Workfunction Tuning of Molybdenum Gate by Nitrogen Incorporation (May 2006)

Due to the aggressive scaling of CMOS devices, it is necessary to provide a metal gate solution to replace the conventional process known as a self-aligned poly-silicon gate. Molybdenum (Mo) possesses several properties that make it attractive as a CMOS gate electrode material. In addition, Mo has been identified as a candidate for “single-metal / dual workfunction” technology, with the ability to tune the workfunction by the introduction of nitrogen. In this study, the correlation between workfunction of the Mo gate and the incorporation of nitrogen was investigated. The flat-band voltage shift was extracted from the obtained C-V Characteristic curves. Both reactive sputtering and ion implantation methods provided a negative shift in the C-V characteristics. The observed shift was greater for the ion implantation methods. These results indicate that a Mo-gate process with incorporation of nitrogen is a good candidate for replacing the self-aligned poly-silicon gate process

Development, fabrication, and characterization of a vertical-diffused MOS process for power RF applications

High power radio frequency (RF) applications have become important because of a growing demand from the wireless market. With their superior switching speed, power Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) have become one of the well-known technologies used in high power RF systems. The primary focus of this thesis work was the development, fabrication, and characterization of discrete Verticaldrain lateral-Diffused MOS (VDMOS) power transistors using an interdigitated source/gate design. Several types of high power devices were also presented for comparison to the VDMOS structure. This thesis describes the overall purpose and the objectives of the proposed project, and provides the methodology used to complete these objectives. This project supports a new development initiative of the project sponsor, Spectrum Devices, Inc., who has been working with RIT in power bipolar technologies over the last two years. The process steps to create a 50 V power VDMOS transistor structure were designed using Silvaco ATHENA (SUPREM-IV) process simulation. Typical power VDMOS transistor fabrication steps were used as a starting point with modifications to include Faraday and UIS implant steps to address certain parasitic effects. The Faraday shield implant was performed to shift the parasitic gate- field capacitance over to the input side of the device, which should dramatically improve the frequency response of the device. The UIS implant was used to reduce the parasitic BJT of a power VDMOS transistor. The implementation of the proposed structure also eliminated the need for an added masking operation for each implant step, and kept the structure self- aligned to the gate stack. This eliminated potential overlay tolerances and error that may be encountered in photolithography steps. The initial process parameters were carefully varied and adjusted to meet the target specifications (such as threshold voltage, breakdown voltage, gate oxide thickness, etc.) using ATHENA and ATLAS simulation software. After the device fabrication was completed, DC testing was performed on the fabricated VDMOS transistors both at RIT and at Spectrum Devices. A successful extraction of the transfer curves, family of curves, and breakdown voltage plots both in low and high current settings was achieved. The designed process produced a power VDMOS with a breakdown voltage of up to 180 V, a threshold voltage of ~3.8 V, a transconductance up to ~7 mhos, and an operating current of nearly 5 A. The experimental results were compared to the target specification provided by Spectrum Devices. In addition, impacts of the Faraday shield implant on the breakdown voltage and terminal capacitances of a VDMOS device were verified through DC testing. Preliminary wafer- level AC testing was performed and demonstrated the functional performance of the device up to 100 kHz frequency range. Although it would be interesting to see the impact of UIS implant step on a device performance, no AC test was yet to be performed. This work presented the first power VDMOS transistors successfully fabricated and characterized at RIT. With the data and information obtained from this thesis project, process modifications and adjustments should yield devices with improved performance

Two cases of lymphoepithelial cyst of the pancreas

A 35-year-old man was found to have a cystic mass in the pancreatic body on a routine health examination ; high serum CA19-9 was also detected. The enucleated cyst was diagnosed as a lymphoepithelial cyst (LEC). A 74-year-old man found to have a cystic mass in the pancreatic head by computer tomography as well as high serum CA19-9 was suspected of a cystic neoplasm of the pancreas (IPMN), and pylorus-preserving pancreaticoduodenectomy (PPPD) was performed. Pathologically, the cyst was found to be LEC. It is often difficult to diagnose pancreatic cyst as LEC preoperatively. Care should be taken not to do over-surgery for benign disease LEC

