阅读说明：本技术 一种具有弧形栅电极的氮化镓高频晶体管及制作方法 (Gallium nitride high-frequency transistor with arc-shaped gate electrode and manufacturing method ) 是由 刘志宏 朱肖肖 张进成 王泽宇 郎英杰 周弘 赵胜雷 张雅超 张苇杭 郝跃 于 2020-04-28 设计创作，主要内容包括：本发明涉及一种具有弧形栅电极的氮化镓高频晶体管及制作方法,包括：晶圆结构；栅电极、源电极和漏电极,所述栅电极、所述源电极和所述漏电极设置于所述晶圆结构上,其中,所述栅电极包括栅脚和设置于所述栅脚上的栅头,所述栅头的体积大于所述栅脚的体积,所述栅头与所述栅脚的连接处为弧形。本发明的晶圆结构为氮化镓高迁移率晶体管外延结构,包括衬底层、复合缓冲区、沟道层和复合势垒区,栅电极采用弧形结构,可提高器件的工作频率、增加器件的击穿电压,使器件具有更低的导通电阻和更高的输出电流。(The invention relates to a gallium nitride high-frequency transistor with an arc-shaped gate electrode and a manufacturing method thereof, wherein the gallium nitride high-frequency transistor comprises the following steps: a wafer structure; the wafer structure comprises a gate electrode, a source electrode and a drain electrode, wherein the gate electrode, the source electrode and the drain electrode are arranged on the wafer structure, the gate electrode comprises a gate pin and a gate head arranged on the gate pin, the volume of the gate head is larger than that of the gate pin, and the joint of the gate head and the gate pin is arc-shaped. The wafer structure is a gallium nitride high-mobility transistor epitaxial structure and comprises a substrate layer, a composite buffer region, a channel layer and a composite barrier region, wherein a gate electrode is of an arc-shaped structure, so that the working frequency of a device can be improved, the breakdown voltage of the device can be increased, and the device has lower on-resistance and higher output current.)

1. A gallium nitride high-frequency transistor having an arc-shaped gate electrode, comprising:

a wafer structure (1);

the wafer structure comprises a gate electrode (2), a source electrode (3) and a drain electrode (4), wherein the gate electrode (2), the source electrode (3) and the drain electrode (4) are arranged on the wafer structure (1), the gate electrode (2) comprises a gate pin (21) and a gate head (22) arranged on the gate pin (21), the volume of the gate head (22) is larger than that of the gate pin (21), and the joint of the gate head (22) and the gate pin (21) is arc-shaped.

2. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 1, characterized in that the cross-sectional area from the top surface of the gate head (22) to the bottom surface of the gate head (22) is gradually reduced, and the side surface of the gate head (22) is arc-shaped.

3. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 2, characterized in that the junction of the top surface of the gate head (22) and the gate head (22) is arc-shaped.

4. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 2, characterized in that the cross-sectional area from the top surface of the gate leg (21) to the bottom surface of the gate leg (21) is gradually reduced, and the side surface of the gate leg (21) is arc-shaped.

5. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 1, characterized in that the height of the gate head (22) is equal to or greater than the height of the gate foot (21).

6. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 5, characterized in that the height of the gate leg (21) is 10nm to 300 nm.

7. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 5, characterized in that the height of the gate head (22) is 10nm to 800 nm.

8. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 1, characterized in that the material of the gate electrode (2) is one of nickel/gold, titanium/gold or oxide/nickel/gold.

9. The gallium nitride high-frequency transistor with an arc-shaped gate electrode according to claim 1, wherein the source electrode (3) is made of one of titanium/aluminum/random metal/gold, titanium/random metal or tantalum/random metal, and the drain electrode (4) is made of one of titanium/aluminum/random metal/gold, titanium/random metal or tantalum/random metal.

10. A method for manufacturing a gallium nitride high-frequency transistor with an arc-shaped gate electrode is characterized by comprising the following steps:

manufacturing a source electrode (3) and a drain electrode (4) on the wafer structure (1);

coating a first electron beam photoresist (1a) on the wafer structure (1);

coating a second electron beam photoresist (1b) on the first electron beam photoresist (1a), wherein the photosensitivity of the second electron beam photoresist (1b) is greater than that of the first electron beam photoresist (1 a);

exposing, developing and baking the wafer structure (1) coated with the first electron beam photoresist (1a) and the second electron beam photoresist (1b) twice, and forming a gate electrode structure (1c) on the first electron beam photoresist (1a) and the second electron beam photoresist (1 b);

depositing a gate electrode material in the gate electrode structure (1 c);

and stripping the first electron beam photoresist (1a) and the second electron beam photoresist (1b) to obtain a gate electrode (2), wherein the gate electrode (2) comprises a gate pin (21) and a gate head (22) arranged on the gate pin (21), the volume of the gate head (22) is larger than that of the gate pin (21), and the joint of the gate head (22) and the gate pin (21) is arc-shaped.

