RC-IGBT device with collector depletion effect

Abstract

The invention relates to an RC-IGBT device with a collector depletion effect, and belongs to the technical field of semiconductors. In order to reduce the turn-off loss of a traditional RC-LIGBT device and eliminate the negative resistance effect during forward conduction, P polycrystalline silicon is introduced to the anode N + side of the device to serve as a planar gate, a P-Buried region is introduced below an anode N + region, a low-doped N-region is arranged between the planar gate and the P-Buried region, when forward conduction is conducted and the voltage is low, the P polycrystalline silicon gate and the P-Buried region exhaust the low-doped N-region, and the P polycrystalline silicon gate and the P-Buried region exhaust the low-doped N-region. Therefore, a high-resistance electron channel is formed, and the negative resistance effect is eliminated. Meanwhile, during turn-off, the anode voltage is high, the depletion region disappears, and a low-resistance electron channel is formed, so that turn-off is accelerated, and turn-off loss is reduced. According to the invention, the negative resistance effect of the traditional RC-IGBT is eliminated, the reverse conduction capability is realized, the compromise relationship between the conduction voltage drop and the turn-off loss of the LIGBT is optimized, and under the condition of the same conduction voltage drop, the turn-off loss of the device structure is respectively reduced by 52% and 19% compared with that of an SSA-LIGBT and that of the traditional LIGBT.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor technology, and relates to an RC-IGBT device with a collector depletion effect. BACKGROUND

[0002] An insulated gate bipolar transistor (IGBT) combines the advantages of MOSFET and power bipolar transistor (BJT), has small driving power, fast switching speed, and strong current capacity, is mainly oriented to a medium-high power and medium-high frequency market, and is widely applied to the fields of industry, automobile electronics, consumer electronics, and the like.

[0003] However, as a bipolar device, the IGBT has a large number of minority carriers in the body when turned on, has the characteristics of low on-resistance and strong current capacity due to the influence of the conductance modulation effect, needs to extract the minority carriers completely when turned off, and thus has slow switching speed. Increasing the injection efficiency of the anode P+ region and reducing the forward on-resistance can cause the increase of the turn-off loss, and the LIGBT has a compromise relationship between the on-resistance and the turn-off loss.

[0004] In addition, the traditional LIGBT does not have the function of reverse conduction, and needs to be connected in parallel with a freewheeling diode in actual application. However, the LIGBT and the freewheeling diode are integrated together as discrete devices, have low integration, on the one hand introduce parasitic parameters to affect the performance of the device, and on the other hand also cause the increase of the cost.

[0005] In order to improve the integration of the device, by introducing a short anode N+ region on the anode side of the LIGBT to form a reverse conducting IGBT (RC-IGBT), on the one hand, the anode N+ region of the RC-LIGBT device can quickly extract electrons when the device is turned off, thereby reducing the turn-off loss; on the other hand, the RC-LIGBT internally integrates a diode, which can realize reverse conduction function. However, this structure also has serious defects. At the initial stage of forward conduction of the RC-LIGBT, the current is small, the number of electrons accumulated in the N-buffer layer is small, the potential of the N-Buffer region is not low enough, the PN junction at the anode P+ / N-Buffer is not turned on, and the electrons are absorbed by the anode N+ region. At this time, it is a unipolar conduction mode, the conduction resistance is large, and the conduction voltage drop is large; with the increase of the number of electrons accumulated in the N-Buffer region, the potential of the N-Buffer region decreases, and when the PN junction at the anode P+ / N-Buffer is turned on, the anode P+ region injects holes into the drift region, and the device changes to a bipolar conduction mode, the conduction resistance becomes small, and the conduction voltage drop becomes small. However, when the device switches from unipolar conduction mode to bipolar conduction mode, the output characteristic curve appears negative resistance phenomenon, that is, snapback effect, which will cause additional loss and affect the performance of the device.

