A method of forming an IC includes providing a field dielectric in a portion of a semiconductor surface, a bipolar or Schottky diode (BSD) class device area, a CMOS transistor area, and a resistor area. A polysilicon layer is deposited to provide a polysilicon gate area for MOS transistors in the CMOS transistor area, over the BSD class device area, and over the field dielectric for providing a polysilicon resistor in the resistor area. A first mask pattern is formed on the polysilicon layer. Using the first mask pattern, first implanting (I.sub.1) of the polysilicon resistor providing a first projected range (R.sub.P1)<a thickness of the polysilicon layer and second implanting (I.sub.2) providing a second R.sub.P(R.sub.P2), where R.sub.P2>R.sub.P1. I.sub.2 provides a CMOS implant into the semiconductor surface layer in the CMOS transistor area and/or a BSD implant into the semiconductor surface layer in the BSD area.

A semiconductor device includes: an FET structure that is formed next to a looped trench on a semiconductor substrate and that has an n.sup.+ emitter region and an n.sup. drain region facing each other in the depth direction of the looped trench across a p-type base region; a p-type floating region formed on the side of the looped trench opposite to the FET structure; and an emitter connecting part that is electrically connected to the n.sup.+ emitter region and a trench gate provided in the same trench, the emitter connecting part and the trench gate being insulated from each other by the looped trench. The trench gate faces the FET structure, and the emitter connecting part faces the p-type floating region, across an insulating film.

In some aspects of the invention, an n-type field-stop layer can have a total impurity of such an extent that a depletion layer spreading in response to an application of a rated voltage stops inside the n-type field-stop layer together with the total impurity of an n.sup. type drift layer. Also, the n-type field-stop layer can have a concentration gradient such that the impurity concentration of the n-type field-stop layer decreases from a p.sup.+ type collector layer toward a p-type base layer, and the diffusion depth is 20 m or more. Furthermore, an n.sup.+ type buffer layer of which the peak impurity concentration can be higher than that of the n-type field-stop layer at 610.sup.15 cm.sup.3 or more, and one-tenth or less of the peak impurity concentration of the p.sup.+ type collector layer, can be included between the n-type field-stop layer and p.sup.+ type collector layer.

An improvement is achieved in the performance of a semiconductor device. The semiconductor device includes a first trench gate electrode and second and third trench gate electrodes located on both sides of the first trench gate electrode interposed therebetween. In each of a semiconductor layer located between the first and second trench gate electrodes and the semiconductor layer located between the first and third trench gate electrodes, a plurality of p.sup.+-type semiconductor regions are formed. The p.sup.+-type semiconductor regions are arranged along the extending direction of the first trench gate electrode in plan view to be spaced apart from each other.

Bipolar junction transistors including inorganic channels and organic emitter junctions are used in some applications for forming high resolution active matrix displays. Arrays of such bipolar junction transistors are electrically connected to thin film switching transistors and provide high drive currents for passive devices such as organic light emitting diodes.

A diode-connected bipolar junction transistor includes a common collector region of a first conductivity, a common base region of a second conductivity disposed over the common collector region, and a plurality of emitter regions of the first conductivity disposed over the common base region, arranged to be spaced apart from each other, and arranged to have island shapes. The common base region and the common collector region are electrically coupled to each other.

A semiconductor device and manufacturing method achieve miniaturization, prevent rise in threshold voltage and on-state voltage, and prevent decrease in breakdown resistance. N.sup.+-type emitter region and p.sup.++-type contact region are repeatedly alternately disposed in a first direction in which a trench extends in stripe form in a mesa portion sandwiched between trench gates. P.sup.+-type region covers an end portion on lower side of junction interface between n.sup.+-type emitter region and p.sup.++-type contact region. Formation of trench gate structure is such that n.sup.+-type emitter region is selectively formed at predetermined intervals in the first direction in the mesa portion by first ion implantation. P.sup.+-type region is formed less deeply than n.sup.+-type emitter region in the entire mesa portion by second ion implantation. The p.sup.++-type contact region is selectively formed inside the p+-type region by third ion implantation. N.sup.+-type emitter region and p.sup.++-type contact region are diffused and brought into contact.

A method comprises arranging a stack, on a semiconductor substrate, comprising a sacrificial layer and an insulating layer. The insulator layer is at least partially arranged between the semiconductor substrate and the sacrificial layer. A recess is formed within the stack. The recess extends through the stack to the semiconductor substrate so that the recess at least partially overlaps with a surface of the collector region of the semiconductor substrate. The collector region extends from a main surface of the semiconductor substrate into the substrate material. The method further comprises generating a base structure at the collector region and in the recess. The base structure contacts and covers the collector region within the recess of the sacrificial layer. The method further comprises generating an emitter structure at the base structure. The emitter structure contacts and at least partially covers the base structure within the recess of the sacrificial layer.

An IGBT includes a floating P well, and a floating N+ well that extends down into the floating P well. A bottom surface of the floating P well has a waved contour so that it has thinner portions and thicker portions. When the device is on, electrons flow laterally from an N+ emitter, and through a first channel region. Some electrons pass downward, but others pass laterally through the floating N+ well to a local bipolar transistor located at a thinner portion of the floating P type well. The transistor injects electrons down into the N drift layer. Other electrons pass farther through the floating N+ well, through the second channel region, and to an electron injector portion of the N drift layer. The extra electron injection afforded by the floating well structures reduces V.sub.CE(SAT). The waved contour is made without adding any masking step to the IGBT manufacturing process.

A bipolar transistor and a method for fabricating a bipolar transistor are disclosed. In one embodiment the bipolar transistor includes a semiconductor body including a collector region and a base region arranged on top of the collector region, the collector region being doped with dopants of a second doping type and the base region being at least partly doped with dopants of a first doping type and an insulating spacers arranged on top of the base region. The semiconductor body further includes a semiconductor layer including an emitter region arranged on the base region and laterally enclosed by the spacers, the emitter region being doped with dopants of the second doping type forming a pn-junction with the base region, wherein the emitter region is fully located above a horizontal plane through a bottom side of the spacers.