阅读说明：本技术 一种高耐压的GaN基HEMT器件及其制备方法 (High-voltage-resistance GaN-based HEMT device and preparation method thereof ) 是由 王洪 周昀璐 高升 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种高耐压的GaN基HEMT器件及其制备方法。所述器件AlGaN/GaN异质结外延层、源级电极、漏极电极、第一钝化层、T型栅电极、第一离散场板、第二钝化层、第二离散场板和漏场板。本发明采用呈一定斜角分布的双离散场板结构和漏场板结构,优化了沟道电场分布,降低了电场峰值,抑制了高温退火后漏电级金属尖峰造成器件提前击穿的影响,提高了器件的击穿电压；与此同时,由于第一离散场板与栅电极,以及第二离散场板与漏场板分别在同一步工艺中生长,简化了制备方法,使得所述器件的制备方法可重复性高,适用于高压大功率电力电子器件的产业化应用。(The invention discloses a high-voltage-resistant GaN-based HEMT device and a preparation method thereof. The device comprises an AlGaN/GaN heterojunction epitaxial layer, a source electrode, a drain electrode, a first passivation layer, a T-shaped gate electrode, a first discrete field plate, a second passivation layer, a second discrete field plate and a drain field plate. The invention adopts the double-discrete field plate structure and the leakage field plate structure which are distributed at a certain oblique angle, optimizes the electric field distribution of the channel, reduces the electric field peak value, inhibits the influence of the leakage level metal peak on the early breakdown of the device after high-temperature annealing, and improves the breakdown voltage of the device; meanwhile, the first discrete field plate and the gate electrode, and the second discrete field plate and the drain field plate are respectively grown in the same process, so that the preparation method is simplified, the preparation method of the device has high repeatability, and the device is suitable for industrial application of high-voltage high-power electronic devices.)

1. A high-withstand-voltage GaN-based HEMT device is characterized by comprising an AlGaN/GaN heterojunction epitaxial layer (101), a source electrode (102), a drain electrode (103), a first passivation layer (104), a T-shaped gate electrode (105), a first discrete field plate (106), a second passivation layer (107), a second discrete field plate (108) and a drain field plate (109);

the AlGaN/GaN heterojunction epitaxial layer (101) is of a boss structure, the protruding part of the boss structure is an active region, two ends of the upper surface of the active region are respectively connected with a source electrode (102) and a drain electrode (103), and a gate electrode (105) is arranged on the active region close to one side of the source electrode (102); the drain field plate (109) is arranged on the drain electrode (103); a first passivation layer (104) covers the surface of the upper surface of the AlGaN/GaN heterojunction epitaxial layer (101) except for the source electrode (102), the gate electrode (105) and the drain electrode (103);

a first discrete field plate (106) is disposed on the first passivation layer (104) between the gate electrode (105) and the drain electrode (103); a second passivation layer (107) covers the first passivation layer (104), the gate electrode (105) and the surface of the first discrete field plate (106), achieving isolation between the first discrete field plate (106) and the second discrete field plate (108); a second discrete field plate (108) is disposed on the second passivation layer (107) above and between the first discrete field plate (106) and the drain electrode (103).

2. The high withstand voltage GaN-based HEMT device according to claim 1, wherein the gate electrode (105) has a T-type field plate structure, and portions of the first passivation layer (104) exposed therefrom extend to both sides, respectively.

3. The high withstand voltage GaN-based HEMT device according to claim 1, wherein the drain field plate (109) is positioned next to the portion of the drain electrode (103) exposing the second passivation layer (107) between the portion of the drain electrode (103) exposing the second passivation layer (107) and the second discrete field plate (108).

4. The high-withstand-voltage GaN-based HEMT device according to claim 1, wherein the central connection line of the first discrete field plate (106) and the second discrete field plate (108) is at an oblique angle to the active region surface.

5. The high withstand voltage GaN-based HEMT device according to claim 1, wherein the first discrete field plate (106) and the second discrete field plate (108) are equal in length and 1-3 μm.

