Device parameter variations of n-MOSFETS with dog-bone layouts in 65nm and 40nm technologies

In this paper, variations of device parameters, such as threshold voltage (Vth) and saturation current (Idsat), of the devices with and without dog-bone-shaped active-area are investigated with a set of test structures in both 65nm and 40nm CMOS technology processes, respectively. The experiments show that variations of Vth/Idsat of dog-bone devices are more serious than the non-dog-bone device. At 65nm technology node, the inter-die absolute variation of the measured Idsat of dog-bone devices can reach 19.51% while that of standard devices is 11.31%. At 40nm technology node, the inter-die absolute variation of the measured Idsat of dog-bone devices can reach 21.29% while that of non-dog-bone devices is 15.11%. Moreover, the maximum intra-die performance deviation of dog-bone devices from standard devices can be 24% at a 65nm technology and about 42% at a 40nm technology. SPICE simulations show that the device performance variation is mainly due to the channel-width difference caused by photolithography effect. Therefore, it is very important to study both design-for-manufacturability (DFM) and resolution-enhancement-technology (RET) techniques to optimize the design and fabrication of dog-bone devices for IC designs in 65nm and below processes.