WO2022202041A1 - 半導体装置 - Google Patents
半導体装置 Download PDFInfo
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- WO2022202041A1 WO2022202041A1 PCT/JP2022/007067 JP2022007067W WO2022202041A1 WO 2022202041 A1 WO2022202041 A1 WO 2022202041A1 JP 2022007067 W JP2022007067 W JP 2022007067W WO 2022202041 A1 WO2022202041 A1 WO 2022202041A1
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- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
- H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
- H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
- H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
- H01L29/0619—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
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- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/70—Bipolar devices
- H01L29/72—Transistor-type devices, i.e. able to continuously respond to applied control signals
- H01L29/739—Transistor-type devices, i.e. able to continuously respond to applied control signals controlled by field-effect, e.g. bipolar static induction transistors [BSIT]
- H01L29/7393—Insulated gate bipolar mode transistors, i.e. IGBT; IGT; COMFET
- H01L29/7395—Vertical transistors, e.g. vertical IGBT
- H01L29/7396—Vertical transistors, e.g. vertical IGBT with a non planar surface, e.g. with a non planar gate or with a trench or recess or pillar in the surface of the emitter, base or collector region for improving current density or short circuiting the emitter and base regions
- H01L29/7397—Vertical transistors, e.g. vertical IGBT with a non planar surface, e.g. with a non planar gate or with a trench or recess or pillar in the surface of the emitter, base or collector region for improving current density or short circuiting the emitter and base regions and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
- H01L29/0684—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by the shape, relative sizes or dispositions of the semiconductor regions or junctions between the regions
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- H01L29/0696—Surface layout of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
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- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
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- H01L29/66325—Bipolar junction transistors [BJT] controlled by field-effect, e.g. insulated gate bipolar transistors [IGBT]
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- H01L29/66348—Vertical insulated gate bipolar transistors with a recessed gate
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- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
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- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/402—Field plates
- H01L29/407—Recessed field plates, e.g. trench field plates, buried field plates
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- H—ELECTRICITY
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- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
- H01L29/417—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions carrying the current to be rectified, amplified or switched
Definitions
- the present disclosure relates to semiconductor devices.
- semiconductor devices such as IGBTs (Insulated Gate Bipolar Transistors) are known to have a trench gate structure capable of achieving low on-resistance (see Patent Document 1, for example).
- IGBTs Insulated Gate Bipolar Transistors
- a semiconductor device that solves the above problems includes a drift layer of a first conductivity type, a body region of a second conductivity type formed on the surface side of the drift layer, and a body region that penetrates the body region to reach the drift layer.
- FIG. 1 is a plan view of one embodiment of a semiconductor device.
- FIG. 2 is a cross-sectional view showing an example of the cross-sectional structure of the main cell region of the semiconductor device.
- FIG. 3 is an enlarged view of part of FIG.
- FIG. 4 is a graph showing the relationship between the depth of the drift layer of the semiconductor device and the impurity concentration.
- FIG. 5 is an explanatory diagram for explaining the manufacturing process of one embodiment of the method for manufacturing a semiconductor device.
- FIG. 6 is an explanatory diagram for explaining an example of the manufacturing process of the method for manufacturing a semiconductor device.
- FIG. 7 is an explanatory diagram illustrating an example of a manufacturing process of a method for manufacturing a semiconductor device.
- FIG. 5 is an explanatory diagram for explaining the manufacturing process of one embodiment of the method for manufacturing a semiconductor device.
- FIG. 6 is an explanatory diagram for explaining an example of the manufacturing process of the method for manufacturing a semiconductor device.
- FIG. 7 is an explanatory diagram
- FIG. 8 is an explanatory diagram illustrating an example of a manufacturing process of a method of manufacturing a semiconductor device.
- FIG. 9 is an explanatory diagram for explaining an example of the manufacturing process of the method for manufacturing a semiconductor device.
- FIG. 10 is an explanatory diagram for explaining an example of the manufacturing process of the method for manufacturing a semiconductor device.
- FIG. 11 is an explanatory diagram for explaining an example of the manufacturing process of the method for manufacturing a semiconductor device.
- 12 is a cross-sectional view showing an example of the cross-sectional structure of the main cell region of the semiconductor device of Experimental Example 1.
- FIG. 13 is a cross-sectional view showing an example of the cross-sectional structure of the main cell region of the semiconductor device of Experimental Example 2.
- FIG. 14 is a graph showing the relationship between the depth of the drift layer of the semiconductor device and the electric field intensity.
- FIG. 15 is a graph showing the relationship between collector-emitter saturation voltage and loss when the semiconductor device is turned off.
- FIG. 16 is a graph showing the relationship between collector-emitter saturation voltage and loss when the semiconductor device is turned on.
- FIG. 17 is a graph showing the relationship between the collector-emitter saturation voltage and the total loss when the semiconductor device is driven.
- FIG. 18 is a graph showing changes in collector-emitter voltage, gate-emitter voltage, and collector current when the semiconductor device is turned off.
- FIG. 19 is a cross-sectional view showing an example of cross-sectional structures of a main cell region and a diode cell region of a semiconductor device of a modification.
- FIG. 19 is a cross-sectional view showing an example of cross-sectional structures of a main cell region and a diode cell region of a semiconductor device of a modification.
- FIG. 20 is a cross-sectional view showing an example of cross-sectional structures of a main cell region and a diode cell region of a semiconductor device of a modification.
- FIG. 21 is a cross-sectional view showing an example of cross-sectional structures of a main cell region and a diode cell region of a semiconductor device of a modification.
- FIG. 22 is a cross-sectional view showing an example of cross-sectional structures of a main cell region and a diode cell region of a semiconductor device of a modification.
- FIG. 23 is a cross-sectional view showing an example of the cross-sectional structure of the main cell region and the surrounding region of the semiconductor device of the modification.
- FIG. 24 is a cross-sectional view showing an example of the cross-sectional structure of the main cell region of the semiconductor device of the modification.
- Embodiments of the semiconductor device will be described below with reference to the drawings.
- the embodiments shown below are examples of configurations and methods for embodying technical ideas, and the materials, shapes, structures, layouts, dimensions, etc. of each component are not limited to the following. .
- the semiconductor device 10 of this embodiment is a trench gate type IGBT (Insulated Gate Bipolar Transistor). This semiconductor device 10 is used, for example, as a switching element in an in-vehicle inverter device.
- IGBT Insulated Gate Bipolar Transistor
- the semiconductor device 10 is formed, for example, in the shape of a rectangular flat plate.
- the device main surface 10s of the semiconductor device 10 is formed, for example, in a square shape.
- the length of one side of the main surface 10s of the device is about 3.5 mm. That is, the chip size of the semiconductor device 10 of this embodiment is 3.5 mm square.
- the semiconductor device 10 has a device back surface 10r (see FIG. 2) facing away from the device main surface 10s, and four device side surfaces 10a to 10d formed between the device main surface 10s and the device back surface 10r. is doing.
- the device side surfaces 10a to 10d are surfaces connecting, for example, the device main surface 10s and the device rear surface 10r, and are perpendicular to both the device main surface 10s and the device rear surface 10r.
- the semiconductor device 10 includes an emitter electrode 21, a gate electrode 22, and a collector electrode 27 (see FIG. 3) as external electrodes for connecting the semiconductor device 10 to the outside.
- the emitter electrode 21 is an electrode forming the emitter of the IGBT, and is an electrode through which the main current of the semiconductor device 10 flows.
- the emitter electrode 21 is formed on the main surface 10s of the device.
- a concave portion 21a is formed in the emitter electrode 21 closer to the device side surface 10c than the center in the y direction and in the center in the x direction.
- the recess 21a opens toward the device side surface 10c.
- the gate electrode 22 is an electrode forming the gate of the IGBT, and is an electrode to which a drive voltage signal for driving the semiconductor device 10 is supplied from outside the semiconductor device 10 .
- the gate electrode 22 is formed on the main surface 10s of the device. Gate electrode 22 is formed in recess 21 a of emitter electrode 21 .
- the collector electrode 27 shown in FIG. 2 is an electrode that constitutes the collector of the IGBT, and is an electrode through which the main current of the semiconductor device 10 flows. That is, in the semiconductor device 10 , the main current flows from the collector electrode 27 toward the emitter electrode 21 .
- the collector electrode 27 constitutes the back surface 10r of the device.
- the semiconductor device 10 includes a main cell region 11 in which a plurality of main cells 11A (see FIG. 2) are formed, and a main cell region 11 provided outside the main cell region 11 so as to surround the main cell region 11. and a perimeter region 12 .
- the main cell region 11 is a region forming an IGBT.
- the peripheral region 12 is a region other than the main cell region 11 .
- An emitter electrode 21 is provided in the main cell region 11 .
- Emitter electrode 21 is formed over most of main cell region 11 .
- the emitter electrode 21 has a shape along the shape of the main cell region 11 when viewed in the z direction.
- the main cell 11A is not formed at a position overlapping the gate electrode 22 in the z direction. That is, the main cell region 11 has a concave portion 11a that is recessed so as to avoid the gate electrode 22. As shown in FIG.
- the outer peripheral region 12 is a region where a termination structure for improving the withstand voltage of the semiconductor device 10 is provided.
- the outer peripheral region 12 is formed on the outer peripheral portion of the main surface 10s of the device when viewed from the z direction.
- the peripheral region 12 is a region surrounding the emitter electrode 21 .
- a gate electrode 22 , a gate finger 23 , an emitter lead-out portion 24 , an FLR (Field Limiting Ring) portion 25 , and an equipotential ring 26 are provided in the outer peripheral region 12 .
- Emitter electrode 21, gate electrode 22, emitter lead-out portion 24, FLR portion 25, and equipotential ring 26 include a common metal film. This metal film is made of, for example, a material containing AlCu (alloy of aluminum and copper).
