Showing papers on "Process variable published in 2004"

Novel sizing algorithm for yield improvement under process variation in nanometer technology

Abstract: Due to process parameter variations, a large variability in circuit delay occurs in scaled technologies affecting the yield. In this paper, we propose a sizing algorithm to ensure the speed of a circuit under process variation with a certain degree of confidence while maintaining the area and power budget within a limit. This algorithm estimates the variation in circuit delay using statistical timing analysis considering both inter- and intra-die process variation and resizes the circuit to achieve a desired yield. Experimental results on several benchmark circuits show that one can achieve up to 19% savings in area (power) using our algorithm compared to the worst-case design.

Optimal process conditions of shrinkage and warpage of thin-wall parts

Abstract: Optimal process conditions of thin-wall injection molding of a cellular phone cover were investigated with the consideration of interaction effects between process parameters. L27 experimental tests based on Taguchi's method were performed, and then Cyclone Scanner, PolyCAD and PolyWorks were used to measure the shrinkage and warpage of the thin-wall injected parts to determine the optimal process conditions. Based on the results of the analysis of variables and the F-test, interaction effects for each observed factor were determined. The results indicated that the packing pressure was the most important process parameter affecting the shrinkage and warpage of the thin-wall part. The optimal process conditions were different for the shrinkage and the warpage. This was because during the injection process, the mechanisms affecting shrinkage or warpage were different. Compared with the results obtained with simplified thin-wall parts in the literature, it was found that the geometry of a real commercial part did affect the optimal process conditions and the order of influence of process parameters. The optimal process conditions determined by Taguchi's method for reducing the shrinkage and warpage were verified experimentally in this work. Polym. Eng. Sci. 44:917–928, 2004. © 2004 Society of Plastics Engineers.

An evolutionary approach for cooling system optimization in plastic injection moulding

Abstract: The cooling process is of great importance in plastic injection moulding as it has a direct impact on both productivity and product quality. Cooling process optimization is a sophisticated task which includes not only the design of cooling channels but also the selection of process parameters. Most existing optimization systems focus on either cooling channel design or process parameter selection but not both. This paper explores an approach to optimize both cooling channel design and process condition selection simultaneously through an evolutionary algorithm. The prototype system proposed in this paper is an integration of the genetic algorithm and CAE (Computer-Aided Engineering) technology. The aim is to launch a computerized system that can guide the optimization of the cooling process in plastic injection moulding. The objective is to achieve the most uniform cavity surface temperature to assure product quality.

Should observations be grouped for effective process monitoring

Abstract: During process monitoring, it is assumed that a special cause will result in a sustained shift in a process parameter that will continue until the shift is detected and the cause is removed In some cases special, however, causes may produce a transient

The significance of deposition point standoff variations in multiple-layer coaxial laser cladding (coaxial cladding standoff effects)

Abstract: Direct laser deposition (DLD) is an additive manufacturing process that builds up a part layer-by-layer by fusing metal powder to a solid substrate. A coaxial laser and powder delivery head is commonly used, and here a critical process variable is the standoff distance between the nozzle and the material deposition point. This contribution investigates the role of this variable and the effect that it has on the final part geometry. The experimental results show that good layer consistency can, in fact, be obtained with no movement of the substrate between layers for more than 20 layers, or 10 mm under tested conditions, and that poorer results are obtained by regular movement of the substrate by a badly chosen constant amount. A theoretical analysis of the situation establishes a method to estimate melt pool size using an analytically calculated temperature near the heat source. Based on this, simple heat and mass flow models are established to allow some of the results to be explained.

Design layout preparing method

Abstract: There is disclosed a method of producing a design layout by optimizing at least one of design rule, process proximity correction parameter and process parameter, including calculating a processed pattern shape based on a design layout and a process parameter, extracting a dangerous spot having an evaluation value with respect to the processed pattern shape, which does not satisfy a predetermined tolerance, generating a repair guideline of the design layout based on a pattern included in the dangerous spot, and repairing that portion of the design layout which corresponds to the dangerous spot based on the repair guideline.

Methods and apparatus for sequentially alternating among plasma processes in order to optimize a substrate

Abstract: In a plasma processing system, a method for optimizing etching of a substrate is disclosed. The method includes selecting a first plasma process recipe including a first process variable, wherein changing the first process variable by a first amount optimizes a first substrate etch characteristic and aggravates a second substrate etch characteristic. The method also includes selecting second plasma process recipe including a second process variable, wherein changing the second process variable by a second amount aggravates the first substrate etch characteristic and optimizes the second substrate etch characteristic. The method further includes positioning a substrate on a chuck in a plasma processing chamber; and striking a plasma within the plasma processing chamber. The method also includes alternating between the first plasma recipe and the second plasma recipe, wherein upon completion of the alternating, the first substrate etch characteristic and the second substrate etch characteristic are substantially optimized.

