阅读说明：本技术 高电子迁移率晶体管及高压半导体装置 (High electron mobility transistor and high voltage semiconductor device ) 是由 黄嘉庆 陈志谚 吴俊仪 萧智仁 于 2020-06-30 设计创作，主要内容包括：一种高电子迁移率晶体管,包括基底、三五族沟道层、三五族阻挡层、三五族盖层、源极电极、第一漏极电极、第二漏极电极、以及连接部。其中,三五族沟道层、三五族阻挡层、及三五族盖层依序设置于基底上。源极电极设置于三五族盖层的一侧,第一漏极电极及第二漏极电极设置于三五族盖层的另一侧。第一漏极电极的底面分离于第二漏极电极的底面,且第一漏极电极的组成不同于第二漏极电极的组成。连接部电连接至第一漏极电极以及第二漏极电极。(A high electron mobility transistor includes a substrate, a III-V channel layer, a III-V barrier layer, a III-V cap layer, a source electrode, a first drain electrode, a second drain electrode, and a connection portion. Wherein, the III-V channel layer, the III-V barrier layer and the III-V cover layer are sequentially arranged on the substrate. The source electrode is arranged on one side of the III-V group cover layer, and the first drain electrode and the second drain electrode are arranged on the other side of the III-V group cover layer. The bottom surface of the first drain electrode is separated from the bottom surface of the second drain electrode, and the composition of the first drain electrode is different from the composition of the second drain electrode. The connection portion is electrically connected to the first drain electrode and the second drain electrode.)

1. A high electron mobility transistor, comprising:

a III-V channel layer, a III-V barrier layer and a III-V cover layer, which are sequentially arranged on a substrate;

the source electrode is arranged on one side of the III-V group cover layer;

a first drain electrode and a second drain electrode disposed on the other side of the III-V group cap layer, wherein the bottom surface of the first drain electrode is separated from the bottom surface of the second drain electrode, and the composition of the first drain electrode is different from the composition of the second drain electrode; and

a connection part electrically connected to the first drain electrode and the second drain electrode.

2. The hemt of claim 1, wherein a bottom surface of said first drain electrode is higher than a bottom surface of said second drain electrode.

3. The hemt of claim 1, wherein a bottom surface of said first drain electrode and a bottom surface of said second drain electrode each contact different layers.

4. The hemt of claim 1, wherein said first drain electrode comprises a schottky contact with said group iii-v barrier layer and said second drain electrode comprises an ohmic contact with said group iii-v channel layer.

5. The hemt of claim 1, wherein said connecting means comprises a conductive plug or a conductive link, wherein said connecting means has the same composition as said first drain electrode or said second drain electrode.

6. The high electron mobility transistor according to claim 1, further comprising:

an interlayer dielectric layer disposed on the III-V barrier layer and including a first drain contact hole and a second drain contact hole, wherein the first drain contact hole is separated from the second drain contact hole;

the first drain electrode is arranged in the first drain contact hole; and

the second drain electrode is arranged in the second drain contact hole.

7. The hemt of claim 6, wherein said interlayer dielectric layer further comprises a gate contact hole disposed on a top surface of said iii-v cap layer.

8. The hemt of claim 7, further comprising a gate electrode disposed in said gate contact hole, wherein said gate electrode has a composition identical to that of said first drain electrode.

9. The hemt of claim 1, wherein said first drain electrode comprises TiN, W, Pt, Ni or Ni/Au.

10. The hemt of claim 1, wherein said second drain electrode comprises a material selected from the group consisting of Ti/Al, Ti/Al/Ti/TiN, Ti/Al/Ti/Au, Ti/Al/Ni/Au, and Ti/Al/Mo/Au.

11. A high voltage semiconductor device, comprising:

a semiconductor layer disposed on a substrate;

a semiconductor cover layer arranged on the semiconductor layer;

the source electrode is arranged on one side of the semiconductor cover layer;

at least two drain electrodes disposed on the other side of the semiconductor cap layer, wherein each of the at least two drain electrodes comprises a schottky contact metal and an ohmic contact metal; and

and the interlayer dielectric layer is arranged between the Schottky contact metal and the ohmic contact metal.

12. The high voltage semiconductor device according to claim 11, wherein the schottky contact metal is electrically connected to the ohmic contact metal.

13. The high voltage semiconductor device of claim 11, further comprising a gate electrode electrically connected to said semiconductor cap layer, wherein said gate electrode has a composition identical to a composition of said schottky contact metal.

