Semiconductor Devices

Abstract

To provide a semiconductor device capable of stabilizing characteristics.SOLUTION: According to an embodiment, a semiconductor device includes a first electrode, a second electrode, a third electrode, a first semiconductor region, a second semiconductor region, a first conductive member, and an insulation member. A location of the third electrode in a first direction is between a location of the first electrode in the first direction and a location of the second electrode in the first direction. The insulation member includes a first nitride region and a second nitride region. A first ratio of silicon concentration to nitride concentration in the first nitride region is lower than a second ratio of silicon concentration to nitride concentration in the second nitride region. The first nitride region includes a first nitride end part. The first nitride end part is in contact with the second semiconductor region and faces the second nitride region in the first direction. A location of the first nitride end part in the first direction is between a location of a first conductive end part in the first direction and a location of the second electrode in the first direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a semiconductor device. [Background technology]

[0002] Stable characteristics are desired in semiconductor devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-175018 Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments of the present invention provide a semiconductor device capable of stabilizing characteristics. [Means for solving the problem]

[0005] According to an embodiment of the present invention, a semiconductor device includes a first electrode, a second electrode, a third electrode, a first semiconductor region, a second semiconductor region, a first conductive member, and an insulating member. A direction from the first electrode to the second electrode is along a first direction. A position of the third electrode in the first direction is between a position of the first electrode in the first direction and a position of the second electrode in the first direction. The first semiconductor region is Al x1 Ga 1-x1It includes N(0≦x1<1). The first semiconductor region includes a first partial region, a second partial region, a third partial region, a fourth partial region, a fifth partial region, and a sixth partial region. The directions from the first partial region to the first electrode, from the second partial region to the second electrode, and from the third partial region to the third electrode are along a second direction that intersects the first direction. The fourth partial region is between the first partial region and the third partial region in the first direction. The fifth partial region is between the third partial region and the second partial region in the first direction. The sixth partial region is between the fifth partial region and the second partial region in the first direction. The second semiconductor region contains Al x2 Ga 1-x2 It includes N(0<x2≦1, x1<x2). The second semiconductor region includes a first semiconductor part, a second semiconductor part, and a third semiconductor part. The direction from the fourth partial region to the first semiconductor part is along the second direction. The first conductive member is electrically connected to, or can be electrically connected to, one of the first electrode and the third electrode. The first conductive member includes a first conductive end portion in the first direction. The position of the first conductive end portion in the first direction is between the position of the third electrode in the first direction and the position of the second electrode in the first direction. The insulating member includes a first nitride region and a second nitride region. The second semiconductor part is between the fifth partial region and the first nitride region in the second direction. The third semiconductor part is between the sixth partial region and the second nitride region in the second direction. The first nitride region contains silicon and nitrogen. The second nitride region contains silicon and nitrogen. A first ratio of the concentration of silicon to the concentration of nitrogen in the first nitride region is lower than a second ratio of the concentration of silicon to the concentration of nitrogen in the second nitride region. The first nitride region includes a first nitride end portion. The first nitride end portion is in contact with the second semiconductor region and faces the second nitride region in the first direction. The position of the first nitride end portion in the first direction is between the position of the first conductive end portion in the first direction and the position of the second electrode in the first direction. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 2] FIG. 2 is a graph illustrating the characteristics of the semiconductor device. [Figure 3] FIG. 3 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 5] FIG. 5 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 7] FIG. 7 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 8] FIG. 8 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. [Figure 9] FIG. 9 is a schematic cross-sectional view illustrating the semiconductor device according to the second embodiment. [Figure 10] FIG. 10 is a schematic cross-sectional view illustrating the semiconductor device according to the third embodiment. [Figure 11] FIG. 11 is a schematic cross-sectional view illustrating a semiconductor device according to the third embodiment. [Figure 12] FIG. 12 is a schematic cross-sectional view illustrating the semiconductor device according to the fourth embodiment. [Figure 13] FIG. 13 is a schematic cross-sectional view illustrating the semiconductor device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and in each drawing, elements similar to those previously described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0008] (First embodiment) FIG. 1 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. As shown in FIG. 1, the semiconductor device 110 according to the embodiment includes a first electrode 51, a second electrode 52, a third electrode 53, a first semiconductor region 10, a second semiconductor region 20, a first conductive member 61, and an insulating member 40.

[0009] The direction from the first electrode 51 to the second electrode 52 is along the first direction. The first direction is the X-axis direction. One direction perpendicular to the X-axis direction is the Z-axis direction. The direction perpendicular to the X-axis and Z-axis directions is the Y-axis direction.

[0010] The position of the third electrode 53 in the first direction (X-axis direction) is between the position of the first electrode 51 in the first direction and the position of the second electrode 52 in the first direction. In one example, at least a portion of the third electrode 53 is between the first electrode 51 and the second electrode 52 in the first direction.

[0011] The first semiconductor region 10 is Al x1 Ga 1-x1 N (0≦x1<1). The composition ratio x1 is, for example, equal to or greater than 0 and less than 0.2. In one example, the first semiconductor region 10 is a GaN layer. Alternatively, the first semiconductor region 10 may be an AlGaN layer with a low Al composition ratio (for example, less than 0.2).

[0012] The first semiconductor region 10 includes a first partial region 10a, a second partial region 10b, a third partial region 10c, a fourth partial region 10d, a fifth partial region 10e, and a sixth partial region 10f. The directions from the first partial region 10a to the first electrode 51, from the second partial region 10b to the second electrode 52, and from the third partial region 10c to the third electrode 53 are along the second direction. The second direction is, for example, the Z-axis direction. For example, the first partial region 10a is a portion that overlaps with the first electrode 51 in the second direction. For example, the second partial region 10b is a portion that overlaps with the second electrode 52 in the second direction. For example, the third partial region 10c is a portion that overlaps with the third electrode 53 in the second direction.