- the gate finger 23 is configured to quickly supply the current supplied to the gate electrode 22 also to the main cell 11A in the portion of the emitter electrode 21 away from the gate electrode 22 .
- Gate finger 23 is connected to gate electrode 22 .
- the gate fingers 23 are provided so as to surround the main cell region 11 when viewed from the z direction. It can be said that the gate finger 23 is provided so as to surround the emitter electrode 21 when viewed from the z direction. Gate finger 23 has a metal wire provided at the same position as emitter electrode 21 and gate electrode 22 in the z-direction.
- the gate finger 23 includes gate fingers 23A and 23B.
- Gate finger 23A extends from gate electrode 22 toward device side surface 10a and is formed to surround main cell region 11 from device side surface 10c, device side surface 10a, and device side surface 10d.
- Gate finger 23B extends from gate electrode 22 toward device side surface 10b and is formed to surround main cell region 11 from device side surfaces 10c, 10b and 10d.
- the tips of the gate fingers 23A and the tips of the gate fingers 23B face each other with a gap in the x direction at a portion closer to the device side surface 10d than the emitter electrode 21 is.
- the emitter lead-out portion 24 is a portion that is integrated with the emitter electrode 21, and is formed in an annular shape so as to surround the pair of gate fingers 23A and 23B. It can also be said that the emitter lead-around portion 24 is formed in an annular shape so as to surround the main cell region 11 when viewed from the z direction.
- the FLR portion 25 is a termination structure for improving the breakdown voltage of the semiconductor device 10 and is provided outside the emitter electrode 21 .
- FLR portion 25 is formed in a ring shape surrounding emitter electrode 21 and gate electrode 22 .
- the FLR portion 25 is formed in a closed annular shape.
- the FLR portion 25 has a function of improving the withstand voltage of the semiconductor device 10 by alleviating the electric field in the outer peripheral region 12 and suppressing the influence of external ions.
- the equipotential ring 26 is a termination structure for improving the breakdown voltage of the semiconductor device 10 and is formed in a ring so as to surround the FLR section 25 .
- the equipotential ring 26 is formed as a closed ring.
- the equipotential ring 26 has a function of improving the withstand voltage of the semiconductor device 10 .
- FIG. 2 shows an example of a cross-sectional structure of part of the main cell region 11 and part of the peripheral region 12 .
- hatching of some of the constituent elements of the semiconductor device 10 in the main cell region 11 is omitted for the sake of convenience.
- the semiconductor device 10 has a semiconductor substrate 30 .
- Semiconductor substrate 30 is made of a material containing, for example, n ⁇ -type Si (silicon).
- Semiconductor substrate 30 has a thickness of, for example, 50 ⁇ m or more and 200 ⁇ m or less.
- the semiconductor substrate 30 has a substrate front surface 30s and a substrate rear surface 30r facing opposite sides in the z-direction. In other words, the z direction can also be said to be the thickness direction of the semiconductor substrate 30 .
- the semiconductor substrate 30 has a structure in which a p + -type collector layer 31, an n-type buffer layer 32, and an n ⁇ -type drift layer 33 are laminated in order from the substrate back surface 30r toward the substrate surface 30s. .
- a collector electrode 27 is formed on the substrate rear surface 30r. The collector electrode 27 is formed over substantially the entire surface of the substrate rear surface 30r. The surface of the collector electrode 27 opposite to the substrate back surface 30 r constitutes the device back surface 10 r of the semiconductor device 10 .
- collector layer 31 As the p-type dopant of collector layer 31, for example, B (boron), Al (aluminum), or the like is used.
- the impurity concentration of collector layer 31 is, for example, 1 ⁇ 10 15 cm ⁇ 3 or more and 2 ⁇ 10 19 cm ⁇ 3 or less.
- n-type dopants for buffer layer 32 and drift layer 33 for example, N (nitrogen), P (phosphorus), As (arsenic), or the like is used.
- the impurity concentration of buffer layer 32 is, for example, 1 ⁇ 10 15 cm ⁇ 3 or more and 5 ⁇ 10 17 cm ⁇ 3 or less.
- the impurity concentration of drift layer 33 is lower than that of buffer layer 32, and is, for example, 1 ⁇ 10 13 cm ⁇ 3 or more and 5 ⁇ 10 14 cm ⁇ 3 or less.
- a p-type base region 34 is formed on the surface of the drift layer 33, that is, the substrate surface 30s.
- the base region 34 is formed over substantially the entire surface of the main cell region 11 .
- the impurity concentration of base region 34 is, for example, 1 ⁇ 10 16 cm ⁇ 3 or more and 1 ⁇ 10 18 cm ⁇ 3 or less.
- the depth of base region 34 from substrate surface 30s is, for example, 1.0 ⁇ m or more and 3.0 ⁇ m or less.
- An interface 39A is formed between the drift layer 33 and the base region 34 .
- the p-type base region 34 corresponds to the "second conductivity type body region".
- a trench 35 is provided in the surface of the drift layer 33 (substrate surface 30s) in the main cell region 11 .
- a plurality of trenches 35 are provided in a state of being spaced apart from each other and arranged.
- Each trench 35 extends, for example, along the y direction and is arranged apart from each other in the x direction.
- the main cells 11A are divided into stripes.
- the distance between adjacent trenches 35 in the x-direction is, for example, 0.5 ⁇ m or more and 1.5 ⁇ m or less.
- the width of each trench 35 is, for example, 0.5 ⁇ m or more and 1.5 ⁇ m or less.
- the interval between the trenches 35 adjacent to each other in the x direction is equal to or less than the width of the trenches 35 .
- the distance D between the trenches 35 adjacent in the arrangement direction of the trenches 35 is equal to or less than the width dimension Wt of the trenches 35 .
- the trenches 35 may be formed in a grid pattern so as to partition the main cells 11A arranged in rows and columns.
- Each trench 35 extends in the z-direction to reach the drift layer 33 through the base region 34 . That is, each trench 35 penetrates the base region 34 in the z-direction and extends halfway through the drift layer 33 . Thereby, the z direction becomes the depth direction of the trench 35 . More specifically, each trench 35 extends in the z-direction from the surface of the drift layer 33 (substrate surface 30s). Each trench 35 extends through the base region 34 to reach a region of the drift layer 33 closer to the substrate back surface 30 r than the base region 34 . In this embodiment, the depth of the trench 35 is approximately 6.0 ⁇ m.
- a column region 38 of the second conductivity type (p-type) is provided at the position of the bottom 35a of each trench 35 in the drift layer 33 . That is, the column regions 38 are individually provided for the plurality of trenches 35 corresponding to the plurality of trenches 35 . For this reason, a plurality of column regions 38 are provided in a state of being arranged apart from each other. In this embodiment, each column region 38 is electrically floating.
- Column region 38 is formed to cover the entire bottom portion 35 a of corresponding trench 35 . That is, the width dimension Wc of the column region 38 is greater than or equal to the width dimension Wt of the trench 35 .
- the width dimension Wt of the trenches 35 is the dimension of the trenches 35 in the arrangement direction of the trenches 35
- the width dimension Wc of the column regions 38 is the dimension of the column regions 38 in the arrangement direction of the trenches 35 .
- the depth of column region 38 from bottom portion 35a of trench 35 (hereinafter, depth Hc of column region 38) is, for example, 1 ⁇ m or more and 2 ⁇ m or less. In this embodiment, the depth Hc of the column region 38 is approximately 1.5 ⁇ m.
- the width dimension Wc of the column region 38 is the x-direction dimension of the column region 38
- the depth Hc of the column region 38 is the z-direction dimension of the column region 38 from the bottom 35 a of the trench 35 .
- the column region 38 is formed such that the depth Hc of the column region 38 is larger than the width dimension Wc (Wc ⁇ Hc).
- the impurity concentration of the column region 38 is lower than that of the base region 34, and is, for example, 1.0 ⁇ 10 15 cm ⁇ 3 or more and 5.0 ⁇ 10 17 cm ⁇ 3 or less.
- n + -type emitter region 36 is formed on the surface (substrate surface 30 s ) of the base region 34 in the main cell region 11 .
- the emitter regions 36 are arranged on both sides of the trench 35 in the x direction. That is, it can be said that the emitter regions 36 are provided on both sides of the trenches 35 in the arrangement direction of the trenches 35 in the base region 34 . Therefore, two emitter regions 36 are spaced apart from each other in the x direction between the trenches 35 adjacent to each other in the x direction.
- the depth of each emitter region 36 is, for example, 0.2 ⁇ m or more and 0.6 ⁇ m or less.
- the impurity concentration of each emitter region 36 is higher than that of the base region 34, and is, for example, 1 ⁇ 10 19 cm ⁇ 3 or more and 5 ⁇ 10 20 cm ⁇ 3 or less.
- a p + -type base contact region 37 is formed on the surface (substrate surface 30 s ) of the base region 34 in the main cell region 11 .
- the base contact region 37 is provided at a position adjacent to the emitter region 36 in the x direction. That is, the base contact region 37 is provided between two emitter regions 36 provided between trenches 35 adjacent in the x direction in the x direction.
- Each base contact region 37 may be formed deeper than the emitter region 36 .
- the depth of each base contact region 37 is, for example, 0.2 ⁇ m or more and 0.8 ⁇ m or less.
- the impurity concentration of each base contact region 37 is higher than that of the base region 34, for example, 5 ⁇ 10 18 cm ⁇ 3 or more and 1 ⁇ 10 20 cm ⁇ 3 or less.
- a base contact region 37 is formed within the base region 34 . Therefore, it can be said that the base region 34 includes the base contact region 37 as a region of high impurity concentration in the base region 34 .
- Insulating film 41 is integrally formed on both the inner surface of each trench 35 and the substrate surface 30s. Therefore, it can be said that the insulating film 41 is formed on the surface of the drift layer 33 .