14. The high voltage semiconductor device according to claim 11, further comprising a conductive plug disposed on the schottky contact metal, wherein the conductive plug is electrically connected to the schottky contact metal and the ohmic contact metal.

15. The high voltage semiconductor device according to claim 14, wherein a composition of the conductive plug is the same as a composition of the ohmic contact metal or the schottky contact metal.

16. The high voltage semiconductor device of claim 14, further comprising another interlayer dielectric layer disposed over the interlayer dielectric layer, wherein the another interlayer dielectric layer is disposed between the conductive plug and the ohmic contact metal.

17. The high voltage semiconductor device of claim 16, further comprising a conductive line disposed on a surface of the another interlayer dielectric layer, wherein the conductive line is electrically connected to the conductive plug and the ohmic contact metal.

18. The high voltage semiconductor device according to claim 11, wherein the semiconductor layer comprises a iii-v channel layer and a iii-v barrier layer sequentially disposed on the substrate, the schottky contact metal penetrates the interlayer dielectric layer, and the ohmic contact metal penetrates the interlayer dielectric layer and the iii-v barrier layer.

19. The high voltage semiconductor device of claim 11, wherein said schottky contact metal comprises a schottky contact with said semiconductor layer and said ohmic contact metal comprises an ohmic contact with said semiconductor layer.

20. The high voltage semiconductor device of claim 11, wherein said at least two drain electrodes further comprise another schottky contact metal, said another schottky contact metal being separate from said schottky contact metal and from said ohmic contact metal.

Technical Field

The present invention relates to the field of semiconductor devices, and more particularly, to a high electron mobility transistor and a high voltage semiconductor device.

Background

In semiconductor technology, III-V semiconductor compounds are useful in forming a variety of integrated circuit devices, such as: a high power field effect transistor, a high frequency transistor, or a High Electron Mobility Transistor (HEMT). A HEMT is a transistor having a two-dimensional electron gas (2-DEG), wherein the 2-DEG is adjacent to a junction (i.e., a heterojunction) between two materials having different energy gaps. Because HEMTs do not use doped regions as the carrier channel of transistors, but 2-DEG as the carrier channel of transistors, HEMTs have a number of attractive properties compared to known metal-oxide-semiconductor field-effect transistors (MOSFETs), such as: high electron mobility and the ability to transmit signals at high frequencies.

With the known HEMT, ohmic contact (ohmic contact) is formed between the drain electrode and the underlying semiconductor layer to reduce contact resistance between the drain electrode and the semiconductor layer. However, in the process of forming ohmic contact, the metal in the drain electrode usually reacts with the underlying semiconductor layer to form spike defects (spiking defects), so that the local electric field adjacent to the spike defects is larger, which causes unnecessary leakage current, thereby increasing the off-state current (I) of the semiconductor device_OFF) Reducing breakdown voltage and reliability.

Disclosure of Invention

Accordingly, there is a need for an improved hemt to improve the defects of the conventional hemts.

According to an embodiment of the present invention, there is provided a high electron mobility transistor including a substrate, a group iii-v channel layer, a group iii-v barrier layer, a group iii-v cap layer, a source electrode, a first drain electrode, a second drain electrode, and a connection portion. Wherein, the III-V channel layer, the III-V barrier layer and the III-V cover layer are sequentially arranged on the substrate. The source electrode is arranged on one side of the III-V group cover layer, and the first drain electrode and the second drain electrode are arranged on the other side of the III-V group cover layer. The bottom surface of the first drain electrode is separated from the bottom surface of the second drain electrode, and the composition of the first drain electrode is different from the composition of the second drain electrode. The connection portion is electrically connected to the first drain electrode and the second drain electrode.

According to another embodiment of the present invention, a high voltage semiconductor device is provided, which includes a semiconductor layer, a semiconductor cap layer, a source electrode, at least two drain electrodes, and an interlayer dielectric layer. The grid structure is arranged on the semiconductor layer. The source electrode is arranged on one side of the semiconductor cover layer, and the drain electrode is arranged on the other side of the semiconductor cover layer, wherein the drain electrode comprises Schottky contact metal and ohmic contact metal. The interlayer dielectric layer is arranged between the Schottky contact metal and the ohmic contact metal.

According to the embodiments of the present invention, by providing the first drain electrode and the second drain electrode laterally separated from each other and making the first drain electrode form a schottky contact with the underlying semiconductor layer and the second drain electrode forms an ohmic contact with the underlying semiconductor layer, it is possible not only to improve the distribution of the surface electric field of the high voltage semiconductor device but also to reduce the off-current (I) of the device_OFF) While preventing an excessive increase in the contact area between the bottom surface of the drain electrode and the semiconductor layer, thereby preventing the on-resistance (R) of the semiconductor device_ON) Is increased.

