20 nm Metamorphic HEMT technology for terahertz monolithic integrated circuits

Abstract

A metamorphic high electron mobility transistor (mHEMT) technology with 20 nm gate length for manufacturing of terahertz monolithic integrated circuits (TMICs) is presented. The passive elements include up to four interconnection metallization layers separated by low-k dielectrics (BCB), SiN and air which can be used to realize front side signal lines. Shielding the substrate from the electromagnetic field on the wafer front side eliminates the need of a costly back side process including wafer thinning, through substrate via etching and back side metallization. The semiconductor heterostructure of the mHEMT comprises a strained pure InAs channel with high electron mobility and high electron density for proper device scaling. The realized mHEMTs achieve a source resistance r S of 0.12 Ωmm which is required to minimize resistive losses in combination with an extrinsic maximum transconductance g m_max of 2850 mS/mm. Elaborated on wafer calibration procedures and optimized test transistor layouts were used to improve the precision of the S-parameter measurements up to a frequency of 450 GHz which than could be used for model extraction. The presented 20 nm mHEMT technology was employed for the design of a compact eight stage low-noise amplifier (LNA) using miniaturized microstrip lines on BCB. The measured small signal gain of the LNA exceeds 15 dB from 500 -635 GHz.Keywords-low-noise amplifier (LNA), metamorphic high electron mobility transistor (mHEMT), terahertz monolithic integrated circuit (TMIC).I.

Roadmap of Terahertz Imaging 2021

“…These technologies employ different types of heterojunctions of semiconductors, and the highest operation frequencies f max are achieved for InP-based HEMTs with InGaAs/InAs composite channel and sub-100 nm short gate lengths [75]. Since the first report of extrapolated f max of InGaAs/InAlAs/InP HEMT with 35 nm gate exceeding the 1 THz limit [76], similar parameters were achieved for a 20 nm metamorphic HEMT technology [77] and the f max of 1.3 THz for an extended drain-side recess structure in 75 nm gate InAlAs/InGaAs HEMTs [78]. Although currently available just in a few places worldwide, such technologies are starting to be named as Terahertz Monolithic Integrated Circuits (TMICs) and, by now, have proven to be able to produce efficient frequency multipliers for 500 GHz [79] or 670 GHz [80], mixers for 600 GHz [81], low noise amplifiers for 600 GHz band [82][83][84], and transmitters and receivers for 850 GHz [85] with the record report of achieved amplification up to 8 dB at 1 THz [86].…”

Towards MMIC-Based 300GHz Indoor Wireless Communication Systems

“…Due to the outstanding low noise characteristics and excellent high frequency performance of high indium content channel HEMTs [12], [13], they were the technology of choice for the implementation of the presented Rx and Tx MMICs. A metamorphic approach on 4 semi insulating substrates is used for the epitaxial growth of the In 0.8 Ga 0.2 As/InAlAs device heterostructure.…”

Effects of Self-Heating on ${f}_{\text{T}}$ and ${f}_{\text{max}}$ Performance of Graphene Field-Effect Transistors

“…Recently, graphene field-effect transistors (GFETs) with the state-of-the-art extrinsic transit frequency f T = 34 GHz and a maximum frequency of oscillation f max = 37 GHz at a gate length L g = 0.5 μm have been demonstrated [8]. These values of f T and f max are already comparable to those of the best reported Si MOSFETs, but still well below the III-V HEMTs [9]- [11] . It is well recognized that the development of GFETs, operating in the amplifying mode, i.e., with high f max , is challenging due to relatively high drain conductance [12].…”