KR20060006394A - Method for forming capacitor of semiconductor device - Google Patents

Abstract

The present invention discloses a method for forming a capacitor of a semiconductor device which can prevent the capacitance of the capacitor from being reduced, thereby improving the yield and reliability of the device. The disclosed method includes providing a semiconductor substrate having a conductive plug; Sequentially forming a sacrificial oxide film, an etching barrier film, and a hard mask film on the substrate; Selectively etching the hard mask layer, the etching barrier layer and the sacrificial oxide layer to form a contact hole exposing the conductive plug; Removing the hard mask layer on the etch barrier layer; Forming a polysilicon film for a storage node electrode on the resultant surface; Filling the contact hole structure by applying a photoresist film on the polysilicon film; Etching back the polysilicon layer until the etch barrier layer is exposed to form a cylindrical storage node electrode; Removing the remaining photoresist film; Forming an HSG on a surface of the storage node electrode; And sequentially forming a dielectric film and a conductive film for plate node electrodes on the resultant product.

Description

METHODS FOR FORMING CAPACITOR OF SEMICONDUCTOR DEVICE

1A to 1D are cross-sectional views of respective processes for explaining a method of forming a capacitor of a semiconductor device according to the related art.

2A to 2D are cross-sectional views of respective processes for explaining a method of forming a capacitor of a semiconductor device according to an embodiment of the present invention.

Explanation of symbols on main parts of drawing

30 semiconductor substrate 31 interlayer insulating film

32: first contact hole 33: conductive plug

34: sacrificial oxide film 35: etching barrier film

36: hard mask film 37: the second contact hole

38 polysilicon film for storage node electrode

39: photosensitive film 38a: storage node electrode

38b: HSG 40: dielectric film

41: conductive film for plate node electrode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for forming a capacitor of a semiconductor device for preventing the capacitance of the capacitor from being reduced and improving the yield and reliability of the device.

As the demand for semiconductor memory devices has soared, various techniques for obtaining high capacity capacitors have been proposed. The capacitor has a structure in which a dielectric film is interposed between a lower electrode and an upper electrode, called a storage node and a plate node, respectively, and the capacitance thereof is the surface area of the electrode, in particular, the surface area of the lower electrode and the dielectric constant of the dielectric film. Proportional to and inversely proportional to the distance between the electrodes.

Therefore, in order to obtain a high capacity capacitor, it is necessary to use a dielectric film having a high dielectric constant, enlarge the surface area of the lower electrode, or reduce the distance between the electrodes.

However, there is a limitation in reducing the distance between the electrodes, that is, the thickness of the dielectric film. As a method of increasing the capacity of the capacitor, a dielectric film having a high dielectric constant or a method of increasing the surface area of the electrode is preferable. .

In the current technology trend, as the material of the dielectric film, an NO film is applied to an existing ONO film, and further, efforts are being made to use a high dielectric constant film. As the structure of the capacitor lower electrode, a cylinder structure which can secure a large electrode area in a relatively simple process is mainly used. Furthermore, HSG (hemi-spherical silicon grain) is formed on the surface of the lower electrode to improve the electrode surface area. Maximizing techniques are becoming commonplace.

1A to 1D are cross-sectional views illustrating processes of forming a capacitor of a semiconductor device according to the related art, and a brief description of the method of forming a capacitor of a semiconductor device according to the related art will be described below.

In a conventional method of forming a capacitor of a semiconductor device, as shown in FIG. 1A, an interlayer insulating film 11 is formed on a semiconductor substrate 10 having a predetermined substructure (not shown), and then the interlayer insulating film ( 11) is selectively etched to form a first contact hole 12 exposing a predetermined portion of the substrate 10. Subsequently, the first contact hole 12 is filled with a conductive film to form a conductive plug 13.

Next, a sacrificial oxide film 14 and a hard mask film 15 are sequentially formed on the interlayer insulating film 11 including the conductive plug 13. Herein, a tetraethyl ortho silicate (TEOS) film is used as the sacrificial oxide film 14, and a polysilicon film is used as the hard mask film 15.

Next, as shown in FIG. 1B, the hard mask layer 15 and the sacrificial oxide layer 14 are selectively etched to form a second contact hole 16 exposing the conductive plug 13.

Subsequently, as shown in FIG. 1C, after the hard mask layer on the sacrificial oxide layer 14 is etched away and removed, a polysilicon layer 17 for a storage node electrode is formed on the resultant surface.

Then, the photoresist film 18 is coated on the polysilicon film 17 to fill the structure of the second contact hole 16. In this case, the photoresist layer 18 serves to protect the polysilicon layer 17 of the bottom portion of the second contact hole 16 during the etch back process of the polysilicon layer for the storage node electrode to be performed later.

Thereafter, as illustrated in FIG. 1D, the polysilicon layer is etched back until the sacrificial oxide layer 14 is exposed to form a cylindrical storage node electrode 17a. Subsequently, after the remaining photoresist film is removed, the HSG 17b is formed on the surface of the storage node electrode 17a to increase the surface area of the storage node electrode 17a.

