by Nanoparticle Tracking Analysis (NTA). Western blot analysis was used to assess the protein expression of exosomespecific markers. The effects of MSC-derived EVs were assessed by chondrogenic and adipogenic differentiation analyses and histological observation. RESULTS: The range of the particle size of adipose-derived stem cells (ADSCs)- and Wharton’s jelly -MSCs-derived EVs were from 130 to 150 nm as measured by NTA, which showed positive expression of exosomal markers. The chondrogenic induction ability was weakened in the absence of EVs in vitro. Interestingly, after EV administration, type II collagen, a major component in the cartilage extracellular matrix, was upregulated compared to the EV-free condition. Moreover, EVs decreased the lipid accumulation rate during adipogenic induction. CONCLUSION: The results indicated that the production model could facilitate production of effective EVs and further demonstrated the role of MSC-derived EVs in cell differentiation. MSC-derived EVs could be successfully used in cell-free therapy to guide chondrogenic differentiation of ADSC for future clinical applications in cartilage regeneration.

Percutaneous Endoscopic Interbody Debridement and Fusion for Pyogenic Lumbar Spondylodiskitis: Surgical Technique and the Comparison With Percutaneous Endoscopic Drainage and Debridement

Po-Ju Lai,Sheng-Fen Wang,Tsung-Ting Tsai,Yun-Da Li,Ping-Yeh Chiu,Ming-Kai Hsieh,Fu-Cheng Kao 대한척추신경외과학회 2021 Neurospine Vol.18 No.4

Objective: Surgical treatment of severe infectious spondylodiskitis remains challenging. Although minimally invasive percutaneous endoscopic drainage and debridement (PEDD) may yield good results in complicated cases, outcomes of patients with extensive structural damage and mechanical instability may be unsatisfactory. To address severe infectious spondylodiskitis, we have developed a surgical technique called percutaneous endoscopic interbody debridement and fusion (PEIDF), which comprises endoscopic debridement, bone-graft interbody fusion, and percutaneous posterior instrumentation. Methods: Outcomes of PEIDF in 12 patients and PEDD in 15 patients with infectious spondylodiskitis from April 2014 to July 2018 were reviewed retrospectively. Outcome were compared between 2 kinds of surgical procedures. Results: Patients in PEIDF group had significantly lower rate of revision surgery (8.3% vs. 58.3%), better kyphosis angle (-5.73°±8.74 vs. 1.07°±2.70 in postoperative; 7.09°±7.23 vs. 0.79°±4.08 in kyphosis correction at 1 year), and higher fusion rate (83.3% vs. 46.7%) than those who received PEDD. Conclusion: PEIDF is an effective approach for treating infectious spondylodiskitis, especially in patients with spinal instability and multiple medical comorbidities.

Characteristics of Reactively Sputtered Niobium Nitride Thin Films as Diffusion Barriers for Cu Metallization

Cheng-Lin Huang,Chih-Huang Lai,Po-Hao Tsai,Hsing-An Huang,Jing-Cheng Lin,Chiapyng Lee 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5

NbN films were prepared by radio frequency reactive magnetron sputtering and then employed as diffusion barriers between Cu and Si. The microstructure of the NbN films was an assembly of very small columnar crystallites with a cubic structure. To investigate the properties as diffusion barriers, we performed metallurgical reactions of Cu/NbN0.8/Si, Cu/Nb/Si and Cu/TaN0.7/Si for comparisons. The sheet resistance increased dramatically after annealing above 750°C for Cu/NbN0.80/Si, and above 500°C for both Cu/Nb/Si and Cu/TaN0.7/Si. The interfaces were deteriorated seriously and formation of Cu3Si was observed when the sheet resistance was significantly increased. The diffusion coefficient of Cu in NbN barrier films was estimated by using the change of resistance (ΔRs/Rs %). Compared with TaN0.7, NbN0.8 films possess larger grain size and lower Cu diffusion coefficient. Our results suggest that the NbN film can be used as a diffusion barrier for Cu metallization as compared to the well-known TaN film.

Correlation Between Fiber Orientation and Geometrical Shrinkage of Injected Parts Under the Influence of Flow-Fiber Coupling Effect

Chao-Tsai Huang,Jun-Zheng Wang,Cheng-Hong Lai,Sheng-Jye Hwang,Po-Wei Huang,Hsin-Shu Peng 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4

Fiber reinforced thermoplastics (FRP) have been widely used in automotive industry. However, how does the flow-fiber coupling effect influence the micro fiber orientation and further affect the geometrical shrinkage of the final part that is not fully understood yet. In this study, a complex center-gated plate has been applied to study the influence of the flow-fiber coupling effect on the fiber orientation variation and the geometrical change through numerical simulation. Then the practical verification through the micro-computed tomography (micro-CT) and image processing technology was carried out. Results show that in the presence of the flow-fiber coupling the required spruce pressure will be higher compared to no coupling case. In addition, the melt flow front pattern will be changed from “convex-flat” to “convex-concave” under the influence of this coupling. Moreover, in the presence of the flow-fiber coupling effect, the wider core width for fiber orientation tensor in the flow direction (A11) can be obtained from upstream to downstream regions for the same model. However, in the downstream region (i.e. in the FR), the flow-fiber coupling effect is more significantly due to the action of less shear rate in that region. Finally, through the measurement of the left–right asymmetrical shape of the FR for Model I (or Model II), the reason is that the flow-fiber coupling effect will switch the fiber orientation from the flow direction (A11) dominate to the cross-flow direction (A22) dominate. This asymmetrical fiber orientation distribution will further create that asymmetrical shrinkage shape of final part. The correlation between fiber orientation and geometrical shrinkage can be achieved.