- Insulating film 41 has, for example, silicon oxide (SiO 2 ).
- the thickness of insulating film 41 is, for example, 1100 ⁇ or more and 1300 ⁇ or less. It can be said that the insulating film 41 in the main cell region 11 constitutes a gate insulating film.
- the insulating film 41 formed on the substrate front surface 30s has a rear surface 41r facing the same side as the substrate rear surface 30r. In this embodiment, the back surface 41r of the insulating film 41 is in contact with the substrate front surface 30s.
- An electrode material made of, for example, polysilicon is embedded in each trench 35 with an insulating film 41 interposed therebetween.
- the electrode material embedded in each trench 35 is electrically connected to either the gate electrode 22 (gate finger 23 ) or the emitter electrode 21 . That is, the electrode material embedded in each trench 35 forms the gate trench 22A and the emitter trench 21A.
- the gate trenches 22A and the emitter trenches 21A are alternately provided in the arrangement direction of the plurality of trenches 35 .
- both the gate trench 22A and the emitter trench 21A are filled up to the opening end of each trench 35 . It can be said that the gate trench 22A constitutes a part of the gate electrode 22 (see FIG. 1).
- An intermediate insulating film 42 is formed on the surface 41s of the insulating film 41 provided on the substrate surface 30s.
- Intermediate insulating film 42 has, for example, SiO 2 .
- the thickness of the intermediate insulating film 42 is thicker than that of the insulating film 41 and is 3000 ⁇ or more and 15000 ⁇ or less.
- An emitter electrode 21 is formed on the surface 42 s of the intermediate insulating film 42 .
- the intermediate insulating film 42 is an interlayer insulating film that fills both the space between the emitter electrode 21 and the gate trench 22A and the space between the emitter electrode 21 and the emitter trench 21A.
- a contact hole 43 exposing the base contact region 37 is formed in both the intermediate insulating film 42 and the insulating film 41 in the main cell region 11 .
- the contact hole 43 is formed for each trench 35 in the main cell region 11 .
- a portion of emitter electrode 21 is embedded in contact hole 43 and is in contact with base contact region 37 .
- the emitter electrode 21 has an electrode body portion 21 c formed on the surface 42 s of the intermediate insulating film 42 and a plurality of embedded electrode portions 21 b individually embedded in the plurality of contact holes 43 .
- the electrode body portion 21c and each embedded electrode portion 21b are provided separately.
- the electrode body portion 21c is provided on each embedded electrode portion 21b.
- a barrier metal layer 21 e is formed on the surface 42 s of the intermediate insulating film 42 and the inner surfaces of the intermediate insulating film 42 and the insulating film 41 forming the contact hole 43 .
- Barrier metal layer 21e is formed of, for example, a laminated structure of Ti (titanium) and TiN (titanium nitride). Both the embedded electrode portion 21b and the electrode body portion 21c are formed on the barrier metal layer 21e.
- FIG. 3 is an enlarged view of part of the main cell 11A in the main cell region 11 of FIG.
- FIG. 4 is a graph showing an example of the impurity concentration distribution on the first straight line L1 and the second straight line L2, which are dashed lines extending in the z direction in the main cell 11A of FIG.
- the first straight line L1 is located between the trenches 35 adjacent in the x direction.
- the second straight line L2 is positioned inside the trench 35 .
- the solid-line graph G1 in FIG. 4 is a graph showing the impurity concentration distribution on the first straight line L1, and the dashed-dotted line graph G2 in FIG.
- FIG. 4 is a graph showing the impurity concentration distribution on the second straight line L2.
- the horizontal axis indicates the depth from the surface of the drift layer 33 (substrate surface 30s), and the vertical axis indicates the impurity concentration.
- the components of the semiconductor device 10 shown in FIG. 3 are referred to.
- a region with a depth H1 or more and a depth H2 or less corresponds to the base region 34, and a region deeper than the depth H2 corresponds to a region of the drift layer 33 closer to the substrate back surface 30r than the base region 34.
- Depth H2 corresponds to interface 39A between drift layer 33 and base region 34 .
- a depth H4 deeper than the depth H2 corresponds to the bottom 35a of the trench 35.
- a region having a depth H4 or more and a depth H5 or less corresponds to the column region 38 .
- Depth H5 corresponds to interface 39B between drift layer 33 and column region 38 .
- Interface 39B is an interface between bottom surface 38a of column region 38 and drift layer 33 .
- a region of the drift layer 33 adjacent to the base region 34 in the z direction is referred to as a first region 33A, and a region of the drift layer 33 formed in the same position as the column region 38 in the z direction is referred to as a first region 33A.
- a region including the drift layer 33 is referred to as a second region 33B, and a region deeper than the column region 38 in the drift layer 33 in the z direction is referred to as a third region 33C. That is, the drift layer 33 has a first region 33A, a second region 33B, and a third region 33C.
- the first region 33A, the second region 33B, and the third region 33C are formed apart from each other in the z direction.
- the first region 33A is a region deeper than the depth H2 and less than or equal to the depth H3. It can also be said that the first region 33A is a region near the interface 39A between the drift layer 33 and the base region 34 .
- the first region 33A has a first concentration peak CP1. More specifically, in the first region 33A, the impurity concentration increases as the depth increases from the depth H2, and the impurity concentration reaches the first concentration peak CP1 at the depth HA.
- the first concentration peak CP1 is, for example, 9 ⁇ 10 16 cm ⁇ 3 .
- the impurity concentration decreases as the depth increases from the depth HA.
- the impurity concentration of first region 33A is, for example, higher than 1 ⁇ 10 16 cm ⁇ 3 and lower than 1 ⁇ 10 17 cm ⁇ 3 .
- the degree of impurity concentration decreases as the depth increases from the depth HA.
- the impurity concentration decreases as the depth of the drift layer 33 increases.
- the impurity concentration decreases as the depth of the drift layer 33 increases.
- the degree of lowering of the impurity concentration is smaller than in the region deeper than the depth HA and equal to or less than the depth H3.
- the impurity concentration gradually increases as the depth of drift layer 33 increases.
- the impurity concentration is lowest at depth HC.
- the impurity concentration at the depth HC is, for example, higher than 1 ⁇ 10 15 cm ⁇ 3 and lower than 2 ⁇ 10 15 cm ⁇ 3 .
- the impurity concentration gradually decreases as the depth of the drift layer 33 increases. , the impurity concentration is kept high as a whole.
- the second region 33B is a region from depth H4 to depth H5.
- the second region 33B is formed at the same position as the column region 38 in the z direction (depth direction). It can also be said that the second region 33B is a region provided at a position deeper than the bottom 35a of the trench 35 and corresponding to the column region 38 .
- the second region 33B has a portion provided at the same position as the column region 38 in the depth direction as a position corresponding to the column region 38 .
- the second region 33B has a second concentration peak CP2 lower than the first concentration peak CP1. More specifically, in the second region 33B, the impurity concentration increases as the depth increases from the depth H4, and the impurity concentration reaches the second concentration peak CP2 at the depth HB.
- the depth HB is the position overlapping the column region 38 in the z direction (depth direction). That is, the second region 33B has the highest impurity concentration at the position overlapping the column region 38 in the z direction.
- the impurity concentration decreases from depth HB to depth H5.
- the second concentration peak CP2 is, for example, 2 ⁇ 10 15 cm ⁇ 3 .
- the impurity concentration of second region 33B is, for example, higher than 1 ⁇ 10 14 cm ⁇ 3 and not higher than 2 ⁇ 10 15 cm ⁇ 3 .
- the impurity concentration decreases as the depth of the drift layer 33 increases. That is, the impurity concentration in this region is higher than the impurity concentration at depth H6.
- the third region 33C is a region with a depth of H6 or less. Depth H6 is a region deeper than column region 38 . This is the region with the lowest impurity concentration in the drift layer 33 .
- the third region 33C forms an end portion of the drift layer 33 closer to the substrate back surface 30r in the z direction (the depth direction in FIG. 4).
- the impurity concentration is constant even when the depth increases from the depth H6.
- the impurity concentration of the third region 33C is, for example, 1 ⁇ 10 14 cm ⁇ 3 . Therefore, it can be said that the second concentration peak CP2 of the second region 33B is higher than the impurity concentration of the third region 33C.
- the impurity concentration of the region between the second region 33B and the third region 33C in the depth direction (z direction) of the drift layer 33 (the region deeper than the depth H5 and shallower than the depth H6) is , higher than the impurity concentration of the third region 33C.
- the maximum impurity concentration CM1 of the column region 38 is higher than the second concentration peak CP2 of the second region 33B. Furthermore, the maximum impurity concentration CM1 of the column region 38 is higher than the first concentration peak CP1 of the first region 33A. On the other hand, the impurity concentration of the column region 38 is lower than that of the base region 34 . It can also be said that the maximum impurity concentration CM1 of the column region 38 is lower than the maximum impurity concentration CM2 of the base region 34 .
- the impurity concentration of the column region 38 is higher than that of the second region 33B over substantially the entire column region 38. More specifically, the impurity concentration of the column region 38 is higher than that of the second region 33B except near the interface 39B (near the depth H5).
- the range of the first region 33A in the z direction (depth direction) can be arbitrarily changed.
- the first region 33A may include regions deeper than the depth H3.
- the first region 33A may be a region from depth H2 to depth HC.
- the first region 33A may be a region from depth H2 to depth H4.
- the range of the second region 33B in the z direction can be arbitrarily changed.
- the second region 33B may include regions shallower than the depth H4.
- the second region 33B may be a region from depth HC to depth H5.
- the first region 33A is a region from depth H2 to depth H3 or a region from depth H2 to depth HC.
- the second region 33B may be a region from depth H3 to depth H5.
- the first region 33A is a region from depth H2 to depth H3.
- the second region 33B may include a region deeper than the depth H5.
