阅读说明：本技术 N极性AlGaN/GaN HEMT器件及其生长方法 (N-polar AlGaN/GaN HEMT device and growth method thereof ) 是由 付羿 周名兵 于 2020-12-24 设计创作，主要内容包括：本发明提供了一种N极性AlGaN/GaN HEMT器件及其生长方法,其中,N极性AlGaN/GaN HEMT器件的外延结构,从下至上依次包括硅衬底层、缓冲层、极性面转换层、耐压层、势垒层及沟道层,其中,极性面转换层为掺杂Mg的GaN层,掺杂浓度为1E20/cm～3～1E21/cm～3。其在缓冲层和耐压层之间添加一层极性面转换层,以此将耐压层及以上的沟道层和势垒层的极性从镓极性转变为氮极性,实现N极性AlGaN/GaN HEMT器件外延结构的制备,结构简单易实现,且具备低接触电阻和强栅控能力。(The invention provides an N-polarity AlGaN/GaN HEMT device and a growth method thereof, wherein an epitaxial structure of the N-polarity AlGaN/GaN HEMT device sequentially comprises a silicon substrate layer, a buffer layer, a polarity face conversion layer, a pressure-resistant layer, a barrier layer and a channel layer from bottom to top, wherein the polarity face conversion layer is a GaN layer doped with Mg, and the doping concentration is 1E20/cm 3 ～1E21/cm 3 . A polar surface conversion layer is added between a buffer layer and a voltage-withstanding layer, so that the polarity of the voltage-withstanding layer and the channel layer and the barrier layer above the voltage-withstanding layer is changed from gallium polarity to nitrogen polarity, the preparation of an epitaxial structure of an N-polarity AlGaN/GaN HEMT device is realized, the structure is simple and easy to realize, and the low-contact resistance and strong gate control capability are realized.)

1. The epitaxial structure of the N-polarity AlGaN/GaN HEMT device is characterized by sequentially comprising a silicon substrate layer, a buffer layer, a polarity face conversion layer, a voltage-resistant layer, a barrier layer and a channel layer from bottom to top, wherein the polarity face conversion layer is a GaN layer doped with Mg, and the doping concentration is 1E20/cm³～1E21/cm³。

2. The epitaxial structure of claim 1, wherein the polar plane conversion layer has a thickness of 200to 1000 nm.

3. The epitaxial structure of claim 1,

the pressure-resistant layer is a GaN layer doped with carbon or iron, and the thickness of the pressure-resistant layer is 1000-10000 nm; and/or the presence of a gas in the gas,

the barrier layer is Al_xGa_1-xN layer, 0.1<x<0.4, and the thickness is 10-40 nm; and/or the presence of a gas in the gas,

the channel layer is an unintentional doped GaN layer and has a thickness of 100-1000 nm.

4. The epitaxial structure of any of claims 1-3 further comprising an AlGaN cap layer grown on the surface of the channel layer.

5. The epitaxial structure of claim 4, wherein the AlGaN cap layer has a thickness of 0to 100nm and an Al composition of 0.01 to 0.2.

6. A preparation method of an epitaxial structure of an N-polarity AlGaN/GaN HEMT device is characterized by comprising the following steps:

growing a buffer layer on the surface of the silicon substrate layer;

growing a polar surface conversion layer on the surface of the buffer layer, wherein the polar surface conversion layer is a GaN layer doped with Mg, and the doping concentration is 1E20/cm³～1E21/cm³；

And sequentially growing a pressure-resistant layer, a barrier layer and a channel layer on the surface of the polar surface conversion layer to finish the preparation of the epitaxial structure.

7. The method of preparing an epitaxial structure according to claim 6, wherein the thickness of the polar plane conversion layer is 200to 1000 nm.

8. A method of preparing an epitaxial structure according to claim 6,

the pressure-resistant layer is a GaN layer doped with carbon or iron, and the thickness of the pressure-resistant layer is 1000-10000 nm; and/or the presence of a gas in the gas,

the barrier layer is Al_xGa_1-xN layer, 0.1<x<0.4, and the thickness is 10-40 nm; and/or the presence of a gas in the gas,

the channel layer is an unintentional doped GaN layer and has a thickness of 100-1000 nm.