Drawings

For the following to be more readily understood, reference is made to the drawings and to the detailed description thereof, when read in conjunction with the appended drawings. The embodiments of the present invention are illustrated in detail by the embodiments herein and with reference to the corresponding drawings, and the functional principle of the embodiments of the present invention is explained. Furthermore, for purposes of clarity, the various features in the drawings may not be to scale and the dimensions of some of the features in some drawings may be exaggerated or minimized.

Fig. 1 is a cross-sectional view of a high voltage semiconductor device having a plurality of drain electrodes according to an embodiment of the invention.

Fig. 2 is a schematic top view of a high voltage semiconductor device according to an embodiment of the invention, taken along line a-a' of fig. 1.

Fig. 3 is a cross-sectional view of a high voltage semiconductor device having a plurality of drain electrodes according to an embodiment of the invention.

Fig. 4 is a cross-sectional view of a high voltage semiconductor device having a plurality of drain electrodes according to an embodiment of the invention.

FIG. 5 is a cross-sectional view of a high voltage semiconductor device having a III-V channel layer, a III-V barrier layer, a III-V cap layer, and an interlayer dielectric layer disposed on a substrate according to an embodiment of the invention.

Fig. 6 is a cross-sectional view of a high voltage semiconductor device having a gate electrode and a first drain electrode disposed in an interlayer dielectric layer according to an embodiment of the invention.

Fig. 7 is a cross-sectional view of a high voltage semiconductor device having a source contact hole and a second drain contact hole in an interlayer dielectric layer according to an embodiment of the invention.

Fig. 8 is a cross-sectional view of a high voltage semiconductor device having a source electrode and a second drain electrode disposed in an interlayer dielectric layer according to an embodiment of the invention.

Fig. 9 is a flowchart illustrating a method of fabricating a high voltage semiconductor device according to an embodiment of the invention.

The reference numerals are explained below:

10: a high electron mobility transistor; 10': a high electron mobility transistor;

10": a high electron mobility transistor; 100: a substrate; 102: a buffer layer; 104: a III-V channel layer;

106: a III-V barrier layer; 112: a III-V cap layer; 114: an etch stop layer; 116: a passivation layer;

120: a two-dimensional electron gas region; 122: a two-dimensional electron gas cutoff region; 124: a first interlayer dielectric layer;

126: a second interlayer dielectric layer; 128: an insulating structure; 130: a gate contact hole; 132: a source contact hole;

134: a first drain contact hole; 136: a second drain contact hole; 138: opening a hole; 140: a gate electrode;

142: a first drain electrode; 142': a first drain electrode; 143: a bottom surface; 143': a bottom surface;

144: a source electrode; 146: a field plate; 148: a second drain electrode; 150: conductive plug

150': a conductive plug; 152: a conductive connection; 154: a third interlayer dielectric layer; 160: a stack structure;

200: a method; 202: a step of; 204: a step of; 206: a step of; 208: a step of; 210: step (ii) of

L_GD: a distance; l is_DD: a distance; l'_DD: a distance; w: a bottom surface width; w': width of bottom surface

Detailed Description

The present invention provides many different embodiments, which can be used to implement different features of the present invention. Examples of specific components and arrangements are described herein for simplicity of illustration. These examples are provided for the purpose of illustration only and are not intended to be limiting in any way. For example, the following description of the first feature being formed on or over the second feature may refer to the first feature being in direct contact with the second feature, or there may be additional features between the first feature and the second feature, such that the first feature and the second feature are not in direct contact. Moreover, various embodiments of the present invention may use repeated reference characters and/or written notation. These repeated reference characters and notations are used to make the description more concise and unambiguous and are not used to indicate any relationship between the different embodiments and/or configurations.

In addition, for spatially related descriptive words mentioned in the present invention, for example: the use of "under", "lower", "above", "over", "lower", "top", "bottom" and similar terms in describing, for convenience of description, one element or feature in relation to another element(s) or feature in the drawings is intended. In addition to the orientations shown in the drawings, these spatially relative terms are also used to describe possible orientations of the semiconductor device during use and operation. With respect to the swinging direction of the semiconductor device (rotated 90 degrees or other orientations), the spatially relative descriptions used to describe the swinging direction should be interpreted in a similar manner.

