Effects Of Process Parameter Variations Research Articles

Impact of process parameters variation on noise and linearity performances of GC-JL-GAA MOSFET

ABSTRACT The short channel effects are improved in GC-JL-GAA MOSFETs by raising the channel’s graded doping level. The noise and linearity of the device plays a crucial role in RFIC circuit applications. Therefore, this article presents a comprehensive analysis of noise and linearity parameters of graded channel junction-less-gate-all-around (GC-JL-GAA) MOSFET with process parameter variations through 3D Silvaco ATLAS device simulator. This paper investigates the noise parameters such as Noise Conductance (NC), minimum noise figure (NFmin), and optimum source impedance (Z0). To comprehend the performance of GC-JL-GAA MOSFETs, the noise characteristics with changes in channel thickness, channel length, high-k gate oxide, and oxide thickness are examined and compared. Moreover, the effect of process parameter variation on linearity FOMs such as gm2, gm3, IIP3, IMD3, VIP2, VIP3, and 1-db compression point are also examined. The GC-JL-GAA device, however, provides improved noise and linearity performance parameters for lower channel length of the device as per the performance evaluation. Furthermore, it has been observed that high-k gate oxide deteriorates noise and linearity performance of GC-JL-GAA MOSFETs. Based on the results of the performance evaluation, it has been revealed that the GC-JL-GAA devices are suitable to be employed in Radio Frequency (RF) applications.

Effects of wet granulation process variables on the quantitative assay model of transmission Raman spectroscopy for pharmaceutical tablets

Transmission Raman spectroscopy (TRS) is a process analytical technology tool for nondestructive analysis of drug content in tablets. Although wet granulation is the most used tablet manufacturing method, most TRS studies have focused on tablets manufactured via direct compression. The effects of upstream process parameter variations, such as granulation, on the prediction performance of TRS quantitative models are unknown. We evaluated the effects of process parameter variations during granulation on the prediction performance of the TRS quantitative model. Tablets with a drug concentration of 1%w/w were used. We developed PLS calibration models for the drug concentration range of 70–130% label claims. Subsequently, we predicted the drug content of the tablets with different granulation parameters. The results of our study demonstrate that the variation in the predicted recovery due to the variation in granulation parameters was practically acceptable. The calibration model showed a good prediction performance for tablets manufactured at different granulation scales and thicknesses. Therefore, we conclude that TRS quantitative models are robust to variations in upstream processes, such as granulation and downstream variations in tableting parameters. These results suggest that TRS is a versatile non-destructive quantitative analysis method that can be applied in tablet manufacturing.

Kinetic studies and CFD-based reaction modeling for insights into the scalability of ADC conjugation reactions.

The manufacturing of antibody-drug conjugates (ADCs) involves the addition of a cytotoxic small-molecule linker-drug (= payload) to a solution of functionalized antibodies. For the development of robust conjugation processes, initially small-scale reaction tubes are used which requires a lot of manual handling. Scale-up to larger reaction vessels is often knowledge-driven and scale-comparability is solely assessed based on final product quality which does not account for the dynamics of the reaction. In addition, information about the influence of process parameters, such as stirrer speed, temperature, or payload addition rates, is limited due to high material costs. Given these limitations, there is a need for a modeling-based approach to investigate conjugation scale-up. In this work, both experimental kinetic studies and computational fluid dynamics (CFD) conjugation simulations were performed to understand the influence of scale and mixing parameters. In the experimental part, conjugation kinetics in small-scale reaction tubes with different mixing types were investigated for two ADC systems and compared to larger bench-scale reactions. It was demonstrated that more robust kinetics can be achieved through internal stirrer mixing instead of external mixing devices, such as orbital shakers. In the simulation part, 3D-reactor models were created by coupling CFD-models for three large-scale reaction vessels with a kinetic model for a site-specific conjugation reaction. This enabled to study the kinetics in different vessels, as well as the effect of process parameter variations in silico. Overall, it was found that for this conjugation type sufficient mixing can be achieved at all scales and the studied parameters cause only deviations during the payload addition period. An additional time-scale analysis demonstrated to aid the assessment of mixing effects during ADC process scale-up when mixing times and kinetic rates are known. In summary, this work highlights the benefit of kinetic models for enhanced conjugation process understanding without the need for large-scale experiments.

