[en] Systematic summary is briefly made of the distribution, classification, formation, regional geological setting, uranium deposit type, ore-controlling geological conditions of the Mesozoic-Cenozoic basin in Guangdong area, and on this basis it is proposed that there exist different ore-controlling conditions in different types of basin and different types of deposit can be formed in them, thus indicating the direction for exploration of the basin type uranium deposit from now on and expanding the prospect of ore-finding in the basins in Guangdong area

[en] Electrostatic chucks are one of the core components of semiconductor devices. As a key index of electrostatic chucks, the clamping force must be controlled within a reasonable range. Therefore, it is essential to accurately measure the clamping force. To reduce the negative factors influencing measurement precision and repeatability, this article presents a novel method to measure the clamping force and we elaborate both the principle and the key procedure. A micro-force probe component is introduced to monitor, adjust, and eliminate the gap between the wafer and the electrostatic chuck. The contact force between the ruby probe and the wafer is selected as an important parameter to characterize de-chucking, and we have found that the moment of de-chucking can be exactly judged. Moreover, this article derives the formula calibrating equivalent action area of backside gas pressure under real working conditions, which can effectively connect the backside gas pressure at the moment of de-chucking and the clamping force. The experiments were then performed on a self-designed measuring platform. The de-chucking mechanism is discussed in light of our analysis of the experimental data. Determination criteria for de-chucking point are summed up. It is found that the relationship between de-chucking pressure and applied voltage conforms well to quadratic equation. Meanwhile, the result reveals that actual de-chucking behavior is much more complicated than the description given in the classical empirical formula. (paper)

[en] The inner surface modification process by plasma-based low-energy ion implantation (PBLEII) with an electron cyclotron resonance (ECR) microwave plasma source located at the central axis of a cylindrical tube is modeled to optimize the low-energy ion implantation parameters for industrial applications. In this paper, a magnetized plasma diffusion fluid model has been established to describe the plasma nonuniformity caused by plasma diffusion under an axial magnetic field during the pulse-off time of low pulsed negative bias. Using this plasma density distribution as the initial condition, a sheath collisional fluid model is built up to describe the sheath evolution and ion implantation during the pulse-on time. The plasma nonuniformity at the end of the pulse-off time is more apparent along the radial direction compared with that in the axial direction due to the geometry of the linear plasma source in the center and the difference between perpendicular and parallel plasma diffusion coefficients with respect to the magnetic field. The normalized nitrogen plasma densities on the inner and outer surfaces of the tube are observed to be about 0.39 and 0.24, respectively, of which the value is 1 at the central plasma source. After a 5 μs pulse-on time, in the area less than 2 cm from the end of the tube, the nitrogen ion implantation energy decreases from 1.5 keV to 1.3 keV and the ion implantation angle increases from several degrees to more than 40°; both variations reduce the nitrogen ion implantation depth. However, the nitrogen ion implantation dose peaks of about 2×10"1"0 – 7×10"1"0 ions/cm"2 in this area are 2 – 4 times higher than that of 1.18×10"1"0 ions/cm"2 and 1.63×10"1"0 ions/cm"2 on the inner and outer surfaces of the tube. The sufficient ion implantation dose ensures an acceptable modification effect near the end of the tube under the low energy and large angle conditions for nitrogen ion implantation, because the modification effect is mainly determined by the ion implantation dose, just as the mass transfer process in PBLEII is dominated by low-energy ion implantation and thermal diffusion. Therefore, a comparatively uniform surface modification by the low-energy nitrogen ion implantation is achieved along the cylindrical tube on both the inner and outer surfaces. (paper)

[en] The nitrogen mass transfer process in plasma-based low-energy ion implantation (PBLEII) is theoretically and experimentally studied in order to explore the process mechanism of PBLEII and therefore to optimize the apparatus design and the process conditions. An electron cyclotron resonance (ECR) microwave discharge generates the nitrogen plasma with a high density of 10¹¹–10¹² ions/cm³, which diffuses downstream to the process chamber along the divergent magnetic field. The nitrogen ions in the plasma implant into the surface and transport to the matrix of an austenitic stainless steel under the low negative pulsed bias of −2 kV at a process temperature of 400 °C. A global plasma model is used to simulate the ECR microwave plasma discharge for a range of working pressures and microwave powers. The fluid models are adopted to calculate the plasma downstream diffusion, the sheath expansion and the low-energy ion implantation on the surface. A nonlinear kinetic discrete model is established to describe the nitrogen transport in the austenitic stainless steel and the results are compared with the experimental measurements. Under an average implantation current density of 0.3–0.6 mA/cm², the surface nitrogen concentration in the range from 18.5 to 29 at. % is a critical factor for the nitrogen transport in the AISI 304 austenitic stainless steel by PBLEII, which accelerates the implanted nitrogen diffusion inward up to 6–12 μm during a nitriding time of 4 h

