An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

The outstanding properties of SiO2, which include high resistivity, excellent dielectric strength, a large band gap, a high melting point, and a native, low defect density interface with Si, are in large part responsible for enabling the microelectronics revolution. The Si/SiO2 interface, which forms the heart of the modern metal–oxide–semiconductor field effect transistor, the building block of the integrated circuit, is arguably the worlds most economically and technologically important materials interface. This article summarizes recent progress and current scientific understanding of ultrathin (<4 nm) SiO2 and Si–O–N (silicon oxynitride) gate dielectrics on Si based devices. We will emphasize an understanding of the limits of these gate dielectrics, i.e., how their continuously shrinking thickness, dictated by integrated circuit device scaling, results in physical and electrical property changes that impose limits on their usefulness. We observe, in conclusion, that although Si microelectronic devices...

Ultrathin (<4 nm) SiO2 and Si-O-N gate dielectric layers for silicon microelectronics: Understanding the processing, structure, and physical and electrical limits

The paper consists of three parts. In the first part we review the basic experimental and theoretical results which shaped our present knowledge on point defects and diffusion processes in silicon. These results concern on one side oxidation effects which established that silicon self-interstitials and vacancies coexist in silicon and on the other side diffusion of gold into dislocation-free silicon which allowed to determine the self-interstitial contribution to silicon self-diffusion and to estimate the corresponding vacancy contribution. In the second part we discuss topics for which an understanding is just emerging within the framework of coexisting self-interstitials and vacancies: reaching of local dynamical equilibrium between self-interstitials and vacancies; rough estimates of the thermal equilibrium concentrations of self-interstitials and vacancies and their respective diffusivities, and finally, various possibilities to generate an undersaturation of self-interstitials. In the third part we examine swirl defect formation in silicon in terms of vacancies and self-interstitials.

Point defects, diffusion processes, and swirl defect formation in silicon

A memory cell array has a first and a second storage area. The first storage area has a memory elements selected by an address signal. The second storage area has a memory elements selected by a control signal. A control circuit has a fuse element. When the fuse element has been blown, the control circuit inhibits at least one of writing and erasing from being done on the second storage area.

Nonvolatile Semiconductor Memory Device

The present invention generally provides improved adhesion and oxidation resistance of carbon-containing layers without the need for an additional deposited layer. In one aspect, the invention treats an exposed surface of carbon-containing material, such as silicon carbide, with an inert gas plasma, such as a helium (He), argon (Ar), or other inert gas plasma, or an oxygen-containing plasma such as a nitrous oxide (N 2 O) plasma. Other carbon-containing materials can include organic polymeric materials, amorphous carbon, amorphous fluorocarbon, carbon containing oxides, and other carbon-containing materials. The plasma treatment is preferably performed in situ following the deposition of the layer to be treated. Preferably, the processing chamber in which in situ deposition and plasma treatment occurs is configured to deliver the same or similar precursors for the carbon-containing layer(s). However, the layer(s) can be deposited with different precursors. The invention also provides processing regimes that generate the treatment plasma and systems which use the treatment plasma. The carbon-containing material can be used in a variety of layers, such as barrier layers, etch stops, ARCs, passivation layers, and dielectric layers.

Plasma treatment to enhance adhesion and to minimize oxidation of carbon-containing layers

A non-volatile semiconductor memory device comprises a substrate (1) a source region (3) and a drain region (4); a channel region (5) between the source and drain regions; first and second insulating layers (6, 8) over the channel region; and a floating-gate (7) or traps (7 min ) between the first and second insulating layers. In the first insulating layer the gap of an energy band thereof increases from the region of the substrate to the region of the floating-gate or the traps.

Non-volatile semiconductor memory device.

It has been found that can be converted directly to silicon nitride or oxynitride at the surface of films by heating oxidized silicon wafers in anhydrous ammonia gas. At temperatures above 900°C, nitrided films have graded composites with respect to their nitrogen fraction. This analysis was performed by AES, infrared transmittance spectroscopy, and etch‐rate profiles. Nitrided surface regions on films, in which the nitride fraction ranged from 10% to 50%, showed remarkable masking effects against subsequent oxidation at high temperatures.

Direct Thermal Nitridation of Silicon Dioxide Films in Anhydrous Ammonia Gas

Very thin uniform silicon nitride films less than 100A have been obtained on silicon wafers by direct thermal reaction with nitrogen at temperatures ranging from 1200° to 1300°C. Small amounts of water or oxygen in reaction mixture caused vapor etching which gave rise to local crystallization. By eliminating both from the reaction ambient to less than 1 ppm, amorphous silicon nitride films can be deposited. These films have been found to have properties similar to those of CVD by investigations of Auger electron spectroscopy, infrared spectroscopy, and ellipsometry. Remarkable masking effects of the films against oxidation and phosphorus diffusion have been found.

Very Thin Silicon Nitride Films Grown by Direct Thermal Reaction with Nitrogen

Amorphous and uniform silicon nitride films with thicknesses of less than 100 A have been thermally grown on silicon wafers by employing purified ammonia gas. The films are much denser than conventional CVD Si3N4 films. The MNS (metal‐thermal nitride‐silicon) structures have very low Nss in the order of 3×1010 cm−2 eV−1 and an effective electron mobility of larger than 800 cm2/V sec in the fabricated n‐channel MNSFFT.

Thermally grown silicon nitride films for high-performance MNS devices

An insulative film, such as SiO 2 , Si 3 N 4 and PSG films, for example, is commonly used the passivation film or gate electrode of MISFETs. Stability of the insulative films during the production or operation of the semiconductor devices is enhanced by providing an insulative film which is formed by nitridation, for example, in an NH 3 gas, of an SiO 2 film, preferably a directly thermally oxidized film of silicon. The insulative film according to the present invention is used for a gate insulation film in MISFETs, a capacitor or passivation film for semiconductor devices, and as a mask for selectively forming circuit elements of semiconductor devices. The process for forming the insulative film may comprise successive nitridation, oxidation and nitridation steps.

Takao Nozaki

Papers

Non-volatile semiconductor memory device.

Direct Thermal Nitridation of Silicon Dioxide Films in Anhydrous Ammonia Gas

Very Thin Silicon Nitride Films Grown by Direct Thermal Reaction with Nitrogen

Thermally grown silicon nitride films for high-performance MNS devices

Process for producing a semiconductor device having a silicon oxynitride insulative film