- the second region 33B is a region from depth H4 to depth H6. That is, the second region 33B may be a region from depth H3 to depth H6. In this manner, the second region 33B may have a portion provided at a position shifted from the column region 38 in the depth direction as a position corresponding to the column region 38 .
- a method for manufacturing the semiconductor device 10 of this embodiment will be described with reference to FIGS.
- a method for manufacturing the main cell region 11 will be described below.
- the manufacturing method of one semiconductor device 10 will be described with reference to FIGS.
- the manufacturing method of the semiconductor device 10 of the present embodiment is not limited to manufacturing one semiconductor device 10, and may be manufacturing a plurality of semiconductor devices 10. FIG.
- the method for manufacturing the semiconductor device 10 of this embodiment includes a step of preparing a semiconductor substrate 830 made of a material containing Si.
- the semiconductor substrate 830 has an n ⁇ -type drift layer 33 as a first conductivity type semiconductor layer.
- Drift layer 33 is formed over the entire semiconductor substrate 830 .
- Drift layer 33 has an impurity concentration of, for example, 1 ⁇ 10 14 cm ⁇ 3 .
- the semiconductor substrate 830 has a substrate front surface 830s and a substrate rear surface (not shown) facing opposite sides in the thickness direction (z direction). Therefore, it can be said that the substrate surface 830 s is the surface of the drift layer 33 .
- the method for manufacturing the semiconductor device 10 of this embodiment includes a step of forming a plurality of trenches 835 in the semiconductor substrate 830.
- a trench mask (not shown) is formed on the substrate surface 830 s of the semiconductor substrate 830 .
- the trench mask is then selectively etched. That is, the region of the trench mask where the trench 835 is to be formed is etched as viewed in the z-direction.
- the trench mask exposes regions of the substrate surface 830s of the semiconductor substrate 830 where the trenches 835 are to be formed.
- a region of the substrate surface 830s of the semiconductor substrate 830 where the trench 835 is to be formed is etched. A trench 835 is thereby formed in the semiconductor substrate 830 .
- the method of manufacturing the semiconductor device 10 of this embodiment includes a step of forming a sacrificial oxide film 850 on the surfaces of the plurality of trenches 835 and the semiconductor substrate 830 .
- Sacrificial oxide film 850 is formed by thermally oxidizing semiconductor substrate 830 .
- Sacrificial oxide film 850 is formed of a material including silicon oxide film (SiO 2 ), for example.
- the method of manufacturing the semiconductor device 10 of the present embodiment includes a step of implanting first conductivity type (n-type) impurities into the drift layer 33 .
- impurities are implanted and diffused into drift layer 33 from trenches 835 in a direction oblique to the z-direction. In one example, it is implanted and diffused into the drift layer 33 through the trenches 835 from a direction angled 7° with respect to the z-direction.
- a first region 33A, a second region 33B, and a third region 33C are formed in the drift layer 33 .
- the first region 33A becomes a region having the first concentration peak CP1.
- the impurity concentration of first region 33A is, for example, higher than 1 ⁇ 10 15 cm ⁇ 3 and lower than 1 ⁇ 10 17 cm ⁇ 3 .
- the second region 33B is a region having a second concentration peak CP2 lower than the first concentration peak CP1.
- the impurity concentration of second region 33B is, for example, higher than 1 ⁇ 10 14 cm ⁇ 3 and 2 ⁇ 10 15 cm ⁇ 3 or less.
- the third region 33C is a region closer to the back surface of the substrate than the trench 835 is.
- the impurity concentration of the third region 33C is, for example, 1 ⁇ 10 14 cm ⁇ 3 .
- the method of manufacturing the semiconductor device 10 of this embodiment includes steps of forming the base region 34 and the column region 38 .
- impurities of the second conductivity type p-type
- the base region 34 is formed by implanting and diffusing the p-type impurity into the drift layer 33 between the trenches 835 adjacent in the x direction.
- Column region 38 is formed by implanting and diffusing a p-type impurity into bottom 835 a of trench 835 through trench 835 .
- the impurity concentration of base region 34 is, for example, 1 ⁇ 10 16 cm ⁇ 3 or more and 1 ⁇ 10 18 cm ⁇ 3 or less.
- the impurity concentration of the column region 38 is, for example, 1.0 ⁇ 10 15 cm ⁇ 3 or more and 5.0 ⁇ 10 17 cm ⁇ 3 or less.
- the method for manufacturing the semiconductor device 10 of this embodiment includes a step of forming an insulating film 841 and a step of forming an electrode.
- the semiconductor substrate 830 is thermally oxidized to form an oxide film on the entire surface of the semiconductor substrate 830 including the inner surface of each trench 835 .
- an insulating film 841 is formed on the substrate surface 830 s of the semiconductor substrate 830 .
- the insulating film 841 is an insulating film corresponding to the insulating film 41 .
- the insulating film 841 in the main cell region 11 is a gate insulating film and is also formed on the inner surface of each trench 835 .
- an electrode material PS such as polysilicon is embedded in each trench 835 and formed on the substrate surface 830 s of the semiconductor substrate 830 .
- the gate trench 22A and the emitter trench 21A are formed.
- the electrode material PS in the main cell region 11 of the substrate surface 830s of the semiconductor substrate 830 is removed by etching.
- the electrode material PS embedded in each trench 835 is oxidized. Thereby, an insulating film 841 is formed on the electrode material PS.
- the manufacturing method of the semiconductor device 10 of this embodiment includes a step of forming the emitter region 36.
- n + -type emitter region 36 is formed by selectively implanting and diffusing n-type impurity ions into substrate surface 830 s of semiconductor substrate 830 .
- the impurity concentration of the emitter region 36 is higher than that of the base region 34, for example, 1 ⁇ 10 19 cm ⁇ 3 or more and 5 ⁇ 10 20 cm ⁇ 3 or less.
- the method of manufacturing the semiconductor device 10 of this embodiment includes the steps of forming an intermediate insulating film 842, forming an opening, and forming a base contact region 37.
- the intermediate insulating film 842 is formed over the entire substrate surface 830s of the semiconductor substrate 830 by chemical vapor deposition (CVD), for example.
- the intermediate insulating film 842 is formed on the surface 841 s of the insulating film 841 .
- the intermediate insulating film 842 is an insulating film corresponding to the intermediate insulating film 42 .
- An intermediate insulating film 842 is stacked on the insulating film 841 .
- the insulating film covering the substrate surface 830 s of the semiconductor substrate 830 has a two-layer structure of the insulating film 841 and the intermediate insulating film 842 formed on the substrate surface 830 s of the semiconductor substrate 830 .
- An opening 843 is formed through the intermediate insulating film 842 and the insulating film 841 by etching. Opening 843 exposes base region 34 . Thereby, an insulating film 41 and an intermediate insulating film 42 are formed.
- a p + -type base contact region 37 is formed by ion-implanting and diffusing a p-type dopant through the opening 843 into the substrate surface 830s of the semiconductor substrate 830 .
- the impurity concentration of base contact region 37 is, for example, 5 ⁇ 10 18 cm ⁇ 3 or more and 1 ⁇ 10 20 cm ⁇ 3 or less.
- the manufacturing method of the semiconductor device 10 of this embodiment includes a step of forming the emitter electrode 21.
- a first metal layer is formed on the surface 42s of the intermediate insulating film 42 and the inner surface of the opening 843 by, for example, sputtering using titanium (Ti).
- a second metal layer is formed on the first metal layer by sputtering using titanium nitride (TiN).
- TiN titanium nitride
- a barrier metal layer 21e is formed.
- an electrode layer 821 is formed by sputtering using AlCu.
- the electrode layer 821 is formed over the entire intermediate insulating film 42 when viewed from the z direction.
- the emitter electrode 21 is then formed by etching the electrode layer 821 .
- the method of manufacturing the semiconductor device 10 of this embodiment includes steps of forming the buffer layer 32 , the collector layer 31 and the collector electrode 27 .
- the buffer layer 32 and the collector layer 31 are formed in order by ion-implanting and diffusing n-type and p-type dopants to the back surface of the semiconductor substrate 830 .
- a collector electrode 27 is formed on the surface of the collector layer 31 opposite to the buffer layer 32 .
- FIG. 12 shows the cross-sectional structure of the main cell region 11 of the semiconductor device 10X of Experimental Example 1.
- FIG. 13 shows the cross-sectional structure of the main cell region 11 of the semiconductor device 10Y of Experimental Example 2.
- a dashed line graph GR in FIG. 4 is a graph showing the impurity concentration distribution on the first straight line L1 of the semiconductor devices 10X and 10Y. Note that the semiconductor device 10 of this embodiment is treated as Experimental Example 3.
- semiconductor devices 10X and 10Y are different from semiconductor device 10 in that column region 38 and second region 33B and third region 33C of drift layer 33 are omitted. configuration.
- the semiconductor device 10Y has a configuration in which the arrangement pitch of the trenches 35 is narrower than that of the semiconductor device 10X.
- the distance DY between the trenches 35 adjacent in the x direction in the semiconductor device 10Y is equal to the distance D (see FIG. 3) between the trenches 35 adjacent in the x direction in the semiconductor device 10 in this embodiment. That is, the distance DX between the trenches 35 adjacent in the x direction in the semiconductor device 10X is larger than the distance D between the trenches 35 adjacent in the x direction in the semiconductor device 10 in this embodiment. Since the area of the main cell region 11 viewed from the z-direction is the same among the semiconductor devices 10, 10X, and 10Y, the number of main cells in the semiconductor device 10X is smaller than the number of main cells in the semiconductor devices 10 and 10Y. .
- the first regions 33A of the drift layers 33 of the semiconductor devices 10X and 10Y have the first concentration peak CP1 at the depth HA, like the semiconductor device 10.
- the degree of decrease in impurity concentration is greater than that of the first region 33A of the semiconductor device 10 as the depth increases from the first concentration peak CP1.
