Papers by Keyword: Direct Bonding

Abstract: A monocrystalline diamond substrate was bonded with a Si substrate employing a direct bonding technique. The diamond and Si surfaces were functionalized with hydroxyl (–OH) groups and subsequently bonded by the thermal dehydration reaction across the bonding interface. When a diamond (111) surface was treated with a mixture of H₂SO₄ and H₂O₂, it generated an atomic bond of C–O–Si with an oxygen-plasma-irradiated Si substrate. The bonding technique of diamond using the H₂SO₄/H₂O₂ mixture is expected to contribute to the future integration of diamond and semiconductor substrates because it allows low-temperature bonding in atmospheric air with negligible crystallinity damage.

Abstract: 4H-SiC and SOI substrates were bonded by SiO₂-SiO₂ direct bonding method with diluted HF solution (0.5 wt.%). After the bonding process, the handle layer and the BOX layer of the SOI substrate were etched by TMAH solution, and finally the silicon active layer with a thickness of 1.5 μm was remained on the 4H-SiC substrate. Using this silicon layer, Si photodiodes on 4H-SiC for the radiation hardened image sensors were fabricated and demonstrated.

Abstract: In the last decades, silicon carbide (SiC) based heterostructures have gained a remarkable place in research field due to their exceptional properties. These properties make SiC highly suitable for high temperature, high frequency, and high power electronics applications. The most prominent polytypes (among 200 types) of SiC like 3C-SiC, 4H-SiC and 6H-SiC, have distinctive electrical and physical attributes that make them promising candidates for high performance optoelectronic applications. Silicon (Si) also has been accepted as a promising material for wide range of electronic, optical and optoelectronic applications. Heterostructures fabricated by the direct bonding of SiC polytype and Si may have interesting physical and electrical attributes. In this paper, micro and nano-scale simulations of the nn-heterostructures of Si/4H-SiC and Si/3C-SiC have been done with Silvaco TCAD and QuantumWise Atomistix Toolkit (ATK) softwares respectively. Voltage-current density characteristics of the nanoscale and microscale simulated devices are computed and discussed. In nanoscale devices, the effects of defects due to lattice misplacements (axial displacement of bonded wafers) are also studied. These simulations are the preparation for our future experiments, which are targeted to produce either a high electron mobility diode or a light emitting diode, by direct bonding (diffusion welding) of SiC polytypes.

Abstract: In the last decade, silicon carbide (SiC) has gained a remarkable position among wide bandgap semiconductors due to its high temperature, high frequency, and high power electronics applications. SiC heterostructures, based on the most prominent polytypes like 3C-SiC, 4H-SiC and 6H-SiC, exhibit distinctive electrical and physical properties that make them promising candidates for high performance optoelectronic applications. The results of simulations of nn-junction 3C-4H/SiC and 6H-4H/SiC heterostructures, at the nanoscale and microscale, are presented in this paper. Nanoscale devices are simulated with QuantumWise Atomistix Toolkit (ATK) software, and microscale devices are simulated with Silvaco TCAD software. Current-voltage (IV) characteristics of nanoscale and microscale simulated devices are compared and discussed. The effects of non-ideal bonding at the heterojunction interface due to lattice misplacements (axial displacement of bonded wafers) are studied using the ATK simulator. These simulations lay the groundwork for the experiments, which are targeted to produce either a photovoltaic device or a light-emitting diode (working in the ultraviolet or terahertz spectra), by direct bonding of SiC polytypes.

Abstract: Granulation is a precious metal craft process method that decorates a metal surface using tiny metal granules. It was imported into Korea during the Shilla Dynasty around 1500 years ago, and many granulation ornaments have been found with the process’s unique bonding features. The granules show a direct bonded interface with a neck. The key technology of making granules and bonding the granules is not well known. Thus, it is a technology of the Lost World. Although the exact bonding method is unidentifiable, it is known that the traditional method of preparing gold granules was time consuming and costly. Therefore, we proposed a process to reproduce the Shilla’s granulation ornament using a modern method. First, we employed atomization to produce 22K gold granules. Direct bonding was accomplished using a spot welder and vacuum jig instead of using the traditional method of graphite bed melting and direct annealing. 0.8 mm granules were successfully fabricated and bonded directly to the substrate with a necking and 35% bonding ratio, which is very similar to Shilla’s granule bonding. Moreover, to estimate the bond strength, K factors (fracture toughness index) at different bonding ratios were evaluated using a finite element method simulation. Our proposed direct bonded granule process and design were expected to have enough bond strength to be used as a key element for fine modern jewelry.

Abstract: Experiments to directly bond AlN with Cu were conducted for different pre-treatments of the bonded components. AlN substrates were implanted either with oxygen, or titanium or iron ions at low (15 keV) or high (70 keV) energy, or thermally oxidized. Some Ti-implanted samples were also thermally oxidized. The copper component was annealed and thermally oxidized. The best results, with respect to the bond shear strength, were obtained for low-energy implantation of oxygen and titanium.