Inspection Detail

Inspection: 119648343 - Micrel Semiconductor

Inspection Information - Office: Fremont District Office

Investigation Summary

At approximately 11:00 a.m. on April 16, 2005, Employee #1, a maintenance technician employee, was doing a preventive maintenance on an Epitaxial reactor exhaust line. The employer uses the epitaxial process in manufacturing IC chips. The Epitaxial process is growing layer of semiconductor film on substrates or wafers. The growing process is done in an Epi-reactor called ASM and the employer has eight of the machines. Inside the heated process chamber of the reactor, deposition of thin film layer on top of the wafer takes place through decomposition of silicon compound, TCS (Triclorosilane) and Silane. Dopant elements such as Arsine (AsH3) and Diborane (B2H6) are also being introduced to alter the conductivity characteristic of epitaxial layer. As per the ASM Epi-Exhaust chemistry document: "Most Epi deposition processes are approximately 1 percent efficient. Thus, commonly 99 percent of the Silicon introduced into the process chamber finds it way into the exhaust system of the processing tool. Partially decomposed Silicon fragments condense on the chamber walls and in the exhaust plumbing. The exhaust byproducts formed in all Silicon Epi processes becomes unstable when exposed to air. In some cases, pyrophoric properties exist that could ignite these compounds when mechanically or chemically agitated, or through self- ignition". Employee #1 suffered a multiple first-degree and second-degree burns on his right thigh, hands and lower abdomen due to a chemical explosion. Employee #1 was hospitalized.

Keywords: BURN, MAINTENANCE, ABDOMEN, THIGH, EXPLOSION, CHEMICAL BURN