Analog and RF Characteristics of Power FinFET Transistors With Different Drain-Extension Designs

Analog and RF characteristics of power FinFET transistors with different drain-extension structures are investigated for microwave integrated circuit applications. The power FinFETs were designed based on the drain-extended MOSFET structure and fabricated using a standard low-voltage FinFET process. Three various drain-extension configurations are demonstrated and compared. With the low-doped drain extension, the breakdown voltage of power FinFETs is higher than 6.5 V for all samples. For standard power devices, where the drain extension is performed with narrow fins, a high drain resistance is inevitable, resulting in high on-resistance and poor analog and RF performances. For devices with wide drain-extension fins (wide drain FinFET) or a planar drain extension (hybrid FinFET), lower drain resistances are obtained owing to the larger extension width. Therefore, the on-resistances of the wide drain and hybrid devices are much lower than that of the standard counterpart. Moreover, these devices with modified drain extensions also exhibit better analog and RF behaviors. The cutoff frequency of power FinFETs is boosted from 30 to 53 GHz when the drain extension is changed from narrow fins to a planar layout. These experimental results indicate that RF power FinFETs with good performance would be realized with the modified drain-extension designs.