- the impurity concentration is, for example, 1 ⁇ 10 14 cm ⁇ 3 . That is, in the semiconductor devices 10X and 10Y, the impurity concentration is the same as the depth H6 in the semiconductor device 10 at the depth HT which is shallower than the bottom portion 35a of the trench 35 .
- the impurity concentration is, for example, 1 ⁇ 10 14 cm ⁇ 3 in the region of the drift layer 33 at the depth HT or less. That is, the impurity concentration in the region between the first region 33A and the second region 33B in the semiconductor device 10 is higher than the impurity concentration in the region deeper than the depth HT in the drift layers 33 of the semiconductor devices 10X and 10Y. . Further, the impurity concentration of the region between the first region 33A and the second region 33B in the semiconductor device 10 is the region ( higher than the impurity concentration of the region deeper than the depth H3 and not more than the depth H4 in the semiconductor devices 10X and 10Y.
- the difference between the impurity concentration in the region between the first region 33A and the second region 33B in the semiconductor device 10 and the impurity concentration in the region deeper than the depth H3 and not more than the depth H4 in the semiconductor devices 10X and 10Y increases from depth H3 to depth H4.
- FIG. 14 is a graph showing the relationship between the electric field intensity of the drift layer 33 and the position of the drift layer 33 in the z direction in Experimental Examples 1-3.
- FIG. 14 shows a simulation result when a voltage of 1000 V is applied between the collector and emitter while the collector and emitter are short-circuited.
- the electric field strength of Experimental Example 3 is lower than the electric field strengths of Experimental Examples 1 and 2. That is, in Experimental Example 3, since the column region 38 is provided at the position of the bottom portion 35a of the trench 35, electric field concentration at the bottom portion 35a of the trench 35 is reduced. On the other hand, in Experimental Examples 1 and 2, since the column region 38 is not formed at the position of the bottom portion 35a of the trench 35, electric field concentration occurs at the bottom portion 35a of the trench 35.
- FIG. 15 is a graph showing the relationship between the collector-emitter saturation voltage Vce(sat) and the loss Eoff when the semiconductor device is turned off in Experimental Examples 1-3.
- the collector-emitter saturation voltage Vce(sat) is lower than in experimental examples 1 and 2 at the same loss Eoff at turn-off.
- Experimental Example 3 has a lower loss Eoff than Experimental Examples 1 and 2 at the collector-emitter voltage Vce at the time of turn-off.
- Experimental Example 3 can be designed to reduce both loss Eoff and collector-emitter saturation voltage Vce(sat) at the time of turn-off more than Experimental Examples 1 and 2.
- FIG. 16 is a graph showing the relationship between the collector-emitter saturation voltage Vce(sat) and the loss Eon when the semiconductor device is turned on in Experimental Examples 1-3.
- the loss Eon at the same collector-emitter saturation voltage Vce(sat) is greater than in Experimental Example 1 and smaller than in Experimental Example 2.
- FIG. The reason for this is considered to be that in Experimental Examples 2 and 3, the number of main cells 11A is larger than that in Experimental Example 1, resulting in an increase in mirror capacitance.
- the column region 38 is provided in the bottom portion 35a of the trench 35, an increase in the mirror capacitance is suppressed.
- the loss Eon at the same collector-emitter saturation voltage Vce(sat) is smaller than in Experimental Example 2.
- FIG. 17 is a graph showing the relationship between the collector-emitter saturation voltage Vce(sat) and the total loss (hereinafter referred to as loss Etotal) in Experimental Examples 1-3.
- the loss Etotal is the sum of the loss Eoff at turn-on and the loss Eon at turn-off.
- Experimental Example 3 has a lower collector-emitter saturation voltage Vce(sat) than Experimental Examples 1 and 2 at the same loss Etotal.
- the loss Etotal at the collector-emitter voltage Vce is lower than in Experimental Examples 1 and 2.
- FIG. Thus, Experimental Example 3 can be designed to reduce both the loss Etotal and collector-emitter saturation voltage Vce(sat) more than Experimental Examples 1 and 2.
- FIG. 18 is a graph showing changes in collector current Ic, collector-emitter voltage Vce, and gate-emitter voltage Vge when the semiconductor device is turned on in Experimental Examples 1-3.
- a broken line graph indicates Experimental example 1
- a dashed line graph indicates Experimental example 2
- a solid line graph indicates Experimental example 3.
- the semiconductor device 10 includes a drift layer 33 of a first conductivity type (n-type), a base region 34 of a second conductivity type (p-type) formed on the surface side of the drift layer 33, and a base region 34 a trench 35 extending in the depth direction (z direction) so as to reach the drift layer 33 by penetrating the trench 35, an insulating film 41 formed on the inner surface of the trench 35, and a gate trench 22A surrounded by the insulating film 41. , and a column region 38 of the second conductivity type (p-type) provided at the position of the bottom 35 a of the trench 35 in the drift layer 33 .
- the drift layer 33 includes a first region 33A having a first concentration peak CP1 and a second concentration peak lower than the first concentration peak CP1, provided at a position deeper than the trench 35 and corresponding to the column region 38. and a second region 33B having CP2.
- the column regions 38 adjacent to each other in the arrangement direction (x direction) of the trenches 35 are brought closer due to miniaturization, the column regions 38 may be joined.
- the current flowing from the collector electrode 27 to the emitter electrode 21 must pass through the column region 38, so that the current from the collector electrode 27 to the emitter electrode 21 becomes difficult to flow.
- a second region 33B having a second concentration peak CP2 is provided at a position corresponding to the column region 38 in the drift layer 33.
- the impurity concentration of the second region 33B is relatively high, when the column regions 38 are formed, the expansion of the column regions 38 in the arrangement direction (x direction) of the trenches 35 can be suppressed. This can prevent the column regions 38 adjacent to each other in the arrangement direction of the trenches 35 from joining.
- a plurality of column regions 38 are provided corresponding to the plurality of trenches 35 . With this configuration, electric field concentration at the bottom 35a of each trench 35 can be reduced, so that the semiconductor device 10 can have a high withstand voltage.
- the second region 33B of the drift layer 33 is provided between the column regions 38 adjacent in the arrangement direction (x direction) of the trenches 35 . According to this configuration, when the column regions 38 are formed, it is possible to prevent the column regions 38 from spreading in the arrangement direction (x direction) of the trenches 35 . Thereby, it is possible to prevent the column regions 38 adjacent to each other in the arrangement direction of the trenches 35 from being joined to each other.
- the second region 33B of the drift layer 33 has a portion provided at the same position as the column region 38 in the depth direction (z direction) of the trench 35 . According to this configuration, when the column regions 38 are formed, it is possible to further suppress the expansion of the column regions 38 in the arrangement direction (x direction) of the trenches 35 . Thereby, it is possible to further suppress the joining of the column regions 38 adjacent to each other in the arrangement direction of the trenches 35 .
- Column region 38 is formed to cover the entire bottom 35a of trench 35 . With this configuration, electric field concentration at the bottom 35a of the trench 35 can be further reduced.
- the distance D between the trenches 35 adjacent in the arrangement direction (x direction) of the trenches 35 is equal to or less than the width dimension Wt of the trenches 35 .
- the expansion of the column regions 38 can be suppressed by the second regions 33B. can be suppressed. Therefore, the integration of the main cells 11A can be achieved while suppressing the column regions 38 from joining to each other.
- the above embodiments are examples of possible forms of the semiconductor device according to the present disclosure, and are not intended to limit the forms.
- a semiconductor device related to the present disclosure may take a form different from the forms illustrated in the above embodiments.
- One example is a form in which a part of the configuration of each of the above embodiments is replaced, changed, or omitted, or a form in which a new configuration is added to the above embodiment.
- each of the following modifications can be combined with each other as long as they are not technically inconsistent.
- the same reference numerals as those in the above-described embodiment are attached to the portions common to the above-described embodiment, and the description thereof will be omitted.
- the semiconductor device 10 may include the main cell region 11 forming the IGBT and the diode cell region 14 forming the free wheel diode connected to the IGBT.
- a semiconductor device 10 having such a diode cell region 14, that is, a so-called RC (Reverse Conducting)-IGBT will be described with reference to FIGS. 19 to 22.
- FIG. 20 to 22 will be described mainly about the differences from the configuration of the semiconductor device 10 according to the modification shown in FIG.
- multiple trenches 35 are provided over both the main cell region 11 and the diode cell region 14 .
- the emitter trenches 21A and the gate trenches 22A are alternately provided in the arrangement direction (x direction) of the trenches 35.
- an emitter trench 21A is provided at the end of the main cell region 11 adjacent to the diode cell region 14 .
- the emitter trench 21A is provided and the gate trench 22A is not provided.
- column regions 38 are provided at the bottoms 35a of the trenches 35 in both the main cell region 11 and the diode cell region 14 . That is, the column region 38 is provided at the position of the bottom portion 35a of the trench 35 formed in the main cell region 11, and is provided at the position of the bottom portion 35a of the trench 35 formed in the diode cell region 14.
- a base region 34 is provided on the surface of the drift layer 33 in both the main cell region 11 and the diode cell region 14 .
- An emitter region 36 and a base contact region 37 are provided in the main cell region 11 as in the above embodiments.
- diode cell region 14 is not provided with emitter region 36 and base contact region 37 . That is, the emitter region 36 and the base contact region 37 are selectively provided in the base region 34 of the main cell region 11 instead of the base region 34 of the diode cell region 14 .
- the collector layer 31 has a first conductivity type (n-type) first collector region 31A and a second conductivity type (p-type) second collector region 31B.
- the first collector region 31A is provided in the diode cell region 14 .
- the second collector region 31B is provided over the entire main cell region 11 . Also, the second collector region 31B is provided in part of the diode cell region 14 . Therefore, the diode cell region 14 has two regions, a first collector region 31A and a second collector region 31B.
