A thin film transistor includes an active layer having an offset region formed between a channel region and a drain region, a first insulating film formed on an upper surface of the active layer, a gate electrode formed at a position opposing to the channel region with the first insulating film interposed, and a second insulating film formed at a position opposing to the offset region with the first insulating film interposed and including impurities for forming charges. The charges formed in the second insulating film are provided by implanting fluorine ions, for example, if the charges are to be negative charges. By this structure, the on current of the thin film transistor can be increased and the leak current can be reduced.
A TFT with a drain-offset structure is provided, which realizes a high ON current while keeping an OFF current at a low level. This TFT includes a substrate and a patterned semiconductor film formed on a main surface of the substrate. At least the main surface of the substrate has an insulating property. The patterned semiconductor film is made of a silicon-system semiconductor material and is not monocrystalline. The patterned semiconductor film includes a source region of a first conductivity type, a channel region of a second conductivity type opposite to the first conductivity type, a first drain region of the first conductivity type, and a second drain region of the second conductivity type. The first drain region serves as an offset region. A gate electrode is formed to be opposite to the channel region through a gate insulating film. The source region is formed on one end of the semiconductor film. The second drain region is formed on an opposite end of the semiconductor film to the source region. The channel region is formed to be adjacent to the source region and the first drain region. The first drain region is formed to be adjacent to the channel region and the second drain region.
A method for fabricating a semiconductor device for reducing coupling noise resulting from high integration of devices, comprises the steps of forming a plurality of metal wiring leads spaced from each other by a predetermined distance and arranged on a semiconductor substrate having a predetermined under layer; forming an insulating interlayer on an entire surface of the semiconductor substrate so that the metal wiring leads are covered with the insulating interlayer; and ion-implanting conductive impurities having a plurality opposite to each other into side end layers of the insulating interlayer disposed between the metal wiring leads so as to reduce the internal charges electrified due to an applied external electric field.
A semiconductor device having relatively low permittivity fluorine bearing oxide between conductive lines and a method for fabricating such a device is provided. At least two adjacent conductive lines are formed over a substrate. An oxide layer is formed between the adjacent conductive lines. A mask is formed over the oxide layer and selectively removed to expose a portion of the oxide layer between the adjacent conductive lines. A fluorine bearing species is implanted into the exposed portion of the oxide layer to reduce the permittivity of the oxide layer between the adjacent conductive lines. The permittivity or dielectric constant of the oxide layer between the adjacent conductive lines can, for example, be reduced from about 3.9 to 4.2 to about 3.0 to 3.5.
