Semiconductor device

Abstract

To provide a semiconductor device that can obtain more suitable forward voltage of a body diode.SOLUTION: A semiconductor device 100 includes a first electrode 11, a first conductive part 21, a semiconductor part 30, a second conductive part 22, a gate electrode 13, and an insulating part 40. A direction from the first electrode to the first conductive part is along a first direction Z. The semiconductor part has a first conductivity type including first and second semiconductor regions 31 and 32. At least a part of the first semiconductor region exists between the first conductive part and the first electrode. The first conductive part is in Schottky contact with the first semiconductor region. A direction from the first conductive part to the second semiconductor region is along a second direction X that intersects with the first direction. The second conductive part is in Schottky contact with the second semiconductor region. At least a part of the second conductive part exists between the first conductive part and the second semiconductor region. At least a part of the second semiconductor region exists between the gate electrode and the second conductive part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to semiconductor devices.

Background Art

[0002] There are semiconductor devices including body diodes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide a semiconductor device capable of obtaining a more appropriate forward voltage of a body diode.

Means for Solving the Problems

[0005] According to an embodiment of the present invention, a semiconductor device includes a first electrode, a first conductive portion, a semiconductor portion, a second conductive portion, a gate electrode, and an insulating portion. The direction from the first electrode to the first conductive portion is along a first direction. The first conductive portion includes a metal, a metal oxide, or a metal nitride including at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru. The semiconductor portion is of a first conductivity type including a first semiconductor region and a second semiconductor region. At least a part of the first semiconductor region is located between the first conductive portion and the first electrode. The first conductive portion makes a Schottky contact with the first semiconductor region. The direction from the first conductive portion to the second semiconductor region is along a second direction intersecting the first direction. The second conductive portion makes a Schottky contact with the second semiconductor region. The second conductive portion includes at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co. At least a part of the second conductive portion is located between the first conductive portion and the second semiconductor region. At least a part of the second semiconductor region is located between the gate electrode and the second conductive portion. The insulating portion includes a first insulating region provided between the gate electrode and the second semiconductor region.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

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Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationships between the thicknesses and widths of the respective parts, the ratios of the sizes between the parts, etc. are not necessarily the same as those in reality. Even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In the present specification and each figure, the same reference numerals are given to the same elements as those described above with respect to the previously shown figures, and the detailed description will be omitted as appropriate.

[0008] FIG. 1 and FIG. 2 are schematic cross-sectional views illustrating a semiconductor device according to an embodiment. FIG. 2 shows an enlarged view of the periphery of the first conductive portion 21 in FIG. 1. As shown in FIG. 1, the semiconductor device 100 according to the embodiment includes a first electrode 11, a second electrode 20, a gate electrode 13, an insulating portion 40, and a semiconductor portion 30. The second electrode 20 includes at least a first conductive portion 21 and a second conductive portion 22. The second electrode 20 may further include a third conductive portion 23, a fourth conductive portion 24, a conductive layer 26, and a conductive layer 27.

[0009] The direction from the first electrode 11 to the first conductive portion 21 follows the first direction. In the description of the embodiment, the first direction is defined as the Z direction. The direction intersecting the first direction is defined as the second direction (X direction). The X direction may be a direction perpendicular to the Z direction. The direction intersecting the first direction and the second direction is defined as the third direction (Y direction). The Y direction may be a direction perpendicular to the Z direction and the X direction. For example, the Z direction is a direction perpendicular to the upper surface 11a in contact with the semiconductor portion 30 of the first electrode 11. For example, the surface 30s (main surface of the semiconductor substrate) of the semiconductor portion 30 extends along the X-Y plane perpendicular to the Z direction. The surface 30s is a surface located on the second electrode 20 side of the semiconductor portion 30 in the Z direction. In the Z direction, the positional relationship or direction from the first electrode 11 toward the second electrode 20 may be referred to as upward.

[0010] The direction from the first electrode 11 to the semiconductor portion 30 follows the first direction. The semiconductor portion 30 includes a first semiconductor region 31, a second semiconductor region 32, a third semiconductor region 33, a fourth semiconductor region 34, and a fifth semiconductor region 35. The semiconductor portion 30 (the first to fifth semiconductor regions) has a first conductivity type. In this example, the first conductivity type is n-type and the second conductivity type is p-type, but in the embodiment, the first conductivity type may be p-type and the second conductivity type may be n-type.

[0011] At least a part of the first semiconductor region 31 is located between the first conductive portion 21 and the first electrode 11. The direction from the first semiconductor region 31 to the first conductive portion 21 follows the Z direction.

[0012] At least a part of the second semiconductor region 32 is aligned with the first conductive portion 21 in the X direction. That is, the direction from the first conductive portion 21 to the second semiconductor region 32 follows the X direction. The second semiconductor region 32 may be separated from the first conductive portion 21 in the X direction.

[0013] For example, a trench T1 is provided on the surface 30s of the semiconductor portion 30. The trench T1 is a recess that is recessed downward (in the direction of the first electrode 11). The trench T1 extends, for example, in the Y direction. A plurality of trenches T1 may be provided at intervals in the X direction. The first semiconductor region 31 constitutes the bottom surface of the trench T1. The second semiconductor region 32 constitutes the side surface of the trench T1.

[0014] The second semiconductor region 32 may include a first region 32s and a second region 32c. The second region 32c is located between the first region 32s and the first electrode 11. The impurity concentration (atoms / cm 3 ) of the first conductivity type in the first region 32s is higher than the impurity concentration of the first conductivity type in the second region 32c.

[0015] The third semiconductor region 33 is located between the first electrode 11 and the first semiconductor region 31 in the Z direction. The fourth semiconductor region 34 is located between the first electrode 11 and the insulating portion 40 in the Z direction. The fifth semiconductor region 35 is located between the third semiconductor region 33 and the first electrode 11 in the Z direction and is aligned with the fourth semiconductor region 34 in the X direction. The fourth semiconductor region 34 and the fifth semiconductor region 35 are in contact with the first electrode 11. The semiconductor portion 30 is electrically connected to the first electrode 11 in the fourth semiconductor region 34 and the fifth semiconductor region 35.

