Performance Improvement of AlN-Based RRAMs Using Ag Layer for Hardware Security Applications

In this study, the 8 \times 8 aluminum nitride (AlN)-based complementary resistive switching (CRS) resistive random access memory (RRAM) crossbar array has been fabricated and was applied for a hardware security. Since CRS has a nonlinear \textit{I} - \textit{V} characteristic curve, it can effectively alleviate the actual impact caused by sneak current. A 5 nm silver electrode auxiliary layer is inserted between the electrode and the resistance switching layer to form a titanium nitride (TiN)/Ag/AlN/Pt/AlN/Ag/TiN seven-layer structure. The ultimate result here shows that the forming voltage of the device has eventually dropped from 5.5 to 2.8 V and the nonlinearity of \textit{I} - \textit{V} has gradually increased from 10.5 to 255 so that the number of arrays can ideally be expanded to more than \text{426} \times \text{426} bits. In addition, because a small amount of silver ions formed a relatively discontinuous conductive filament (CF), the device with an auxiliary layer of 5 nm Ag has a wider high-resistance state distribution. Therefore, it is suitable as the source of physical unclonable function (PUF) key generation for hardware security. After being compared by the read circuit comparator, we have generated a RRAM PUF key with reliability 99.1%, uniformity 49.5%, and randomness 48.9%. To authors' knowledge, it is first report about nitride-based CRS RRAM as PUF for hardware security applications.