The Journal of Microelectronic Research

https://scholarworks.rit.edu/meec_archive/1015/thumbnail.jp

急性期虚血性脳卒中患者から機械的血栓回収術で得られた血栓の年齢と組成は血栓回収術転帰および臨床転帰と関連していた

Introduction: Understanding the composition of stroke thrombi retrieved by mechanical thrombectomy is essential to clarify the pathogenesis of stroke. However, it is difficult to evaluate thrombus composition precisely and objectively. Immunohistochemical staining was used to evaluate thrombus composition and age. Materials and methods: Consecutive thrombi (n = 108) retrieved from patients who underwent mechanical thrombectomy for acute large-vessel ischemic stroke were retrospectively analyzed. Lytic features of granulocytes and CD163 were estimated as indicators of the age of the cardioembolic (CE) thrombus. Results: The stroke subtypes were as follows: CE, 74 cases; large artery atherosclerosis, 11; undetermined etiology, 12; and other determined etiology, 11. There were no statistical differences in thrombi composition according to stroke subtypes. The fibrin area was positively correlated with the red blood cell (RBC) and platelet areas. The following analysis was performed using CE only. Regarding age, the thrombus was judged as fresh in 30.0 % and older in 70.0 % based on the lytic features. The RBC areas of older thrombi were smaller than those of fresh thrombi. The puncture-to-reperfusion time of older thrombi was longer than that of fresh thrombi. Platelet-rich thrombi were associated with a greater number of maneuvers, a smaller prevalence of TICI 3, and unfavorable functional outcomes compared to platelet-poor thrombi. The number of CD163 positive cells in thrombi with anticoagulants was higher than in those without anticoagulants. Conclusion: Thrombus composition correlated with revascularization and clinical outcomes. The composition of an acute ischemic thrombus may reflect the pathophysiology of stroke and influence treatment efficacy.博士（医学）・甲第855号・令和4年12月22日Copyright © 2022 Elsevier Ltd. All rights reserved

HSP70 and c-Fos expression of brain stem hypoglossal nucleus in drowning

The brain stem hypoglossal nucleus (HN) is the center of nerves innervating the upper respiratory tract and is related to control of mastication, deglutition, speech and respiration. To elucidate the relationship between asphyxia and the HN, we investigated the change of hypoglossal neurons in cases of hanging, strangulation, smothering, choking, drowning and respiratory failure. Using immunohistochemical techniques, we observed the brain stem HN with antibodies against microtubule-associated protein2(MAP2), muscarinic acetylcholine receptor (mAChR), c-fos gene product (c-Fos) and 72kD heat-shock protein (HSP70). MAP2, a cytoskeletal protein of the neuron, is a marker of neuronal damage. Muscarinic AChR was used as a marker of neuronal membrane and ACh signaling. We employed both HSP70 and c-Fos as markers of stress- or damage-related events. We measured the percentage of immunopositive neurons in total neurons of HN. Drowning produced higher expression of HSP70 and c-Fos than other causes of asphyxia, suggesting that drowning induces more severe damage in HN neurons. Furthermore, it was suspected that neuronal changes in drowning might relate to functions of the HN. These observations indicate that immunohistochemical examination of the brain stem HN could provide useful information for determining the cause of asphyxia

A surgical case of small intestinal anisakiasis with symptoms of ileus

We report a surgical case of intestinal anisakiasis in which we identified a complete larva. A 48-year-old man complaining of epigastralgia after eating roasted mackerel was admitted to the hospital with a diagnosis of ileus with peritonitis. Abdominal CT showed dilatation and partial thickening of the small intestine. An emergency operation was carried out. On laparotomy, severe stricture of the jejunum was revealed. The affected intestine was resected. A larva whose head was invading the mucosa was found in the resected portion of the jejunum, and we diagnosed the case as intestinal anisakiasis

A case of superior mesenteric artery syndrome after left hemicolectomy for descending colon cancer

A 58-year-old man was diagnosed as having descending colon cancer and underwent a left colectomy with D3 node dissection and end-to-end anastomosis reconstruction. The accessory middle colic artery was secured as a feeding artery, and the middle colic artery was preserved. Diet was started on postoperative day 5 (POD5), and nausea and vomiting appeared on POD10. An upper gastrointestinal series revealed to-and-fro peristalsis in the third portion of the duodenum and dilatation of the proximal duodenum. Abdominal CT showed that the second portion of the duodenum was markedly dilated and the third portion was compressed by the superior mesenteric artery (SMA). As a result, he was diagnosed with post-operative superior mesenteric artery syndrome (SMAS) and treated with conservative therapy. The symptoms improved with a nasogastric tube, and he started to eat after POD26, followed by a successful outcome

Improved accuracy in high-frequency AC transport measurements in pulsed high magnetic fields

We show theoretically and experimentally that accurate transport measurements are possible even within the short time provided by pulsed magnetic fields. For this purpose, a new method has been devised, which removes the noise component of a specific frequency from the signal by taking a linear combination of the results of numerical phase detection using multiple integer periods. We also established a method to unambiguously determine the phase rotation angle in AC transport measurements using a frequency range of tens of kilohertz. We revealed that the dominant noise in low-frequency transport measurements in pulsed magnetic fields is the electromagnetic induction caused by mechanical vibrations of wire loops in inhomogeneous magnetic fields. These results strongly suggest that accurate transport measurements in short-pulsed magnets are possible when mechanical vibrations are well suppressed