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Semiconductor Manufacturing, IEEE Transactions on

Issue 2 • Date May 1990

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Displaying Results 1 - 7 of 7
  • Integrating CAM and process simulation to enhance on-line analysis and control of IC fabrication

    Page(s): 72 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (724 KB)  

    The integration of a process simulator with a commercial computer-aided manufacturing (CAM) system to provide a set of powerful tools for process analysis, diagnosis, and control is described. The CAM system acts as the interface to the simulator and maintains the simulation control data as part of the process specification. Making process simulation available in a manufacturing environment allows engineers to intuitively investigate the process, thus aiding their understanding of the interrelation of process steps. A microprocessing scenario in an application-specific integrated circuit (ASIC) facility is used to demonstrate how the system can be used to analyze options for corrective processing. It can also be used for documenting processes, to simplify process transfer and implementation, and for investigating the effect of corrective processing on device reliability View full abstract»

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  • How to extract defect densities from distribution

    Page(s): 84 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    A technique is presented for representing a defect density, such as might be found on an integrated circuit. Distributions are a powerful tool for presenting defect distributions for test structures and are convenient for yield analysis and modeling. How the concept of distribution can be extended to give more information on the defects is shown. The power of this approach derives from its invariability to test stricture geometry, which enables direct comparison of data from different structures. It is explained how and why defect distributions measured on test structures can be related to those of other structures, i.e. integrated circuits. The mathematics are simple and lead to a defect density which can be expressed in units of defects per geometric factor per independent variable View full abstract»

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  • EPAS: an emitter piloting advisory expert system for IC emitter deposition

    Page(s): 45 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    Emitter piloting is a difficult diffusion process in IC manufacturing. The decision for the adjustment of the piloting drive cycle is a heuristic-oriented task. An expert system, the emitter piloting advisory system (EPAS), is used at Harris Semiconductor to advise fab operators on how to adjust piloting cycle time for emitters based on knowledge extracted from the most experienced engineer. EPAS consists of an input filter to validate the input parameter values; a knowledge base containing the knowledge extracted from the domain expert; a limited learning mechanism for dynamically calculating a better estimate of initial drive time for the next lot; a convergence control mechanism to control the rule inference so that the result of an inference is always closer to the conclusion; a user facility module containing many LISP-based modules developed to let the expert, engineers, and operators maintain the system by themselves; and a user-friendly interface. One EPAS operation example is provided View full abstract»

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  • Modeling of Novolak-based positive photoresist exposed to KrF excimer laser UV radiation at 248 nm

    Page(s): 37 - 44
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    A model is presented for calculating the local exposure and the development rate for a Novolak-resin naphtoquinone-diazide sensitized photoresist exposed to a KrF excimer laser UV radiation at 248 nm. The measured transmission of the pulsed UV radiation through the resist is presented and compared to the simulated one using the model. Classical bleaching characteristics (i.e. the resist transmittance increases with the dose) are observed at low dose exposure with low energy per pulse. When the dose is increased, the photoresist transmittance reaches a maximum and starts to decrease. This behavior is assumed to be due to UV radiation effect on the resin. The model describes a general photoresist with absorbing components, each with two distinctive initial and postexposure states. The model is applied to the case of a Novolak-based photoresist where the two components are the photoactive compound and the resin View full abstract»

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  • A cluster-modified Poisson model for estimating defect density and yield

    Page(s): 54 - 59
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    A simple modification of the Poisson model that accounts for defect clustering when estimating the defect density and yield of a future product is described. The Poisson yield equation is easy to use and interpret, and the composite model can be extended to a layered model without the difficulties associated with, for example, the negative binomial model. The advantage of the method is that the Poisson model, to which all yield models reduce as yields increase, can continue to be used with less effort than, more convenience than, and at least as good accuracy as other more complicated models View full abstract»

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  • Polysilicon resistor trimming by laser link making

    Page(s): 80 - 83
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    A technique for laser trimming of polysilicon resistors has been developed. In this scheme an undoped polysilicon film is patterned lithographically, and then photoresist patterns are used to prevent doping of certain narrow areas of each resistor during the impurity implant; thus, the protected areas remain insulating after wafer processing. Subsequent laser scanning of the undoped regions can produce precise reductions in resistance by lateral diffusion of dopant impurities. Trimming can be accomplished by changing either the laser power or the position. Q-switched Nd:YAG (1.06-μm wavelength) and second-harmonic (0.53-μm wavelength) radiations have produced successful results. The process was applied to passivated resistors with negligible (perhaps zero) post-trim drift, and the temperature coefficients of resistivity (TCRs) of trimmed resistors can be matched to the TCRs of untrimmed resistors in the same film View full abstract»

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  • The use and evaluation of yield models in integrated circuit manufacturing

    Page(s): 60 - 71
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    The development and refinement of net-die-per-wafer yield models during the past 25 years are reviewed, and the models are tested for accuracy by comparison with actual yield data from seven separate chip companies. Depending on chip size, the more accurate models are the Poisson and the negative binomial. Several models for line yields in wafer fabrication are also covered. For predicting yields of larger-die-area very large-scale integration, the negative binomial model is the more accurate, but its use many require experimental determination of alpha, sometimes called the cluster parameter, versus chip area for the particular process and factory environment of interest. How an Insystems holographic wafer inspection machine can aid this process is described. Financial payback calculations for cleaner processing machines and experience curve effects on yields are also discussed 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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Anthony Muscat
Department of Chemical and Environmental Engineering
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1133 E. James Rogers Way
University of Arizona
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