Nec Corporation

Other

Symetrix Corporation

Nippon Electric Co., Ltd.

Yoichi Miyasaka

Carlos Alberto Paz De Araujo

Akira Furuya

Joseph D Cuchiaro

Shintaro Yamamichi

Toshiyuki Sakuma

Shogo Matsubara

Takeshi Inoue

Takashi Hase

Hirohito Watanabe

Kiyoto Mori

Sadahiko Miura

Taku Yamate

Hayato Katsuragi

Toshinobu Shinnai

Hiroshi Morioka

A hydrogen barrier layer is formed above a ferroelectric thin film in an integrated circuit. The hydrogen barrier layer is directly over a protected segment of the ferroelectric thin film, while a sacrificial segment of the ferroelectric thin film extends laterally beyond the edges of the hydrogen barrier layer. The sacrificial segment absorbs hydrogen so that it cannot diffuse laterally into the protected segment of the ferroelectric thin film. After it absorbs hydrogen, the sacrificial segment is etched away to allow electrical connection to circuit layers below it. The ferroelectric thin film preferably comprises a layered superlattice compound. Excess bismuth or niobium added to the standard precursor solution of a strontium bismuth tantalum niobate compound helps to reduce hydrogen degradation of the ferroelectric properties.

Ferroelectric integrated circuit having low sensitivity to hydrogen exposure and method for fabricating same

A solution for forming a ferroelectric film characterized in that it contains at least one member selected from the group consisting of modified silicone oil and fluorinated surfactants, and a method for forming a ferroelectric film wherein said solution is used. A uniform film free from uneven coating (striation) is formed.

Solution and method for forming a ferroelectric film

In an integrated circuit, a stack of thin film layers comprising respectively a bottom electrode, a thin film of metal oxide, a top electrode, a lower barrier-adhesion layer, a hydrogen barrier layer, and an upper barrier-adhesion layer are patterned to form a memory capacitor capped with a self-aligned hydrogen barrier layer. Preferably, the top and bottom electrodes comprise platinum, the metal oxide material comprises ferroelectric layered superlattice material, the upper and lower barrier-adhesion layers comprise titanium, and the hydrogen barrier layer comprises titanium nitride. The hydrogen barrier layer inhibits diffusion of hydrogen, thereby preventing hydrogen degradation of the metal oxides. Part of the upper barrier-adhesion layer is removed in order to increase the electrical conductivity in the layer. Preferably, the memory capacitor is a ferroelectric nonvolatile memory. Preferably, the layered superlattice material includes strontium bismuth tantalate or strontium bismuth tantalum niobate.

Integrated circuit having self-aligned hydrogen barrier layer and method for fabricating same

A protective layer in a ferroelectric integrated circuit contains small amounts of oxygen to protect ferroelectric oxide material against hydrogen degradation during the fabrication process. Typically, the protective layer is a hydrogen diffusion barrier layer formed to cover a thin film of ferroelectric oxide material. In one method, a small amount of oxygen is included in the sputter atmosphere during deposition of a hydrogen diffusion barrier or a metallized wiring layer. The oxygen forms oxides that inhibit diffusion of hydrogen towards the ferroelectric oxide material. The oxygen forms a concentration gradient so that the oxygen concentration in the interior of the protective layer is zero, and the oxygen concentration near the surfaces of the layer is about two weight percent.

Ferroelectric integrated circuit with protective layer incorporating oxygen and method for fabricating same

After an interlayer insulating film is deposited on a silicon substrate, a contact hole or contact holes is or are formed at a desired position(s) and, then, after a polysilicon layer is deposited and the contact hole(s) is (are) embedded, the surface of the polysilicon layer is flattened by chemical and mechanical polishing using at least one of piperazine or colloidal silica slurry, and a barrier metal film,and a highly dielectric thin film,are deposited and processed to a desired size. Finally, an Al/TiN film,adapted for the upper electrode is formed. The leak current of the thin film capacitor which is obtained according to this method can be greatly reduced.

Method of manufacturing thin film capacitor

In a ferroelectric integrated circuit, a hydrogen barrier layer comprising titanium or titanium nitride or both is formed over a metal oxide element to protect it from hydrogen degradation. After hydrogen annealing and other process steps causing hydrogenating or reducing conditions, the hydrogen barrier layer is removed in a two-step etching process. The first etch step is a dry etch, preferably a standard ion-mill etching process, which rapidly removes most of the hydrogen barrier layer. The second step is a wet, chemical etch, preferably using a solution containing NH,OH, H,O,, and H,O, which selectively removes remnants of the hydrogen barrier layer from the circuit by oxidizing a chemical element of the barrier layer. The metal oxide material preferably comprises a layered superlattice compound.

