JP2017063120A - Semiconductor device - Google Patents

Abstract

A semiconductor device having a comb-shaped electrode structure in which heat generation due to a current flowing between electrodes during device operation is suppressed and a source electrode and a drain electrode are arranged in a crossed finger shape is provided. A semiconductor substrate, a comb-shaped source electrode having a comb handle portion and a plurality of comb teeth extending from the comb handle portion, and a comb-shaped source electrode disposed on the semiconductor substrate, and the semiconductor substrate. In addition, a comb-shaped drain electrode 4 having a comb-shaped portion facing the comb-shaped portion of the source electrode 3 and a plurality of comb-tooth portions arranged in a cross finger shape with the comb-tooth portion of the source electrode is provided. In the linear region in which the comb teeth of the source electrode 3 and the comb teeth of the drain electrode 4 extend linearly, the source is larger than the interval between the comb teeth of the source electrode 3 and the comb teeth of the drain electrode 4 adjacent to each other. The distance between the tip of the comb tooth portion of the electrode 3 and the comb handle portion of the drain electrode 4 and the distance between the tip of the comb tooth portion of the drain electrode 4 and the comb handle portion of the source electrode 3 are wider. [Selection] Figure 1

Description

  The present invention relates to a semiconductor device having comb-shaped electrodes.

  As an electrode structure of a semiconductor device, a comb-shaped electrode structure in which a source electrode and a drain electrode are arranged in an interdigital manner is used. For this reason, methods for solving various problems caused by comb-shaped electrodes have been implemented for semiconductor devices having a comb-shaped electrode structure. For example, in order to alleviate the electric field concentration in the tip region of the comb-shaped electrode, a method of increasing the distance between the electrodes in the tip region rather than the linear region of the comb-shaped electrode has been proposed (see, for example, Patent Document 1). .)

JP 2013-98222 A

  In a semiconductor device adopting a comb-shaped electrode structure, heat is generated in the electrode by a current flowing between the drain electrode and the source electrode during device operation. There is a concern that the reliability of the semiconductor device may be lowered, such as the semiconductor device malfunctioning or being destroyed by local heat generation at the electrodes. However, no studies have been made so far regarding heat generation due to the current flowing between the electrodes of the comb electrode structure of the semiconductor device.

  In view of the above problems, the present invention provides a semiconductor device having a comb-shaped electrode structure in which heat generation due to a current flowing between electrodes during device operation is suppressed and a source electrode and a drain electrode are arranged in a cross finger shape. With the goal.

  According to one aspect of the present invention, a comb-shaped source having (a) a semiconductor substrate and (b) a comb handle portion disposed on the semiconductor substrate and a plurality of comb teeth extending from the comb handle portion. A comb having an electrode, and (c) a comb handle portion disposed on the semiconductor substrate and facing the comb handle portion of the source electrode, and a plurality of comb teeth portions arranged in a cross-finger shape with the comb teeth portion of the source electrode A gap between the source electrode comb tooth portion and the drain electrode comb tooth portion in a linear region in which the source electrode comb tooth portion and the drain electrode comb tooth portion linearly extend. A semiconductor device is provided in which the distance between the tip of the comb tooth portion of the source electrode and the comb handle portion of the drain electrode and the distance between the tip of the comb tooth portion of the drain electrode and the comb handle portion of the source electrode are wider. .

  ADVANTAGE OF THE INVENTION According to this invention, the semiconductor device which has the comb-shaped electrode structure by which the heat_generation | fever by the electric current which flows between electrodes at the time of device operation was suppressed, and the source electrode and the drain electrode arrange | positioned in the shape of cross fingers can be provided.

1 is a schematic plan view showing a structure of a semiconductor device according to a first embodiment of the present invention. 1 is a schematic plan view showing a structure of a source tip region of a semiconductor device according to a first embodiment of the present invention. 1 is a schematic plan view showing a structure of a drain tip region of a semiconductor device according to a first embodiment of the present invention. It is a table | surface which shows the example of the space | interval between the electrodes in the semiconductor device which concerns on the 1st Embodiment of this invention. 1 is a schematic cross-sectional view showing a structure of a semiconductor device according to a first embodiment of the present invention. It is a typical top view which shows the structure of the semiconductor device which concerns on the 2nd Embodiment of this invention. It is typical sectional drawing which shows the structure of the semiconductor device which concerns on the 2nd Embodiment of this invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the lengths of the respective parts, and the like are different from the actual ones. Therefore, specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes the shape, structure, arrangement, etc. of components. It is not specified to the following. The embodiment of the present invention can be variously modified within the scope of the claims.

