A CMOS-Process-Compatible Low-Voltage Junction-FET with Adjustable Pinch-Off Voltage

A novel horizontal n-channel junction field-effect transistor (n-JFET) device is proposed and verified in a 0.25-μm bulk CMOS process. This horizontal JFET consists of alternating n- and p-regions formed by using the P-type electro-static discharge (ESD) implantation. P-type ESD implantation has been an optional and commonly well supported process step by most of foundries to improve ESD robustness of the I/O devices. Device parameters such as the pinch-off voltage (V_P) and the zero-bias drain current (I_DS0) of the proposed n-JFET device can be modified by adjusting the P+ separation (L) in the layout. With the adjustable pinch-off voltages, this device can be used for different circuit applications. The 2-D device simulations with technology computer aided design are used to analyze the depletion region and to verify the pinch-off voltage under different L values. The pinch-off voltage remains almost unchanged with the temperature variations. In addition, SPICE simulation results show good agreement with the experimental silicon (Si) data in term of I_D-V_D and I_D-V_G.