Analysis of clean room conditions impact on labor productivity : case study

Woo, Jeyoung
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The semiconductor industry follows what is known as Moore’s Law. Moore’s Law says that every 18 months computer chip storage capacity doubles and the intervals between developments in chip design become shorter and shorter. This is also true for the set dates for construction which are dictated by the semiconductor industry’s needs and production schedule. This paper analyzes the impact of a clean room environment. It scrutinizes daily reports and interviews, based on two data sets that focus on a semiconductor wafer fabrication facility (FAB) construction project. Both data sets involve the same crew working on a FAB construction project in the U.S. Room conditions, however, differ. Aside from such working conditions, all elements for both groups are the same (crew skill level, weather, and season). This research is based on the installation, from February 2010 to January 2011 in Austin, Texas, of an access floor in a semiconductor FAB construction project. The total cost of the project was US$3.6 billion. Generally, a semiconductor FAB has raised access floors because cables and pipes are laid under the floors for maintenance and operation purposes. The data for this paper is derived from the access floor installation. The project manager’s daily progress record documented the changes in labor productivity. The data on the number of crew and work-hours is computed based on this information. Labor productivity is defined here as the relationship between output and the labor time for its production. The formula is as follows: Labor productivity = Output(Quantity) / Input(Work-hours) Eq. (1) This study used Eq. (1) to measure labor productivity for two conditions (working in general conditions and working in a clean room conditions). Labor productivity was computed as follows: the unit of output (quantity) is sq. ft., and the unit of input (work-hours) is hours. The questionnaires and interviews attempted to identify the factors affecting project performance: rework, crew interference, overcrowded work areas, and overtime (Garner, et al., 1979; Tucker, et al., 1980). Each section consisted of yes/no questions and one question seeking the interviewee’s opinion about how each problem was solved. The responses are summarized as follows: The results indicate that, in the clean room environment, labor productivity fell by 28.85%. For future projects, this drop represents additional time and money that should be taken into account in the estimate of costs and the schedule duration. The interviews indicate that labor productivity was affected by other factors such as rework, tool availability, other crews not being finished, overcrowded work areas, as well as access to work area.