[0013] The fourth partial region 10d is located between the first partial region 10a and the third partial region 10c in the first direction (X-axis direction). The fifth partial region 10e is located between the third partial region 10c and the second partial region 10b in the first direction. The sixth partial region 10f is located between the fifth partial region 10e and the second partial region 10b in the first direction. The boundaries between the first to sixth partial regions 10a to 10f may be unclear. Each of these partial regions may be a "partial position" within the first semiconductor region 10.

[0014] The second semiconductor region 20 is Al x2 Ga 1-x2 N (0 < x2 ≤ 1, x1 < x2). The composition ratio x2 is, for example, 0.05 or more and 1 or less. The second semiconductor region 20 is an AlGaN layer. The composition ratio of Al in the second semiconductor region 20 is higher than the composition ratio of Al in the first semiconductor region 10.

[0015] The second semiconductor region 20 includes a first semiconductor portion 21, a second semiconductor portion 22, and a third semiconductor portion 23. The direction from the fourth sub-region 10d to the first semiconductor portion 21 is along the second direction (Z-axis direction). The direction from the fifth sub-region 10e to the second semiconductor portion 22 is along the second direction (Z-axis direction). The direction from the sixth sub-region 10f to the third semiconductor portion 23 is along the second direction (Z-axis direction). As shown in FIG. 1, the second semiconductor region 20 may include a fourth semiconductor portion 24. The fourth semiconductor portion 24 is located between the third sub-region 10c and the third electrode 53 in the second direction. The boundaries between the first to fourth semiconductor portions 21 to 24 may be unclear.

[0016] The first conductive member 61 is electrically connected to a first one of the first electrode 51 and the third electrode 53. Alternatively, the first conductive member 61 can be electrically connected to the first one. In this example, the first conductive member 61 is electrically connected to the first electrode 51 by a connection member 61S. The connection member 61S may be provided at a position different from that shown in the cross section of FIG. 1 . The connection member 61S may be provided separately from the semiconductor device 110.

[0017] The first conductive member 61 includes an end portion (first conductive end portion 61e) in the first direction (X-axis direction). The position of the first conductive end portion 61e in the first direction is between the position of the third electrode 53 in the first direction and the position of the second electrode 52 in the first direction. The first conductive end portion 61e is the end portion of the first conductive member 61 on the second electrode 52 side.

[0018] The insulating member 40 includes a first nitride region 41 and a second nitride region 42. The second semiconductor portion 22 is located between the fifth sub-region 10e and the first nitride region 41 in the second direction (the Z-axis direction). The third semiconductor portion 23 is located between the sixth sub-region 10f and the second nitride region 42 in the second direction.

[0019] The first nitride region 41 contains silicon and nitrogen. The second nitride region 42 contains silicon and nitrogen. These nitride regions are, for example, silicon nitride layers.

[0020] The ratio of the silicon concentration to the nitrogen concentration in the first nitride region 41 is defined as a first ratio (Si / Ni). The ratio of the silicon concentration to the nitrogen concentration in the second nitride region 42 is defined as a second ratio (Si / N). These concentration ratios correspond to the silicon composition ratio to the nitrogen composition ratio. In the embodiment, the first ratio is lower than the second ratio. The first nitride region 41 is, for example, a relatively N-rich silicon nitride layer. The second nitride region 42 is, for example, a relatively Si-rich silicon nitride layer. The Si and nitrogen composition ratios can be changed by changing the conditions for forming the nitride regions (for example, the flow rates of the Si source gas and the nitrogen source gas).

[0021] The first nitride region 41 includes a first nitride end 41e. The first nitride end 41e contacts the second semiconductor region 20 and faces the second nitride region 42 in the first direction (X-axis direction). The first nitride end 41e is the end of the first nitride region 41 on the second electrode 52 side. The first nitride end 41e may contact the second nitride region 42.

[0022] The position of the first nitride end 41e in the first direction (X-axis direction) is between the position of the first conductive end 61e in the first direction and the position of the second electrode 52 in the first direction. For example, the distance between the first nitride end 41e and the second electrode 52 is shorter than the distance between the first conductive end 61e and the second electrode 52.

[0023] For example, a carrier region 10C is formed in a region of the first semiconductor region 10 facing the second semiconductor region 20. The carrier region 10C is, for example, a two-dimensional electron gas. The distance between the first electrode 51 and the third electrode 53 is shorter than the distance between the second electrode 52 and the third electrode 53.

[0024] The current flowing between the first electrode 51 and the second electrode 52 can be controlled by the potential of the third electrode 53. The potential of the third electrode 53 is, for example, a potential based on the potential of the first electrode 51. The first electrode 51 functions as, for example, a source electrode. The second electrode 52 functions as, for example, a drain electrode. The third electrode 53 functions as, for example, a gate electrode. The semiconductor device 110 is, for example, a HEMT (High Electron Mobility Transistor). The first conductive member 61 functions as, for example, a field plate. The provision of the first conductive member 61 suppresses concentration of an electric field.

[0025] As described above, nitride regions with different compositions are provided in the semiconductor device 110 according to the embodiment. The end of the first nitride region 41 (first nitride end 41e) is provided between the first conductive end 61e and the second electrode 52. This makes it possible to suppress, for example, current collapse. For example, it is possible to maintain a high breakdown voltage. According to the embodiment, it is possible to provide a semiconductor device with stable characteristics.

[0026] For example, there is a reference example in which a nitride region with a uniform composition is provided on the second semiconductor region 20 instead of the first nitride region 41 and the second nitride region 42, which have different compositions. In this reference example, if the entire nitride region is N-rich, the current collapse increases. On the other hand, in the reference example, if the entire nitride region is Si-rich, the breakdown voltage tends to decrease.

[0027] It has been found that current collapse tends to depend on the characteristics in the vicinity of the second electrode 52 (e.g., drain electrode). On the other hand, it has been found that the breakdown voltage tends to depend on the characteristics in the vicinity of the third electrode 53 (e.g., gate electrode) and the first conductive member 61 (e.g., field plate). In the embodiment, the composition ratio of the nitride region is changed in the region between the third electrode 53 and the second electrode 52. This makes it possible to obtain a high breakdown voltage while suppressing current collapse. According to the embodiment, a semiconductor device with stable characteristics can be provided.

