Semiconductor radio frequency device and method of manufacturing the same

Abstract

This application provides a semiconductor radio frequency (RF) device and its fabrication method. The semiconductor RF device includes, from bottom to top, a substrate and an n-type source doped layer; a ridge channel structure located in the middle, a first heterostructure layer disposed on one side of the ridge channel structure, and a second heterostructure layer disposed on the other side of the ridge channel structure; a drain electrode disposed on the ridge channel structure; a gate dielectric and a gate electrode disposed on the first and second heterostructure layers; a back hole structure disposed on the side of the substrate away from the n-type source doped layer, exposing the n-type source doped layer; a source electrode disposed in the back hole structure of the substrate; and a two-dimensional electron gas on the sidewall of the ridge channel structure of the first heterostructure layer. The above device is a vertical structure design, which can achieve higher device density compared to a horizontal structure. The gate length and channel size can be controlled by the film thickness, which reduces the precision requirements of the photolithography equipment and makes manufacturing easier.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a semiconductor radio frequency device and its fabrication method. Background Technology

[0002] Traditional GaN HEMT RF devices have a horizontal structure, achieving power amplification by controlling the two-dimensional electron gas at the Al(Ga)N / GaN heterojunction interface through the gate. A T-shaped gate electrode is designed to reduce gate resistance and increase the device's operating frequency. Higher operating frequencies require narrower gate feet in the T-shaped gate structure, reducing gate mechanical stability and demanding higher precision in fabrication equipment, thus increasing manufacturing difficulty. Furthermore, horizontally structured devices, due to the horizontal current transmission direction, also occupy a relatively large area. Summary of the Invention

[0003] The purpose of this application is to provide a semiconductor radio frequency device and a method for fabricating the same, so as to alleviate the above-mentioned technical problems.

[0004] In a first aspect, embodiments of this application provide a semiconductor radio frequency device, comprising: a substrate and an n-type source doped layer disposed sequentially from bottom to top; a ridge channel structure located in the middle, a first heterostructure layer disposed on one side of the ridge channel structure, and a second heterostructure layer disposed on the other side of the ridge channel structure; a drain electrode disposed on the ridge channel structure; a gate dielectric and a gate electrode disposed on both the first heterostructure layer and the second heterostructure layer; the side of the substrate away from the n-type source doped layer has a back hole structure, exposing the n-type source doped layer; a source electrode is disposed in the back hole structure of the substrate; and a two-dimensional electron gas is present on the sidewall of the ridge channel structure of the first heterostructure layer.

[0005] In a preferred embodiment of this application, the ridge channel structure includes: an unintentionally doped layer and an n-type drain doped layer disposed on the n-type source doped layer.

[0006] In a preferred embodiment of this application, the plane containing the sidewalls of the ridge channel structure is parallel to the (0001) plane of the substrate.

[0007] In a preferred embodiment of this application, the gate electrode forms a Schottky contact with the first heterostructure layer and the second heterostructure layer at the sidewall of the ridge channel structure.

[0008] In a preferred embodiment of this application, the Schottky contact is located at the end away from the drain electrode and close to the n-type source doped layer.

[0009] In a preferred embodiment of this application, the first heterostructure layer and the second heterostructure layer have the same structure, which is composed of one of AlGaN, InAlN, AlN or InAlGaN and GaN.

[0010] In a preferred embodiment of this application, the substrate is a group III nitride semiconductor having a non-polar surface.

[0011] In a preferred embodiment of this application, the substrate has high resistance.

[0012] In a preferred embodiment of this application, the gate dielectric covers a portion of the sidewalls of the first heterostructure layer and the second heterostructure layer.

