Abstract: In order to reduce capacitance of a feedback section of an operational amplifier provided in a semiconductor integrated device, an active filter includes an operational amplifier in which a plurality of capacitive elements are connected between (i) an output terminal and (ii) an inverting input terminal or an input terminal. This arrangement does not require any special technique and amendment of an ordinary integrated circuit process. Further, this arrangement ensures small capacitance in the feedback section of the operational amplifier, while preventing deterioration in S/N ratio, and increases in switching noise and power consumption.

Abstract: In a multi-terminal MOS varactor, a floating electrode 8 of a MOS capacitor (Cf) 5 is connected to one of two terminals of each of a plurality of capacitors (C1-Cn) 6-1 through 6-n. To the other terminals (Vg1-Vgn) 9-1 through 9-n of the respective capacitors (C1-Cn) 6-1 through 6-n, control voltages Vg1-Vgn are applied, and a terminal (Vn) 11 of the MOS capacitor (Cf) 5, the terminal being on the side of a well, receives a control voltage. In the multi-terminal MOS varactor with the arrangement above, it is possible to progressively change the valid electrostatic capacity C of the other terminal (Vgj) 9-j of an arbitrary capacitor (Cj) 6-j, by changing the control voltage. Since electrostatic capacity can be progressively changed in this MOS varactor, adopting this MOS varactor to an oscillator enables to control a frequency and sensitivity of the oscillator.

Abstract: A semiconductor device including an insulating film, a plurality of word lines parallel to one another, a gate insulating film and a first conductivity type semiconductor layer that are formed in this order, wherein the surface of said insulating film is rendered flat with respect to the surface of the word lines, and the first conductivity type semiconductor layer includes bit lines comprising a plurality of second conductivity type high concentration impurity diffusion layers crossing the word lines and parallel to one another.

Abstract: A SOI semiconductor device comprises a resistor body which is formed of a top semiconductor layer in a SOI substrate having an embedded dielectric film and the top semiconductor layer formed on the embedded dielectric film and which is dielectrically isolated by an insulating film, wherein a resistance value of the resistor body is set to be a predetermined value by the concentration of impurities contained in the top semiconductor layer and by the dimension of the resistor body.

Abstract: A method of producing a SOI MOSFET which includes a fully depleted channel region of a first conductivity type formed in a top semiconductor layer disposed on an insulative substrate, source/drain regions of a second conductivity type formed to sandwich the channel region and a gate electrode formed on the channel region with intervention of a gate insulating film, the method comprises: forming the channel region by setting an impurity concentration of channel edge regions of the channel region adjacent to the source/drain regions higher than an impurity concentration of a channel central region of the channel region, and setting a threshold voltage Vth0 of the channel central region and a threshold voltage Vthedge of the channel edge regions so that a change of the threshold voltage Vth0 with respect to a change of the thickness of the top semiconductor layer and a change of the threshold voltage Vthedge with respect to the change of the thickness of the top semiconductor layer are of opposite sign.

Abstract: In a multi-terminal MOS varactor, a floating electrode 8 of a MOS capacitor (Cf) 5 is connected to one of two terminals of each of a plurality of capacitors (C1-Cn) 6-1 through 6-n. To the other terminals (Vg1-Vgn) 9-1 through 9-n of the respective capacitors (C1-Cn) 6-1 through 6-n, control voltages Vg1-Vgn are applied, and a terminal (Vn) 11 of the MOS capacitor (Cf) 5, the terminal being on the side of a well, receives a control voltage. In the multi-terminal MOS varactor with the arrangement above, it is possible to progressively change the valid electrostatic capacity C of the other terminal (Vgj) 9-j of an arbitrary capacitor (Cj) 6-j, by changing the control voltage. Since electrostatic capacity can be progressively changed in this MOS varactor, adopting this MOS varactor to an oscillator enables to control a frequency and sensitivity of the oscillator.

Abstract: A method of producing a SOI MOSFET which includes a fully depleted channel region of a first conductivity type formed in a top semiconductor layer disposed on an insulative substrate, source/drain regions of a second conductivity type formed to sandwich the channel region and a gate electrode formed on the channel region with intervention of a gate insulating film, the method comprises: forming the channel region by setting an impurity concentration of channel edge regions of the channel region adjacent to the source/drain regions higher than an impurity concentration of a channel central region of the channel region, and setting a threshold voltage Vth0 of the channel central region and a threshold voltage Vthedge of the channel edge regions so that a change of the threshold voltage Vth0 with respect to a change of the thickness of the top semiconductor layer and a change of the threshold voltage Vthedge with respect to the change of the thickness of the top semiconductor layer are of opposite sign.