Mathematical model of S-shaped gear surface

Hsueh-Cheng Yang,Po-Yi Tsai 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.7

In this study, an imaginary S-shaped surface rack cutter was used to create a gear pair with S-shaped surface. First, a mathematical model of the imaginary S-shaped surface rack cutter was constructed by using the geometry. Then, a family of the imaginary rack cutter surfaces was obtained through the homogeneous coordinate transformation matrix. The equation of meshing was calculated by using differential geometry. A mathematical model for the S-shaped surface gear pair was determined by substituting the equation of meshing into the family of imaginary rack-cutter surfaces. The kinematic errors of the gear pair were calculated by setting the assembly error and using tooth contact analysis. Contact between the gear and the pinion was simulated by using the interference function of a computer-aided design software package. To investigate the real contact between the pinion and the gear, a rapid prototype machine was used to manufacture a real gear pair. Three of the teeth on the real gear were coated with dyes. After running the gear for long time, the dyes on the teeth were scraped and rubbed, and they were evenly rolled over the teeth.

The Interaction of Oxytocin and Social Support, Loneliness, and Cortisol Level in Major Depression

Tsung-Yu Tsai,Huai-Hsuan Tseng,Mei Hung Chi,Hui Hua Chang,Cheng-Kuan Wu,Yen Kuang Yang,Po See Chen 대한정신약물학회 2019 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.17 No.4

Objective: Loneliness is a specific risk factor for depressive symptoms and suicidal behavior. The present study examined whether the serum oxytocin level would interact with social support and buffers loneliness and hypothalamic-pituitary- adrenal (HPA)-axis activity in drug-naïve patients with major depressive disorder (MDD). Methods: Twenty-six patients with MDD (male:female = 3:23; mean age, 45.54 ± 12.97 years) were recruited. The 17-item Hamilton Depression Rating Scale, UCLA Loneliness Scale and self-reported Measurement of Support Function Questionnaire were administered. Serum oxytocin and cortisol levels were assessed using a commercial immunoassay kits. Results: In MDD patients, a negative association was found between degrees of social support and loneliness ( = −0.39, p = 0.04). The interaction between social support and serum oxytocin level was negatively associated with loneliness ( = −0.50, p = 0.017) and serum cortisol level ( = −0.55, p = 0.020) after adjusting for age. Follow-up analyses showed that the association between higher social support and lower loneliness was observed only in the higher-oxytocin group (r = −0.75, p = 0.003) but not in the lower group (r = −0.19, p = 0.53). The significance remained after further adjusting for sex and depression severity. Conclusion: Low oxytocin level is a vulnerability factor for the buffering effect of social support for loneliness and aberrant HPA-axis activity in MDD patients.

Predicting load on ground anchor using a metaheuristic optimized least squares support vector regression model: a Taiwan case study

Min-Yuan Cheng,Minh-Tu Cao,Po-Kun Tsai 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.1

Failure of ground anchor is a major cause of landslides and severe natural hazards, especially in the highly developed mountainous areas such as New Taipei City. Accurately estimating load on ground anchors is thus essential for evaluating the stability status of slope to prevent landslide from happening. This study first employed correlation analyses to identify possible influential factors of load on ground anchors. Second, various artificial intelligence models were used to map the relationship of the found influencing factors with the current load on ground anchors. The results indicated that the symbiotic organisms search-optimized least squares support vector regression (SOS-LSSVR) model had the optimal accuracy by earning the smallest value of mean absolute percentage error (9.10%) and the most outstanding value of correlation coefficient (R = 0.988). The study applied the established inference model for the real case of estimating load on un-monitoring ground anchors. The analyzed results strongly advised administrators to conduct site surveying and patrolling more frequently to take early proper actions. In summary, the obtained results have demonstrated SOS-LSSVR as an effective alternative for the conventional subjective evaluation methods, which is able to rapidly provide accurate values of load on un-monitoring ground anchors.

An Improved Frequency and Voltage Restoration Method of the Droop Controls for Power Converters

Meng-jiang Tsai,Po-tai Cheng 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper investigates the conventional droop control and the recently-developed droop control, like virtual synchronous machine (VSM) based control and Q−V control. The VSM based control can effectively smooth frequency dynamics by emulating the damping and the inertia of the synchronous machine, and Q−V droop control can enhance the more ideal results in the reactive power sharing among converters. Both controls bring their frequency and V to the initial values depending on the restoration mechanism. Such a mechanism is achieved by deviating their power reference, and it may lead to severe nonideal power-sharing when the converters asynchronously connect with the system. To improve this problem, this study presents a resetting mechanism realized through a central console. In the end, the laboratory test results are supported to validate their benefits.

Circulating Current Reduction of Parallel Connected Four-Pole Inverters

Meng-Jiang Tsai,Po-Tai Cheng 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Connecting the four-pole inverters (FPIs) in parallel has many benefits, like lower cost, high flexibility and excellent reliability, and becomes a favorite option in industry. However, such side effects of parallel connection as the circulating current will lead to severe distortion and extra loss. The circulating current is mainly caused by the difference of common mode voltage (CMV) and closely associated with switching states. The zero states contain extremes of CMV levels, which aims to significantly affect the circulating current. This paper presents a three-dimensional pulse width modulation (3-D PWM) approach adapted to the parallel connected FPIs. The 3-D modulation scheme substituting the zero states with active states is socalled three-dimensional active zero state PWM (3-D AZSPWM) and based classical 3-D space vector PWM (3-D SVPWM), possessing low current distortion and high dc-link utilization characteristic. By synthesizing output references without zero states, both CMV levels and circulating current can be suppressed in effect. Based on a two-module parallel connected system, the simplified model is made to discuss the phenomenon of circulating current. Besides, the simulation and test results are presented to validate the performance of 3-D PWM in balanced and unbalanced condition respectively.