[0013] Secondly, embodiments of this application also provide a method for fabricating a semiconductor radio frequency device, the method comprising: providing a substrate; sequentially growing an n-type source doped layer, an unintentionally doped layer, and an n-type drain doped layer on the substrate; etching the n-type drain doped layer and the unintentionally doped layer to form a ridge channel structure; forming a heterostructure layer on the ridge channel structure covering the sidewalls of the ridge channel structure, the n-type drain doped layer in the ridge channel structure, and the n-type source doped layer, wherein a two-dimensional electron gas is formed on one sidewall of the ridge channel structure by the heterostructure layer; and depositing a two-dimensional electron gas on the heterostructure layer. An insulating dielectric layer is deposited; a portion of the insulating dielectric layer on the sidewall of the heterostructure layer and the heterostructure layer on the n-type drain doped layer in the ridge channel structure are etched to form a gate dielectric layer; metal is deposited on the gate dielectric layer to form a gate electrode, and the gate electrode forms a Schottky contact with the first and second heterostructure layers on the sidewall of the ridge channel structure; metal is deposited on the n-type drain doped layer in the ridge channel structure to form a drain electrode; a back hole structure is etched on the side of the substrate away from the n-type source doped layer to expose the n-type source doped layer; metal is deposited in the back hole structure to form a source electrode.

[0014] The semiconductor radio frequency device and its fabrication method provided in this application include: a substrate and an n-type source doped layer arranged sequentially from bottom to top; a ridge channel structure located in the middle, a first heterostructure layer disposed on one side of the ridge channel structure, and a second heterostructure layer disposed on the other side of the ridge channel structure; a drain electrode disposed on the ridge channel structure; a gate dielectric and a gate electrode disposed on both the first and second heterostructure layers; a back hole structure on the side of the substrate away from the n-type source doped layer, exposing the n-type source doped layer; a source electrode disposed in the back hole structure of the substrate; and a two-dimensional electron gas on the sidewall of the ridge channel structure of the first heterostructure layer. The semiconductor radio frequency device provided in this embodiment is a vertical structure design, which can achieve higher device density compared to a horizontal structure. The gate length and channel size can be controlled by the film thickness, which reduces the precision requirements of the photolithography equipment and makes manufacturing easier. In this device, current is transported through a two-dimensional electron gas formed on the sidewalls of the ridged channel structure, resulting in a low channel resistance. Both the source and drain electrodes are fabricated on pre-grown n-type... + - GaN doped layers have low contact resistance; short gate length devices can be easily fabricated; non-polar GaN can be easily grown on large-size silicon (110) or (112) substrates, which has a cost advantage. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a semiconductor radio frequency device in the prior art;

[0017] Figure 2 This is a schematic diagram of the structure of a semiconductor radio frequency device provided in an embodiment of this application;

[0018] Figure 3 This is a schematic diagram of another semiconductor radio frequency device provided in an embodiment of this application;

[0019] Figure 4 The transmission and transconductance characteristics of a semiconductor radio frequency device are provided in the embodiments of this application;

[0020] Figure 5 An output characteristic curve of a semiconductor radio frequency device provided in an embodiment of this application;

[0021] Figure 6A flowchart illustrating a method for fabricating a semiconductor radio frequency device provided in this application embodiment;

[0022] Figure 7 This is a schematic diagram illustrating the fabrication process of a semiconductor radio frequency device provided in an embodiment of this application. Detailed Implementation

[0023] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] See Figure 1 As shown, traditional GaN HEMT RF devices have a horizontal structure, achieving power amplification by controlling the two-dimensional electron gas at the Al(Ga)N / GaN heterojunction interface through the gate. The fabrication of horizontal structure devices requires precise control over doping and device dimensions. For example, in... Figure 1 In the structure shown, to increase the device operating frequency, the gate is fabricated as a T-shaped structure that is narrow at the bottom (gate foot) and wide at the top (gate cap). The gate foot length is generally less than 100 nm. When the frequency is higher (e.g., exceeding 200 GHz), the gate foot length needs to be very short (e.g., 30 nm), thus requiring high precision in the processing equipment and making manufacturing difficult. On the other hand, to reduce the source-drain channel resistance, the source-drain spacing often needs to be miniaturized to below 1 μm. To reduce the contact resistance between the source and drain electrodes, a heavily doped n-type layer is usually grown again in the source and drain regions. + -GaN (doping concentration >10) 20 / cm 3 ).

[0025] Horizontal structures require precise control over doping and device dimensions, placing high demands on the precision of processing equipment and making them difficult to manufacture. Their main drawbacks include the following:

[0026] 1) The manufacturing of T-shaped gate structures requires high-precision photolithography equipment and photoresist. Moreover, when the gate foot is very short, it will affect the overall mechanical stability of the T-shaped gate, making manufacturing difficult.