[0006] Therefore, how to optimize the trade-off relationship between the conduction voltage drop and the turn-off loss of the LIGBT and eliminate the snapback effect introduced during forward conduction is the research focus. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a RC-IGBT device with a collector depletion effect, which realizes the reverse conduction function of the IGBT while reducing the turn-off loss and optimizing the trade-off relationship between the conduction voltage drop and the turn-off loss.

[0008] In order to achieve the above purpose, the present application provides the following technical scheme:

[0009] A RC-IGBT device with a collector depletion effect, comprising an anode P+ region 1, a P polysilicon gate 2, a gate oxide layer 3 below the P polysilicon gate, an anode N- region 4, an anode N+ region 5, a P-Buried region 6 located below the anode N+ region, an N-Buffer region 7 located below the anode P+ region, an N drift region 8, an oxide layer 9 below the drift region, a P-type substrate 10, a cathode side N polysilicon gate 11, an oxide layer 12 below the cathode side polysilicon gate, a cathode P+ region 13, a cathode N+ region 14, and a cathode P-Body region 15.

[0010] P poly-silicon gate 2, gate oxide layer 3 under P poly-silicon gate, anode N- area 4, anode N+ area 5, P-Buried area 6 under anode N+ area, wherein P poly-silicon gate 2 is connected to anode voltage, P poly-silicon gate 2, gate oxide layer 3 under P poly-silicon gate, P-Buried area 6 under anode N+ area wrap anode N- area 4, anode N+ area 5, and P-Buried area 6 under anode N+ area play a role of depleting anode N- area 4.

[0011] P poly-silicon gate 2 uses P-type poly-silicon gate as gate material, and P poly-silicon gate 2 is connected to anode voltage. Anode N+ area 5 is located in low-doped anode N- area 4, and low-doped P-Buried area 6 is located under anode N- area 4.

[0012] Further, when anode voltage is low, P poly-silicon gate 2 and P-Buried area 6 can deplete anode N- area 4, form a high-resistance electron channel, and eliminate the negative resistance effect.

[0013] Further, when the device is off, the anode voltage is high, the depletion effect of P poly-silicon gate 2 and P-Buried area 6 on anode N- area 4 is weakened, a low-resistance electron channel is formed, electron extraction during off is accelerated, and off loss is reduced.

[0014] Further, when the cathode voltage is applied, electrons can pass through anode N- area 4 to anode N+ area 5, thereby realizing reverse conduction function.

[0015] Further, by changing the doping concentration of P-Buried area 6 and the distance from anode N+ area 5, the strength of the depletion effect can be changed, thereby changing the forward conduction voltage drop and off loss of the device.

[0016] The beneficial effects of the present application are as follows: based on the traditional RC-IGBT device, the anode N+ area is introduced on the structure of the traditional IGBT device, the P-type poly-silicon gate and the oxide layer are added above the anode N+ area, the low-doped N- area is added outside the N+ area, and the low-doped P-Buried area is added below the N- area; when the device is forward conducting, the anode voltage is low, the P poly-silicon gate and the P-Buried area can interact to deplete the N- area, form a high-resistance electron channel, and eliminate the Snapback effect; when the device is off, the anode voltage is high, the depletion region disappears, a low-resistance electron channel is formed, the anode N+ area can quickly extract electrons, and off loss is reduced, thereby greatly optimizing the compromise between the conduction voltage drop and off loss of the device. When the cathode voltage is applied, electrons can pass through the N- area to the anode N+ area, and the reverse conduction function is realized.

