Lithography-free microfabrication of AlGaN/GaN 2DEG strain sensors using laser ablation and direct wire bonding

Abstract

This work presents a simple and rapid lithography-free (i.e., maskless) microfabrication process for strain-sensitive aluminum gallium nitride (AlGaN)/GaN sensors. We microfabricated an AlGaN/GaN strain sensor through laser ablation of the underlying Si (111) substrate and direct bonding of aluminum wires to the AlGaN surface, creating a Schottky contact to the twodimensional electron gas (2DEG). We measured the sensor's current-voltage operation while displacing the center of the membrane up to 106.7 μm and characterized its sensitivity at from 0.5 to 2 V bias (i.e., 5 to 100 nA/μm). This work advances the development of AlGaN/GaN-on-Si microelectronics (e.g., pressure sensors, accelerometers, and gyroscopes) using the simplified fabrication process, which eliminates lithography, metallization, and etching, and reduces the manufacturing time (5 min) and cost, as well as the need for cleanroom environments.

Characterization of the piezoresistance in highly doped p-type 3C-SiC at cryogenic temperatures

“…This high etching rate allows quick prototyping of pressure sensors. 25 In addition, the use of laser engraving eliminates the requirement for the hard-mask used in backside-Si-etching, which significantly simplifies our fabrication process (see the ESI † ). Subsequently, the as-fabricated pressure sensor was mounted on a home-built PCB board to form an enclosed chamber under the SiC/Si membrane.…”

Highly sensitive pressure sensors employing 3C-SiC nanowires fabricated on a free standing structure

“…Finally, the Si membrane was formed by etching the Si substrates from the backside. For simplicity, a large scale Si membrane with dimension of 5 mm × 5 mm × 150 µm was fabricated using a UV laser with an etching rate of 60 µm/min [28]. For comparison, a free-standing micro SiC resistor on Si-membrane pressure sensor was also fabricated.…”