Novel Manufacturing Route for Scale Up Production of Terahertz Technology Devices

Abstract

The advances in the Terahertz (THz) technology drive the needs for the design and manufacture of waveguide devices that integrate complex three-dimensional (3D) miniaturized components with meso- and micro-scale functional features and structures. Typical dimensions of the waveguide functional structures are in the range from 200 μm to 50 μm and dimensions decrease with the increase in the operating frequency of the waveguide devices. Technological requirements that are critical for achieving the desired microwave filtering performance of the waveguides include geometrical accuracy, alignment between functional features and surface integrity. In this context, this paper presents a novel manufacturing route for the scaled-up production of THz components that integrate computer numerical control (CNC) milling and laser micromachining. A solution to overcome the resulting tapering of the laser-machined structures while achieving a high accuracy and surface integrity of the machined features is applied in this research. In addition, an approach for two-side processing of waveguide structures within one laser machining setup is described. The capabilities of the proposed manufacturing process chain are demonstrated on two THz waveguide components that are functionally tested to assess the effects of the achieved machining results on devices' performance. Experimental results show that the proposed process chain can address the manufacturing requirements of THz waveguide filters, in particular the process chain is capable of producing filters with geometrical accuracy better than 10 μm, side wall taper angle deviation of less than 1 deg from vertical (90 deg), waveguide cavities corner radius better than 15 μm, and surface roughness (Sa) better than 1.5 μm. The manufacturing efficiency demonstrated in this feasibility study also provides sufficient evidences to argue that the proposed multistage manufacturing technique is a very promising solution for the serial production of small to medium batches of THz waveguide components. Finally, analyses of the manufacturing capabilities of the proposed process chain and the photoresist-based technologies were performed to clearly demonstrate the advantages of the proposed process chain over current waveguide fabrication solutions.

Effects of Top-hat Laser Beam Processing and Scanning Strategies in Laser Micro-Structuring

“…Furthermore, there is a consistent trend for miniaturization of new and existing devices that drives the advances in laser micro-machining. Efforts to achieve high geometrical accuracy, especially to minimize the tapering effect on side walls of structures fabricated by laser micro-machining, was the focus of many investigations, and different approaches to address this issue were suggested by researchers [10][11][12][13][14]. The main difficulties with these solutions are either the high accuracy requirements for the movements of mechanical stages, or their low repeatability and also their applicability for only specific structures.…”

Two-Side Laser Processing Method for Producing High Aspect Ratio Microholes

“…The method is not limited to drilling only circular holes but can also be used for producing any structures, both through and blind, as high positional accuracy can be achieved in producing functional features from the two opposite sides of the workpiece [26]. Two-side holes' fabrication was reported only in two implementations and only one of them utilised laser processing.…”

Submillimeter‐wave waveguide filters fabricated by SU‐8 process and laser micromachining

“…optimisation of laser processing parameters and settings. More details about the laser machining process can be found from [5,44,45]. Fig.…”