阅读说明：本技术 Ga2O3系半导体元件 (Ga2O3 semiconductor device ) 是由 东胁正高 中田义昭 上村崇史 黄文海 佐佐木公平 胁本大树 于 2018-04-26 设计创作，主要内容包括：作为一个实施方式,提供一种Ga<Sub>2</Sub>O<Sub>3</Sub>系半导体元件(1a),Ga<Sub>2</Sub>O<Sub>3</Sub>系半导体元件(1a)具有：第二Ga<Sub>2</Sub>O<Sub>3</Sub>系晶体层(11),其包含施主；以及N添加区域,其形成于整个第二Ga<Sub>2</Sub>O<Sub>3</Sub>系晶体层(11)。(As an embodiment, there is provided Ga 2 O 3 Is a semiconductor element (1a), Ga 2 O 3 The semiconductor device (1a) comprises: second Ga 2 O 3 A system crystal layer (11) containing a donor; and an N-added region formed over the entire second Ga 2 O 3 A crystal-containing layer (11).)

1. Ga₂O₃The semiconductor device is characterized by comprising:

Ga₂O₃a crystal-based layer including a donor; and

an N-doped region formed in the Ga₂O₃At least a portion of the crystalline layer.

2. Ga according to claim 1₂O₃Is a semiconductor device, which is a semiconductor device,

the N addition region contains N at a higher concentration than the donor.

3. Ga according to claim 1 or 2₂O₃Is a semiconductor device, which is a semiconductor device,

the N-doped region is formed in the Ga₂O₃Is a portion of the crystalline layer.

4. Ga according to claim 1₂O₃Is a semiconductor device, which is a semiconductor device,

the donor is added to Ga unintentionally₂O₃A donor of the system crystal layer,

the N addition region contains N at a concentration equal to or less than the donor concentration.

5. The method of any one of claims 1, 2, or 4Ga of (2)₂O₃Is a semiconductor device, which is a semiconductor device,

which acts as a vertical schottky barrier diode,

the N adding area is a current path or a guard ring.

6. Ga according to claim 1 or 2₂O₃Is a semiconductor device, which is a semiconductor device,

which is used as a vertical MOSFET,

the N-doped region includes a channel region, or the N-doped region is a current blocking region having an opening region to be a current path.

7. Ga according to any one of claims 1, 2 and 4₂O₃Is a semiconductor device, which is a semiconductor device,

which is used as a lateral type MOSFET,

the N-doped region includes a channel region, or the N-doped region is located in the Ga₂O₃Channel region in the system crystal layer and the Ga₂O₃Between the bottom surfaces of the series crystal layers.

8. Ga according to any one of claims 1, 2 and 4₂O₃Is a semiconductor device, which is a semiconductor device,

which is used as a MESFET and is,

the N-doped region includes a channel region, or the N-doped region is located in the Ga₂O₃Channel region in the system crystal layer and the Ga₂O₃Between the bottom surfaces of the series crystal layers.

Technical Field

The present invention relates to Ga₂O₃Is a semiconductor device.

Background

Conventionally, it has been known to use undoped (not intentionally doped) Ga₂O₃A crystalline film in Ga₂O₃Is a technique of epitaxial growth on a substrate (for example, see patent document 1).

In addition, a semiconductor device is known, which includes: base substrate comprising Ga₂O₃Is crystalline; a buffer layer epitaxially grown on the base substrate and comprising undoped Ga₂O₃Is crystalline; and Ga on the buffer layer₂O₃A system crystal layer to which Si is added as a dopant (see, for example, non-patent document 1).

Disclosure of Invention

Problems to be solved by the invention

In the presence of Ga₂O₃When a crystalline film is epitaxially grown without doping, unexpected donors may be generated and the film may become n-type. If such undoped Ga is to be used₂O₃When a crystalline film is used in a semiconductor device, undoped Ga may be generated₂O₃The problem caused by the n-type crystal film.

For example, undoped Ga is used for the buffer layer₂O₃In a Field Effect Transistor (FET) having a crystal film, a current (leakage current) flows through a buffer layer in addition to a current flowing through a channel layer, and thus the FET cannot normally operate.

Therefore, it is sometimes required to add a suitable acceptor to undoped Ga₂O₃The system crystal layer compensates for the donor which is not intentionally added, thereby increasing the resistance. In addition, if it is in Ga₂O₃Impurities in the system crystal layer that function as acceptors can also be used for undoped Ga₂O₃Of crystalline or n-type undoped Ga₂O₃Formation of a p-type region in the system crystal layer.