(First embodiment)
As shown in FIG. 1, the semiconductor device 1 according to the first embodiment of the present invention includes a comb-shaped source electrode 3 and a drain each having a plurality of comb teeth extending in the vertical direction toward the paper surface. An electrode 4 and a gate electrode 5 disposed between the source electrode 3 and the drain electrode 4 are provided. The semiconductor device 1 has a comb-shaped electrode structure in which the comb-tooth portion of the source electrode 3 and the comb-tooth portion of the drain electrode 4 are arranged in an interdigital manner.

  More specifically, the source electrode 3 has a comb shape having a comb handle portion and a plurality of comb teeth extending from the comb handle portion. The drain electrode 4 has a comb shape having a comb handle portion facing the comb handle portion of the source electrode 3 and a plurality of comb teeth portions arranged in a cross finger shape with the comb teeth portion of the source electrode 3. Thus, since each comb-tooth part of the drain electrode 4 is arrange | positioned between each comb-tooth part of the source electrode 3, the gate electrode 5 is arrange | positioned by folding | folding in multiple in the left-right direction toward the paper surface. .

  Hereinafter, a region in which the comb teeth of the source electrode 3 and the comb teeth of the drain electrode 4 extend in a straight line is referred to as a “linear region 100”. The region at the tip of the comb tooth portion of the source electrode 3 is referred to as “source tip region 101”, and the region at the tip of the comb tooth portion of the drain electrode 4 is referred to as “drain tip region 102”. The source tip region 101 and the drain tip region 102 are collectively referred to as “tip region”.

  FIG. 2 shows an enlarged view of the source tip region 101, and FIG. 3 shows an enlarged view of the drain tip region 102. As shown in FIG. In the example shown in FIGS. 2 and 3, the shape of the tips of the comb teeth of the source electrode 3 and the drain electrode 4 is semicircular. In the source tip region 101, the outer edge of the handle portion of the drain electrode 4 is recessed in a semicircular shape along the tip of the comb tooth portion of the source electrode 3. Similarly, in the drain tip region 102, the outer edge of the handle portion of the source electrode 3 is recessed in a semicircular shape along the tip of the comb tooth portion of the drain electrode 4. For this reason, the gate electrode 5 disposed between the source electrode 3 and the drain electrode 4 has an arc shape in the tip region.

  As shown in FIGS. 2 and 3, the distance between the comb teeth of the source electrode 3 and the comb teeth of the drain electrode 4 adjacent to each other in the linear region 100 is b. Further, the distance between the tip of the comb tooth portion of the source electrode 3 and the comb handle portion of the drain electrode 4 in the source tip region 101 is a1. Further, the distance between the tip of the comb tooth portion of the drain electrode 4 and the comb handle portion of the source electrode 3 in the drain tip region 102 is a2. The interval a1 and the interval a2 are distances from the tip of the comb tooth portion to the opposing comb handle portion.

  In the semiconductor device 1, the interval a1 and the interval a2 are set wider than the interval b. Thereby, the following effects are obtained.

  In general, in the comb electrode structure, the drain current flowing between the drain electrode and the source electrode during device operation tends to concentrate and flow in the tip region compared to the straight region. This is because the current between the electrodes flows more easily in the tip region of the electrode than in the linear region in terms of shape. When the drain current is concentrated in the tip region, the current density in the tip region increases, and the amount of heat generated in the tip region increases. This heat generation may cause device destruction or malfunction, and may reduce the reliability of the semiconductor device.

  On the other hand, in the semiconductor device 1 shown in FIG. 1, the distance between the source electrode 3 and the drain electrode 4 is larger in the distance a1 and the distance a2 in the tip region than in the distance b in the straight line region 100. For this reason, during the device operation, the drain current flows more easily in the linear region 100 than in the tip region from the viewpoint of the interelectrode distance. Therefore, according to the semiconductor device 1, the drain current is dispersed throughout the drain electrode 4 and the source electrode 3, and the concentration of the drain current in the tip region is suppressed. As a result, heat generation due to concentration of drain current is suppressed, and device breakdown can be prevented.

  In addition, when the semiconductor device 1 is in the ON state, the interval a1, the current density of the drain current flowing from the drain electrode 4 to the source electrode 3 is equal in the linear region 100, the source tip region 101, and the drain tip region 102. The relationship between the interval a2 and the interval b is preferably set.

  As a result of repeated studies, the inventors have relaxed the drain current concentration in the tip region when the interval a1 and the interval a2 are 1.1 to 10 times the interval b, and the current concentration of the semiconductor device 1 is reduced. It has been found that device destruction and malfunction due to the generated heat can be suppressed. Further, according to the study by the inventors, the interval a1 and the interval a2 are more preferably 1.5 times the interval b. By making it 1.5 times, device destruction due to heat generation can be prevented, and at the same time, a device having a low electrical resistance between the source and the drain can be obtained.