Method of fabricating ferroelectric integrated circuit using dry and wet etching

An integrated circuit is formed that contains a ferroelectric element comprising metal oxide material containing at least two metals. An oxygen-recovery anneal is conducted in ambient oxygen at a temperature range from 300.degree. to 1000.degree. C. for a time period from 20 minutes to 2 hours. The oxygen-recovery anneal reverses the effects of hydrogen degradation and restores ferroelectric properties. The oxygen-recovery anneal is more effective as the annealing temperature and annealing time increase. Preferably the metal oxide element comprises a layered superlattice compound. Hydrogen degradation of the ferroelectric properties is minimized when the layered superlattice compound comprises strontium bismuth tantalum niobate and the niobium/tantalum mole ratio in the precursor is about 0.4. Hydrogen degradation is further minimized when at least one of the superlattice generator-element and the B-site element of the layered superlattice compound is present in excess of the amounts represented by the balanced stoichiometric formula of the compound.

Method of fabricating ferroelectric integrated circuit using oxygen to

An integrated circuit is formed that contains a ferroelectric element comprising metal oxide material containing at least two metals. Various methods and structures are applied to minimize the degradation of ferroelectric properties caused by hydrogen during fabrication of the circuit. Oxygen is added to the some elements of the integrated circuit to serve as a getter of hydrogen during fabrication steps. To minimize hydrogen degradation, the ferroelectric compound can be fabricated from a liquid precursor containing one or more of the constituent metals in excess of the amount corresponding to a stoichiometrically balanced concentration. A hydrogen barrier layer, preferably comprising titanium nitride, is formed to cover the top of the ferroelectric element. A hydrogen heat treatment in hydrogen gas is performed on the integrated circuit at a temperature from 200.degree. to 350.degree. C. and for a time period not exceeding 30 minutes to minimize degradation of the ferroelectric properties by hydrogen while restoring other properties of the integrated circuit. An oxygen recovery anneal at 800.degree. C. after high-energy hydrogen steps restores ferroelectric properties.

Method for fabricating ferroelectric integrated circuits

A thin film capacitor uses a dielectric film of high dielectric constant. A lower electrode is disposed on a contact, an interlayer insulating film is in contact with the lower electrode, a dielectric film of high dielectric constant covers the lower electrode, and an upper electrode covers the dielectric film. Thicknesses of the dielectric film at lower end portions of the lower electrode are thin but thick enough to make a leakage current value lower than a tolerable value thereof. At locations immediately below the lower electrode, the interlayer insulating film has portions whose thicknesses are larger than thicknesses of other portions thereof. The interlayer insulating film is such that, immediately below the regions of the dielectric film which are located at lower end portions of sides of the lower electrode and at which thicknesses of the dielectric film are very thin, the thicknesses of the interlayer insulating film are made larger than the rest thereof, or the dielectric film is such that lower end portions thereof are thin but thick enough to make a leakage current value lower than a tolerable value thereof. In this way, the occurrence of leakage current at the lower end portions of the lower electrode is suppressed.

Thin film capacitor with small leakage current and method for

In a semiconductor device which has a substrate, at least one thin film capacitor having a lower electrode layer deposited on the substrate, a dielectric layer overlaid on the lower electrode layer, and an upper electrode layer stacked on the dielectric layer, the lower electrode layer is surrounded by an insulator layer of Si.sub.3 N.sub.4.

Compact semiconductor device including a thin film capacitor of high

According to a method of fabricating a memory cell for a semiconductor integrated circuit, a lower electrode having a predetermined shape is formed on a semiconductor layer. A first insulating interlayer is formed on an entire surface of the semiconductor layer such that only a top surface of the lower electrode is exposed. A dielectric having a high dielectric constant is formed on the lower electrode and on the semiconductor layer. An upper electrode is formed on the dielectric having a high dielectric constant. The upper electrode constitutes a capacitor with the lower electrode through the dielectric.

Method of fabricating memory cell for semiconductor integrated circuit

A method for fabricating a thin-film capacitor for a semiconductor integrated circuit device includes steps of forming a barrier metal layer, forming a dielectric film, forming an interlayer insulating film, exposing the dielectric film and forming an upper electrode. The thin-film capacitor is fabricated by successively depositing the dielectric film and the upper electrode on a lower electrode. The dielectric film is made of a material having a high permittivity such as SrTiO.sub.3. The interlayer insulating film is left at side portions of the lower electrode and the dielectric film. In one aspect of the invention, even if the high permittivity film becomes thin at the side and end portions of the lower electrode, the interlayer insulating film can suppress an increase in a leakage current. In another aspect of the invention, the high permittivity film and lower electrode may be etched successively and collectively and an upper electrode is deposited thereon. It is possible to suppress an occurrence of short-circuiting of the electrodes and an increase in the leakage current at the side portions of the high permittivity film.

Method for fabricating thin-film capacitor with restrained leakage

A thin-film capacitor comprises a substrate, a first electrode, of polycrystalline silicon, a second electrode, a dielectric, and a third electrode such as aluminum in the structure stacked in sequence from bottom to top. The second electrode directly on which the dielectric layer is formed is made from a member selected from the group consisting of ruthenium, ruthenium oxide, ruthenium silicide, rhenium, rhenium oxide, rhemium silicide, osmium, osmium oxide, osmium silicide, rhodium, rhodium oxide, rhodium silicide, iridium, iridium oxide and iridium silicide.

Growing community of inventors

Tokyo, Japan

Yoichi Miyasaka