[0028] For example, applying a silicon-rich nitride region near the gate electrode tends to reduce the breakdown voltage. This is thought to be due to the following reasons.

[0029] When the composition ratio Si / N in the nitride region is high and the nitride region becomes Si-rich, for example, the depletion voltage of the carrier region 10C (two-dimensional electron gas) increases. Therefore, when a Si-rich nitride region is applied near the gate electrode, the depletion layer becomes less likely to spread toward the drain electrode as the depletion voltage increases. Therefore, when a Si-rich nitride region is applied near the gate electrode, the electric field tends to concentrate near the gate electrode. This tends to reduce the breakdown voltage.

[0030] When the depletion layer reaches the drain electrode, the electric field concentrates near the drain electrode, making it more likely that current collapse will occur. By applying a Si-rich nitride region near the drain electrode, the voltage at which the depletion layer reaches the drain electrode can be increased, thereby suppressing current collapse.

[0031] For example, by lowering the Si / N ratio in the nitride region near the third electrode 53 (N-rich) and raising the Si / N ratio in the nitride region near the second electrode 52 (Si-rich), it is possible to suppress current collapse while maintaining a high breakdown voltage.

[0032] 1, the second electrode 52 includes a second electrode end portion 52e. The second electrode end portion 52e contacts the third semiconductor portion 23 (second semiconductor region 20) and the second nitride region 42. The second electrode end portion 52e corresponds to the end portion on the third electrode 53 side of the portion where the second electrode 52 and the second semiconductor region 20 contact each other.

[0033] The distance along the first direction (X-axis direction) between the position of the first conductive end 61e and the position of the first nitride end 41e in the first direction is defined as a first distance L1. The distance along the first direction between the position of the first conductive end 61e in the first direction and the position of the second electrode end 52e in the first direction is defined as a second distance L2. In the embodiment, the first distance L1 is greater than 0. The first distance L1 is less than the second distance L2.

[0034] FIG. 2 is a graph illustrating the characteristics of the semiconductor device. FIG. 2 illustrates the characteristics when the first nitride region 41 and the second nitride region 42 are provided on the second semiconductor region 20. The horizontal axis of FIG. 2 represents the ratio RL of the first distance L1 to the second distance L2. When the ratio RL is 0, the first nitride end 41e overlaps with the first conductive end 61e in the Z-axis direction. When the ratio RL is 1, the first nitride end 41e overlaps with the second electrode end 52e in the Z-axis direction. The vertical axis of FIG. 2 represents the resistance increase rate CC1 when a drain voltage stress is applied. The level of the resistance increase rate CC1 corresponds to the magnitude of current collapse. In this example, the Si / N ratio in the first nitride region 41 is 0.69, and the Si / N ratio in the second nitride region 42 is 0.80. In FIG. 2, three black circles are shown for each ratio RL. The three black circles correspond to three data points obtained for one ratio RL. The open circle corresponds to the median of the triplicate data.

[0035] As shown in FIG. 2, under these conditions, when the ratio RL is lower than 0.15 (lower than the dashed line in the figure), dielectric breakdown occurs. When the ratio RL is 0.15 or higher, a small current collapse occurs when the resistance increase rate CC1 is low. In the embodiment, the ratio RL is preferably 0.43 or higher. This makes it easier to obtain a high breakdown voltage. It is more preferable that the ratio RL is 0.7 or higher. This makes it possible to stably obtain a high breakdown voltage and effectively suppress current collapse. The ratio RL is preferably less than 1. The ratio RL is preferably, for example, 0.96 or less.

[0036] In the embodiment, the first ratio (Si / N) in the first nitride region 41 is preferably lower than, for example, 0.75. The first ratio may be 0.72 or less.

[0037] In the embodiment, the second ratio (Si / N) in the second nitride region 42 is preferably, for example, 0.75 or more. The second ratio may be 0.75 or more and 0.96 or less. The second ratio may be 0.78 or more and 0.96 or less. The second ratio may be 0.78 or more and 0.93 or less. The second ratio may be 0.78 or more and 0.85 or less.

[0038] As shown in FIG. 1, the semiconductor device 110 may include a base 10s and a nitride layer 11B. The nitride layer 11B is provided on the base 10s. A first semiconductor region 10 is provided on the nitride layer 11B. A second semiconductor region 20 is provided on the first semiconductor region 10. The base 10s is, for example, a substrate. The base 10s may be, for example, a silicon substrate or a SiC substrate. The nitride layer 11B may include, for example, a nitride semiconductor. The nitride layer 11B includes, for example, Al, Ga, and N. The nitride layer 11B is, for example, a buffer layer.

[0039] As shown in FIG. 1, the thickness of the first nitride region 41 along the second direction (Z-axis direction) is defined as thickness t1. Thickness t1 is, for example, 0.5 nm or more and 300 nm or less. The thickness of the second nitride region 42 along the second direction is defined as thickness t2. Thickness t2 is preferably, for example, 0.5 nm or more and 300 nm or less. With such a thickness, for example, a desired threshold voltage can be easily obtained. With such a thickness, for example, high gate reliability can be easily obtained. For example, thickness t1 may be 10 nm or more and 100 nm or less.

[0040] As shown in FIG. 1 , the portion 40p of the insulating member 40 may be provided between the third electrode 53 and the first conductive member 61. The portion 40p of the insulating member 40 includes, for example, silicon and a first element. The first element includes at least one of oxygen and nitrogen. In one example, the portion 40p of the insulating member 40 includes silicon oxide. In this case, the portion 40p of the insulating member 40 may not include nitrogen. Alternatively, the nitrogen concentration in the first nitride region 41 and the second nitride region 42 may be higher than the nitrogen concentration in the portion 40p of the insulating member 40. The portion 40p of the insulating member 40 electrically insulates the third electrode 53 from the first conductive member 61. The portion 40p of the insulating member 40 may be silicon nitride.

