阅读说明：本技术 一种逆导型mos触发晶闸管及其制造方法 (Reverse conducting MOS (Metal oxide semiconductor) triggered thyristor and manufacturing method thereof ) 是由 陈万军 袁榕蔚 朱建泽 刘超 于 2021-01-11 设计创作，主要内容包括：本发明涉及半导体技术,特别涉及一种逆导型MOS触发晶闸管及其制造方法。本发明的MOS部分为PNPN晶闸管提供驱动电流,在几十纳秒内快速触发整个器件开启,这样器件获得大电流能力。本发明的结构中阳极部分具有由N型阳极、P型阳极和阳极金属构成的,为器件提供逆导能力。本发明提供了一种应用于脉冲功率领域的大电流驱动器件。相比于传统的MCT而言,本发明的RC-MCT可以使用在脉冲功率电路中,可以不使用并联二极管,起到续流作用,这样的优点是系统复杂度降低,降低成本,节省脉冲电路。(The invention relates to a semiconductor technology, in particular to a reverse conducting MOS (metal oxide semiconductor) triggered thyristor and a manufacturing method thereof. The MOS part of the invention provides driving current for the PNPN thyristor, and the whole device is rapidly triggered to be started within dozens of nanoseconds, so that the device obtains large current capability. The anode part in the structure of the invention is composed of an N-type anode, a P-type anode and anode metal, and provides reverse conductivity for the device. The invention provides a high-current driving device applied to the field of pulse power. Compared with the traditional MCT, the RC-MCT can be used in a pulse power circuit, and can play a role of freewheeling without using a parallel diode, so that the advantages of reducing system complexity, reducing cost and saving a pulse circuit are achieved.)

1. A reverse conducting MOS triggering thyristor comprises a cellular junction, a negative electrode structure and a negative electrode structure, wherein the cellular junction comprises an anode structure, a drift region structure positioned on the upper surface of the anode structure, and a gate structure and a negative electrode structure positioned on the upper surface of the drift region; the drift region structure is an N-drift region (4), the grid structure comprises a grid oxide layer (8) and a grid electrode (9), and the grid oxide layer (8) is positioned at one end of the upper surface of the N-drift region (4); the cathode structure is cathode metal (10), and the cathode metal (10) is positioned at the other end of the upper surface of the N-drift region (4); the silicon-based drift region is characterized in that a P well region (5) is arranged on the upper layer of the N-drift region (4), an N well region (6) is arranged on the upper layer of the P well region (5), a P deep well region (7) is arranged on the upper layer of the N well region (6), and two ends of the upper surfaces of the P deep well region (7), the N well region (6) and the P well region (5) are respectively contacted with the bottoms of a silicon dioxide insulating layer (8) and a cathode metal (10); the positive pole structure includes positive pole metal (1), N type anode region (2) and P type anode region (3), the upper surface of P type anode region (3) contacts with the bottom in N-drift district (4), and N type anode region (2) embedding sets up the one end in P type anode region (3) bottom, and N type anode region (2) are located grid structure below, the lower surface of N type anode region (2) and the lower surface and the positive pole metal (1) upper surface contact of P type anode region (3) other end.

2. A manufacturing method of a reverse conducting MOS triggering thyristor is characterized by comprising the following steps:

the first step is as follows: growing on a silicon wafer substrate to form an N-drift region (4);

the second step is that: forming a gate oxide layer (8) on one end of the upper surface of the N-drift region (4) through thermal oxidation;

the third step: injecting P-type impurities into the other end of the upper layer of the N-drift region (4) and pushing the P-type impurities to form a P well region (5) by utilizing an ion injection and high-temperature junction pushing process, wherein the upper surface of one end of the P well region (5) is contacted with the bottom of the gate oxide layer (8);

the fourth step: injecting N-type impurities into the upper layer of the P well region (5) to form an N well region (6) by utilizing ion injection and high-temperature junction pushing processes, wherein the upper surface of one end of the N well region (6) is contacted with the bottom of the gate oxide layer (8);

the fifth step: injecting P-type impurities into the upper layer of the N-well region (6) to form a P-type deep well region (7) by utilizing ion injection and high-temperature junction pushing processes, wherein the upper surface of one end of the P-type deep well region (7) is contacted with the bottom of the gate oxide layer (8);

and a sixth step: depositing a layer of polysilicon/metal on the gate oxide layer (8) and forming a gate electrode (9) by etching;

the seventh step: depositing a BPSG insulating medium layer on the upper surface of the device, and etching an ohmic contact hole;

