Akiko Kagatsume

Reduction of pumping time for a sputtering system by glow discharge cleaning

Sputtering systems for semiconductor manufacturing require high‐vacuum conditions. Typically it takes a long time to recover high‐vacuum conditions after a sputtering system is opened to air. To increase the operating efficiency of the system, the recovery time must be reduced. Therefore, in this study, a glow discharge cleaning technique is applied using a glow‐mode plasma source in argon gas. The discharge current distribution inside the sputtering system is measured under various conditions. It was found that nonuniformity was decreased: when the number of electrodes was increased from one to two; when the pressure during the discharge was decreased to 3×10−3 Torr; and when the anode current or anode voltage was increased. By applying these results, a drastic reduction in pumping time is achieved. The pumping time to attain a pressure of 1.5×10−6 Torr is reduced from 17 to 6 h with concurrent use of 3.5 h of discharge cleaning.

Properties of SiGe Films Fabricated by Reactive Thermal Chemical Vapor Deposition Using Lamp Heating

The structural and electrical properties of SiGe films deposited by reactive thermal chemical vapor deposition using a lamp heating system with a source gas mixture of GeF4 and Si2H6 were investigated. In the SiGe film depositions with respective GeF4 and Si2H6 flow rates of 0.06 and 3 sccm, the film structure changed from crystalline to amorphous during the film growth. The results of secondary ion mass spectroscopy analysis and high-temperature deposition suggest that the gas phase reactions cause the structural change. To suppress the gas phase reactions, low-pressure depositions are investigated. The SiGe film deposited at a relatively low pressure of 400 Pa shows good crystallinity. The thin-film transistor with this SiGe film also reveals a high p-channel mobility of about 10 cm2V-1s-1.

Study on SiGe Film Properties Fabricated using a Reactive Thermal CVD Method

1 Materials Research Laboratory, Hitachi, Ltd. Hitachi-shi, 319-1292 Japan Phone: +81-294-52-7555, Fax: +81-294-52-7615, e-mail: masatoshi.wakagi.vd@hitachi.com 2 Central Research Laboratory, Hitachi, Ltd. Kokubunji-shi, 185-8601 Japan 3 Mechanical Engineering Research Laboratory, Hitachi, Ltd. Hitachinaka-shi,312-0034 Japan 4 Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, Yokohama-shi, 226-8530 Japan