[0041] 1, at least a portion of the second nitride region 42 contacts the third semiconductor portion 23. At least a portion of the first nitride region 41 contacts the second semiconductor portion 22. In this example, the direction from the first nitride region 41 to the second nitride region 42 is along the first direction (X-axis direction).

[0042] Hereinafter, several examples of semiconductor devices according to the embodiments will be described. FIG. 3 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. 3, in the semiconductor device 110a according to the embodiment, at least a portion of the second nitride region 42 is located between the third semiconductor portion 23 and a portion of the first nitride region 41 in the second direction (Z-axis direction). For example, a portion of the first nitride region 41 is provided on the second nitride region 42. Other configurations of the semiconductor device 110a may be similar to those of the semiconductor device 110.

[0043] FIG. 4 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. 4, in the semiconductor device 110b according to the embodiment, at least a portion of the first nitride region 41 is located between the second semiconductor portion 22 and a portion of the second nitride region 42 in the second direction (Z-axis direction). For example, a portion of the second nitride region 42 is provided on the first nitride region 41. Other configurations of the semiconductor device 110b may be similar to those of the semiconductor device 110.

[0044] FIG. 5 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. 5, in the semiconductor device 110c according to the embodiment, the third electrode 53 is located in the second direction (Z-axis direction) between a part of the first nitride region 41 and a part of the second nitride region 42. Other configurations of the semiconductor device 110c may be similar to those of the semiconductor device 110b.

[0045] In the semiconductor devices 110a to 110c, for example, current collapse can be suppressed, a high breakdown voltage can be maintained, and semiconductor devices with stable characteristics can be provided.

[0046] In the semiconductor devices 110 and 110a to 110c, a portion of the first nitride region 41 is located between the second semiconductor region 20 and the third electrode 53 in the second direction (Z-axis direction). A portion of the first nitride region 41 is located between the third partial region 10c and the third electrode 53.

[0047] FIG. 6 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. 6, in the semiconductor device 111 according to the embodiment, the first conductive member 61 is electrically connected to the third electrode 53 by a connecting member 61G. Other configurations of the semiconductor device 111 may be similar to those of the semiconductor device 110.

[0048] FIG. 7 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. 7, a semiconductor device 112 according to this embodiment is provided with a first conductive member 61 and a second conductive member 62. Other configurations of the semiconductor device 112 may be similar to those of the semiconductor device 110.

[0049] As already explained, the first conductive member 61 is electrically connected to a first one of the first electrode 51 and the third electrode 53. Alternatively, the first conductive member 61 can be electrically connected to the first one of the first and third electrodes 51 and 53. In this example, the first conductive member 61 is electrically connected to the first electrode 51 by the connection member 61S.

[0050] The second conductive member 62 is electrically connected to a second one of the first electrode 51 and the third electrode 53. Alternatively, the second conductive member 62 can be electrically connected to the second one. The second one may be the other of the first electrode 51 and the third electrode 53. In this example, the second conductive member 62 is electrically connected to the third electrode 53 by a connection member 62G.

[0051] The second conductive member 62 includes a second conductive end 62e in the first direction (X-axis direction). The position of the second conductive end 62e in the first direction is between the position of the third electrode 53 in the first direction and the position of the first conductive end 61e in the first direction. The second conductive member 62 functions as a second field plate. The provision of the second conductive member 62 further suppresses the concentration of the electric field.

[0052] The position of the second conductive member 62 in the second direction (Z-axis direction) is between the position of the third electrode 53 in the second direction and the position of the first conductive member 61 in the second direction.

[0053] FIG. 8 is a schematic cross-sectional view illustrating the semiconductor device according to the first embodiment. 8, the semiconductor device 113 according to the embodiment is provided with a first conductive member 61, a second conductive member 62, and a third conductive member 63. Other configurations of the semiconductor device 113 may be similar to those of the semiconductor devices 110 to 112.

[0054] The third conductive member 63 is electrically connected to the second electrode 52. Alternatively, the third conductive member 63 can be electrically connected to the second electrode 52. In this example, the third conductive member 63 is electrically connected to the second electrode 52 by a connection member 63D.

[0055] The third conductive member 63 includes a third conductive end 63e in the first direction (first direction). The third conductive end 63e is, for example, the end of the third conductive member 63 on the side of the third electrode 53. The position of the first nitride end 41e in the first direction (first direction) is between the position of the first conductive end 61e in the first direction and the position of the third conductive end 63e in the first direction.

[0056] In the semiconductor devices 111 to 113, for example, current collapse can be suppressed, a high breakdown voltage can be maintained, and semiconductor devices with stable characteristics can be provided.

[0057] (Second embodiment) FIG. 9 is a schematic cross-sectional view illustrating the semiconductor device according to the second embodiment. 9, the semiconductor device 120 according to the embodiment also includes first to third electrodes 51 to 53, a first semiconductor region 10, a second semiconductor region 20, a first conductive member 61, and an insulating member 40. The insulating member 40 includes a first insulating film 45. In the semiconductor device 120, the first to third electrodes 51 to 53, the first semiconductor region 10, the second semiconductor region 20, and the first conductive member 61 can have the same configuration as described in relation to the first embodiment.

[0058] The first insulating film 45 includes a first insulating region 45a. The first insulating region 45a is provided between the third partial region 10c and the third electrode 53. The first insulating region 45a functions as, for example, a gate insulating film.

[0059] The first insulating film 45 contains silicon and oxygen. The first insulating film 45 does not contain nitrogen. Alternatively, the concentration of nitrogen in the first insulating film 45 is lower than the concentration of nitrogen in the second nitride region 42. The first insulating film 45 is, for example, a silicon oxide film (e.g., a silicon dioxide film). By providing the first insulating film 45, the change in threshold voltage can be further suppressed.

