Semiconductor device

Abstract

Embodiments provide a nitride semiconductor device having a current sensing function. The semiconductor device of the embodiments includes a first nitride semiconductor layer, a second nitride semiconductor layer provided on the first nitride semiconductor layer, a drain electrode having a plurality of drain fingers, a source electrode having a plurality of source fingers and a Kelvin source portion electrically connected to the source fingers, a sensing electrode between the drain fingers and the Kelvin source portion, and a gate electrode between the drain fingers and the source fingers and between the drain fingers and the sensing electrode. The sensing electrode and the Kelvin source portion are electrically connected via a sensing resistance based on a spacing of the sensing electrode and the Kelvin source portion in a second direction.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2022-36260 (filed on March 9, 2022). This application incorporates the entire contents of that basic application by reference. Technical Field

[0002] The implementation involves a semiconductor device. Background Technology

[0003] Currently, GaN power devices with overcurrent protection and other functions are limited to cascode / cas-source types that monitor current using silicon MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors). To monitor the current in normally closed GaN devices, it is necessary to fabricate current sensing elements using GaN devices. Summary of the Invention

[0004] The implementation provides a semiconductor device with current sensing functionality.

[0005] According to an embodiment, a semiconductor device includes: a first nitride semiconductor layer; a second nitride semiconductor layer disposed on the first nitride semiconductor layer and having a wider bandgap than the first nitride semiconductor layer; a drain electrode having a plurality of drain fingers extending along a first direction; a source electrode having a plurality of source fingers extending along the first direction and a Kelvin source portion extending along the first direction and electrically connected to the source fingers; a sensing electrode located between the adjacent drain fingers and the Kelvin source portions in a second direction intersecting the first direction and extending along the first direction; and a gate electrode located between the adjacent drain fingers and the source fingers in the second direction and between the adjacent drain fingers and the sensing electrode in the second direction and extending along the first direction, wherein the sensing electrode and the Kelvin source portion are electrically connected via a sensing resistor based on the spacing between the sensing electrode and the Kelvin source portion in the second direction. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating an example of a planar layout of a semiconductor device according to an implementation method.

[0007] Figure 2 This is a schematic cross-sectional perspective view of the first chip of the semiconductor device according to the embodiment.

[0008] Figure 3 yes Figure 2 The equivalent circuit diagram of the first chip is shown.

[0009] Figure 4 This is a schematic cross-sectional perspective view illustrating other examples of the first chip in the implementation method.

[0010] Figure 5 yes Figure 4 The equivalent circuit diagram of the first chip is shown. Detailed Implementation

[0011] Hereinafter, the embodiments will be described with reference to the accompanying drawings. Furthermore, in each of the drawings, the same reference numerals are used to label the same components.

[0012] like Figure 1 As shown, the semiconductor device 1 of the embodiment includes a first chip 10A and a second chip 20. For example, the first chip 10A and the second chip 20 are mounted on a wiring substrate in a packaged state. Alternatively, the first chip 10A and the second chip 20 may be mounted in separate packages and mounted on a wiring substrate.

[0013] The first chip 10A is, for example, a normally closed nitride semiconductor HEMT (High Electron Mobility Transistor) that is cut off when there is no input signal in the gate. For example, Figure 2 As shown, the first chip 10A has a MOS structure in the portion where a portion of the second nitride semiconductor layer 12 is removed. An insulating film 13 is provided between the gate electrode 50 and the second nitride semiconductor layer 12, and between the gate electrode 50 and the first nitride semiconductor layer 11. Alternatively, the first chip 10A may also have a structure in which a p-type nitride semiconductor layer is included below the gate electrode.

[0014] like Figure 2 As shown, the first chip 10A has a first nitride semiconductor layer 11 and a second nitride semiconductor layer 12. The first nitride semiconductor layer 11 is disposed on the substrate 100, and the second nitride semiconductor layer 12 is disposed on the first nitride semiconductor layer 11. The first nitride semiconductor layer 11 and the second nitride semiconductor layer 12 form a heterojunction. Alternatively, the first nitride semiconductor layer 11 can be disposed on the substrate 100 with a buffer layer in between.