9. The method for preparing an epitaxial structure according to any of claims 6 to 8, further comprising, after growing a pressure-resistant layer, a barrier layer and a channel layer on the surface of the polar plane conversion layer in this order:

and growing an AlGaN cap layer on the surface of the channel layer.

10. The method for preparing an epitaxial structure according to claim 9, wherein the AlGaN cap layer has a thickness of 0to 100nm and an Al composition of 0.01 to 0.2.

Technical Field

The invention relates to the technical field of semiconductors, in particular to an N-polarity AlGaN/GaN HEMT device and a growth method thereof.

Background

The AlGaN/GaN-based HEMT has the advantages of high breakdown voltage, high electron saturation rate, high area density, high mobility and two-dimensional electron gas and the like, so that the AlGaN/GaN-based HEMT is widely applied to the fields of high-frequency and high-power switches and radio frequencies. AlGaN/GaN HEMT devices that have been commercialized are generally of Ga (gallium) polarity. Currently, N-polarity AlGaN/GaN HEMTs are generally grown on a C (carbon) -plane SiC substrate or a sapphire substrate, and research on growing N-polarity AlGaN/GaN HEMTs on a silicon substrate is less.

Disclosure of Invention

In order to overcome the defects, the invention provides the N-polarity AlGaN/GaN HEMT device and the growth method thereof, which are beneficial to realizing smaller source-drain contact resistance and obtaining stronger grid control capability.

The technical scheme provided by the invention is as follows:

on one hand, the epitaxial structure of the N-polarity AlGaN/GaN HEMT device comprises a silicon substrate layer, a buffer layer, a polarity face conversion layer, a voltage-withstanding layer, a barrier layer and a channel layer from bottom to top in sequence, wherein the polarity face conversion layer is a GaN layer doped with Mg, and the doping concentration is 1E20/cm³～1E21/cm³。

On the other hand, the preparation method of the epitaxial structure of the N-polarity AlGaN/GaN HEMT device comprises the following steps:

growing a buffer layer on the surface of the silicon substrate layer;

growing a polar surface conversion layer on the surface of the buffer layer, wherein the polar surface conversion layer is a GaN layer doped with Mg, and the doping concentration is 1E20/cm³～1E21/cm³；

And sequentially growing a pressure-resistant layer, a barrier layer and a channel layer on the surface of the polar surface conversion layer to finish the preparation of the epitaxial structure.

According to the N-polarity AlGaN/GaN HEMT device and the growth method thereof, the polarity face conversion layer is added between the buffer layer and the pressure-resistant layer, so that the polarity of the pressure-resistant layer and the channel layer and the barrier layer above the pressure-resistant layer is changed from gallium polarity to nitrogen polarity, the preparation of the epitaxial structure of the N-polarity AlGaN/GaN HEMT device is realized, compared with the HEMT with Ga polarity, ohmic contact of the N (nitrogen) polarity HEMT can be directly manufactured on the GaN layer, and the realization of smaller source and drain contact resistance is facilitated. The cut gate can be made on the GaN channel layer to obtain stronger gate control capability. If a layer of AlGaN grows on the GaN channel layer, two-dimensional electron devices in the channel layer can be exhausted, and the enhancement device can be simply realized.

Drawings

FIG. 1 is a schematic view of an epitaxial structure of an N-polar AlGaN/GaN HEMT device according to an embodiment of the present invention;

fig. 2 is a schematic view of an epitaxial structure of an N-polar AlGaN/GaN HEMT device according to another embodiment of the present invention.

Detailed Description

In order to more clearly illustrate the embodiment of the present invention or the technical solutions in the prior art, the following description will explain embodiments of the present invention with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.

In a first embodiment of the present invention, an epitaxial structure of an N-polarity AlGaN/GaN HEMT device, as shown in fig. 1, sequentially includes, from bottom to top, a silicon substrate layer 101, a buffer layer 102, a polarity plane conversion layer 103, a voltage withstanding layer 104, a barrier layer 105, and a channel layer 106, where the polarity plane conversion layer 103 is a GaN layer doped with Mg and has a doping concentration of 1E20/cm³～1E21/cm³The thickness is 200to 1000 nm.

