Kabushiki Kaisha Toshiba

Other

Marcon Electronics Co., Ltde.

Mitsuo Harata

Osamu Furukawa

Motomasa Imai

Koji Yamakawa

Kazuhide Abe

Hiroshi Toyoda

Yohachi Yamashita

Koji Sakui

Takashi Takahashi

Takaaki Yasumoto

Hideyuki Kanai

Nobuo Iwase

Masao Segawa

Hisakazu Iizuka

Osamu Takikawa

Yoshiko Kohanawa

Kazuo Nishijima

Seiichi Yoshida

Satoshi Mukaeda

Kiyoji Handa

A non-volatile semiconductor memory device, includes a memory cell having a capacitor formed by stacking a semiconductor layer and a ferroelectric layer between a pair of electrodes, the semiconductor layer and the ferroelectric layer forming a semiconductor-ferroelectric junction, a writing circuit in which a voltage higher than a coercive electric field of the ferroelectric material is applied to the capacitor of the memory cell to align a polarization direction of the ferroelectric layer in a predetermined direction so as to set a capacitance of the capacitor at a predetermined value, thereby writing data corresponding to the predetermined value of the capacitance, and a reading circuit in which a voltage less than the coercive electric field of the ferroelectric layer is applied to the capacitor of the memory cell in which the data is written, thereby reading the data.

Non-volatile semiconductor memory device capable of electrically

A semiconductor memory device comprises a ferroelectric capacitor, a voltage output circuit for outputting a first voltage for reversely polarizing the ferroelectric capacitor and a second voltage by which the polarization of the ferroelectric capacitor is not reversed, regardless of data stored in the ferroelectric capacitor, a first reference capacitor having a such a capacitance as to accumulate less charge than charge which the ferroelectric capacitor accumulates, when the second voltage is applied to the ferroelectric capacitor, a second reference capacitor having such a capacitance that as to accumulate greater charge than the charge which the ferroelectric capacitor accumulates while the ferroelectric capacitor is forwardly polarized, when the first voltage is applied to the ferroelectric capacitor, thus reversely polarizing the ferroelectric capacitor, a sense amplifier connected to the ferroelectric capacitor and the first or second reference capacitor, a reference-capacitor selecting circuit for connecting the first reference capacitor to the sense amplifier when the voltage output circuit outputs the second voltage, and connecting the second reference capacitor to the sense amplifier while the voltage output circuit outputs the first voltage, and a circuit for determining data from the presence or absence of an electric charge in the ferroelectric capacitors while the memory is set in volatile mode, and for determining data from the direction in which the ferroelectric capacitor is polarized, while the memory is set in nonvolatile mode.

Memory having ferroelectric capacitors polarized in nonvolatile mode

Ceramic composition and electronic part using the same

A ferroelectric capacitor includes a ferroelectric layer consisting of lead zirconate titanate formed on a silicon substrate, a plurality of rectangular trenches formed in the direction of thickness of the ferroelectric layer with a ferroelectric material therebetween, and first and second electrodes consisting of metal tungsten buried in the trenches to oppose each other with the ferroelectric material therebetween.

Ferroelectric capacitor and a semiconductor device having the same

A high-dielectric constant ceramic composite is provided in which an appropriate amount of glass component is added to a composite of the BaTiO.sub.3 -PbMO.sub.3 group having a low temperature coefficient in the dielectric constant thereof. The added glass component serves to maintain the satisfactory properties of the ceramic composite even after various types of reliability tests.

High-dielectric constant ceramic composite and ceramic capacitor elements

When a portion of the Pb of a Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 -based ceramic composition within the region bounded by lines connecting a, b, c, d, e and f points in the ternary composition diagram of the accompanying FIG. 1 is substituted by a small amount of Ca, a high dielectric constant type ceramic composition is obtained which has a small temperature coefficient of dielectric constant and which is effective as a material for multilayer ceramic capacitors.

High dielectric constant type ceramic composition

When a portion of the Pb of a Pb(Zn.sub.1/3 Nb.sub.2/3)O.sub.3 -based ceramic composition within the region bounded by lines connecting a, b, c and d points in the ternary composition diagram of the accompanying FIG. 1 is substituted by a small amount of Ba and/or Sr, a high dielectric constant type ceramic composition which has a small temperature coefficient of dielectric constant and which is effective as a material for multilayer ceramic capacitors is obtained.

Disclosed is a thick film capacitor comprising (a) a sintered layer of a ferroelectric material mainly consisting of one or more ferroelectric inorganic compounds having a perovskite structure and an inorganic binder having a eutectic composition which experiences a liquid phase at a temperature lower than the sintering temperature of the ferroelectric inorganic compounds, and (b) at least two electrodes formed on both surfaces of the sintered layer of the ferroelectric material. In the thick film capacitor of this invention, the perovskite structure of the ferroelectric inorganic compounds is not destroyed upon sintering. Therefore, a high degree of sintering, a good dielectric characteristic and high moisture and migration resistances can be obtained.

Thick film capacitor

To obtain a ceramic material having a high dielectric constant (K=2300 to 7000), a high insulation resistance (CR=4000 to 18000 ohmF), a low temperature dependence (.+-.10%) to (.+-.22, -33%) upon dielectric constant over a wide temperature range (-55 and +125.degree. C.) and a relatively low sintering temperature (1000.degree. C. to 1250.degree. C.), BaTiO.sub.3 powder at least 50 wt % of which is 0.7 to 3 .mu.m in particle size) is mixed with another compound with perovskite structure mainly composed of oxides of Pb, Ba, Sr, Zn, Nb, Mg and Ti before sintering. Further, part of Ti of BaTiO.sub.3 is substitutable with Zr or Sn, and part of Ba of BaTiO.sub.3 is substitutable with Sr, Ca or Ce.

High dielectric constant ceramic material and method of manufacturing

A method is disclosed which manufactures a recording head adapted to be moved relative to a recording medium, which is comprised of a conductive substrate and dielectric layer formed on the conductive substrate, to permit data to be recorded on the recording medium with the use of a conductive/magnetic toner on the recording medium. A conductive/magnetic sheet is attached to an insulating substrate of a first size with an adhesive layer therebetween, the first size of the insulating substrate is greater than a second size thereof defined by an insulating substrate of a finally completed recording head. The conductive/magnetic sheet is selectively etched to form an array of slits at a predetermined interval with both ends of the slits located beyond the side edges of an insulating substrate of a finally completed recording head. At one side edge portion of the conductive/magnetic sheet the conductive/magnetic sheet is electroplated to form a plated layer for a bonding pad. Those areas of the conductive/magnetic sheet, plated layer and insulating substrate, which are located beyond the side edge of the insulating substrate of the finally completed recording head, are cut to form a parallel array of electrodes and a bonding pad on one side edge portion of the conductive/magnetic electrodes.

Magnetic recording head and method for manufacturing

In a thermal head having a substrate and a heating resistor of thin film type formed thereon, the heating resistor is a deposited metal oxide film essentially consisting of ruthenium oxide and an oxide of at least one metal M selected from the group consisting of Ca, Sr, Ba, Pb, Bi and Tl. The deposited metal oxide film has an atomic ratio M/Ru of the metal M to ruthenium of 0.6 to 2.

Growing community of inventors

Kawasaki, Japan

Mitsuo Harata