Method of patterning process metrology based on the intrinsic focus offset

Abstract: A method of controlling imaging and process parameters in a lithographic process comprises providing a control pattern having an isolated feature with a pitch greater than twice a width of an individual feature, and exposing and developing a calibration resist layer with the control pattern design at a plurality of dose and focus settings. Width of the printed calibration control pattern feature is measured near the top and bottom of the resist layer thickness, and optimum dose and focus settings are then determined. Control patterns are printed at fixed exposure dose and focus settings on a production substrate, and width is measured near the top and bottom of the resist layer thickness. The widths of the production control pattern features are compared with the control pattern model parameters, and the imaging and process parameter settings in the production process are adjusted based on the comparison of the widths.

Multi-variable operations

Abstract: Operation of a multi-variable process involves multidimensional representation of the values (pl-p12) of the process variables (Pl-P12) according to individual coordinate axes, and an operational envelope (UB,LB) derived from a group of sets of values for the process and quality variables (P1-P12,Q1-Q2) accumulated from multiple, earlier operations of the process, defines an operating zone for the process and quality variables of the process. If the current value (p7) of any process variable (P7) goes outside the envelope, an envelope (UO,LB) for a different, wider grouping of the stored data-sets is displayed at least for the quality variables (Ql-Q2). A series of nested envelopes to provide stepwise enlargement of the operating zone may be provided, but non-nested envelopes can be used where there is clustering of acceptable values of process variables of the stored data-sets. The changes to control variables to bring the values of dependent variables within a best operating range can be determined.

Bioprocess control from a multivariate process trajectory

Abstract: A multivariate bioprocess control approach, capable of tracking a pre-set process trajectory correlated to the biomass or product concentration in the bioprocess is described. The trajectory was either a latent variable derived from multivariate statistical process monitoring (MSPC) based on partial least squares (PLS) modeling, or the absolute value of the process variable. In the control algorithm the substrate feed pump rate was calculated from on-line analyzer data. The only parameters needed were the substrate feed concentration and the substrate yield of the growth-limiting substrate. On-line near-infrared spectroscopy data were used to demonstrate the performance of the control algorithm on an Escherichia coli fed-batch cultivation for tryptophan production. The controller showed good ability to track a defined biomass trajectory during varying process dynamics. The robustness of the control was high, despite significant external disturbances on the cultivation and control parameters.

Interfaces from external systems to time dependent process parameters in integrated process and product engineering

Abstract: A method and apparatus for computer modeling the production process is disclosed. An integrated product and process engineering system may be a computer modeling system that models both a generic production process and a specific individual production process. The integrated product and process engineering system may store a time dependent process parameter related to the production process, having uploaded them via an interface. The time dependent process parameters may be retrieve and displayed to the user on a display using a remote function call enabled function module. The time dependent process parameters may be uploaded from an external system or revised using a remote function call enabled function module.

Method of controlling trimming of a gate electrode structure

Abstract: A method and processing tool are provided for controlling trimming of a gate electrode structure containing a gate electrode layer with a first dimension by determining the first dimension of the gate electrode structure, choosing a target trimmed dimension, feeding forward the first dimension and the target trimmed dimension to a process model to create a set of process parameters, performing a trimming process on the gate electrode structure, including controlling the set of process parameter, trimming the gate electrode structure, and measuring a trimmed dimension of the gate electrode structure. The trimming process may be repeated at least once until the target trimmed dimension is obtained, where the trimmed dimension may be fed backward to the process model to create a new set of process parameters.

Effect of pulse frequency in gas tungsten arc welding of powder metallurgical preforms

Abstract: Pulsing of the welding current is one approach for refining the fusion zone microstructure in materials joined by fusion welding. The effect of current pulse frequency on weld bead microstructure, tensile strength, and hardness in joining of powder metallurgical steel preform sheets to wrought copper was studied. Considering weld strength as the quality characteristic in the selection of process parameters, the Taguchi method is used to analyse the effect of each process parameter individually and of their interaction on weld strength, and subsequently to determine the process parameters leading to optimum weld strength. The application of pulsed current causes iron dendrites to become more equiaxed and uniformly distributed owing to dendrite fragmentation. Further, there was an optimum frequency range over which the microstructural refinement was maximal. The same optimum frequency range corresponded to maximum tensile strength. Enhanced fluid flow and reduced thermal gradients are thought to be ...

