KR20000004402A - Capacitor preparation method of semiconductor element - Google Patents

Abstract

The present invention provides a method of manufacturing a capacitor of a semiconductor device capable of forming an HSG thin film having a constant surface area by completely removing contaminants on the silicon surface on which the HSG thin film is formed before forming the HSG thin film.

The capacitor of the semiconductor device according to the present invention includes a hemispherical grain polysilicon thin film, and its storage electrode is formed as follows. First, a doped amorphous silicon film is formed on a semiconductor substrate as a material for a storage electrode, and the doped amorphous silicon film is etched in the form of a predetermined storage electrode. Then, the surface of the etched doped amorphous silicon film is treated with O ₂ plasma to remove contaminants present on the surface of the semiconductor layer, and a hemispherical grain polysilicon thin film is formed on the surface of the doped amorphous silicon film to form a storage electrode. .

Description

Capacitor Manufacturing Method of Semiconductor Device

The present invention relates to a method for forming a capacitor of a semiconductor device, and more particularly to a method for forming a capacitor of a semiconductor device using a hemispherical polysilicon film.

As the degree of integration of semiconductor memory devices such as DRAM (DRAM) increases, the cell area is reduced, while the capacitor must have a certain capacity, and therefore a capacitor having a large capacity in a small area is required. In contrast, conventionally, in order to maximize the capacity of a capacitor, an insulator having a high dielectric constant is used as a dielectric film, or a storage electrode is formed by using a hemispherical grain polysilicon (HSG) thin film to form a storage electrode. Increased surface area.

In general, HSG thin films are formed by utilizing the microcrystalline structural properties of polysilicon thin films to concave and convex their surfaces. However, in order to use the HSG thin film as a storage electrode, a separate doping process and a deglaze process have to be performed, which makes the process complicated. In addition, during the deglaze process, the surface of the HSG thin film is partially etched, thereby reducing the surface area of the storage electrode. In order to solve this problem, a selective HSG thin film formation method has been proposed in which a silicon seed is formed on a doped amorphous silicon film to perform high vacuum annealing to form an HSG thin film.

In the above-described selective HSG thin film formation method, shape characteristics such as grain size and density of the HSG thin film are sensitively changed depending on the degree of crystallization, impurity concentration, contaminants, and the degree of the silicon surface on which the HSG thin film is formed. However, since the silicon surface on which the HSG thin film is formed is contaminated by the etching process performed before the formation of the HSG thin film, it is difficult to form the HSG thin film having a constant surface area. In particular, when the dry etching process is performed with an etching gas containing a hydrocarbon gas before the formation of the HSG thin film, there is a problem that the HSG thin film is not formed or the grain size is very small, so that a constant surface area cannot be obtained. In addition, since contaminants generated by hydrocarbon gas have different concentrations in the plane perpendicular to the substrate and in the plane horizontal, when the HSG thin film is formed by the selective HSG thin film formation method described above, grain size and The problem arises that the density is formed differently. That is, because the hydrocarbon gas interferes with the seeding required when HSG is formed, and in severe cases, it inhibits the movement of silicon atoms around the seed and thus inhibits the growth of the HSG thin film. Moreover, since hydrocarbon gas has a strong bond with silicon on the silicon surface, there is a problem that contaminants generated by carbon gas are not completely removed even by cleaning with a chemical solution.

Accordingly, the present invention is to solve the above-mentioned problems, before forming the HSG thin film using the selective HSG forming method, completely removes contaminants on the silicon surface on which the HSG thin film is formed, HSG thin film having a constant surface area It is an object of the present invention to provide a method for manufacturing a capacitor of a semiconductor device capable of forming the same.

1A to 1C are cross-sectional views illustrating a method of manufacturing a stacked capacitor according to an embodiment of the present invention.

2A to 2C are cross-sectional views illustrating a method of manufacturing a cylinder type capacitor according to another embodiment of the present invention.

[Description of Code for Major Parts of Drawing]

10, 20: semiconductor substrate 11, 21: junction region

12, 22 insulating film 13, 23 doped amorphous silicon film

24: core insulating film

25 spacer formed of a doped amorphous silicon film

14, 26: HSG thin film 100, 200: storage electrode

The capacitor of the semiconductor device according to the present invention for achieving the above object is provided with a hemispherical grain polysilicon thin film, its storage electrode is formed as follows. First, a doped amorphous silicon film is formed on a semiconductor substrate as a material for a storage electrode, and the doped amorphous silicon film is etched in the form of a predetermined storage electrode. Then, the surface of the etched doped amorphous silicon film is treated with O ₂ plasma to remove contaminants present on the surface of the semiconductor layer, and a hemispherical grain polysilicon thin film is formed on the surface of the doped amorphous silicon film to form a storage electrode. .