[0027] 2) Current transmission is in the horizontal direction, and the device area is relatively large.

[0028] Based on this, this application provides a semiconductor radio frequency device and its fabrication method. To facilitate understanding of this embodiment, a semiconductor radio frequency device disclosed in this application will be described in detail first.

[0029] Figure 2A semiconductor radio frequency device provided in this application includes: a substrate 201 and an n-type source doped layer 202 disposed sequentially from bottom to top; a ridge channel structure 203 located in the middle, a first heterostructure layer 204 disposed on one side of the ridge channel structure 203, and a second heterostructure layer 205 disposed on the other side of the ridge channel structure 203 are disposed on the n-type source doped layer 202; a drain electrode 206 is disposed on the ridge channel structure 203; a gate dielectric 207 and a gate electrode 208 are disposed on both the first heterostructure layer 204 and the second heterostructure layer 205; the side of the substrate 201 away from the n-type source doped layer 202 has a back hole structure, exposing the n-type source doped layer 202; a source electrode 209 is disposed in the back hole structure of the substrate 201; and the first heterostructure layer 204 has a two-dimensional electron gas on the sidewall of the ridge channel structure 203.

[0030] The semiconductor radio frequency device provided in this embodiment features a vertical structure design, which allows for higher device density compared to a horizontal structure. The gate length and channel size can be controlled by the film thickness, reducing the precision requirements of the photolithography equipment and simplifying manufacturing. In this device, current is transported through a two-dimensional electron gas formed on the sidewalls of the ridge-shaped channel structure, resulting in a low channel resistance. Both the source and drain electrodes are fabricated on a pre-grown n-layer... + - GaN doped layers have low contact resistance; short gate length devices can be easily fabricated; non-polar GaN can be easily grown on large-size silicon (110) or (112) substrates, which has a cost advantage.

[0031] In a preferred embodiment of this application, the ridge channel structure includes: an unintentionally doped layer and an n-type drain doped layer disposed on the n-type source doped layer.

[0032] In a preferred embodiment of this application, the plane containing the sidewalls of the ridge channel structure is parallel to the (0001) plane of the substrate.

[0033] In a preferred embodiment of this application, the gate electrode forms a Schottky contact with the first heterostructure layer and the second heterostructure layer at the sidewall of the ridge channel structure.

[0034] In a preferred embodiment of this application, the Schottky contact is located at the end away from the drain electrode and close to the n-type source doped layer.

[0035] In a preferred embodiment of this application, the first heterostructure layer and the second heterostructure layer have the same structure, which is composed of one of AlGaN, InAlN, AlN or InAlGaN and GaN.

[0036] In a preferred embodiment of this application, the substrate is a group III nitride semiconductor having a non-polar surface.

[0037] In a preferred embodiment of this application, the substrate has high resistance.

[0038] In a preferred embodiment of this application, the gate dielectric covers a portion of the sidewalls of the first heterostructure layer and the second heterostructure layer.

[0039] The following is a specific example of a gallium nitride semiconductor radio frequency device, its structural schematic diagram is shown below. Figure 3 As shown, in this structure, the first heterostructure layer and the second heterostructure layer are both AlGaN / GaN layers; the substrate is a non-polar GaN layer; the n-type source doped layer is a high-resistivity GaN layer; and both the n-type source doped layer and the n-type drain doped layer are n-type... + -GaN layer.

[0040] Gallium nitride semiconductor radio frequency devices have the following characteristics:

[0041] 1) From bottom to top, the components are substrate, n + -GaN source doped layer, unintentionally doped GaN ridge channel structure (such as...) Figure 3 (The layer corresponding to a thickness of 1µm) and n above the ridge channel structure + -GaN drain doped layer (e.g.) Figure 3 (The layer shown in n+); the sidewalls of the ridge-shaped channel structure are parallel to the c-plane of GaN;

[0042] 2) Ridge-shaped channel structure sidewalls and n + - An AlGaN barrier layer is deposited on the surface of the GaN source doped layer. The AlGaN / GaN heterojunction interface on the sidewalls along the +c direction has a two-dimensional electron gas, which serves as a channel for current transport.

