University of Electronic Science and Technology of China

Third Dimension (3d) Semiconductor, Inc.

Third Dimension Semiconductor, Inc.

Cheng Dian Intelligent-power Microelectronics Design Co., Ltd of Chengdu

University of Elec. Sci. & Tech. of China

University of Eletronic Science and Technology

Xingbi Chen

The present invention relates to a technique of semiconductor devices, and provides a semiconductor device, which uses two controllable current sources to control the electron current and the hole current of the voltage-sustaining region of a thyristor under conduction state, making the sum of the two currents from anode to cathode close to a saturated value under high voltage, thus avoiding the current crowding effect in local region and increasing the reliability of the device. Besides, it further provides a method of implementing the two current sources in the device and a method to improve the switching speed.

Both carriers controlled thyristor

A method or an auxiliary method to implement Optimum Variation Lateral Electric Displacement uses an insulator film(s) containing conductive particles covering on the semiconductor surface. This film(s) is capable of transmitting electric displacement into or extracting it from the semiconductor surface, or even capable of extracting some electric displacement from a part of the semiconductor surface and then transmitting it to another part of the surface. Optimum Variation Lateral Electric Displacement can be used to fabricate lateral high voltage devices, or as the edge termination for vertical high voltage devices, or to make capacitance. It can be further used to prevent strong field at the boundaries of semiconductor regions of different types of conductivity types.

Surface (lateral) voltage-sustaining region with an insulator film containing conductive particles

An IGBT with almost no tail during turning-off is formed by connection of both the base and the emitter of the BJT of the IGBT at the bottom of the chip to two regions in an area of the top surface of the chip. The two regions keep non-depleted even under a maximum voltage being applied across the collector and the base of the BJT. The current through the two regions can be controlled by a gate voltage of a place close to the active region of the MISFET of the IGBT through a surface voltage-sustaining region. The injection efficiency of minorities of the IGBT can thus be controlled.

High speed IGBT

This invention provides a structure for low-voltage power supply in high-voltage devices or IC's made on a semiconductor substrate of a first conductivity type. The structure comprises a heavily doped semiconductor region of the first conductivity type between, but not contacted with, two semiconductor regions of the second conductivity type. When the two semiconductor regions of the second conductivity type have reverse-biased voltage with respect to substrate, the depletion region of substrate reaches the heavily doped semiconductor region of the first conductivity type, the heavily doped semiconductor region of the first conductivity type constructs a terminal of low-voltage power supply and any one of the semiconductor region of the second conductivity type constructs another terminal. The heavily doped semiconductor region is used as one terminal of a primary low-voltage power supply and any other region is used as another terminal of it. Thus, the cost of a low-voltage power supply can be reduced and the electrical performances be improved.

Low voltage power supply

High- and low-side surface voltage sustaining regions are produced utilizing optimum surface variation lateral doping. Schottky junctions are formed by depositing metal (M) on an n-type region having the lowest potential, taking M as the anode Aor Aof the Schottky diode, and ohmic contact is formed at the portion having the highest potential, taken as the cathode Kor Kof the Schottky diode. The potentials refer to a reverse bias applied to the Schottky diode. Each voltage-sustaining region is isolated and can be divided into several sections with isolation region inserted between them. A Schottky diode is formed in each section and connected to each other in series. A lateral Schottky diode and an n-MOST can be formed within a single voltage-sustaining region. The source region and drain region are connected directly to the anode and cathode of the Schottky junction, respectively.

Lateral Schottky diode

This invention provides a lateral high-voltage semiconductor device, which is a three-terminal one with two types of carriers for conduction and consists of a highest voltage region and a lowest voltage region referring to the substrate and a surface voltage-sustaining region between the highest voltage region and the lowest voltage region. The highest voltage region and the lowest region have an outer control terminal and an inner control terminal respectively, where one terminal is for controlling the flow of majorities of one conductivity type and another for controlling the flow of majorities of the other conductivity type. The potential of the inner control terminal is regulated by the voltage applied to the outer control terminal. The figure presented schematically shows a device by using an n-MOSFET to control the flow of electrons and a pnp bipolar transistor to control the flow of holes, and the potential of the base region of the pnp transistor is regulated by the voltage applied to the gate electrode of the n-MOSFET.

Lateral high-voltage semiconductor devices with majorities of both types for conduction

This invention provides a semiconductor device, which is used to manufacture two lateral high-voltage devices on the same substrate, where the voltages between maximum voltage terminals and minimum voltage terminals of the two devices have not too much difference. Both devices are formed on two different surface regions with a small isolation region in-between the two regions. When the semiconductor region(s) of the isolation region is fully depleted, its effective electric flux density emitted to the substrate is of a value between the values of its adjacent regions of said two semiconductor devices. The figure presented here schematically shows the structure used to form a low-side high-voltage n-MOST and high-voltage n-MOST and M, where their terminal voltages are very close.

