Abstract: A composite dielectric layer (102). A first layer (112) of the composite dielectric layer (102) has a small to no nitrogen concentration. A second layer (114) of the composite dielectric layer (102) has a larger nitrogen concentration (e.g., 5-15%). The composite dielectric layer (102) may be used as a thin gate dielectric wherein the second layer (114) is located adjacent a doped gate electrode (110) and has sufficient nitrogen concentration to stop penetration of dopant from the gate electrode (110) to the channel region (108). The first layer (112) is located between the second layer (114) and the channel region (108). The low nitrogen concentration of the first layer (112) is limited so as to not interfere with carrier mobility in the channel region (108).

Abstract: A CMOS semiconductor structure having insulation sidewall spacers whose width is selected independently for NMOS and PMOS devices. The width of the spacer is selected to reduce hot electron injection in the N channel device and to insure that the gate and source regions are aligned with or underlap the gate in the P channel device. A narrower spacer is used for the P channel device than for the N channel device which permits the formation of a P channel device having a threshold voltage less than 1 volt.