The buffer layer 102 includes buffer layers of AlN, AlN/AlGaN, and the like to release stress and transition to a subsequent voltage-proof layer. The voltage-resistant layer 104 is a carbon-doped (including inner-doped and outer-doped) or iron-doped GaN layer, and the thickness is 1000-10000 nm. The barrier layer 105 is Al_xGa_1-xN layer, 0.1<x<0.4 and a thickness of 10 to 40 nm. The channel layer 106 is an unintentionally doped high-quality GaN layer (uid-GaN layer) with a thickness of 100to 1000 nm. In the epitaxial structure, a polarity plane conversion layer is added between the buffer layer 102 and the voltage-withstanding layer 104, so that the polarity of the voltage-withstanding layer 104 and the channel layer 106 and the barrier layer 105 above the voltage-withstanding layer is changed from the gallium polarity to the nitrogen polarity.

In another embodiment, as shown in fig. 2, in the epitaxial structure, besides the silicon substrate layer 201, the buffer layer 202, the polar plane conversion layer 203, the voltage-withstanding layer 204, the barrier layer 205 and the channel layer 206, an AlGaN cap layer 207 is grown on the surface of the channel layer to deplete two-dimensional electrons in the channel layer, so that an enhancement mode HEMT device is realized easily. In the layer structure, the thickness of the AlGaN cap layer 207 is 0to 100nm, and the Al component is 0.01 to 0.2.

The preparation of the above example is illustrated below by 2 examples:

the first embodiment is as follows:

firstly, will be straightPlacing a silicon substrate with a diameter of 150mm (111) in MOCVD reaction chamber, and performing high temperature H under the conditions of 70torr pressure and 1050 deg.C₂Processing, removing surface oxide; then, growing a 800nm AlN/AlGaN multilayer buffer layer on the surface of the silicon substrate under the pressure of 70torr and the temperature of 1000 ℃, wherein the AlN layer and the AlGaN layer have the thicknesses of 200nm and 600nm respectively; then, the atmosphere is changed to 200torr pressure, and gallium nitride growth conditions are carried out at 950 ℃, a 500nm heavily Mg-doped polar surface conversion layer is grown on the surface of the multi-layer buffer layer, and the concentration of Mg doped in the layer is 2E20/cm³(ii) a Then, changing the atmosphere to 70torr of pressure and under the growth condition of gallium nitride at 1000 ℃, growing a 3000nm internal carbon-doped high-resistance gallium nitride pressure-resistant thin film layer on the surface of the polar face conversion layer; then, changing the conditions to AlGaN growth conditions of 100torr pressure and 1030 ℃, and growing a 25% Al component AlGaN barrier layer with the thickness of 20nm on the surface of the pressure-resistant film layer; finally, the conditions are changed to 200torr pressure and 1050 ℃ temperature, a 300nm GaN channel layer grows on the surface of the barrier layer at the speed of 2 mu m/h, and the growth of the epitaxial structure is finished.

Example two:

first, a (111) -oriented silicon substrate having a diameter of 200mm was placed in an MOCVD reaction chamber, and high-temperature H was performed at a pressure of 70torr and a temperature of 1050 deg.C₂Processing, removing surface oxide; then, a 1000nm AlN/AlGaN multilayer buffer layer grows on the surface of the silicon substrate under the pressure of 70torr and the temperature of 1000 ℃, wherein the AlN layer and the AlGaN layer are respectively 300nm and 700nm thick; then, changing the atmosphere to 200torr pressure and 950 ℃ gallium nitride growth condition, growing a 200nm heavily Mg-doped polar surface conversion layer on the surface of the multi-layer buffer layer, wherein the Mg doping concentration is 5E20/cm³(ii) a Then, ethane is introduced under the conditions of changing the atmosphere to 100torr pressure and 1050 ℃, and a 3000nm carbon-doped high-resistance gallium nitride pressure-resistant thin film layer grows; then, changing the conditions to AlGaN growth conditions of 100torr pressure and 1030 ℃, and growing a 25% Al component AlGaN barrier layer with the thickness of 20nm on the surface of the pressure-resistant film layer; then, changing the conditions to 200torr, 1050℃ and 1050 ℃ temperature, and growing a 300nm GaN channel layer on the surface of the barrier layer at the speed of 2 mu m/h; finally, growing a first crystal on the surface of the channel layer under the pressure of 70torr and the temperature of 1000 DEG CAnd (4) finishing the growth of the epitaxial structure by a cap layer of AlGaN with the layer of 50 nm.

It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.