Papers by Author: Akira Izumi

Abstract: We investigated hydrogen radical copper cleaning via the hot-wire method using only a rotary pump for the vacuum exhaust system. The copper oxide surface was successfully reduced. The treatment also increased the resistance of copper to oxidation.

Abstract: Cu has been used as interconnection and lead frame in ULSIs. However, the oxidation and contamination of Cu are not easily avoided. As a result, a thin layer of Cu2O, CuO and carbon contaminations are formed at the Cu surface and these resistances are increased. Therefore, Cu cleaning is necessary. There are some reports to remove Cu oxide layers. Chemical processes such as H2 and NH3 plasma reduction are being investigated [1-5]. These methods have the problem of the plasma damage. Lee et al. proposed Cu oxide reduction using vacuum annealing [6]. However, it seems not suitable for the ULSI process, because the heat-treatment of 400oC is necessary. Therefore, low temperature Cu cleaning without plasma assist is strongly desired. In our previous work, we proposed novel low temperature atomic hydrogen or NH3 decomposed species cleaning generated by heated catalyzer [7,8]. However, in the method it is used 100% hydrogen gas. From the view point of safety, hydrogen gas diluted below explosion limit is preferred to use. In this paper we proposed a novel Cu cleaning method by atomic hydrogen generated on a heated tungsten catalyzer using diluted hydrogen as a cleaning gas.

Abstract: Strained silicon engineering was first used at the 90-nm node. Nowadays, a series of techniques has seen wide-spread use and many derivatives are available because of their ease of integration and cost-effective features [ , ]. As a main part of stressor technique, embedded SiGe-S/D technology is reported to improve the pMOSFET drive current [ , ].

Abstract: Highly transparent silicon carbon nitride (SiCN) films were prepared by hot wire chemical vapor deposition (HWCVD) at low temperature as low as 40oC. Hexamethyldisilazane (HMDS) and NH3 were used as the source materials for SiCN deposition. The SiCN film prepared by only HMDS was completely transparent in the wavelength of the visible region. Moreover, there was a little absorption in the ultraviolet region. However, SiCN prepared by using HMDS and NH3 showed almost transparent both visible and UV regions.