Comparative Life Cycle Assessment of Hardmetal Chemical Recycling Routes

Secondary hardmetal is a large part of the supply for new hardmetal products, yet the environmental impacts of hardmetal recycling remain unknown to a large degree. The goal of this study was to evaluate the gate-to-gate impacts of tungsten and cobalt recovery by chemical recycling. The LCI data was obtained from process simulations and the environmental impact categories were calculated using GaBi software. The simulations were used to study process performance and to investigate the effect of process parameter variation on the environmental impact indicators. Compared to primary production, chemical recycling decreased impacts by more than 50% in all investigated impact categories. The global warming potential for treating 1 metric ton of hardmetal scrap by standard chemical recycling to APT and Co(OH)2 was 6121 kg CO2-eq., freshwater consumption 142 m3, eutrophication potential 2.3 kg P-eq., ozone depletion potential 0.0030 kg CFC-11-eq., acidification potential 91 kg SO2-eq., and photochemical ozone formation potential 11 kg NOx-eq. Process hotspots depended on the impact category of interest, but in most cases included oxidation of the scrap material and APT production. Major contributors to environmental impacts included electricity consumption, leaching chemicals, and heating required by the oxidation.

Surface Inductance of Superconductive Striplines

Inductance in superconductive circuits plays a significant role in rapid single flux quantum (RSFQ) systems. Inductance estimation is a challenging issue. The microwave behavior of these inductances is characterized by the surface inductance of a line. A methodology to accurately estimate the surface inductance of a stripline is the focus of this brief. A closed-form expression describing the dependence of the surface inductance of a stripline on the line thickness, magnetic field, and current density is provided. The effects of process parameter variations on the surface inductance are also discussed. An expression to model the effects of the trapezoidal geometry of a stripline is presented. The dependence of the surface inductance on the oxide and metal layer thicknesses is also presented. The objective is to provide an accurate estimate of the surface inductance for use in automated routing of VLSI complexity RSFQ circuits.

Temperature-dependent material removal during pulsed laser processing of CFRP composites

Understanding the material removal mechanism and thermal characteristics in pulsed laser machining of carbon fiber reinforced polymer (CFRP) composites is significantly important for optimizing the process parameters and strategies, which helps improve the processing quality of workpiece and inhibit the processing defects. However, the current studies mainly focused on the effect of process parameter variation on heat affected zone (HAZ) size and processing efficiency during pulsed laser processing of CFRP laminates. These studies did not well reveal the formation mechanism of machining defects related to temperature characteristics during the material removal process. Herein, this study proposes a material removal mechanism referred to thermal evaporation and oxidation of fiber and matrix, and mechanical removal associated with the temperature characteristics in pulsed laser machining of CFRP composites. Comparative laser ablation experiments of CFRP were conducted in air and in vacuum to verify the material removal mechanism. Besides, temperature characteristics and dynamic images during CFRP removal process were obtained via utilizing an infrared pyrometer and a high-speed camera, respectively. The results show that, in the absence of atmospheric pressure, the work done by recoil pressure improves the mechanical removal efficiency, and the jetting speed of removed carbon fiber reaches up to 45 m/s. The existence of airflow results in improving instantaneous temperature, but reducing average temperature in laser processing region.