[0017] Additional advantages, objects, and features of the application will be apparent to those skilled in the art upon examination of the following specification. It is intended that the application not be limited by any of the details of the specification. Instead, the true scope of the application is to be determined by the full width of the claims. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to make the objectives, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, in which:

[0019] Figure 1 Structure diagram and plan view of the new structure RC-IGBT device of embodiment 1 of the present application;

[0020] Figure 2 Equivalent circuit diagram of Figure 1

[0021] Figure 3 Forward blocking characteristic diagram of embodiment 1 of the present application compared with traditional IGBT and SSA-LIGBT;

[0022] Figure 4 Voltage-current output characteristic diagram of embodiment 1 of the present application compared with traditional IGBT and SSA-LIGBT in forward and reverse conduction states;

[0023] Figure 5 Space charge distribution diagram of embodiment 1 of the present application when anode voltage VA = 0.4 V;

[0024] Figure 6 Turn-off characteristic comparison diagram of embodiment 1 and traditional LIGBT and SSA-LIGBT;

[0025] Figure 7 Comparison diagram of turn-on voltage drop and turn-off loss compromise of embodiment 1 and traditional LIGBT and SSA-LIGBT;

[0026] Legend: anode P+ region 1, P polysilicon gate 2, gate oxide layer below P polysilicon gate 3, anode N- region 4, anode N+ region 5, P-Buried region below anode N+ region 6, N-Buffer region below anode P+ region 7, N drift region 8, oxide layer below drift region 9, P-type substrate 10, cathode side N polysilicon gate 11, oxide layer below cathode side polysilicon gate 12, cathode P+ region 13, cathode N+ region 14, cathode P-Body region 15. DETAILED DESCRIPTION

[0027] ​Following make the specific concrete example explain the embodiment of the present application, the person skilled in the art can be easily understood from the disclosure of the present application other advantages and efficacy.The present application can also be implemented or applied by another different specific embodiment, the details in the present application can be based on different views and applications, with various modifications or changes without departing from the spirit of the present application.It should be noted that the figures provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the following examples and features in the examples can be combined with each other without conflict.

[0028] Wherein, the drawings are only used for example illustration, the representation is only schematic diagram, and not the physical drawing, and can not be understood as the limitation of the present application; in order to better illustrate the embodiment of the present application, some components of the drawings will be omitted, enlarged or reduced, and not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their description in the drawings can be omitted.

[0029] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if there are terms "upper", "lower", "left", "right", "front", "back" and the like indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and not indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the positional relationship described in the drawings is only used for example illustration, and can not be understood as the limitation of the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific situation.

[0030] Example 1:

[0031] As Figure 1 shown, an improvement is made on the traditional RC-IGBT device, the present embodiment provides an RC-IGBT device with collector depletion effect, including anode P+ region 1, P polysilicon gate 2, gate oxide layer 3 below P polysilicon gate, anode N- region 4, anode N+ region 5, P-Buried region 6 below anode N+ region, N-Buffer region 7 below anode P+ region, N drift region 8, oxide layer 9 below drift region, P type substrate 10, cathode side N polysilicon gate 11, oxide layer 12 below cathode side polysilicon gate, cathode P+ region 13, cathode N+ region 14, cathode P-Body region 15;

[0032] During forward conduction, when the anode voltage is low, the P-polysilicon gate and P-Buried region interact to deplete the N-region, forming a high-resistivity electron channel, thus eliminating the snapback effect. During device turn-off, the anode voltage is high, the depletion region disappears, forming a low-resistivity electron channel. The anode N+ region can quickly extract electrons, reducing turn-off losses, thereby significantly optimizing the trade-off between on-state voltage drop and turn-off losses. Furthermore, when a voltage is applied to the cathode, electrons can reach the anode N+ region through the N-region, achieving reverse conduction.

[0033] Figure 2 The diagram shown is the equivalent circuit diagram of the RC-IGBT device in Example 1, where the IGBT is equivalent to an NMOS-controlled PNP transistor; the anode-biased MOS transistor is connected in parallel to the base and collector of the PNP transistor; the anode N-region forms a variable resistor.

[0034] Figure 3 This is a comparison of the blocking characteristics of Example 1 when the drift region length is 20 mm. Example 1 has a drift region concentration of 2.3 × 10¹⁵ cm⁻¹. -3 The breakdown voltage at that time was 239V.