- Both the insulating film 41 and the intermediate insulating film 42 are formed to cover both the main cell region 11 and the diode cell region 14 .
- a contact hole 43 penetrating both the insulating film 41 and the intermediate insulating film 42 is provided in the insulating film 41 and the intermediate insulating film 42 .
- Contact hole 43 is provided at a position corresponding to main cell region 11 and a position corresponding to diode cell region 14, respectively.
- the emitter electrode 21 is formed so as to cover both the main cell region 11 and the diode cell region 14 .
- the barrier metal layer 21e of the emitter electrode 21 is formed on the inner surface forming the contact hole 43 and the surface 42s of the intermediate insulating film 42 in both the main cell region 11 and the diode cell region .
- An electrode body portion 21c and a buried electrode portion 21b of the emitter electrode 21 are formed on the barrier metal layer 21e.
- Electrode body portion 21 c is formed on barrier metal layer 21 e formed on surface 42 s of intermediate insulating film 42 covering both main cell region 11 and diode cell region 14 .
- the embedded electrode portions 21b are individually embedded in a plurality of contact holes 43 in both the main cell region 11 and the diode cell region 14. As shown in FIG.
- the semiconductor device 10 of the modification shown in FIG. 20 has the intermediate insulating film 42 in the diode cell region 14 and the insulating film 41 in the portion other than the emitter trench 21A of the substrate surface 30s from the semiconductor device 10 shown in FIG. This is an omitted configuration. Accordingly, since the contact hole 43 is omitted in the diode cell region 14, the embedded electrode portion 21b is not provided in the portion of the emitter electrode 21 covering the diode cell region 14. FIG. In other words, the embedded electrode portion 21b is selectively provided in the emitter electrode 21 corresponding to the main cell region 11 instead of the diode cell region 14 . Further, the emitter electrode 21 has a step portion 21d.
- Stepped portion 21 d is provided at an end of diode cell region 14 forming a boundary with main cell region 11 .
- a barrier metal layer 21e is provided on the substrate surface 30s, and an electrode body portion 21c is provided on the barrier metal layer 21e.
- the modified semiconductor device 10 shown in FIG. 21 has a configuration in which the column regions 38 provided at the positions of the bottoms 35a of the trenches 35 of the diode cell regions 14 are omitted from the semiconductor device 10 shown in FIG.
- drift layer 33 corresponding to diode cell region 14 is not provided with first region 33A and second region 33B.
- the first region 33A and the second region 33B are selectively provided in the drift layer 33 corresponding to the main cell region 11 instead of the diode cell region 14 .
- the semiconductor device 10 of the modification shown in FIG. 22 is obtained by removing the intermediate insulating film 42 in the diode cell region 14 and the insulating film 41 in the portion of the substrate surface 30s other than the emitter trench 21A from the semiconductor device 10 shown in FIG. This is an omitted configuration.
- the configuration of the emitter electrode 21 is the same as the configuration of the emitter electrode 21 in FIG.
- the semiconductor device 10 may be provided with a floating region 50 of the second conductivity type (p-type) so as to surround the main cell region 11, as shown in FIG.
- Floating region 50 is in an electrically floating state.
- Floating region 50 is provided to be deeper than trench 35 .
- the emitter trenches 21A provided at both ends of the main cell region 11 in the arrangement direction of the trenches 35 do not constitute the main cell 11A.
- the floating region 50 is provided so as to cover the bottom 35a of the trench 35 of these emitter trenches 21A.
- floating region 50 is formed to partially cover bottom portion 35a of trench 35 of emitter trench 21A. Note that the floating region 50 may be formed so as to cover the entire bottom portion 35a of the trench 35 of the emitter trench 21A.
- the shape of the column region 38 cut along a plane along the depth direction of the trenches 35 and the arrangement direction of the trenches 35 in the above embodiment, and the shape of the column region 38 cut along a plane along the z direction and the x direction in this embodiment can be changed arbitrarily.
- the column region 38 may be formed with protruding regions 38b that widen in the x direction as they move away from the bottom 35a of the trench 35 toward the substrate back surface 30r in the z direction.
- the column region 38 is provided at a position spaced apart from the base region 34 in the z direction, but the present invention is not limited to this.
- the formation range of the column region 38 can be changed arbitrarily.
- the column region 38 may be formed so as to connect with the base region 34 . More specifically, the column region 38 includes a first column region provided at the position of the bottom portion 35a of the trench 35 in the drift layer 33 and a second column region extending from the first column region along the side surface of the trench 35 toward the base region 34 . a two-column region;
- the second column region is a connection region that connects the first column region and the base region 34 .
- the second column region extends, for example, along the depth direction of the trench 35 (the z-direction in the above embodiment). Two second column regions formed between adjacent trenches 35 in the arrangement direction of trenches 35 are separated from each other in the arrangement direction of trenches 35 . That is, the drift layer 33 is formed between the two second column regions in the arrangement direction of the trenches 35 .
- the column region 38 is formed so as to cover the entire bottom portion 35a of the trench 35, but is not limited to this. In one example, the column region 38 may be formed to partially cover the bottom 35 a of the trench 35 .
- the distance D between the trenches 35 adjacent in the arrangement direction of the trenches 35 is equal to or less than the width dimension Wt of the trenches 35, but is not limited to this. Distance D may be greater than width dimension Wt.
- the column regions 38 are formed corresponding to all the trenches 35, but the invention is not limited to this.
- the column region 38 may not be provided in the main cell region 11 at the bottom portion 35a of the trench 35 that does not form the main cell 11A.
- the column regions 38 may be selectively provided at the positions of the bottom portions 35 a of the plurality of trenches 35 . In other words, the column region 38 may not be provided at the position of the bottom portion 35a of the trench 35 that constitutes the main cell 11A.
- the gate trenches 22A and the emitter trenches 21A in the main cell region 11 are alternately arranged in the arrangement direction of the trenches 35 (the x-direction in the above-described embodiment), but the present invention is not limited to this.
- gate trenches 22A and emitter trenches 21A may be arranged in the arrangement direction of trenches 35 as gate trenches 22A, emitter trenches 21A, emitter trenches 21A, emitter trenches 21A, and gate trenches 22A.
- the semiconductor device 10 may be a planar gate type IGBT instead of the trench gate type IGBT.
- the semiconductor device 10 is embodied as an IGBT in the above embodiment, the semiconductor device 10 is not limited to this and may be a trench-type SiCMOSFET (metal-oxide-semiconductor field-effect transistor) or SiMOSFET. In this case, the source electrode of the MOSFET corresponds to the "drive electrode".
- CMOSFET metal-oxide-semiconductor field-effect transistor
- on as used in this disclosure includes the meanings of “on” and “above” unless the context clearly indicates otherwise.
- the expression “A is formed on B” means that although in this embodiment A may be placed directly on B with contact with B, A may alternatively be placed on B without contacting B. It is intended that it can be positioned above. That is, the term “on” does not exclude structures in which other members are formed between A and B.
- the z-direction used in the present disclosure does not necessarily have to be the vertical direction, nor does it have to match the vertical direction perfectly.
- the various structures according to this disclosure are not limited to the z-direction "top” and “bottom” described herein being the vertical “top” and “bottom”.
- the x-direction may be vertical, or the y-direction may be vertical.
- the drift layer (33) is a first region (33A) having a first concentration peak (CP1); A second region (a second region ( 33B), and a semiconductor device (10).
- Appendix 2 A plurality of trenches (35) are provided in a state of being spaced apart from each other and arranged, The semiconductor device according to appendix 1, wherein a plurality of the column regions (38) are provided corresponding to the plurality of trenches (35).
- the first region (33A) is provided between the trenches (35) adjacent in the arrangement direction (x direction) of the trenches (35),
- the semiconductor device according to appendix 2 wherein the second region (33B) is provided between the column regions (38) adjacent to each other in the arrangement direction (x direction) of the trenches (35).
- Appendix 4 The semiconductor device according to Appendix 3, wherein the first region (33A) is provided near an interface (39A) between the drift layer (33) and the body region (34).
- the second region (33B) has a portion provided at the same position as the column region (38) in the depth direction (z direction) of the trench (35) as a position corresponding to the column region (38).
- the second region (33B) is a portion provided at a position corresponding to the column region (38) at a position shifted from the column region (38) in the depth direction (z direction) of the trench (35).
- a distance (D) between the trenches (35) adjacent to each other in the arrangement direction (x direction) of the trenches (35) is equal to or less than the width dimension (Wt) of the trenches (35) Any one of Appendices 2 to 6 1.
- Appendix 14 14. The semiconductor device according to any one of appendices 1 to 13, wherein the maximum impurity concentration of the column region (38) is higher than the first concentration peak (CP1).
- the drift layer (33) has a third region (33C) provided at a position deeper than the second region (33B), 15.
- the semiconductor device (10) is having a main cell region (11) forming an IGBT and a diode cell region (14) forming a free wheel diode connected to the IGBT,
- the trench (35) is provided in both the main cell region (11) and the diode cell region (14),
- the column region (38) is provided at the bottom (35a) of the trench (35) formed in the main cell region (11) and is formed in the diode cell region (14). 16.
- the semiconductor device (10) is having a main cell region (11) forming an IGBT and a diode cell region (14) forming a free wheel diode connected to the IGBT,
- the trench (35) is provided in both the main cell region (11) and the diode cell region (14),
- the column region (38) is not located at the bottom (35a) of the trench (35) formed in the diode cell region (14), but the trench (38) formed in the main cell region (11).