[0016] The first conductive portion 21, the second conductive portion 22, and the third conductive portion 23 are provided in the trench T1. The second electrode 20 is electrically connected to the semiconductor portion 30 in the portion provided in the trench T1 (the first conductive portion 21, the second conductive portion 22, and the third conductive portion 23).

[0017] The first conductive portion 21 is in contact with the bottom of the trench T1. That is, the first conductive portion 21 is in contact with the first semiconductor region 31. The first conductive portion 21 is electrically connected to the first semiconductor region 31. The first conductive portion 21 is in Schottky contact with the first semiconductor region 31. The first conductive portion 21 does not have to be in contact with the side surface of the trench T1. That is, the first conductive portion 21 does not have to be in contact with the second semiconductor region 32 in the X direction. In this example, the first conductive portion 21 is a part of the conductive layer 25 (conductive film) included in the second electrode 20.

[0018] At least a part of the second conductive portion 22 is located between the first conductive portion 21 and the second semiconductor region 32. The position of the second conductive portion 22 in the X direction is between the position of the first conductive portion 21 in the X direction and the position of the second semiconductor region 32 in the X direction.

[0019] The second conductive portion 22 is in contact with the side surface of the trench T1 in the X direction. That is, the second conductive portion 22 is in contact with the second semiconductor region 32. The second conductive portion 22 is aligned with the second semiconductor region 32 in the X direction. In other words, the direction from the second conductive portion 22 to the second semiconductor region 32 (the first region 32s, the second region 32c) is along the X direction. The second conductive portion 22 is in Schottky contact with the second semiconductor region 32 (the second region 32c). Also, the second conductive portion 22 is in contact with the first conductive portion 21 in the X direction and is electrically connected to the first conductive portion 21.

[0020] The second conductive portion 22 is provided on a part of the first semiconductor region 31. That is, the said part of the first semiconductor region 31 is located between the second conductive portion 22 and the first electrode 11. The second conductive portion 22 is in contact with the bottom of the trench T1. That is, the second conductive portion 22 is in contact with the said part of the first semiconductor region 31. For example, the second conductive portion 22 is in Schottky contact with the said part of the first semiconductor region 31.

[0021] The third conductive part 23 is located above the second conductive part 22. That is, the second conductive part 22 is located between the third conductive part 23 and the first semiconductor region 31 in the Z direction. The direction from the second conductive part 22 to the third conductive part 23 is along the Z direction. The third conductive part 23 is in contact with the upper end of the second conductive part 22. The third conductive part 23 is electrically connected to the second conductive part 22.

[0022] The third conductive part 23 is in contact with the side surface of the trench T1. That is, the third conductive part 23 is in contact with the second semiconductor region 32. The third conductive part 23 is aligned with the second semiconductor region 32 in the X direction. In other words, the direction from the third conductive part 23 to the second semiconductor region 32 (the first region 32s) is along the X direction.

[0023] In this example, the third conductive part 23 is a part of the conductive layer 25. For example, the first conductive part 21 and the third conductive part 23 are formed of substantially the same material and are included in a continuous single conductive layer 25.

[0024] The direction from the second conductive part 22 to the gate electrode 13 is along the X direction. At least a part of the second semiconductor region 32 is located between the gate electrode 13 and the second conductive part 22.

[0025] As shown in FIG. 1, the semiconductor device 100 further includes a conductive part 14 (conductive region). The direction from the conductive part 14 to the third semiconductor region 33 is along the X direction. In this example, the direction from the conductive part 14 to the gate electrode 13 is along the Z direction. The conductive part 14 is provided between the gate electrode 13 and the first electrode 11. A fourth semiconductor region 34 is provided between the conductive part 14 and the first electrode 11.

[0026] The insulating part 40 is in contact with the gate electrode 13, the conductive part 14, and the semiconductor part 30. The insulating part 40 electrically insulates the gate electrode 13 from the semiconductor part 30. The insulating part 40 electrically insulates the conductive part 14 from the semiconductor part 30. The insulating part 40 electrically insulates the gate electrode 13 from the conductive part 14.

[0027] More specifically, the insulating portion 40 includes a first insulating region 41 provided between the second semiconductor region 32 and the gate electrode 13. The insulating portion 40 also includes a third insulating region 43 provided between the third semiconductor region 33 and the conductive portion 14. Further, the insulating portion 40 includes portions provided between the fourth semiconductor region 34 and the conductive portion 14, portions provided between the conductive portion 14 and the gate electrode 13, and portions provided between the gate electrode 13 and the conductive layer 25.

[0028] For example, as shown in FIG. 1, a trench T2 is provided in the surface 30s of the semiconductor portion 30. The trench T2 is a recessed portion recessed downward. The trench T2 extends, for example, in the Y direction. A plurality of trenches T2 may be provided at intervals in the X direction. In the X direction, the trenches T1 and T2 are arranged alternately. At least a part of the insulating portion 40 is provided in the trench T2. The gate electrode 13 and the conductive portion 14 are surrounded by the insulating portion 40 within the trench T2.

[0029] The insulating portion 40 has an end face 40s (upper surface) in the Z direction. The gate electrode 13 is located between the end face 40s and the first electrode 11. In this example, the end face 40s of the insulating portion 40 is located above the semiconductor portion 30. In other words, the position of the semiconductor portion 30 in the Z direction is between the position of the end face 40s of the insulating portion 40 in the Z direction and the position of the first electrode 11 in the Z direction.

[0030] The conductive layer 25 is provided on the insulating portion 40, the semiconductor portion 30, and the second conductive portion 22. In other words, the insulating portion 40, the semiconductor portion 30, and the second conductive portion 22 are located between the conductive layer 25 and the first electrode 11. The conductive layer 25 is in contact with the semiconductor portion 30 and the second conductive portion 22 and is electrically connected to the semiconductor portion 30 and the second conductive portion 22. The conductive layer 25 is in contact with the end face 40s of the insulating portion 40.