Probabilistic process simulation to predict process induced distortions of a composite frame

Within this work, an enhanced simulation strategy for predicting process-induced distortions and residual stresses of composite structures is developed, while taking into account probabilistic variations. The simulation strategy is demonstrated for a carbon fibre-reinforced frame of an aircraft fuselage. Based on a sequentially coupled temperature-displacement analysis, temperature and degree of cure distributions as well as stresses, strains, and distortions are determined. For the description of the reaction kinetic, a phenomenological-based model considering chemical and diffusion-controlled reactions is introduced. The mechanical material behavior is described by a viscoelastic material model depending on temperature, time, and degree of cure. Corresponding process-induced distortions and occurring residual stresses are calculated and analyzed. The results of the process-induced distortions are used to derive a compensated tooling design. To analyze the effect of statistical and systematic deviations of underlying process and material parameters, a procedure for a probabilistic process simulation is created. Based on a first sensitivity analysis, a design of experiment is performed over a specified parameter range. From this surrogate, models are derived to enable a full but efficient probabilistic analysis of spring-in angles and residual stresses at multiple frame positions. The effect of process parameter variations and fluctuation of inherent material properties on process-induced distortions is assessed. Moreover, the influence of different process cycles is shown. This allows to determine the expected range of the final part distortion and to derive the resulting tolerances during assembly. For validation of the probabilistic process simulation, several frames are manufactured at different process conditions, and frame geometries are measured by digital image correlation technique. The resulting part thicknesses, spring-in angles, and global frame distortions are determined. Finally, a comparison of measurements and probabilistic predictions is given, and results are evaluated with respect to main sensitivities.

Analysis and improved process response prediction of laser- assisted automated tape placement with PA-6/carbon tapes using Design of Experiments and numerical simulations

Laser-assisted thermoplastic automated tape placement (LATP) enables the additive manufacturing of composites. The quality of parts depends on the temperature distribution during processing and on the thermal history of the laminate. We demonstrate that process response variables e.g., maximum process temperature and the thermal history can be predicted by surrogate models. These models are analytical models, which are created by a Design of Experiments approach. They are evaluated in real time and allow for the fast prediction of process responses as a function of different process parameters. The models are based on data, which are obtained by computer experiments with a 2D simulation model of the LATP process. The surrogate models were applied to analyze the effects of process parameter variations. The laser power and placement velocity were found to be most influential. The capability to make these process predictions in real-time presumably improves manufacturing of complex shaped parts.

Effect of Process Parameter Variation on Purity during Rotary Fractional Crystallization of Aluminum

High pure and ultrapure Aluminum is increasingly used in highly corrosion resistant applications or to replace copper in conductive parts such as high voltage cable and transformers due to their higher electrical conductivity properties. Ultrapure Aluminum is also used in semiconductors industry. Hence, the market demands innovative refining technologies, which consume less energy, take less time and lead to higher resource efficiencies. The most common methodology to produce ultrapure Aluminum is zone refining, based on the principle of fractional crystallization. Zone refining is however a very time-consuming process. In order to achieve a purity of 6N, several passes along the crucible with each full day treatment must be carried out. Also this method cannot be conducted continuously. This paper presents first time a new and eco-efficient method, which offers high potential to meet the mentioned multi-dimensional demands. Firstly, distribution coefficients of main impurities in Aluminum—a deciding factor to forecast and assess the removal behavior of impurities-were studied theoretically as a function of temperature using thermo-chemical calculation in FactSageTM. Secondly, the innovative method using a rotating and gas cooled crystallizer (“cooled finger”) was developed to validate the principle. The influencing process parameters such as temperature gradient, cooling gas flow rate, etc. were experimentally investigated and the theoretical results could be verified.

Effect of Process Parameter Variation on the Dimensions of Press-Formed Paperboard Trays

The dimensional accuracy of packages has a great effect on operation of the production and supply chain. In this research, the dimensional accuracy of trays made of polymer-coated paperboard and the effect of all essential press forming process parameters on outer dimensions of the trays were studied to obtain data for the press forming and lid sealing process optimization and for the forming tool design. Paperboard trays were analysed and measured with a quality monitoring system that includes a smart camera and a backlit table. Trays with varying dimensions were sealed to investigate the effect of the package size and the product weight to the residual oxygen in the package’s headspace gas. Results showed that all heat related parameters, i.e., mould temperatures, dwell time, and pressing speed can be used to adjust the outer dimensions of the paperboard tray. Lid sealing process was found to reduce size of the trays and even out size differences substantially. All produced trays were measured to be bigger both in length and in width compared to the design values of the mould set. Therefore the mould set has to be designed undersized to obtain trays with certain outer dimensions.