  In FIG. 4, the example of the space | interval between the electrodes in an Example is shown. The sample 1 shown in FIG. 4 is an example in which each of the interval a1 and the interval a2 in the tip region is 1.5 times the interval b in the linear region 100. In addition, as shown in the sample 2, the interval a1 and the interval a2 may not be the same. Further, as shown in the sample 3, the ratio of the interval a1 and the interval a2 to the interval b is not limited to 1.5.

  The semiconductor device 1 is a nitride semiconductor device having the structure shown in FIG. The structure of the semiconductor device 1 shown in FIG. 5 will be described below.

  As shown in FIG. 5, the semiconductor device 1 includes a semiconductor substrate 2 having a structure in which a buffer layer 11 and a nitride semiconductor layer 20 are stacked on a substrate 10. A source electrode 3, a drain electrode 4, and a gate electrode 5 are disposed on the semiconductor substrate 2. Nitride semiconductor devices using nitride semiconductors are used in high voltage power devices. A typical nitride semiconductor is represented by AlxInyGa1-x-yN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1), and includes gallium nitride (GaN), aluminum nitride (AlN), and indium nitride. (InN).

  The semiconductor device 1 shown in FIG. 5 is a high electron mobility transistor (HEMT) having a nitride semiconductor layer 20 in which a carrier traveling layer 21 and a carrier supply layer 22 made of nitride semiconductors having different band gap energies are stacked. is there. A heterojunction surface is formed at the interface between the carrier traveling layer 21 and the carrier supply layer 22, and a two-dimensional carrier gas layer 23 as a current path (channel) is formed in the carrier traveling layer 21 near the heterojunction surface.

  As shown in FIG. 5, the interlayer insulating film 6 is disposed on the nitride semiconductor layer 20 so as to cover the source electrode 3, the drain electrode 4, and the gate electrode 5. The source electrode wiring 31 is connected to the source electrode 3 and the drain electrode wiring 41 is connected to the drain electrode 4 through the openings formed in the interlayer insulating film 6.

  As the substrate 10, a semiconductor substrate such as a silicon (Si) substrate, a silicon carbide (SiC) substrate, or a GaN substrate, or an insulator substrate such as a sapphire substrate or a ceramic substrate can be employed.

  The buffer layer 11 can be formed by an epitaxial growth method such as a metal organic chemical vapor deposition (MOCVD) method. Since the buffer layer 11 is not directly related to the operation of the HEMT, the buffer layer 11 may be omitted. A structure in which the substrate 10 and the buffer layer 11 are combined can be regarded as a substrate. Whether or not the buffer layer 11 is structured and arranged is determined according to the material and film thickness of the substrate 10 and the nitride semiconductor layer 20.

  The carrier traveling layer 21 is formed, for example, by epitaxially growing non-doped GaN to which no impurity is added by the MOCVD method or the like. Here, non-doped means that no impurity is intentionally added.

  The carrier supply layer 22 disposed on the carrier traveling layer 21 is made of a nitride semiconductor having a band gap larger than that of the carrier traveling layer 21 and a lattice constant smaller than that of the carrier traveling layer 21. Non-doped AlxGa1-xN can be used as the carrier supply layer 22. The carrier supply layer 22 is formed on the carrier traveling layer 21 by epitaxial growth using the MOCVD method or the like. Since the carrier supply layer 22 and the carrier traveling layer 21 have different lattice constants, piezoelectric polarization due to lattice distortion occurs. Due to the piezoelectric polarization and the spontaneous polarization of the crystal of the carrier supply layer 22, high-density carriers are generated in the carrier traveling layer 21 near the heterojunction, and a two-dimensional carrier gas layer 23 is formed.

  The source electrode 3 and the drain electrode 4 are formed of a metal capable of low resistance contact (ohmic contact) with the nitride semiconductor layer 20. For example, aluminum (Al), titanium (Ti), or the like can be used for the source electrode 3 and the drain electrode 4. Alternatively, the source electrode 3 and the drain electrode 4 are formed as a laminate of Ti and Al.

  For the gate electrode 5, for example, nickel gold (NiAu) can be used. For the source electrode wiring 31 and the drain electrode wiring 41, for example, Al, gold (Au), copper (Cu), or the like can be employed.

  In the above description, the semiconductor device 1 is a HEMT. However, even when the semiconductor device 1 is a transistor other than a HEMT, for example, a lateral FET, the above-described comb electrode structure can be employed.