[0031] The conductive layer 26 is laminated on the conductive layer 25. In other words, the conductive layer 25 is located between the conductive layer 26 and the first electrode 11. The conductive layer 26 is in contact with the conductive layer 25 and is electrically connected to the conductive layer 25. A part of the conductive layer 26 is disposed in the trench T1. Another part of the conductive layer 26 is disposed above the insulating portion 40. That is, the direction from the insulating portion 40 to the said another part of the conductive layer 26 is along the Z direction.

[0032] The conductive layer 27 is laminated on the conductive layer 26. In other words, the conductive layer 26 is located between the conductive layer 27 and the first electrode 11. The conductive layer 27 is in contact with the conductive layer 26 and is electrically connected to the conductive layer 26.

[0033] The semiconductor device 100 is, for example, a MOSFET (Metal Oxide Silicon Field Effect Transistor). By controlling the potential of the gate electrode 13, the current flowing between the first electrode 11 and the second electrode 20 can be controlled. The first electrode 11 functions as, for example, a drain electrode. The second electrode 20 functions as, for example, a source electrode. The first region 32s of the second semiconductor region 32 functions as, for example, a source region. The second region 32c of the second semiconductor region 32 functions as, for example, a channel region. The first insulating region 41 functions as, for example, a gate insulating film.

[0034] For example, a Schottky barrier is formed at the interface between the second conductive portion 22 and the second semiconductor region 32 (second region 32c), and a depletion layer is formed in the second semiconductor region 32 (second region 32c). Depending on the potential of the gate electrode 13, the thickness of the Schottky barrier (distance in the X direction) is controlled, and the carrier concentration in the second semiconductor region 32 (second region 32c) is controlled. When the carrier concentration in the second semiconductor region 32 is low, substantially no current flows between the second electrode 20 and the first electrode 11 through the second semiconductor region 32. That is, an off state is obtained. By controlling the potential of the gate electrode 13, when the carrier concentration in the second semiconductor region 32 increases, current flows between the second electrode 20 and the first electrode 11 through the second semiconductor region 32. That is, an on state is obtained. For example, carriers flow between the second electrode 20 and the semiconductor portion 30 through a portion of the second electrode 20 that contacts the first region 32s (a part of the second conductive portion 22, the third conductive portion 23, and the fourth conductive portion 24).

[0035] Also, for example, a Schottky barrier is formed at the interface between the first conductive portion 21 (and the second conductive portion 22) and the first semiconductor region 31. The thickness of the Schottky barrier (distance in the Z direction) can be controlled by the potential of the gate electrode 13. When the Schottky barrier is thick, current does not easily flow. For example, an off state is obtained. By controlling the potential of the gate electrode 13, the Schottky barrier becomes thin and tunneling current easily flows. For example, an on state is obtained.

[0036] For example, the conductive portion 14 is electrically connected to the second electrode 20. Alternatively, the conductive portion 14 may be capable of being electrically connected to the second electrode 20. For example, as shown in FIG. 1, the semiconductor device 100 may have a wiring 14L that electrically connects the conductive portion 14 and the second electrode 20. The conductive portion 14 and the second electrode 20 may be electrically connected via wirings and terminals outside the semiconductor device 100.

[0037] The potential of the conductive portion 14 is set to the potential of the second electrode 20 (for example, the source potential). By providing the conductive portion 14, the electric field in the semiconductor portion 30 can be controlled. For example, the concentration of the local electric field can be suppressed. For example, high reliability can be easily obtained. The conductive portion 14 functions as a field plate, for example.

[0038] For example, there is a transistor of a reference example having an npn structure. In this case, the gate length becomes longer according to the width of the pn junction. On the other hand, in the embodiment, the semiconductor portion 30 is of the first conductivity type and may not include a region of the second conductivity type. That is, no pn junction is formed. Thereby, for example, it is easy to shorten the gate length. Therefore, it is easy to reduce the gate capacitance. Also, for example, it is easy to reduce the on-resistance. High-speed switching, suppression of turn-on loss, and suppression of turn-off loss can be realized. According to the embodiment, a semiconductor device capable of improving characteristics can be provided.

[0039] In the transistor of the reference example, a body diode is formed by the pn junction. Therefore, it may take a long time for recovery. On the other hand, in the embodiment, a Schottky barrier is formed at the interface between the first conductive portion 21 and the first semiconductor region 31. Thereby, a body diode is formed. Since the body diode is a Schottky barrier diode in this way, the recovery characteristics can be improved. The recovery can be speeded up. The forward voltage of the body diode can be lowered.

[0040] The first conductive portion 21 is a metal or a metal oxide or a metal nitride including at least one selected from the group consisting of Ti (titanium), Ta (tantalum), W (tungsten), Cr (chromium), and Ru (ruthenium), for example. The first conductive portion 21 includes a material having a relatively small work function, for example. That is, the first conductive portion 21 contains a first element. The first element is, for example, at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru. The first conductive portion 21 includes, for example, a simple metal composed of the first element (such as Ti, Ta, W, Cr, Ru, etc.). The first conductive portion 21 may include, for example, a compound containing the first element. For example, the first conductive portion 21 includes a nitride of the first element (such as titanium nitride, tantalum nitride, tungsten nitride, chromium nitride, ruthenium nitride, etc.). For example, the first conductive portion 21 includes an oxide of the first element (such as titanium oxide, tantalum oxide, tungsten oxide, chromium oxide, ruthenium oxide, etc.). Alternatively, the first conductive portion 21 may include an alloy containing the first element or a solid solution containing the first element.

[0041] The second conductive portion 22 includes, for example, at least one selected from the group consisting of Pt (platinum), Ni (nickel), Ir (iridium), Pd (palladium), Au (gold), and Co (cobalt). The first conductive portion 21 includes, for example, a material having a relatively large work function. That is, the second conductive portion 22 contains a second element. The second element is, for example, at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co. The second conductive portion 22 includes, for example, a simple metal composed of the second element (such as Pt, Ni, Ir, Pd, Au, Co, etc.). The second conductive portion 22 may include, for example, a compound, alloy, or solid solution containing the second element.