[0060] The semiconductor device 120 also has a first nitride region 41 and a second nitride region 42. A first ratio (Si / N) of the silicon concentration to the nitrogen concentration in the first nitride region 41 is lower than a second ratio (Si / N) of the silicon concentration to the nitrogen concentration in the second nitride region 42. The position of the first nitride end 41e in the first direction (X-axis direction) is between the position of the first conductive end 61e in the first direction and the position of the second electrode 52 in the first direction. For example, current collapse can be suppressed. For example, a high breakdown voltage can be maintained. A semiconductor device with stable characteristics can be provided.

[0061] 9, in this example, at least a portion of the third electrode 53 is located between the first semiconductor portion 21 and the second semiconductor portion 22 in the first direction (X-axis direction). The third electrode 53 is a recessed gate. With this configuration, for example, a high threshold voltage can be easily obtained. For example, normally-off characteristics can be obtained.

[0062] 9, the first insulating film 45 may include a second insulating region 45b and a third insulating region 45c. The second insulating region 45b is located between the first semiconductor portion 21 and the third electrode 53 in the first direction (X-axis direction). The third insulating region 45c is located between the third electrode 53 and the second semiconductor portion 22 in the first direction.

[0063] 9, the first insulating film 45 may include a fourth insulating region 45d and a fifth insulating region 45e. The first semiconductor portion 21 is located between the fourth partial region 10d and the fourth insulating region 45d in the second direction (Z-axis direction). The second semiconductor portion 22 is located between the fifth partial region 10e and the fifth insulating region 45e in the second direction. For example, the first nitride region 41 is located between the second semiconductor portion 22 and a part of the fifth insulating region 45e.

[0064] (Third embodiment) FIG. 10 is a schematic cross-sectional view illustrating the semiconductor device according to the third embodiment. 10, the semiconductor device 130 according to the embodiment also includes first to third electrodes 51 to 53, a first semiconductor region 10, a second semiconductor region 20, a first conductive member 61, and an insulating member 40. In the semiconductor device 130, the direction from a portion 53a of the third electrode 53 to the first nitride region 41 intersects with the second direction (for example, the Z-axis direction). The configuration described in relation to the first embodiment can be applied to other configurations of the semiconductor device 130.

[0065] For example, in the first direction (X-axis direction), the portion 53a of the third electrode 53 is located between multiple portions of the first nitride region 41. For example, the portion 53a of the third electrode 53 may be in contact with the second semiconductor region 20 (the fourth semiconductor portion 24). The semiconductor device 130 is, for example, a high-frequency transistor.

[0066] FIG. 11 is a schematic cross-sectional view illustrating a semiconductor device according to the third embodiment. 11, the semiconductor device 131 according to the embodiment includes first to third electrodes 51 to 53, a first semiconductor region 10, a second semiconductor region 20, a third semiconductor region 30, a first conductive member 61, and an insulating member 40. The configurations described in relation to the first embodiment can be applied to other components of the semiconductor device 131.

[0067] The third semiconductor region 30 is provided between the fourth semiconductor portion 24 and the third electrode 53. The third semiconductor region 30 is made of Al x3 Ga 1-x3N (0≦x3<1) and a second element. The second element includes at least one selected from the group consisting of Mg and Zn. The third semiconductor region 30 is, for example, a p-type GaN layer. The third semiconductor region 30 is, for example, a p-type AlGaN layer. When the third semiconductor region 30 is a p-type AlGaN layer, the composition ratio x3 is, for example, greater than 0 (for example, 0.05 or more) and 0.5 or less. The semiconductor device 131 is, for example, a JFET transistor.

[0068] The third embodiment also provides a semiconductor device that can stabilize characteristics. The configuration of the semiconductor device according to the third embodiment (semiconductor device 130 or 131) may be applied to the second embodiment.

[0069] In the embodiment, at least one of the first electrode 51 and the second electrode 52 includes at least one selected from the group consisting of, for example, Ti, Al, Cu, and Au. For example, the third electrode 53 (e.g., a gate electrode) includes at least one selected from the group consisting of TiN, WN, Ni, TaN, Ni, Au, Al, Ru, W, and TaSiN. At least one of the first to third conductive members 61 to 63 includes at least one selected from the group consisting of Al, Cu, and Ti.

[0070] In the embodiment, the composition ratio (for example, concentration) of Si and nitrogen is obtained by, for example, Rutherford Backscattering Spectrometry (RBS).

[0071] In the first to third embodiments, the second electrode end 52e of the second electrode 52 contacts the third semiconductor portion 23 (second semiconductor region 20) and the insulating member 40 (for example, the second nitride region 42). The second electrode end 52e corresponds to the end of the portion where the second electrode 52 and the second semiconductor region 20 contact each other, on the third electrode 53 side.

[0072] (Fourth embodiment) FIG. 12 is a schematic cross-sectional view illustrating the semiconductor device according to the fourth embodiment. 12, the semiconductor device 140 according to the embodiment also includes first to third electrodes 51 to 53, a first semiconductor region 10, a second semiconductor region 20, a first conductive member 61, and an insulating member 40. In the semiconductor device 140, the insulating member 40 includes a third nitride region 43. The configurations described in relation to the first embodiment can be applied to other configurations of the semiconductor device 140.

[0073] At least a portion of the second nitride region 42 is located in the first direction (X-axis direction) between at least a portion of the first nitride region 41 and at least a portion of the third nitride region 43. In this example, the second nitride region 42 is located between the first nitride region 41 and the third nitride region 43 in the first direction (X-axis direction).

[0074] The third nitride region 43 contains silicon and nitrogen. A third ratio of the silicon concentration to the nitrogen concentration (Si / N) in the third nitride region 43 is higher than the second ratio. The third nitride region 43 is a region that is even more silicon-rich than the second nitride region 42. Such a third nitride region 43 with a high silicon concentration is provided near the second electrode 52 (for example, the drain electrode). This further suppresses depletion in the vicinity of the second electrode 52. For example, current collapse is more effectively suppressed.

