Search

Three-dimensional stacked memory has attracted much attention due to its advantages such as high-speed operation, low-power consumption, and high-level integration. Many researchers have reported various novel approaches to achieve three dimensional device integration, including wafer bonding, epitaxial lateral overgrowth (ELO), zone melting recrystallization (ZMR), and lateral-solid phase epitaxy (L-SPE). These methods have some limitations, in terms of the requirement of stacked memory process which include simple integration process, low thermal budget due to the performance degradation of underlying devices and single crystalline quality on oxide. In this work, we suggest a laser-induced epitaxial growth (LEG) process that utilizes a single crystalline seed grown by selective epitaxial growth (SEG) process. This seed layer was formed in patterned contact holes linking the substrate Si and the stacked layer. A raised seed could prevent the degradation of electrical properties of underlying devices. An excimer laser was then used as a light source of the epitaxial growth via recrystallization to melt the deposited amorphous Si films both on oxide layer and seed contact during several nano-seconds.

In this study, SiBN films were prepared by plasma assisted atomic layer deposition (PAALD) using dichlorosilane, boron trichloride and ammonia as source gases. In this material system, the reaction control of boron, silicon and nitrogen is a key issue because nitrogen reacts more readily with boron than with silicon. On the other hand, ammonia radicals created by remote plasma during PAALD enhance the reaction between silicon and nitrogen. Therefore, PAALD enables an enhanced controllability of silicon and boron contents. SiBN films with dielectric constant of 4.45 to 5.47 were applied to buried- contact (BC) spacer instead of SiN films in 70 nm DRAM device, and 12 - 24% reduction of bit-line loading capacitance (CBL) was obtained. Low-k SiBN films using PAALD are promising materials for insulating interlayer such as Si3N4 spacer for future sub-70 nm DRAM devices.

Surface roughening and defect formation of (100) Si at low temperatures during electron cyclotron resonance hydrogen plasma cleaning are studied in an ultrahigh vacuum environment, and a new model is proposed to explain their mechanisms. The effect of process parameters on surface roughness is quantitatively analyzed by atomic force microscopy and reflection high energy electron diffraction. Crystalline defect morphology is studied by transmission electron microscopy to understand its role in surface roughness. Surface roughness is strongly related to {111} platelet defects at the Si subsurface region and subsequent preferential etching at positions where {111} platelet defects intersect the Si surface. The formation of {111} platelet defects is determined by the subsurface hydrogen concentration, which is determined by incident hydrogen flux and substrate temperature. The preferential nucleation of etching reactions on the {111} platelet may be explained by the classical nucleation theory. Hydrogen ion flux and substrate temperature can be controlled successfully to tailor {111} platelet defect formation and hence, surface roughness.

Thin films of LiMn[sub 2]O[sub 4] spinel were fabricated by RF magnetron sputtering. The as-deposited films were amorphous but could be crystallized into a spinel structure by rapid thermal annealing in an oxygen atmosphere. The electrochemical performance of 2000 [angstrom] thick LiMn[sub 2]O[sub 4] thin-film cathodes were tested in a LiMn[sub 2]O[sub 4]/1M LiClO[sub 4] in PC + DME/Li cell. LiMn[sub 2]O[sub 4] spinel films prepared at 750 C showed good intercalation kinetics and very promising cycling behavior. Room temperature cycling of these films had capacities of about 50 [mu]Ah/cm[sup 2]-[mu]m at 200 [mu]A/cm[sup 2] and maintained more than 98% of their original capacity after more than 1000 cycles.

not Available.

HfO 2 films were deposited via Hf(OtBu) 4 precursor and ozone oxidant using atomic layer deposition (ALD) atop Al 2 O 3 . We report the impact of annealing conditions on the physical and electrical properties of a HfO 2 on Al 2 O 3 /SiN/Si substrate using medium-energy ion scattering spectroscopy, high-resolution transmission electron microscopy, thermal desorption spectra, and electrical measurements. Annealing temperatures influence the microstructure and impurity levels of Hf(OtBu) 4 HfO 2 /Al 2 O 3 /SiN films. The leakage currents of Al 2 O 3 -HfO 2 bilayer were decreased with the increase of annealing temperature and the structures of the bilayer did not break until 850°C. This change was closely related to the reduction of carbon and organic contamination during annealing. However, annealing at 950°C drastically degraded electrical properties due to the intermixing of the HfO 2 -Al 2 O 3 bilayer structure.