[0042] In the first semiconductor region 31, the first conductive portion 21 made of a material different from the second conductive portion 22 as described above is in contact. Thereby, the height of the Schottky barrier between the first conductive portion 21 and the semiconductor portion 30 can be controlled, and the forward voltage of the body diode can be controlled. According to the embodiment, a more appropriate forward voltage of the body diode can be obtained.

[0043] In this example (where the first conductivity type is n-type), the work function of the first conductive portion 21 may be lower than the work function of the second conductive portion 22. For example, the first conductive portion 21 is made of a first conductive material having a work function lower than that of the second conductive portion 22 (second conductive material). For example, the second conductive portion 22 is made of a second conductive material having a work function higher than that of the first conductive portion 21 (first conductive material). In this example, the first conductive portion 21 having a work function lower than that of the second conductive portion 22 contacts the bottom of the trench T1, whereby, for example, a low forward voltage of the body diode can be obtained.

[0044] The second conductive portion 22 is in contact with the second semiconductor region 32. Thereby, the height of the Schottky barrier between the second semiconductor region 32 and the second conductive portion 22 is controlled, and the threshold value of the transistor can be controlled. In this example (where the first conductivity type is n-type), the second conductive portion 22 having a work function higher than that of the first conductive portion 21 contacts the side surface of the trench T1, whereby, for example, it is possible to suppress the threshold value from becoming too low.

[0045] The third conductive portion 23 is, for example, a metal or a metal oxide or a metal nitride containing at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru. The third conductive portion 23 includes, for example, a material having a relatively small work function. That is, the third conductive portion 23 contains a third element. The third element is, for example, at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru. The third conductive portion 23 includes, for example, a simple metal (such as Ti, Ta, W, Cr, Ru, etc.) composed of the third element. Alternatively, the third conductive portion 23 may include, for example, a compound containing the third element. For example, the third conductive portion 23 includes a nitride of the third element (such as titanium nitride, tantalum nitride, tungsten nitride, chromium nitride, ruthenium nitride, etc.). Also, for example, the third conductive portion 23 includes an oxide of the third element (such as titanium oxide, tantalum oxide, tungsten oxide, chromium oxide, ruthenium oxide, etc.). Or, the third conductive portion 23 may include an alloy containing the third element or a solid solution containing the third element.

[0046] The third conductive portion 23 is connected above the second conductive portion 22. And a third conductive portion 23 made of a material different from that of the second conductive portion 22 as described above is in contact with the second semiconductor region 32. The contact resistance between the second electrode 20 and the semiconductor portion 30 can be controlled by the third conductive portion 23.

[0047] In this example (where the first conductivity type is n-type), the work function of the third conductive portion 23 may be lower than the work function of the second conductive portion 22. For example, the third conductive portion 23 is made of a third conductive material having a work function lower than that of the second conductive portion 22. For example, the third conductive portion 23 is made of the same material as that of the first conductive portion 21. The work function of the third conductive portion 23 may be the same as the work function of the first conductive portion 21. In this example, by the third conductive portion 23 having a work function lower than that of the second conductive portion 22 coming into contact with the second semiconductor region 32 (the first region 32s), for example, the contact resistance can be reduced.

[0048] The material of the conductive layer 25 may be the same as the material of the first conductive portion 21 or the material of the third conductive portion 23.

[0049] The fourth conductive portion 24 is provided on the second semiconductor region 32. That is, the second semiconductor region 32 is located between the fourth conductive portion 24 and the first electrode 11. The direction from the second semiconductor region 32 to the fourth conductive portion 24 is along the Z direction. The fourth conductive portion 24 is in contact with the second semiconductor region 32 (the first region 32s). The fourth conductive portion 24 may be electrically connected to the second semiconductor region 32 (the first region 32s). The fourth conductive portion 24 is located between the insulating portion 40 and the conductive layer 25 and is in contact with the insulating portion 40 and the conductive layer 25. The fourth conductive portion 24 may be electrically connected to the conductive layer 25.

[0050] The fourth conductive portion 24 includes, for example, at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co. The fourth conductive portion 24 includes, for example, a material having a relatively large work function. That is, the fourth conductive portion 24 contains a fourth element. The fourth element is, for example, at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co. The fourth conductive portion 24 includes, for example, a simple metal composed of the fourth element (such as Pt, Ni, Ir, Pd, Au, Co, etc.). The fourth conductive portion 24 may include, for example, a compound, alloy, or solid solution containing the fourth element.

[0051] In this example (where the first conductivity type is n-type), the work function of the fourth conductive portion 24 may be higher than the work function of the first conductive portion 21. For example, the fourth conductive portion 24 is made of a fourth conductive material having a work function higher than the work function of the first conductive portion 21. For example, the fourth conductive portion 24 is made of the same material as the material of the second conductive portion 22. The work function of the fourth conductive portion 24 may be the same as the work function of the second conductive portion 22.

[0052] As shown in FIG. 2, the first conductive portion 21 has an end portion 21u (lower end). Further, the second conductive portion 22 has a first end portion 22t (upper end) which is an end portion in the Z direction, and a first other end portion 22u (lower end). The first other end portion 22u (lower end) is aligned with the end portion 21u in the X direction. At least a part of the first other end portion 22u is located between the first end portion 22t and the first electrode 11.

[0053] The first semiconductor region 31 has a facing surface F1 facing the first conductive portion 21 and the second conductive portion 22. The facing surface F1 is located at the bottom of the trench T1 and is along, for example, the X - Y plane. The facing surface F1 is in contact with the lower ends (end portion 21u and the first other end portion 22u) of the first conductive portion 21 and the second conductive portion 22. The direction from the facing surface F1 to the gate electrode 13 is along the X direction.

[0054] The gate electrode 13 has a gate end 13t (upper end) which is an end in the Z direction, and a gate other end 13u (lower end). The gate other end 13u is located between the gate end 13t and the first electrode 11. The gate other end 13u (lower end) may be below the opposing surface F1. That is, the position of the opposing surface F1 in the Z direction may be between the position of the gate end 13t in the Z direction and the position of the gate other end 13u in the Z direction. Thereby, for example, it is easy to control the width of the depletion layer by the gate electrode 13.

