# Toward Industrial Exploitation of THz Frequencies: Integration of SiGe MMICs in Silicon-Micromachined Waveguide Systems Journal article, 2019

A new integration concept for terahertz (THz) systems is presented in this article, wherein patterned silicon-on-insulator wafers form all DC, IF, and RF networks in a homogeneous medium, in contrast to existing solutions. Using this concept, silicon-micromachined waveguides are combined with silicon germanium (SiGe) monolithic microwave integrated circuits (MMICs) for the first time. All features of the integration platform lie in the waveguide's H-plane. Heterogeneous integration of SiGe chips is achieved using a novel in-line H-plane transition. As an initial step toward complete systems, we outline the design, fabrication, and assembly of back-to-back transition structures, for use at D -band frequencies (110–170 GHz). Special focus is given to the industrial compatibility of all components, fabrication, and assembly processes, with an eye on the future commercialization of THz systems. Prototype devices are assembled via two distinct processes, one of which utilizes semiautomated die-bonding tools. Positional and orientation tolerances for each process are quantified. An accuracy of $\pm \text{3.5}\; \mu \text{m}$ , $\pm \text{1.5} ^\circ$ is achieved. Measured $S$ -parameters for each device are presented. The insertion loss of a single-ended transition, largely due to MMIC substrate losses, is 4.2–5.5 dB, with a bandwidth of 25 GHz (135–160 GHz). Return loss is in excess of 5 dB. Measurements confirm the excellent repeatability of the fabrication and assembly processes and, thus, their suitability for use in high-volume applications. The proposed integration concept is highly scalable, permitting its usage far into the THz frequency spectrum. This article represents the first stage in the shift to highly compact, low-cost, volume-manufacturable THz waveguide systems.

## Author

### James Campion

Royal Institute of Technology (KTH)

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

### Zhongxia Simon He

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

### Bernhard Beuerle

Royal Institute of Technology (KTH)

Royal Institute of Technology (KTH)

### Umer Shah

Royal Institute of Technology (KTH)

Ericsson

Ericsson

Ericsson

Ericsson

### Herbert Zirath

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

### Joachim Oberhammer

Royal Institute of Technology (KTH)

2156-342X (ISSN)

Vol. 9 6 624-636

### Micromachined terahertz systems -a new heterogeneous integration platform enabling the commercialization of the THz frequency spectrum (M3TERA)

European Commission (Horizon 2020), 2015-02-01 -- 2017-12-31.

### Subject Categories

Other Engineering and Technologies not elsewhere specified

Other Electrical Engineering, Electronic Engineering, Information Engineering

### DOI

10.1109/TTHZ.2019.2943572