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Semiconductor Manufacturing, IEEE Transactions on

Issue 1 • Date Feb 2000

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Displaying Results 1 - 11 of 11
  • Mechanisms for synergistic oxidation of organics in ultrapure water systems

    Publication Year: 2000 , Page(s): 1 - 9
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    A mechanistic model is developed for the distribution, oxidation, and removal of organic impurities in typical polishing loops of ultrapure water (UPW) plants. The model is applied to the case of the oxidation of organics by ultraviolet (UV), ozone, and a unique method of adding ozone to the UV unit. The model is validated with direct experimental measurements using various oxidation tests. In particular, the accumulation problem related to the recalcitrant (hard to remove) impurities in the UPW systems with recycle is explained. The model is also used to analyze the dynamic behavior of polishing and reclaim/recycle loops. The results show the potential oscillatory behavior of UPW loops in case of impurity surges. This behavior is important and needs to be prevented to avoid metrology and control problems View full abstract»

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  • Adaptive optimization of run-to-run controllers: the EWMA example

    Publication Year: 2000 , Page(s): 97 - 107
    Cited by:  Papers (43)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    This paper presents a recursive scheme for optimizing the gain of an exponentially weighted moving average (EWMA) controller under stability constraints. The objective is to minimize the asymptotic mean square error in the output with minimal a priori information. The algorithm hinges on a simple representation of the optimal EWMA gain. Both step and drift disturbances are considered. It is shown that the gain sequence generated by the algorithm always yields a stable system. Furthermore, this sequence is shown to converge to a suboptimal value. Extensions to the algorithm to the case where there is model uncertainty are also presented. The algorithm is verified via simulation. Data from a manufacturing implementation are presented View full abstract»

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  • Estimation of contamination levels in a chemical recirculation system for semiconductor wafer processing

    Publication Year: 2000 , Page(s): 10 - 15
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    A theoretical analysis is presented of the contamination buildup in a generic chemical recirculation system used in semiconductor wafer processing. Mathematical expressions are derived for useful quantities, such as the maximum possible concentration of contaminant in the recirculation tank and the number of processes required to reach any particular concentration level. Recirculation systems are analyzed wherein the amount of chemical used and the amount of contaminant picked up per process cycle are either constant or process dependent. Sample calculations are presented for the two cases. The mathematical equations derived in the study are presented in a form that can be easily extended to the analysis of more complex recirculation systems and the optimization of chemical supplies and processes for maximum performance View full abstract»

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  • Modeling of interconnect capacitance, delay, and crosstalk in VLSI

    Publication Year: 2000 , Page(s): 108 - 111
    Cited by:  Papers (25)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    Increasing complexity in VLSI circuits makes metal interconnection a significant factor affecting circuit performance. In this paper, we first develop new closed-form capacitance formulas for two major structures in VLSI, namely: (1) parallel lines on a plane and (2) wires between two planes, by considering the electrical flux to adjacent wires and to ground separately. We then further derive closed-form solutions for the delay and crosstalk noise. The capacitance models agree well with numerical solutions of three-dimensional (3-D) Poisson equation as well as measurement data. The delay and crosstalk models agree well with SPICE simulations View full abstract»

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  • Economical clean dry air system for closed manufacturing system

    Publication Year: 2000 , Page(s): 16 - 23
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    We demonstrated that the organic carbon contaminants influenced the J-E characteristics of a gate oxide. Molecular-contamination-free clean dry air (CDA) is a choice for the atmosphere control in a closed manufacturing system. The adsorption and desorption characteristics, which are important items for the design and operation of CDA production plants, were confirmed with both a dynamic simulation and a pilot column. Based on the results, we built a CDA plant with a capacity of 4000 m3/h, and confirmed that each contamination concentration was less than 10 ppb. We also proposed the economical CDA system using a power recycle device which has been newly developed. Using this CDA system, it is possible to reduce the power consumption in the CDA plant. Also, it is possible to realize the circulation of the used CDA without generating more contamination or power consumption View full abstract»

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  • An efficient photoresist development simulator based on cellular automata with experimental verification

    Publication Year: 2000 , Page(s): 61 - 75
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1028 KB)  

    An efficient and practical photoresist development simulator based on cellular automata is presented. Image reversal and chemical amplification processes are also simulated using this simulator. To verify the simulator, a series of experiments have been designed and performed using the Shipley SNR-248 negative resist, a stepper, and a deep ultraviolet source at 248 nm. Experiments were performed for periodic and isolated lines with pitches 300, 400, 500, and 1000 nm, for exposure energy doses of 11, 13, 17, and 23 mJ/cm2, and with developer temperatures of 0, 20, and 80°C. In all cases, the simulator results were found to be in very good agreement with the corresponding experimental results. The simulator has also successfully reproduced the incomplete opening effect observed in the case of close-spaced parallel lines View full abstract»

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  • Level-specific lithography optimization for 1-Gb DRAM

