In the past decade, aluminum scandium nitride (AlScN) with a high Sc content has shown ferroelectric properties, which provides a new option for CMOS-process-compatible ferroelectric memory, sensors and actuators, as well as tunable devices. In this paper, the ferroelectric properties of $A{l}_{0.7}S{c}_{0.3}N$ grown on different metals were studied. The effect of metal and abnormal orientation grains (AOGs) on ferroelectric properties was observed. A coercive field of approximately 3 MV/cm and a large remanent polarization of more than 100 μC/cm² were exhibited on the Pt surface. The $A{l}_{0.7}S{c}_{0.3}N$ thin film grown on the Mo metal surface exhibited a large leakage current. We analyzed the leakage current of $A{l}_{0.7}S{c}_{0.3}N$ during polarization with the polarization frequency, and found that the $A{l}_{0.7}S{c}_{0.3}N$ films grown on either Pt or Mo surfaces have large leakage currents at frequencies below 5 kHz. The leakage current decreases significantly as the frequency approaches 10 kHz. The positive up negative down (PUND) measurement was used to obtain the remanent polarization of the films, and it was found that the remanent polarization values were not the same in the positive and negative directions, indicating that the electrode material has an effect on the ferroelectric properties.

In this study, a CMOS compatible capacitive humidity sensor structure was designed and fabricated on a 200 mm CMOS BEOL Line. A top Al interconnect layer was used as an electrode with a comb/serpent structure, and graphene oxide (GO) was used as sensing material. XRD analysis was done which shows that GO sensing material has a strong and sharp (002) peak at about 10.278°, whereas graphite has (002) peak at about 26°. Device level CV and IV curves were measured in mini-environments at different relative humidity (RH) level, and saturated salt solutions were used to build these mini-environments. To evaluate the potential value of GO material in humidity sensor applications, a prototype humidity sensor was designed and fabricated by integrating the sensor with a dedicated readout ASIC and display/calibration module. Measurements in different mini-environments show that the GO-based humidity sensor has higher sensitivity, faster recovery time and good linearity performance. Compared with a standard humidity sensor, the measured RH data of our prototype humidity sensor can match well that of the standard product.

Magnetotransport measurements were performed on a cross-junction made from polycrystalline graphene grown at a low temperature. The Shubnikov-de Haas oscillation is observed, from which the cyclotron mass m_c can be derived varying from 0.043 to 0.055 times that of free electron. The changing rate of electron temperature is found much lower than that in pristine graphene via the universal electron heating study. Investigations on the characteristic lengths of weak localization reveal that the atomically sharp defects dominate the elastic scattering process, while studies on the coherent rate report that the Nyquist effect governs the inelastic scattering process with a little modulation from the direct Coulomb interaction. The scattering lengths in the polycrystalline graphene are comparable to that of exfoliated graphene on SiO₂. These findings indicate that some key scattering parameters which characterize the excellent properties of intrinsic graphene are preserved in the polycrystalline graphene, which may find potential applications in interconnects of integrated circuit.

A common MEMS micro-bridge structure-based process was developed on 200 mm standard CMOS Al back end of line. Thick amorphous-Si (alpha-Si) film was developed and used as the sacrificial material with well-controlled film stress to improve the wafer warpage. Anchor/contact structure was formed by a trench first scheme with no metal or dielectric plug in it, and thin Ti/TiN bilayer barrier metal was used as an electrode layer to define the sensing material resistor with improved step coverage on the anchor sidewall. A wet etching process was introduced for electrode layer patterning with almost no damage to the sensing material. The micro-bridge structure-based bolometer device was fabricated and evaluated on this platform. Good electrical performance had been achieved, and after optimized stress engineering the range of the released micro-bridge surface height variation was controlled to less than 10%, which indicated that the process platform can well match the bolometer, micro-lens and related sensor requirements.

Polysilicon is the commonly used material for resistor device in standard CMOS technology. Due to the process limitation, polysilicon resistor has the problem of high resistance variation and high temperature coefficient of resistance (TCR), which may cause performance degradation in analog circuit design. In this work, high resistivity TaN metal film was developed and integrated in thin TaN metal resistor structure, which was fabricated on 200mm wafer CMOS Cu-BEOL. The metal resistor performance was evaluated to check its potential value in CMOS resistor device application.