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Etch characteristics of ovonic threshold switch (OTS) materials composed of Ge–As–Te for a phase-change random access memory (PCRAM) has been investigated using reactive ion etching via hydrogen-based gases such as H2, CH4, NH3, CH4 + H2, and CH4 + NH3. Among the investigated hydrogen-based gases, NH3 showed the highest etching rate of about 0.52 nm s−1, but the formation of nitride compounds and the increased roughness were observed on the OTS surface by nitrogen. The use of other hydrogen-based gases such as CH4 and CH4 + H2 showed the deposition and low OTS etch rate, respectively, due to the presence of carbon in CH4. Even though H2 showed the better etch characteristics due to the no surface residues or compounds on the OTS surface related to carbon or nitrogen in the etch gases, the best OTS etch characteristics such as the second highest etch rate of 0.45 nm s−1, the lowest surface roughness of 0.21 nm, and no surface residues or compounds were observed with CH4 + NH3 due to the removal of carbon and nitrogen on the surface by the formation of volatile CN compounds while maintaining a high hydrogen atomic concentration in the plasma.

Magnetic tunneling junction (MTJ) materials such as CoFeB, Co, Pt, MgO, and the hard mask material such as W and TiN were etched with a reactive ion beam etching (RIBE) system using H2/NH3. By using gas mixtures of H2 and NH3, especially with the H2/NH3( 2:1) ratio, higher etch rates of MTJ related materials and higher etch selectivities over mask materials (>30) could be observed compared to those etching using pure H2( no etching) and NH3. In addition, no significant chemical and physical damages were observed on etched magnetic materials surfaces and, for CoPt and MTJ nanoscale patterns etched by the H2/NH3( 2:1) ion beam, highly anisotropic etch profiles >83° with no sidewall redeposition could be observed. The higher etch rates of magnetic materials such as CoFeB by the H2/NH3( 2:1) ion beam compared to those by H2 ion beam or NH3 ion beam are believed to be related to the formation of volatile metal hydrides (MH, M = Co, Fe, etc) through the reduction of M-NHx( x = 1 ∼ 3) formed in the CoFeB surface by the exposure to NH3 ion beam. It is believed that the H2/NH3 RIBE is a suitable technique in the etching of MTJ materials for the next generation nanoscale spin transfer torque magnetic random access memory (STT-MRAM) devices.

OBJECTIVE Anterior cervical discectomy and fusion (ACDF) is a choice of surgical procedure for cervical degenerative diseases associated with radiculopathy or myelopathy. However, the patients undergoing ACDF still have problems. The purpose of the present study is to evaluate the radiologic results of 3 different methods in single-level ACDF. METHODS We conducted a retrospective collection of radiological data from January 2011 to December 2014. A total of 67 patients were included in this study. The patients were divided into 3 groups by operation procedure: using stand-alone cage (group cage, n=20); polyether-ether-ketone (PEEK)-titanium combined anchored cage (group AC, n=21); and anterior cervical cage-plate (group CP, n=26). Global cervical lordosis (C2-C7 Cobb angle), fused segment height, fusion rate, and cervical range of motion (ROM) were measured and analyzed at serial preoperative, postoperative, 6-month, and final 1-year follow-up. RESULTS Successful bone fusion was achieved in all patients at the final follow-up examination; however, the loss of disc height over 3 mm at the surgical level was observed in 6 patients in group cage. Groups AC and CP yielded significantly better outcomes than group cage in fused segment height and cervical ROM(p=0.01 and p=0.02, respectively). Furthermore, group AC had similar radiologic outcomes to those of group CP. CONCLUSION The PEEK-titanium combined anchored cage may be a good alternative procedure in terms of reducing complications induced by plate after ACDF.

In patients with tumors and spinal cord lesions, inflammation and tissue infection can result in mass effect detection on imaging. As a result, surgical biopsy procedures are often performed on the lesions. We report a rare case in which the thickening ligamentum flavum (LF) appeared to be a tumor in the epidural space of the cervical spine based on imaging findings. A 52-year-old man visited our outpatient clinic with severe shoulder pain and radicular pain in his right arm that had developed gradually after a traffic accident two months earlier. Magnetic resonance imaging of the cervical spine revealed an extradural mass at the cervicothoracic junction level. Suspecting a tumor, spinal decompression surgery was performed and a biopsy of the mass was obtained. At the time of surgery, the LF was thick and compressed the spinal cord. After successful removal of the LF, the spinal cord appeared normal. Histopathological examination confirmed the mass as the LF. The patient was discharged without pain or weakness two weeks postoperatively. This case demonstrated that when the LF of the cervicothoracic junction is thickened, it may be misdiagnosed as a cervical spine tumor compressing the spinal cord.

A 57-year-old man complained of severe lower back pain and radicular pain in both legs for 1 week after falling from a ladder. Magnetic resonance imaging (MRI) of the spine showed a subdural hematoma (SDH), which was surgically removed. The patient had no back pain or the radicular leg pain at 2 weeks post-surgery. However, he complained of diffuse headaches upon follow-up. Brain computed tomography (CT) and MRI revealed an intracranial SDH, which was immediately removed by surgery. During his 1-year follow-up, he reported that the pain had resolved without recurrence. Simultaneous spinal and intracranial SDH are rare and no standard treatment exists for this condition. This case suggests that it is possible that an intracranial SDH can migrate into the cerebrospinal fluid (CSF) space through an arachnoid tear. CSF circulation allows the intracranial SDH to enter subarachnoid spaces encasing the spinal cord. In order to prevent irreversible damage, surgical intervention should be considered for case of spinal SDH with progressive neurological deficits.

The high speed NAND flash memory cell with a read access time of 80 ns has been demonstrated. In the process integration of the high speed cell, complementary polycide bit lines with the ground selection scheme, self-aligned field through implantation, and metal source line have been introduced. The reliable high speed NAND cell operation has been achieved by enhanced sensing voltage swing, increased cell current and reduced bit line loading.