[0055] For example, the length L1 along the Z direction in contact with the second semiconductor region 32 of the second conductive portion 22 is longer than the length L2 along the Z direction in contact with the second semiconductor region 32 of the third conductive portion 23. For example, the position of the gate end 13t (upper end) in the Z direction is between the position of the first end 22t of the second conductive portion 22 in the Z direction and the position of the first other end 22u in the Z direction. In this way, a margin is provided in which the second conductive portion 22 overlaps with the gate electrode 13 and the second semiconductor region 32 (second region 32c) in the X direction. Considering the process margin, it is easy to deplete the channel region of the second semiconductor region 32.

[0056] As shown in FIG. 2, for example, the length L3 may be longer than the length L2. The length L3 is the length along the Z direction between the gate end 13t and the first end 22t. Or, the length L2 may be longer than the length L3. When the length L2 is long, for example, it is easy to reduce the contact resistance.

[0057] For example, the length L4 in the X direction in contact with the first semiconductor region 31 of the second conductive portion 22 (for example, the width of the second conductive portion 22 in the X direction) may be longer than the length L5 in the X direction in contact with the first semiconductor region 31 of the first conductive portion 21. When the length L4 is long, for example, the depletion layer easily spreads in the semiconductor portion 30. For example, the breakdown voltage can be improved. Note that the length L5 may be longer than the length L4.

[0058] The semiconductor portion 30 may include at least one selected from the group consisting of silicon (Si), nitride semiconductors (such as GaN, etc.), silicon carbide (SiC), and oxide semiconductors (such as GaO). The semiconductor portion 30 is, for example, a silicon substrate. When the semiconductor portion 30 contains silicon, the n-type impurity includes, for example, at least one selected from the group consisting of phosphorus, arsenic, and antimony. The p-type impurity includes, for example, boron.

[0059] The first electrode 11 includes, for example, at least one selected from the group consisting of Al, Cu, Mo, W, Ta, Co, Ru, Ti, and Pt. The gate electrode 13 and the conductive portion 14 may include, for example, at least one of polysilicon and metal. The conductive layer 26 includes, for example, at least one selected from the group consisting of Ti and TiN. The conductive layer 27 includes, for example, at least one selected from the group consisting of Al, Cu, Mo, W, Ta, Co, Ru, Ti, and Pt.

[0060] A plurality of the first semiconductor region 31, the second semiconductor region 32, the first conductive portion 21, the second conductive portion 22, the third conductive portion 23, and the fourth conductive portion 24 may be provided. A plurality of trenches T1 arranged in the X direction are provided, and the first conductive portion 21, the second conductive portion 22, and the third conductive portion 23 are provided in each trench T1. The plurality of first conductive portions 21, the plurality of second conductive portions 22, and the plurality of third conductive portions 23 are included in one conductive layer 25.

[0061] A plurality of the gate electrode 13, the conductive portion 14, and the insulating portion 40 may be provided. A plurality of trenches T2 arranged in the X direction are provided, and the gate electrode 13, the conductive portion 14, and the insulating portion 40 are provided in each trench T2. One trench T1 is provided between two trenches T2. One first conductive portion 21, two second conductive portions 22, and two third conductive portions 23 are arranged in one trench T1.

[0062] That is, as shown in FIG. 1, between one gate electrode 13 and another gate electrode 13 (gate electrode 13b), at least a part of one second semiconductor region 32 and at least a part of another second semiconductor region 32 (semiconductor region 32b) are located. The side surfaces of one second semiconductor region 32 and the side surfaces of another second semiconductor region 32 are two side surfaces of the trench T1 facing each other.

[0063] Between one second semiconductor region 32 and another second semiconductor region 32, one second conductive part 22 and another second conductive part 22 (conductive part 22b) are located. Also, between one second semiconductor region 32 and another second semiconductor region 32, one third conductive part 23 and another third conductive part 23 (conductive part 23b) are located. One second conductive part 22 and one third conductive part 23 are in contact with the side surface of one second semiconductor region 32. Another second conductive part 22 and another third conductive part 23 are in contact with the side surface of another second semiconductor region 32.

[0064] One first conductive part 21 is arranged between one second conductive part 22 and another second conductive part 22. One first conductive part 21 is in contact with one second conductive part 22 and another second conductive part 22. One first conductive part 21, one second conductive part 22, and another second conductive part 22 are in contact with the bottom of one trench T1 (one first semiconductor region 31).

[0065] One fourth conductive part 24 is provided on one second semiconductor region 32, and another fourth conductive part (conductive part 24b) is provided on another second semiconductor region 32.

[0066] FIGS. 3(a), 3(b), 4(a), and 4(b) are schematic cross-sectional views illustrating a method of manufacturing a semiconductor device according to an embodiment. These figures illustrate a part of the manufacturing process of the semiconductor device 100. As shown in FIG. 3(a), a trench T2 is provided on the surface 30s of the semiconductor part 30. The trench T2 is filled with an insulating part 40, a conductive part 14, and a gate electrode 13. Also, a trench T1 is provided on the surface 30s of the semiconductor part 30. Thereby, the first semiconductor region 31 and the second semiconductor region 32 are formed.

[0067] As shown in FIG. 3(b), a conductive film 22f that becomes the second conductive portion 22 and the fourth conductive portion 24 is formed on the semiconductor portion 30 and the insulating portion 40. The conductive film 22f is in contact with the end face 40s of the insulating portion 40, the side surface and the upper end of the second semiconductor region 32, and the first semiconductor region 31.

[0068] As shown in FIG. 4(a), a part of the conductive film 22f is removed, for example, by reactive ion etching. Thereby, the second conductive portion 22 and the fourth conductive portion 24 are formed, and the end face 40s of the insulating portion 40, the side surface of the first region 32s of the second semiconductor region 32, and a part of the first semiconductor region 31 are exposed.

[0069] As shown in FIG. 4(b), a continuous conductive layer 25 is formed on the first semiconductor region 31, the second conductive portion 22, the fourth conductive portion 24, and the insulating portion 40. The conductive layer 25 is in contact with the first semiconductor region 31 and the second semiconductor region 32 (first region 32s) exposed in FIG. 4(a). Thereby, the first conductive portion 21 and the third conductive portion 23 are formed. The conductive layer 25 covers the end face 40s of the insulating portion 40 and is in contact with the end face 40s.