[0015] The band gap of the second nitride semiconductor layer 12 is wider than that of the first nitride semiconductor layer 11. For example, the first nitride semiconductor layer 11 is a GaN layer, and the second nitride semiconductor layer 12 is an AlGaN layer. A two-dimensional electron gas 15 is distributed near the interface between the first nitride semiconductor layer 11 and the second nitride semiconductor layer 12 in the first nitride semiconductor layer 11. An insulating film 13 is provided on the second nitride semiconductor layer 12. For example, a silicon oxide film or a silicon nitride film can be used as the insulating film 13.

[0016] The first chip 10A has a drain electrode 30, a source electrode 40, a plurality of gate electrodes 50, and a sensing electrode 60. The drain electrode 30, the source electrode 40, the gate electrodes 50, and the sensing electrode 60 are provided on the second nitride semiconductor layer 12.

[0017] In Figure 1 and Figure 2 , two mutually orthogonal directions are defined as the first direction Y and the second direction X. In Figure 2 , the direction orthogonal to the first direction Y and the second direction X and directed from the first nitride semiconductor layer 11 toward the second nitride semiconductor layer 12 is defined as the third direction Z.

[0018] As Figure 1 shown, the drain electrode 30 has a drain power supply portion 31 extending along the second direction X and a plurality of drain fingers 32 extending from the drain power supply portion 31 along the first direction Y. As Figure 2 shown, the drain fingers 32 are in contact with the second nitride semiconductor layer 12.

[0019] As Figure 1 shown, the source electrode 40 has a source power supply portion 41 extending along the second direction X, a plurality of source fingers 42 extending from the source power supply portion 41 along the first direction Y, and a Kelvin source portion (Japanese: ケルビンソース部) 43 extending from the source power supply portion 41 along the first direction Y. The source fingers 42 and the Kelvin source portion 43 are electrically connected to each other through the source power supply portion 41. As Figure 2 shown, the source fingers 42 and the Kelvin source portion 43 are in contact with the second nitride semiconductor layer 12.

[0020] The sensing electrode 60 is located between the drain fingers 32 and the Kelvin source portion 43 adjacent to each other in the second direction X and extends along the first direction Y. The sensing electrode 60 is in contact with the second nitride semiconductor layer 12.

[0021] The gate electrodes 50 are located between the drain fingers 32 and the source fingers 42 adjacent to each other in the second direction X and between the drain fingers 32 and the sensing electrode 60 adjacent to each other in the second direction X, and extend along the first direction Y. The gate electrodes 50 are located on the insulating film 13 and are not in contact with the second nitride semiconductor layer 12. However, in the case of a structure including a p-type nitride semiconductor layer under the gate electrodes 50, the gate electrodes 50 are in contact with the p-type nitride semiconductor layer.

[0022] The first chip 10A has a plurality of main elements 91 and at least one sensing element 92. The substrate 100, the first nitride semiconductor layer 11, the second nitride semiconductor layer 12, the insulating film 13, and the two-dimensional electron gas 15 are provided commonly for the main elements 91 and the sensing elements 92.

[0023] The main element 91 includes a drain finger 32 and a source finger 42 that are adjacent in the second direction. Furthermore, the main element 91 includes a gate electrode 50 located between the drain finger 32 and the source finger 42 that are adjacent in the second direction.

[0024] The sensing element 92 includes a sensing electrode 60, a drain finger 32 adjacent to the sensing electrode 60 in a second direction X, a gate electrode 50 located between the drain finger 32 and the sensing electrode 60, and a Kelvin source portion 43. The sensing electrode 60 is located between the Kelvin source portion 43 and the gate electrode 50 in the second direction X. The sensing element 92 also includes a sensing resistor R based on the spacing between the sensing electrode 60 and the Kelvin source portion 43 in the second direction X. The sensing resistor R includes a two-dimensional electron gas 15 distributed beneath the region between the Kelvin source portion 43 and the sensing electrode 60. The sensing electrode 60 and the Kelvin source portion 43 are electrically connected via the sensing resistor R containing the two-dimensional electron gas 15.

[0025] exist Figure 1 In the diagram, the distribution area 81 of the two-dimensional electron gas 15 is represented as a shaded area. The distribution area 81 of the two-dimensional electron gas 15 is surrounded by the element separation area 82.

[0026] The second chip 20 is a gate driver that controls the operation of the first chip 10A. The second chip 20 has a first terminal 21, a second terminal 24, a first ground terminal 22, and a second ground terminal 23. The first terminal 21 and the second terminal 24 are located separately in a first direction Y. The first ground terminal 22 is located between the first terminal 21 and the second ground terminal 23 in the first direction Y. The second ground terminal 23 is located between the first ground terminal 22 and the second terminal 24 in the first direction Y.

