Takeshi Senda

Strain relaxation of patterned Ge and SiGe layers on Si(0 0 1) substrates

It was found that patterning of Ge and SiGe layers on Si(001) substrates principally leads to the strain anisotropy. The striped mesa structure readily induces elastic relaxation of the strained Ge and SiGe. Furthermore, a clear difference of strain relaxation mechanism depending on the dislocation introduction was confirmed. Introduction of 60deg dislocations is sensitive to the shape of patterned region, resulting in the anisotropic strain. On the other hand, the pure-edge dislocation network explicitly leads to isotropic strain relaxation even in the miniaturized region

Mechanical Properties and Chemical Reactions at the Directly Bonded Si–Si Interface

Directly bonded interfaces of hydrophilic and hydrophobic Si(100) wafers were studied from the viewpoint of bonding energy and chemical products as a function of the annealing temperature. The experimental results indicated that for both hydrophilic and hydrophobic Si/Si bonded wafer pairs, the behavior of the bubbles at the bonding interface and the bonding energy were closely related to the behavior of the hydrogen and oxygen atoms at the bonding interface. The bonding mechanisms for both cases have been discussed on the basis of the chemical reactions induced by the annealing temperature.

Characterization and Analyses of Interface Structures in Directly Bonded Si(011)/Si(001) Substrates

We investigated the interface structure of directly bonded Si(011)/Si(001) substrates prepared by conventional bonding and grind-back. The interfacial structure was analyzed by transmission electron microscopy (TEM) and in-plane X-ray diffraction (XRD). The plan-view and cross-sectional TEM observations provided evidence that screw dislocation lines were localized to the interfacial plane and that threading dislocations were absent. Grazing-incidence in-plane XRD analyses confirmed the existence of mosaic structures at the interface. These structures were formed because of the deformation field produced by the screw dislocations. This allowed a high level of crystallinity to be maintained in regions away from the interface in both the Si(011) layer and the Si(001) wafer.

Microscopic Structure of Directly Bonded Silicon Substrates

Using X-ray microdiffraction (XRMD) and transmission electron microscopy (TEM) techniques, we have investigated the microscopic structure of Si(011)/Si(001) direct silicon bonding (DSB) substrates. XRMD was performed to measure the local lattice spacing and tilting in the samples before and after oxide out-diffusion annealing. Diffraction analyses for (022) lattice planes with two orthogonal in-plane directions of X-ray incidence revealed anisotropic domain textures in the Si(011) layer. Such anisotropy was also confirmed by TEM in the morphology at the Si(011)/Si(001) bonded interface. The anisotropic crystallinity is discussed on the basis of interfacial defect structures which are proper to the DSB substrate.

Cross‐sectional TEM Observations of Si Wafers Irradiated With Gas Cluster Ion Beams

Irradiation by a Gas Cluster Ion Beam (GCIB) is a promising technique for precise surface etching and planarization of Si wafers. However, it is very important to understand the crystalline structure of Si wafers after GCIB irradiation. In this study, the near surface structure of a Si (100) wafer was analyzed after GCIB irradiation, using a cross‐sectional transmission electron microscope (XTEM). Ar‐GCIB, that physically sputters Si atoms, and SF6‐GCIB, that chemically etches the Si surface, were both used. After GCIB irradiation, high temperature annealing was performed in a hydrogen atmosphere. From XTEM observations, the surface of a virgin Si wafer exhibited completely crystalline structures, but the existence of an amorphous Si and a transition layer was confirmed after GCIB irradiation. The thickness of amorphous layer was about 30 nm after Ar‐GCIB irradiation at 30 keV. However, a very thin (< 5 nm) layer was observed when 30 keV SF6‐GCIB was used. The thickness of the transition layer was the sam...

Strain Relaxation of Patterned Ge and SiGe Layers on Si

It was found that patterning of Ge and SiGe layers on Si(001) substrates principally leads to the strain anisotropy. The striped mesa structure readily induces elastic relaxation of the strained Ge and SiGe. Furthermore, a clear difference of strain relaxation mechanism depending on the dislocation introduction was confirmed. Introduction of 60deg dislocations is sensitive to the shape of patterned region, resulting in the anisotropic strain. On the other hand, the pure-edge dislocation network explicitly leads to isotropic strain relaxation even in the miniaturized region