Semiconductor devices with threshold voltage modulation layer
摘要
說(shuō)明書
Generally, the WFM layer of the NS NFETs 340 is configured to be different from the WFM layers of the NS PFETs 320, such that the work function of the NS NFET 340 is different from the work function of the NS PFET 320, thereby allowing the Vt of the resulting device 200 to be tuned separately according to a given design requirement. In one such example, the NS NFETs 340 may include TiAl while the NS PFETs 320 may include TaN. The reduction in device sizes introduces challenges in the fabrication of the metal gate stack, such as complexity of the pattering process to form the metal gate stack and the metal gate boundary diffusion. For example, the elements of the NS NFETs 340 (e.g., aluminum) may diffuse into the adjacent NS PFET 320, thereby causing issues such as Vt instability and undermining the device performance.
