Enhancement-Mode High Electron Mobility Transistors Lattice-Matched to InP Substrates Utilizing Ti/Pt/Au Metallization

Copper-metallized AlGaAs/InGaAs pseudomophic high-electron mobility transistor single-pole-double-throw (SPDT) switches utilizing platinum (Pt, 70 nm) as the diffusion barrier have been studied and demonstrated. As compared with the Au-metallized switches, the Cu-metallized SPDT switches exhibited comparable performance with insertion loss less than 0.5 dB, return loss larger than 20 dB, isolation larger than 35 dB, and the input power for 1-dB compression (input P 1 dB ) of 28.3 dBm at 2.5 GHz. In order to evaluate the temperaturedependent impact on dc and RF characteristics of the coppermetallized switches for high-temperature applications, the switches have been tested at different temperatures. The device exhibits low thermal threshold coefficients (δV th /δT ) of −0.25 mV/K from 300 K to 500 K, good microwave performance at 380 K with insertion loss less than 0.5 dB, isolation higher than 40 dB, and the input power for 1-dB compression (input P 1 dB ) of 28.45 dBm at 2.5 GHz. To test the thermal stability of the Pt diffusion barrier, these switches were annealed at 250 • C for 20 h. After the annealing, the switches showed no degradation of the dc characteristics. In addition, after a high temperature storage life environment test at 150 • C, these copper-metallized switches remained capable of excellent power handling. To test the operation reliability of the copper-metallized switches, the copper-metallized switches were subjected to ON/OFF (control voltage = +3/0 V exchange) stress test for 24 h at room temperature. The devices maintained excellent RF characteristics after the stress test. Consequently, it is successfully demonstrated through these tests that copper metallization using Pt as the diffusion barrier could be applied to the GaAs monolithic microwave integrated circuit switch fabrication with good RF performance, high-temperature characteristics, and reliability.Index Terms-Copper metallization, platinum, pseudomophic high-electron mobility transistor (PHEMT), single-pole-doublethrow (SPDT), switch, temperature.

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“…10 shows that the V th decreases with increasing temperature. The V th of a δ-doped HEMT can be obtained by solving (1) as follows [13], [15]:…”

Section: Resultsmentioning

confidence: 99%

Evaluation of Electrical Characteristics of the Copper Metallized SPDT GaAs Switches at Elevated Temperatures

Chang

Lin

et al. 2009

IEEE Trans. Device Mater. Relib.

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show abstract

“…10 shows that the V th decreases with increasing temperature. The V th of a δ-doped HEMT can be obtained by solving 1as follows [13], [15]:…”

Section: Resultsmentioning

confidence: 99%

Evaluation of Electrical Characteristics of the Copper-Metallized SPDT GaAs Switches at Elevated Temperatures

Chang

Lin

et al. 2008

IEEE Trans. Device Mater. Relib.

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Copper-metallized AlGaAs/InGaAs pseudomophic high-electron mobility transistor single-pole-double-throw (SPDT) switches utilizing platinum (Pt, 70 nm) as the diffusion barrier have been studied and demonstrated. As compared with the Au-metallized switches, the Cu-metallized SPDT switches exhibited comparable performance with insertion loss less than 0.5 dB, return loss larger than 20 dB, isolation larger than 35 dB, and the input power for 1-dB compression (input P 1 dB) of 28.3 dBm at 2.5 GHz. In order to evaluate the temperaturedependent impact on dc and RF characteristics of the coppermetallized switches for high-temperature applications, the switches have been tested at different temperatures. The device exhibits low thermal threshold coefficients (δV th /δT) of −0.25 mV/K from 300 K to 500 K, good microwave performance at 380 K with insertion loss less than 0.5 dB, isolation higher than 40 dB, and the input power for 1-dB compression (input P 1 dB) of 28.45 dBm at 2.5 GHz. To test the thermal stability of the Pt diffusion barrier, these switches were annealed at 250 • C for 20 h. After the annealing, the switches showed no degradation of the dc characteristics. In addition, after a high temperature storage life environment test at 150 • C, these copper-metallized switches remained capable of excellent power handling. To test the operation reliability of the copper-metallized switches, the copper-metallized switches were subjected to ON/OFF (control voltage = +3/0 V exchange) stress test for 24 h at room temperature. The devices maintained excellent RF characteristics after the stress test. Consequently, it is successfully demonstrated through these tests that copper metallization using Pt as the diffusion barrier could be applied to the GaAs monolithic microwave integrated circuit switch fabrication with good RF performance, high-temperature characteristics, and reliability.

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“…Compared with device B, device A has a high V th , which can be attributed to the higher ratio of Pt/Ti in Schottky contact metal, which increases the φ b of Ti-based Schottky junction because the Pt-based Schottky junction has a higher φ b than the Ti-based Schottky junction. [18] Besides, the smaller d of device A caused by "Pt sinking" can also increase the V th and g m max . [19][20][21][22] Therefore, the formation of Pt distribution in Schottky contact metal can be explained as being due to the middle metal layer Pt spreading into the gate recess during the gate metal evaporation, which not only expands the gate length but also increases the Ti-based Schottky barrier height.…”

Section: Characteristicsmentioning

confidence: 99%

Influences of increasing gate stem height on DC and RF performances of InAlAs/InGaAs InP-based HEMTs*

Tong

Ding

et al. 2021

Chinese Phys. B

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The T-gate stem height of InAlAs/InGaAs InP-based high electron mobility transistor (HEMT) is increased from 165 nm to 250 nm. The influences of increasing the gate stem height on the direct current (DC) and radio frequency (RF) performances of device are investigated. A 120-nm-long gate, 250-nm-high gate stem device exhibits a higher threshold voltage (V th) of 60 mV than a 120-nm-long gate devices with a short gate stem, caused by more Pt distributions on the gate foot edges of the high Ti/Pt/Au gate. The Pt distribution in Schottky contact metal is found to increase with the gate stem height or the gate length increasing, and thus enhancing the Schottky barrier height and expanding the gate length, which can be due to the increased internal tensile stress of Pt. The more Pt distributions for the high gate stem device also lead to more obvious Pt sinking, which reduces the distance between the gate and the InGaAs channel so that the transconductance (g m) of the high gate stem device is 70 mS/mm larger than that of the short stem device. As for the RF performances, the gate extrinsic parasitic capacitance decreases and the intrinsic transconductance increases after the gate stem height has been increased, so the RF performances of device are obviously improved. The high gate stem device yields a maximum f t of 270 GHz and f max of 460 GHz, while the short gate stem device has a maximum f t of 240 GHz and the f max of 370 GHz.

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Enhancement-Mode High Electron Mobility Transistors Lattice-Matched to InP Substrates Utilizing Ti/Pt/Au Metallization

Cited by 4 publications

References 12 publications

Evaluation of Electrical Characteristics of the Copper Metallized SPDT GaAs Switches at Elevated Temperatures

Evaluation of Electrical Characteristics of the Copper Metallized SPDT GaAs Switches at Elevated Temperatures

Evaluation of Electrical Characteristics of the Copper-Metallized SPDT GaAs Switches at Elevated Temperatures

Influences of increasing gate stem height on DC and RF performances of InAlAs/InGaAs InP-based HEMTs*

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