6. A method of producing the high withstand voltage GaN-based HEMT device according to any one of claims 1 to 5, comprising the steps of:

s1, forming an independent active region by isolating and etching the AlGaN/GaN heterojunction epitaxial layer (101), and depositing a source electrode (102) and a drain electrode (103) on the active region to form ohmic contact;

s2, depositing a first passivation layer material on the source electrode (102), the drain electrode (103) and the area of the upper surface of the AlGaN/GaN heterojunction epitaxial layer (101) except the area where the source electrode (102) and the drain electrode (103) are connected, and forming a first passivation layer (104);

s3, defining a gate opening photoetching window of the gate electrode (105), and etching the first passivation layer (104) through an etching process to expose the contact part of the AlGaN/GaN heterojunction epitaxial layer (101) and the gate electrode (105);

s4, metal deposition lithography windows defining the gate electrode (105) and the first discrete field plate (106), depositing the gate electrode (105) and the first discrete field plate (106);

s5, depositing a second passivation layer material to form a second passivation layer (107);

s6, defining photoetching windows of the source electrode (102) and the drain electrode (103), and etching the first passivation layer (104) and the second passivation layer (107) through an etching process to expose the source electrode (102) and the drain electrode (103);

and S7, defining photoetching windows of the second discrete field plate (108) and the drain field plate (109), and depositing the second discrete field plate (108) and the drain field plate (109) to obtain the high-voltage-resistant GaN-based HEMT device.

7. The method for manufacturing a high withstand voltage GaN-based HEMT device according to claim 6, wherein in step S4, the gate electrode (105) and the first discrete field plate (106) are grown in the same process, and the materials are identical and are both Ni/Au.

8. The method for manufacturing a high withstand voltage GaN-based HEMT device according to claim 6, wherein in step S7, the drain field plate (109) and the second discrete field plate (108) are grown in the same process step, and the materials are consistent and are both Ti/Al/Ti/Au.

Technical Field

The invention belongs to the technical field of semiconductors, and particularly relates to a high-voltage-resistant GaN-based HEMT device and a preparation method thereof.

Background

Wide bandgap iii-nitride semiconductor materials are of interest to researchers in many fields due to their excellent physical properties, and electronic devices thereof have been widely used in optoelectronic integration, ultra-high speed microelectronic devices and integrated circuits, and have been rapidly developed in recent years. Due to the excellent characteristics of wide forbidden band, large critical electric field, high electron mobility, good thermal conductivity and the like, gallium nitride (GaN) meets the requirements of next-generation electronic equipment on higher power, higher frequency, smaller volume and worse high-pressure and high-temperature operation of power devices. Particularly in the field of intelligent quick charging, the quick charger for the GaN power device has the advantages of higher power, smaller volume and higher charging speed. GaN-based power devices are the core of next-generation power devices, and particularly AlGaN/GaN heterojunction High Electron Mobility Transistors (HEMTs) have been developed rapidly in recent decades and have been widely applied to the fields of new energy automobiles, rail transit, intelligent rapid charging and the like. In industrial application, the reliability of the GaN-based HEMT power device is particularly critical, wherein the breakdown voltage is a key index for measuring the reliability of the GaN-based HEMT power device. In order to increase the breakdown voltage of the device, the field plate structure is most commonly used at present. The field plate structure smoothes the peak value of an electric field between electrodes of the GaN-based HEMT device, inhibits the formation of a virtual grid and obviously improves the breakdown voltage of the GaN-based HEMT device. The scholars (Deguchi, Kamada, Yamashita et al.high-voltage AlGaN/GaN HFETs by using graded field devices [ J ]. Electronics letters,2012,48,2:109-110.) developed a process for forming a linear gradient distribution of SiO2, and prepared a double-sided slant gate field plate with a slant angle of 23 degrees, and the breakdown voltage of the device reached 830V.

The existing inclined grid field plate preparation process is complex and the inclination angle is not easy to control. The oblique distribution of multiple discrete field plates means that the distance between the discrete field plates and the channel is increased along with the increase of the distance from the gate, so that the electric field at the channel tends to be uniform, and the oblique gate field plates have the same effect. And the inclination angle of the discrete field plate can be flexibly controlled and prepared by controlling the growth thickness of the passivation layer.

In conclusion, the discrete field plate structure can significantly improve the breakdown voltage of the device. However, the prior discrete field plate preparation process is complex and high in preparation cost.

Disclosure of Invention

The invention provides a high-voltage-resistant GaN-based HEMT device, which adopts an optimized double-discrete field plate structure, and a first discrete field plate and a gate electrode, as well as a second discrete field plate and a drain field plate respectively grow in the same process in the preparation process, thereby simplifying the preparation method, ensuring that the preparation method of the device has high repeatability, preparing the high-voltage-resistant GaN-based HEMT device and being suitable for industrial application of high-voltage high-power electronic devices.