An object of the present invention is to provide Ga having a novel acceptor impurity added thereto₂O₃Ga of system crystal layer₂O₃Is a semiconductor device.

Means for solving the problems

In order to achieve the above object, one aspect of the present invention provides the following [1 ]]～[8]Ga of (2)₂O₃Is a semiconductor device.

[1]Ga₂O₃A semiconductor device, comprising: ga₂O₃A crystal-based layer including a donor; and an N (nitrogen) -added region formed in the Ga₂O₃At least a portion of the crystalline layer.

[2]According to the above [1]Said Ga being₂O₃The N-doped region includes N at a concentration higher than the donor concentration.

[3]According to the above [1]Or [2 ]]Said Ga being₂O₃The N-doped region is formed in the Ga₂O₃Is a portion of the crystalline layer.

[4]According to the above [1]Said Ga being₂O₃A semiconductor element in which the donor is added to the Ga unintentionally₂O₃The N-added region contains N at a concentration equal to or less than the concentration of the donor.

[5]According to the above [1]、[2]、[4]Ga as described in any one of₂O₃The semiconductor device is a vertical Schottky barrier diode, and the N-added region is a current path or a guard ring.

[6]According to the above [1]Or [2 ]]Said Ga being₂O₃The N-doped region includes a channel region, or the N-doped region is a current blocking region having an opening region serving as a current path.

[7]According to the above [1]、[2]、[4]Any one ofGa of (2)₂O₃A semiconductor device as a lateral MOSFET, wherein the N-doped region includes a channel region or is located in the Ga region₂O₃Channel region in the system crystal layer and the Ga₂O₃Between the bottom surfaces of the series crystal layers.

[8]According to the above [1]、[2]、[4]Ga as described in any one of₂O₃A semiconductor device as a MESFET, wherein the N-doped region includes a channel region, or the N-doped region is located in the Ga₂O₃Channel region in the system crystal layer and the Ga₂O₃Between the bottom surfaces of the series crystal layers.

Effects of the invention

According to the present invention, Ga having a novel acceptor impurity added thereto can be provided₂O₃Ga of system crystal layer₂O₃Is a semiconductor device.

Drawings

Fig. 1 is a vertical sectional view of a schottky barrier diode according to a first embodiment.

Fig. 2 is a vertical sectional view of the schottky barrier diode of the first embodiment.

Fig. 3 is a vertical sectional view of the schottky barrier diode of the first embodiment.

Fig. 4 is a vertical cross-sectional view of a vertical MOSFET of the second embodiment.

Fig. 5 is a vertical cross-sectional view of a vertical MOSFET according to a second embodiment.

Fig. 6 is a vertical cross-sectional view of a vertical MOSFET of the second embodiment.

Fig. 7 is a vertical cross-sectional view of a lateral MOSFET according to a third embodiment.

Fig. 8 is a vertical cross-sectional view of a lateral MOSFET according to a third embodiment.

Fig. 9 is a vertical cross-sectional view of a lateral MOSFET according to a third embodiment.

Fig. 10 is a vertical cross-sectional view of a lateral MOSFET according to a third embodiment.

Fig. 11 is a vertical cross-sectional view of a MESFET of the fourth embodiment.

Fig. 12 is a vertical cross-sectional view of a MESFET of the fourth embodiment.

FIG. 13 is a vertical sectional view of a sample used in the experiment of example 1.

Fig. 14 is a graph showing the leakage characteristics of the measured sample.

FIG. 15A shows a second Ga₂O₃O used for growth of crystal-based layer₂And N₂N in the mixed gas of₂Second Ga at a gas concentration of 0 vol%₂O₃SIMS distribution of N in the system crystal layer.

FIG. 15B is a view of second Ga₂O₃O used for growth of crystal-based layer₂And N₂N in the mixed gas of₂Second Ga in a gas concentration of 0.04 vol%₂O₃SIMS distribution of N in the system crystal layer.

FIG. 15C is a drawing of a second Ga₂O₃O used for growth of crystal-based layer₂And N₂N in the mixed gas of₂Second Ga in a gas concentration of 0.4 vol%₂O₃SIMS distribution of N in the system crystal layer.

FIG. 16A shows a second Ga₂O₃O used for growth of crystal-based layer₂And N₂N in the mixed gas of₂A graph of the conductive characteristics of the schottky barrier diode at a gas concentration of 0 vol%.