Although the present invention has been described using terms such as first, second, third, etc. to describe various elements, components, regions, layers and/or sections, it should be understood that such elements, components, regions, layers and/or sections should not be limited by such terms. These terms are only used to distinguish one element, component, region, layer and/or block from another element, component, region, layer and/or block, and do not denote any order or importance, nor do they denote any order or importance, unless otherwise indicated. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the scope of embodiments of the present invention.

The term "about" or "substantially" as used herein generally means within 20%, preferably within 10%, and more preferably within 5%, or within 3%, or within 2%, or within 1%, or within 0.5% of a given value or range. It should be noted that the amounts provided in the specification are approximate amounts, that is, the meaning of "about" or "substantially" may still be implied without specific recitation of "about" or "substantially".

In the present invention, "group III-V semiconductor" refers to a compound semiconductor containing at least one group III element and at least one group V element. Among them, the group III element may be boron (B), aluminum (Al), gallium (Ga), or indium (In), and the group V element may be nitrogen (N), phosphorus (P), arsenic (As), or antimony (Sb). Further, "iii-v semiconductors" may include: gallium nitride (GaN), indium phosphide (InP), aluminum arsenide (AlAs), gallium arsenide (GaAs), aluminum gallium nitride (AlGaN), indium aluminum gallium nitride (InAlGaN), indium gallium nitride (InGaN), aluminum nitride (AlN), indium gallium phosphide (GaInP), aluminum gallium arsenide (AlGaAs), aluminum indium arsenide (InAlAs), indium gallium arsenide (InGaAs), the like, or combinations thereof, but is not limited thereto. Furthermore, if desired, the III-V semiconductor may also include dopants therein, such as N-type or P-type III-V semiconductors having a particular conductivity type.

Although the invention is described below in terms of specific embodiments, the inventive principles of this invention are also applicable to other embodiments. Moreover, certain details may be omitted so as not to obscure the spirit of the invention, the omitted details being within the scope of one of ordinary skill in the art.

The present invention relates to a high voltage semiconductor device or a High Electron Mobility Transistor (HEMT), such as a power switching transistor that can be applied as a voltage converter. The III-V HEMT has a wider energy band gap and thus a low on-state resistance (R) compared to silicon power transistors_ON) And low switching losses.

Fig. 1 is a schematic cross-sectional view of a high voltage semiconductor device according to an embodiment of the invention. As shown in fig. 1, a high voltage semiconductor device, such as an enhancement mode hemt 10, is disposed on a substrate 100, and a buffer layer 102, a III-V channel layer (or III-V channel layer) 104, a III-V barrier layer (or III-V barrier layer) 106, a passivation layer 116, and at least one interlayer dielectric layer (e.g., a first interlayer dielectric layer 124, a second interlayer dielectric layer 126, and a third interlayer dielectric layer 154) may be sequentially disposed on the substrate 100. An insulating structure 128 may be disposed on both sides of the III-V channel layer 104 and the III-V barrier layer 106.

The stack structure 160 includes a III-V cap layer 112 and an etch stop layer 114 stacked in sequence, disposed on the surface of the III-V barrier layer 106, and covered by a first interlayer dielectric layer 124. The gate electrode 140 may be disposed within the gate contact hole 130 of the first interlayer dielectric layer 124. Since the stack structure 160 may be exposed from the gate contact hole 130, the gate electrode 140 may be electrically connected to the underlying stack structure 160.

The source electrode 144 may be disposed on one side of the stack structure 160 and disposed in the source contact hole 132 in the first interlayer dielectric layer 124 in a homeotropic manner, and forms an ohmic contact with an underlying semiconductor layer, such as the III-V channel layer 104. A field plate 146 may be disposed along a top surface of the second interlayer dielectric layer 126, crossing over the stack structure 160. The field plate 146 can be electrically connected to the source electrode 144 for modulating an electric field distribution within the semiconductor layer (e.g., the III-V channel layer 104 and/or the III-V barrier layer 106). According to an embodiment of the present invention, the field plate 146 and the source electrode 144 can be formed by the same deposition process, and thus have the same composition with each other, but are not limited thereto.

In one embodiment, the material of the gate electrode 140 and the source electrode 144 may comprise a conductive material, such as a metal, an alloy, a metal nitride, or a semiconductor material. In some embodiments, the metal may comprise gold (Au), nickel (Ni), platinum (Pt), palladium (Pd), iridium (Ir), titanium (Ti), chromium (Cr), tungsten (W), aluminum (Al), copper (Cu), molybdenum (Mo), other suitable conductive materials, or combinations of the foregoing.

