This disclosure relates to methods of forming bipolar transistors, such as heterojunction bipolar transistors. The methods may include forming a sub-collector over a substrate, forming a first portion of a collector over the sub-collector and doping a second portion of the collector to form a doping spike. The method may further include forming a third portion of the collector over the doping spike and forming a base of the bipolar transistor over the third portion of the collector.

This disclosure relates to bipolar transistors, such as heterojunction bipolar transistors, having at a doping spike in the collector. The doping spike can be disposed relatively near an interface between the collector and the base. For instance, the doping spike can be disposed within half of the thickness of the collector from the interface between the collector and the base. Such bipolar transistors can be implemented, for example, in power amplifiers.

Metal pillars are placed adjacent to NPN transistor arrays that are used in the power amplifier for RF power generation. By placing the metal pillars in intimate contact with the silicon substrate, the heat generated by the NPN transistor arrays flows down into the silicon substrate and out the metal pillar. The metal pillar also forms an electrical ground connection in close proximity to the NPN transistors to function as a grounding point for emitter ballast resistors, which form an optimum electrothermal configuration for a linear SiGe power amplifier.

Metal pillars are placed adjacent to NPN transistor arrays that are used in the power amplifier for RF power generation. By placing the metal pillars in intimate contact with the silicon substrate, the heat generated by the NPN transistor arrays flows down into the silicon substrate and out the metal pillar. The metal pillar also forms an electrical ground connection in close proximity to the NPN transistors to function as a grounding point for emitter ballast resistors, which form an optimum electrothermal configuration for a linear SiGe power amplifier.

Solder bumps are placed in direct contact with the silicon substrate of an amplifier integrated circuit having a flip chip configuration. A plurality of amplifier transistor arrays generate waste heat that promotes thermal run away of the amplifier if not directed out of the integrated circuit. The waste heat flows through the thermally conductive silicon substrate and out the solder bump to a heat-sinking plane of an interposer connected to the amplifier integrated circuit via the solder bumps.

Metal pillars are placed adjacent to NPN transistor arrays that are used in the power amplifier for RF power generation. By placing the metal pillars in intimate contact with the silicon substrate, the heat generated by the NPN transistor arrays flows down into the silicon substrate and out the metal pillar. The metal pillar also forms an electrical ground connection in close proximity to the NPN transistors to function as a grounding point for emitter ballast resistors, which form an optimum electrothermal configuration for a linear SiGe power amplifier.

A semiconductor device includes a bipolar junction transistor (BJT) structure including emitters in a first well having a first conductive type, collectors in respective second wells, the second wells having a second conductive type different from the first conductive type and being spaced apart from each other with the first well therebetween, and bases in the first well and between the emitters and the collectors. The BJT structure includes active regions having different widths that form the emitters, the collectors, and the bases.

Device structures for a bipolar junction transistor. A layer is formed on a top surface of a substrate. A trench is formed in the layer and has a plurality of sidewalls with a width between an opposite pair of the sidewalls that varies with increasing distance from the top surface of the substrate. A collector pedestal of the bipolar junction transistor is formed in the trench.

This disclosure relates to bipolar transistors, such as heterojunction bipolar transistors, having at a doping spike in the collector. The doping spike can be disposed relatively near an interface between the collector and the base. For instance, the doping spike can be disposed within half of the thickness of the collector from the interface between the collector and the base. Such bipolar transistors can be implemented, for example, in power amplifiers.

An open base transistor has an emitter region of a first doping polarity, a collector region of the first doping polarity, a base region of a second polarity different from the first doping polarity, and an additional region of the first doping polarity. The base region is resistively connected to the additional region via a resistor.