El Mostafa El Adel

Generalization and analysis of sufficient conditions for PCA-based fault detectability and isolability

Abstract Fault detectability and fault isolability concepts are necessary to be developed in order to determine whether the process faults are detectable and isolable. In PCA framework, the development of these concepts has been limited to the use of some particular detection indices. This paper provides an extension and a generalization of the fault detectability and the reconstruction-based fault isolabilty concepts in order to be valid for the use of any detection index having a quadratic-form. Fundamental fault detectability as well as fault isolability analyses based on the combined index compared to those using both SPE and Hotelling’s T2 indices are investigated. In addition, we have illustrated the proposed analyses from a simulation example. This one highlights the advantage of the combined index into the isolation of some process faults that have not large enough magnitudes to be isolable neither by SPE index nor by Hotelling’s T2 statistic.

Virtual Metrology applied in Run-to-Run Control for a Chemical Mechanical Planarization process

This paper deals with missing data in semiconductor manufacturing derived from a measurement sampling strategies. The idea is to construct a virtual metrology module to estimate non measured variables using a new modified Just-In-Time Learning approach (JITL). The aim of this paper is to integrate estimated data into product control loop. In collaboration with our industrial partner STMicroelectronics Rousset, the accuracy of the proposed method is illustrated by using industrial data-sets derived from Chemical Mechanical Planarization (CMP) process that enables us to compare results obtained with the classical and the modified version of JITL approach. Then, the contribution of the estimated data is shown in product quality improvement.

Self-tuning of dEWMA controller parameters for mixed product processes with equipment aging

This paper presents an iterative approach which provides a sub-optimal solution of the best achievement performance in the case of closed-loop aged-based processes applied on semiconductor manufacturing industry. The aim is to provide an online parameter estimation of dEWMA Controller in the case of mixed product Run-to-Run (RtR) control. The online estimation is done without any a priori knowledge of process parameters and noise structure. The best achievement performance improvements is illustrated using a simulation problem from literature. The example is applied on the removal rate control in a Chemical Mechanical Polishing (CMP) process.

Virtual metrology based on relevant feature extraction and just-in-time learning approach

This paper focuses on virtual metrology in semiconductor manufacturing. Virtual metrology is requested to deal with the lack of physical measures by their estimations. This lack is due to measurement sampling strategies which aim to reduce the number of physical measurements which are time consuming and expensive. The idea is to estimate missing physical measurement using relevant features extracted from collected and non sampled data and using Just-in-time learning approach.