Pattern verification method, pattern verification system, mask manufacturing method and semiconductor device manufacturing method

Abstract: A pattern verification method comprising preparing a desired pattern and a mask pattern forming the desired pattern on a substrate, defining at least one evaluation point on an edge of the desired pattern, defining at least one process parameter to compute the transferred/formed pattern, defining a reference value and a variable range for each of the process parameters, computing a positional displacement for each first points corresponding to the evaluation point, first points computed using correction mask pattern and a plurality of combinations of parameter values obtained by varying the process parameters within the variable range or within the respective variable ranges, the positional displacement being displacement between first point and the evaluation point, computing a statistics of the positional displacements for each of the evaluation points, and outputting information modifying the mask pattern according to the statistics.

Process Modelling of Equal Channel Angular Pressing for Ultrafine Grained Materials

Abstract: Equal channel angular pressing (ECAP) is a viable forming procedure to extrude material by use of specially designed channel dies without a substantial change in geometry and to make an ultrafine grained material by imposing severe plastic deformation. Because the evolution of microstructures and the mechanical properties of the deformed material are directly related to the amount of plastic deformation, the understanding of the phenomenon associated with strain development is very important in the ECAP process. The plastic deformation behaviour during pressing is governed mainly by die geometry (channel sizes, a channel angle and corner angles), material properties (strength and hardening behaviour) and process variables (temperature, lubrication and deformation speed). There is a need for modelling techniques which may permit a wider study of the effects observed for better process control and the understanding of process related phenomena. In this study, we describe a range of our continuum modelling results of the ECAP process in order to illustrate the modelling applicability. Firstly, the finite element results of ECAP modelling for various geometric factors are described. Secondly, the inhomogeneous deformation due to the hardening property of the material is explained. Lastly, modelling the temperature field coupled with stress as a typical process variable in ECAP is presented.

An Improved Adaptive Multi-way Principal Component Analysis for Monitoring Streptomycin Fermentation Process

Abstract: Multi-way principal component analysis (MPCA) had been successfully applied to monitoring the batch and semi-batch process in most chemical industry An improved MPCA approach, step-by-step adaptive MPCA (SAMPCA), using the process variable trajectories to monitoring the batch process is presented in this paper It does not need to estimate or fill in the unknown part of the process variable trajectory deviation from the current time until the end The approach is based on a MPCA method that processes the data in a sequential and adaptive manner The adaptive rate is easily controlled through a forgetting factor that controls the weight of past data in a summation This algorithm is used to evaluate the industrial streptomycin fermentation process data and is compared with the traditional MPCA The results show that the method is more advantageous than MPCA, especially when monitoring multi-stage batch process where the latent vector structure can change at several points during the batch

Process transmitter with a plurality of operating modes

Abstract: A transmitter (300) for measuring a process variable of an industrial process (304) includes a sensor (310) adapted to measure the process variable and to generate a sensor output. A mode selector (316) is adapted to select between operational modes. At least one operational mode is related to an operational range of the sensor (310). Circuitry (312) is adapted to compensate the sensor output according to the at least one operational mode and to generate a transmitter output representative of the measured process variable.

Method and system for correcting a mask pattern design

Abstract: A pattern verification method includes preparing a desired pattern and a mask pattern forming the desired pattern on a substrate, defining at least one evaluation point on an edge of the desired pattern, defining at least one process parameter to compute the transferred/formed pattern, defining a reference value and a variable range for each of the process parameters, and computing a positional displacement for each first points corresponding to the evaluation point, first points computed using correction mask pattern and a plurality of combinations of parameter values obtained by varying the process parameters within the variable range or within the respective variable ranges. The positional displacement is a displacement between first point and the evaluation point. The method further includes computing a statistics of the positional displacements for each of the evaluation points, and outputting information modifying the mask pattern according to the statistics.

Methods and apparatuses for conditioning polishing surfaces utilized during CMP processing

Abstract: Methods and apparatus are provided for conditioning of polishing surfaces utilized during CMP processing. The method comprises contacting the polishing surface and a conditioning surface with a first force, one of the surfaces coupled to a support member that has an axis. The polishing surface and/or the conditioning surface is moved at a constant velocity. Torque exerted by the support member about the axis to effect a relative position between the conditioning surface and the polishing surface is measured and used to obtain a process variable. The process variable is compared to a setpoint value for the relative position of the conditioning surface and the polishing surface. A second force is calculated and the polishing surface and the conditioning surface then are contacted with the second force, if the process variable differs from the setpoint value by more than an allowed tolerance.