At least two drain electrodes, such as the first drain electrode 142 and the second drain electrode 148, may be disposed opposite to the source electrode 144 and on the other side of the stack structure 160. The first drain electrode 142 may be disposed in the first drain contact hole 134 of the first interlayer dielectric layer 124, and the composition of the first drain electrode 142 may be the same as that of the gate electrode 140, such as a composition including schottky contact metal. In an embodiment, the bottom surface 143 of the first drain electrode 142 may be disposed on the passivation layer 116. In a preferred embodiment, the bottom surface 143 of the first drain electrode 142 may be selectively electrically connected to an underlying semiconductor layer, such as the group III-V barrier layer 106, to form a schottky contact. According to an embodiment of the present invention, the first drain electrode 142 may penetrate the passivation layer 116 and be electrically connected to the underlying semiconductor layer, but the present invention is not limited thereto. In the present invention, the Schottky contact metal refers to a metal, an alloy or a stacked layer thereof that can make Schottky contact (Schottky contact) with a semiconductor layer in contact, and is, for example, TiN, W, Pt, Ni or Ni/Au, but is not limited thereto. Also, the second drain electrode 148 may be disposed within the second drain contact hole 136 of the first interlayer dielectric layer 124, with the second drain contact hole 136 laterally separated from the first drain contact hole 134. The composition of the second drain electrode 148 may be different from the composition of the gate electrode 140 and the first drain electrode 142 while having the same composition as the first source electrode 144. For example, the second drain electrode 148 may be composed of an ohmic contact metal. The bottom surface of the second drain electrode 148 may be electrically connected to an underlying semiconductor layer, such as the III-V channel layer 104, to form an ohmic contact. In the present invention, the ohmic contact metal refers to a metal, an alloy or a stacked layer thereof that can make ohmic contact (ohmic contact) with a semiconductor layer in contact, and is, for example, but not limited to, Ti/Al/Ti/TiN, Ti/Al/Ti/Au, Ti/Al/Ni/Au or Ti/Al/Mo/Au.

Further, the first drain electrode 142 may be electrically connected to the second drain electrode 148, for example, through a connection portion disposed above the first drain electrode 142 such that the first drain electrode 142 is electrically connected to the second drain electrode 148. For example, the connection portion may include a conductive plug 150 and a conductive line 152, wherein the conductive plug 150 may be disposed in the opening 150 of the second interlayer dielectric layer 126, and the conductive line 152 may be disposed on the top surface of the second interlayer dielectric layer 126 in a forward direction. According to an embodiment of the present invention, the connection portion (e.g., the conductive plug 150 or the conductive wire 152) and the second drain electrode 148 may be formed by the same deposition process, and thus may have the same composition with each other, but is not limited thereto. According to other embodiments, the composition of the connection portion (e.g., the conductive plug 150 or the conductive wire 152) may be the same as the composition of the first drain electrode 142 and different from the composition of the second drain electrode 148. In addition, the composition of the connection portion may also be selected from other metals or alloys, different from the composition of the first and second drain electrodes 142 and 148.

According to an embodiment of the present invention, the bottom surface 143 of the first drain electrode 142 may be higher than the bottom surface of the second drain electrode 148, such that the bottom surface 143 of the first drain electrode 142 and the bottom surface of the second drain electrode 148 may each contact different semiconductor layers. In addition, a first interlayer dielectric layer 124 may be disposed between the first drain electrode 142 and the second drain electrode 148, and a second interlayer dielectric layer 126 may be disposed between the conductive plug 150 and the second drain electrode 148.

According to an embodiment of the present invention, since the first drain electrode 142 and the second drain electrode 148 are respectively located in the first drain contact hole 134 and the second drain contact hole 136 which are separately disposed, the bottom width W of the first drain electrode 142 and the distance L between the first drain electrode 142 and the second drain electrode 148_DDCan be independently controlled; in addition, the bottom width W of the first drain electrode 142 and the distance L between the stack structure 160 and the first drain electrode 142_GDOr may be independently controlled. In other words, when the width W of the bottom surface of the first drain electrode 142 is increased or decreased, the distance L is not necessarily increased or decreased_DDOr a distance L_GD. Since the increase of the bottom width W of the first drain electrode 142 generally causes the increase of the on-resistance, in order to reduce the electric field distribution of the high voltage semiconductor device and thus the off-current of the high voltage semiconductor device without increasing the on-resistance, according to an embodiment of the present invention, the distance L between the first drain electrode 142 and the stack structure 160 can be arbitrarily set without changing the bottom width W_GDTo optimize the electric field distribution (or potential distribution) within the III-V barrier layer 106 and the III-V channel layer 104 to reduce the off-current of the high voltage semiconductor device.