[0075] The third ratio may be greater than 0.96. The third ratio may be any value greater than the second ratio.

[0076] The thickness of the second nitride region 42 along the second direction (Z-axis direction) is defined as thickness t3. In one example, thickness t3 is, for example, 0.5 nm or more and 300 nm or less. For example, a desired threshold voltage is more easily obtained. For example, high gate reliability is more easily obtained. Thickness t3 may be substantially the same as thickness t1 and thickness t2.

[0077] At least a portion of the second nitride region 42 may overlap with a portion of the third nitride region 43. For example, in the Z-axis direction, a portion of the second nitride region 42 may be between the second semiconductor region 20 and a portion of the third nitride region 43. For example, in the Z-axis direction, a portion of the third nitride region 43 may be between the second semiconductor region 20 and a portion of the second nitride region 42.

[0078] In the example of the semiconductor device 140, the second electrode end 52e of the second electrode 52 contacts the third semiconductor portion 23 (second semiconductor region 20) and the insulating member 40 (for example, the third nitride region 43).

[0079] FIG. 13 is a schematic cross-sectional view illustrating the semiconductor device according to the fourth embodiment. 13, the semiconductor device 141 according to the embodiment includes a third conductive member 63. Other configurations of the semiconductor device 141 may be similar to those of the semiconductor device 140.

[0080] The third conductive member 63 is electrically connected to the second electrode 52. Alternatively, the third conductive member 63 can be electrically connected to the second electrode 52. The position of the second electrode 52 in the second direction (Z-axis direction) is between the position of the first semiconductor region 10 in the second direction and the position of the third conductive member 63 in the second direction. At least a portion of the third nitride region 43 overlaps with the third conductive member 63 in the second direction. For example, current collapse is more effectively suppressed.

[0081] According to the embodiment, it is possible to provide a semiconductor device that can stabilize characteristics.

[0082] In this specification, "electrically connected" includes a state in which multiple conductors are physically in contact with each other and a current flows between these multiple conductors. "Electrically connected" also includes a state in which multiple conductors are connected to each other and a current flows between these multiple conductors.

[0083] In this specification, "vertical" and "parallel" do not only mean strictly vertical and strictly parallel, but also include variations in the manufacturing process, and may mean substantially vertical and substantially parallel.

[0084] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configurations of the elements included in the semiconductor device, such as the electrodes, semiconductor regions, conductive members, insulating members, and base, are within the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting them from known ranges.

[0085] Furthermore, any combination of two or more elements of each specific example within the scope of technical feasibility is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0086] In addition, all semiconductor devices that can be implemented by a person skilled in the art by appropriately modifying the design based on the semiconductor device described above as an embodiment of the present invention also fall within the scope of the present invention as long as they include the gist of the present invention.

[0087] In addition, within the scope of the concept of the present invention, a person skilled in the art may come up with various modifications and alterations, and it will be understood that these modifications and alterations also fall within the scope of the present invention.

[0088] Although several 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 embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0089] 10...first semiconductor region, 10C...carrier region, 10a-10f...first to sixth partial regions, 10s...base, 11B...nitride layer, 20...second semiconductor region, 21-24...first to fourth semiconductor portions, 30...third semiconductor region, 40...insulating member, 40p...part, 41-43...first to third nitride regions, 41e...first nitride end, 45...first insulating film, 45a-45e...first to fifth insulating regions, 51-53...first to third electrodes, 52e...second electrode end, 53a...part, 61-63...first to third conductive members, 61e-63e...first to third conductive end, 61G, 61S, 62G, 63D...connecting member, 110, 110a to 110c, 111 to 113, 120, 130, 131, 140, 141...semiconductor device, CC1...resistance increase rate, L1, L2...first and second distances, RL...ratio, t1 to t3...thickness

Claims

1. A first electrode; a second electrode, the direction from the first electrode to the second electrode being along a first direction; a third electrode, the position of the third electrode in the first direction being between the position of the first electrode in the first direction and the position of the second electrode in the first direction; Al ｘ１ Ga １－ｘ１ a first semiconductor region including N (0≦x1<1), the first semiconductor region including a first partial region, a second partial region, a third partial region, a fourth partial region, a fifth partial region, and a sixth partial region, a direction from the first partial region to the first electrode, a direction from the second partial region to the second electrode, and a direction from the third partial region to the third electrode are along a second direction intersecting the first direction, the fourth partial region is between the first partial region and the third partial region in the first direction, the fifth partial region is between the third partial region and the second partial region in the first direction, and the sixth partial region is between the fifth partial region and the second partial region in the first direction; Al ｘ２ Ga １－ｘ２ N (0<x2≦1, x1<x2), the second semiconductor region including a first semiconductor portion, a second semiconductor portion, and a third semiconductor portion, and the direction from the fourth sub-region to the first semiconductor portion is along the second direction; a first conductive member electrically connected to a first one of the first electrode and the third electrode, the first conductive member including a first conductive end in the first direction, the position of the first conductive end in the first direction being between the position of the third electrode in the first direction and the position of the second electrode in the first direction; an insulating member, the insulating member including a first nitride region and a second nitride region, the second semiconductor portion being between the fifth sub-region and the first nitride region in the second direction, the third semiconductor portion being between the sixth sub-region and the second nitride region in the second direction, the first nitride region including silicon and nitrogen, the second nitride region including silicon and nitrogen, a first ratio of a silicon concentration to a nitrogen concentration in the first nitride region being lower than a second ratio of a silicon concentration to a nitrogen concentration in the second nitride region, the first nitride region including a first nitride end, the first nitride end being in contact with the second semiconductor region and facing the second nitride region in the first direction, and a position of the first nitride end in the first direction being between the position of the first conductive end in the first direction and the position of the second electrode in the first direction; Equipped with At least a portion of the first nitride region is between the second semiconductor portion and a portion of the second nitride region in the second direction.

2. The semiconductor device according to claim 1 , wherein said first ratio is less than 0.

75.

