Evidence for self-organized criticality in unscheduled downtime data of equipment

Abstract

How to reduce downtime and improve availability of the complex equipment is very important. Although the unscheduled downtime (USDT) issues of the equipment are very complex, the self-organized criticality (SOC) is the right theory to study complex systems evolution and opens up a new window to the investigation of disasters, such as the sudden failure of the equipment. Firstly, SOC theory and its validation method are introduced. Then an SOC validation method for USDT of the equipment is proposed based on the above theory. Case study is done on bottleneck equipment in a factory and corresponding data pre-process work is done. The rescaled-range (R/S) analysis method is used to calculate the Hurst exponent of USDT time-series data in order to determine the long-range correlation of USDT data on time scale; at the same time the spatial power-law characteristic of USDT time series data is studied. The result shows that the characteristics of SOC are revealed in USDT data of the equipment according to the criterion of SOC. In addition, based on the characteristics of SOC, the overall framework of the prediction method for major sudden failure of the equipment is proposed based on SOC.Keywords: unscheduled downtime (USDT), self-organized criticality (SOC), rescaled-range analysis (R/S), Hurst exponent.

Thermal oxidation improvement in semiconductor wafer fabrication

“…Figure 1 shows the general semiconductor wafer fabrication process flow [16]. After wafer fabrication process, the wafers are sent for probe test to check the electrical distributions and yield, prior to sending to assembly and final test [7,[10][11][12][13][17][18][19][20]. One of the critical process in semiconductor wafer fabrication is the thermal oxidation process [6,8,9,11,12].…”

“…Maintaining the tool uptime has always been a test in the semiconductor manufacturing industry as industry gets more competitive by the day [17,20,[22][23][24][25]. Tool uptime is an important element towards the manufacturing production output [22].…”

“…The plant needs to reduce or eliminate all factors that disrupt its output performance. One of the main focuses is to reduce downtime of critical tools and improve the tools availability [17,23]. This is a very complex area as downtime reduction of critical tools needs intense study that anything done does not affect the after product.…”