Silicon micromachined waveguide components at 0.75 to 1.1 THz

Reck, Theodore; Jung-Kubiak, Cecile; Leal-Sevillano, Carlos A.; Chattopadhyay, Goutam

doi:10.1109/irmmw-thz.2014.6956008

Cited by 14 publications

(3 citation statements)

References 5 publications

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“…At submillimeter/THz frequencies, very high-precision machining is required for the device fabrication [36], [39], [40]. Fabrication tolerances and sidewall slope significantly degrade the desired RF performance of the final devices [27], [28]. Many researchers suffered from these [16], [32], [41]- [43] and started to be aware of the gravity of these problems [42], [44].…”

Section: Effects Of Fabrication Tolerances On Filter Performancementioning

confidence: 99%

Silicon Micromachined D-Band Diplexer Using Releasable Filling Structure Technique

Zhao

Glubokov

Campion

et al. 2020

IEEE Trans. Microwave Theory Techn.

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A D-band waveguide diplexer, implemented by silicon micromachining using releasable filling structure (RFS) technique to obtain high-precision geometries, is presented here for the first time. Prototype devices using this RFS technique are compared with devices using the conventional microfabrication process. The RFS technique allows etching large waveguide structures with nearly 90 • sidewall angles for the 400-µm-tall waveguides. The diplexer consists of two direct-coupled cavity six-pole bandpass filters, with the lower and the upper band at 130-134 and 141-148.5 GHz, respectively. The measured insertion loss of the two bands is 1.2 and 0.8 dB, respectively, and the measured return loss is 20 and 18 dB, respectively, across 85% of the passbands. The worst case adjacent channel rejection is better than 59 dB. The unloaded quality factors of a single cavity resonator are estimated from the measurements to reach 1400. Furthermore, for the RFS-based micromachined diplexer, an excellent agreement between measured and simulated data was observed, with a center frequency shift of only 0.8% and a bandwidth deviation of only 8%. In contrast to that, for the conventionally micromachined diplexer of this high complexity, the filter poles are not well controllable, resulting in a large center frequency shift of 3.5%, a huge bandwidth expanding of over 60%, a poor return loss of 6 and 10 dB for the lower and the upper band, respectively, and an adjacent channel rejection of only 22 dB.

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Section: Effects Of Fabrication Tolerances On Filter Performancementioning

confidence: 99%

Silicon Micromachined D-Band Diplexer Using Releasable Filling Structure Technique

Zhao

Glubokov

Campion

et al. 2020

IEEE Trans. Microwave Theory Techn.

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“…After etching, the remaining SiO 2 mask was removed with hydrofluoric acid and the wafer was cleaned with an O 2 plasma for 1 hr at 1000 W. We also performed a short thermal oxidation and etching step to improve the etched surfaces' morphology and smoothness [37]. We grew a sacrificial layer of SiO 2 in an oxidation furnace at 1050 °C using water vapor for approximately 1 hr, which we then removed with the above recipe.…”

Section: B Antireflection Structure Fabricationmentioning

confidence: 99%

16:1 bandwidth two-layer antireflection structure for silicon matched to the 190–310 GHz atmospheric window

et al. 2018

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Although high-resistivity, low-loss silicon is an excellent material for THz transmission optics, its high refractive index necessitates antireflection treatment. We fabricated a wide-bandwidth, two-layer antireflection treatment by cutting subwavelength structures into the silicon surface using multi-depth deep reactive ion etching (DRIE). A wafer with this treatment on both sides has <−20 dB (<1%) reflectance over 187-317 GHz at 15°angle of incidence in TE polarization. We also demonstrated that bonding wafers introduces no reflection features above the −20 dB level (also in TE at 15°), reproducing previous work. Together these developments immediately enable construction of wide-bandwidth silicon vacuum windows and represent two important steps toward gradient-index silicon optics with integral broadband antireflection treatment.

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“…Micro-electromechanical systems (MEMS) technology offers significant advantages in fabricating waveguide devices, featuring small fabrication tolerances, good surface roughness, and the capacity for batch fabrication and self-packaging [14][15][16][17][18][19]. Previous efforts have successfully fabricated and studied micromachined filters with central frequencies between 90 GHz and 1 THz [16,[20][21][22][23][24][25][26]. While SU-8-based micromachining has demonstrated positive results [27,28], the process tolerances and thermal issues associated with the base material need a careful consideration.…”

Section: Introductionmentioning

confidence: 99%

Wafer-scale silicon microfabrication technology toward realization of low-cost sub-THz waveguide devices

Zhao,

Wu,

Liu

2024

J. Micromech. Microeng.

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This paper presents a wafer-scale silicon microfabrication technology for low-cost sub-terahertz (sub-THz) waveguide device applications. Based on the effective scheme, a WR-05 (110 - 170 GHz) straight rectangular waveguide and a WR-2.8 (260 - 400 GHz) rectangular waveguide bandpass filter are implemented as demonstrated examples. The silicon deep reactive ion etching (DRIE) process is employed to etch through the total thickness of the silicon wafer and form the main waveguide channels. Then, a low-temperature thermal compression process was used to bond the trough-etched wafer with the top and bottom metallised silicon wafers to form the closed waveguide structures without any precise alignment process. The fabricated waveguide has the benefit of low transmission loss (0.03-0.05 dB/mm) at the whole G band. Besides, to measure the fabricated devices and solve the measuring equipment standard waveguide difference, silicon micromachined waveguide transitions are explored and fabricated to match two different frequency-band modules for measuring the waveguide filters in the desired full frequency band, which also has a potential application for the different size waveguide conversion. The measured results agree well with the simulated ones. The measured 3dB bandwidth is 9.3%, with a central frequency of 343 GHz; the average insertion loss (IL) is about 1.6 dB in the pass band, including two extra straight waveguides of 8 mm length on input/output ends and two external waveguide-to-waveguide transitions. The proposed method provides a feasible and cost-effective solution for the mass production of high-performance waveguide devices and integrated systems in sub-THz frequency bands and beyond.

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Silicon micromachined waveguide components at 0.75 to 1.1 THz

Cited by 14 publications

References 5 publications

Silicon Micromachined D-Band Diplexer Using Releasable Filling Structure Technique

Silicon Micromachined D-Band Diplexer Using Releasable Filling Structure Technique

16:1 bandwidth two-layer antireflection structure for silicon matched to the 190–310 GHz atmospheric window

Wafer-scale silicon microfabrication technology toward realization of low-cost sub-THz waveguide devices

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