Pressure Sensor Devices Featuring a Chemical Passivation Made of a Locally Synthesized Diamond Layer

Abstract

The rear side of a pressure sensor diaphragm is prepared with an additional diamond layer as protective coating against harsh media. The preparation sequence for the diamond coating is developed as a simple backend process, combining only two additional steps in the standard process. These are the local seeding of nanodiamond layer and the low‐temperature diamond growth at <300 °C in a linear antenna microwave plasma‐enhanced chemical vapor deposition reactor, where only at the nanodiamond seeded sites, a high‐quality diamond film was synthesized. The seeding resolution in the setup used was limited to ≈80 μm, but can be further reduced. In an industry‐typical assembly sequence the diamond coated pressure sensor devices are further equipped with a support wafer and mounted to a TO‐8 socket. Tests of such sensor systems indicate that the diamond layer does not hamper the stability of the device. This proofed method of postprocessing an only‐local and low‐temperature synthesis of a diamond layer on the wafer‐level opens‐ up possibilities for many other applications, since this approach is scalable and in general cost effective.

A Review of Carbon Nanotubes, Graphene and Nanodiamond Based Strain Sensor in Harsh Environments

“…In coating [104], a solution containing nanodiamonds is dispensed onto the substrate and then spun to achieve a uniform coating. In inkjet printing [105], nanodiamonds are dispersed in a liquid solution and printed onto the substrate in a controlled pattern. A flower-like molybdenum disulfide (MoS 2 )/nanodiamond (ND) nanocomposite was successfully prepared via an easy hydrothermal synthesis method and fabricated into humidity sensors in Figure 3 [106].…”

“…ND-PANI showed significant enhancement in abrasion resistance as ND has high abrasion resistance and can increase the abrasion resistance and strengthen the mechanical properties, absorbing the applied energy during abrasion [134,135]. Recently, a pressure sensor device was made of a locally synthesized diamond layer [105]. The rear side of a pressure sensor diaphragm was prepared with an additional diamond layer as protective coating against harsh media, because of the diamond's chemical inertness and resistance.…”