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Abstract
Description
図1を参照して、半導体装置10の一実施形態の構成について説明する。
図1に示すように、本実施形態の半導体装置10は、トレンチゲート型IGBT(Insulated Gate Bipolar Transistor)である。この半導体装置10は、たとえば車載用インバータ装置においてスイッチング素子として用いられる。
エミッタ電極21は、IGBTのエミッタを構成する電極であり、半導体装置10のメイン電流が流れる電極である。エミッタ電極21は、装置主面10sに形成されている。エミッタ電極21のうちy方向の中央よりも装置側面10cの近くかつx方向の中央には、凹部21aが形成されている。凹部21aは、装置側面10cに向けて開口している。
次に、メインセル領域11のメインセル11Aの構成について説明する。図2は、メインセル領域11の一部および外周領域12の一部の断面構造の一例を示している。なお、図2では、便宜上、メインセル領域11における半導体装置10の構成要素の一部のハッチングを省略して示している。
半導体基板30は、基板裏面30rから基板表面30sに向けて順に、p+型のコレクタ層31、n型のバッファ層32、およびn-型のドリフト層33が積層された構造を有している。基板裏面30rには、コレクタ電極27が形成されている。コレクタ電極27は、基板裏面30rの略全面にわたり形成されている。コレクタ電極27のうち基板裏面30rとは反対側の面は、半導体装置10の装置裏面10rを構成している。
図3は、図2のメインセル領域11におけるメインセル11Aの一部を拡大した図である。図4は、図3のメインセル11Aにおいてz方向に延びる破線である第1直線L1および第2直線L2における不純物濃度の分布の一例を示すグラフである。第1直線L1は、x方向において隣り合うトレンチ35間の間に位置している。第2直線L2は、トレンチ35内に位置している。図4における実線のグラフG1は第1直線L1における不純物濃度の分布を示すグラフであり、図4における一点鎖線のグラフG2は第2直線L2における不純物濃度の分布を示すグラフである。図4では、横軸がドリフト層33の表面(基板表面30s)からの深さを示し、縦軸が不純物濃度を示している。以下の説明において、図3の半導体装置10の構成要素を参照して説明するものとする。
図5~図11を参照して、本実施形態の半導体装置10の製造方法について説明する。なお、以下では、メインセル領域11の製造方法について説明する。また、便宜上、図5~図11を用いて、1つの半導体装置10の製造方法として説明する。ここで、本実施形態の半導体装置10の製造方法は、1つの半導体装置10の製造に限られず、複数の半導体装置10の製造であってもよい。
この工程においては、不純物は、トレンチ835からz方向に対して傾斜した方向でドリフト層33に注入され、拡散される。一例では、z方向に対して7°傾斜した方向からトレンチ835を介してドリフト層33に注入され、拡散される。これにより、ドリフト層33に第1領域33A、第2領域33B、および第3領域33Cが形成される。第1領域33Aは、第1濃度ピークCP1を有する領域となる。第1領域33Aの不純物濃度は、たとえば1×1015cm-3よりも高くかつ1×1017cm-3よりも低くなる。第2領域33Bは、第1濃度ピークCP1よりも低い第2濃度ピークCP2を有する領域となる。第2領域33Bの不純物濃度は、たとえば1×1014cm-3よりも高くかつ2×1015cm-3以下となる。第3領域33Cは、トレンチ835よりも基板裏面に近い領域である。第3領域33Cの不純物濃度は、たとえば1×1014cm-3となる。
この工程においては、第2導電型(p型)の不純物が、メインセル領域11の全体に対してz方向に沿ってドリフト層33に注入される。これにより、x方向において隣り合うトレンチ835の間のドリフト層33にp型不純物が注入および拡散されることによってベース領域34が形成される。トレンチ835を介してトレンチ835の底部835aにp型不純物が注入および拡散されることによってカラム領域38が形成される。ベース領域34の不純物濃度は、たとえば1×1016cm-3以上1×1018cm-3以下となる。カラム領域38の不純物濃度は、たとえば1.0×1015cm-3以上5.0×1017cm-3以下となる。その後、犠牲酸化膜850を除去する。
絶縁膜841を形成する工程では、まず、半導体基板830が熱酸化されることによって各トレンチ835の内面を含む半導体基板830の表面全体に酸化膜が形成される。これにより、半導体基板830の基板表面830sに絶縁膜841が形成される。絶縁膜841は、絶縁膜41に対応する絶縁膜である。メインセル領域11(図2参照)の絶縁膜841は、ゲート絶縁膜であり、各トレンチ835の内面にも形成される。
まず、たとえばチタン(Ti)を用いたスパッタリングによって、中間絶縁膜42の表面42sおよび開口部843の内面に第1金属層を形成する。続いて、第1金属層上に窒化チタン(TiN)を用いたスパッタリングによって第2金属層を形成する。これにより、バリアメタル層21eが形成される。続いて、AlCuを用いたスパッタリングによって電極層821を形成する。電極層821は、z方向から視て中間絶縁膜42の全体にわたり形成されている。続いて、電極層821をエッチングすることによって、エミッタ電極21が形成される。
図3、図4、および図12~図18を参照して、本実施形態の作用について説明する。
図12は、実験例1の半導体装置10Xのメインセル領域11の断面構造を示している。図13は、実験例2の半導体装置10Yのメインセル領域11の断面構造を示している。図4における破線のグラフGRは、半導体装置10X,10Yの第1直線L1における不純物濃度の分布を示すグラフである。なお、本実施形態の半導体装置10は実験例3として扱う。
図15に示すように、実験例3は、ターンオフ時において同じ損失Eoffの大きさにおけるコレクタ-エミッタ間飽和電圧Vce(sat)が実験例1,2よりも低いことが分かる。つまり、実験例3は、ターンオフ時においてコレクタ-エミッタ間電圧Vceにおける損失Eoffが実験例1,2よりも低くなることが分かる。これにより、実験例3は、実験例1,2よりもターンオフ時における損失Eoffおよびコレクタ-エミッタ間飽和電圧Vce(sat)の双方を低減するように設計できる。
図16に示すように、実験例3は、同じコレクタ-エミッタ間飽和電圧Vce(sat)における損失Eonが実験例1よりも大きく、実験例2よりも小さい。これは、実験例2,3は、実験例1よりもメインセル11Aの個数が多くなることによってミラー容量が増加したことが原因であると考えられる。一方、実験例3は、トレンチ35の底部35aにカラム領域38が設けられているため、ミラー容量の増加が抑制される。これにより、実験例3は、実験例2よりも同じコレクタ-エミッタ間飽和電圧Vce(sat)における損失Eonが小さくなる。
本実施形態の半導体装置10によれば、以下の効果が得られる。
(1)半導体装置10は、第1導電型(n型)のドリフト層33と、ドリフト層33の表面の側に形成された第2導電型(p型)のベース領域34と、ベース領域34を貫通してドリフト層33に到達するように深さ方向(z方向)に延びたトレンチ35と、トレンチ35の内面に形成された絶縁膜41と、絶縁膜41に囲まれたゲートトレンチ22Aと、ドリフト層33におけるトレンチ35の底部35aの位置に設けられた第2導電型(p型)のカラム領域38と、を備えている。ドリフト層33は、第1濃度ピークCP1を有する第1領域33Aと、トレンチ35よりも深い位置であってカラム領域38に対応する位置に設けられ、第1濃度ピークCP1よりも低い第2濃度ピークCP2を有する第2領域33Bと、を有している。
この構成によれば、各トレンチ35の底部35aの電界集中を低減できるため、半導体装置10の高耐圧化を図ることができる。
この構成によれば、カラム領域38を形成する場合にトレンチ35の配列方向(x方向)にカラム領域38が広がることを抑制できる。これにより、トレンチ35の配列方向に隣り合うカラム領域38同士が接合することを抑制できる。
この構成によれば、カラム領域38を形成する場合にトレンチ35の配列方向(x方向)にカラム領域38が広がることを一層抑制できる。これにより、トレンチ35の配列方向に隣り合うカラム領域38同士が接合することを一層抑制できる。
この構成によれば、トレンチ35の底部35aの電界集中を一層低減できる。
この構成によれば、同一のチップサイズにおいてメインセル11Aの個数を増やすことができる。しかし、この場合、トレンチ35間の距離が短くなりやすく、カラム領域38同士が接合するおそれがある。
上記実施形態は本開示に関する半導体装置が取り得る形態の例示であり、その形態を制限することを意図していない。本開示に関する半導体装置は、上記実施形態に例示された形態とは異なる形態を取り得る。その一例は、上記各実施形態の構成の一部を置換、変更、もしくは省略した形態、または上記実施形態に新たな構成を付加した形態である。また、以下の各変更例は、技術的に矛盾しない限り、互いに組み合わせることができる。以下の各変更例において、上記実施形態に共通する部分については、上記実施形態と同一符号を付してその説明を省略する。
・上記実施形態では、半導体装置10をIGBTとして具体化したが、これに限られず、半導体装置10は、トレンチ型のSiCMOSFET(metal-oxide-semiconductor field-effect transistor)またはSiMOSFETであってもよい。この場合、MOSFETのソース電極は「駆動電極」に対応する。
上記実施形態および上記各変更例から把握できる技術的思想を以下に記載する。なお、各付記に記載された構成要素に対応する実施形態の構成要素の符号を括弧書きで示す。符号は、理解の補助のために例として示すものであり、各付記に記載された構成要素は、符号で示される構成要素に限定されるべきではない。
第1導電型のドリフト層(33)と、
前記ドリフト層(33)の表面(30s)の側に形成された第2導電型のボディ領域(34)と、
前記ボディ領域(34)を貫通して前記ドリフト層(33)に到達するように深さ方向(z方向)に延びたトレンチ(35)と、
前記トレンチ(35)の内面に形成された絶縁膜(41)と、
前記絶縁膜(41)に囲まれたゲート電極(21A)と、