Technical Field

The invention belongs to the technical field of semiconductor devices, and particularly relates to a gallium nitride high-frequency transistor with an arc-shaped gate electrode and a manufacturing method thereof.

Background

With the development of microelectronic technology, third generation wide bandgap semiconductor materials represented by gallium nitride have larger bandgap, higher critical breakdown electric field, higher electron saturation drift velocity, stable chemical properties, high temperature resistance, radiation resistance and other physical properties, electronic devices manufactured by using gallium nitride materials can further reduce chip area, improve working frequency, improve working temperature, reduce on-resistance, improve breakdown voltage and the like, and gallium nitride materials have great potential in the aspect of manufacturing microwave devices. Gallium nitride and aluminum gallium nitrogen, indium aluminum nitrogen and the like which have the same material system with the gallium nitride have high polarization coefficients, a heterostructure formed by the gallium nitride and the aluminum gallium nitrogen or the indium aluminum nitrogen with the forbidden band width larger than that of the gallium nitride can form two-dimensional electron gas better, and more than 1500cm can be obtained at room temperature²The electron mobility of the/V.s reaches 1.5 × 10cm⁷Saturated electron velocity sum of more than 1 × 10 per second¹³cm^-2The two-dimensional electron gas concentration of the semiconductor device, so that high-speed Schottky Barrier Diode (SBD) and High Electron Mobility Transistor (HEMT) devices developed based on gallium nitride materials can have lower on-resistance and higher output current. In addition, the higher critical breakdown field strength of the gallium nitride material can enable the electronic device to have higher breakdown voltageThe voltage is passed, so that the device can work under higher working voltage, the microwave output power density is higher, and compared with a silicon or gallium arsenide microwave transistor with the same output power, the gallium nitride transistor has higher power addition efficiency and lower energy loss.

Important factors affecting the highest oscillation frequency are the gate leg length and the metal resistance of the gate electrode, which is inversely proportional to the cross-sectional area of the gate metal, that is, the length of the gate electrode. Increasing the operating frequency of the transistor requires a reduction in the gate leg length, which, however, increases the metal resistance of the gate electrode. At present, the shape of the gate electrode is designed to improve the operating frequency and breakdown voltage of the gan high-frequency transistor by the following main methods: the asymmetric gate electrode is characterized in that the voltage drop of the transistor in a normal working state is mainly concentrated between the gate and the drain, so that the length of a gate head of the T-shaped gate electrode close to the drain end is increased, the field plate effect of the T-shaped gate electrode can be enhanced, the electric field peak intensity of the gate electrode close to the drain end is effectively reduced, and the breakdown voltage is increased. However, this method has disadvantages in that the length of the gate head becomes wide and an additional parasitic capacitance becomes large, thereby affecting the cutoff frequency and the highest oscillation frequency. The gravity center deviation of the asymmetric gate type gate electrode also makes the gate electrode manufactured by the double-layer glue stripping manufacturing method easier to collapse, thereby influencing the manufacturing yield of the gate electrode. The increase of the width of the gate head can also increase the gate-drain distance, thereby enhancing the drain access resistance of the device and influencing the cut-off frequency, the on-resistance and the power added efficiency of the device. And in order to increase the suspension height of the gate head, reduce the parasitic capacitance between the gate head of the T-shaped gate electrode and the conductive channel of the microwave device and keep the stability of the T-shaped gate electrode, the gate electrode can be made into a Y-shaped structure, namely the suspension part of the gate head is not horizontal but inclined upwards. The Y-shaped gate electrode effectively reduces high parasitic capacitance brought by the T-shaped gate electrode. The disadvantage is that the breakdown voltage is improved compared with the T-shaped gate, but the electric field intensity peak of the edge of the gate electrode is still higher, and the breakdown voltage is still lower. Therefore, most high frequency transistors use a technique called "T-gate" to add a gate head to the gate leg, thereby achieving a thinner gate leg while maintaining a wider gate head and lower metal resistance of the gate electrode.