    Publication Year: 2000 , Page(s): 76 - 87
    Cited by:  Papers (70)  |  Patents (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    A general level-specific lithography optimization methodology is applied to the critical levels of a 1-Gb DRAM design at 175- and 150-nm ground rules. This three-step methodology-ruling out inapplicable approaches by physical principles, selecting promising techniques by simulation, and determining actual process window by experimentation-is based on process latitude quantification using the total window metric. The optimal lithography strategy is pattern specific, depending on the illumination configuration, pattern shape and size, mask technology, mask tone, and photoresist characteristics. These large numbers of lithography possibilities are efficiently evaluated by an accurate photoresist development bias model. Resolution enhancement techniques such as phase-shifting masks, annular illumination and optical proximity correction are essential in enlarging the inadequate process latitude of conventional lithography View full abstract»

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  • Measurement of wave-front aberrations in high-resolution optical lithographic systems from printed photoresist patterns

    Publication Year: 2000 , Page(s): 24 - 33
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    A new method of measurement of wave-front aberrations in high-resolution optical lithographic systems used for semiconductor manufacturing is proposed. The method is based on the measurement of the positional shifts and focus offsets of a set of printed photoresist grating patterns with different periods and orientations, produced under nearly fully coherent illumination condition. The proposed experimental procedures are described in detail and various sources of systematic and random errors are discussed. It is estimated that a measurement precision of λ/50 for the wave-front aberrations at selected points on the lens pupil can be achieved with this method View full abstract»

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  • Optimal predictive control with constraints for the processing of semiconductor wafers on bake plates

    Publication Year: 2000 , Page(s): 88 - 96
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    An optimal control scheme is designed to improve repeatability by minimizing the loading effects induced by the common processing condition of placement of a semiconductor wafer at ambient temperature on a large thermal-mass bake plate at processing temperature. The optimal control strategy is a model-based method using linear programming to minimize the worst-case deviation from a nominal temperature set point during the load disturbance condition. This results in a predictive controller that performs a predetermined heating sequence prior to the arrival of the wafer as part of the resulting feedforward/feedback strategy to eliminate the load disturbance. This procedure is based on an empirical model generated from data obtained during closed-loop operation. It is easy to design and implement for conventional thermal processing equipment. Experimental results are performed for a commercial conventional bake plate and depict an order-of-magnitude improvement in the settling time and the integral-square temperature error between the optimal predictive controller and a feedback controller for a typical load disturbance View full abstract»

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  • Using neural networks to construct models of the molecular beam epitaxy process

    Publication Year: 2000 , Page(s): 34 - 45
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    This paper presents the systematic characterization of the molecular beam epitaxy (MBE) process to quantitatively model the effects of process conditions on film qualities. A five-layer, undoped AlGaAs and InGaAs single quantum well structure grown on a GaAs substrate is designed and fabricated. Six input factors (time and temperature for oxide removal, substrate temperatures for AlGaAs and InGaAs layer growth, beam equivalent pressure of the As source and quantum well interrupt time) are examined by means of a fractional factorial experiment. Defect density, X-ray diffraction, and photoluminescence are characterized by a static response model developed by training back-propagation neural networks. In addition, two novel approaches for characterized reflection high-energy electron diffraction (RHEED) signals used in the real-time monitoring of MBE are developed. In the first technique, principal component analysis is used to reduce the dimensionality of the RHEED data set, and the reduced RHEED data set is used to train neural nets to model the process responses. A second technique uses neural nets to model RHEED intensity signals as time series, and matches specific RHEED patterns to ambient process conditions. In each case, the neural process models exhibit good agreement with experimental results View full abstract»

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  • Neurofuzzy modeling of chemical vapor deposition processes

    Publication Year: 2000 , Page(s): 46 - 60
    Cited by:  Papers (9)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    The modeling of semiconductor manufacturing processes has been the subject of intensive research efforts for years. Physical-based (first-principle) models have been shown to be difficult to develop for processes such as plasma etching and plasma deposition, which exhibit highly nonlinear and complex multidimensional relationships between input and output process variables. As a result, many researchers have turned to empirical techniques to model many semiconductor processes. This paper presents a neurofuzzy approach as a general tool for modeling chemical vapor deposition (CVD) processes. A five-layer feedforward neural network is proposed to model the input-output relationships of a plasma-enhanced CVD deposition of a SiN film. The proposed five-layer network is constructed from a set of input-output training data using unsupervised and supervised neural learning techniques. Product space data clustering is used to perform the partitioning of the input and output spaces. Fuzzy logic rules that describe the input-output relationships are then determined using competitive learning algorithms. Finally, the fuzzy membership functions of the input and output variables are optimally adjusted using the backpropagation learning algorithm. A salient feature of the proposed neurofuzzy network is that after the training process, the internal units are transparent to the user, and the input-output relationship of the CVD process can be described linguistically in terms of IF-THEN fuzzy rules. Computer simulations are conducted to verify the validity and the performance of the proposed neurofuzzy network for modeling CVD processes View full abstract»

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Aims & Scope

The IEEE Transactions on Semiconductor Manufacturing addresses the challenging problems of manufacturing complex microelectronic components.

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Editor-in-Chief

Anthony Muscat
Department of Chemical and Environmental Engineering
Harshbarger Bldg., Room 134
1133 E. James Rogers Way
University of Arizona
Tucson, AZ  85721