[0070] Thus, the first conductive portion 21 and the third conductive portion 23 are included in the conductive layer 25 that covers the second conductive portion 22, the fourth conductive portion 24, and the insulating portion 40. By forming the conductive layer 25 so as to cover the second conductive portion 22, the first conductive portion 21 and the third conductive portion 23 can be formed.

[0071] FIGS. 5 and 6 are schematic cross-sectional views illustrating a semiconductor device according to an embodiment. FIG. 6 shows the periphery of the first conductive portion 21 in FIG. 5 in an enlarged manner. In the semiconductor device 101 shown in FIGS. 5 and 6, the fourth conductive portion 24 is not provided on the second semiconductor region 32, and the insulating portion 40 includes a second insulating region 42.

[0072] The second insulating region 42 is located above the second semiconductor region 32. In other words, the second semiconductor region 32 is located between the second insulating region 42 and the first electrode 11. The direction from the second semiconductor region 32 to the second insulating region 42 is along the Z direction.

[0073] For example, as shown in FIG. 6, the second semiconductor region 32 has an upper surface 32f (upper end). The upper surface 32f faces, for example, the Z direction and is along the X-Y plane. The second insulating region 42 is in contact with the upper surface 32f of the second semiconductor region 32. The entire upper surface 32f may be covered by the second insulating region 42. The upper surface 32f does not have to be in contact with the second electrode 20. A part of the conductive layer 25 is provided on the second insulating region 42 and is in contact with the second insulating region 42.

[0074] For other aspects, the same explanations as those for the semiconductor device 100 described above can be applied to the configuration of the semiconductor device 101 shown in FIGS. 5 and 6. Also in the semiconductor device 101, similar to the semiconductor device 100, a more appropriate forward voltage of the body diode can be obtained. For example, the forward voltage can be reduced. Also, the contact resistance between the second electrode 20 and the semiconductor part 30 can be reduced.

[0075] When a fourth conductive part 24 in contact with the upper surface of the second semiconductor region 32 is provided as in the semiconductor device 100 shown in FIG. 1 etc., a path for carriers to flow is formed between the fourth conductive part 24 and the semiconductor part 30 through the upper surface of the second semiconductor region 32. At this time, for example, contact resistance occurs between the upper surface of the second semiconductor region 32 and the fourth conductive part 24. For example, the fourth conductive part 24 has a high work function and a high contact resistance occurs. On the other hand, in the semiconductor device 101 shown in FIGS. 5 etc., the second insulating region 42 is provided, and the contact between the upper surface 32f of the second semiconductor region 32 and the second electrode 20 is suppressed. The flow of carriers through the upper surface 32f of the second semiconductor region 32 is suppressed, and it is easy to adjust the contact. For example, the contact resistance can be reduced.

[0076] Figs. 7(a), 7(b), 8(a) and 8(b) are schematic cross-sectional views illustrating a method for manufacturing a semiconductor device according to an embodiment. These figures illustrate a part of the manufacturing process of the semiconductor device 101. As shown in Fig. 7(a), a trench T2 is provided on the surface 30s of the semiconductor portion 30. An insulating portion 40, a conductive portion 14, and a gate electrode 13 are embedded in the trench T2. A part of the insulating portion 40 (a portion that becomes the second insulating region 42) is provided over a part of the semiconductor portion 30 (a portion that becomes the second semiconductor region 32). Also, a trench T1 is provided on the surface 30s of the semiconductor portion 30. Thereby, a first semiconductor region 31 and a second semiconductor region 32 are formed. Also, a second insulating region 42 located over the second semiconductor region 32 is formed.

[0077] As shown in Fig. 7(b), a conductive film 22f that becomes a second conductive portion 22 and a fourth conductive portion 24 is formed over the semiconductor portion 30 and the insulating portion 40. The conductive film 22f is in contact with the end face 40s of the insulating portion 40, the second insulating region 42, the side surfaces of the second semiconductor region 32, and the first semiconductor region 31.

[0078] As shown in Fig. 8(a), a part of the conductive film 22f is removed, for example, by reactive ion etching. Thereby, the second conductive portion 22 is formed, and the end face 40s of the insulating portion 40, the second insulating region 42, the side surfaces of the first region 32s of the second semiconductor region 32, and a part of the first semiconductor region 31 are exposed.

[0079] As shown in Fig. 8(b), a continuous conductive layer 25 is formed over the first semiconductor region 31, the second conductive portion 22, and the insulating portion 40. The conductive layer 25 is in contact with the first semiconductor region 31 and the second semiconductor region 32 (the first region 32s) exposed in Fig. 8(a). Thereby, a first conductive portion 21 and a third conductive portion 23 are formed. The conductive layer 25 covers the end face 40s of the insulating portion 40 and the second insulating region 42 and is in contact with the end face 40s and the second insulating region 42.

[0080] Thus, the first conductive part 21 and the third conductive part 23 are included in the conductive layer 25 that covers the second conductive part 22 and the second insulating region 42. By forming the conductive layer 25 so as to cover the second conductive part 22, the first conductive part 21 and the third conductive part 23 can be formed.