FIG. 16B shows a second Ga₂O₃O used for growth of crystal-based layer₂And N₂N in the mixed gas of₂A graph of the conductivity characteristics of the schottky barrier diode at a gas concentration of 0.04 vol%.

FIG. 16C shows a second Ga₂O₃O used for growth of crystal-based layer₂And N₂N in the mixed gas of₂A graph of the conductivity characteristics of the schottky barrier diode at a gas concentration of 0.4 vol%.

FIG. 17 shows a second Ga₂O₃Growth station of crystal system layerO used₂And N₂N in the mixed gas of₂And a graph showing a relationship between the concentration of the gas and the forward current density when the anode voltage of the schottky barrier diode is 6V.

Detailed Description

[ first embodiment ]

The first embodiment is a semiconductor device having Ga with N addition region₂O₃A Schottky barrier diode of a crystal layer.

It has not been known that N (nitrogen) is doped into Ga at a concentration at which the characteristics are affected₂O₃In the system crystal, it is not known that N is present in Ga₂O₃The crystal system functions as an acceptor.

Here, Ga is₂O₃Is a single crystal of Ga₂O₃Single crystal or Ga containing Al, In and the like₂O₃And (3) single crystal. For example, Ga to which Al and In are added may be used₂O₃Of single crystal (Ga)_xAl_yIn_(1-x-y))₂O₃(x is more than 0 and less than or equal to 1, y is more than or equal to 0 and less than 1, and x + y is more than 0 and less than or equal to 1). When Al is added, the band gap becomes wider, and when In is added, the band gap becomes narrower.

Fig. 1 is a vertical sectional view of a schottky barrier diode 1a according to the first embodiment.

The schottky barrier diode 1a is a vertical schottky barrier diode, and includes: first Ga₂O₃A system crystal layer 10; second Ga₂O₃A system crystal layer 11 laminated on the first Ga₂O₃A system crystal layer 10; an anode electrode 12 connected to the second Ga₂O₃A system crystal layer 11; and a cathode electrode 13 connected to the first Ga₂O₃A crystal layer 10.

First Ga₂O₃The system crystal layer 10 includes n containing a donor group IV element such as Si or Sn⁺Form Ga₂O₃Is a single crystal. First Ga₂O₃Donor concentration of the system crystal layer 10, for exampleIs 1 × 10¹⁷～1×10²⁰cm^-3. First Ga₂O₃The thickness of the crystal layer 10 is, for example, 0.5 to 1000 μm.

In a typical structure of the schottky barrier diode 1a, the first Ga₂O₃The system crystal layer 10 is Ga₂O₃Is a substrate. First Ga₂O₃The plane orientations of the main surfaces of the main crystal layer 10 are, for example, (010), (001), and (-201).

Second Ga₂O₃The system crystal layer 11 is in the first Ga₂O₃The layer formed by epitaxial crystal growth on the system crystal layer 10 includes Ga containing donor which is not intentionally added₂O₃Is a single crystal. Here, the donor which is not intentionally added includes defects such as oxygen vacancies in addition to impurities. The concentration of the donor to be added unintentionally is, for example, 1X 10¹⁸cm^-3The following. Second Ga₂O₃The thickness of the crystal-based layer 11 is, for example, 0.1 to 100 μm.

In addition, in the second Ga₂O₃In the system crystal layer 11, N is intentionally added to compensate for the donor which is unintentionally added. In order to reduce the electron concentration, the second Ga is preferred₂O₃The N concentration of the system crystal layer 11 is equal to or less than the donor concentration which is not intentionally added. N is a radical of a second Ga₂O₃The crystal growth of the system crystal layer 11 is added in parallel (in-situ doping), the whole second Ga₂O₃The system crystal layer 11 is an N-doped region. In addition, when a group IV element such as Si or Sn is intentionally added together with N, the concentration of N may be higher than that of a donor which is not intentionally added.

Second Ga₂O₃The system crystal layer 11 is formed by using, for example, Ga metal and O₂And N₂The mixed gas of (3) is used as a raw material, and is formed by a molecular beam epitaxy method (MBE method) using an ozone gas.

The anode electrode 12 has, for example, a Pt/Ti/Au laminated structure, and second Ga₂O₃The system crystal layer 11 is in Schottky contact.

The cathode electrode 13 has, for example, a Ti/Au laminated junctionStructure of, and first Ga₂O₃The system crystal layer 10 is in ohmic contact.