The purpose of the invention is realized by at least one of the following technical solutions.

A high-voltage-resistant GaN-based HEMT device comprises an AlGaN/GaN heterojunction epitaxial layer, a source electrode, a drain electrode, a first passivation layer, a T-shaped gate electrode, a first discrete field plate, a second passivation layer, a second discrete field plate and a drain field plate;

the AlGaN/GaN heterojunction epitaxial layer is of a boss structure, the protruding part of the boss structure is an active region, two ends of the upper surface of the active region are respectively connected with a source electrode and a drain electrode, and a gate electrode is arranged on the active region close to one side of the source electrode; the drain field plate is arranged on the drain electrode; the first passivation layer covers the surface of the part of the upper surface of the AlGaN/GaN heterojunction epitaxial layer except the source electrode, the gate electrode and the drain electrode;

the first discrete field plate is arranged on the first passivation layer and positioned between the gate electrode and the drain electrode; the second passivation layer covers the surfaces of the first passivation layer, the gate electrode and the first discrete field plate, and isolation between the first discrete field plate and the second discrete field plate is realized; the second discrete field plate is arranged on the second passivation layer and is positioned above the first discrete field plate and the drain electrode.

Furthermore, the gate electrode is of a T-shaped field plate structure, and the parts of the gate electrode, which are exposed out of the first passivation layer, extend towards two sides respectively.

Further, the drain field plate is arranged between the portion of the drain electrode exposing the second passivation layer and the second discrete field plate and is close to the portion of the drain electrode exposing the second passivation layer.

Further, the central connecting line of the first discrete field plate and the second discrete field plate is oblique to the surface of the active region.

Further, the length of the first discrete field plate is equal to that of the second discrete field plate, and is 1-3 μm.

A method for preparing a high-withstand-voltage GaN-based HEMT device is characterized by comprising the following steps:

s1, forming an independent active region by isolating and etching the AlGaN/GaN heterojunction epitaxial layer, and depositing a source electrode and a drain electrode on the active region to form ohmic contact;

s2, depositing a first passivation layer material on the source electrode, the drain electrode and the region outside the AlGaN/GaN heterojunction epitaxial layer, wherein the upper surface of the source electrode is connected with the source electrode and the drain electrode, and forming a first passivation layer;

s3, defining a gate opening photoetching window of the gate electrode, and etching the first passivation layer through an etching process to expose the contact part of the AlGaN/GaN heterojunction epitaxial layer and the gate electrode;

s4, defining a gate electrode and a metal deposition photoetching window of the first discrete field plate, and depositing the gate electrode and the first discrete field plate;

s5, depositing a second passivation layer material to form a second passivation layer;

s6, defining photoetching windows of the source electrode and the drain electrode, and etching the first passivation layer and the second passivation layer through an etching process to expose the source electrode and the drain electrode;

and S7, defining a second discrete field plate and a drain field plate photoetching window, and depositing the second discrete field plate and the drain field plate to obtain the high-voltage-resistant GaN-based HEMT device.

Further, in step S4, the gate electrode and the first discrete field plate are grown in the same process, and the materials are the same and both Ni/Au.

Further, in step S7, the drain field plate and the second discrete field plate are grown in the same process, and the materials are the same and are both Ti/Al/Ti/Au.

Compared with the prior art, the invention has the following beneficial effects and advantages:

the invention adopts the double-discrete field plate structure and the leakage field plate structure which are distributed at a certain oblique angle, optimizes the electric field distribution of the channel, reduces the electric field peak value, inhibits the influence of the leakage level metal peak on the early breakdown of the device after high-temperature annealing, and improves the breakdown voltage of the device; meanwhile, the first discrete field plate and the gate electrode, and the second discrete field plate and the drain field plate are respectively grown in the same process, so that the preparation method is simplified, the preparation method of the device has high repeatability, and the device is suitable for industrial application of high-voltage high-power electronic devices. Through a breakdown characteristic test, when the gate-source voltage is-15V, the device is in a completely closed state, the breakdown voltage of the device with the double discrete field plates can reach 1257V, and compared with a device without the double discrete field plates (861V), the breakdown voltage is improved by 45.99%.

Drawings

Fig. 1 is a flowchart of a method for manufacturing a high withstand voltage GaN-based HEMT device according to an embodiment;

fig. 2 to 8 are schematic views in the process of manufacturing a high withstand voltage GaN-based HEMT device provided by the embodiment;

fig. 9 is a graph comparing breakdown voltage curves of the high withstand voltage GaN-based HEMT device prepared in example.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art.

