# An Efficient Analytical Approach to Visualize Text-Based Event Logs for Semiconductor Equipment
## 1 Introduction  
Many semiconductor equipment manufacturers store everything that occurs during the operation of the equipment in a log [1,2]. The log contains valuable information that helps understand the system execution status and accurately identifies system errors. In addition, engineers monitor system and equipment debugging for abnormal operations and errors and include process progress information for future debugging and analysis [3]. The Log stores all the information generated from various modules (e.g., Process Module, Transfer Module, Individual Components) that compose the equipment. Logs are not standardized, and some equipment manage different log levels depending on the equipment manufacturer. In general, there are the EventLog, the Process Log, the Alarm Log, the Lot History Log, and the Debug Log. The EventLog stores everything according to the passage of time and is organized as a time series. The EventLog is text-based, so it is hard to see. In the case of a long process, it is composed of several files, and it takes a long time to analyze because it is necessary to understand the relationship between many files [4,5]. The Process Log records information of the parameters related to recipes while the process is in progress. The items included in the Process Log are generally provided with functions to be defined by the user, and the Process Log is created based on the defined items. The Alarm Log consists of Error, Warning, and Information and stores the contents of all alarms that have occurred in the equipment. In terms of troubleshooting, when an alarm occurs, the equipment can clear several alarms while the engineer is taking action. If the user selects the wrong options, the alarm remains unresolved, and it has become a common practice to capture various user interactions in the EventLog and store them in a log file for later analysis [6,7]. The Lot History Log contains the history information ofthe lot in the equipment. Users can check information about the progress history through this log. The Debug Log contains detailed information for troubleshooting when there is a problem with the device. For example, there are Code Level Stack Dump and Snapshot logs. In general, there is a System Debug Log for debugging when a problem occurs in the system, and the Debug Log at the module level is used for each module as needed. Various types of logs are suitable for various purposes, and the contents and types of logs can vary significantly from system to system, even between components within the system. The Event Log is the most common. It stores all contents that occur while all equipment companies operate equipment. The Event Log is usually the first log that engineers check to determine the cause of a problem in the equipment. The Event Log has a vast amount of logging as all the history of the equipment has been stored, and it is difficult to grasp the exact causal relationship because events that have occurred in multiple modules are recorded in one log. Additionally, if the problem occurred in the past, it is often difficult to analyze. In some cases, analyzing a problem device and several devices that do not have a specific time may exceed human analysis capabilities. In terms of log file size, when saving text-based logs, it is necessary to minimize the file size and efficiently save and manage it. Despite the enormous value hidden in the log files, how to analyze them effectively remains a big challenge [8]. This study started with the idea that engineers had difficulties with text log analysis and visualizing the text-based EventLog would help engineers analyze it. Customers are requesting more sensor data at a faster cycle. The saved text-based EventLog is compressed and stored on the hard disk. In particular, the disk size of computers that have been used in the past is not large. So, many types of equipment are using the minimum period of keeping it. If an EvnetLog file becomes oversized, this reduces the period that it can be kept.