eighth step: depositing metal on the other end of the upper surface of the N-drift region (4) to form cathode metal (10); the bottom of the cathode metal (10) is contacted with the upper surfaces of the other ends of the P well region (5), the N well region (6) and the P deep well region (7);

the ninth step: depositing a passivation layer on the surface of the device;

the tenth step: thinning and polishing the lower surface of the N-drift region (4), injecting P-type impurities and performing ion activation to form a P-type anode region (3); injecting N-type impurities into one end of the lower layer of the P-type anode region (3) and activating ions to form an N-type anode region (2), wherein the N-type anode region (2) is positioned below the grid;

the eleventh step: and back gold, and forming anode metal (1) at the bottoms of the P-type anode region (3) and the N-type anode region (2).

Technical Field

The present invention relates to semiconductor technology, and more particularly, to a Reverse Conducting MOS-triggered Thyristor (RC-MCT) and a method for manufacturing the same.

Background

The power semiconductor device is used as a switching device and can be applied to the fields of power electronics and power pulse. The traditional Thyristor (Thyristor) has the advantages of low conduction voltage drop, large voltage capacity, large current density and the like, and is very suitable for being applied to the field of power pulse. Since the advent of thyristors, their related products have gained wide application in the fields of power pulsing and the like. However, the thyristor drive is current controlled, which increases the complexity of the system, reduces the reliability, and is also not conducive to miniaturization of the pulse power system.

An Insulated Gate Bipolar Transistor (IGBT) is a device widely applied to the field of power electronics, and is a voltage control type device with simple structure and mature and reliable manufacturing process. However, IGBTs have current saturation capability, which limits their application to high power densities. An MOS Controlled Thyristor (MCT for short) is a semiconductor device with the advantages of both power MOS and Thyristor, has the advantages of voltage control drive, no current saturation and high power density, and is very suitable for being applied to the high-power field. Compared with the traditional MCT, the RC-MCT can be used in a pulse power circuit, a freewheeling diode does not need to be connected in parallel, and a reverse current leakage channel exists in the device, so that the advantages of realizing a reverse conductance function, reducing the complexity of a pulse circuit, facilitating circuit integration and reducing the cost are achieved on the basis of not increasing the unit cell width.

Disclosure of Invention

The invention provides a reverse conducting MOS control thyristor which is applied to the field of high voltage and high power and has the characteristic of simple driving.

The technical scheme of the invention is as follows: a reverse conducting MOS controlled thyristor is disclosed, as shown in FIG. 1, the cellular junction of which comprises an anode structure, a drift region structure located on the upper surface of the anode structure, a gate structure located on the upper surface of the drift region and a cathode structure; the drift region structure is an N-drift region 4, the grid structure comprises a grid oxide layer 8 and a grid electrode 9, and the grid oxide layer 8 is positioned at one end of the upper surface of the N-drift region 4; the cathode structure is cathode metal 10, and the cathode metal 10 is positioned at the other end of the upper surface of the N-drift region 4; the drift region is characterized in that a P well region 5 is arranged on the upper layer of the N-drift region 4, an N well region 6 is arranged on the upper layer of the P well region 5, a P deep well region 7 is arranged on the upper layer of the N well region 6, and two ends of the upper surfaces of the P deep well region 7, the N well region 6 and the P well region 5 are respectively contacted with the bottoms of a silicon dioxide insulating layer 8 and a cathode metal 10; the positive pole structure includes positive pole metal 1, N type positive pole district 2 and P type positive pole district 3, the upper surface in P type positive pole district 3 contacts with the bottom of N-drift region 4, and N type positive pole district 2 imbeds and sets up the one end in P type positive pole district 3 bottoms, and N type positive pole district 2 is located grid structure below, and the lower surface in N type positive pole district 2 and the lower surface and the 1 upper surface contact of positive pole metal of the 3 other ends in P type positive pole district.

According to the main scheme of the invention, the reverse conducting structure is that an N-type anode region 2 wraps the inside of a P-type semiconductor anode region 3 and is arranged above an anode metal 1; the introduction of the reverse conducting structure enables the device to have the reverse conducting capability; the N-type anode region 2 can adjust the concentration and the length according to actual needs, and the P-type anode region 3 can change the implantation dosage and the quantity according to the actual needs.

The MOS part of the reverse-conducting MCT provided by the invention can be arranged into a groove type gate or a plane type gate.