In the schottky barrier diode 1a, a forward voltage is applied between the anode electrode 12 and the cathode electrode 13 (positive potential is applied to the anode electrode 12 side), and the second Ga is converted from the second Ga₂O₃An anode electrode 12 and a second Ga as viewed from a system crystal layer 11₂O₃The energy barrier between the system crystal layers 11 is lowered, and a current flows from the anode electrode 12 to the cathode electrode 13. Therefore, the second Ga is entirely the N-added region₂O₃The main crystal layer 11 serves as a current path. On the other hand, when a reverse voltage is applied between the anode electrode 12 and the cathode electrode 13 (the anode electrode 12 side is a negative potential), the flow of current is blocked by the schottky barrier.

Fig. 2 is a vertical sectional view of the schottky barrier diode 1b of the first embodiment. The schottky barrier diode 1b is different from the schottky barrier diode 1a in that it has a field plate structure.

In the Schottky barrier diode 1b, the second Ga is₂O₃On the upper surface of the system crystal layer 11, SiO is provided along the periphery of the anode electrode 16₂And an insulating film 14, and the edge of the anode electrode 16 is laid on the insulating film 14.

By providing such a field plate structure, concentration of an electric field to the end portion of the anode electrode 16 can be suppressed. In addition, the insulating film 14 also serves to suppress the second Ga₂O₃The passivation film of the surface leakage current flowing on the upper surface of the system crystal layer 11 functions.

Fig. 3 is a vertical sectional view of the schottky barrier diode 1c of the first embodiment.

The schottky barrier diode 1c is different from the schottky barrier diode 1b in that it has a guard ring structure. In the Schottky barrier diode 1c, the second Ga is₂O₃An N-added region 101 as a guard ring is formed near the upper surface of the system crystal layer 15. I.e. in the second Ga₂O₃An N-doped region 101 is formed in a part of the system crystal layer 15.

Second Ga₂O₃The system crystal layer 15 includesN containing a donor group IV element such as Si or Sn^-Form Ga₂O₃Is a single crystal. Second Ga₂O₃The donor concentration of the system crystal layer 15 is, for example, 1X 10¹⁸cm^-3The following. Second Ga₂O₃The thickness of the crystal layer 15 is, for example, 0.1 to 100 μm.

The N addition region 101 is formed by selectively adding the second Ga to the second Ga, for example₂O₃The upper surface of the system crystal layer 15 is formed by performing N ion implantation in a region partially overlapping the anode electrode 16. The N concentration of the N addition region 101 is higher than that of the second Ga₂O₃Donor concentration of the system crystal layer 15. By providing such a guard ring structure, the electric field concentration at the end of the anode electrode 16 can be alleviated.

[ second embodiment ]

The second embodiment is a semiconductor device having Ga with N addition region₂O₃A vertical MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) of a crystal layer.

Fig. 4 is a vertical cross-sectional view of a vertical MOSFET2a of the second embodiment.

The vertical MOSFET2a includes: first Ga₂O₃A system crystal layer 20; second Ga₂O₃A system crystal layer 21 laminated on the first Ga₂O₃A system crystal layer 20; a gate electrode 24 formed on the second Ga with a gate insulating film 25 interposed therebetween₂O₃On the system crystal layer 21; n is⁺A region 202 formed in the second Ga₂O₃Both sides of gate electrode 24 near the upper surface of system crystal layer 21; p is a radical of⁺Region 203 formed at n⁺Outside of region 202; an N-added region 201 surrounding N⁺Regions 202 and p⁺A region 203; a source electrode 22 formed on the second Ga₂O₃On the system crystal layer 21, connected to n⁺Regions 202 and p⁺A region 203; and a drain electrode 23 formed on the first Ga₂O₃Of the system crystal layer 20 and second Ga₂O₃On the opposite side of the system crystal layer 21.

The vertical MOSFET2a is an enhancement (normally off) vertical MOSFET. When a voltage equal to or higher than a threshold value is applied to the gate electrode 24, an inversion-type channel is formed in the N addition region 201 below the gate electrode 24, and a current flows from the drain electrode 23 to the source electrode 22. That is, the N addition region 201 includes a channel region (a region where a channel is formed).

First Ga₂O₃The system crystal layer 20 contains n containing a group IV element such as Si or Sn serving as a donor⁺Form Ga₂O₃Is a single crystal. First Ga₂O₃The donor concentration of the system crystal layer 20 is, for example, 1X 10¹⁷～1×10²⁰cm^-3. First Ga₂O₃The thickness of the crystal layer 20 is, for example, 0.5 to 1000 μm.

