JPS60225434A - Formation of multi-element composite oxide film with high dielectric constant - Google Patents

Abstract

PURPOSE:To form an insulation film with a high dielectric constant, excellent in insulation, which can be applied for the capacitor of a high-quality cell part, on a semiconductor substrate by a method wherein thermal decomposition is carried out by adding a compound gas made mainly of an organic or inorganic compound of the main constituent of dielectric and containing another element, under irradiation with ultraviolet rays. CONSTITUTION:A film producer is composed of an ultraviolet ray source 101, a quartz tube 102, infrared ray heaters 103, raw material source bubblers 104 and 105, and ray material gas heaters 106 and 107. Light of 184.9nm wavelength emitted from a low-pressure mercury vapor lamp 101 is condensed by a reflection mirror 108, and the surface of a semiconductor condensed by a reflection mirror 108, and the surface of a semiconductor substrate 109 is irradiated with the light through the quartz tube 102. The substrate and the reaction gas are heated by the infrared ray heater 103 and a reflection mirror 110, thus carrying out vapor phase decomposition with photo energy and thermal energy; accordingly, a high-quality oxide can be deposited on the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for forming a high dielectric constant multi-component oxide film, and more particularly to a method for forming a high dielectric constant multi-component oxide film that includes ultraviolet irradiation.

(Prior Art) Integrated circuits formed on semiconductor substrates, particularly silicon semiconductor substrates, are becoming increasingly highly integrated and have a large capacity, and integrated circuits such as memory devices have increased to 1M bits or more. There is. In producing large-capacity devices, it is necessary to reduce the chip size as much as possible from the viewpoint of yield and cost, and various microfabrication techniques have been developed for this purpose.

Currently, in IC memories such as dynamic RAM, it is considered most suitable for miniaturization that the information storage section (hereinafter referred to as cell) is composed of one transistor and one information storage capacitor section. In the information storage method in this method, the area of the information storage capacitor portion of the cell occupies most of the semiconductor pellet. Therefore, the dynamic R according to this method
In order to suppress the increase in chip size due to the increase in the capacity of AM, the most effective means is to reduce the area of the information storage capacitor.

However, reducing the area of this information storage capacitor will not reduce the capacitance value if the dielectric constant of the dielectric is small and the film thickness is constant, but will reduce the amount of information signal stored in this capacitor. . This reduction in the amount of information signal is undesirable from the viewpoint of preventing the effect of erasure of memory contents (soft error) due to radiation. For this reason, in order to increase the capacitance value per unit of 1,000 areas, reduction of film thickness, lamination of capacitance parts, and materials with high dielectric constant are being considered. In DRAMs (1M bits), insulation reaches its limit in terms of withstand voltage, etc., and it can no longer be used in highly integrated memories of 1M or more. When forming a capacitive part in a stacked structure, the second and higher insulating films must rely on thermal oxidation of polycrystalline materials, which leaves problems with the insulation properties of the films. In addition, using a high dielectric material for the dielectric is advantageous because the film thickness can be increased, but the properties of the insulating film vary greatly depending on the film formation method, so various formation methods are required. has been considered, but no effective method has been found.

(Objective of the Invention) The object of the present invention is to solve the above-mentioned problems and to facilitate the increase in the capacity of integrated circuits and the reduction in chip size.
The present invention provides a method for forming a high dielectric constant multi-component oxide film.

(Structure of the Invention) The method for forming a high dielectric constant multi-component oxide film of the present invention includes arranging a film forming substrate inside a quartz hollow cylindrical tube, and injecting a plurality of gases, which are raw materials for a high dielectric constant thin film, into the quartz hollow cylindrical tube. The precursor gas is decomposed using a heating heater placed outside the quartz hollow cylindrical tube and ultraviolet light, and a high dielectric constant multi-component oxide film is formed on one main surface of the film forming substrate. It is constructed by phase growth.

- (Principle and operation of the invention) According to the present invention, while irradiating ultraviolet light, a compound gas containing an organic or inorganic compound containing an element that is the main component of a dielectric material is used as a main raw material, and a compound gas containing other elements is added to the main raw material. In addition, by performing thermal decomposition, a high dielectric constant,
An insulating film with excellent insulation properties and high quality that can be applied to the capacitive part of the cell part is formed.

According to the present invention, since vapor phase decomposition of the raw material gas that is a component of the dielectric film occurs, a desired film composition can be obtained by changing the type and partial pressure of the gas. A uniform solid solution composite oxide can be easily formed. By combining materials with different physical and chemical properties and forming a solid solution with a uniform composition, it is possible to form a film that combines these physical and chemical properties. It becomes possible to compensate for physical, physical, and chemical limitations.

