Online Monitoring of Copper Damascene Electroplating Bath by Voltammetry: Selection of Variables for Multiblock and Hierarchical Chemometric Analysis of Voltammetric Data

Abstract

The Real Time Analyzer (RTA) utilizing DC- and AC-voltammetric techniques is an in situ, online monitoring system that provides a complete chemical analysis of different electrochemical deposition solutions. The RTA employs multivariate calibration when predicting concentration parameters from a multivariate data set. Although the hierarchical and multiblock Principal Component Regression- (PCR-) and Partial Least Squares- (PLS-) based methods can handle data sets even when the number of variables significantly exceeds the number of samples, it can be advantageous to reduce the number of variables to obtain improvement of the model predictions and better interpretation. This presentation focuses on the introduction of a multistep, rigorous method of data-selection-based Least Squares Regression, Simple Modeling of Class Analogy modeling power, and, as a novel application in electroanalysis, Uninformative Variable Elimination by PLS and by PCR, Variable Importance in the Projection coupled with PLS, Interval PLS, Interval PCR, and Moving Window PLS. Selection criteria of the optimum decomposition technique for the specific data are also demonstrated. The chief goal of this paper is to introduce to the community of electroanalytical chemists numerous variable selection methods which are well established in spectroscopy and can be successfully applied to voltammetric data analysis.

Review—Management of Copper Damascene Plating

“…The first objective is reached by employing for the calibration calculation methods that rely on two-way data chemometric decomposition techniques, 44 including hierarchical techniques, 48 along with multi-way methods. 49 An emphasis is put on aspects of variable selection 50 as well as transference of the master calibration analytical model calculated for the primary instrument to secondary instruments. 51 Also, methods for mitigation of adverse temperature effect on voltammograms are elaborated upon extensively.…”

The Influence of Leveler on the Impurity Behavior of Electroplated Cu Films During Laser Annealing

“…3 Electrochemical deposition of copper interconnect technology is an essential step in 3D three-dimensional integration. 4,5 With the low electrical resistance, high resistivity to electromigration, admirable chemical, mechanical, and thermodynamic properties, the electroplating copper is an important material to fabricate the metallization layers in the damascene process. [6][7][8][9] Accelerators, inhibitors and levelers must be added to the copper electroplating bath in order to achieve a better filling effect.…”