Microsatellites or simple sequence repeats (SSRs) are co-dominant molecular markers. When we used fluorescent SSR markers to construct a linkage map for the female heterogametic silkworm (Bombyx mori, ZW), we found that some loci did not segregate in a Mendelian ratio of 1:1 in a backcross population. These loci segregated in a 3:1 ratio of single bands compared with double bands. Further examination of band patterns indicated that three types of SSR bands were present: two homozygotes and one heterozygote. In the beginning, we considered to discard these markers. By scoring male and female F1 individuals, we confirmed that these loci were located on the Z chromosome. Using the sex-linked visible mutation sch (K05) and its wild-type (C108), we constructed an F1 male backcross (BC1M) mapping population. The combination of sch backcross and SSR data enabled us to map the SSR markers to the Z chromosome. By adjusting input parameters based on these data, we were able to use Mapmaker software to construct a linkage map. This strategy takes advantage of co-dominant markers for positional cloning of genes on the Z chromosome. We localized sch to the Z chromosome relative to six SSR markers and one PCR marker, covering a total of 76·1 cM. The sch mutation is an important sex-linked visible mutation widely used in breeding of commercial silkworms (e.g. male silkworm selection rearing). Localization of the sch gene may prove helpful in cloning the gene and developing strains for marker-assisted selection in silkworm breeding.

Nickel mono-silicide has been considered a promising silicide candidate for sub-90 nm nodes of integrated circuits manufacturing. To form high-quality nickel mono-silicide as source/drain contact electrodes, a two-step low temperature rapid thermal process has been proposed, in which the as-deposited Ni will react with silicon during a low temperature (<310 °C) first anneal. Due to the lower annealing temperature Ni2Si will form after the first anneal. To better control the silicidation process the growth kinetics of Ni2Si thin film fabricated by solid-state reaction of sputtered Ni thin film on n+/p junction at low temperature is investigated in this paper. It is demonstrated that between 260 and 280 °C the thickness of Ni2Si thin film has a linear rather than parabolic dependence on annealing time. The corresponding activation energy for this linear growth is found to be ∼1.35 eV.

The diffusion barrier properties for ultrathin Ru/Ta and Ru/TaN bilayer structure as the copper diffusion barrier are compared. Cu, Ru, Ta and TaN thin films are deposited by using the ion beam sputtering technique. The experimental results show that the thermal stability of the Cu/Ru/Ta or TaN /Si structure is much more improved than that of the Cu/Ru/Si structure without the interlayer. However, the Cu/Ru/TaN/Si shows better thermal stability than the Cu/Ru/Ta/Si structure, which should be attributed to the amorphous nature of the TaN interlayer. The microstructure evolution of the Cu/Ru/Ta (TaN)/Si structure during annealing is discussed. The results show that the Ru/TaN bilayer can be a very promising diffusion barrier in the future seedless Cu interconnect technology.

In this work, AFM and sheet resistance measurements are used to characterize the thermal stability of thin CoSi2 films. We were particularly interested in the influence of different multilayer structures on the topography and surface roughness. Four different multilayer structures (Co/Si, TiN/Co/Si, Ti/Co/Si and Co/Ti/Si) were investigated. Thermal degradation of CoSi2 formed from a standard Co/Si structure is found to have an activation energy of about 4.2 eV, independent of layer thickness (in agreement with previous results by Alberti et al.). A TiN capping layer is shown to improve the thermal stability. However, if the TiN layer is too thick (e.g. 50 nm), a new failure mode is observed: although the TiN prevents grain boundary grooving of the silicide, the thermal stress induced by the TiN causes the CoSi2 layer to crack. For a Ti capping layer, a strong increase of the thermal stability of the CoSi2 layer is observed, even if the Ti capping layer is removed by a selective etching step after the first RTP annealing. The presence of a very thin Ti-O-N containing layer on the CoSi2surface seems to strongly decrease surface diffusion and in this way reduce the tendency for grain boundary grooving.