A manufacturing method of a reverse conducting MOS triggering thyristor comprises the following steps:

the first step is as follows: growing on a silicon wafer substrate to form an N-drift region 4; as shown in fig. 2;

the second step is that: forming a gate oxide layer 8 on one end of the upper surface of the N-drift region 4 through thermal oxidation; as shown in fig. 3;

the third step: injecting P-type impurities into the other end of the upper layer of the N-drift region 4 and pushing the P-type impurities to form a P well region 5 by utilizing an ion injection and high-temperature junction pushing process, wherein the upper surface of one end of the P well region 5 is contacted with the bottom of the gate oxide layer 8; as shown in fig. 4;

the fourth step: injecting N-type impurities into the upper layer of the P well region 5 by utilizing an ion injection and high-temperature junction pushing process to form an N well region 6, wherein the upper surface of one end of the N well region 6 is contacted with the bottom of the gate oxide layer 8; as shown in fig. 5;

the fifth step: injecting P-type impurities into the upper layer of the N-well region 6 by using ion injection and high-temperature junction pushing processes to form a P-type deep well region 7, wherein the upper surface of one end of the P-type deep well region 7 is in contact with the bottom of the gate oxide layer 8; as shown in fig. 6;

and a sixth step: depositing a layer of polysilicon/metal on the gate oxide layer 8 and then forming a gate electrode 9 by etching; as shown in fig. 7;

the seventh step: depositing a BPSG insulating medium layer on the upper surface of the device, and etching an ohmic contact hole;

eighth step: depositing metal on the other end of the upper surface of the N-drift region 4 to form cathode metal 10; the bottom of the cathode metal 10 is contacted with the upper surfaces of the other ends of the P well region 5, the N well region 6 and the P deep well region 7; as shown in fig. 8;

the ninth step: depositing a passivation layer on the surface of the device;

the tenth step: thinning and polishing the lower surface of the N-drift region 4, injecting P-type impurities and performing ion activation to form a P-type anode region 3; injecting N-type impurities into one end of the lower layer of the P-type anode region 3 and carrying out ion activation to form an N-type anode region 2, wherein the N-type anode region 2 is positioned below the grid; as shown in fig. 9;

the eleventh step: back gold, forming anode metal 1 at the bottom of the P-type anode region 3 and the N-type anode region 2, as shown in fig. 10; .

Among the above manufacturing methods, the method of manufacturing the N-type anode region 2 is: the mask plate adopted when the N-type anode region 2 is formed by injecting N-type impurities into the P-type anode region 3 has a shielding region, and the part of the P-type anode region 3 shielded by the shielding region is not injected by the N-type impurities. And the formed N-type anode region 2 is in a short circuit structure with the P-type base region 3 connected with the anode metal 1.

Compared with the traditional MCT, the RC-MCT has the advantages that the RC-MCT can be used in a pulse power circuit, a parallel diode is not used, and a follow current effect is achieved, so that the system complexity is reduced, the cost is reduced, and a pulse circuit is saved.

Drawings

FIG. 1 is a schematic diagram of a planar gate cell structure of a reverse conducting MOS-triggered thyristor according to the present invention;

FIG. 2 is a schematic structural diagram of the present invention after the fabrication of the N-drift region;

FIG. 3 is a schematic diagram of a structure after forming a gate oxide in the fabrication process flow of the present invention;

FIG. 4 is a schematic structural diagram of a P-type semiconductor base region formed by injecting P-type impurity into a plug junction in the manufacturing process flow of the present invention;

FIG. 5 is a schematic structural diagram of an N-type semiconductor source region formed by ion implantation of N-type impurity push-junction in the fabrication process flow of the present invention;

FIG. 6 is a schematic structural diagram of a P-type semiconductor drain region formed by ion implantation of P-type impurity push-junction in the fabrication process flow of the present invention;

FIG. 7 is a schematic structural diagram of a gate electrode formed by depositing a polysilicon/metal layer on a gate oxide layer and etching the polysilicon/metal layer in the process flow of the present invention;

FIG. 8 is a schematic view of the front side metallization of the fabrication process flow of the present invention;

FIG. 9 is a schematic structural diagram of an anode region formed by P-type impurity implantation after back thinning in the manufacturing process flow of the present invention;

FIG. 10 is a schematic view of a back side metalized structure in a process flow of the present invention;

FIG. 11 is a schematic diagram of a trench gate cell structure of the reverse conducting MOS-triggered thyristor according to the present invention;

FIG. 12 is a reverse conducting schematic diagram of a reverse conducting MOS-triggered thyristor according to the present invention;

FIG. 13 is a reverse conducting schematic diagram of a reverse conducting MOS-triggered thyristor according to the present invention;

FIG. 14 is a schematic diagram of the blocking characteristic of the reverse conducting MOS-triggered thyristor according to the present invention;

FIG. 15 is a schematic diagram of a pulsing circuit of the present invention;

fig. 16 is a schematic diagram of a pulse discharge characteristic of the present invention.