The introduction of the T-shaped gate also has some disadvantages, and the wider gate head structure introduces additional parasitic capacitance, thereby causing the cut-off frequency and the highest oscillation frequency of the transistor to be reduced; to reduce the additional parasitic capacitance, the height of the gate leg needs to be increased, which can make the gate electrode unstable and easily collapse.

Disclosure of Invention

In order to solve the above problems in the prior art, the present invention provides a gallium nitride high frequency transistor with an arc-shaped gate electrode and a manufacturing method thereof. The technical problem to be solved by the invention is realized by the following technical scheme:

a gallium nitride high-frequency transistor having an arc-shaped gate electrode, comprising:

a wafer structure;

the wafer structure comprises a gate electrode, a source electrode and a drain electrode, wherein the gate electrode, the source electrode and the drain electrode are arranged on the wafer structure, the gate electrode comprises a gate pin and a gate head arranged on the gate pin, the volume of the gate head is larger than that of the gate pin, and the joint of the gate head and the gate pin is arc-shaped.

In one embodiment of the invention, the cross-sectional area from the top surface of the gate head to the bottom surface of the gate head is gradually reduced, and the side surface of the gate head is arc-shaped.

In one embodiment of the invention, the junction between the top surface of the grid head and the grid head is arc-shaped.

In one embodiment of the present invention, the cross-sectional area from the top surface of the grid leg to the bottom surface of the grid leg is gradually reduced, and the side surface of the grid leg is arc-shaped.

In one embodiment of the invention, the height of the gate head is greater than or equal to the height of the gate foot.

In one embodiment of the invention, the height of the gate pin is 10 nm-300 nm.

In one embodiment of the invention, the height of the gate head is 10nm to 800 nm.

In one embodiment of the present invention, the gate electrode is made of one of nickel/gold, titanium/gold, or oxide/nickel/gold.

In one embodiment of the present invention, the source electrode is made of one of titanium/aluminum/metal/gold, titanium/metal or tantalum/metal, and the drain electrode is made of one of titanium/aluminum/metal/gold, titanium/metal or tantalum/metal.

A method for manufacturing a gallium nitride high-frequency transistor with an arc-shaped gate electrode comprises the following steps:

manufacturing a source electrode (3) and a drain electrode (4) on the wafer structure (1);

coating a first electron beam photoresist (1a) on the wafer structure (1);

coating a second electron beam photoresist (1b) on the first electron beam photoresist (1a), wherein the photosensitivity of the second electron beam photoresist (1b) is greater than that of the first electron beam photoresist (1 a);

exposing, developing and baking the wafer structure (1) coated with the first electron beam photoresist (1a) and the second electron beam photoresist (1b) twice, and forming a gate electrode structure (1c) on the first electron beam photoresist (1a) and the second electron beam photoresist (1 b);

depositing a gate electrode material in the gate electrode structure (1 c);

and stripping the first electron beam photoresist (1a) and the second electron beam photoresist (1b) to obtain a gate electrode (2), wherein the gate electrode (2) comprises a gate pin (21) and a gate head (22) arranged on the gate pin (21), the volume of the gate head (22) is larger than that of the gate pin (21), and the joint of the gate head (22) and the gate pin (21) is arc-shaped.

The invention has the beneficial effects that:

the invention comprises a wafer structure, a gate electrode, a source electrode and a drain electrode, wherein the gate electrode, the source electrode and the drain electrode are all arranged on the wafer structure, the gate electrode comprises a gate head and a gate pin, the gate head is arranged on the gate pin, the volume of the gate head is larger than that of the gate pin, and the joint of the gate head and the gate pin is arc-shaped.

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Drawings

FIG. 1 is a schematic cross-sectional view of a GaN high-frequency transistor having an arc-shaped gate electrode according to an embodiment of the invention;

FIG. 2 is a schematic cross-sectional view of a gate electrode of a GaN high-frequency transistor having an arc-shaped gate electrode according to an embodiment of the invention;

FIG. 3 is a schematic structural diagram of a wafer structure of a GaN high-frequency transistor with an arc-shaped gate electrode according to an embodiment of the invention;

FIG. 4 is a schematic structural diagram of another wafer structure of a GaN high-frequency transistor with an arc-shaped gate electrode according to an embodiment of the invention;

FIGS. 5a to 5h are schematic diagrams illustrating a method for fabricating a wafer structure of a GaN high-frequency transistor having an arc-shaped gate electrode according to an embodiment of the invention;

fig. 6 to fig. 13 are schematic diagrams of a method for manufacturing a gate electrode of a gan high-frequency transistor having an arc-shaped gate electrode according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.