According to an embodiment of the present invention, the substrate 100 may be a bulk silicon substrate, a silicon carbide (SiC) substrate, or an aluminum oxide (Al) substrate₂O₃) A substrate (also referred to as a sapphire substrate), a ceramic base such as aluminum nitride (AlN), a Silicon On Insulator (SOI) substrate, or a Germanium On Insulator (GOI) substrate, but is not limited thereto. In another embodiment, the substrate 100 further comprises one or more layers of insulating material and/or other suitable materials (e.g., semiconductor layers) and a core layer. The layer of insulating material may be an oxide, nitride, oxynitride, or other suitable insulating material. The core layer may be silicon carbide (SiC), aluminum nitride (AlN), aluminum gallium nitride (AlGaN), zinc oxide (ZnO) or gallium oxide (Ga)₂O₃) Or other suitable ceramic material. In one embodiment, a single or multiple layers of insulating material and/or other materialsA suitable layer of material surrounds the core layer. According to an embodiment of the present invention, the III-V channel layer 104 may include one or more III-V semiconductor layers, and the composition of the III-V semiconductor layers may be GaN, AlGaN, InGaN, or InAlGaN, but is not limited thereto. The buffer layer 102 may be used to reduce the degree of stress or lattice mismatch that exists between the substrate 100 and the III-V channel layer 104. The III-V channel layer 104 may also be one or more doped III-V semiconductor layers, such as P-type III-V semiconductor layers. For the P-type III-V semiconductor layer, the dopant may be C, Fe, Mg or Zn, or not limited thereto. The III-V barrier layer 106 may include one or more III-V semiconductor layers and may have a composition different from the III-V semiconductor of the III-V channel layer 104. For example, the III-V barrier layer 106 may comprise AlN, Al_yGa_1-yN (0 < y < 1), or a combination thereof. According to an embodiment, the III-V channel layer 104 may be an undoped GaN layer, and the III-V barrier layer 106 may be an AlGaN layer that is N-type in nature. Due to the discontinuous energy gap between the III-V channel layer 104 and the III-V barrier layer 106, by stacking the III-V channel layer 104 and the III-V barrier layer 106 on top of each other, electrons are collected at the heterojunction between the III-V channel layer 104 and the III-V barrier layer 106 due to piezoelectric effect (piezo effect), thereby creating a thin layer with high electron mobility, i.e., a two-dimensional electron gas (2-DEG) region 120. In contrast, the region covered by the III-V cap layer 112 is considered to be the two-dimensional electron gas intercepting region 122 because no two-dimensional electron gas is formed. According to an embodiment of the present invention, since the first drain electrode 142 does not penetrate into the group III-V barrier layer 106, the two-dimensional electron gas region 120 may be formed under the first drain electrode 142. The III-V cap layer 112 may comprise one or more III-V semiconductor layers, and the composition of the III-V semiconductor layers may be GaN, AlGaN, InGaN, or InAlGaN, but is not limited thereto. In addition, the III-V cap layer 112 may also be one or more doped III-V semiconductor layers, such as P-type III-V semiconductor layers. For the P-type III-V semiconductor layer, the dopant may be C, Fe, Mg or Zn, but is not limited thereto. In accordance with an embodiment of the present inventionFor example, the III-V cap layer 112 may be a P-type GaN layer. According to an embodiment of the present invention, the etch stop layer 114 may comprise a metal nitride, such as titanium nitride, and the etch stop layer 114 and the first interlayer dielectric layer 124 may have different etch rates therebetween. According to an embodiment of the present invention, the passivation layer 116 may be a thin dielectric layer with a thickness of 0.5 nm to 10 nm, which may be used to eliminate or reduce surface defects existing on the sidewalls of the III-V channel layer 104 and the top surface of the III-V barrier layer 106, thereby improving the electron mobility of the two-dimensional electron gas region 120. According to an embodiment of the present invention, the passivation layer 116 may be silicon nitride (SiN), silicon oxynitride (SiON), aluminum nitride (AlN), aluminum oxide (Al)₂O₃) Or silicon oxide (SiO)₂) But is not limited thereto. The first interlayer dielectric 124, the second interlayer dielectric 126, and the third interlayer dielectric 154 may have the same or different compositions, such as SiN, AlN, Al₂O₃SiON or SiO₂But is not limited thereto.