In addition, the doped amorphous silicon film is etched using a gas containing a hydrocarbon, such as CHF ₃ gas, and the O ₂ plasma treatment is a direct method of generating a plasma by applying RF power to the substrate or indirectly generating a high power plasma on the substrate. proceeds to a method of applying, and proceeds using only O ₂ gas, or the process proceeds to a mixed gas of other gases and does not include the O ₂ gas and the carbon.

In addition, the hemispherical grain polysilicon thin film is formed by a selective hemispherical grain polysilicon thin film formation method of annealing after forming a seed on the surface of the semiconductor layer using SiH ₄ gas or Si ₂ H ₆ gas as the source gas.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention.

1A to 1C are cross-sectional views illustrating a method of manufacturing a stacked capacitor according to an embodiment of the present invention.

Referring to FIG. 1A, an insulating film 12 is formed on a semiconductor substrate 10 provided with a junction region 11. At this time, the insulating film 12 is formed of a doped oxide film, such as a BoroPhospho Silicate Glass (BPSG) film, a BSG film, and a PSG film, or an undoped oxide film such as a thermal oxide film or HTO. An insulating layer 12 is etched to expose a portion of the junction region 11 to form a contact hole, and an amorphous doped P-ion on the insulating layer 12 in an in-situ manner to fill the contact hole. The silicon film 13 is formed. At this time, the doped amorphous silicon film 13 is impurity containing a PH ₃ gas diluted with a silicon source gas such as SiH ₄ or Si ₂ H ₆ and an inert gas such as N ₂ and He, or a PH ₃ gas diluted with silicon gas. It is used as a source gas and forms at a temperature of about 530 ° C. or less. Then, the doped amorphous silicon film 13 is patterned on the doped amorphous silicon film 13 by photolithography and etching to define the capacitor region. At this time, the etching process is performed using a gas containing a hydrocarbon, such as CHF ₃ gas. Accordingly, as shown in FIG. 1A, contaminants in the form of Si-C bonds are generated on the surface of the doped amorphous silicon film 13 after etching.

Referring to FIG. 1B, after etching the doped amorphous silicon film 13, an O ₂ plasma process may be performed to form a CO ₂ bond to remove contaminants. In this case, the O ₂ plasma process may be performed by applying RF (Radio Frequency) power to the semiconductor substrate or indirectly applying plasma generated at high power to the substrate. In addition, the O ₂ plasma treatment proceeds using only O ₂ gas or by mixing with other gases that do not contain carbon such as N ₂ gas. The resulting substrate is then etched with an oxide etch solution to remove the oxide film that may form on the surface.

Then, as shown in FIG. 1C, the HSG thin film 14 is formed on the surface of the doped amorphous silicon film 13 by a selective HSG forming method to form the storage electrode 100 of the stacked capacitor. That is, an amorphous silicon film doped using SiH ₄ gas or Si ₂ H ₆ gas as a source gas in a vacuum or high vacuum state by using a single wafer type or batch wafer type device (13). An HSG thin film 14 is formed on the surface by forming a seed on the surface) and annealing to surface-shift the silicon atoms of the amorphous silicon film 13 doped about the seed. For example, in a high vacuum state, the pressure in the chamber is 10 ^-4 Torr or less and annealing is performed at a temperature equal to or higher than the temperature at the time of seed formation.

The above-described method can also be applied to a cylindrical capacitor manufacturing method.

2A to 2C are cross-sectional views illustrating a method of manufacturing a cylindrical capacitor according to another embodiment of the present invention.

Referring to FIG. 2A, an insulating film 22 is formed on the semiconductor substrate 20 provided with the junction region 21. In this case, the insulating film 22 is formed of a doped oxide film, such as a BoroPhospho Silicate Glass (BPSG) film, a BSG film, and a PSG film, or an undoped oxide film such as a thermal oxide film or HTO. The insulating layer 22 is etched to expose a part of the junction region 21 to form a contact hole, and the P ion is doped in-situ on the insulating layer 22 to be filled in the contact hole. A doped amorphous silicon film 23 is formed. At this time, the first doped amorphous polysilicon film 23 is PH ₃ gas diluted with silicon source gas such as SiH ₄ or Si ₂ H ₆ and inert gas such as N ₂ and He, or PH ₃ diluted with silicon gas. The gas is used as an impurity source gas to form at a temperature of about 530 ° C. or less.