In a typical configuration of the vertical MOSFET2a, the first Ga₂O₃The system crystal layer 20 is Ga₂O₃Is a substrate. First Ga₂O₃The plane orientations of the main surfaces of the main crystal layer 10 are, for example, (010), (001), and (-201).

Second Ga₂O₃The system crystal layer 21 contains n containing a group IV element such as Si or Sn serving as a donor^-Form Ga₂O₃Is a single crystal. Second Ga₂O₃The donor concentration of the system crystal layer 21 is, for example, 1X 10¹⁸cm^-3The following. Second Ga₂O₃The thickness of the crystal layer 21 is, for example, 1 to 100 μm.

The source electrode 22, the drain electrode 23, and the gate electrode 24 include, for example, Ti/Au. The gate insulating film 25 comprises SiO₂Etc. insulating material.

n⁺The region 202 is in the second Ga₂O₃The region of the system crystal layer 21 where the n-type dopant concentration is high is formed by ion implantation or the like. p is a radical of⁺Region 203 is in the second Ga₂O₃The p-type dopant concentration in the region of the p-type crystal layer 21 is high due to implantation of a p-type material, ion implantation, or the like.

The N-doped region 201 is formed by ion implantation or the like in the surrounding N⁺Regions 202 and p⁺The region 203. I.e. in the second Ga₂O₃An N-doped region 201 is formed in a part of the system crystal layer 21. The N concentration of the N addition region 201 is higher than that of the second Ga₂O₃A crystal layer 21 (n)⁺Regions 202 and p⁺Regions other than region 203).

Fig. 5 is a vertical cross-sectional view of a vertical MOSFET2b of the second embodiment. The vertical MOSFET2b has a gate electrode buried in the second Ga₂O₃This is different from the vertical MOSFET2a in the trench type vertical MOSFET of the crystal layer.

In the vertical MOSFET2b, the gate electrode 26 is covered with the gate insulating film 27 and embedded in the second Ga₂O₃A system crystal layer 21, N addition regions 201, N⁺Regions 202 and p⁺Regions 203 are located on both sides of gate electrode 26.

Vertical MOSFET2b is an enhancement type vertical MOSFET. When a voltage equal to or higher than a threshold value is applied to the gate electrode 26, an inversion channel is formed in the N addition region 201 on the side of the gate electrode 26, and a current flows from the drain electrode 23 to the source electrode 22. That is, the N addition region 201 includes a channel region.

Fig. 6 is a vertical cross-sectional view of a vertical MOSFET2c of the second embodiment. The vertical MOSFET2c is a depletion type (normally on) vertical MOSFET having a current blocking layer formed therein, and is different from the vertical MOSFET2 a.

In the vertical MOSFET2c, the second Ga is₂O₃N is formed on both sides of gate electrode 24 near the upper surface of system crystal layer 21⁺Region 205 in the second Ga₂O₃N in the system crystal layer 21⁺An N-added region 204, which is a current blocking region having an open region, is formed in a portion below the region 205.

n⁺Region 205 is in the second Ga₂O₃The region of the system crystal layer 21 where the n-type dopant concentration is high is formed by ion implantation or the like.

The N-added region 204 is formed in N by ion implantation or the like⁺A portion below region 205. A region 204a surrounded by the N addition region 204 and located below the gate electrode 24 is an opening region of the current blocking regionWhich becomes the region of the current path. I.e. in the second Ga₂O₃An N-doped region 204 is formed in a part of the system crystal layer 21. The N concentration of the N addition region 204 is higher than that of the second Ga₂O₃A crystal layer 21 (n)⁺Regions other than region 205).

As described above, the vertical MOSFET2c is a depletion type vertical MOSFET. While a current can flow from the drain electrode 23 to the source electrode 22 in a state where no voltage is applied to the gate electrode 24 or in a state where a voltage equal to or higher than a threshold value is applied, a part of the channel is turned off when a voltage equal to or lower than a threshold value is applied to the gate electrode 24, and as a result, the current can be turned off.

[ third embodiment ]

The third embodiment is a semiconductor device having Ga with N addition region₂O₃A lateral MOSFET system.

Fig. 7 is a vertical cross-sectional view of a lateral MOSFET3a of the third embodiment.

