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  Semiconductor deviceUSPTO Application #: 20060273408Title: Semiconductor device Abstract: A semiconductor device includes a substrate, and a gate electrode on the substrate via a gate insulating film. The gate insulating film includes a base interface layer on the substrate, metal silicate film on the base interface layer and containing a metal, oxygen, and silicon, and a nitrogen-containing metal silicate film on the metal silicate film, and containing the metal, oxygen, silicon, and nitrogen and including nitrogen in a range from ten atomic % to thirty atomic %, and the metal silicate film contains the metal in a concentration higher than metal concentration of said nitrogen-containing metal silicate film. (end of abstract)
Agent: Leydig Voit & Mayer, Ltd - Washington, DC, US Inventors: Satoshi Kamiyama, Tsunetoshi Arikado Related Keywords: concentration, electrode, interface, metal, semiconductor, semiconductor device, silicon, substrate USPTO Applicaton #: 20060273408 - Class: 257401000 (USPTO) Related Patent Categories: Active Solid-state Devices (e.g., Transistors, Solid-state Diodes), Field Effect Device, Having Insulated Electrode (e.g., Mosfet, Mos Diode), Insulated Gate Field Effect Transistor In Integrated Circuit, With Specified Physical Layout (e.g., Ring Gate, Source/drain Regions Shared Between Plural Fets, Plural Sections Connected In Parallel To Form Power Mosfet) The Patent Description & Claims data below is from USPTO Patent Application 20060273408. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor device using a metal silicate film as a gate insulating film, to a method for manufacturing such a semiconductor device, to an apparatus being available for forming film in such a semiconductor device, and to method being available for forming high-dielectric-constant film in such a semiconductor device. [0003] 2. Background Art [0004] Accompanying the miniaturization of semiconductor devices, the reduction of thickness of gate insulating films has been demanded. The reduction of thickness of silicon oxide films and silicon oxynitride films (hereafter referred to as "silicon oxide film and the like"), which are used as conventional gate insulating films, is limited due to increase in leak current, and it is difficult to reduce the SiO.sub.2-converted film thickness to 1.5 nm or less. Therefore, there has been proposed a method for inhibiting leak current by using a high-dielectric-constant film, such as a metal oxide film, a metal silicate film and a metal aluminate film, which has a higher specific inductive capacity higher than that of silicon oxide film and the like as the gate insulating film; and by increasing the physical film thickness of the gate insulating film. [0005] However, when the high-dielectric-constant film is used as the gate insulating film, and a polysilicon electrode is used as the gate electrode, there has been a problem that impurities doped in the polysilicon electrode diffuse into the substrate through the gate insulating film when the impurities are activated, and the transistor properties are deteriorated. [0006] In order to solve this problem, a method for introducing nitrogen into the high-dielectric-constant film has been proposed. [0007] Specifically, there has been proposed a method for forming a high-dielectric-constant film composed of a zirconium oxynitride layer or a hafnium oxynitride layer, by forming a metal layer composed of zirconium or hafnium on a substrate, and oxynitriding the metal layer (refer to e.g., Japanese Patent Laid-Open No. 2000-58832). [0008] Furthermore, there has also been proposed a method for laminating a lower barrier film consisting of a hafnium-containing silicon oxynitride film, a high-dielectric-constant film consisting of a silicon-containing hafnium oxide film, and an upper barrier film consisting of a silicon-containing hafnium oxide film that contains nitrogen to form a gate insulating film and for controlling the composition of a metal (M), oxygen (O), nitrogen (N) and silicon (Si) in the high-dielectric-constant film and the lower barrier film (refer to e.g., Japanese Patent Laid-Open No. 2003-8011). [0009] In a thin-film formation using a high-dielectric-constant material, the ALD (atomic layer deposition) method is generally used. In this method, material gasses are alternately supplied while resetting the chamber to the original state to form each atomic layer. [0010] For example, the formation of a hafnium oxide (HfO.sub.2) film as a high-dielectric-constant film will be specifically described. First, the chamber is evacuated, argon gas is flowed in the chamber, and the pressure in the chamber is maintained to 0.2 Torr. In this state, hafnium tetramethylethylamide [Hf(N(CH.sub.3)(C.sub.2H.sub.5).sub.2).sub.4] is flowed into the chamber while controlling the flow rate, and the Hf material is vaporized and adsorbed on the surface of the substrate. Then, the chamber is purged, and an oxidizing gas such as ozone gas is introduced. Thereafter, the