RU204372U1 - Heterostructure field-effect transistor based on semiconductor gallium nitride compound - Google Patents

Abstract

The utility model relates to the technology of microelectronics, namely to the technology of obtaining discrete devices and monolithic integrated circuits based on a semiconductor compound of gallium nitride, in particular, to the creation of ohmic and barrier contacts for heterostructure field-effect transistors with high electron mobility. In the transistor, the ohmic contact is made on the basis of a three-layer Ta / Al / Pd metallization. The Ta layer with a thickness of 5-100 nm is located on the surface of the semiconductor wafer, on its surface there is an Al layer with a thickness of 50-1000 nm, on the surface of which there is a Pd layer with a thickness of 5-100 nm. The T-shaped gate is made on the basis of a three-layer composition in which a barrier-forming layer of Ni with a thickness of 10-200 nm is located in series on the surface of a semiconductor wafer, a conductive layer based on Al with a thickness of 10-1000 nm, a protective layer based on Pd with a thickness of 10-200 nm ... The technical result is an increase in the thermal stability of electrical parameters. 1 ill.

Description

The utility model relates to the technology of microelectronics, namely to the technology of obtaining discrete devices and monolithic integrated circuits based on a semiconductor compound of gallium nitride, in particular, to the creation of ohmic and barrier contacts for heterostructure field-effect transistors with high electron mobility.

Known field-effect transistor (Wei-Chou Wang, Chia-Hao Chen, Jhih-Han Du, Ming-Hung Weng, Che-Kai Lin, Chieh-Chih Huang, Chien-Chih Chang, Shih-Hui Huang, Yi-Feng Wei, Yao -Chung Hsieh, Michael Casbon, Paul J. Tasker, Wen-Kai Wang, I-Te Cho, Walter Wohlmuth. Development and Control of a 0.25 μm Gate Process Module for AlGaN / GaN HEMT Production // CS MANTECH Conference, May 13th - 16th, 2013, New Orleans, Louisiana, USA. PP. 143-146), in which ohmic contacts are made on the basis of a multilayer composition Ti / Al / Ni / Au and T-shaped gates 0.25 μm long based on two-layer Ni / Au.

The disadvantage of this transistor is the high cost of metallization of ohmic contacts and a T-shaped gate associated with the use of thick Au layers.

Known designs of Schottky field-effect transistor gates (Ting-En Hsieh Yueh-Chin Lin Yueh-Chin Lin Fang-Ming Li Edward Yi-Chang / GaN High-Electron-Mobility Transistor with WNx / Cu Gate for High-Power Applications // Journal of Electronic Materials 44 (12), 2015; Yueh-Chin Lin, Chih-Hsiang Chang, Fang-Ming Li, Li-Han Hsu, and Edward Yi Chang. Evaluation of TiN / Cu Gate Metal Scheme for AlGaN / GaN High-Electron-Mobility Transistor Application // Applied Physics Express 6 (2013) 091003)), in which the gate metallization is made on the basis of a completely brackless two-layer metallization, where a barrier-forming layer based on thin films of nitrides of refractory metals WNx or TiN is located on the surface of the semiconductor wafer, and the conductive layer on based on Cu is located on the surface of the barrier-forming layer.

The disadvantages of this transistor is the impossibility of forming a barrier forming layer based on films of nitrides of refractory metals by methods of direct optical or electron-beam lithography, which significantly reduces the practical value of these gate designs.

The closest to the claimed utility model in terms of the largest number of essential features is a transistor based on a gallium nitride semiconductor compound (Yuen-Yee Wong, Yu-Kong Chen, Jer-Shen Maa, Hung-Wei Yu, Yung-Yi Tu, Chang-Fu Dee, Chi-Chin Yap, and Edward Yi Chang. Low resistance copper-based ohmic contact for AlGaN / GaN high electron mobility transistors // Appl. Phys. Lett. 103, 152104 (2013). The device is a heterostructure field-effect transistor with high electron mobility, in which ohmic contacts are made on the basis of four-layer Ti / Al / Ni / Cu metallization, where the Ti layer is located on the surface of the semiconductor wafer and has a thickness 20 nm, the Al layer is located on the surface of the Ti layer and has a thickness of 120 nm, the Ni layer is located on the surface of the Al layer and has a thickness of 25 nm, and the Cu layer is located on the surface of the Ni layer and has a thickness of 50 nm.