The lateral MOSFET3a includes: first Ga₂O₃A system crystal layer 30; second Ga₂O₃A system crystal layer 31 laminated on the first Ga₂O₃A system crystal layer 30; a source electrode 32 and a drain electrode 33 formed on the second Ga₂O₃On the system crystal layer 31; a gate electrode 34 formed on the second Ga between the source electrode 32 and the drain electrode 33 via a gate insulating film 35₂O₃A region on the seed crystal layer 31; n is⁺A region 302 formed in the second Ga₂O₃Both sides of the gate electrode 34 near the upper surface of the system crystal layer 31 are connected to the source electrode 32 and the drain electrode 33, respectively; and an N addition region 301 in the second Ga₂O₃N in the system crystal layer 31⁺Region 302 and first Ga₂O₃The series crystal layers 30 are continuously formed in the in-plane direction.

The lateral MOSFET3a is a depletion-type lateral MOSFET. When no voltage is applied to the gate electrode 34, a current can flow from the drain electrode 33 to the source electrode 32, but when a threshold value or less is applied to the gate electrode 34At voltage, the depletion layer will expand and 2 n⁺The channel between the regions 302 narrows and the flow of current is impeded.

First Ga₂O₃The system crystal layer 30 is a semi-insulating layer to which acceptor impurities such as Fe having a concentration higher than the donor concentration are intentionally added. First Ga₂O₃The resistivity of the system crystal layer 30 is, for example, 1X 10¹⁰Omega cm or more. First Ga₂O₃The thickness of the crystal-based layer 30 is, for example, 0.5 to 1000 μm.

In a typical configuration of the lateral MOSFET3a, the first Ga₂O₃The system crystal layer 30 is Ga₂O₃Is a substrate. First Ga₂O₃The plane orientations of the main surfaces of the main crystal layer 30 are, for example, (010), (001), and (-201).

Second Ga₂O₃The system crystal layer 31 includes n containing a donor group IV element such as Si or Sn^-Form Ga₂O₃Is a single crystal. Second Ga₂O₃The donor concentration of the system crystal layer 31 is, for example, 1X 10¹⁶～5×10¹⁹cm^-3. Second Ga₂O₃The thickness of the system crystal layer 31 is, for example, 0.02 to 100 μm.

The source electrode 32, the drain electrode 33, and the gate electrode 34 include, for example, Ti/Au. The gate insulating film 35 includes SiO₂Etc. insulating material.

n⁺Region 302 is in the second Ga₂O₃The region of the system crystal layer 31 where the n-type dopant concentration is high is formed by ion implantation or the like.

The N addition region 301 is formed by ion implantation or the like at a position that blocks a space between: formed at 2 n⁺Channels between the regions 302; and a second Ga₂O₃A system crystal layer 31 and a first Ga₂O₃Is the interface of the crystal layer 30. That is, the N addition region 301 is formed in the second Ga₂O₃A part of the system crystal layer 31, a second Ga₂O₃Channel region in the system crystal layer 31 and the second Ga₂O₃Between the bottom surfaces of the series crystal layers 31. Therefore, the N addition region 301 can be suppressed to the secondGa₂O₃A system crystal layer 31 and a first Ga₂O₃A leakage current flowing through the interface of the crystal layer 30. The N concentration of the N addition region 301 is higher than that of the second Ga₂O₃A crystal layer 31 (n)⁺Regions other than region 302).

Fig. 8 is a vertical sectional view of a lateral MOSFET3b of the third embodiment. In the lateral MOSFET3b, the second Ga is entirely filled with₂O₃Unlike the lateral MOSFET3a, the system crystal layer has an N-added region.

Second Ga of lateral MOSFET3b₂O₃The system crystal layer 36 is in the first Ga₂O₃The layer formed by epitaxial crystal growth on the system crystal layer 30 includes Ga containing an unintentionally added donor₂O₃Is a single crystal. The concentration of the donor to be added unintentionally is, for example, 1X 10¹⁸cm^-3The following. Second Ga₂O₃The thickness of the crystal-based layer 36 is, for example, 0.02 to 100 μm.

In addition, in the second Ga₂O₃In the system crystal layer 36, N is intentionally added to compensate for the donor which is unintentionally added. In order to reduce the electron concentration, the second Ga is preferred₂O₃The N concentration of the system crystal layer 36 is equal to or less than the donor concentration which is not intentionally added. N is a radical of a second Ga₂O₃The crystal growth of the system crystal layer 36 is added in parallel, and the entire second Ga is added₂O₃The main crystal layer 36 is an N-doped region. Further, N may be added to the second Ga by ion implantation₂O₃A crystal layer 36. In addition, when a group IV element such as Si or Sn is intentionally added together with N, the N concentration may be higher than the donor concentration which is not intentionally added.