[0027] The first chip 10A has a gate terminal 52, a sensing terminal 62, a first Kelvin source terminal 45, and a second Kelvin source terminal 47.

[0028] The gate terminal 52 is electrically connected to the gate electrode 50 via the gate wiring 51 within the first chip 10A. Furthermore, the gate terminal 52 is electrically connected to the first terminal 21 of the second chip 20 via wiring 71.

[0029] The sensing terminal 62 is electrically connected to the sensing electrode 60 via wiring 61 within the first chip 10A. Furthermore, the sensing terminal 62 is electrically connected to the second terminal 24 of the second chip 20 via wiring 74.

[0030] The first Kelvin source terminal 45 is located between the gate terminal 52 and the sensing terminal 62 in the first direction Y. The first Kelvin source terminal 45 is electrically connected to the source power supply section 41 via wiring 44 in the first chip 10A. In addition, the first Kelvin source terminal 45 is electrically connected to the first ground terminal 22 of the second chip 20 via wiring 72.

[0031] The second Kelvin source terminal 47 is located between the first Kelvin source terminal 45 and the sensing terminal 62 in the first direction Y. The second Kelvin source terminal 47 is electrically connected to the Kelvin source section 43 via wiring 46 within the first chip 10A. The Kelvin source section 43 is connected to wiring 44, which connects the first Kelvin source terminal 45 and the source power supply section 41. The second Kelvin source terminal 47 is electrically connected to the second ground terminal 23 of the second chip 20 via wiring 73.

[0032] The gate terminal 52 of the first chip 10A is supplied with a gate control signal from the first terminal 21 of the second chip 20. The first Kelvin source terminal 45 of the first chip 10A is supplied with a ground potential via the first ground terminal 22 of the second chip 20. The second Kelvin source terminal 47 of the first chip 10A is supplied with a ground potential via the second ground terminal 23 of the second chip 20. The voltage between the source electrode 40 and the gate electrode 50 is switched, for example, in the range of 0V to tens of V. By controlling the potential of the gate electrode 50, the current (main current) flowing between the drain finger 32 and the source finger 42 of the main element 91 can be turned on and off.

[0033] Furthermore, the current flowing in the sensing resistor R (sensing current) can be monitored based on the voltage between the sensing electrode 60 of the sensing element 92 and the Kelvin source electrode 43. From this sensing current, overcurrent and other detections of the main element 91 can be performed.

[0034] In this embodiment, the sensing element 92 can be easily and cost-effectively formed by configuring a portion of the fingers as sensing electrodes 60 during the process of forming the multi-finger structure electrode. Furthermore, the sensing electrodes 60 can be formed near the Kelvin source electrode portion 43, which does not lead to an increase in the area of ​​the sensing element 92 and reduces parasitic components (resistance, inductance, etc.).

[0035] Furthermore, a sensing resistor R is formed by a two-dimensional electronic gas 15 having the same temperature characteristics as the on-resistance of the main element 91, thereby improving the current sensing accuracy, especially at high temperatures.

[0036] The sensing resistance R is represented by ρ×Lr / Wr. ρ is the resistance of the thin film of the two-dimensional electron gas 15. Lr is the distance between the Kelvin source electrode 43 and the sensing electrode 60 in the second direction X. Wr is the width of the distribution region of the two-dimensional electron gas 15 distributed below the region between the Kelvin source electrode 43 and the sensing electrode 60 in the first direction Y. The resistance value of the sensing resistance R can be adjusted by using Lr and Wr.

[0037] The resistance of the sensing element 92, including the sensing resistor R, is lower than the resistance of a main element 91. For current to flow smoothly and uniformly within the first chip 10A, the resistance of the sensing resistor R needs to be sufficiently lower than the resistance of the main element 91 within a range capable of monitoring the generated voltage. For example, the resistance of the sensing resistor R is preferably less than 1 / 10 of the resistance of the main element 91.

[0038] In order to reduce the resistance value of the sensing resistor R, the distance Lr between the Kelvin source portion 43 and the sensing electrode 60 in the second direction X is preferably narrower than the distance between the drain finger 32 and the source finger 42 of the main element 91 in the second direction X.