[0043] 3) SiN deposited on AlGaN surface x The dielectric layer has one end in contact with the AlGaN barrier layer sidewalls on both sides of the ridge channel structure.

[0044] 4) In the uppermost layer n of the ridge-shaped channel structure + A drain electrode is formed on the GaN drain doped layer; in SiN x A gate electrode is disposed on the surface of the dielectric layer, and one end of the gate electrode layer is in contact with the sidewall of the AlGaN barrier layer to form a Schottky contact.

[0045] 5) Etch a back hole structure on the back side of the substrate to expose the source doped layer; deposit metal in the back hole structure to form the source electrode.

[0046] Figure 4 for Figure 3The transmission and transconductance characteristics of the specific GaN RF device structure are shown. The device threshold voltage is approximately -4V, and the device exhibits good linearity within the gate voltage range of -3V to 2V.

[0047] Figure 5 for Figure 3 The output characteristic curves of a specific GaN RF device structure are shown.

[0048] Based on the above structural embodiments, this application also provides a method for fabricating a semiconductor radio frequency device, see [link to relevant documentation]. Figure 6 As shown, the method specifically includes the following steps:

[0049] Step S402, provide a substrate;

[0050] Step S404: An n-type source doped layer, an unintentionally doped layer, and an n-type drain doped layer are sequentially grown on the substrate.

[0051] Step S406: Etch the n-type drain doped layer and the unintentionally doped layer to form a ridge channel structure; Step S408: Form a heterostructure layer on the ridge channel structure covering the sidewall of the ridge channel structure, the n-type drain doped layer in the ridge channel structure, and the n-type source doped layer, and form a two-dimensional electron gas on one sidewall of the ridge channel structure.

[0052] Step S410: Deposit an insulating dielectric layer on the heterostructure layer; etch a portion of the insulating dielectric layer on the sidewall of the heterostructure layer and the heterostructure layer on the n-type drain doped layer in the ridge channel structure to form a gate dielectric layer; deposit metal on the gate dielectric layer to form a gate electrode, and form a Schottky contact between the gate electrode and the first heterostructure layer and the second heterostructure layer on the sidewall of the ridge channel structure.

[0053] Step S412: Deposit metal on the n-type drain doped layer in the ridge channel structure to form a drain electrode;

[0054] Step S414: Etch a back hole structure on the side of the substrate away from the n-type source doped layer to expose the n-type source doped layer; deposit metal in the back hole structure to form a source electrode.

[0055] See Figure 7 As shown, the specific implementation process of the semiconductor radio frequency device is as follows:

[0056] 1) Provide a nonpolar gallium nitride template as a substrate;

[0057] 2) Growing an n-type source doped layer (n) on a gallium nitride template + -GaN);

[0058] 3) An unintentionally doped gallium nitride (u-GaN) layer is grown on the n-type source doped layer; an n-type drain doped layer is grown on the unintentionally doped gallium nitride layer. + -GaN);

[0059] 4) Etching n + - The GaN drain doped layer and the u-GaN layer form a ridge channel structure, and the sidewalls of the ridge channel structure are parallel to the c-plane of GaN.

[0060] 5) Regenerated AlGaN forms vertical channels;

[0061] 6) Deposition medium layer;

[0062] 7) Etch away the unwanted dielectric layer and top AlGaN layer;

[0063] 8) Fabricate source, gate, and drain electrodes.

[0064] The semiconductor radio frequency device fabrication method provided in this embodiment realizes a vertical structure design method, which can achieve higher device density compared to horizontal structures. The gate length and channel size can be controlled by the film thickness, and the precision requirements of the photolithography equipment are low, making the manufacturing process easier. In this device, the current is transported through a two-dimensional electron gas formed on the sidewalls of the ridge-shaped channel structure, and the device has a small channel resistance. Both the source electrode and the drain electrode are fabricated on a pre-grown n-layer. + - GaN doped layers have low contact resistance; short gate length devices can be easily fabricated; non-polar GaN can be easily grown on large-size silicon (110) or (112) substrates, which has a cost advantage.