The lateral MOSFET3b is a depletion-type lateral MOSFET. While current can flow from the drain electrode 33 to the source electrode 32 in a state where no voltage is applied to the gate electrode 34, when a voltage equal to or lower than a threshold value is applied to the gate electrode 34, a depletion layer expands and 2 n depletion layers are formed⁺The channel between the regions 302 narrows and the flow of current is impeded. I.e. over the entire second Ga₂O₃The N added region formed in the system crystal layer 36 includes a channel region.

Fig. 9 is a vertical sectional view of a lateral MOSFET3c of the third embodiment. Unlike the lateral MOSFET3b, the lateral MOSFET3c is an enhancement type.

Second Ga of lateral MOSFET3c₂O₃The system crystal layer 37 is in the first Ga₂O₃The layer formed by epitaxial crystal growth on the system crystal layer 30 includes Ga containing an unintentionally added donor₂O₃Is a single crystal. The concentration of the donor to be added unintentionally is, for example, 1X 10¹⁸cm^-3The following. Second Ga₂O₃The thickness of the system crystal layer 37 is, for example, 0.02 to 100 μm.

In addition, in the second Ga₂O₃In the system crystal layer 37, N is intentionally added to compensate for the donor which is unintentionally added. Preferably the second Ga₂O₃The N concentration of the system crystal layer 37 is larger than the concentration of the donor which is not intentionally added. N is a radical of a second Ga₂O₃The crystal growth of the system crystal layer 37 is added in parallel, and the whole second Ga₂O₃The main crystal layer 37 becomes an N-added region. Further, N may be added to the second Ga by ion implantation₂O₃A crystal layer 37.

The gate electrode 38 of the lateral MOSFET3c is n-th to form a continuous channel region between the source electrode 32 and the drain electrode 33⁺The ends of the region 302 overlap or are in close proximity.

Lateral MOSFET3c is an enhancement lateral MOSFET. When a voltage of not less than a threshold value is applied to the gate electrode 38, the second Ga is present₂O₃2 n near the upper surface of the system crystal layer 37⁺A channel is formed between the regions 302, and a current flows from the drain electrode 33 to the source electrode 32. I.e. over the entire second Ga₂O₃The N-added region formed in the system crystal layer 37 includes a channel region.

Fig. 10 is a vertical cross-sectional view of a lateral MOSFET3d of the third embodiment. In the lateral MOSFET3d, the N addition region is formed only in the second Ga₂O₃A part of the upper side of the system crystal layerThis is different from the lateral MOSFET3 c.

The N addition region 303 of the lateral MOSFET3d is formed in the second Ga by ion implantation or the like₂O₃N is contained in the upper part of the system crystal layer 31⁺The area of area 302. I.e. in the second Ga₂O₃An N-doped region 303 is formed in a part of the system crystal layer 31. The N concentration of the N addition region 303 is higher than that of the second Ga₂O₃A crystal layer 31 (n)⁺Regions other than region 302).

Like the lateral MOSFET3c, the lateral MOSFET3d is an enhancement-type lateral MOSFET. When a voltage of not less than a threshold value is applied to the gate electrode 38, the second Ga is present₂O₃2N pieces near the upper surface of the system crystal layer 31 (N-added region 303)⁺A channel is formed between the regions 302, and a current flows from the drain electrode 33 to the source electrode 32. That is, the N addition region 303 includes a channel region.

[ fourth embodiment ]

The fourth embodiment is a semiconductor device having Ga with N addition region₂O₃A MESFET (Metal-Semiconductor Field Effect Transistor) type crystal layer.

Fig. 11 is a vertical cross-sectional view of MESFET4a of the fourth embodiment.

The MESFET4a has: first Ga₂O₃A system crystal layer 40; second Ga₂O₃A system crystal layer 41 laminated on the first Ga₂O₃A system crystal layer 40; a source electrode 42 and a drain electrode 43 formed on the second Ga₂O₃On the system crystal layer 41; a gate electrode 44 formed on the second Ga between the source electrode 42 and the drain electrode 43₂O₃A region on the seed crystal layer 41; n is⁺A region 402 formed in the second Ga₂O₃Both sides of the gate electrode 44 near the upper surface of the system crystal layer 41 are connected to the source electrode 42 and the drain electrode 43, respectively; and an N addition region 401 in the second Ga₂O₃N in the system crystal layer 41⁺Region 402 and first Ga₂O₃A crystal system layer 40 are continuously formed in the in-plane direction.