[0039] Furthermore, in order to reduce the resistance value of the sensing resistor R, the width Wr of the first direction Y of the distribution region of the two-dimensional electron gas 15 distributed below the region between the Kelvin source electrode 43 and the sensing electrode 60 is preferably larger than the width of the first direction Y of the distribution region of the two-dimensional electron gas 15 between the drain finger 32 and the source finger 42 of the main element 91.

[0040] like Figure 1 As shown, in the first direction Y, a first Kelvin source terminal 45 forming a gate control cycle L1 with the gate terminal 52 is disposed between the gate terminal 52 and the sensing terminal 62, and a second Kelvin source terminal 47 forming a sensing current monitoring cycle L2 with the sensing terminal 62 is disposed between the first Kelvin source terminal 45 and the sensing terminal 62. This allows for the protection of small sensing voltages from the gate control signal and improves the monitoring and control of the sensing current.

[0041] For example, a sensing element 92 is disposed in the peripheral region (peripheral region of the chip) of an area where multiple main elements 91 are disposed. Furthermore, in Figure 4 as well as Figure 5 The first chip 10B shown has a plurality of sensing elements 92 disposed therein. That is, the first chip 10B includes a plurality of Kelvin source portions 43 and a plurality of sensing electrodes 60. The sensing elements 92 are disposed in the peripheral region of the region where a plurality of main elements 91 are disposed, and are also disposed in the region between the main elements 91. Thus, it is possible to monitor the current distribution in the peripheral region and the region inside the peripheral region of the first chip 10B.

[0042] Several embodiments of the present invention have been described, but these embodiments are merely illustrative and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are included within the scope of the invention as set forth in the claims and its equivalents.

Claims

1. A semiconductor device, characterized in that, have: First nitride semiconductor layer; A second nitride semiconductor layer is disposed on the first nitride semiconductor layer, and the band gap is wider than that of the first nitride semiconductor layer; The drain electrode has a plurality of drain fingers extending along a first direction; The source electrode has a plurality of source fingers extending along the first direction and a Kelvin source portion extending along the first direction and electrically connected to the source fingers. The sensing electrode is located between the adjacent drain finger and the Kelvin source in the second direction and extends along the first direction, the second direction intersecting the first direction; as well as A gate electrode is located between adjacent drain fingers and source fingers in the second direction, and between adjacent drain fingers and sensing electrodes in the second direction, and extends along the first direction. The sensing electrode and the Kelvin source are electrically connected via a sensing resistor based on the spacing between the sensing electrode and the Kelvin source in the second direction.

2. The semiconductor device according to claim 1, characterized in that, The distance between the Kelvin source portion and the sensing electrode in the second direction is narrower than the distance between the drain finger and the source finger in the second direction.

3. The semiconductor device according to claim 1 or 2, characterized in that, The width of the distribution region of the two-dimensional electron gas of the sensing resistor in the first direction is greater than the width of the distribution region of the two-dimensional electron gas between the drain finger and the source finger in the first direction.

4. The semiconductor device according to claim 1 or 2, characterized in that, It also has an insulating film disposed on the second nitride semiconductor layer. The drain finger, the source finger, the Kelvin source, and the sensing electrode are connected to the second nitride semiconductor layer. The gate electrode is located on the insulating film.

5. The semiconductor device according to claim 1 or 2, characterized in that, It also has: The gate terminal is connected to the gate electrode. A sensing terminal is connected to the sensing electrode; The first Kelvin source terminal is located between the gate terminal and the sensing terminal in the first direction, and is connected to the first ground terminal of the gate driver and the source electrode; as well as The second Kelvin source terminal is located between the first Kelvin source terminal and the sensing terminal in the first direction, and is connected to the second ground terminal of the gate driver and the source electrode.

6. The semiconductor device according to claim 1 or 2, characterized in that, It has multiple Kelvin source electrodes and multiple sensing electrodes.

7. The semiconductor device according to claim 1 or 2, characterized in that, The first nitride semiconductor layer is a GaN layer, and the second nitride semiconductor layer is an AlGaN layer.

8. The semiconductor device according to claim 1 or 2, characterized in that, The sensing resistor comprises a two-dimensional electron gas, which is distributed near the interface between the first nitride semiconductor layer and the second nitride semiconductor layer in the first nitride semiconductor layer.

9. The semiconductor device according to claim 1 or 2, characterized in that, The resistance value of the sensing resistor is lower than the resistance value of a main element, the main element including the drain finger, the source finger, and the gate electrode located between the drain finger and the source finger.

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