Impact of Thermal Boundary Resistance on Thermoelectric Effects of the Blade-Type Phase-Change Random Access Memory Device

Phase-change random access memory (PCRAM) is widely regarded as one of the most promising candidates to replace Flash memory as the next generation of non-volatile memories due to its high-speed and low-power consumption characteristics. Recent advent of the blade-type PCRAM with low programming current merit further confirms its prospects. The thermoelectric effects existing inside the PCRAM devices have always been an important factor that determines the phase-transformation kinetics due to a fact that it allows PCRAM to have electric polarity dependent characteristics. However, the potential physics governing the thermoelectric effects for blade-type PCRAM device still remains vague. We establish a three-dimensional (3D) electro-thermal and phase-transformation model to study the influences of thermal boundary resistance (TBR) and device scaling on the thermoelectric effects of the blade-type PCRAM during its “RESET” operation. Our research shows that the presence of TBR significantly improves the electric polarity-dependent characteristics of the blade-type PCRAM, and such polarity-dependent characteristic is found immune to the scaling of the device. It is therefore possible to optimize the thermoelectric effects of the blade-type PCRAM through appropriately tailoring the TBR parameters, thus further lowering resulting power consumption.

Thermal Boundary Resistance Extraction of GaN-on-Diamond Substrate from Transmission Line Method Pattern Using Micro-Raman Spectroscopy and Thermal Simulation

Heat dissipation properties are very important in AlGaN/GaN RF high electron mobility transistor (HEMT) devices operating at high frequency and high power. Therefore, in order to extract the thermal conductivity of the substrate and device, which are essential for the analysis of the heat dissipation characteristics, various methods of extraction were attempted. And this experiments were conducted in parallel with micro-raman measurement and thermal simulation. As a result, it was possible to extract the thermal conductivity of each GaN-on-diamond epi layer by matching the thermal simulation data and the shift of the micro-raman peak according to various operating states and temperatures of the transmission line method (TLM) pattern. In particular, we tried to extract the thermal boundary resistance (TBR) of the interface layer (SiNx) for adhesion between GaN and diamond, which greatly affects the thermal conductivity of the device, and successfully extracted the following thermal conductivity value of KTBR = 3.162·(T/300)−0.8 (W/mK) from GaN and diamond interface layer.