3. 3. The semiconductor device according to claim 2, wherein said second ratio is equal to or greater than 0.75 and equal to or less than 0.

96.

4. 4. The semiconductor device according to claim 3, wherein said second ratio is equal to or greater than 0.

78.

5. 5. The semiconductor device according to claim 1, wherein at least a portion of said second nitride region is in contact with said third semiconductor portion.

6. 6. The semiconductor device according to claim 1, wherein a portion of said first nitride region is between said third partial region and said third electrode.

7. A portion of the first nitride region is between the third partial region and the third electrode; 6. The semiconductor device according to claim 1, wherein said third electrode is located between said part of said first nitride region and said part of said second nitride region in said second direction.

8. A first electrode; a second electrode, the direction from the first electrode to the second electrode being along a first direction; a third electrode, the position of the third electrode in the first direction being between the position of the first electrode in the first direction and the position of the second electrode in the first direction; a first semiconductor region including Al x1 Ga 1-x1 N (0≦x1<1), the first semiconductor region including a first partial region, a second partial region, a third partial region, a fourth partial region, a fifth partial region, and a sixth partial region, a direction from the first partial region to the first electrode, a direction from the second partial region to the second electrode, and a direction from the third partial region to the third electrode are along a second direction intersecting with the first direction, the fourth partial region is between the first partial region and the third partial region in the first direction, the fifth partial region is between the third partial region and the second partial region in the first direction, and the sixth partial region is between the fifth partial region and the second partial region in the first direction; a second semiconductor region including Al x2 Ga 1-x2 N (0<x2≦1, x1<x2), the second semiconductor region including a first semiconductor portion, a second semiconductor portion, and a third semiconductor portion, and the direction from the fourth sub-region to the first semiconductor portion is along the second direction; a first conductive member electrically connected to a first one of the first electrode and the third electrode, the first conductive member including a first conductive end in the first direction, the position of the first conductive end in the first direction being between the position of the third electrode in the first direction and the position of the second electrode in the first direction; an insulating member, the insulating member including a first nitride region and a second nitride region, the second semiconductor portion being between the fifth sub-region and the first nitride region in the second direction, the third semiconductor portion being between the sixth sub-region and the second nitride region in the second direction, the first nitride region including silicon and nitrogen, the second nitride region including silicon and nitrogen, a first ratio of a silicon concentration to a nitrogen concentration in the first nitride region being lower than a second ratio of a silicon concentration to a nitrogen concentration in the second nitride region, the first nitride region including a first nitride end, the first nitride end being in contact with the second semiconductor region and facing the second nitride region in the first direction, and a position of the first nitride end in the first direction being between the position of the first conductive end in the first direction and the position of the second electrode in the first direction; Equipped with the insulating member includes a first insulating film including a first insulating region; the first insulating region is provided between the third partial region and the third electrode, the first insulating film contains silicon and oxygen; The semiconductor device, wherein the first insulating film does not contain nitrogen, or the concentration of nitrogen in the first insulating film is lower than the concentration of nitrogen in the second nitride region.

9. A first electrode; a second electrode, the direction from the first electrode to the second electrode being along a first direction; a third electrode, the position of the third electrode in the first direction being between the position of the first electrode in the first direction and the position of the second electrode in the first direction; a first semiconductor region including Al x1 Ga 1-x1 N (0≦x1<1), the first semiconductor region including a first partial region, a second partial region, a third partial region, a fourth partial region, a fifth partial region, and a sixth partial region, a direction from the first partial region to the first electrode, a direction from the second partial region to the second electrode, and a direction from the third partial region to the third electrode are along a second direction intersecting with the first direction, the fourth partial region is between the first partial region and the third partial region in the first direction, the fifth partial region is between the third partial region and the second partial region in the first direction, and the sixth partial region is between the fifth partial region and the second partial region in the first direction; a second semiconductor region including Al x2 Ga 1-x2 N (0<x2≦1, x1<x2), the second semiconductor region including a first semiconductor portion, a second semiconductor portion, and a third semiconductor portion, and the direction from the fourth sub-region to the first semiconductor portion is along the second direction; a first conductive member electrically connected to a first one of the first electrode and the third electrode, the first conductive member including a first conductive end in the first direction, the position of the first conductive end in the first direction being between the position of the third electrode in the first direction and the position of the second electrode in the first direction; an insulating member, the insulating member including a first nitride region and a second nitride region, the second semiconductor portion being between the fifth sub-region and the first nitride region in the second direction, the third semiconductor portion being between the sixth sub-region and the second nitride region in the second direction, the first nitride region including silicon and nitrogen, the second nitride region including silicon and nitrogen, a first ratio of a silicon concentration to a nitrogen concentration in the first nitride region being lower than a second ratio of a silicon concentration to a nitrogen concentration in the second nitride region, the first nitride region including a first nitride end, the first nitride end being in contact with the second semiconductor region and facing the second nitride region in the first direction, and a position of the first nitride end in the first direction being between the position of the first conductive end in the first direction and the position of the second electrode in the first direction; Equipped with at least a portion of the third electrode is located between the first semiconductor portion and the second semiconductor portion in the first direction; the insulating member includes a first insulating film including a first insulating region; the first insulating film further includes a second insulating region and a third insulating region; the second insulating region is located between the first semiconductor portion and the third electrode in the first direction; The semiconductor device, wherein the third insulating region is between the third electrode and the second semiconductor portion in the first direction.

10. the first insulating film further includes a fourth insulating region and a fifth insulating region; the first semiconductor portion is located between the fourth portion region and the fourth insulating region in the second direction; The semiconductor device according to claim 9 , wherein the second semiconductor portion is located between the fifth portion region and the fifth insulating region in the second direction.

11. The semiconductor device of claim 10 , wherein the first nitride region is between the second semiconductor portion and a portion of the fifth insulating region.