[en] There was a west-east gas transmission pipeline nearby the Yanmenguan DC grounding electrode. In order to assess the electromagnetic interference of Yanmenguan DC grounding electrode on the pipeline, an electromagnetic simulation model was established. The pipeline to earth potential was analyzed. The effects of insulation layers and insulation joints on the pipeline to earth potential were investigated. It can provide theorical support for the pratical operation of gas pipelines. (paper)

[en] The planetary gearbox, due to its unique mechanical structures, is an important rotating machine for transmission systems. Its engineering applications are often in non-stationary operational conditions, such as helicopters, wind energy systems, etc. The unique physical structures and working conditions make the vibrations measured from planetary gearboxes exhibit a complex time-varying modulation and therefore yield complicated spectral structures. As a result, traditional signal processing methods, such as Fourier analysis, and the selection of characteristic fault frequencies for diagnosis face serious challenges. To overcome this drawback, this paper proposes a signal selection scheme for fault-emphasized diagnostics based upon two order tracking techniques. The basic procedures for the proposed scheme are as follows. (1) Computed order tracking is applied to reveal the order contents and identify the order(s) of interest. (2) Vold–Kalman filter order tracking is used to extract the order(s) of interest—these filtered order(s) constitute the so-called selected vibrations. (3) Time domain statistic indicators are applied to the selected vibrations for faulty information-emphasized diagnostics. The proposed scheme is explained and demonstrated in a signal simulation model and experimental studies and the method proves to be effective for planetary gearbox fault diagnosis. (paper)

[en] It is of importance to assess the electromagnetic influcence of HVDC converter station on buried metal facilities of AC substations, fossil-fuel plants, windfarms and pipelines. Electromagnetic interference model was established based on the experimental measurement of soil resistivity and actual physical location. It was shown that the grounding potential rise (GPR) of Yijing 220kV substation, Banjing wind farm, Nanhuashan wind farm, Jiyangshan wind farm, Liugou wind farm and Limin wind farm exceeded the standard. The effects of distance, soil resistivity and injected current on GPR were also investigated. The results can provide reference significance for design and maintance of HVDC transmission engineering. (paper)

[en] As one of the core components of IC manufacturing equipment, the electrostatic chuck (ESC) has been widely applied in semiconductor processing such as etching, PVD and CVD. The clamping force of the ESC is one of the most important technical indicators. A multi-physics simulation software COMSOL is used to analyze the factors influencing the clamping force. The curves between the clamping force and the main parameters such as DC voltage, electrode thickness, electrode radius, dielectric thickness and helium gap are obtained. Moreover, the effects of these factors on the clamping force are investigated by means of orthogonal experiments. The results show that the factors can be ranked in order of voltage, electrode radius, helium gap and dielectric thickness according to their importance, which may offer certain reference for the design of ESCs. (semiconductor devices)

[en] A two-dimensional axisymmetric inductively coupled plasma (ICP) model, and its implementation in the COMSOL multiphysical software, is described. The simulations are compared with the experimental results of argon discharge from the gaseous electronics conference RF reference cell in the inductively coupled plasma mode. The general trends of the number density and temperature of electrons with radial scanning are approximately correct. Finally, we discuss the reasons why the comparisons are not in agreement, and then propose an improvement in the assumptions of the Maxwellian electron energy distribution function and reaction rate. (semiconductor technology)

[en] In order to measure the micro force in a micro-nano device, a new measuring method for micro force is introduced. In this paper, a measuring system based on a micro-electro-mechanical systems (MEMS) planar torsional spring is presented, which contains a support block, MEMS planar torsional spring, a support arm, and a laser displacement detection system. The micro force has been obtained by measuring the moving distance of the light spot which is reflected by the MEMS planar torsional spring. The spring sample has been prepared with laser processing technology, and the stiffness is obtained by theoretical calculation, simulation, and calibration. The results show that the torsional stiffness of the MEMS planar torsional spring is 3.7181 Nm rad⁻¹. The measurement system has a measuring range of ±159 mN. The maximum error of mean in repeated measurement is 1.25% of the reference value, and the repeatability standard deviation is a maximum 4.44% of the reference value. (paper)