阅读说明：本技术 毫米波开关芯片 (Millimeter wave switch chip ) 是由 王俊龙 陈海森 于 2021-09-16 设计创作，主要内容包括：本发明公开了一种毫米波开关芯片,SiC衬底的上表面形成有AlN缓冲层,所述AlN缓冲层的上表面形成有第一GaN层,通过背栅槽使得部分第一GaN层的下表面露出,所述第一GaN层的下表面的裸露部分形成有背栅；所述第一GaN层上表面的左侧形成有源极欧姆接触层,所述第一GaN层上表面的右侧形成有漏极欧姆接触层,所述源极欧姆接触层与所述漏极欧姆接触层之间的第一GaN层的上表面从下到上形成有第一AlGaN层、第二GaN层以及第二AlGaN层,所述源极欧姆接触层的上表面形成有源极,所述漏极欧姆接触层的上表面形成有漏极,所述第二AlGaN层的上表面形成有顶栅。所述芯片具有开关频率速度高等优点。(The invention discloses a millimeter wave switch chip.A AlN buffer layer is formed on the upper surface of a SiC substrate, a first GaN layer is formed on the upper surface of the AlN buffer layer, the lower surface of part of the first GaN layer is exposed through a back gate groove, and a back gate is formed on the exposed part of the lower surface of the first GaN layer; the left side on first GaN layer upper surface is formed with source ohmic contact layer, the right side on first GaN layer upper surface is formed with drain electrode ohmic contact layer, source electrode ohmic contact layer with the upper surface from the bottom up on the first GaN layer between the drain electrode ohmic contact layer is formed with first AlGaN layer, second GaN layer and second AlGaN layer, the upper surface on source electrode ohmic contact layer is formed with the source electrode, the upper surface on drain electrode ohmic contact layer is formed with the drain electrode, the upper surface on second AlGaN layer is formed with the top bars. The chip has the advantages of high switching frequency speed and the like.)

1. A millimeter wave switch chip which is characterized in that: the silicon-based GaN-based chip comprises a SiC substrate (1), wherein an AlN buffer layer (2) is formed on the upper surface of the SiC substrate (1), a first GaN layer (3) is formed on the upper surface of the AlN buffer layer (2), a back gate groove is formed at the bottom of the chip, part of the lower surface of the first GaN layer (3) is exposed through the back gate groove, and a back gate (4) is formed on the exposed part of the lower surface of the first GaN layer (3); the left side of first GaN layer (3) upper surface is formed with source ohmic contact layer (5), the right side of first GaN layer (3) upper surface is formed with drain electrode ohmic contact layer (6), source electrode ohmic contact layer (5) with the upper surface from the bottom up of first GaN layer (3) between drain electrode ohmic contact layer (6) is formed with first AlGaN layer (7), second GaN layer (8) and second AlGaN layer (9), the upper surface of source electrode ohmic contact layer (5) is formed with source electrode (10), the upper surface of drain electrode ohmic contact layer (6) is formed with drain electrode (11), the upper surface of second AlGaN layer (9) is formed with top gate (12).

2. The millimeter wave switch chip of claim 1, wherein: the back gate (4) is not in contact with the SiC substrate (1) and the AlN buffer layer (2).

3. The millimeter wave switch chip of claim 1, wherein: the upper surfaces of the source electrode ohmic contact layer (5), the drain electrode ohmic contact layer (6) and the second AlGaN layer (9) are on the same horizontal plane.

4. The millimeter wave switch chip of claim 1, wherein: the area of the source electrode (10) is the same as that of the source electrode ohmic contact layer (5), the area of the drain electrode (11) is the same as that of the drain electrode ohmic contact layer (6), and the area of the top gate (12) is smaller than that of the second AlGaN layer (9).

5. The millimeter wave switch chip of claim 1, wherein: the thickness of the back gate (4) is smaller than the sum of the thicknesses of the SiC substrate (1) and the AlN buffer layer (2).

6. The millimeter wave switch chip of claim 1, wherein: the thickness of the SiC substrate (1) is 25-50 microns.

7. The millimeter wave switch chip of claim 1, wherein: the AlN buffer layer (2) has a thickness of 10nm to 50 nm.

8. The millimeter wave switch chip of claim 1, wherein: the first and second GaN layers have a thickness of 10nm to 50nm, and the first and second AlGaN layers have a thickness of 15nm to 100nm, in which the Al component is 30%.

9. The millimeter wave switch chip of claim 1, wherein: the source electrode ohmic contact layer (5) and the drain electrode ohmic contact layer (6) are made of Ti, Al, Ni and/or Au.

10. The millimeter wave switch chip of claim 1, wherein: the top gate (12) and the back gate (4) are Schottky contact electrodes, and the manufacturing materials of the Schottky contact electrodes are Ti, Pt and/or Au.