Semiconductor device

A cell of a semiconductor device comprises a substrate of n-type with a trench formed in a portion of a first main surface of the substrate and filled with insulator. Two device-feature regions are formed beneath the first main surface of the substrate, the first one at one side and the second one at the other side of the trench. A region of a p-type and/or a region of metal is formed in the first device feature region and is connected to a first electrode. A p-n junction is formed in the second device feature region and the p-region of the p-n junction is connected to a second electrode. A U-shaped region is formed between the two device regions. An IGBT without tail during turning-off can be fabricated with a simple process at a low cost.

Semiconductor device with a U-shape drift region

In a chip containing high-voltage device with a semiconductor substrate of a first conductivity type, a method of implementing low-voltage power supply is provided, wherein the electrical potential of an isolated region of a second conductivity type in a surface portion is used as one output terminal or as a voltage by which a transistor is controlled to provide output current for a low-voltage power supply. The other output terminal could be either terminal of the two that apply high voltage to high-voltage device or could be a floating terminal. Using this method, a low-voltage power supply can be implemented not only for the low-voltage integrated circuit (I) in a power IC containing one high-voltage device, but also for the low-voltage integrated circuit in a power IC having totem-pole connection or CMOS connection. As there is no need to implement depletion mode device in the chip, the fabrication cost is reduced.

Method of producing a low-voltage power supply in a power integrated circuit

A semiconductor lateral voltage-sustaining region and devices based thereupon. The voltage-sustaining region is made by using the Metal-Insulator-Semiconductor capacitance formed by terrace field plate to emit or to absorb electric flux on the semiconductor surface, so that the effective electric flux density emitted from the semiconductor surface to the substrate approaches approximately the optimum distribution, and a highest breakdown voltage can be achieved within a smallest distance on the surface. The field plate(s) can be either connected to an electrode or floating ones, or connected to floating field limiting rings. Coupling capacitance between different plates can also be used to change the flux distribution.

Lateral high-voltage devices with optimum variation lateral flux by using field plate

A semiconductor high-voltage device comprising a voltage sustaining layer between a n+-region and a p+-region is provided, which is a uniformly doped n(or p)-layer containing a plurality of floating p (or n)-islands. The effect of the floating islands is to absorb a large part of the electric flux when the layer is fully depleted under high reverse bias voltage so as to the peak field is not increased when the doping concentration of voltage sustaining layer is increased. Therefore, the thickness and the specific on-resistance of the voltage sustaining layer for a given breakdown voltage can be much lower than those of a conventional voltage sustaining layer with the same breakdown voltage. By using the voltage sustaining layer of this invention, various high voltage devices can be made with better relation between specific on-resistance and breakdown voltage.

Semiconductor high-voltage devices

Lateral high-side and low-side high-voltage devices with low specific on-resistances are made in a first and in a second surface voltage-sustaining region, respectively. In the on-state of high-side MOST (the right portion of the figure), the voltage across its source and its drain is very low and only layer(p-type) is depleted to a large extent, layerand layerremain neutral and can serve as drift region(s) of electrons and/or holes. The drift region can be used for a single n-MOST or p-MOST, or even a parallel connection of n-MOST and p-MOST as shown in the figure. In the off-state of the high-side MOST, the voltage across its source and its drain is very large, but the voltage across its drain and the substratecan be very low, and all of the layers in the first surface voltage-sustaining region are depleted, the depleted layerproduces an optimum variation lateral density of charge. The low-side MOST (the left portion of the figure) is similar to the high-side MOST.

Lateral low-side and high-side high-voltage devices

This invention provides a method or an auxiliary method to implement optimum variation lateral flux on a semiconductor surface. The method is to cover one or more thin films of high permittivity dielectric material on the semiconductor surface. The one or more films are capable of transmitting flux into or extracting flux from the semiconductor surface, or even to extract some flux from a part of the semiconductor surface and then transmit the flux to another part of the semiconductor surface. By using optimum variation lateral flux, not only can high-voltage lateral devices be made, but also an edge-termination technique for high-voltage vertical devices is provided. While the thin films can be used to prevent the occurrence of strong electric fields produced at the edges of some doped regions, these regions are used to compensate other doped regions with opposite doping and different location. Thin films can also be used to realize an optimum variation lateral flux of a lateral semiconductor device, which is located on a substrate and the flux flowing between the semiconductor and the substrate is negligibly small.

Lateral high-voltage semiconductor devices with surface covered by thin film of dielectric material with high permittivity

A semiconductor high-voltage device comprising a voltage sustaining layer between a n -region and a p -region is provided, which is a uniformly doped n(or p)-layer containing a plurality of floating p(or n)-islands. The effect of the floating islands is to absorb a large part of the electric flux when the layer is fully depleted under a high reverse bias voltage so as the peak field is not increased when the doping concentration of voltage sustaining layer is increased. Therefore, the thickness and the specific on-resistance of the voltage sustaining layer for a given breakdown voltage can be much lower than those of a conventional voltage sustaining layer with the same breakdown voltage. By using the voltage sustaining layer of this invention, various high voltage devices can be made with better relation between specific on-resistance and breakdown voltage.

Growing community of inventors

Chengdu, China

Xingbi Chen