No abstract

Terahertz (THz) communication is a key candidate for the upcoming age of beyond-fifth-generation mobile networks (B5G) or sixth-generation mobile networks (6G) in the next decade and can achieve ultra-high data rates of dozens of gigabits or even terabits per second. As the carrier frequency increases from radio frequency (RF) to the THz band, the impact of meteorological factors on the wireless link is expected to become more pronounced. In this work, we first provide an overview of the attenuation caused by atmospheric gases, fog, and rain on terrestrial THz wireless communications using the recommendations of the International Telecommunication Union-Radiocommunication (ITU-R). Measured data from the literature are used to predict the attenuation caused by snow. Because unfavorable weather conditions may harm sensitive measurement equipment, ray-tracing (RT) simulations are sometimes used as an alternative to extend sparse empirical data. In this study, the terrestrial channel in an urban scenario at 300 GHz, with a bandwidth of 8 GHz, is characterized using RT simulations under different meteorological factors. The key performance parameters are explored, including path loss (PL), Rician K-factor (KF), root-mean-square (RMS) delay spread (DS), and four angular spreads. The channel characteristics under different meteorological conditions studied in this work are expected to aid the design of future outdoor terrestrial THz communications.

A compact multimode broadband ±45° dual‐polarized base station antenna for LTE and 5G applications is proposed. By introducing folded circular ring dipoles loaded with short wires into the stepped square ring dipoles to create a new resonance mode at high frequency to achieve the purpose of extending the bandwidth. Simulation and experiment show that the antenna can achieve a bandwidth of 55.9% (2.28‐4.05 GHz) within the operating frequency (|S11| < −15 dB and |S21| < −25 dB), and the proposed antenna has a measured gain about 8.3 ± 0.9 dBi and a cross polarization ratio greater than 25 dB.

In this article, a broadband dual-polarized microstrip antenna with low profile and compact horizontal size is presented. By using the grid-slotted patch, dual modes can be excited to broaden the operating bandwidth of the proposed antenna. A broad bandwidth of 25%(1.4-1.8 GHz) for return loss >10 dB is achieved in our design. Two orthogonal linear polarization waves are excited when two pairs of aperture are utilized to couple the grid-slotted patch. Current distribution varies with frequency which results in a broad and varying beam width. Consequently, a roughly flat gain curve appears in our design. The proposed antenna achieves a low profile of 0.09 λ 0 (λ 0 is the free-space wavelength at 1.6 GHz) and a compact horizontal size. A prototype is fabricated and measured to prove the simulation.

Logic Technology and Development Center SMIC 201312For 20/16nm HK-last and MG-last process, Dummy poly is removed by Wet process. This paper studies the factors impacting the dummy poly removal process, and presents some models to explain the impacting factors. Implant process is one of main factors influencing dummy poly removal capability because the differences of implant ions and doping amount into dummy poly induce difference of poly removal rate by wet process. We also study poly surface single clean, multiple clean and thermal process. Based on the model, we plan N-type doping poly and P-type doping poly with different ion doping amounts on blank wafer and 20nm structure wafers to evaluate dummy poly removal. We find dummy poly removal rate is different between N-type doping poly and P-type doping poly, and receive different dummy poly removal trend by ion amount on N-type doping poly and P-type doping poly. The model can help to improve dummy poly removal process control.