Katsuyoshi Mitsui

Reverse short-channel effect due to lateral diffusion of point-defect induced by source/drain ion implantation

Presents a physical model of reverse short-channel effects on threshold voltage caused by lateral diffusion of the Frenkel pairs (interstitial-vacancy) induced by ion implantation in source/drain region of n-channel MOS devices. Based on the process and device simulation, it is shown that lateral diffusion of the Frenkel pairs enhances diffusion of channel dopant, and results in nonuniform lateral distribution. This phenomenon causes the threshold voltage increase in the short-channel devices. The authors extracted parameters on point-defect diffusion from the comparison of calculated results with experimental data on threshold voltage. Calculated arsenic profile in the source/drain region using those parameters shows good agreement with the experimental data measured by secondary ion mass spectroscopy (SIMS). The close agreement between simulation and experimental results both on the arsenic profile in source/drain region and threshold voltage confirms the validity of the model and extracted parameters. >

Gate capacitance characteristics of gate N/sup -/ overlap LDD transistor with high performance and high reliability

The authors present the gate capacitance characteristics of the gate/N/sup -/ overlap LDD (lightly doped drain) transistor. The gate capacitance was directly measured by a four-terminal method, using an LCR meter. The measured results for the overlap LDD were compared with those for the single drain and the LDD structure. It was demonstrated that the gate/drain capacitance for the overlap LDD is smaller than that for the single drain and as small as that for the LDD in spite of the large overlap length between the gate and the N/sup -/ region. This result was also confirmed by simulation, which indicates that the small gate/drain capacitance of the overlap LDD is due to the depletion of the N/sup -/ drain under the gate by the normal electric field from the gate and the lateral electric field at the drain.<<ETX>>

Reverse Short-Channel Effects due to the Lateral Diffusion of the Point-Defects Induced by the Source/Drain Ion Implantation

A physical model of reverse short-channel effect on the threshold voltage caused by the lateral diffusion of the Frenkel pairs (interstitial-vacancy) induced by tlie ion implantation in the source/drain region is presented. Based on the process and device simulation, it is shown that the lateral diffusion of the Frenkel pairs enhances the diffusion of the channel dopant, which results in the nonuniform lateral distribution of the channel dopant and in the increase in the threshold voltage as the channel length is reduced.

A high performance and highly reliable dual gate CMOS with gate/n/sup -/ overlapped LDD applicable to the cryogenic operation

A dual-gate CMOS structure has been developed which features an overlap LDD (lightly doped drain) NMOS with n/sup +/ poly gate and a surface channel PMOS with p/sup +/ poly gate whose source/drain and gate were salicided with low-resistance TiSi/sub 2/. The gate/n/sup -/ overlapped structure was fabricated by rotational oblique ion implantation. This CMOS structure can realize low-supply-voltage operation due to the small absolute value of threshold voltage without punchthrough. It is demonstrated that, using the overlap LDD NMOS, the circuit speed and the reliability can be improved, compared with the single and the conventional LDD NMOS. The cryogenic operation of the structure is examined.<<ETX>>