[0081] The embodiment may include the following configurations (for example, technical solutions). (Configuration 1) A first electrode, A first conductive part, wherein the direction from the first electrode to the first conductive part is along a first direction and includes at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru, and the first conductive part includes a metal, a metal oxide, or a metal nitride, A first conductive-type semiconductor part including a first semiconductor region and a second semiconductor region, wherein at least a part of the first semiconductor region is located between the first conductive part and the first electrode, the first conductive part forms a Schottky contact with the first semiconductor region, and the direction from the first conductive part to the second semiconductor region is along a second direction that intersects the first direction, A second conductive part that forms a Schottky contact with the second semiconductor region and includes at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co, and at least a part of the second conductive part is located between the first conductive part and the second semiconductor region, A gate electrode, wherein at least a part of the second semiconductor region is located between the gate electrode and the second conductive part, An insulating part including a first insulating region provided between the gate electrode and the second semiconductor region, A semiconductor device including the above. (Configuration 2) Further including a third conductive part that is in contact with the second semiconductor region and includes at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru, and the third conductive part includes a metal, a metal oxide, or a metal nitride, The semiconductor device according to Configuration 1, wherein the second conductive part is located between the third conductive part and the first semiconductor region. (Configuration 3) The second semiconductor region includes a first region and a second region located between the first region and the first electrode. The concentration of impurities of the first conductivity type in the first region is higher than the concentration of impurities of the first conductivity type in the second region. The third conductive portion is in contact with the first region, and the semiconductor device according to Configuration 2. (Configuration 4) The length of the second conductive portion along the first direction in contact with the second semiconductor region is longer than the length of the third conductive portion along the first direction in contact with the second semiconductor region, and the semiconductor device according to Configuration 2 or 3. (Configuration 5) The second conductive portion includes a first end portion and a first other end portion. The first other end portion is located between the first end portion and the first electrode in the first direction. The gate electrode includes a gate end portion and a gate other end portion. The gate other end portion is located between the gate end portion and the first electrode in the first direction. The position of the gate end portion in the first direction is between the position of the first end portion in the first direction and the position of the first other end portion in the first direction, and the semiconductor device according to Configuration 4. (Configuration 6) The first conductive portion and the third conductive portion are included in a conductive layer covering the second conductive portion, and the semiconductor device according to any one of Configurations 2 to 5. (Configuration 7) The conductive layer is in contact with the end surface of the insulating portion in the first direction, and the semiconductor device according to Configuration 6. (Configuration 8) The semiconductor device further includes a fourth conductive portion including at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co. The second semiconductor region is located between the fourth conductive portion and the first electrode and is in contact with the fourth conductive portion, and the semiconductor device according to any one of Configurations 1 to 5. (Configuration 9) The first conductive portion is included in a conductive layer covering the second conductive portion and the fourth conductive portion, and the semiconductor device according to Configuration 8. (Configuration 10) The insulating portion further includes a second insulating region, The second semiconductor region is located between the second insulating region and the first electrode and is in contact with the second insulating region. The semiconductor device according to any one of Configurations 1 to 5. (Configuration 11) The first conductive portion is included in a conductive layer covering the second conductive portion and the second insulating region. The semiconductor device according to Configuration 10. (Configuration 12) The work function of the first conductive portion is lower than the work function of the second conductive portion. The semiconductor device according to any one of Configurations 1 to 11. (Configuration 13) The work function of the third conductive portion is lower than the work function of the second conductive portion. The semiconductor device according to any one of Configurations 2 to 7. (Configuration 14) The work function of the fourth conductive portion is higher than the work function of the first conductive portion. The semiconductor device according to Configuration 8 or 9. (Configuration 15) A part of the first semiconductor region is located between the second conductive portion and the first electrode, The second conductive portion is in contact with the part of the first semiconductor region. The semiconductor device according to any one of Configurations 1 to 14. (Configuration 16) The length of the second conductive portion in the second direction in contact with the first semiconductor region is longer than the length of the first conductive portion in the second direction in contact with the first semiconductor region. The semiconductor device according to Configuration 15. (Configuration 17) Further includes a conductive region, The semiconductor portion includes a third semiconductor region located between the first semiconductor region and the first electrode, The direction from the conductive region to the third semiconductor region is along the second direction, The insulating portion includes a third insulating region provided between the third semiconductor region and the conductive region. The semiconductor device according to any one of Configurations 1 to 16. (Configuration 18) The first semiconductor region has a facing surface facing the first conductive portion, In the semiconductor device according to any one of Configurations 1 to 17, the direction from the opposing surface to the gate electrode is along the second direction. (Configuration 19) A plurality of the gate electrodes, the second semiconductor regions, and the second conductive portions are provided respectively. Between one of the gate electrodes and another one of the gate electrodes, at least a part of one of the second semiconductor regions and at least a part of another one of the second semiconductor regions are located. Between one of the second semiconductor regions and another one of the second semiconductor regions, one of the second conductive portions and another one of the second conductive portions are located. In the semiconductor device according to any one of Configurations 1 to 18, the first conductive portion is located between one of the second conductive portions and another one of the second conductive portions.

[0082] In an embodiment, information regarding the shape of a semiconductor region, etc. can be obtained by, for example, electron microscope observation. Information regarding the material and the impurity concentration in the semiconductor region can be obtained by, for example, EDX (Energy Dispersive X-ray Spectroscopy), or SIMS (Secondary Ion Mass Spectrometry).

[0083] According to an embodiment, a semiconductor device capable of obtaining a more appropriate forward voltage of a body diode can be provided.

[0084] In this specification, the "nitride semiconductor" means B x In y Al z Ga 1-x-y-z It includes semiconductors of all compositions in which the composition ratios x, y, and z are changed within their respective ranges in the chemical formula N(0≦x≦1, 0≦y≦1, 0≦z≦1, x + y + z≦1). Further, in the above chemical formula, it also includes those further containing group V elements other than N (nitrogen), those further containing various elements added to control various physical properties such as conductivity type, and those further containing various elements contained unintentionally, and are included in the "nitride semiconductor".

[0085] In the present specification, "electrically connected" includes not only the case of being connected by direct contact but also the case of being connected via other conductive members or the like. In the present specification, "vertical" includes not only strict verticality but also, for example, variations in the manufacturing process, etc., and it suffices to be substantially vertical.

[0086] As described above, the embodiments of the present invention have been explained with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding the specific configuration of each element included in the semiconductor device, the present invention can be similarly implemented by appropriately selecting from the range known to those skilled in the art, and as long as the same effects can be obtained, it is included in the scope of the present invention.

[0087] Those obtained by combining any two or more elements of each specific example within a technically possible range are also included in the scope of the present invention as long as they include the gist of the present invention.

[0088] In addition, based on the semiconductor device described above as an embodiment of the present invention, all semiconductor devices that can be appropriately designed and modified by those skilled in the art also belong to the scope of the present invention as long as they include the gist of the present invention.