Analysis of double-gate FinFET-based address decoder for radiation-induced single-event-transients

In this study, the authors evaluate different schemes of address decoders based on bulk, single gate (SG) silicon-on-insulator (SOI) and double gate (DG) FinFET technology. Schemes differ in terms of back gate connections, and swing on the enable and address lines. The analysis for delay, power dissipation and critical charge has been carried out. Radiation induced single event transients and multiple bit upsets in address decoder have been studied. For radiation hardened applications, tied gate configuration has been found to be good choice over bulk, SG-SOI and independent gate configurations. The effect of process parameter variations on different schemes has been studied. HSPICE simulations have been performed with 45 nm bulk, SG-SOI and DG-FinFET predictive technology models.

Sequential Lateral Solidification Processing for Polycrystalline Si TFTs

The sequential lateral solidification (SLS) process is an excimer-laser projection-based scheme for crystallization of thin films on amorphous substrates. This method can be used to readily produce a wide range of microstructures through manipulation of grain boundary placement within the crystallized material. In this paper, we focus on the 2-shot SLS process for crystallization of thin Si films for thin-film transistor (TFT) applications. We have investigated the effect of process parameter variation on the resulting microstructure, as well as on the performance of TFTs fabricated on the material. The 2-shot SLS microstructure was further engineered to reduce anisotropy of the TFT performance relative to the lateral growth direction using additional laser scans. Through this method, we were able to improve the mobility directionality ratio between devices with majority carrier flow parallel and perpendicular to the lateral growth direction, respectively, from 0.3 to over 0.7. Post-SLS process thinning and planarization of the Si surface was used to improve the uniformity and performance of the TFT devices.

Simulation of critical dimension error using Monte Carlo method and its experimental verification

In order to assess the effects of process parameter variations, we developed an optical lithography simulation program that handles the parameter variations statistically by the Monte Carlo (MC) method and predicts the mean and standard deviation of critical dimensions (CDs). As an application of the simulation program, we analyzed the error sources that contribute to the in-shot wafer CD uniformity. For experiments, we employed an attenuated phase-shift mask that is actually used for manufacturing a memory device. The CD uniformity of the mask was 4 nm on wafer scale. We performed a MC simulation using mask uniformity of 4 nm, illumination uniformity of 3%±1% (where the error stands for three times the standard deviation), defocus of 0.0±0.2 μm, mask transmittance error of ±0.3%, and mask phase error of ±5°. Simulation gave wafer CD uniformities of 19.2 and 13.3 nm for 0.7 and 0.8 NA, respectively. These predictions agree reasonably well with experimental values 21.7 and 11.4 nm. The error sources were analyzed for both values of NA. In either case, the contribution of mask uniformity is very significant, being about 85%.

Effects of process parameter variations on the removal rate in chemical mechanical polishing of 4H-SiC

The effects of temperature, slurry pH, applied pressure, and polishing rotation rate on the material removal rate during chemical mechanical polishing (CMP) of 4H-silicon carbide wafers using colloidal silica slurry and polyurethane/polyester fiber polishing pads have been studied. Measured removal rates varied from around 100 A/hr to nearly 2500 A/hr depending on the values of the various parameters. The amount of material removed was determined by measuring the wafer mass before and after polishing. Variations in temperature and slurry pH did not produce significant changes in the measured removal rates. Higher polishing pressures resulted in increased material removal rates from 200 to 500 A/hr but also produced excessive polishing pad damage. Variations in pad rotational speeds produced the largest changes in material removal rates, from around 200 to around 2000 A/hr for rotational speeds between 60 and 180 rpm, but the variations were non-linear and somewhat inconsistent. This CMP formula is shown to consistently produce damage free surfaces but the optimum removal rate is slow.