Gate electrode 44 and second Ga₂O₃Schottky contact is made on the upper surface of the system crystal layer 41, and the second Ga is₂O₃A depletion layer is formed below the gate electrode 44 in the system crystal layer 41. The MESFET4a functions as a depletion transistor or an enhancement transistor according to the thickness of the depletion region.

First Ga₂O₃The system crystal layer 40 is a semi-insulating layer to which acceptor impurities such as Fe having a concentration higher than the donor concentration are intentionally added. First Ga₂O₃The resistivity of the system crystal layer 40 is, for example, 1X 10¹⁰Omega cm or more. First Ga₂O₃The thickness of the crystal-based layer 40 is, for example, 0.5 to 1000 μm.

In a typical configuration of MESFET4a, the first Ga₂O₃The system crystal layer 40 is Ga₂O₃Is a substrate. First Ga₂O₃The plane orientations of the main surfaces of the main crystal layer 40 are, for example, (010), (001), and (-201).

Second Ga₂O₃The system crystal layer 41 contains n containing a group IV element such as Si or Sn serving as a donor^-Form Ga₂O₃Is a single crystal. Second Ga₂O₃The donor concentration of the system crystal layer 41 is, for example, 1X 10¹⁶～5×10¹⁹cm^-3. Second Ga₂O₃The thickness of the system crystal layer 41 is, for example, 0.02 to 100 μm.

The source electrode 42 and the drain electrode 43 include, for example, Ti/Au. The gate electrode 44 includes, for example, Pt/Ti/Au.

n⁺Region 402 is in the second Ga₂O₃The region of the system crystal layer 41 where the n-type dopant concentration is high is formed by ion implantation or the like.

The N addition region 401 is formed by ion implantation or the like at a position that blocks a space between: formed at 2 n⁺Channels between regions 402; and a second Ga₂O₃A system crystal layer 41 and a first Ga₂O₃Is the interface of the crystal layer 40. That is, the N addition region 401 is formed as the second Ga₂O₃A part of the system crystal layer 41, second Ga₂O₃Channel region in the system crystal layer 41 and the second Ga₂O₃Between the bottom surfaces of the series crystal layers 41. Therefore, the N-doped region 401 can be suppressed to be in the second Ga₂O₃A system crystal layer 41 and a first Ga₂O₃A leakage current flowing through the interface of the system crystal layer 40. The N concentration of the N addition region 401 is higher than that of the second Ga₂O₃A system crystal layer 41 (n)⁺Regions other than region 402).

Fig. 12 is a vertical cross-sectional view of MESFET4b of the fourth embodiment. In MESFET4b, the second Ga is distributed over the second Ga₂O₃Unlike MESFET4a, the crystalline layer has an N-added region.

Second Ga of MESFET4b₂O₃The system crystal layer 45 is in the first Ga₂O₃The layer formed by epitaxial crystal growth on the system crystal layer 40 includes Ga containing donor which is not intentionally added₂O₃Is a single crystal. The concentration of the donor to be added unintentionally is, for example, 1X 10¹⁸cm^-3The following. Second Ga₂O₃The thickness of the system crystal layer 45 is, for example, 0.02 to 100 μm.

In addition, in the second Ga₂O₃In the system crystal layer 45, N is intentionally added to compensate for the donor which is unintentionally added. In order to reduce the electron concentration, the second Ga is preferred₂O₃The N concentration of the system crystal layer 45 is equal to or less than the donor concentration which is not intentionally added. N is a radical of a second Ga₂O₃The crystal growth of the system crystal layer 45 is added in parallel, and the entire second Ga is added₂O₃The system crystal layer 45 becomes an N-added region. Further, N may be added to the second Ga by ion implantation₂O₃A crystal layer 45. In addition, when a group IV element such as Si or Sn is intentionally added together with N, the N concentration may be higher than the donor concentration which is not intentionally added.

Gate electrode 44 and second Ga₂O₃Schottky contact is made on the upper surface of the system crystal layer 45, and the second Ga is₂O₃A depletion layer is formed below the gate electrode 44 in the system crystal layer 45. The MESFET4b functions as a depletion transistor or an enhancement transistor according to the thickness of the depletion region.

(effects of the embodiment)

According to the first to fourth embodiments, Ga which has not been conventionally used can be used₂O₃Ga proceeds by N known as an acceptor used in the crystal₂O₃High resistance of the crystal or formation of a p-type region. Further, Ga having N added thereto can be provided₂O₃A semiconductor element of a crystal layer.