[0035] Figure 4 Example 1 shows a drift region length of 20 mm and a concentration of 2.3 × 10¹⁵ cm⁻¹. -3 Voltage-current output characteristics under forward and reverse conduction states. At 100A / cm² 2 Example 1 has a forward voltage drop of 1.82V, while the SSA-LIGBT has a forward voltage drop of 2.08V. Example 1 has a lower forward voltage drop and eliminates voltage foldback.

[0036] Figure 5 The diagram shows the space charge distribution of Example 1 at an anode voltage of 0.4 V. The N- region where the anode N+ is located is depleted, which has a blocking effect on electrons, equivalent to a high-resistance electron channel, thus eliminating the negative resistance effect during forward conduction.

[0037] Figure 6 The chart shows a comparison of the turn-off characteristics of Example 1 with those of conventional LIGBT and SSA-LIGBT. The turn-off time of Example 1 is 27ns, which is lower than that of SSA-LIGBT (33ns) and conventional LIGBT (53ns), indicating a faster turn-off speed.

[0038] Figure 7This is a comparison chart showing the trade-off relationship between on-state voltage drop and turn-off loss for Example 1 and conventional LIGBT and SSA-LIGBT. Example 1 reduces turn-off loss by 19% compared to conventional LIGBT when the on-state voltage drop is 1.9V, and reduces turn-off loss by 52% compared to SSA-LIGBT when the on-state voltage drop is 2.15V. In other words, Example 1 has a better trade-off relationship between on-state voltage drop and turn-off loss compared to conventional LIGBT and SSA-LIGBT.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An RC-IGBT device with collector depletion effect, comprising an anode P+ region (1), a P-polysilicon gate (2), a gate oxide layer below the P-polysilicon gate (3), an anode N- region (4), an anode N+ region (5), a P-Buried region below the anode N+ region (6), an N-Buffer region below the anode P+ region (7), an N-Drift region (8), an oxide layer below the drift region (9), a P-type substrate (10), a cathode-side N-polysilicon gate (11), an oxide layer below the cathode-side polysilicon gate (12), a cathode P+ region (13), a cathode N+ region (14), and a cathode P-Body region (15). The P-polysilicon gate (2), the gate oxide layer (3) below the P-polysilicon gate, the anode N- region (4), the anode N+ region (5), and the P-Buried region (6) located below the anode N+ region are on the right side of the anode P+ region. The P-polysilicon gate (2) is connected to the anode voltage. The P-polysilicon gate (2), the gate oxide layer (3) below the P-polysilicon gate, and the P-Buried region (6) located below the anode N+ region enclose the anode N- region (4) and the anode N+ region (5), and play a depletion role on the anode N- region (4).

2. The RC-IGBT device with collector depletion effect according to claim 1, characterized in that, The P-type polysilicon gate (2) uses a P-type polysilicon gate as the gate material and is connected to the anode voltage. The anode N+ region (5) is located within the low-doped anode N- region (4), and the low-doped P-Buried region (6) is located below the anode N- region (4).

3. The RC-IGBT device with collector depletion effect according to claim 1, characterized in that, When the anode voltage is low, the P-polysilicon gate (2) and the P-Buried region (6) can deplete the anode N-region (4) to form a high-resistivity electron channel and eliminate the negative resistance effect.

4. The RC-IGBT device with collector depletion effect according to claim 1, characterized in that, When the device is turned off, the anode voltage is high, and the depletion effect of the P polysilicon gate (2) and the P-Buried region (6) on the anode N-region (4) is weakened, forming a low-resistance electron channel, which accelerates electron extraction during turn-off and reduces turn-off loss.

5. The RC-IGBT device with collector depletion effect according to claim 1, characterized in that, When a voltage is applied to the cathode, electrons will pass through the N- region (4) of the anode and reach the N+ region (5) of the anode, thereby achieving reverse conduction function.

6. The RC-IGBT device with collector depletion effect according to claim 1, characterized in that, The strength of the depletion effect can be changed by altering the doping concentration of the P-Buried region (6) and its distance from the anode N+ region (5), thereby changing the forward conduction voltage drop and turn-off loss of the device.

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