In related semiconductor industry, the cleanroom is the production area where very sensitive production process is carried out. One of the production processes that perform in the cleanroom is the specific product testing under tight environmental control including temperature and humidity. The operation of cleanroom with out of specification directly risks in producing defects product. This research project presents the application of cause-effect chain analysis plus (CECA+) method to systematically analyse the problem of cleanroom relative humidity that occurred at a semiconductor industry. The monitoring data of humidity level at one of the cleanroom in the case study company shows the abnormal pattern. Since the application of CECA+ method to solve industry related case studies is very limited, thus this given a motivation in this presented research project. The objective of this study is twofold. The first objective is to perform root cause analysis based on mentioned industry problem by applying the CECA+ method. The second is to implement the proposed solution that come from the analysis process of the first objective. The original version of CECA+ presented in Lee, Chechurin, & Lenyashin (2018) consists of seven steps. In this research project, an improved version of CECA+ that incorporated 5M1E (Man, Method, Material, Measurement, Machine and Environment) for cause chain classification and other two steps added (implementation idea and verify effectiveness of the idea) are presented to optimize the application and implementation of the method. Implementation of action derived from the analysis showing outlined objective was successfully achieved. This study concludes that the need to carry out the root cause analysis in a structured way. The application of CECA+ that presented in this research project successfully guides the discovery process of the problem in a systematic way, thus leads to identify the feasible solution.
