KR20010004932A - method of forming cylindrical capacitor of semiconductor device - Google Patents

Abstract

PURPOSE: A method for forming a cylinder-type capacitor of a semiconductor device is provided to prevent an electric short phenomenon of each MPS(metastable polysilicon) by forming MPS on only inner wall of a cylinder-type second polysilicon layer. CONSTITUTION: The first insulating layer(1) is deposited on a semiconductor substrate, and a contact hole(2) is formed by etching the first insulating layer. The contact hole is buried with the first polysilicon layer. A core oxide layer is deposited on the interfacial insulating layer, and a cylinder-shape core oxide layer is formed by an etching process using a photoresist pattern. The second insulating layer(5) having an etching selection different from that of the core oxide layer is deposited on the total structure as a thin thickness. Except the second insulating layer positioned on a sidewall of the core oxide layer, the residual insulating layer is removed. The second polysilicon layer(6) is deposited on the total structure, the total structure's surface is polished, thereby removing the second polysilicon layer(6) positioned to upper parts of the core oxide layer and the second insulating layer(5). The core oxide layer is only wet-etched, and thus the second polysilicon layer of a cylinder shape is formed. Outer wall of the second polysilicon layer(7) is enclosed by the second insulating layer. Metastable polysilicon(MPS) layer of an embossing shape is formed on an inner wall of the second polysilicon layer of a cylinder-shape.

Description

Method of forming cylindrical capacitor of semiconductor device

The present invention relates to a method of forming a cylindrical capacitor of a semiconductor device, and more particularly to a method of forming a capacitor having an embossed shape on the inner wall of the cylinder structure.

Recently, with the development of semiconductor manufacturing technology, the demand for memory devices has increased so that high capacitance is required in a small area.

The capacitance of the capacitor is proportional to the dielectric constant and area of the dielectric and inversely proportional to the thickness. However, as the device becomes more integrated, a method for maximizing the capacitor capacity is proposed by using an insulator having a high dielectric constant for the dielectric between the electrodes, a method of enlarging the electrode area, or reducing the thickness of the dielectric. It became. In order to provide high capacity for high integration of semiconductor memory devices, conventionally, SiO ₂ / Si ₃ N ₄ or Ta ₂ O ₅ is used as a dielectric, and the storage electrode is formed in a cylindrical structure as a method of expanding the electrode area. It was.

A method of manufacturing a conventional cylindrical capacitor is as follows. First, an interlayer insulating film is formed over the entire semiconductor substrate, and the interlayer insulating film is etched to form a contact hole for a capacitor. Then, a first polysilicon film is deposited on the interlayer insulating film to fill the contact hole with the first polysilicon. Subsequently, a core oxide film is deposited on the first polysilicon.

Then, the core oxide film is etched by using the ring-shaped photoresist pattern as an etching mask, thereby forming a core oxide film having a cylinder structure. Then, a second polysilicon film is deposited on the inner wall of the core oxide film. In order to increase the surface area of the capacitor, an embossed, metastable polysilicon (hereinafter referred to as MPS), which is a rugged structure, is deposited on the inner wall of the second polysilicon film.

Then, photoresist is applied on the entire resultant, and the inside of the cylinder structure is embedded with photoresist. Then, when the entire result is polished by the chemical mechanical polishing method, the predetermined thickness of the photoresist is removed and the core oxide film is also removed, thereby exposing the second polysilicon and the top of the MPS. By removing the photoresist inside the cylinder structure, a capacitor having a cylindrical structure and having an embossed shape is completed.

In the above-described conventional capacitor forming method, since the inner and outer walls of the cylindrical second polysilicon film are all exposed in the step of forming the MPS, the MPS is formed not only on the inner wall but also on the outer wall of the second polysilicon film. As a result, the distance between the outer walls of the second polysilicon film having a fine pattern interval is further narrowed due to the MPS, so that there is a high possibility that an electric short is generated between the MPSs.

The present invention has been made to solve the problems of the conventional capacitor formation method described above, MPS is formed only on the inner wall of the cylindrical second polysilicon film, it is possible to prevent the phenomenon that each MPS is electrically shorted It is an object to provide a method of forming a cylindrical capacitor of a semiconductor device.

1 to 7 are cross-sectional views sequentially showing a capacitor forming method according to the present invention.

Description of symbols for the main parts of the drawings

One ; 1st insulating film 2; Contact hole

3; 1st polysilicon film 4; Core oxide film

5; 2nd insulating film 6; Second polysilicon film

7; MPS

In order to achieve the above object, a method of forming a capacitor according to the present invention is as follows.

After depositing a first insulating film on the semiconductor substrate, the first insulating film is etched to form contact holes. After the core oxide film is deposited on the first insulating film, the core oxide film is etched using the ring-shaped photoresist pattern as an etching mask, and then the photoresist pattern is removed, thereby forming a cylindrical core oxide film. Then, the second insulating film having a different etching selectivity from the core oxide film is deposited thinly on the entire structure surface, and then the second insulating film portion on the surface of the core oxide film, the first polysilicon film and the first insulating film is removed to remove the core oxide film. The second oxide film remains only on the sidewalls.

