Evaluation of Preventive Maintenance Effectiveness with Application to Semiconductor Manufacturing

Preventive Maintenance (PM) plays an essential role in semiconductor manufacturing, in keeping the equipment in control and performing in the long term.  With the advances in semiconductor manufacturing, PM activities become more complex in nature and consist of more tasks, thus taking longer in duration.  This creates a major gap in the ability to proactively evaluate whether a specific PM activity is going to be effective, i.e. enable smooth operation of the equipment without interruption until its next scheduled PM.  In this paper, we propose a new leading metric for the evaluation of PM effectiveness.  We devise the metric based on statistical analysis of historical data and provide validations and insights for our results.

In order to compete in today`s aggressive markets, factories must continuously improve performance of their equipment.  Equipment availability is a significant indicator to ensure factory functionality, productivity and profitability. Higher equipment availability can be achieved by improving equipment uptime which in-turn can be achieved by minimizing their downtime. 

Maintenance activity is one of the main reasons for downtime and can be described as the set of actions performed on equipment with the purpose of allowing the equipment to continue to function exactly as it was designed to.  Preventive Maintenance (PM) is a scheduled maintenance activity that is typically initiated based on statistical parameters (e.g. average time or usage) to determine when the maintenance activity is needed, prior to entering the “risk zone” in which probability to random failure increases.  Evaluation of the PM activity is most needed in order to ensure resource utilization, minimal downtime and higher availability.

The extensive literature suggests multiple key performance indicators (KPIs) but they all suffer by being lagging indicators and do not provide meaningful and proactive insights on the effectiveness of a specific PM activity.

In order to improve equipment performance, and subsequently improve resource utilization and minimal tool downtime, a leading indicator for PM effectiveness is needed.  Such an indicator should reflect and place the right focus on performance, identification of gaps or trends, and ultimately assist managers and technicians in performing the maintenance activity more efficiently and with higher quality.

In this work, we first establish the lack of existing PM effectiveness indicators in the existing literature on measurement of specific PM activity.  We shall then provide an analysis of several indicators with respect to their ability to indicate whether a specific PM activity has been executed with high effectiveness, i.e. performed adequately to be able to sustain the equipment at minimal downtime until its next scheduled PM.

Finally, we establish a framework for a new leading metric for PM effectiveness.