Fig. 2 is a schematic top view of a high voltage semiconductor device according to an embodiment of the invention, taken along line a-a' of fig. 1. As shown in fig. 2, the gate electrode 140, the source electrode 144, the first drain electrode 142, and the second drain electrode 148 may be disposed in parallel such that the long axes thereof are parallel to each other. According to an embodiment of the present invention, the gate electrode 140 and the first drain electrode 142 are in the shape of a bar, and the source electrode 144 and the second drain electrode 148 are in the shape of a ring, but not limited thereto. According to an embodiment of the present invention, the gate electrode 140, the source electrode 144, the first drain electrode 142, and the second drain electrode 148 may be arbitrarily selected from a stripe shape or a ring shape. Also, according to an embodiment of the present invention, one of the source electrode 144 and the second drain electrode 148 may have a circular shape, and thus the other of the source electrode 144 and the second drain electrode 148, the first drain electrode 142, and the gate electrode 140 may surround the periphery of the circular electrode to form a concentric electrode.

Fig. 3 is a cross-sectional view of a high voltage semiconductor device having a plurality of drain electrodes according to an embodiment of the invention. The high voltage semiconductor device shown in fig. 2 may be, for example, an enhancement mode hemt 10' having a structure similar to that of the enhancement mode hemt 10 shown in fig. 1. However, the main difference between the embodiment shown in fig. 2 and the embodiment shown in fig. 1 is that the first drain electrode 142 shown in fig. 2 extends into the group III-V barrier layer 106, so that the first drain electrode 142 can more effectively control the electric field distribution (or potential distribution) in the group III-V barrier layer 106 and the group III-V channel layer 104, thereby achieving the effect of reducing the off-current of the high voltage semiconductor device.

Fig. 4 is a cross-sectional view of a high voltage semiconductor device having a plurality of drain electrodes according to an embodiment of the invention. The high voltage semiconductor device shown in fig. 4 may be, for example, an enhancement mode hemt 10 "having a structure similar to that of the enhancement mode hemt 10 shown in fig. 1. However, the main difference between the embodiment shown in fig. 4 and the embodiment shown in fig. 1 is that the enhancement mode hemt 10 "shown in fig. 4 includes a plurality of first drain electrodes 142, 142 'and each of the first drain electrodes 142, 142' may form a schottky contact with an underlying semiconductor layer, such as the III-V barrier layer 106. The first drain electrode 142' may be disposed adjacent to the first drain electrode 142, and bottom surfaces 143 and 143' thereof may be spaced apart from each other by a distance L '_DD. The bottom width W of the first drain electrode 142' may be the same or different from the bottom width W of the first drain electrode 142 according to different requirements. The first drain electrode 142' may be electrically connected to the first and second drain electrodes 142 and 148, for example, by a conductive plug 150' disposed on top of the first drain electrode 142 '. By providing a plurality of first drain electrodes 142, 142', the distribution of the electric field can be more flexibly adjusted.

In order to enable a person skilled in the art to realize the present invention, a method for manufacturing a high voltage semiconductor device according to the present invention is described in detail further below.

FIG. 5 is a high voltage substrate with a III-V channel layer, a III-V barrier layer, a gate structure, and an interlayer dielectric layer disposed thereon according to an embodiment of the inventionA cross-sectional view of a semiconductor device. As shown in fig. 5, at a stage of a process of manufacturing the hemt 20, the substrate 100 may be sequentially stacked with a buffer layer 102, a III-V channel layer 104, a III-V barrier layer 106, a stack structure 160, a passivation layer 116, and a first interlayer dielectric layer 124. Contact holes, such as a gate contact hole 130 and a first drain contact hole 134, may be disposed in the first interlayer dielectric layer 124 to expose the underlying passivation layer 116. According to an embodiment of the invention, each stacked layer on the substrate 100 may be formed by any suitable method, for example, by molecular-beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), Hydride Vapor Phase Epitaxy (HVPE), Atomic Layer Deposition (ALD), or other suitable deposition methods. The buffer layer 102 may include a plurality of sub-semiconductors, and the resistance of the whole buffer layer is higher than that of other layers on the substrate 100. Specifically, the ratio of some elements, such as metal elements, in the buffer layer 102 may gradually change from the substrate 100 to the III-V channel layer 104. For example, for the case where the substrate 100 and the III-V channel layer 104 are a silicon substrate and a GaN layer, respectively, the buffer layer 102 may be aluminum gallium nitride (Al) with graded composition ratio_xGa_1-xN) and decreases in a continuous or step-wise manner from 0.9 to 0.15 in a direction along the substrate 100 toward the III-V channel layer 104.