After the second polysilicon film is deposited on the entire resultant surface, the core oxide film and the second polysilicon film portion on the top of the second insulating film are etched and removed. Subsequently, when only the core oxide film is wet-etched and removed, since the second insulating film different from the core oxide film and the etching selectivity is not removed, the outer wall of the cylindrical second polysilicon film is surrounded by the second insulating film.

Subsequently, an embossed metastable polysilicon film is deposited. Since the outer wall of the second polysilicon film is surrounded by the second insulating film, the metastable polysilicon film is deposited only on the inner wall of the second polysilicon film.

According to the above-described configuration of the present invention, if only the core oxide film is removed after the second insulating film is deposited before the deposition of the second polysilicon film, the outer wall of the second polysilicon film is surrounded by the second insulating film. Therefore, the MPS is not deposited on the second insulating film but only on the inner wall of the second polysilicon film, so that the case where each MPS is shorted is fundamentally prevented.

Best Mode for Carrying Out the Invention Preferred embodiments of the present invention will now be described based on the accompanying drawings.

1 to 7 are cross-sectional views sequentially showing a cylindrical capacitor according to the present invention in the order of manufacturing process.

First, as shown in FIG. 1, after depositing a first insulating film 1 on a semiconductor substrate (not shown), the first insulating film 1 is etched to form a contact hole 2. Then, after filling the contact hole 2 with the first polysilicon film 3, the core oxide film 4 is deposited on the entire resultant.

Next, as shown in FIG. 2, the core oxide film 4 exposing the first polysilicon film 3 by etching the core oxide film 4 by using a cylindrical photoresist pattern (not shown) as an etching mask. To form. Then, the second insulating film 5 proposed in the present invention is thinly deposited on the entire resultant surface to a thickness of 100 kPa or less. As the second insulating film 5, a material having a different etching selectivity from that of the core oxide film 4 is used.

Subsequently, as shown in FIG. 3, the entire resultant is etched, and the portion of the second insulating film 5 on the surface of the core oxide film 4 and the surface of the first insulating film 1 and the first polysilicon film 3 is removed. Remove Therefore, the second insulating film 5 is implemented in the form of a spacer that remains only on the sidewall of the core oxide film 4.

Then, the second polysilicon film 6 is deposited on the entire resultant product as shown in FIG. 4. Subsequently, referring to FIG. 5, after filling the inside of the cylinder structure with a peeling oxide film (not shown), the entire resultant surface is polished by chemical mechanical polishing to remove a certain thickness. Then, the second polysilicon film 6 on the upper end of the core oxide film 4 and the second insulating film 5 is removed, so that the upper ends of the core oxide film 4 and the second insulating film 5 are exposed.

Subsequently, the core oxide film 4 is wet-etched and removed as shown in FIG. 6. At this time, the etching selectivity of the core oxide film 4 and the second insulating film 5 is different from each other, so that the second insulating film 5 is not etched, and only the core oxide film 4 is etched and removed. Therefore, while the second polysilicon film 6 is formed in a cylindrical shape, its outer wall is surrounded by the second insulating film 5.

In such a state, when the MPS 7 having the embossed shape is deposited, the MPS 7 is not grown on the second insulating film 5 as shown in FIG. 7, and only the MPS 7 is formed on the inner wall of the second polysilicon film 6. ) Is deposited. Therefore, the MPS 7 is not deposited on the capacitor outer wall of each cylinder structure, and the short caused by the MPS 7 is prevented.

As described above, according to the present invention, the MPS is not formed on the cylindrical capacitor outer wall but only on the inner wall by causing the outer wall of the cylindrical second polysilicon film to be surrounded by the second insulating film. Therefore, a short phenomenon due to the MPS formed on the outer wall of the cylindrical capacitor is fundamentally prevented.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described claims, and the present invention is not limited to the scope of the present invention. Anyone with knowledge will be able to make various changes.

Claims (1)

Depositing a first insulating film on a semiconductor substrate, and then etching the first insulating film to form a contact hole; Filling the contact hole with first polysilicon; Depositing a core oxide film on the interlayer insulating film, and forming a cylindrical core oxide film by an etching process using a photoresist pattern; Thinly depositing a second insulating film having a different etching selectivity from the core oxide film on the entire resultant, and then removing the remaining second insulating film portions except for the second insulating film portion located on the sidewall of the core oxide film; Depositing a second polysilicon film on the whole resultant, and then polishing the entire resultant surface to remove the second polysilicon film on top of the core oxide film and the second insulating film; Wet etching only the core oxide film to form a cylindrical second polysilicon film surrounded by the second insulating film; And And forming an embossed metastable polysilicon film only on an inner wall of the cylindrical second polysilicon film.