Corrosion Behavior of Carbon Steel in the CO2 Absorption Process Using Aqueous Amine Solutions

The present study provides comprehensive information on the effects of process parameter variations on the corrosion behavior of carbon steel in CO2 absorption systems using aqueous amine solutions. The process parameters of interest are amine type, concentration of the amine solutions, solution temperature, CO2 loading, and oxygen content. An electrochemical testing technique was used for determining the system corrosiveness in terms of polarization behavior and corrosion rate. The experimental results suggest that the corrosion behavior is considerably sensitive to the variations in the process parameters. Increases in amine concentration, solution temperature, CO2 loading, and oxygen content accelerate the corrosion rate in the systems. In addition, different amine types yield different degrees of the system corrosiveness. Comparisons of the corrosiveness among single amine systems as well as between mixed amine systems and their precursors are also presented.

Buffered Clock Tree Synthesis with Non-Zero Clock Skew Schedulingfor Increased Tolerance to Process Parameter Variations

An integrated top-down design system is presented in this paper for synthesizing clock distribution networks for application to synchronous digital systems. The timing behavior of a synchronous digital circuit is obtained from the register transfer level description of the circuit, and used to determine a non-zero clock skew schedule which reduces the clock period as compared to zero skew-based approaches. Concurrently, the permissible range of clock skew for each local data path is calculated to determine the maximum allowed variation of the scheduled clock skew such that no synchronization failures occur. The choice of clock skew values considers several design objectives, such as minimizing the effects of process parameter variations, imposing a zero clock skew constraint among the input and output registers, and constraining the permissible range of each local data path to a minimum value. The clock skew schedule and the worst case variation of the primary process parameters are used to determine the hierarchical topology of the clock distribution network, defining the number of levels and branches of the clock tree and the delay associated with each branch. The delay of each branch of the clock tree is physically implemented with distributed buffers targeted in CMOS technology using a circuit model that integrates short-channel devices with the signal waveform shape and the characteristics of the clock tree interconnect. A bottom-up approach for calculating the worst case variation of the clock skew due to process parameter variations is integrated with the top-down synthesis system. Thus, the local clock skews and a clock distribution network are obtained which are more tolerant to process parameter variations. This methodology and related algorithms have been demonstrated on several MCNC/ISCAS-89 benchmark circuits. Increases in system-wide clock frequency of up to 43% as compared with zero clock skew implementations are shown. Furthermore, examples of clock distribution networks that exploit intentional localized clock skew are presented which are tolerant to process parameter variations with worst case clock skew variations of up to 30%.

Advanced Fault Detection and Isolation Schemes Using Nonlinear and Robust Observers

This paper deals with the problem of robust fault detection and isolation (FDI) in dynamic systems using analytical redundancy. In order to reduce the effect of process parameter variations, two novel observer schemes for FDI are described. The first makes use of nonlinear observers in order to avoid parameter variations that would be caused by a linearization of the nonlinear process model in the observer scheme. The second considers robust observers that are totally invariant to unknown inputs or parameter variations. The achievements of the resulting FDI schemes are demonstrated by two examples of application, a level control system in a three tank system and a position control system of an inverted pendulum.

Application of Observers to Instrument Failure Detection

This paper discusses the application of Luenberger observers to instrument failure detection (IFD). Several methods to generate functional redundancy developed in recent years are reviewed. The effect of process parameter variations is considered. With the aid of sensitivity analysis a motivation for Clark's simplified IFD scheme is given. Clark's dedicated observer scheme (DOS) is modified by application of robust observer design (R0S). The results of a simulation study of instrument failure detection by ROS in a nuclear power plant are presented.

補償のあるオンオフ制御系におけるリミットサイクル

This paper deals with self oscillations in on-off control systems including a process with dead time. Unique properties of the systems with feedback compensation are pointed out, and analyzed by Tsypkin's method.First, self oscillation of uncompensated on-off control systems including a higher order process are analyzed in detail, and effect of process parameter variation on the oscillation period and amplitude are investigated.Then, oscillation modes of control systems without compensation or with series compensation are investigated and it is shown that these systems can't have more than one oscillation mode.In the case of systems with feedback compensation, self oscillation can have many modes and there exist jumping phenomena among these oscillation modes. Effect of disturbance and gradual change of system parameters on these phenomena are clarified.Finally, stability of limit cycles in above systems are described.