Fig. 6 is a cross-sectional view of a high voltage semiconductor device having a gate electrode and a first drain electrode disposed in an interlayer dielectric layer according to an embodiment of the invention. As shown in fig. 6, a conductive layer, such as a composite conductive layer including a schottky contact metal, may be formed on the top surface of the first interlayer dielectric 124, in the gate contact hole 130 and in the first drain contact hole 134 by a suitable deposition process. Then, photolithography and etching processes are performed to pattern the conductive layer, thereby forming the gate electrode 140 and the first drain electrode 142. According to an embodiment of the present invention, for the gate contact hole 130 and the first drain contact hole 134 with smaller opening areas, the conductive layer may completely fill the contact hole 130 and the first drain contact hole 134, but is not limited thereto.

A second ild may then be blanket deposited to cover the first ild 124, the gate electrode 140, and the first drain electrode 142.

Fig. 7 is a cross-sectional view of a high voltage semiconductor device having a source contact hole and a second drain contact hole in an interlayer dielectric layer according to an embodiment of the invention. As shown in fig. 8, after forming the second interlayer dielectric layer 126, a source contact hole 132 and a second drain contact hole 136 may be separately formed in the first interlayer dielectric layer 124 and the second interlayer dielectric layer 126 by photolithography and etching processes, wherein the bottom of the source contact hole 132 and the second drain contact hole 136 may penetrate into the III-V channel layer 104, but is not limited thereto. Thereafter, another photolithography and etching process may be performed to form an opening 138 in the second interlayer dielectric layer 126, such that the top surface of the first drain electrode 142 may be exposed from the opening 138.

Fig. 8 is a cross-sectional view of a high voltage semiconductor device having a source electrode and a second drain electrode disposed in an interlayer dielectric layer according to an embodiment of the invention. As shown in fig. 8, a conductive layer, such as a composite conductive layer including an ohmic contact metal, may be formed on the top surface of the second interlayer dielectric layer 126 and within the source contact hole 132, the second drain contact hole 136, and the opening 138 by a suitable deposition process. Thereafter, photolithography and etching processes are performed to pattern the conductive layer, thereby forming the source electrode 144, the field plate 146, the second drain electrode 148, the conductive plug 150, and the conductive line 152. According to an embodiment of the present invention, for the opening 138 with a smaller opening area, the conductive layer may completely fill the opening 138; for the source contact hole 132 and the second drain contact hole 136 with larger opening area, the conductive layer can cover the sidewalls of the contact holes 132, 136, but not limited thereto.

Next, a third interlayer dielectric layer may be deposited on the second interlayer dielectric layer 126, the source electrode 144, the field plate 146, the second drain electrode 148, the conductive plug 150, and the conductive connection line 152 to obtain the hemt 10 shown in fig. 1.

Fig. 9 is a flowchart illustrating a method of fabricating a high voltage semiconductor device according to an embodiment of the invention. As shown in fig. 9, a method 200 of fabricating a high electron mobility transistor according to an embodiment of the present invention may include: step 202: providing a semiconductor substrate, wherein a III-V channel layer, a III-V barrier layer, a III-V cover layer and an interlayer dielectric layer are sequentially stacked on the semiconductor substrate; step 204: forming a gate contact hole and a first drain contact hole in the interlayer dielectric layer; step 206: forming a gate electrode and a first drain electrode respectively in the gate contact hole and the first drain contact hole; step 208: forming a source contact hole and a second drain contact hole in the interlayer dielectric layer; step 210: and forming a source electrode and a second drain electrode respectively in the source contact hole and the second drain contact hole, the second drain electrode being electrically connected to the first drain electrode.

According to the embodiments of the present invention, by providing the first drain electrode and the second drain electrode having bottom surfaces laterally separated from each other, the first drain electrode may form a schottky contact with the underlying semiconductor layer, and the second drain electrode may form an ohmic contact with the underlying semiconductor layer, the distance between the first drain electrode and the gate structure may be arbitrarily set without changing the width of the bottom surface of the first drain electrode, so that not only the distribution of the surface electric field of the high voltage semiconductor device may be improved, but also the off-current of the device may be reduced, and at the same time, the contact area between the bottom surface of the first drain electrode and the underlying semiconductor layer may be prevented from being excessively increased, and the increase of the on-resistance of the high voltage semiconductor device may be prevented.

The above-mentioned embodiments are merely preferred embodiments of the present invention, and all equivalent changes and modifications made by the claims of the present invention should be covered by the scope of the present invention.