前記ドリフト層(33)における前記トレンチ(35)の底部(35a)の位置に設けられた第2導電型のカラム領域(38)と、を備え、
前記ドリフト層(33)は、
第1濃度ピーク(CP1)を有する第1領域(33A)と、
前記トレンチ(35)よりも深い位置であって前記カラム領域(38)に対応する位置に設けられ、前記第1濃度ピーク(CP1)よりも低い第2濃度ピーク(CP2)を有する第2領域(33B)と、を有している
半導体装置(10)。
前記トレンチ(35)は、互いに離間して配列された状態で複数設けられており、
前記カラム領域(38)は、前記複数のトレンチ(35)に対応して複数設けられている
付記1に記載の半導体装置。
前記第1領域(33A)は、前記トレンチ(35)の配列方向(x方向)において隣り合う前記トレンチ(35)の間に設けられており、
前記第2領域(33B)は、前記トレンチ(35)の配列方向(x方向)において隣り合う前記カラム領域(38)の間に設けられている
付記2に記載の半導体装置。
前記第1領域(33A)は、前記ドリフト層(33)における前記ボディ領域(34)との界面(39A)付近に設けられている
付記3に記載の半導体装置。
前記第2領域(33B)は、前記カラム領域(38)に対応する位置として、前記トレンチ(35)の深さ方向(z方向)において前記カラム領域(38)と同じ位置に設けられた部分を有している
付記3または4に記載の半導体装置。
前記第2領域(33B)は、前記カラム領域(38)に対応する位置として、前記トレンチ(35)の深さ方向(z方向)において前記カラム領域(38)からずれた位置に設けられた部分を有している
付記3~5のいずれか1つに記載の半導体装置。
前記トレンチ(35)の配列方向(x方向)において隣り合うトレンチ(35)の間の距離(D)は、前記トレンチ(35)の幅寸法(Wt)以下である
付記2~6のいずれか1つに記載の半導体装置。
前記カラム領域(38)は、前記トレンチ(35)の底部(35a)の全体を覆うように形成されている
付記1~7のいずれか1つに記載の半導体装置。
前記カラム領域(38)は、前記ドリフト層(33)の厚さ方向(z方向)において前記ボディ領域(34)から離間した位置に設けられている
付記1~8のいずれか1つに記載の半導体装置。
前記カラム領域(38)は、電気的にフローティング状態である
付記9に記載の半導体装置。
前記カラム領域(38)は、前記ボディ領域(34)と繋がっている
付記1~8のいずれか1つに記載の半導体装置。
前記カラム領域(38)の不純物濃度は、前記ボディ領域(34)の不純物濃度よりも低い
付記1~11のいずれか1つに記載の半導体装置。
前記カラム領域(38)の不純物濃度の最大値は、前記第2濃度ピーク(CP2)よりも高い
付記1~12のいずれか1つに記載の半導体装置。
前記カラム領域(38)の不純物濃度の最大値は、前記第1濃度ピーク(CP1)よりも高い
付記1~13のいずれか1つに記載の半導体装置。
前記ドリフト層(33)は、前記第2領域(33B)よりも深い位置に設けられた第3領域(33C)を有し、
前記第2濃度ピーク(CP2)は、前記第3領域(33C)の不純物濃度よりも高い
付記1~14のいずれか1つに記載の半導体装置。
前記半導体装置(10)は、
IGBTを構成するメインセル領域(11)と、前記IGBTに接続される還流ダイオードを構成するダイオードセル領域(14)と、を有し、
前記トレンチ(35)は、前記メインセル領域(11)および前記ダイオードセル領域(14)の双方に設けられており、
前記カラム領域(38)は、前記メインセル領域(11)に形成されている前記トレンチ(35)の底部(35a)の位置に設けられているとともに、前記ダイオードセル領域(14)に形成されている前記トレンチ(35)の底部(35a)の位置に設けられている
付記1~15のいずれか1つに記載の半導体装置。
前記半導体装置(10)は、
IGBTを構成するメインセル領域(11)と、前記IGBTに接続される還流ダイオードを構成するダイオードセル領域(14)と、を有し、
前記トレンチ(35)は、前記メインセル領域(11)および前記ダイオードセル領域(14)の双方に設けられており、
前記カラム領域(38)は、前記ダイオードセル領域(14)に形成されている前記トレンチ(35)の底部(35a)の位置ではなく、前記メインセル領域(11)に形成されている前記トレンチ(35)の底部(35a)の位置に選択的に設けられている
付記1~15のいずれか1つに記載の半導体装置。
11…メインセル領域
14…ダイオードセル領域
22…ゲート電極
30s…基板表面(ドリフト層の表面)
33…ドリフト層
33A…第1領域
33B…第2領域
33C…第3領域
34…ベース領域(ボディ領域)
35…トレンチ
35a…底部
38…カラム領域
41…絶縁膜
39A…ドリフト層とベース領域との界面
D…トレンチの間の距離
Wt…トレンチの幅寸法
Claims (17)
- 第1導電型のドリフト層と、
前記ドリフト層の表面の側に形成された第2導電型のボディ領域と、
前記ボディ領域を貫通して前記ドリフト層に到達するように深さ方向に延びたトレンチと、
前記トレンチの内面に形成された絶縁膜と、
前記絶縁膜に囲まれたゲート電極と、
前記ドリフト層における前記トレンチの底部の位置に設けられた第2導電型のカラム領域と、
を備え、
前記ドリフト層は、
第1濃度ピークを有する第1領域と、
前記トレンチよりも深い位置であって前記カラム領域に対応する位置に設けられ、前記第1濃度ピークよりも低い第2濃度ピークを有する第2領域と、
を有している
半導体装置。 - 前記トレンチは、互いに離間して配列された状態で複数設けられており、
前記カラム領域は、前記複数のトレンチに対応して複数設けられている
請求項1に記載の半導体装置。 - 前記第1領域は、前記トレンチの配列方向において隣り合う前記トレンチの間に設けられており、
前記第2領域は、前記トレンチの配列方向において隣り合う前記カラム領域の間に設けられている
請求項2に記載の半導体装置。 - 前記第1領域は、前記ドリフト層における前記ボディ領域との界面付近に設けられている
請求項3に記載の半導体装置。 - 前記第2領域は、前記カラム領域に対応する位置として、前記トレンチの深さ方向において前記カラム領域と同じ位置に設けられた部分を有している
請求項3または4に記載の半導体装置。 - 前記第2領域は、前記カラム領域に対応する位置として、前記トレンチの深さ方向において前記カラム領域からずれた位置に設けられた部分を有している
請求項3~5のいずれか一項に記載の半導体装置。 - 前記トレンチの配列方向において隣り合うトレンチの間の距離は、前記トレンチの幅寸法以下である
請求項2~6のいずれか一項に記載の半導体装置。 - 前記カラム領域は、前記トレンチの底部の全体を覆うように形成されている
請求項1~7のいずれか一項に記載の半導体装置。 - 前記カラム領域は、前記ドリフト層の厚さ方向において前記ボディ領域から離間した位置に設けられている
請求項1~8のいずれか一項に記載の半導体装置。 - 前記カラム領域は、電気的にフローティング状態である
請求項9に記載の半導体装置。 - 前記カラム領域は、前記ボディ領域と繋がっている
請求項1~8のいずれか一項に記載の半導体装置。 - 前記カラム領域の不純物濃度は、前記ボディ領域の不純物濃度よりも低い
請求項1~11のいずれか一項に記載の半導体装置。 - 前記カラム領域の不純物濃度の最大値は、前記第2濃度ピークよりも高い
請求項1~12のいずれか一項に記載の半導体装置。 - 前記カラム領域の不純物濃度の最大値は、前記第1濃度ピークよりも高い
請求項1~13のいずれか一項に記載の半導体装置。 - 前記ドリフト層は、前記第2領域よりも深い位置に設けられた第3領域を有し、
前記第2濃度ピークは、前記第3領域の不純物濃度よりも高い
請求項1~14のいずれか一項に記載の半導体装置。 - 前記半導体装置は、
IGBTを構成するメインセル領域と、前記IGBTに接続される還流ダイオードを構成するダイオードセル領域と、を有し、
前記トレンチは、前記メインセル領域および前記ダイオードセル領域の双方に設けられており、
前記カラム領域は、前記メインセル領域に形成されている前記トレンチの底部の位置に設けられているとともに、前記ダイオードセル領域に形成されている前記トレンチの底部の位置に設けられている
請求項1~15のいずれか一項に記載の半導体装置。 - 前記半導体装置は、
IGBTを構成するメインセル領域と、前記IGBTに接続される還流ダイオードを構成するダイオードセル領域と、を有し、
前記トレンチは、前記メインセル領域および前記ダイオードセル領域の双方に設けられており、
前記カラム領域は、前記ダイオードセル領域に形成されている前記トレンチの底部の位置ではなく、前記メインセル領域に形成されている前記トレンチの底部の位置に選択的に設けられている
請求項1~15のいずれか一項に記載の半導体装置。
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WO2017187670A1 (ja) * | 2016-04-27 | 2017-11-02 | 三菱電機株式会社 | 半導体装置および電力変換装置 |
WO2018163593A1 (ja) * | 2017-03-06 | 2018-09-13 | 三菱電機株式会社 | 炭化珪素半導体装置、電力変換装置、炭化珪素半導体装置の製造方法、および電力変換装置の製造方法 |
WO2021014570A1 (ja) * | 2019-07-23 | 2021-01-28 | 三菱電機株式会社 | 炭化珪素半導体装置、電力変換装置および炭化珪素半導体装置の製造方法 |
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WO2017094339A1 (ja) * | 2015-12-03 | 2017-06-08 | 三菱電機株式会社 | 炭化珪素半導体装置 |
WO2017187670A1 (ja) * | 2016-04-27 | 2017-11-02 | 三菱電機株式会社 | 半導体装置および電力変換装置 |
WO2018163593A1 (ja) * | 2017-03-06 | 2018-09-13 | 三菱電機株式会社 | 炭化珪素半導体装置、電力変換装置、炭化珪素半導体装置の製造方法、および電力変換装置の製造方法 |
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