The disadvantages of this transistor is the low thermal stability of the electrical parameters of the ohmic contact, due to the penetration of rapidly diffusing copper atoms into GaN at an elevated temperature.

The objective of this utility model is to increase the thermal stability of the electrical parameters of both an ohmic contact and a T-shaped gate of a heterostructure field-effect transistor based on a gallium nitride semiconductor compound.

The technical problem posed in this utility model is solved due to the fact that a transistor based on a gallium nitride semiconductor compound is made of a semiconductor wafer with buffer, channel and barrier layers, which includes ohmic source and drain contacts and a T-shaped gate. The ohmic contact is made on the basis of a three-layer metallization of Ta / Al / Pd, while a Ta layer with a thickness of 5-100 nm on the surface of a semiconductor wafer, an Al layer with a thickness of 50-1000 nm is located on the surface of the Ta layer, a Pd layer with a thickness of 5-100 nm is located on the surface of the layer Al. The T-shaped gate is made on the basis of a three-layer composition consisting of a barrier-forming layer of Ni with a thickness of 10-200 nm located on the surface of a semiconductor wafer, a conductive layer based on Al with a thickness of 10-1000 nm, located on the surface of a barrier-forming layer, and a protective layer based on Pd with a thickness 10-200 nm located on the surface of the conductive Al layer.

The essence of the present invention is illustrated by an illustration, which shows the proposed device in section.

The figure shows the following structural elements of the device:

1 - semiconductor substrate

2 - mesa isolation

3 - epitaxial heterostructure

3a - buffer layer

3b - channel layer

3c - barrier layer

4, 5 - ohmic contacts to the drain and source regions

4a, 5a - barrier-forming layer

4b, 5b - conductive layer

4c, 5c - protective layer

6 - T-shaped shutter

6a - barrier-forming layer

6b - conductive layer

6с - protective layer

The device is a heterostructure field-effect transistor with a high electron mobility based on a semiconductor compound of gallium nitride, which consists of a substrate 1, in which the transistor locations are separated by mesa insulation 2, an epitaxial heterostructure 3 including a buffer layer 3a, channel layer 3b, and a barrier layer 3c , ohmic contact of source 4 and drain 5, made on the basis of three-layer metallization Ta / Al / Pd //. The Ta layer is located on the surface of the semiconductor wafer and has a thickness of 5-100 nm, the Al layer is located on the surface of the Ta layer and has a thickness of 50-1000 nm, the Pd layer is located on the surface of the Al layer and has a thickness of 5-100 nm. T-shaped gate 6 is made on the basis of a three-layer composition and consisting of a barrier-forming layer 6a based on Ni with a thickness of 10-200 nm, located on the surface of a semiconductor wafer, a conductive layer 6b based on Al with a thickness of 10-1000 nm, located on the surface of a layer of a barrier-forming layer 6a and a Pd-based protective layer 6c with a thickness of 10-200 nm disposed on the surface of the Al conductive layer.

The technical result is provided by the fact that the Al film is used as a conductor in the composition of the metallization of the ohmic contact and the T-shaped gate, as well as the protective layer is made on the basis of the film, which makes it possible to significantly increase the thermal stability of the electrical parameters of the ohmic and barrier contacts, and, as a result, to increase reliability characteristics of the transistor.

In addition, the proposed solution makes it possible to reduce the cost of its manufacture, since there is no gold in the metallization of the ohmic contact and the T-shaped gate of the transistor.

The proposed utility model can be used in devices in the design of 5G networks.

Claims (1)

A transistor based on a semiconductor compound of gallium nitride, made of a semiconductor plate with a buffer, channel and barrier layers, including ohmic contacts of the source and drain and a T-shaped gate, characterized in that the ohmic contact is made on the basis of three-layer metallization Ta / Al / Pd, while a Ta layer with a thickness of 5-100 nm on the surface of a semiconductor wafer, an Al layer with a thickness of 50-1000 nm is located on the surface of the Ta layer, a Pd layer with a thickness of 5-100 nm is located on the surface of the Al layer, the T-shaped gate is based on a three-layer a composition consisting of a barrier-forming Ni layer 10-200 nm thick located on the surface of a semiconductor wafer, a conductive Al-based layer 10-1000 nm thick located on the surface of the barrier-forming layer, and a Pd-based protective layer 10-200 nm thick located on surface of the Al conductive layer.

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