阅读说明：本技术 一种rc-igbt半导体装置 (RC-IGBT semiconductor device ) 是由 不公告发明人 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种RC-IGBT半导体装置,在一个衬底上形成有IGBT和FWD,IGBT具有p型基极层和n型漂移层和多个沟槽栅极结构,栅电极穿过p型基极层,p型基极层由栅电极分成多个间隔区域；在间隔区域中,p型基极层上表面设置有p+发射极区和n+发射极区,n+发射极及p型基极层的侧壁均与沟槽侧壁外表面相接触；FWD设置有形成在n型漂移层表面的多个虚拟沟道,以及在衬底上形成的n型漂移层；在n型漂移层上平行虚拟沟道方向设置有多段p型基区,所述p型基区将位于虚拟沟道之间的n型漂移层隔离出n-漂移区,所述n-漂移区上覆盖有肖特基势垒区。本发明实现低寄生电容,获得低集电极发射极饱和压降VCE(sat)和大短路电流安全工作区。(The invention discloses an RC-IGBT semiconductor device, wherein an IGBT and an FWD are formed on a substrate, the IGBT is provided with a p-type base layer, an n-type drift layer and a plurality of trench gate structures, a gate electrode penetrates through the p-type base layer, and the p-type base layer is divided into a plurality of interval regions by the gate electrode; in the spacing region, a p + emitter region and an n + emitter region are arranged on the upper surface of the p-type base layer, and the side walls of the n + emitter and the p-type base layer are both contacted with the outer surface of the side wall of the groove; the FWD is provided with a plurality of dummy channels formed on the surface of the n-type drift layer, and an n-type drift layer formed on the substrate; a plurality of sections of p-type base regions are arranged on the n-type drift layer in a direction parallel to the virtual channels, the p-type base regions isolate n-drift regions from the n-type drift layer between the virtual channels, and the n-drift regions are covered with Schottky barrier regions. The invention realizes low parasitic capacitance, and obtains low collector emitter saturation voltage drop VCE (sat) and large short-circuit current safe working area.)

1. An RC-IGBT semiconductor device having an IGBT and an FWD formed on one substrate,

the IGBT has: the p-type base region is formed on the surface of the n-type drift layer;

a plurality of trench gate structures, each of the trench gate structures comprising a trench on the substrate, a conductive film in the trench, and a polysilicon gate electrode and a gate oxide layer of an IGBT element; a SiO2 gate oxide layer is arranged in the groove on the substrate, and polycrystalline silicon is deposited on the SiO2 gate oxide layer;

the gate electrode penetrates through the p-type base region, and the p-type base region is divided into a plurality of interval regions by the gate electrode;

in the spacing area, the upper surface of the p-type base region is provided with a p + emitter region and an N + emitter region, and the p + emitter region and the N + emitter region are independent from each other; the N + emitter region is arranged on two sides of the p + emitter region; an n + emitter region is disposed in a surface portion of the spacer region, sidewalls of the n + emitter and the p-type base region each contact an outer surface of a sidewall of the trench, and the n + emitter region and the p + emitter region each are electrically coupled with the emitter electrode; the gate oxide layer is contacted with the N + emitter region and the side face of the p-type base region;

the bottom of the n-type drift layer is provided with an n-type electric field stopping layer; the back surface of the n-type electric field stop layer is in contact with a p + collector region, and the p + collector region is electrically coupled with a collector electrode;

the FWD has: a plurality of dummy channels formed on the surface of the n-type drift layer and the n-type drift layer formed on the substrate are arranged; a plurality of sections of p-type base regions are arranged on the n-type drift layer in a direction parallel to the virtual channels, the p-type base regions isolate n-drift regions from the n-type drift layer between the virtual channels, and the n-drift regions are covered with Schottky barrier regions;

the dummy channels are connected to the emitter electrodes by being coupled together with each other as signal lines;

the dummy channel interval passes through the p-type base layer, the bottom of the dummy channel reaches the substrate, and a p + anode layer is also arranged on the upper surface of the p-type base layer between the dummy channel of the FWD and the gate electrode of the IGBT;

and an n + collector region formed on a back surface of the n-type drift layer of the FWD portion, the collector region being electrically connected to the collector electrode.

2. An RC-IGBT semiconductor device according to claim 1, characterized in that the n + collector region is separated into segments by a plurality of p + collector regions.

3. An RC-IGBT semiconductor device according to claim 2, characterized in that the width of the n + collector region is smaller than the width of the p + collector region.

4. An RC-IGBT semiconductor device as claimed in claim 2, characterized in that a SiO2 oxidation trench is provided between the n + collector region and the p + collector region on the back side of the n-type drift layer of the FWD part.

5. An RC-IGBT semiconductor device according to claim 1, characterized in that an n-type bank is provided under the p-type base layer of the emitter region and between the gate electrode of the IGBT and the dummy channel of the FWD.

6. An RC-IGBT semiconductor device according to claim 1, wherein the semiconductor material of the RC-IGBT semiconductor device is Si, SiC, GaAs or GaN.

7. An RC-IGBT semiconductor device according to claim 1, characterized in that the n-type drift layer is 110um thick.

Technical Field

The invention belongs to the technical field of semiconductors, and particularly relates to an RC-IGBT semiconductor device.