[0089] In addition, within the scope of the idea of the present invention, those skilled in the art can conceive of various modification examples and correction examples, and it is understood that those modification examples and correction examples also belong to the scope of the present invention.

[0090] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0091] 11: First electrode 11a: Upper surface 13: Gate electrode 13b: Gate electrode 13t: Gate end 13u: Other end of gate 14: Conductive part 14L: Wiring 20: Second electrode 21: First conductive part 21u: End 22: Second conductive part 22b: Conductive part 22f: Conductive film 22t: First end 22u: First other end 23: Third conductive part 23b: Conductive part 24: Fourth conductive part 24b: Conductive part 25, 26, 27: Conductive layer 30: Semiconductor part 30s: Surface 31: First semiconductor region 32: Second semiconductor region 32b: Semiconductor region 32c: Second region 32f: Upper surface 32s: First region 33: Third semiconductor region 34: Fourth semiconductor region 35: Fifth semiconductor region 40: Insulating part 40s: End face 41: First insulating region 42: Second insulating region 43: Third insulating region 100, 101: Semiconductor device F1: Opposing surface L1~L5: Length T1, T2: Trench

Claims

1. a first electrode; a first conductive part, wherein the direction from the first electrode to the first conductive part is along a first direction and includes at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru, and is a metal, metal oxide, or metal nitride-containing first conductive part; a first conductive-type semiconductor part including a first semiconductor region and a second semiconductor region, wherein at least a part of the first semiconductor region is located between the first conductive part and the first electrode, the first conductive part makes a Schottky contact with the first semiconductor region, and the direction from the first conductive part to the second semiconductor region is along a second direction intersecting the first direction; a second conductive part making a Schottky contact with the second semiconductor region and including at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co, wherein at least a part of the second conductive part is located between the first conductive part and the second semiconductor region; a gate electrode, wherein at least a part of the second semiconductor region is located between the gate electrode and the second conductive part; an insulating part including a first insulating region provided between the gate electrode and the second semiconductor region; a semiconductor device comprising the above.

2. further comprising a third conductive part in contact with the second semiconductor region and including at least one selected from the group consisting of Ti, Ta, W, Cr, and Ru, and being a metal, metal oxide, or metal nitride-containing third conductive part; The semiconductor device according to claim 1, wherein the second conductive part is located between the third conductive part and the first semiconductor region.

3. The second semiconductor region includes a first region and a second region located between the first region and the first electrode; the concentration of the first conductive-type impurity in the first region is higher than the concentration of the first conductive-type impurity in the second region; The semiconductor device according to claim 2, wherein the third conductive part is in contact with the first region.

4. The semiconductor device according to claim 2 or 3, wherein the length of the second conductive part along the first direction in contact with the second semiconductor region is longer than the length of the third conductive part along the first direction in contact with the second semiconductor region.

5. The second conductive part includes a first end portion and a first other end portion; the first other end portion is located between the first end portion and the first electrode in the first direction; the gate electrode includes a gate end portion and a gate other end portion; The other end of the gate is located between the end of the gate and the first electrode in the first direction. The semiconductor device according to claim 4, wherein the position of the end of the gate in the first direction is between the position of the first end in the first direction and the position of the first other end in the first direction. **Claim 6** The semiconductor device according to claim 2 or 3, wherein the first conductive portion and the third conductive portion are included in a conductive layer covering the second conductive portion. **Claim 7** The semiconductor device according to claim 6, wherein the conductive layer is in contact with an end surface of the insulating portion in the first direction. **Claim 8** Further comprising a fourth conductive portion including at least one selected from the group consisting of Pt, Ni, Ir, Pd, Au, and Co. The semiconductor device according to any one of claims 1 to 3, wherein the second semiconductor region is located between the fourth conductive portion and the first electrode and is in contact with the fourth conductive portion. **Claim 9** The semiconductor device according to claim 8, wherein the first conductive portion is included in a conductive layer covering the second conductive portion and the fourth conductive portion. **Claim 10** The insulating portion further includes a second insulating region. The semiconductor device according to any one of claims 1 to 3, wherein the second semiconductor region is located between the second insulating region and the first electrode and is in contact with the second insulating region. **Claim 11** The semiconductor device according to claim 10, wherein the first conductive portion is included in a conductive layer covering the second conductive portion and the second insulating region. **Claim 12** The semiconductor device according to any one of claims 1 to 3, wherein the work function of the first conductive portion is lower than the work function of the second conductive portion. **Claim 13** The semiconductor device according to claim 2 or 3, wherein the work function of the third conductive portion is lower than the work function of the second conductive portion. **Claim 14** The semiconductor device according to claim 8, wherein the work function of the fourth conductive portion is higher than the work function of the first conductive portion. **Claim 15** A part of the first semiconductor region is located between the second conductive portion and the first electrode. The semiconductor device according to any one of claims 1 to 3, wherein the second conductive portion is in contact with the part of the first semiconductor region. **Claim 16** The semiconductor device according to claim 15, wherein the length of the second conductive portion in the second direction in contact with the first semiconductor region is longer than the length of the first conductive portion in the second direction in contact with the first semiconductor region. **Claim 17** Further comprising a conductive region. The semiconductor portion includes a third semiconductor region located between the first semiconductor region and the first electrode. The direction from the conductive region toward the third semiconductor region is along the second direction. The semiconductor device according to any one of claims 1 to 3, wherein the insulating portion includes a third insulating region provided between the third semiconductor region and the conductive region.

18. The first semiconductor region has a facing surface facing the first conductive portion. The semiconductor device according to any one of claims 1 to 3, wherein the direction from the facing surface to the gate electrode is along the second direction.

19. A plurality of the gate electrodes, the second semiconductor regions, and the second conductive portions are provided respectively. At least a part of one of the second semiconductor regions and at least a part of another one of the second semiconductor regions are located between one of the gate electrodes and another one of the gate electrodes. One of the second conductive portions and another one of the second conductive portions are located between one of the second semiconductor regions and another one of the second semiconductor regions. The semiconductor device according to any one of claims 1 to 3, wherein the first conductive portion is located between one of the second conductive portions and another one of the second conductive portions.

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