Technical Field

The invention relates to the technical field of millimeter wave switch devices, in particular to a millimeter wave switch chip with high switching frequency and high switching speed.

Background

The millimeter wave is electromagnetic wave with the frequency within the range of 30GHz-300GHz, and the millimeter wave switch plays a role in starting and stopping millimeter wave signal transmission in a millimeter wave frequency band. Some switches of the millimeter wave frequency band are manufactured based on PIN junctions at present, but the millimeter wave switch chip based on the technology is difficult to be used for space transmission. In the millimeter wave frequency band, a GaN HEMT (high electron mobility transistor) has high electron mobility and high speed due to the presence of two-dimensional electron gas, and can effectively work in the millimeter wave frequency band. The GaN-based HEMT structure is expected to realize a switch chip with millimeter wave transmission in the transverse direction and in the longitudinal space.

Disclosure of Invention

The invention aims to solve the technical problem of how to provide a millimeter wave switch chip with high switching frequency and high speed.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a millimeter wave switch chip which is characterized in that: the silicon-based chip comprises a SiC substrate, wherein an AlN buffer layer is formed on the upper surface of the SiC substrate, a first GaN layer is formed on the upper surface of the AlN buffer layer, a back gate groove is formed at the bottom of the chip, part of the lower surface of the first GaN layer is exposed through the back gate groove, and a back gate is formed on the exposed part of the lower surface of the first GaN layer; the left side on first GaN layer upper surface is formed with source ohmic contact layer, the right side on first GaN layer upper surface is formed with drain electrode ohmic contact layer, source electrode ohmic contact layer with the upper surface from the bottom up on the first GaN layer between the drain electrode ohmic contact layer is formed with first AlGaN layer, second GaN layer and second AlGaN layer, the upper surface on source electrode ohmic contact layer is formed with the source electrode, the upper surface on drain electrode ohmic contact layer is formed with the drain electrode, the upper surface on second AlGaN layer is formed with the top bars.

The further technical scheme is as follows: the back gate is not in contact with the SiC substrate and the AlN buffer layer.

The further technical scheme is as follows: the upper surfaces of the source electrode ohmic contact layer, the drain electrode ohmic contact layer and the second AlGaN layer are on the same horizontal plane.

The further technical scheme is as follows: the area of the source electrode is the same as that of the source electrode ohmic contact layer, the area of the drain electrode ohmic contact layer is the same as that of the drain electrode ohmic contact layer, and the area of the top gate is smaller than that of the second AlGaN layer.

The further technical scheme is as follows: the thickness of the back gate is smaller than the sum of the thicknesses of the SiC substrate and the AlN buffer layer.

Preferably, the thickness of the SiC substrate is 25 micrometers to 50 micrometers.

Preferably, the AlN buffer layer has a thickness of 10nm to 50 nm.

Preferably, the first and second GaN layers have a thickness of 10nm to 50nm, the first and second AlGaN layers have a thickness of 15nm to 100nm, and the Al composition is 30%.

Preferably, the source ohmic contact layer and the drain ohmic contact layer are made of Ti, Al, Ni and/or Au.

Preferably, the top gate and the back gate are schottky contact electrodes, and the material for making the top gate and the back gate is Ti, Pt and/or Au.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: the switch chip is manufactured based on a GaN HEMT device structure, adopts a GaN/AlGaN material structure, adopts a double HEMT communication structure to manufacture a switch device, and adopts a top gate and back gate double-gate structure to increase the control of two-dimensional electron gas. The switching effect on the millimeter wave transverse structure (in the gate length direction) can be realized, and the switching effect on the millimeter wave in the longitudinal space (perpendicular to the gate length direction) can be realized. Due to the adoption of the double HEMT channel structure, the switching function of high-power millimeter wave signals can be realized. Based on the millimeter wave switch chip that this application provided, the switch insertion loss is less than 3dB, and the bearable power is greater than 5W, as space millimeter wave switch, can be applied to whole millimeter wave frequency channel, and its switching frequency speed is high, can reach 1 GHz.

Drawings

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

Fig. 1 is a schematic structural diagram of a switch chip according to an embodiment of the present invention;

wherein: 1. a SiC substrate; 2. an AlN buffer layer; 3. a first GaN layer; 4. a back gate; 5. a source ohmic contact layer; 6. a drain ohmic contact layer; 7. a first AlGaN layer; 8. a second GaN layer; 9. a second AlGaN layer; 10. a source electrode; 11. a drain electrode; 12. and (6) top grid.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

