Fabrication of microparabolic reflector for infrared antenna coupled detectors

Abstract

The fabrication process of a microparabolic reflector using isotropic xenon difluoride XeF 2 etching technique is presented and analysed through this work for developing infrared antenna-coupled detectors. Although many parametric studies described the behaviour of this process in the literature, the non-linearity of the process and its dramatic dependency on the pattern definition result in great difficulties when adopting the process for developing a particular structure. The main focus of this work is, therefore, to present a detailed etching analysis as dictated in the proposed design providing the proper etching recipe according to the proposed structure design and its associated masking pattern. Deep insights into the process have been highlighted suggesting the necessity of the process assessment in terms of evaluating the threedimensional etched volume rather than the etched depth. This will potentially solve the non-linearity behaviour and the pattern dependency problem. The optimum etching recipe yields approximately a total volume of 0.354 mm 3 through the proper patterning mask. The resultant parabolic cavities have 75 and 13 mm in their diameter and depth, respectively, as required for the proposed structure. The integration of a microparabolic reflector with such detectors will potentially enhance the specific detectivity of these detectors.

Cavity-Backed Antenna-Coupled Nanothermocouples

“…Note that the structure of our antenna configuration is very similar to a spherical reflector IR antenna 35,36 ; however, the distance between the feed antenna (primary and secondary antennas) and the spherical reflector (cavity wall) is less than 2λ. Thus, the reflector is in the near-field of the feed antenna, and as a result our sensor size is about five times smaller.…”

Thermoelectrically Coupled Nanoantennas for Solar Research

“…1c, the device response increases by about 100 times [14]. Besides thermal insulation, the cavity also acts as an optical element and focuses the incident IR radiation toward the antenna [14,15]. For a spherical cavity, and within the paraxial approximation model, the focal point is f=D/4, where D is the aperture size of the cavity.…”

Nano-Antenna Coupled Infrared Detector Design

“…Another technique that can substantially reduce surface wave degradation is by using either a circular or rectangular shaped integrating cavity, at the back of the substrate [ 55 ]. In this context, the parabolic reflector integrated structure has been proposed as illustrated in Figure 9 [ 57 ]. Besides reducing the substrate mode losses, that structure also offers high polarization discrimination response and increased effective antenna aperture area that adds a space diversity gain to the detector and inherently increases its detectivity [ 58 ].…”

“… Parabolic reflector cavity backed structure: ( a ) Demonstrative diagram ( b ) Scanning electron micrograph (SEM) of a complete integrated device [ 57 ]. …”