Example (b):

in this embodiment, a high-withstand-voltage GaN-based HEMT device, as shown in fig. 8, includes an AlGaN/GaN heterojunction epitaxial layer 101, a source electrode 102, a drain electrode 103, a first passivation layer 104, a T-shaped gate electrode 105, a first discrete field plate 106, a second passivation layer 107, a second discrete field plate 108, and a drain field plate 109;

the AlGaN/GaN heterojunction epitaxial layer 101 is of a boss structure, the protruding part of the boss structure is an active region, two ends of the upper surface of the active region are respectively connected with a source electrode 102 and a drain electrode 103, and a gate electrode 105 is arranged on the active region close to one side of the source electrode 102; the drain field plate 109 is provided on the drain electrode 103; a first passivation layer 104 is covered on the surface of the portion of the upper surface of the AlGaN/GaN heterojunction epitaxial layer 101 excluding the source electrode 102, the gate electrode 105, and the drain electrode 103;

a first discrete field plate 106 is disposed on the first passivation layer 104 between the gate electrode 105 and the drain electrode 103; a second passivation layer 107 covers the first passivation layer 104, the gate electrode 105 and the surface of the first discrete field plate 106, achieving isolation between the first discrete field plate 106 and the second discrete field plate 108; a second discrete field plate 108 is disposed on the second passivation layer 107 over and between the first discrete field plate 106 and the drain electrode 103.

In this embodiment, the gate electrode 105 has a T-shaped field plate structure, and the portions of the first passivation layer 104 exposed extend to both sides.

In this embodiment, the drain field plate 109 is closely attached to the portion of the drain electrode 103 exposing the second passivation layer 107, and is located between the portion of the drain electrode 103 exposing the second passivation layer 107 and the second discrete field plate 108.

In this embodiment, the central connection line of the first discrete field plate 106 and the second discrete field plate 108 forms an oblique angle with the active region surface.

In this embodiment, the lengths of the first discrete field plates 106 and the second discrete field plates 108 are equal and are 1-3 μm.

A method of manufacturing a high withstand voltage GaN-based HEMT device, as shown in fig. 1, comprising the steps of:

s1, as shown in FIG. 2, the AlGaN/GaN heterojunction epitaxial layer 101 is isolated and etched to form an independent active region, and a source electrode 102 and a drain electrode 103 are deposited on the active region to form ohmic contact;

s2, as shown in fig. 3, depositing a first passivation layer 104 on the source electrode 102, the drain electrode 103 and the AlGaN/GaN heterojunction epitaxial layer 101, in the region outside the region where the surface connects the source electrode 102 and the drain electrode 103;

s3, defining a gate opening photoetching window of the gate electrode 105, and etching the first passivation layer 104 through an etching process to expose the contact part of the AlGaN/GaN heterojunction epitaxial layer 101 and the gate electrode 105;

s4, metal deposition lithography windows defining the gate electrode 105 and the first discrete field plates 106, depositing the gate electrode 105 and the first discrete field plates 106;

in this embodiment, the gate electrode 105 and the first discrete field plate 106 are grown in the same process, and the materials are consistent and are both Ni/Au.

S5, as shown in fig. 6, depositing a second passivation layer to form a second passivation layer 107;

s6, as shown in fig. 7, defining photolithography windows of the source electrode 102 and the drain electrode 103, and etching the first passivation layer 104 and the second passivation layer 107 by an etching process to expose the source electrode 102 and the drain electrode 103;

s7, as shown in fig. 8, defining the second discrete field plate 108 and the drain field plate 109, and depositing the second discrete field plate 108 and the drain field plate 109 to obtain the high-withstand-voltage GaN-based HEMT device;

in this embodiment, the drain field plate 109 and the second discrete field plate 108 are grown in the same process, and the materials are the same and are Ti/Al/Ti/Au.

Fig. 9 is a breakdown characteristic diagram of the device corresponding to this embodiment, when the gate-source voltage is-15V, the device is in a completely closed state, the breakdown voltage of the device with dual discrete field plates of the present invention can reach 1257V, and compared with the device without dual discrete field plates (861V), the breakdown voltage is improved by 45.99%.

The above examples are only preferred embodiments of the present invention, which are intended to be illustrative and not limiting, and those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention.