Trench field stop type IGBT (Insulated Gate Bipolar Translator)

Abstract

The invention discloses a trench field stop type IGBT (Insulated Gate Bipolar Transistor), which is characterized in that an N-type buffer region is inserted to reduce the occupied thickness of an N-type drift region, a trench gate is additionally arranged to eliminate the influence of an N-type JFET (Junction Field Effect Transistor) in an original device, and compared with the existing device, the trench field stop type IGBT has the optimization effect of reducing voltage drop while reducing the thickness size of the N-type drift region.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a trench field stop IGBT. Background Art

[0002] Among the many power semiconductor devices, IGBT has attracted much attention as a power semiconductor device suitable for high voltage and high current among the currently developed power devices. This is because IGBT has the characteristics of a combination of MOSFET with excellent switching characteristics and BJT with high current driving capability, low forward voltage drop and excellent forward conduction characteristics.

[0003] In order to reduce the power consumption of the system, the technical development direction of IGBT is to maintain a high breakdown voltage and reduce the steady-state power consumption without reducing the switching characteristics. However, with the use of IGBT in high voltage areas, in order to meet the high voltage drop characteristics, the only way is to reduce the dose concentration of the N-type drift area, increase the thickness and voltage drop, and this design structure cannot bring better use results. Summary of the invention

[0004] The purpose of the present invention is to provide a trench field stop IGBT in view of the technical problems existing in the background technology.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A trench field stop IGBT comprises an emitter, an N-type drift region, a trench gate, an N+ drain, a P+ base region, an N-type buffer region, a P+ collector and a collector, wherein the emitter, the N-type drift region, the N-type buffer region, the P+ collector and the collector are stacked in sequence, the P+ base region is arranged on one side of the N-type drift region and is bonded to the emitter, the trench gate is arranged on the other side of the N-type drift region and is bonded to the emitter, the N+ drain is wrapped in the P+ base region, and the adjacent two sides of the N+ drain are respectively bonded to the emitter and the trench gate.

[0007] Preferably, an outer wall of the trench gate is covered with an oxide gate, and one side of the oxide gate extends to the emitter.

[0008] Preferably, the cell pitch of the trench field stop type IGBT is 15 μm, and the threshold voltage of the trench field stop type IGBT is 5.0V.

[0009] Preferably, the thickness of the N-type drift region is 110 μm, and the resistivity of the N-type drift region is 60 Ωcm.

[0010] Preferably, the thickness and width of the trench gate are 3 μm and 10 μm respectively.

[0011] Preferably, the thickness of the N-type buffer region is 0.5 μm, and the resistivity of the N-type buffer region is 0.03 Ωcm.

[0012] Preferably, the dose of the P+ base region is 8.0e13cm -2 , the thickness of the P+ base region is 2.5μm.

[0013] Preferably, the dose of the P+ collector is 1.0e15cm -2 , the thickness of the P+ collector is 0.5μm.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: an N-type buffer zone is inserted to reduce the occupied thickness of the N-type drift region, and a trench gate is added to eliminate the influence of the N-type JFET in the original device. Compared with the existing device, while reducing the thickness of the N-type drift region, it also has the optimization effect of reducing the voltage drop. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of the maximum extension length of the depletion layer of a planar non-punch-through IGBT when a breakdown voltage occurs in an embodiment of the present invention;

[0017] Figure 3 A diagram showing the relationship between the threshold voltage of the N-type JFET dose and the P-base dose in the planar non-punch-through IGBT in the embodiment of the present invention;

[0018] Figure 4 A voltage drop relationship diagram according to N-type JFET dosage in a planar non-punch-through IGBT according to an embodiment of the present invention;

[0019] Figure 5 A diagram showing the relationship between the breakdown voltage of a planar non-punch-through IGBT according to the dosage of an N-type JFET in an embodiment of the present invention;

[0020] Figure 6 Graph showing the relationship between the thickness of the N-type drift region and the voltage drop in the planar field stop IGBT in the embodiment of the present invention;

[0021] Figure 7 A schematic diagram of breakdown voltage when a planar non-punch-through IGBT and four planar stop-type IGBTs have N-type drift regions of different thicknesses in an embodiment of the present invention;

[0022] Figure 8 A diagram showing the relationship between the thickness of the N-type buffer region and the electric field distribution (the thickness of the N-type drift region is 110 μm as a quantitative value) in a planar field stop IGBT according to an embodiment of the present invention;

[0023] Fig. 9 A relationship diagram between the thickness of the N-type buffer region and the voltage drop (the thickness of the N-type drift region is 110 μm as a quantitative value) in a planar field stop IGBT in an embodiment of the present invention;

[0024] Fig.10 is a relationship diagram of the thickness of the N-type buffer region, the dose concentration and the breakdown voltage (the thickness of the N-type drift region is 110 μm as a quantitative value) in a planar field stop IGBT in an embodiment of the present invention;

[0025] Fig.11 A relationship diagram between the dose concentration and the voltage drop according to the thickness of the N-type buffer region in the planar field stop IGBT according to an embodiment of the present invention (the thickness of the N-type drift region is 110 μm as a quantitative value);

[0026] Fig.12 is a relationship diagram between the dose concentration of the P+ collector and the voltage drop (the thickness of the N-type drift region is 110 μm as a quantitative value) in the planar field stop IGBT in the embodiment of the present invention;

[0027] Fig.13 The electric field distribution diagram of the planar field stop type IGBT and the planar non-punch-through type IGBT in the embodiment of the present invention;

[0028] Fig.14 A diagram showing the relationship between the breakdown voltage and the voltage drop of the trench gate at different thicknesses and widths in an embodiment of the present invention;

[0029] Fig.15 1 is a performance comparison diagram of the present invention with a planar non-punch-through IGBT and a planar field stop IGBT in an embodiment of the present invention.

[0030] Reference numerals: 100 emitter, 200 N-type drift region, 300 trench gate, 400 N+ drain, 500 P+ base region, 600 N-type buffer region, 700 P+ collector, 800 collector, 900 oxide gate. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0032] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or a specific connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0034] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] like Figure 1-Figure 15 As shown, the present invention provides a trench field stop IGBT, including an emitter 100, an N-type drift region 200, a trench gate 300, an N+ drain 400, a P+ base region 500, an N-type buffer region 600, a P+ collector 700 and a collector 800;

[0036] The emitter 100, the N-type drift region 200, the N-type buffer region 600, the P+ collector 700 and the collector 800 are stacked in sequence, the P+ base region 500 is arranged on one side of the N-type drift region 200 and adheres to the emitter 100, the trench gate 300 is arranged on the other side of the N-type drift region 200 and adheres to the emitter 100, the N+ drain 400 is wrapped in the P+ base region 500, and the adjacent two sides of the N+ drain 400 are respectively adhered to the emitter 100 and the trench gate 300.

[0037] Furthermore, the outer wall of the trench gate 300 is covered with an oxide gate 900 , and one side of the oxide gate 900 extends to the emitter 100 .

[0038] Specific design and simulation analysis, in this embodiment, two structures are used as an improved control group of the trench field stop type IGBT, specifically a planar non-punch-through IGBT and a planar field stop type IGBT.

[0039] First, the trench field stop IGBT, the planar non-punch-through IGBT and the planar field stop IGBT all adopt the 1200V level, and the cell pitch of the trench field stop IGBT is 15μm.

[0040] Table 1 is as follows:

[0041]

[0042] Table 2 is as follows:

[0043] Breakdown voltage(V)

[0044]

[0045] The planar non-punch-through IGBT is designed using the process conditions in Table 1. From Table 2, it can be seen that if the thickness of the drift region exceeds 200μm, the increase will be significantly reduced. Figure 2 It can be seen that the maximum length of the depletion layer is 157μm. If the thickness of the drift region is less than this length, source-drain punch-through will occur. As the drift region increases, the on-resistance tends to increase, which is a trade-off relationship. Therefore, in order to achieve the target voltage reduction and avoid source-drain punch-through, the drift region should be set to 180μm. At the same time, it is necessary to confirm that the field-stop IGBT designed in the future requires an N-type drift region 200 thick below 157μm to be formed.