Process optimisation of transfer moulding for electronic packages using artificial neural networks and multiobjective optimisation techniques

Abstract: Transfer moulding is the most common process for the encapsulation of electronic packages in semiconductor manufacturing. Quality of the moulding is affected by a large number of mould design parameters and process parameters. Currently, the parameters setting is performed by experienced engineers in a trial and error manner and often the optimal setting can not be obtained. In the face of global competition, the current practice is inadequate. In this research, a process optimisation system for transfer moulding of electronic packages is described which involves design of experiments (DOE) techniques, artificial neural networks (ANNs), multiple regression analysis and the minimax method. The system is aimed to determine the optimal mould design parameters and process parameter settings of transfer moulding of electronic packages for multiobjective problem. Implementation of the optimisation system has demonstrated that the time for the determination of optimal mould design parameters and process parameters setting can be greatly reduced and the parameters setting recommended by the system can contribute to the good quality of moulded packages without relying on experienced engineers.

Systems and methods for monitoring or controlling the ratio of hydrogen to water vapor in heat metal treating atmospheres

Abstract: Systems and methods for monitoring a heat treating atmosphere derive from at least one sensor placed in situ in the atmosphere a process variable, which is indicative of the ratio of gaseous hydrogen H 2 (g) to water vapor H 2 O (g) in the atmosphere. The systems and methods use the process variable, e.g., to control the atmosphere, or to record or display the process variable.

Nonlinear Model-based Dissolved Oxygen Control in a Biological Wastewater Treatment Process

Abstract: The dissolved oxygen (DO) concentration has been an important process parameter in the biological wastewater treatment process (WWTP). In this paper, we propose a nonlinear control scheme to maintain the dissolved oxygen level of an activated sludge system. Without any linearization or model reduction, it can directly incorporate the nonlinear DO process model with on-line estimation of the respiration rate (R) and the oxygen transfer rate (K La). Simulation results show that it outperforms a control performance of the PID controller. Since it incorporates the process disturbance and nonlinearity in the controller design, the suggested method can efficiently deal with the operating condition changes that occur frequently in the wastewater treatment process.

Computer-implemented method and carrier medium configured to generate a set of process parameters and/or a list of potential causes of deviations for a lithography process

Abstract: A computer-implemented method and a carrier medium adapted to improve lithographic processes are provided. In some embodiments, the computer-implemented method and carrier medium may be used for identifying potential causes of lithography process failure or drift. In addition or alternatively, the computer-implemented method and carrier medium may be adapted to generate a set of process parameter values for a lithography process based upon both critical dimension and overlay effect analyses of process parameter value variations. In some cases, the set of process parameter values may be selected to collectively minimize the number critical dimension and overlay variation errors produced within an image fabricated from the lithography process.

Parallel Optimization of Forging Processes for Optimal Material Properties

Abstract: Validated, internal state variable constitutive models are developed to model the complex multi‐stage forging process and predict the final forging strength and microstructure. Optimization methodologies are then used on a high performance, parallel computer to design the forging dies and temperatures that would meet minimum and maximum strength requirements and result in maximum strength uniformity. Each node on the parallel computer solves a unique finite element simulation including parametric meshing, post‐processing and metric determination. Nine shape parameters and one process parameter (temperature) are optimized to reduce strength non‐uniformity. The final process design, based on over 360 finite element simulations, meets all material requirements and results in a near uniform strength part.

Process for detecting the charge of the strainer arrangement of a dishwasher

Abstract: The method involves determining at least one loading value from at least one first and second process parameter value associated with a level of a washing liquid or from at least one first and second washing liquid level associated with a process parameter and using the loading value as a measure of the filter loading, whereby the process parameter has a definite relationship to e.g. the revolution rate of a circulation pump.

Two-line processing device installed on work site

Abstract: PROBLEM TO BE SOLVED: To provide a method, a device and a system for connecting a process variable transmitting apparatus to a two-line processing device that communicates with a control room. SOLUTION: The device used for the process control system comprises a first pair of electrically connected parts that is so composed as to be connected to a two-line process control loop. The loop includes a two line process variable transmitter. A second pair of electrically connected parts is so composed as to be connected to an input channel, having a multiple input channels. Electrical elements are connected serially in a loop that is used for digital communication with the two line process variable transmitter. COPYRIGHT: (C)2005,JPO&NCIPI