Keung Hui

Performance assessment of virtual metrology in APC applications for the viability of sampling reductions

This paper presents a detail investigation on the performances of adopting virtual metrology in applications of advanced process controls for the purpose of sampling reductions to cut down manufacturing costs. The intended application of virtual metrology is to replace hardware measurements instead of as digital gatekeeper or alarm-trigger of invoking advanced process controls. Whereas many feasibility instances have been reported, assessments of virtual metrology actually replacing hardware measurements for advanced process controls are few. This study investigates the performance boundaries that virtual metrology can be applied to advanced process controls without sacrificing process qualities. The limits govern whether virtual metrology can deliver what it is expected and help to map out directions of investment efforts prior to actual implementations.

Case of small-data analysis for ion implanters in the era of big-data FDC

This paper presents a case study of constructing process models based on physical mechanisms of semiconductor manufacturing tools in attempts to predict behaviours of process conditions. Actual measurements from the processing tools are always corrupted with noises and crunching huge volumes of temporal traces of status variables very often fail to pinpoint the accurate fault conditions, not to mention any of their efficient classifications, should abnormal conditions really exist. The current fashion of moving into massive big data computing is yet to distill concrete correlations among tool conditions and impacts on process results of semiconductor devices. As an alternative before the foolproof maturity of big data cracking, and in contrast to the conventional black-box approach of statistical regressions, we take a fundamental view in constructing physical model of the ion implantation process for a flywheel implanter, first to calculate the motion trajectories and subsequently, the implantation dosage on the wafer. We summarize the underlying solution techniques in principles and leave the specific details of parameter calibrations to individual field practitioners.

A failure model of heating filaments in epitaxial growth tools

This paper presents a failure model of heating filaments as used in semiconductor manufacturing tools for growing epitaxial films. Attempts were endeavoured to provide feasible physical insights on the observations in changes of impedance as indirectly derived via readings of voltage-current measurements, instead of conventional data-driven black-box approach of statistical regressions. The proposed model is able to predict the magnitudes of these impedance changes and the classification result lends itself to the setting up of quantifiable control limits to enable early warnings of fault detections in process controls.

Target and uniformity controls of WLP in SSL/LED manufacturing

Advanced process controls (APC) have been ubiquitously applied to the manufacturing processes of semiconductor devices for over two decades by now. Reports on its successful applications to the makings of light-emitting diodes (LED) in the solid-state lighting (SSL) industry however are comparatively less well documented in the literature [1-4]. The concluding remark in [1], ‘…APC is not yet reality … on the right track ….’ precisely summarizes the current state and difficulties of actual practices in reality.