As shown in fig. 1, the embodiment of the invention discloses a millimeter wave switch chip, which comprises a SiC substrate 1, wherein an AlN buffer layer 2 is formed on the upper surface of the SiC substrate 1, and a first GaN layer 3 is formed on the upper surface of the AlN buffer layer 2; a back gate groove is formed at the bottom of the chip, part of the lower surface of the first GaN layer 3 is exposed through the back gate groove, a back gate 4 is formed at the exposed part of the lower surface of the first GaN layer 3, the back gate 4 is not in contact with the SiC substrate 1 and the AlN buffer layer 2, and the thickness of the back gate 4 is smaller than the sum of the thicknesses of the SiC substrate 1 and the AlN buffer layer 2, namely, the back gate 4 is not exposed from the back gate groove; the left side of 3 upper surfaces on first GaN layer is formed with source ohmic contact layer 5, the right side of 3 upper surfaces on first GaN layer is formed with drain electrode ohmic contact layer 6, the ohmic basal layer uses metal material to make, source electrode ohmic contact layer 5 with the upper surface from the bottom up of 3 on first GaN layer between drain electrode ohmic contact layer 6 is formed with first AlGaN layer 7, second GaN layer 8 and second AlGaN layer 9, the upper surface of source electrode ohmic contact layer 5 is formed with source electrode 10, the upper surface of drain electrode ohmic contact layer 6 is formed with drain electrode 11, the upper surface of second AlGaN layer 9 is formed with top bars 12.

Further, in the present application, as shown in fig. 1, the upper surfaces of the source ohmic contact layer 5, the drain ohmic contact layer 6 and the second AlGaN layer 9 are on the same horizontal plane, so that the chip has a better appearance. Further, the area of the source electrode 10 is the same as the area of the source ohmic contact layer 5 (the area refers to the area of the upper surface), the area of the drain electrode 11 is the same as the area of the drain ohmic contact layer 6, and the area of the top gate 12 is smaller than the area of the second AlGaN layer 9.

Preferably, the thickness of the SiC substrate 1 may be 25 micrometers to 50 micrometers; the AlN buffer layer 2 may have a thickness of 10nm to 50 nm; the first and second GaN layers may have a thickness of 10nm to 50nm, the first and second AlGaN layers may have a thickness of 15nm to 100nm, and the Al composition may be 30%; the source electrode ohmic contact layer 5 and the drain electrode ohmic contact layer 6 can be made of Ti, Al, Ni and/or Au; the top gate 12 and the back gate 4 are schottky contact electrodes, and the material for making the schottky contact electrodes may be Ti, Pt and/or Au. The thickness of the SiC substrate 1, the thickness of the AlN buffer layer 2, the thicknesses of the first and second GaN layers, and the thicknesses of the first and second AlGaN layers described in the present application may have other values, and the source ohmic contact layer 5 and the drain ohmic contact layer 6 may be made of other materials as long as the requirements of the chip described in the present application are satisfied.

In the application, the chip limits electrons generated by piezoelectric polarization between interfaces in a two-dimensional space due to the bending effect of an energy band between the AlGaN layer and the GaN layer, so that two-dimensional electron gas is formed, and millimeter waves are absorbed by using the concentration of the two-dimensional electron gas. Due to the adoption of the two layers of two-dimensional electron gas channels, when millimeter waves are transmitted from top to bottom, the millimeter waves need to be absorbed by the two layers of two-dimensional electron gas, and the concentration of the electron gas in the two-dimensional electron gas can be regulated and controlled by adjusting the voltages of the top gate 12 and the back gate 4. When the concentration of the two-dimensional electron gas is high, the energy of the millimeter wave signal is absorbed by the two-dimensional electron gas, and the millimeter wave signal is in the off state of the millimeter wave switch. When the two-dimensional electron gas is depleted by the top gate 12 and the back gate 4, only intrinsic absorption of the millimeter wave signal can occur through the switching device at this time, that is, the on state of the millimeter wave switch, and the insertion loss of the millimeter wave signal can be generated at this time.

The epitaxial structure of the chip can be obtained by means of MOCVD or MBE, and the manufacturing process of the source electrode, the drain electrode and the top gate is well-established. In the back gate in the scheme, the SiC layer and the AlN buffer layer on the back side need to be polished, a part of the SiC layer and a part of the AlN buffer layer need to be removed by a gas etching method, and then the back gate is manufactured on the back side of the first GaN layer.

In summary, the switch chip in the present application is manufactured based on a GaN HEMT device structure, and adopts a GaN/AlGaN material structure, and a dual HEMT communication structure to manufacture a switch device, and adopts a top gate and back gate dual-gate structure to increase control over two-dimensional electron gas. The switching effect on the millimeter wave transverse structure (in the gate length direction) can be realized, and the switching effect on the millimeter wave in the longitudinal space (perpendicular to the gate length direction) can be realized. Due to the adoption of the double HEMT channel structure, the switching function of high-power millimeter wave signals can be realized. Based on the millimeter wave switch chip that this application provided, the switch insertion loss is less than 3dB, and the bearable power is greater than 5W, as space millimeter wave switch, can be applied to whole millimeter wave frequency channel, and its switching frequency speed is high, can reach 1 GHz.