chamber is purged. By repeating such steps for several tens of times, a hafnium oxide (HfO.sub.2) film of a thickness of several nanometers can be formed on the surface of the substrate. [0011] The introduction of nitrogen into a high-dielectric-constant film reduces flat-band-voltage shift (hereafter referred to as "Vfb shift") due to the diffusion of impurities. This is estimated because the high-dielectric-constant gate insulating film is densified by nitriding treatment, and the diffusion of impurities is restricted. [0012] However, in the above-described conventional method, initial Vfb shift due to the effect of fixed charge or the like is large, and there has been a problem that satisfactory transistor characteristics cannot obtained particularly in P-channel MIS transistors. [0013] In addition, a high-dielectric-constant thin film formed using the ALD method generally contains several percent impurities. This is considered because carbon (C), hydrogen (H) or chlorine (Cl) included in material gas using the ALD method remains and is incorporated in the formed film. The impurities remaining in the high-dielectric-constant film may cause fixed charge and trap, and the characteristics of the film is damaged. SUMMARY OF THE INVENTION [0014] The one object of the present invention is to restrict initial Vfb shift, to form a gate insulating film having high film quantity, and to achieve satisfactory transistor characteristics. [0015] Another object of the present invention is to lower the impurity content in the high-dielectric-constant film of the gate insulating film. [0016] According to one aspect of the present invention, a semiconductor device comprises a substrate, a gate insulating film and a gate electrode. The gate insulating film is formed on the substrate, and has a nitrogen-containing metal silicate film or a nitrogen-containing metal aluminate film that contains a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less on the uppermost layer. The gate electrode is formed on the gate insulating film. [0017] Another aspect of the present invention, a semiconductor device comprises a substrate, a gate insulating film, and a gate electrode. The gate insulating film is formed on the substrate and has a base interface layer, a metal silicate film and a nitrogen-containing metal silicate film. The base interface layer is formed on the substrate. The metal silicate film is formed on the base interface layer, and contains a metal, oxygen and silicon. The nitrogen-containing metal silicate film contains a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less, oxygen, silicon, and nitrogen. The gate electrode formed on the gate insulating film. [0018] Another aspect of the present invention, in method for manufacturing a semiconductor device, a base interface layer is formed on a substrate. A metal silicate film containing a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less is formed on the base interface layer. A nitrogen-containing metal silicate film containing nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the upper layer of the metal silicate film. A gate electrode is formed on the nitrogen-containing metal silicate film. [0019] Another aspect of the present invention, in method for manufacturing a semiconductor device, a base interface layer is formed on a substrate. A metal silicate film containing a metal in a peak concentration of 5 atomic % or more and 40 atomic % or less is formed on the base interface layer. A nitrogen-containing metal silicate film containing a metal in a peak concentration of 1 atomic % or more and 30 atomic % or less and nitrogen in a peak concentration of 10 atomic % or more and 30 atomic % or less is formed on the metal silicate film. A gate electrode is formed on the nitrogen-containing metal silicate film. [0020] Another aspect of the present invention, a apparatus for forming a film comprises a housing, a table installed in the housing, for placing a substrate, a gas supply port for supplying a gas into the housing, a gas discharge port for discharging the gas in the housing out of the housing, and a heater. The heater is for heating the surface of the substrate by radiating light on the surface of the substrate placed on the table for a time up to several milliseconds. [0021] Another aspect of the present invention, in a method for forming a high-dielectric-constant film on a substrate, a first material gas that contains at least one element in elements constituting the high-dielectric-constant film is supplied into a housing wherein the substrate is placed. A second material gas that reacts with the first material gas and forms the high-dielectric-constant film is supplied into the housing. The surface of the substrate is heated by radiating light onto the surface of the substrate for a time up to several milliseconds. [0022] Other and further objects, features and advantages of the invention will appear more fully from the following description. Continue reading... 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