Provided is a method for manufacturing a semiconductor device that improves the reliability of the semiconductor device. An opening is formed in an insulating film formed over a semiconductor substrate. At that time, a mask layer for formation of the opening is formed over the insulating film. The insulating film is dry etched and then wet etched. The dry etching step is finished before the semiconductor substrate is exposed at the bottom of the opening, and the wet etching step is finished after the semiconductor substrate is exposed at the bottom of the opening.

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 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.

Provided in the present invention is a trench gate power MOSFET (TMOS/UMOS) structure with a heavily doped polysilicon source region. The polysilicon source region is formed by deposition, and a trench-shaped contact hole is used at the source region, in order to attain low contact resistance and small cell pitch. The present invention may also be implemented in an IGBT.

An electrostatic discharge (ESD) protection device is disclosed including at least an NPN transistor and a PNP transistor coupled between a first node and a second node, wherein the ESD protection device may be configured to sink current from the first node to the second node in response to an ESD event. The transistors may be coupled such that a collector of the NPN may be coupled to the first node. A collector of the PNP may be coupled to the second node. A base of the NPN may be coupled to the emitter of the PNP. An emitter of the NPN may be coupled to a base of the PNP.

Provided are a power device having an improved field stop layer and a method of manufacturing the same. The method can include performing a first ion implant process by implanting impurity ions of a first conductive type into a front surface of a semiconductor substrate to form an implanted field stop layer where the semiconductor substrate is the first conductive type. The method can include performing a second ion implant process by implanting impurity ions of the first conductive type into a first part of the implanted field stop layer such that an impurity concentration of the first part of the implanted field stop layer is higher than an impurity concentration of a second part of the implanted field stop layer.

A method of producing a semiconductor device is presented. The method comprises: providing a semiconductor substrate having a surface; epitaxially growing, along a vertical direction (Z) perpendicular to the surface, a back side emitter layer on top of the surface, wherein the back side emitter layer has dopants of a first conductivity type or dopants of a second conductivity type complementary to the first conductivity type; epitaxially growing, along the vertical direction (Z), a drift layer having dopants of the first conductivity type above the back side emitter layer, wherein a dopant concentration of the back side emitter layer is higher than a dopant concentration of the drift layer; and creating, either within or on top of the drift layer, a body region having dopants of the second conductivity type, a transition between the body region and the drift layer forming a pn-junction (Zpn). Epitaxially growing the drift layer includes creating, within the drift layer, a dopant concentration profile (P) of dopants of the first conductivity type along the vertical direction (Z), the dopant concentration profile (P) in the drift layer exhibiting a variation of a concentration of dopants of the first conductivity type along the vertical direction (Z).

The present application teaches, inter alia, methods and circuits for operating a B-TRAN (double-base bidirectional bipolar junction transistor). Exemplary base drive circuits provide high-impedance drive to the base contact region on the side of the device instantaneously operating as the collector. (The B TRAN is controlled by applied voltage rather than applied current.) Current signals operate preferred implementations of drive circuits to provide diode-mode turn-on and pre-turnoff operation, as well as a hard ON state with low voltage drop (the transistor-ON state). In some preferred embodiments, self-synchronizing rectifier circuits provide adjustable low voltage for gate drive circuits. In some preferred embodiments, the base drive voltage used to drive the c-base region (on the collector side) is varied while base current at that terminal is monitored, so no more base current than necessary is applied. This solves the difficult challenge of optimizing base drive in a B-TRAN.

A symmetrically-bidirectional bipolar transistor circuit where the two base contact regions are clamped, through a low-voltage diode and a resistive element, to avoid bringing either emitter junction to forward bias. This avoids bipolar gain in the off state, and thereby avoids reduction of the withstand voltage due to bipolar gain.

An electrostatic discharge protection clamp includes a substrate and a first electrostatic discharge protection device over the substrate. The first electrostatic discharge protection device includes a buried layer over the substrate. The buried layer has a first region having a first doping concentration and a second region having a second doping concentration. The first doping concentration is greater than the second doping concentration. The first electrostatic discharge protection device includes a first transistor over the buried layer. The first transistor has an emitter coupled to a first cathode terminal of the electrostatic discharge protection clamp. The first electrostatic discharge protection device includes a second transistor over the buried layer. The second transistor has an emitter coupled to a first anode terminal of the electrostatic discharge protection clamp. A collector of the first transistor and a collector of the second transistor are over the first region of the buried layer.