Cascaded bipolar junction transistor and methods of forming the same

A device, comprising:

• a substrate;
• a first bipolar junction transistor (BJT) disposed over the substrate, the first BJT comprising:
• a first base region;
• a first emitter region;
• and
• a first collector region;
• a second BJT disposed over the substrate adjacent the first BJT, the second BJT comprising:
• a second base region;
• a second emitter region;
• and
• a second collector region;
• a substrate isolation region surrounding the first and second BJTs;
• and
• an interconnect structure disposed over the first and second BJTs, wherein the interconnect structure comprises:
• a first conductive line electrically connecting the first collector region and the second collector region, wherein the first conductive line comprises a first portion disposed over the substrate isolation region and second portions disposed over the substrate isolation region, wherein the first portion is substantially perpendicular to the second portions.

A cascaded bipolar junction transistor (BJT), comprising:

• a first BJT disposed over a substrate;
• a second BJT disposed over the substrate, wherein the first and second BJTs are asymmetric with respect to a portion of a region disposed between the first BJT and the second BJT;
• a first substrate isolation region surrounding the first BJT, wherein the first substrate isolation region comprises a first side, a second side opposite the first side, a third side connecting the first and second sides, and a fourth side opposite the third side;
• a second substrate isolation region surrounding the second BJT, wherein the second substrate isolation region comprises a fifth side, a sixth side opposite the fifth side, a seventh side connecting the fifth and sixth sides, and the fourth side, wherein the fourth side is longer than the third side, and the fifth side is longer than the first side;
• and
• an interconnect structure disposed over the first BJT and the second BJT, wherein the interconnect structure comprises:
• a first conductive line electrically connected to an emitter region of the first BJT and a base region of the second BJT;
• and
• a second conductive line electrically connected to a collector region of the first BJT and a collector region of the second BJT, wherein the second conductive line comprises two parallel first portions connected by a second portion substantially perpendicular to the two parallel first portions when viewed from top.