12. A first electrode; a second electrode, the direction from the first electrode to the second electrode being along a first direction; a third electrode, the position of the third electrode in the first direction being between the position of the first electrode in the first direction and the position of the second electrode in the first direction; a first semiconductor region including Al x1 Ga 1-x1 N (0≦x1<1), the first semiconductor region including a first partial region, a second partial region, a third partial region, a fourth partial region, a fifth partial region, and a sixth partial region, a direction from the first partial region to the first electrode, a direction from the second partial region to the second electrode, and a direction from the third partial region to the third electrode are along a second direction intersecting with the first direction, the fourth partial region is between the first partial region and the third partial region in the first direction, the fifth partial region is between the third partial region and the second partial region in the first direction, and the sixth partial region is between the fifth partial region and the second partial region in the first direction; a second semiconductor region including Al x2 Ga 1-x2 N (0<x2≦1, x1<x2), the second semiconductor region including a first semiconductor portion, a second semiconductor portion, and a third semiconductor portion, and the direction from the fourth sub-region to the first semiconductor portion is along the second direction; a first conductive member electrically connected to a first one of the first electrode and the third electrode, the first conductive member including a first conductive end in the first direction, the position of the first conductive end in the first direction being between the position of the third electrode in the first direction and the position of the second electrode in the first direction; an insulating member, the insulating member including a first nitride region and a second nitride region, the second semiconductor portion being between the fifth sub-region and the first nitride region in the second direction, the third semiconductor portion being between the sixth sub-region and the second nitride region in the second direction, the first nitride region including silicon and nitrogen, the second nitride region including silicon and nitrogen, a first ratio of a silicon concentration to a nitrogen concentration in the first nitride region being lower than a second ratio of a silicon concentration to a nitrogen concentration in the second nitride region, the first nitride region including a first nitride end, the first nitride end being in contact with the second semiconductor region and facing the second nitride region in the first direction, and a position of the first nitride end in the first direction being between the position of the first conductive end in the first direction and the position of the second electrode in the first direction; A second conductive member; Equipped with the second conductive member is electrically connected to a second one of the first electrode and the third electrode; the second conductive member includes a second conductive end portion in the first direction, a position of the second conductive end in the first direction between the position of the third electrode in the first direction and the position of the first conductive end in the first direction;

13. 13 . The semiconductor device according to claim 12 , wherein a position of said second conductive member in said second direction is between a position of said third electrode in said second direction and a position of said first conductive member in said second direction.

14. A first electrode; a second electrode, the direction from the first electrode to the second electrode being along a first direction; a third electrode, the position of the third electrode in the first direction being between the position of the first electrode in the first direction and the position of the second electrode in the first direction; a first semiconductor region including Al x1 Ga 1-x1 N (0≦x1<1), the first semiconductor region including a first partial region, a second partial region, a third partial region, a fourth partial region, a fifth partial region, and a sixth partial region, a direction from the first partial region to the first electrode, a direction from the second partial region to the second electrode, and a direction from the third partial region to the third electrode are along a second direction intersecting with the first direction, the fourth partial region is between the first partial region and the third partial region in the first direction, the fifth partial region is between the third partial region and the second partial region in the first direction, and the sixth partial region is between the fifth partial region and the second partial region in the first direction; a second semiconductor region including Al x2 Ga 1-x2 N (0<x2≦1, x1<x2), the second semiconductor region including a first semiconductor portion, a second semiconductor portion, and a third semiconductor portion, and the direction from the fourth sub-region to the first semiconductor portion is along the second direction; a first conductive member electrically connected to a first one of the first electrode and the third electrode, the first conductive member including a first conductive end in the first direction, the position of the first conductive end in the first direction being between the position of the third electrode in the first direction and the position of the second electrode in the first direction; an insulating member, the insulating member including a first nitride region and a second nitride region, the second semiconductor portion being between the fifth sub-region and the first nitride region in the second direction, the third semiconductor portion being between the sixth sub-region and the second nitride region in the second direction, the first nitride region including silicon and nitrogen, the second nitride region including silicon and nitrogen, a first ratio of a silicon concentration to a nitrogen concentration in the first nitride region being lower than a second ratio of a silicon concentration to a nitrogen concentration in the second nitride region, the first nitride region including a first nitride end, the first nitride end being in contact with the second semiconductor region and facing the second nitride region in the first direction, and a position of the first nitride end in the first direction being between the position of the first conductive end in the first direction and the position of the second electrode in the first direction; a third conductive member; Equipped with the third conductive member is electrically connected to the second electrode; the third conductive member includes a third conductive end portion in the first direction, A semiconductor device, wherein the position of the first nitride end in the first direction is between the position of the first conductive end in the first direction and the position of the third conductive end in the first direction.

15. the second electrode includes a second electrode end; the second electrode end portion is in contact with the third semiconductor portion and the insulating member, A semiconductor device according to any one of claims 1 to 14, wherein a first distance along the first direction between the position of the first conductive end in the first direction and the position of the first nitride end in the first direction is 0.43 times or more of a second distance along the first direction between the position of the first conductive end in the first direction and the position of the second electrode end in the first direction.

16. a thickness of the first nitride region along the second direction is 0.5 nm or more and 300 nm or less; 16. The semiconductor device according to claim 1, wherein the thickness of said second nitride region along said second direction is not less than 0.5 nm and not more than 300 nm.

17. the insulating member further comprises a third nitride region; at least a portion of the second nitride region is between at least a portion of the first nitride region and at least a portion of the third nitride region in the first direction; the third nitride region comprises silicon and nitrogen; a third ratio of the concentration of silicon to the concentration of nitrogen in the third nitride region is greater than the second ratio; Further comprising a third conductive member; the third conductive member is electrically connected to the second electrode; a position of the second electrode in the second direction is between a position of the first semiconductor region in the second direction and a position of the third conductive member in the second direction; 5. The semiconductor device according to claim 1, wherein at least a portion of said third nitride region overlaps with said third conductive member in said second direction.

18. The semiconductor device of claim 17 , wherein the third ratio is greater than 0.96.

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