Abstract: A SOI semiconductor device comprises: a SOI substrate in which a buried dielectric film and a surface semiconductor layer are laminated; at least one well formed in the surface semiconductor layer; and at least one transistor which is formed in the well and has a channel region and source/drain regions in the surface semiconductor layer, wherein the well is completely isolated in the surface semiconductor layer and has a well-contact for applying a bias voltage to the well, the transistor is isolated by a device isolation film formed in a surface of the surface semiconductor layer, the channel region is partially depleted, and the surface semiconductor layer under the source/drain regions is fully depleted.

Abstract: A semiconductor device with a SOI structure comprises; a SOI substrate having a buried insulating film and a first conductivity type surface semiconductor layer on the buried insulating film; second conductivity type source and drain regions formed in the surface semiconductor layer; and a gate electrode formed over a first conductivity type channel region between the source and drain regions via a gate insulating film, wherein the source and drain regions are thinner than the surface semiconductor layer, and the channel region in the surface semiconductor layer has a first conductivity type high-concentration impurity diffusion region whose first conductivity type impurity concentration is higher than that in a surface of the channel region and which is adjacent to the buried insulating film.

Abstract: A SOI semiconductor device comprises: a SOI substrate in which a buried dielectric film and a surface semiconductor layer are laminated; at least one well formed in the surface semiconductor layer; and at least one transistor which is formed in the well and has a channel region and source/drain regions in the surface semiconductor layer, wherein the well is completely isolated in the surface semiconductor layer and has a well-contact for applying a bias voltage to the well, the transistor is isolated by a device isolation film formed in a surface of the surface semiconductor layer, the channel region is partially depleted, and the surface semiconductor layer under the source/drain regions is fully depleted.

Abstract: A SOI MOS field effect transistor includes: a superficial top semiconductor layer of a first conductivity type formed on a SOI substrate; source and drain regions of a second conductivity type arranged apart from each other on the top semiconductor layer; a P-type first channel region, an N+-type floating region, and a P-type second channel region formed in this order in a self-aligned manner and disposed between the N+-type source region and the N+-type drain region for an N-type MOSFET, or an N-type first channel region, a P+-type floating region, and an N-type second channel region formed in this order in a self-aligned manner and disposed between the P+-type source region and the P+-type drain region for a P-type MOSFET; and two gate electrodes for controlling the first and second channel regions, wherein a doping concentration of the second channel region adjacent to the drain region is lower than a doping concentration of the first channel region adjacent to the source regi

Abstract: A method for stabilizing an SOI semiconductor device which comprises the steps of: providing an SOI semiconductor device constituted of an SOI substrate including a support substrate, a buried insulating film formed on the support substrate and a surface semiconductor layer formed on the buried insulating film, source/drain regions formed in the surface semiconductor layer and a gate electrode formed on the surface semiconductor layer between the source/drain regions with intervention of a gate insulating film; and applying an electric stress between the support substrate and one of the source/drain regions so that a back channel is formed in a side of the surface semiconductor layer to the buried insulating film, thereby to introduce a capturing potential at least near an interface between said one of the source/drain regions and the surface semiconductor layer in the buried insulating film side.

Abstract: A semiconductor device includes a capacitor and an interconnect layer disposed on a semiconductor substrate. The capacitor is formed of a bottom electrode, a capacitor dielectric film and a top electrode. The layer is formed of a first interconnect layer and a second layer laminated on the first layer. The bottom electrode and the first layer are formed of a first metal layer. The top electrode and the second layer are formed of a second metal layer. The capacitor dielectric film is formed only on the bottom electrode.

Abstract: After a field oxide film is formed on a P-type semiconductor substrate, ion implantation of boron is carried out with respect to a whole surface of the substrate so that a channel stopper layer is formed. Then, a MOS FET is formed in an active region of the semiconductor substrate. Subsequently, ion implantation of phosphorus is carried out, by using a gate electrode of the MOS FET and the field oxide film as a mask, so that impurity layers which have the same type of conductivity as that of the channel stopper layer and has a concentration lower than that of the channel stopper layer are formed right under the source/drain regions of the MOS FET between the source/drain regions and the channel stopper layer.

Abstract: A field effect transistor is fabricated on an SOI substrate. N-type source and drain regions are arranged apart from each other in a semiconductor thin film of the SOI substrate. A P-type channel region is formed between the source and drain regions. Moreover, a gate electrode is formed over the channel region to cover the channel region through a gate oxide film. Extreme portions of the channel region, adjacent to the source and drain regions, have higher doping concentrations than in a center portion thereof. Furthermore, the gradient of the doping profile in the channel region is adjusted so as to reduce the current gain of a parasitic transistor in the field effect transistor. This structure enables a reduction of the channel length of the field effect transistor to the sub-half-micron order without deteriorating the electrical characteristics of the field effect transistor.