(a) (b)

(c)

(d)

3D Heterogeneous Integration of GaN and Si: Intel researchers will describe how low-leakage, high-k dielectric enhancement mode GaN NMOS and Si PMOS transistors were built monolithically on a 300mm high-resistivity Si substrate. The GaN devices were built using MOCVD epitaxy, and the Si devices were built on top of them by means of a layer transfer process. The goal is to combine GaN’s high-frequency/-temperature/-power attributes with silicon CMOS circuitry’s digital signal processing, logic, memory and analog capabilities, to create compact devices for next-generation solutions for power delivery, RF and system-on-chip (SoC) applications. The researchers say both device types demonstrated excellent performance across a range of electrical specifications. For example, the GaN NMOS devices showed a low off-current (100pA/µm) and excellent RF performance/efficiency at both mmWave and sub-7GHz frequencies, while the Si PMOS devices demonstrated a high drive current (0.85mA/µm) and a low off-current (150pA/µm).

In the figures above, (a) is a schematic of the 3D heterogeneous integration of Si PMOS transistors stacked on top of GaN NMOS transistors; (b) is a 3D cross-sectional view of the completed 3D transistor stack; (c) is a cross-section of a fabricated access via through the top device layer, to access the bottom GaN NMOS transistor; and (d) shows the drive current and voltage relationships of the top and bottom layers, with matched drive current strength and OFF leakage.

(Paper #17.3, “3D Heterogeneous Integration of High-Performance High-k Metal Gate GaN NMOS and Si PMOS Transistors on 300mm High-Resistivity Si Substrate for Energy-Efficient and Compact Power Delivery, RF (5G and Beyond) and SoC Applications,” H. W. Then et al., Intel.)