Detailed Description

The invention is described in detail below with reference to the attached drawing

The MOS-triggered thyristor planar grid type cellular structure provided by the invention is shown in figure 1, the MOS part of the MOS-triggered thyristor provides driving current for a PNPN thyristor, and the whole device is rapidly triggered to be started within tens of nanoseconds, so that the device obtains large-current capability. The anode part is composed of an N-type anode region 2, a P-type anode region 3 and anode metal 1 and provides reverse conductivity for the device.

The MOS part of the reverse-conducting MCT provided by the invention can be arranged into a groove-type gate and a plane-type gate, the structure of the groove-gate type MCT unit cell is shown in figure 11, and the structure of the plane-gate type MTD unit cell is shown in figure 1.

The operating principle of the reverse conducting MCT provided by the invention is as follows:

in the cell structure shown in fig. 13, a positive voltage is first applied to the polysilicon gate 9, and the P channel is inverted. When a positive voltage is applied to the anode 10 and the cathode 1 is connected with a zero potential, the N-type base electrode 6 injects electrons into the N-drift region 4, so that PNP formed by the P-type anode region 3, the N-drift region 4 and the P-type source region 5 is started, and holes are injected into the P-type source region 5, so that NPN formed by the N-drift region 4, the P-type base region 5 and the N-type base region 6 is started; this injects electrons into the N-type drift region again, forms the positive feedback, thus make the thyristor turn on; forming a forward current from the anode to the cathode, which charges the barrier capacitance C1 by the P-type anode region 3 and the N-drift region 4; so that the P-type side accumulates positive charges and the N-type side accumulates negative charges.

When the anode 10 changes from positive voltage to negative voltage, the cathode 1 is connected with zero potential; the barrier capacitor C1 begins to discharge, and the positive charges on the P-type side will discharge from the boundary of P-anode/N-drift, forming a current, as shown in fig. 14; this causes the P-anode/N-anode junction to turn on, thus the NPN formed by N-anode, P-anode and N-drift and the PNP formed by P-anode, N-drift and P-well to turn on; and the reverse thyristor is started to realize the reverse conducting function.

As shown in fig. 12, the relationship between the cathode current and the cathode voltage when the CS-MCT is turned on reversely can be adjusted by adjusting the doping concentration of the P-type anode region and the length of the N-type anode region in fig. 1. Reducing the doping concentration of the P-type anode region and increasing the length of the N-type anode can increase the resistance of a path through which current flows when the P-type anode and the N-type anode are reversely conducted, so that the voltage of the P-type anode and the voltage of the N-type anode reach the starting voltage as soon as possible, the reverse current can smoothly flow to the anode, the latch-up voltage is reduced, and the device is reversely conducted.

The invention can be widely applied in the aspect of pulse, as shown in fig. 16, in the pulse circuit in fig. 15, the conventional CS-MCT needs a reverse parallel free-wheeling diode in the pulse circuit, because the conventional CS-MCT has no reverse current bleeding path and needs the free-wheeling diode to bleed reverse current; unlike conventional CS-MCT, the present invention can bleed off reverse current due to the presence of the reverse conductance function. Therefore, the invention has the advantages of reducing the complexity of the pulse circuit, facilitating the circuit integration and reducing the cost.

The simulation result of fig. 15 is shown in fig. 16, and it can be seen that the structure is in an underdamped state because the on-resistance is small and the presence of the reverse conducting structure does not improve the on-resistance of the present invention. The blocking voltage of the structure is 3300V, and the blocking voltage cannot be influenced by adjusting the doping concentration of the P-type anode region and increasing the length of the N-type anode; when the voltage of the charging capacitor is 1200V, the peak current 3560A and the pulse width are 590ns, and meanwhile, the anode peak current and the pulse width cannot be influenced by adjusting the doping concentration of the P-type anode region and increasing the length of the N-type anode.

In summary, the RC-MCT of the present invention can be used in a pulse power circuit, without a freewheeling diode connected in parallel, and a reverse current leakage channel exists inside the device, and the structure does not affect the original blocking voltage and the peak current and pulse width in pulse application, and has the advantages of realizing a reverse conductance function, reducing the complexity of the pulse circuit, facilitating circuit integration, and reducing cost, etc. on the basis of not increasing the cell width.