Furthermore, since the vapor phase growth temperature can be lowered due to ultraviolet irradiation during vapor phase growth, it is effective for forming a dielectric film on a compound semiconductor substrate or the like whose composition changes due to high temperature treatment. In addition, in thermal oxidation of metals, volume expansion occurs when they turn into oxides, which causes a leakage current to flow in the film, but chemical vapor growth using ultraviolet irradiation can Since fine grains are deposited by low-temperature decomposition, such volume expansion does not occur, and by combining a material with a high dielectric constant and a material with low grain growth, it is possible to suppress the occurrence of cracks due to thermal annealing. Furthermore, a dielectric film with low leakage current can be formed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are schematic cross-sectional lines and explanatory diagrams of infrared and ultraviolet light sources of the optically excited high dielectric constant thin film forming apparatus used in this example. Note that in this example, T
Formation of an a-8j-0 type dielectric film will be described.

As shown in FIGS. 1 and 2, an ultraviolet light source 101, a quartz tube 102, an infrared heater 103, and raw material gas source bubblers 104, 105, here, T a as a raw material gas.
(OCtHi) * as source gas source bubbler 104 K
, 8i (QC,H,), as the raw material gas bubbler 105
I put it in. It also includes raw material gas heaters 106 and 107.

Further, in this apparatus, light with a wavelength of 184.91 tN emitted from the low-pressure mercury pump 101 is focused by the reflecting mirror 108 and irradiated onto the surface of the semiconductor device 109 through the quartz tube 102. Further, the substrate and the reaction gas are heated by the infrared heater 103 and the reflecting mirror 110, and gas phase decomposition can be performed using optical energy and thermal energy, thereby allowing oxides to be deposited on the substrate.

Since the gas source is liquid, the raw material gas source Babsy 104.1
At step 05, the heaters 106 and 10 are converted to Arf carrier gas.
It is heated and vaporized at step 7. The carrier gas can be any inert gas. Since Ta(OqHa)a has a low vapor pressure (0.15 Hg at 146°C), the heater 106
The temperature is set at 0°C to 290°C, and the flow rate is adjusted by the pulp 111. Since 8i(OQI-L)4 boils at normal pressure of 167°C, heating by the heater 107 may be from 20°C to 60°C. The flow rate of S i (OCJL,)+ is pulp 112
Adjust by. The reaction tube is heated with a ribbon heater 113 to prevent gas from condensing.

In this system, the vapor pressure of Ta(OC*Hs)s is low, so
Gas phase growth is performed under reduced pressure of 0.1 Torr to 1'l1orr. Gas is introduced through the gas inlet 114 so that the pressure in the reaction tube can be adjusted. The temperature inside the reaction tube is 300°C to 50°C.
It can be grown in the vapor phase at 0°C. The gas after the reaction is exhausted from the exhaust port 115. Also, the 'l'a-
The formation of an 8i-based composite oxide film suppresses the grain growth of Ta oxide that occurs near jD and 600°C due to the solid solution of Si element into Ta oxide, so the leakage current is reduced by high-temperature annealing at 600°C to 700°C. A film with a small amount of oxidation was formed.

In addition, Nb (0 Tsuru H6), Hf (O et H,)
It is also possible to introduce raw material gas such as , etc.

As a heating method, not only an infrared heater but also a thermal furnace can be used.

Note that although a silicon substrate is used as the substrate in this embodiment, it is not limited to a silicon substrate.

Dielectric films can be similarly formed on other semiconductor substrates or on insulating substrates such as ceramic substrates.

(Effects of the Invention) As explained above, according to the present invention, a high dielectric constant multi-component oxide film can be obtained, and this film is a dielectric film that exceeds the physical and chemical limits of a single oxide film. Also, if this is applied to integrated circuits, it will be possible to increase the capacity of the integrated circuit and further reduce the chip size.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views for explaining the optically excited high dielectric constant thin film forming apparatus used in the examples of the present invention, as well as explanatory views of the infrared and ultraviolet light sources. 101... Ultraviolet light source (low pressure mercury lamp), 10
2...Reactive quartz fα, 103...Infrared heater, 104.105... Raw material gas source bubbler, 106°107... Raw material gas heater,
108・Old...Reflector, 109...Semiconductor substrate, 110...Reflector, 111゜112...
...Flow #16 Pulp, 113... Ribbon heater, 114... Gas inlet, 115.
·····exhaust port. yF) 2 flash"'y

Claims (1)

[Claims] A film forming substrate is placed inside a quartz hollow cylindrical tube. A plurality of gases serving as raw materials for a high dielectric constant thin film are introduced into the quartz hollow cylindrical tube, and the raw material gases are decomposed by a heating heater placed outside the quartz hollow cylindrical tube and ultraviolet light, and the film forming substrate is decomposed over a lifetime. A method for forming a high dielectric constant multi-component oxide film, the method comprising growing a high dielectric constant multi-composite oxide film on a surface in a vapor phase.