[0046] In order to further optimize the planar non-punch-through IGBT, the wafer resistivity is set to 60Ωcm, the drift region is set to 180μm, and the dose of the N-type JFET and P-type base region is adjusted to k11~4e11cm -2 and 5e13~~8e13cm -2 , and conduct simulation, as shown in the attached Figure 3-4 , so the dose of the P-type base region is selected to be 6.5e13cm -2 , the dose for N-type JFET is 1e12cm -2 , the threshold voltage is 5.5V, the voltage drop is 2.35V (based on 100A standard), and the breakdown voltage is 1425V. When the yield phenomenon occurs, the length of the remaining drift region is about 23μm.

[0047] Table 3 (the final process of planar non-punch-through IGBT) is as follows:

[0048]

[0049] A planar field stop type IGBT is designed based on the design of a planar non-punch-through type IGBT, into which an N-type buffer region 600 with a thickness of 2.5 μm is inserted. The thickness of the N-type buffer region 600, the thickness of the N-type drift region 200 and the dose concentration of the N-type drift region 200 are simulated based on the process in Table 4.

[0050] Table 4 is as follows:

[0051]

[0052] See attached Figure 6-7 , observing the increase in breakdown voltage caused by the insertion of the N-type buffer 600, the drift region thickness must be less than 157μm. Under the N-type buffer 600 concentration and thickness assumed above and in Table 4, the smaller the thickness of the N-type drift region 200, the lower the breakdown voltage will be. In addition, the voltage drop is also reduced. In order to achieve the design target value, the thickness of the N-type drift region 200 is determined to be 110um.

[0053] See attached Figure 8-9 According to the thickness of the N-type buffer layer 600, it can be confirmed that the breakdown voltage is almost unchanged, but as the thickness of the N-type buffer layer 600 decreases, the voltage drop decreases significantly. Figure 10-11 It can be seen that when the thickness of the N-type buffer layer 600 is 0.5 μm, the design target value is met.

[0054] Table 5 is as follows:

[0055] On state Voltage drop(V) / Breakdown Voltage(V)

[0056]

[0057] Based on the process in Table 5, and Fig.12 The simulation results confirm that the dose of P+ collector 700 is 1.0e15cm -2 .

[0058] Table 6 is as follows:

[0059] On state Voltage drop(V) / Breakdown voltage(V)

[0060]

[0061] From the results shown in Table 6, it can be seen that when the thickness of the N-type drift region 200 is 110 μm, the thickness of the N-type buffer region 600 is 0.5 μm, the resistivity of the N-type buffer region 600 is 0.03 Ωcm, and the dosage of the P+ collector 700 is 1.0e15 cm -2 When , a breakdown voltage of 1458V and a voltage drop of 1.55V are obtained.

[0062] Table 7 is as follows:

[0063]

[0064] Based on the process of Table 7, a trench field stop type IGBT is designed by inserting a trench gate 300 on the basis of the above-mentioned planar field stop type IGBT. The threshold voltage of the trench field stop type IGBT is 5.0V, and the corresponding dose of the P+ base region 500 is 8.0e13cm -2 Since the depth and width of the trench gate 300 are not calibrated, the trench gate 300 in the trench field stop type IGBT is simulated to obtain a data table as shown in Table 8.

[0065] Table 8 is as follows:

[0066] On state Voltage drop(V) / Breakdown voltage(V)

[0067]

[0068] It can be seen from Table 8 that the breakdown voltage is positively correlated only with the depth change of the trench gate 300. Due to the electric field concentration at the bottom of the trench gate 300, the depletion layer expands and prevents the current from flowing. In addition, the breakdown voltage is almost unaffected by the width of the trench gate 300. The deeper the trench gate 300, the smaller the breakdown voltage. This is due to the electric concentration phenomenon at the bottom of the trench gate 300.