[0065] The method provided in this application embodiment has the same implementation principle and technical effect as the aforementioned structural embodiment. For the sake of brevity, any part of the method not mentioned in the embodiment section can be referred to the corresponding content in the aforementioned structural embodiment.

[0066] Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0067] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0068] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A semiconductor radio frequency device, characterized in that, The semiconductor radio frequency device includes, from bottom to top, a substrate and an n-type source doped layer; on the n-type source doped layer, a ridge channel structure located in the middle, a first heterostructure layer disposed on one side wall of the ridge channel structure and on the n-type source doped layer, and a second heterostructure layer disposed on the other side wall of the ridge channel structure and on the n-type source doped layer; a drain electrode is disposed on the ridge channel structure; a gate dielectric and a gate electrode are disposed on both the first heterostructure layer and the second heterostructure layer; a back hole structure is disposed on the side of the substrate away from the n-type source doped layer, exposing the n-type source doped layer; a source electrode is disposed in the back hole structure of the substrate; the first heterostructure layer has a two-dimensional electron gas on the side wall of the ridge channel structure; The gate electrode forms a first Schottky contact with the first heterostructure layer at the sidewall of the ridge channel structure; the gate electrode forms a second Schottky contact with the second heterostructure layer at the sidewall of the ridge channel structure; both the first Schottky contact and the second Schottky contact are located at the end away from the drain electrode and close to the n-type source doped layer.

2. The semiconductor radio frequency device according to claim 1, characterized in that, The ridge channel structure includes: an unintentionally doped layer and an n-type drain doped layer disposed on the n-type source doped layer.

3. The semiconductor radio frequency device according to claim 1, characterized in that, The plane containing the sidewalls of the ridge channel structure is parallel to the (0001) plane of the substrate.

4. The semiconductor radio frequency device according to claim 1, characterized in that, The first heterostructure layer and the second heterostructure layer have the same structure, including one of AlGaN, InAlN, AlN or InAlGaN.

5. The semiconductor radio frequency device according to claim 1, characterized in that, The substrate is a group III nitride semiconductor with a non-polar surface.

6. The semiconductor radio frequency device according to claim 5, characterized in that, The substrate has high resistance.

7. The semiconductor radio frequency device according to claim 1, characterized in that, The gate dielectric covers a portion of the sidewalls of the first heterostructure layer and the second heterostructure layer near the n-type source doped layer.

8. A method for fabricating a semiconductor radio frequency device, characterized in that, The method includes: Provide substrate; An n-type source doped layer, an unintentionally doped layer, and an n-type drain doped layer are sequentially grown on the substrate. The n-type drain doped layer and the unintentionally doped layer are etched to form a ridge channel structure; A heterostructure layer is formed on the ridge channel structure, covering the sidewalls of the ridge channel structure, the n-type drain doped layer in the ridge channel structure, and the n-type source doped layer. The heterostructure layer forms a two-dimensional electron gas on one sidewall of the ridge channel structure. The heterostructure layer includes: a first heterostructure layer disposed on one sidewall of the ridge channel structure and the n-type source doped layer, and a second heterostructure layer disposed on the other sidewall of the ridge channel structure and the n-type source doped layer. An insulating dielectric layer is deposited on the heterostructure layer; Etching a portion of the insulating dielectric layer on the sidewall of the heterostructure layer and the heterostructure layer on the n-type drain doped layer in the ridge channel structure to form a gate dielectric layer; A gate electrode is formed by depositing metal on the gate dielectric layer, and a drain electrode is formed by depositing metal on the n-type drain doped layer in the ridge channel structure. The gate electrode forms a first Schottky contact with a first heterostructure layer at the sidewall of the ridge channel structure. The gate electrode forms a second Schottky contact with a second heterostructure layer at the sidewall of the ridge channel structure. Both the first and second Schottky contacts are located at the end away from the drain electrode and closer to the n-type source doped layer. A back hole structure is etched on the side of the substrate away from the n-type source doped layer to expose the n-type source doped layer; Metal is deposited in the back hole structure to form a source electrode.

Images