Showing papers by "Rajesh Kumar Malhan published in 2006"

Power electronic package having two substrates with multiple semiconductor chips and electronic components

Abstract: A power electronic package includes: first and second high thermal conductivity insulating non-planar substrates; and multiple semiconductor chips and electronic components between the substrates. Each substrate includes multiple electrical insulator layers and patterned electrical conductor layers connecting to the electronic components, and further includes multiple raised regions or posts, which are bonded together so that the substrates are mechanically and electrically connected. The number, arrangement, and shape of the raised regions or posts are adjusted to have mechanical separation between the substrates. The electrical conductor layers are separated and isolated one another so that multiple electric circuits are provided on at least one of the substrates.

Power electronic package having two substrates with multiple electronic components

Abstract: A power electronic package includes: first and second high thermal conductivity insulating non-planar substrates; and a plurality of electronic components mounted on each of the substrates. The substrates are coupled each other at a plurality of bonding regions so that mechanical separation between the substrates is controlled by the number of the bonding regions, an arrangement of the bonding regions, a shape of each bonding region, and a material of the bonding regions. The mechanical separation provides a net axially-directed compressive force in the electronic components.

Structural pattern formation in titanium-nickel contacts on silicon carbide following high-temperature annealing

Abstract: The composition and microstructure of compound contacts to 4H-SiC containing both titanium and nickel were investigated. Samples were prepared by metal evaporation on commercial 4H-SiC wafers followed by rapid thermal annealing (RTA). Contact structures with three different metal deposition sequences were investigated: (A) SiC/Ti(4 nm)/Ni(150 nm); (B) SiC/Ti(100 nm)/Ni(50 nm) and (C) SiC/Ti(4 nm)/Ni(50 nm)/Ti(100 nm). RTA was performed in a vacuum at 800, 925 and 1040 °C for a period of 800 s. X-ray diffraction, Auger electron spectroscopy and transmission electron microscopy were used for the characterization. A distinct spatial separation of nickel silicide and titanium carbide layers was observed in all samples. It was discovered that the final distribution of solid-state reaction products in B- and C-samples was independent of the order of the deposition of the initial metal films. In both samples, a two-phase TiC+C layer was found to be adjacent to the SiC substrate. Factors controlling phase formation and segregation are discussed. A two-stage reaction model is proposed to explain the reaction zone structure formed in the Ni–Ti–SiC system after high-temperature treatment.

SiC Migration Enhanced Embedded Epitaxial (ME3) Growth Technology

Abstract: In this work, we have developed an innovative epitaxial growth process named the “Migration Enhanced Embedded Epitaxial” (ME3) growth process. It was found that at elevated growth temperatures, the epitaxial growth at the bottom of the trenches is greatly enhanced compared to growth on the sidewalls. This is attributed to the large surface diffusion length of reactant species mainly due to the higher growth temperature. In addition, it was found that this high temperature ME3 growth process is not influenced by the crystal-orientation. Similar growth behavior was observed for stripe-trench structures aligned either along the [11-20] or [1-100] directions. No difference was observed in the electrical performance of the pn diodes fabricated on either oriented stripe geometry. The ME3 process can also be used as an alternative to ion-implantation technology for selective doping process.

Structural properties of titanium-nickel films on silicon carbide following high temperature annealing

Abstract: Structural properties of Ni/Ti films deposited on 4H-SiC and annealed at temperatures from 800 to 1040°C have been studied. Films with three different metal deposition sequences were investigated by X-ray diffraction and Auger electron spectroscopy: (A) Ti(100 nm)/Ni(50 nm); (B) Ti(4 nm)/Ni(50 nm)/Ti(100 nm); and (C) Ti(4 nm)/Ni(150 nm). A distinct spatial separation of nickel silicide and titanium carbide layers was observed in all samples. It was discovered that the distribution of the products of the solid state chemical reaction in samples (A) and (B) was independent on the deposition sequence of Ti and Ni layers. The titanium carbide layer located on the interface and covered by the clearly separated nickel silicide layer was detected in both samples after heat treatments.

Silicon carbide ohmic contacts

Abstract: A nanocrystalline graphite layer 16 and a transition metal silicide (eg Ni, Mo, Co, W, Ti silicide) layer 18 are formed on a silicon carbide surface by a solid state reaction between the substrate and the transition metal layer The silicide layer and the graphite layer are removed to expose a modified SiC layer 14 A transition metal layer 20 is deposited on the modified layer to form the ohmic contact Device layers formed after the ohmic region has been defined by the modification of the SiC surface but before the ohmic contact metal 20 is deposited are not exposed to high temperature annealing or outdiffusion from an ohmic contact electrode

Electronic power package for high power electronic device, has two non-planar insulating substrates with high thermal conductivity with electrical conductivity layers which are separated and isolated from each other

Abstract: The package has two non-planar insulating substrates with high thermal conductivity with electrical conductivity layers (7a, 7b, 8a, 8b, 9a, 9b, 9c), which are alternatively stacked. An arrangement of raised regions or posts and a shape of the raised regions or posts are adjusted in such a manner that a mechanical separation is provided between the two non-planar insulating substrates with high thermal conductivity. The electrical conductivity layers are separated and isolated from each other.