A simple method of photomask yield optimization by defect inspection

The quality of the photomask set decides to a large extent the quality and quantity of the device that will be produced. In order to ensure the quality of the photomasks, several sophisticated instruments are commercially available. However, in a research type of environment, the cost of such equipment can be prohibitive. In this paper, we propose a simple method of multiple master mask preparation with subsequent matching of defective die locations to optimize the master mask set. The advantage here is that a very good master mask set can be chosen so that minimum number of dies on the photomask set itself contribute to low wafer yield. The method is based on manual inspection of individual dies on photomasks and can be practically used for a complexity of up to 500 components.     

Amorphous semiconductors: Structural models

The structure of amorphous semiconductors has become the subject of intense study in recent years. In this paper, the models, that have been constructed and applied to represent the structures, have been briefly reviewed. Details of the construction of continuous random network (CRN) models have been presented and a comparative study of the microcrystallite model and the random network model has been made in the light of their recent applications.     

Cost function analysis of a 3-state reparable system

This paper presents the cost function analysis of a system with 3 states: good, degraded and failed. The system suffers from two types of failure: partial and catastrophic. The partial and catastrophic failures bring the system to degraded and failed state respectively. There is only one server, which is always available. The failure and repair times for the system follow exponential and general distributions respectively. Laplace transforms of various probability states are obtained along with steady-state behaviour of the system. A numerical example has also been discussed to highlight the important results.     

Reliability analysis of a three-state multi-component warm standby redundant complex system with waiting for repair

Investigations have been carried out with the help of Laplace transforms and supplementary variable techniques for the evaluation of reliability analysis of a three-state multi-component warm standby redundant complex system suffering three types of failures, namely minor, major, and human due to critical human errors incorporating the concept of waiting for repair.     

Effects of homogeneous and heterogeneous reactions on the dispersion of a soluble matter in a MHD channel flow

An analysis of the dispersion of a solute in an incompressible, viscous, electrically conducting fluid flowing between two non-conducting plates, under the action of a transverse magnetic field has been carried out on the assumption of an homogeneous irreversible first-order chemical reaction and heterogeneous reaction. Expressions for the effective Taylor diffusion coefficient have been derived in both cases. It is observed that the effective Taylor diffusion coefficient decreases due to an increase in the homogeneous reaction rate constant and also due to an increase in the heterogeneous reaction at the catalytic walls. An increase in$\text{M}$, the Hartmann number, leads to a decrease in the effective Taylor diffusion coefficient whereas an increase in $\text{K}$, the loading parameter, leads to an increase in the effective Taylor diffusion coefficient.     

An improved lexicographic search algorithm for the flowshop scheduling problem

This paper describes an improved lexicographic search algorithm for the solution of the n-job, M-machine flowshop scheduling problem. The proposed improved algorithm is capable of generating all optimal schedules for any monotonically non-decreasing optimality criterion and is computationally more efficient than the basic lexicographic search algorithm. A numerical example is solved to illustrate the decrease in the computational effort by the proposed algorithm.     

Design of reinforced concrete structures subjected to three components of earthquake

The effects of three earthquake components are usually combined using the square root of the sum of the squares (SRSS) method. In this paper, strength criteria have been developed for reinforced concrete structures subjected to three earthquake components using the SRSS method of combining the effects as the basis.     

Radiation resistance of a square loop in a warm plasma

A linearised hydrodynamic theory has been used to calculate the radiation resistance of a square-loop antenna in a warm plasma. It is suggested that cosinusoidal currents of two different propagation coefficients and amplitudes are simultaneously and independently present. Comparisons of the theoretical results with the measured values of the radiation resistance of a square-loop antenna on Ariel 3 satellite gives the ratio of the amplitudes of the currents in the two modes, for various values of the ratio of plasma to measuring frequency.     

Stochastic analysis of a two-unit parallel system with partial and catastrophic failures and preventive maintenance

This paper studies a two-unit parallel system with each unit having two types of failure and two modes of operation—normal or partial failure mode. A unit fails either due to change in operating characteristics or due to catastrophe. The system goes for preventive maintenance randomly (in time). Failure rates are constant while repair and (preventive) maintenance rates are general. Using the theory of regenerative and Markov-renewal processes several important measures of reliability are obtained.     

Design of exclusive or sum-of-products (ESP) logic arrays with universal tests for detecting stuck-at and bridging faults

The detection problem of bridging faults in AND-EXOR arrays is considered in this paper in a new framework. These AND-EXOR arrays are different from the arrays based on the so-called Reed-Muller canonic (RMC) expansion of functions. The multiple stuck-at fault detection test set in such arrays as already derived by Pradhan[1] has been utilized to detect bridging faults. One most important advantage of this test set is that it is independent of the function realized and it has a simple algebraic structure and hence can be generated easily. As this conventional test set is insufficient to detect all bridging faults, we propose a technique of augmenting the network with some additional observation points which take care of otherwise undetectable bridging faults.