Background

The IGBT is an abbreviation of an Insulated Gate Bipolar Transistor (IGBT), the IGBT is a device formed by compounding an MOSFET and a Bipolar Transistor, the input electrode of the IGBT is the MOSFET, the output electrode of the IGBT is a PNP Transistor, the IGBT combines the advantages of the MOSFET and the Bipolar Transistor, the IGBT has the advantages of small driving power and high switching speed of the MOSFET, the Bipolar device has the advantages of reduced saturation voltage and large capacity, the frequency characteristic of the IGBT is between the MOSFET and the power Transistor, the IGBT can normally work within the frequency range of dozens of kHz, the IGBT is more and more widely applied in modern power electronic technology, and the IGBT occupies a leading position in high-frequency and medium-power application.

The reverse conducting IGBT (switching converting IGBT) integrates a Free wheeling diode (Free wheeling diode) into one chip, and has the advantages of small size, high power density, low cost, high reliability and the like.

Collector-emitter voltage change rate du in IGBT turn-off process_ceThe/dt passes through the Miller capacitance C_GCFeedback to the gate results in a displacement current i_GC. When the voltage UCE rises slowly, the gate voltage is at the miller plateau, this displacement current initially remains stable and helps to maintain the plateau voltage constant. The amplitude of the displacement current is completely dependent on the feedback capacitance C_GC. This in turn is affected by the oxide layer equivalent capacitance and the current control equivalent junction capacitance inside the IGBT. Current l at turn-off of IGBT_CThe larger, the larger the capacitance C_GCThe larger. This is due to the structure of the space charge region inside the IGBT, which consists of junction capacitance. Thus, the collector current I is turned off_CThe larger the displacement current i is generated_GCThe larger this is, which is easy to understand. This positive feedback may cause oscillations when the semiconductors are connected in parallel. The built-in FWD produces a high spike voltage when the IGBT turns off and an oscillation in voltage when the FWD recovers in the reverse direction.

Disclosure of Invention

The invention aims to solve the technical problem of how to avoid voltage and current oscillation caused by high di/dt and dv/dt in the turn-off stage of an IGBT and provide an RC-IGBT semiconductor device.

The invention has the following beneficial technical effects:

the invention realizes low parasitic capacitance, and obtains low collector emitter saturation voltage drop VCE (sat) and a large short-circuit current safe working area;

the p +/p-anode region and the cathode N +/N-of the FWD part effectively restrain carriers, and the reverse recovery power consumption is greatly reduced. The hole entrance from the back side of the IGBT region suppresses the voltage oscillation under diode reverse recovery conditions, and the N +/N-cathode can reduce the tail current during reverse recovery. Further, by electrically fixing impact ionization at the bottom of the trench and injecting holes from the back surface, the electric field intensity near the surface and the back surface is weakened; the Schottky barrier region is adopted, so that the barrier of the device can be reduced, and meanwhile, excellent high-voltage resistance, high-temperature resistance and surge capacity are kept;

the width of a p + collector of the cathode region part of the FWD is larger than that of an n + collector, the influence of the change of a device from a MOSFET (metal oxide semiconductor field effect transistor) working mode to a bipolar IGBT (insulated gate bipolar transistor) working mode is weakened due to the increase of the width of the p + collector, the device can better enter the IGBT mode, and the on-state voltage of the FWD is smaller than that of a traditional RC-IGBT.

Drawings

FIG. 1 is a schematic structural diagram of a conventional RC-IGBT;

fig. 2 is a schematic structural diagram of an RC-IGBT provided in the embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an RC-IGBT according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a cross section of an AA' line of an RC-IGBT according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a cross section of a BB' line of the RC-IGBT provided by the embodiment of the present invention;

FIG. 6 is a schematic structural diagram of an RC-IGBT according to an embodiment of the present invention;

the labels in the figure are: 1: an emitter electrode; 2: an n + emitter region; 3: a polysilicon gate electrode; 5: an N-type drift layer; 6: an n-type electric field stop layer; 7: a p + collector region; 8: an n + collector region; 9: a p-type base region; 10: a collector electrode; 11: an n-type storage region; 12: a p + emitter region; 13: an n-drift region; 14: an insulating film; 15: a gate oxide layer; 16-schottky barrier region.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

The structure of the traditional RC-IGBT is shown in figure 1, when the voltage VCE of a collector and an emitter is greater than 0, under the condition that a grid electrode is opened, the IGBT in the RC-IGBT enters a conducting state, and an integrated freewheeling diode is cut off; when reverse voltage is applied to the collector, the voltage VCE of the collector and the emitter is less than 0, and when the IGBT is turned off, the inductor in the inductive circuit performs follow current discharge through the follow current diode integrated in the RC-IGBT body, and the follow current diode is conducted in the forward direction. When the collector voltage VCE is less than 0, the integrated diode is conducted, but the area of the N + short-circuit region is smaller, the conductance modulation effect generated in the body of the integrated diode is weaker, and due to the existence of the p + collector region 7, the N-type FS layer and the p + collector region 7 form a PN junction reverse piece, so that the forward conduction voltage drop of the device is increased.

Therefore, the RC-IGBT realizes the function of conducting both forward and reverse directions, saves the manufacturing cost and reduces the volume of the device. However, the conventional RC-IGBT structure has the disadvantages that the switching speed of the IGBT is high, high di/dt is generated when the IGBT is turned off and when the FWD is reversely restored, and due to the wiring inductance around the module, L di/dt, that is, turn-off surge voltage is generated.

In order to solve the technical problems, the invention adopts the following technical scheme: