Artur Balasinski

Lateral profiling of oxide charge and interface traps near MOSFET junctions

A technique for measuring the lateral distributions of both interface traps and trapped oxide charge near the source/drain junctions in MOSFETs is presented in detail. This technique derives from the charge pumping method, is easy to implement, and allows ready separation of the interface-trap and oxide charge components. Some illustrative results are given. The various issues involved in its implementation and its practical limitations are discussed. >

Pre‐Oxidation Fluorine Implantation into Si Process‐Related MOS Characteristics

MOS structures with fluorinated oxides were studied. Fluorine was introduced into the gate oxide by first implanting it into the Si wafer, followed by oxidation. The effect of rapid thermal annealing after F implantation was also investigated. Two of the most prominent effects resulting from this process observed were improved interface resistance to radiation and hot electron damage, with the degree of improvement depending on the F implantation dose and energy, and altered effective dopant concentration of the substrate at high F implant doses

Effects of X-ray irradiation on GIDL in MOSFETs

The effect of X-ray irradiation on the gate-induced drain leakage (GIDL) is shown to be mostly due to the electrostatic effect of the trapped positive charge in n-channel MOSFETs. In p-channel MOSFETs, in addition, irradiation increases the interface-state-assisted tunneling component of the GIDL. In both n- and p-channel MOSFETs, a forming gas anneal at 400 degrees C completely removes all effects of irradiation on the GIDL.<<ETX>>

Ionizing radiation damage near CMOS transistor channel edges

Enhanced radiation damage near channel edges of n- and p-channel MOS transistors has been observed from measurements of channel resistance and gate-induced drain leakage current. Good correlation between these two types of measurements has been established. The degree of such edge effects has been found to depend strongly on the process technology. In some cases, the radiation damage near the edge plays a major role in the total device degradation, and it becomes more important as the device size reduces. A comparison has been made among transistors fabricated with standard, fluorinated, and radiation-hardened oxides. The results suggest that it is possible to minimize the radiation-induced edge effects by the use of appropriate process conditions. >

Lateral distribution of radiation-induced damage in MOSFETs

Significant lateral nonuniformity of radiation-induced oxide charge and interface traps in short-channel CMOS transistors was observed. This nonuniformity affects device DC parameters. A modified charge pumping technique was used in this study. Its basic principles are briefly discussed. Results for MOSFETs irradiated under various bias conditions are presented. >

Impact of radiation-induced nonuniform damage near MOSFET junctions

Laterally nonuniform distributions of radiation-induced oxide charge and interface traps near MOSFET junctions have been found in a variety of samples. As revealed by three independent measurement techniques, the degree of nonuniformity depends strongly on the process technology. Such lateral nonuniformity could arise from the lateral variation of the oxide field near the channel edges during irradiation and the different diode properties in these regions compared to those in the main channel region. These channel edge effects can significantly affect MOSFET device parameters such as the threshold voltage, transconductance, channel resistance, and effective channel length. This is especially the case for submicron devices. Results from computer simulation indicate that the edge damage alone could contribute to a major portion of the transconductance degradation in irradiated submicron devices. >

Hot-carrier effects on interface-trap capture cross sections in MOSFETs as studied by charge pumping

A rapid charge-pumping method was used to measure the interface-trap parameters in MOSFETs. The geometric mean of the electron and hole interface-trap capture cross sections decreases significantly (as much as two orders of magnitude) after Fowler-Nordheim (F-N) injection, and gradually recovers toward its original value. This effect is consistent with the interface-trap transformation process observed in MOS capacitors.<<ETX>>

Reduction of interface‐trap density in metal‐oxide‐semiconductor devices by irradiation

Annealing of interface defects in metal‐oxide‐semiconductor (MOS) devices by x‐ray irradiation has been observed. The effect occurs in rad‐hard devices which had been previously damaged severely by high‐field Fowler–Nordheim electron injection, but has not been observed in standard MOS devices which are not radiation‐hardened. A mechanism based on the recombination‐enhanced‐defect‐reactions process is proposed to explain the results.

Enhanced electron trapping near channel edges in NMOS transistors

Charge trapping in the gate oxide of NMOS transistors due to constant-voltage Fowler-Nordheim injection was investigated. Results from several different measurement methods consistently indicated strongly enhanced electron trapping in the gate oxide near the channel edges and in the gate oxide overlaps above drain and source, although net positive charge was observed in the bulk of the channel. The edge trapping effect could increase the electrical channel length by as much as 0.5 mu m and is independent of the channel length. Possible reasons for the observed phenomena are discussed. >

Fluorinated CMOSFETs fabricated on (100) and (111) Si substrates

By introducing appropriate amounts of F into the gate SiO/sub 2/, the transconductance and channel mobility for both n- and p-channel MOSFETs made on either (100) or (111) Si substrate are improved, due to the reduced densities of interface traps and oxide charge. These results, coupled with its improved reliability against hot-carrier damage, make fluorinated oxide an attractive VLSI technology.<<ETX>>