National Semiconductor Corporation

Abdalla Aly Naem

Stepan Essaian

Visvamohan Yegnashankaran

Sandeep Raj Bahl

Reda R Razouk

Chin-Miin Shyu

A copper-topped interconnect structure allows the combination of high density design areas, which have low current requirements that can be met with tightly packed thin and narrow copper traces, and low density design areas, which have high current requirements that can be met with more widely spaced thick and wide copper traces, on the same chip.

Method of forming a copper topped interconnect structure that has thin and thick copper traces

A method includes forming a non-continuous epitaxial layer over a semiconductor substrate. The substrate includes multiple mesas separated by trenches. The epitaxial layer includes crystalline Group III nitride portions over at least the mesas of the substrate. The method also includes depositing a dielectric material in the trenches. The method could also include forming spacers on sidewalls of the mesas and trenches or forming a mask over the substrate that is open at tops of the mesas. The epitaxial layer could also include Group III nitride portions at bottoms of the trenches. The method could further include forming gate structures, source and drain contacts, conductive interconnects, and conductive plugs over at least one crystalline Group III nitride portion, where at least some interconnects and plugs are at least partially over the trenches. The gate structures, source and drain contacts, interconnects, and plugs could be formed using standard silicon processing tools.

Growth of group III nitride-based structures and integration with conventional CMOS processing tools

A copper-compatible fuse target is fabricated by forming a target structure at the same time that a trace structure is formed on a passivation layer, followed by the formation of an overlying non-conductive structure. After the overlying non-conductive structure has been formed, a passivation opening is formed in the non-conductive structure to expose the passivation layer and the side wall of the target structure.

Method of forming a copper-compatible fuse target

A copper-compatible fuse target is fabricated by forming a copper target structure at the same time that the copper traces are formed. After the copper target structure and the copper traces have been formed, a conductive target, such as an aluminum target, is formed on the copper target structure at the same time that conductive connection portions, such as aluminum pads, are formed on the copper traces. A trench is then etched around the copper target structure and conductive target to form a fuse target.

Copper-compatible fuse target

A fuse target is fabricated in a copper process by forming a number of copper targets at the same time that the copper traces are formed. After the copper targets and the copper traces have been formed, metal targets, such as aluminum targets, are formed on the copper targets at the same time that metal bonding pads, such as aluminum bonding pads, are formed on the copper traces.

Fuse target and method of forming the fuse target in a copper process flow

A copper-topped die, which has exposed copper lines and pads, is utilized as the lower die in a stacked die structure. A non-conductive material is formed over the lower copper-topped die, and then selectively removed so that the non-conductive material covers and lies between the copper lines while none of the non-conductive material lies over the copper pads. An upper die is then attached to the non-conductive material.

Stacked die structure with an underlying copper-topped die

Copper-topped interconnect structure that has thin and thick copper traces and method of forming the copper-topped interconnect structure

The vertical diffusion of dopants from the gate and the bulk material into the channel region, and the lateral diffusion of dopants from the source and drain regions into the channel region resulting from thermal cycling during the fabrication of a MOS transistor is minimized by forming the source and drain regions in a layer of composite material that includes silicon, germanium, and carbon.

Method of forming a transistor with a channel region in a layer of composite material

A dual-sided semiconductor device is formed on a wafer with a resistive element that is formed through the wafer. By forming the resistive element through the wafer, a resistive element, such as a large resistive element, can be formed on the wafer that requires very little silicon surface area.

Dual-sided semiconductor device with a resistive element that requires little silicon surface area

The vertical diffusion of dopants from the gate into the channel region, and the lateral diffusion of dopants from the source and drain regions into the channel region resulting from thermal cycling during the fabrication of a MOS transistor is minimized by forming the source and drain regions in a layer of silicon germanium carbon.

Method of forming a MOS transistor with a layer of silicon germanium carbon

The intrinsic base region of a bipolar transistor is formed to avoid a chemical interaction between the chemicals used in a chemical mechanical polishing step and the materials used to form the base region. The method includes the step of forming a trench in a layer of epitaxial material. After this, a base material that includes silicon and germanium is blanket deposited, followed by the blanket deposition of a layer of protective material. The layer of protective material protects the base material from the chemical mechanical polishing step.

Bipolar transistor with an ultra small self-aligned polysilicon emitter

A bipolar transistor structure includes trench isolation dielectric material formed in a semiconductor substrate to define a substrate active device region. A collector region is formed beneath the surface of the active device region. A base region is formed in the active device region above the collector region and extends to the surface of the active device region. A layer of dielectric material is formed to extend at least partially over the trench isolation and over the surface of the base region. A layer of doped polysilicon is formed over the layer of dielectric material and extends over the edge of the layer of dielectric material and over the surface of the base region. The doped polysilicon is patterned to define a polysilicon emitter region that extends over the edge of the layer of dielectric material to provide an ultra-small emitter contact on the surface of the base region. Heating of the doped polysilicon causes dopant to diffuse into the polysilicon emitter contact through the surface of the base region beneath the polysilicon emitter contact. Dielectric sidewall spacers are formed on the sidewalls of the polysilicon emitter region to electrically isolate the polysilicon emitter sidewalls.

Bipolar transistor structure with ultra small polysilicon emitter

MOS transistor and method of forming the transistor with a channel region in a layer of composite material

A low-power bipolar transistor is formed to have an intrinsic emitter region with a sub-lithographic width, and an oxide layer that is self aligned to an overlying extrinsic emitter. The small extrinsic emitter region reduces the maximum current that can flow through the transistor, while the self-aligned oxide layer and extrinsic emitter reduces the base-to-emitter junction size and device performance variability across the wafer.

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Abdalla Aly Naem