[0069] Table 9 is as follows:

[0070]

[0071] Based on the above Table 9 and the attached Fig.13 The designed trench field stop IGBT has an N-type drift region 200 with a thickness of 100 μm, an N-type buffer region 600 with a thickness of 0.5 μm, and a resistivity of 0.03 Ωcm, which has good performance compared to a planar non-punch-through IGBT.

[0072] Table 10 is as follows:

[0073]

[0074] Finally, see Table 10 and Appendix Figure 14-15 , it can be seen that the breakdown voltage is positively correlated with the thickness of the trench gate, and it is confirmed that the thickness and width of the trench gate 300 are 3μm and 10μm respectively, the thickness of the P+ base region 500 is 2.5μm, and the dose of the P+ collector 700 is 1.0e15cm -2 , the thickness of the P+ collector 700 is 0.5 μm.

[0075] Therefore, by inserting the N-type buffer layer 600, the thickness of the N-type drift region 600 can be reduced. When the breakdown voltage is the same, the voltage drop of the planar field stop type IGBT is reduced by about 35% compared with the voltage drop of the planar non-punch-through type IGBT. To further reduce the voltage drop, the trench gate 300 is inserted again to eliminate the influence of the N-type JFET, which further reduces the voltage drop by about 9%. That is, the voltage drop of the trench field stop type IGBT designed in the end is reduced by about 44% compared with the voltage drop of the planar non-punch-through type IGBT.

[0076] The above is a trench field stop IGBT or multiple implementations provided in combination with specific content, and the specific implementation of the present invention is not limited to these descriptions. Any similarity or similarity with the method, structure, etc. of the present invention, or a number of technical deductions or replacements based on the concept of the present invention, should be regarded as the protection scope of the present invention.

Claims

1. A trench field stop IGBT, characterized in that: include: An emitter (100), an N-type drift region (200), a trench gate (300), an N+ drain (400), a P+ base region (500), an N-type buffer region (600), a P+ collector (700), and a collector (800); The emitter (100), the N-type drift region (200), the N-type buffer region (600), the P+ collector (700) and the collector (800) are stacked in sequence; the P+ base region (500) is arranged on one side of the N-type drift region (200) and is bonded to the emitter (100); the trench gate (300) is arranged on the other side of the N-type drift region (200) and is bonded to the emitter (100); the N+ drain (400) is wrapped in the P+ base region (500); and the adjacent two sides of the N+ drain (400) are respectively bonded to the emitter (100) and the trench gate (300).

2. A trench field stop type IGBT according to claim 1, characterized in that: The outer wall of the trench gate (300) is covered with an oxide gate (900), and one side of the oxide gate (900) extends to the emitter (100).

3. The trench field stop IGBT according to claim 1, characterized in that: The cell pitch of the trench field stop type IGBT is 15 μm, and the threshold voltage of the trench field stop type IGBT is 5.0V.

4. A trench field stop type IGBT according to claim 3, characterized in that: The thickness of the N-type drift region (200) is 110 μm, and the resistivity of the N-type drift region (200) is 60 Ωcm.

5. The trench field stop type IGBT according to claim 4, characterized in that: The thickness and width of the trench gate (300) are 3 μm and 10 μm respectively.

6. The trench field stop IGBT according to claim 4, characterized in that: The thickness of the N-type buffer region (600) is 0.5 μm, and the resistivity of the N-type buffer region (600) is 0.03 Ωcm.

7. The trench field stop type IGBT according to claim 4, characterized in that: The dose of the P+ base region (500) is 80e13cm -2 , the thickness of the P+ base region (500) is 2.5 μm.

8. The trench field stop type IGBT according to claim 4, characterized in that: The dosage of the P+ collector (700) is 1.0e15cm -2 , the thickness of the P+ collector (700) is 0.5 μm.

Images