  As described above, in the semiconductor device 1 according to the first embodiment of the present invention, the distance between the source electrode 3 and the drain electrode 4 is wider in the source tip region 101 and the drain tip region 102 than in the straight region 100. Is set. For this reason, according to the semiconductor device 1, the concentration of the drain current in the tip region is reduced. As a result, heat generation in the tip region is suppressed, and device destruction or malfunction is prevented. Thereby, the reliability of the semiconductor device 1 is improved.

(Second Embodiment)
The semiconductor device 1 according to the second embodiment of the present invention is different from FIG. 1 in that the gate electrode 5 is not disposed as shown in FIG. Other configurations are the same as those of the semiconductor device 1 shown in FIG. The semiconductor device 1 shown in FIG. 6 is a diode in which comb-shaped source electrodes 3 and drain electrodes 4 are arranged in a crossed finger shape. A sectional view of the semiconductor device 1 shown in FIG. 6 is shown in FIG. The semiconductor device 1 shown in FIG. 7 has a structure in which a source electrode 3 and a drain electrode 4 are disposed on a semiconductor substrate 2.

  Even when the semiconductor device 1 is a diode, the present invention can be applied in the same manner as the transistor shown in FIG. That is, the distance a 1 between the tip of the comb tooth portion of the source electrode 3 and the comb handle portion of the drain electrode 4 and the distance b between the comb tooth portion of the source electrode 3 and the comb tooth portion of the drain electrode 4 in the straight region 100. The distance a2 between the tip of the comb tooth portion of the drain electrode 4 and the comb handle portion of the source electrode 3 is set wider. Thereby, the forward current concentration of the diode in the tip region of the source electrode 3 and the drain electrode 4 is alleviated. As a result, device destruction or malfunction can be prevented. Others are substantially the same as those in the first embodiment, and redundant description is omitted.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

For example, in the above description, the case where the semiconductor device 1 is a nitride semiconductor device in which the semiconductor substrate 2 includes the nitride semiconductor layer 20 is exemplified. However, even in the case of the semiconductor device 1 in which the semiconductor substrate 2 is a stacked body of silicon semiconductor layers, according to the present invention, current concentration at the tips of the comb-shaped source electrode 3 and drain electrode 4 can be reduced. As a result, even when the semiconductor device 1 is a silicon semiconductor device, heat generation due to the current flowing between the electrodes during device operation can be suppressed, and reliability can be improved. It goes without saying that the embodiment and the like are included. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device 2 ... Semiconductor base | substrate 3 ... Source electrode 4 ... Drain electrode 5 ... Gate electrode 100 ... Linear region 101 ... Source tip region 102 ... Drain tip region

Claims (6)

A semiconductor substrate;
A comb-shaped source electrode having a comb handle portion and a plurality of comb teeth extending from the comb handle portion, disposed on the semiconductor substrate;
A comb shape having a comb handle portion disposed on the semiconductor substrate and opposed to the comb handle portion of the source electrode, and a plurality of comb teeth portions arranged in a cross-finger shape with the comb teeth portion of the source electrode. A drain electrode having a shape, and
A distance b between the comb tooth portion of the source electrode and the comb tooth portion of the drain electrode adjacent to each other in a linear region in which the comb tooth portion of the source electrode and the comb tooth portion of the drain electrode extend linearly. Rather, the distance a1 between the tip of the comb tooth portion of the source electrode and the comb handle portion of the drain electrode and the distance a2 between the tip of the comb tooth portion of the drain electrode and the comb handle portion of the source electrode. A semiconductor device characterized by being wider.   In the on-state, the current density of the current flowing between the comb-tooth portion of the drain electrode and the comb-tooth portion of the source electrode in the linear region is such that the tip of the comb-tooth portion of the source electrode and the drain The current density of the current flowing between the comb handle portion of the electrode and the current density of the current flowing between the tip of the comb tooth portion of the drain electrode and the comb handle portion of the source electrode are equal to each other. The semiconductor device according to claim 1.   3. The semiconductor device according to claim 1, wherein the interval a <b> 1 and the interval a <b> 2 are not less than 1.1 times and not more than 10 times the interval b.   4. The semiconductor device according to claim 3, wherein the interval a1 and the interval a2 are 1.5 times the interval b.   5. The semiconductor device according to claim 1, further comprising a gate electrode disposed on the semiconductor substrate between the source electrode and the drain electrode. 6.   6. The semiconductor substrate according to claim 1, wherein the semiconductor substrate has a structure in which a carrier supply layer made of a nitride semiconductor and a carrier traveling layer that forms a heterojunction with the carrier supply layer are stacked. The semiconductor device described.

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