Documents Ha, Kwonchul 2 results

"This paper presents a summary of arsenic level statistics from air and wipe samples taken from studies conducted in fabrication operations. The main objectives of this study were not only to describe arsenic measurement data but also, through a literature review, to categorize fabrication workers in accordance with observed arsenic levels. All airborne arsenic measurements reported were included in the summary statistics for analysis of the measurement data. The arithmetic mean was estimated assuming a lognormal distribution from the geometric mean and the geometric standard deviation or the range. In addition, weighted arithmetic means (WAMs) were calculated based on the number of measurements reported for each mean. Analysis of variance (ANOVA) was employed to compare arsenic levels classified according to several categories such as the year, sampling type, location sampled, operation type, and cleaning technique. Nine papers were found reporting airborne arsenic measurement data from maintenance workers or maintenance areas in semiconductor chip-making plants. A total of 40 statistical summaries from seven articles were identified that represented a total of 423 airborne arsenic measurements. Arsenic exposure levels taken during normal operating activities in implantation operations (WAM = 1.6
g m-3, no. of samples = 77, no. of statistical summaries = 2) were found to be lower than exposure levels of engineers who were involved in maintenance works (7.7
g m-3, no. of samples = 181, no. of statistical summaries = 19). The highest level (WAM = 218.6
g m-3) was associated with various maintenance works performed inside an ion implantation chamber. ANOVA revealed no significant differences in the WAM arsenic levels among the categorizations based on operation and sampling characteristics. Arsenic levels (56.4
g m-3) recorded during maintenance works performed in dry conditions were found to be much higher than those from maintenance works in wet conditions (0.6
g m-3). Arsenic levels from wipe samples in process areas after maintenance activities ranged from non-detectable to 146
g cm-2, indicating the potential for dispersion into the air and hence inhalation. We conclude that workers who are regularly or occasionally involved in maintenance work have higher potential for occupational exposure than other employees who are in charge of routine production work. In addition, fabrication workers can be classified into two groups based on the reviewed arsenic exposure levels: operators with potential for low levels of exposure and maintenance engineers with high levels of exposure. These classifications could be used as a basis for a qualitative ordinal ranking of exposure in an epidemiological study. "

"Background
The semiconductor industry is known to use a number of chemicals, but little is known about the exact chemicals used due to the ingredients being kept as a trade secret.
Objectives
The objective of this study was to analyze chemical use using a safety data sheet (SDS) and chemical inventory provided by a major semiconductor company, which operated two factories (A and B).
Methods
Descriptive statistics were obtained on the number of chemical products and ingredients, photoresists, and carcinogens, classified by the International Agency for Research on Cancer (IARC), as well as trade secret ingredients. The total chemical use per year was estimated from chemical inventories mass (kg).
Results
A total of 428 and 432 chemical products were used in factories A and B, respectively. The number of pure chemical ingredients, after removing both trade secret ingredients and multiple counting, was 189 and 157 in factories A and B, respectively. The number of products containing carcinogens, such as sulfuric acid, catechol, and naphthalene was 47/428 (A) and 28/432 (B). Chemicals used in photolithography were 21% (A) and 26% (B) of all chemical products, and more than 97% among them were chemicals containing trade secret ingredients.
Conclusions
Each year, 4.3 and 8.3 tons of chemicals were used per person in factories A and B, respectively. Because of the high level of commercial secrecy and the use of many unregulated chemicals, more sustainable policies and methods should be implemented to address health and safety issues in the semiconductor industry."