A multilayer structure of Co/a-Si/Ti/Si(100) together with Co/Ti/Si(100) is applied to investigate the process and mechanism of CoSi2 epitaxial growth on a Si(100) substrate. The experimental results show that by adding an amorphous Si layer with a certain thickness, the epitaxial quality of CoSi2 is significantly improved. A multi-element amorphous layer is formed by a solid state amorphization reaction at the initial stage of the multilayer reaction. This layer acts as a diffusion barrier, which controls the atomic interdiffusion of Co and Si and limits the supply of Co atoms. It has a vital effect on the multilayer reaction kinetics, and the epitaxial growth of CoSi2 on Si. The kinetics of the CoSi2 growth process from multilayer reactions is investigated.

Ultra-thin epitaxial CoSi2 films formed by Co(3∼5nm)/Ti(1 nm)/Si(100) and Co(3∼5nm)/Si(lnm)/Ti(Inm)/Si are studied. The multilayers are deposited by ion-beam sputtering. Rapid thermal annealing (RTA) is used for silicidation. XRD, RBS, TEM, AFM, four-point probe, I-V and C-V measurements are carried out for characterization. The XRD spectra show the CoSi2 film formed by Co/Ti/Si or Co/Si/Ti/Si solid phase epitaxy has, epitaxial characteristic. XTEM shows that the film is continuous. RBS/Channeling shows that the formed CoSi2 has sharp interface with a minimum channeling yield of Co signal of 40%. AFM shows that the surface of ultra-thin CoSi2 film is smooth with a roughness of nearly 0.7 nm. The Rs∼T relationship shows that the CoSi2 films formed by Co/Si/Ti/Si reaction have the best thermal stability (stable up to 900°C). Those formed by Co/Ti/Si reaction are stable up to 850°C, while those formed by Co/Si reaction are only stable up to 750°C. By fitting the experimental I-V and C-V curves of the epitaxial CoSi2/Si Schottky diodes, barrier heights of around 0.6 eV and close to unity ideality factors are obtained.

Ballistic electron emission microscopy (BEEM) and deep level transient spectroscopy (DLTS) have been used to study the effects of substrate damage introduced by an ion-milling process in PtSi/n-Si Schottky contacts. Argon ions with well-defined energies of 300, 500, 700, 1000, 1500 eV were used to sputter n-type Si substrates in an ion beam sputtering system before metal deposition and silicide formation. Histograms of the PtSi/n-Si Schottky barrier height (SBH) measured by BEEM show that the mean SBH decreases with increasing ion energy, which can be explained as a result of donor-like defects that are introduced by the ion milling treatment. From DLTS measurements, we found direct evidence for the presence of such defects.

The thermal stability of thin CoSi2 films formed from four layered structures: Co/Si, TiN/Co/Si, Co/Ti/Si and TiN/Co/Ti/Si has been studied using four-point-probe (FPP), TEM and RBS/channeling. It is found that thermal instability can be influenced by the polycrystalline structure in CoSi2. Growing epitaxial CoSi2 film on Si (100) using TiN capping and Ti interfacial layers can improve the thermal stability of thin CoSi2 film.

The ion-beam-sputtered polycrystalline SiGe film and its doping properties have been studied. Boron and phosphorus have been doped into the sputtered poly-SiGe film by ion implantation and diffusion. To activate the implanted impurities, both rapid thermal annealing and fiirnace annealing have been used. The electrical measurements show that boron and plhosphorus can be doped into sputtered SiGe films and effectively activated by both ion implantation with post-annealing and diffiision. Hall mobilities as high as 31 cm2/V-s and 20 cm2/V.s have been obtained in B-difflhsed and P-diffused SiGe films, respectively. The x-ray diffraction spectra of the sputtered Sifie filhn show its typical polycrystalline structure with (111), (220) and (311) as the preferential orientations.