Then, the core insulating film 24 is deposited on the first doped amorphous silicon film 23 to a thickness of 4,000 Å or more, and then the core insulating film 24 and the first doped amorphous silicon film ( 23) to define the capacitor region. Then, the second doped amorphous silicon film is deposited on the entire surface of the substrate under the same conditions as the first doped amorphous silicon film 23, and then etched to form the first doped amorphous silicon film 23 and the core insulating film 24. A spacer 25 made of a second doped amorphous silicon film is formed on both sidewalls. At this time, the etching process is performed using a gas containing a hydrocarbon, such as CHF ₃ gas. Accordingly, as shown in FIG. 2A, contaminants in the form of Si-C bonds are generated on the surface of the spacer 25.

Referring to FIG. 2B, the core insulating film 24 is selectively removed, and an O ₂ plasma treatment is performed to form a CO ₂ bond to remove contaminants. In this case, the O ₂ plasma process may be performed by applying RF (Radio Frequency) power to the semiconductor substrate to directly generate plasma or indirectly applying plasma at high power generated to the substrate. In addition, the O ₂ plasma treatment may be performed using only O ₂ gas, or may be performed by mixing with another gas that does not contain carbon such as N ₂ gas, and may be performed before removing the core insulating film 24. The resulting substrate is then etched with an oxide etch solution to remove the oxide film that may form on the surface.

Then, as shown in FIG. 2C, the HSG thin film 26 is formed on the surface of the first doped amorphous silicon film 23 and the spacer 25 by a selective HSG forming method, thereby storing the storage electrode 200 of the cylindrical capacitor. ). That is, the first doped amorphous silicon film using SiH ₄ gas or Si ₂ H ₆ gas as the source gas in a vacuum or high vacuum state using a single wafer type or batch wafer type equipment. A seed is formed on the surfaces of the 23 and the spacers 25 and annealing is performed to surface-move silicon atoms around the seeds, thereby forming the HSG thin film 26 on those surfaces. For example, in a high vacuum state, the pressure in the chamber is 10 ^-4 Torr or less and annealing is performed at a temperature equal to or higher than the temperature at the time of seed formation.

In addition, unlike the above embodiment, an undoped amorphous silicon film may be used in place of the doped amorphous silicon film, or a doped amorphous or polysilicon film covered with the undoped amorphous silicon film may be used. In this case, after the selective HSG thin film is formed, doping is carried out at a high temperature using a gas containing impurities, or the doping is carried out by exciting the impurities with plasma to contain insufficient impurities.

In addition, the O ₂ plasma treatment as described above can be removed during the semiconductor manufacturing process of etching with an etching gas containing a hydrocarbon can remove the carbon-based impurities.

According to the present invention described above, after the etching process using the etching gas containing a hydrocarbon, the contaminants of the Si-C bond form present on the surface of the amorphous silicon film is removed by O ₂ plasma treatment, and then formed on the surface of the amorphous silicon film. The HSG thin film can be easily formed to have a desired surface area.

Therefore, the capacitor capacity corresponding to high integration can be ensured.

In addition, this invention is not limited to the said Example, It can variously deform and implement within the range which does not deviate from the technical summary of this invention.

Claims (10)

In the method of manufacturing a capacitor of a semiconductor device comprising a hemispherical grain polysilicon thin film, Forming an amorphous silicon film doped as a material for a storage electrode on the semiconductor substrate; Etching the doped amorphous silicon film in the form of a predetermined storage electrode; Removing contaminants present on the surface of the doped amorphous silicon film by performing O ₂ plasma treatment on the surface of the etched doped amorphous silicon film; And, Forming a hemispherical grain polysilicon thin film on the doped amorphous silicon film surface to form a storage electrode. The method of claim 1, wherein the etching of the doped amorphous silicon film is performed by using a gas containing hydrocarbon. The method of claim 2, wherein the gas is CHF ₃ . The method of claim 1, wherein the O ₂ plasma treatment is performed by directly applying RF power to the substrate to generate a plasma. The method of claim 1, wherein the O ₂ plasma process is performed by indirectly applying a high power generated plasma to the substrate. The method of claim 1, wherein the O ₂ plasma process is performed using only O ₂ gas. The method of manufacturing a capacitor of a semiconductor device according to claim 1, wherein the O ₂ plasma treatment is performed using a mixed gas of O ₂ gas and another gas not containing carbon. The semi-spherical grain polysilicon thin film of claim 1, wherein the semi-spherical grain polysilicon thin film is formed by annealing after forming a seed on the doped amorphous polysilicon layer using SiH ₄ gas or Si ₂ H ₆ gas as the source gas. A method for manufacturing a capacitor of a semiconductor device, characterized in that it proceeds using the formation method. 9. The method of claim 8, wherein the hemispherical grain polysilicon thin film is formed using sheet-fed or group wafer type equipment. 10. The method of claim 8 or 9, wherein the annealing is performed at a pressure equal to or lower than 10 ^-4 Torr and at a temperature equal to or higher than the temperature at the time of seed formation.