Then, after forming the NO film as the dielectric film 19 on the resultant, the conductive film 20 for plate node electrodes is formed on the NO film. Here, the NO film is formed by sequentially performing a nitride film deposition process and an oxidation process.

However, in the related art, when the hard mask layer on the sacrificial oxide layer is etched back, a portion of the upper portion of the sacrificial oxide layer is lost, and the height of the storage node electrode formed thereafter is lowered, thereby reducing the capacity of the capacitor.

In addition, according to the current technology trend, since the deposition thickness of the nitride film constituting the NO film as the dielectric film becomes thin, some nitride films are weakly deposited on the upper surface of the sacrificial oxide film during the nitride film deposition process for forming the NO film. In the oxidation process performed after the nitride film deposition process, O ₂ passes through the nitride film weak deposition region to partially oxidize the upper portion of the storage node electrode. As such, when the upper portion of the storage node electrode is partially oxidized, the height of the storage node electrode is lowered, thereby reducing the capacity of the capacitor and causing a problem that the yield and reliability of the device are lowered.

Accordingly, the present invention has been made to solve the above problems, and during the hard mask film etch back process on the sacrificial oxide film, the sacrificial oxide film can be prevented from being partially lost, and the oxidation for forming the NO film is performed. By preventing the upper portion of the storage node electrode from being oxidized by O ₂ in the process, it is possible to prevent the height of the storage node electrode from being lowered, and further, to form a capacitor of the semiconductor device, which can improve the yield and reliability of the device. The purpose is to provide a method.

Capacitor forming method of a semiconductor device of the present invention for achieving the above object comprises the steps of providing a semiconductor substrate provided with a conductive plug; Sequentially forming a sacrificial oxide film, an etching barrier film, and a hard mask film on the substrate; Selectively etching the hard mask layer, the etching barrier layer and the sacrificial oxide layer to form a contact hole exposing the conductive plug; Removing the hard mask layer on the etch barrier layer; Forming a polysilicon film for a storage node electrode on the resultant surface; Filling the contact hole structure by applying a photoresist film on the polysilicon film; Etching back the polysilicon layer until the etch barrier layer is exposed to form a cylindrical storage node electrode; Removing the remaining photoresist film; Forming an HSG on a surface of the storage node electrode; And sequentially forming a dielectric film and a conductive film for plate node electrodes on the resultant product.

Here, the etching barrier film is formed to a thickness of 100 ~ 150Å by using a nitride film.

(Example)

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2A to 2D are cross-sectional views of respective processes for explaining a method of forming a capacitor of a semiconductor device according to an embodiment of the present invention.

In the method of forming a capacitor of a semiconductor device according to an embodiment of the present invention, as shown in FIG. 2A, an interlayer insulating film 31 is formed on a semiconductor substrate 30 having a predetermined substructure (not shown). The first interlayer insulating layer 31 is selectively etched to form a first contact hole 32 exposing a predetermined portion of the substrate 30. Subsequently, the first contact hole 32 is filled with a conductive film to form a conductive plug 33.

Next, a sacrificial oxide film 34, an etch barrier film 35, and a hard mask film 36 are sequentially formed on the interlayer insulating film 31 including the conductive plug 33. Here, a TEOS film is used as the sacrificial oxide film 34 and a polysilicon film is used as the hard mask film 36. In addition, the etch barrier film 35 is formed using a nitride film, but is formed to a thickness of 100 ~ 150 백 considering the thickness lost during the subsequent hard mask film etch back process.                     

Next, as shown in FIG. 2B, the hard contact layer 36, the etching barrier layer 35, and the sacrificial oxide layer 34 are selectively etched to expose the conductive plug 33. 37).

Subsequently, as shown in FIG. 2C, the hard mask layer on the etch barrier layer 35 is etched back and removed, and then a polysilicon layer 38 for a storage node electrode is formed on the resultant surface. In this case, the etching barrier layer 35 serves to prevent the sacrificial oxide layer 34 under the etching barrier layer 35 from being lost during the etch back process of the hard mask layer. Accordingly, it is possible to prevent the height of the storage node electrode to be subsequently formed.

Then, the photosensitive film 39 is coated on the polysilicon film 38 to fill the structure of the second contact hole 37. In this case, the photoresist layer 39 serves to protect the polysilicon layer 38 of the bottom portion of the second contact hole 37 during the etch back process of the polysilicon layer for the storage node electrode to be performed later.

Thereafter, as illustrated in FIG. 2D, the polysilicon layer is etched back until the etch barrier layer 35 is exposed to form a cylindrical storage node electrode 38a. Subsequently, after the remaining photoresist film is removed, an HSG 38b is formed on the surface of the storage node electrode 38a to increase the surface area of the storage node electrode 38a.

Thereafter, an NO film is formed as the dielectric film 40 on the resultant, and then a conductive film 41 for plate node electrodes is formed on the NO film. Here, the NO film is formed by sequentially performing a nitride film deposition process and an oxidation process.

On the other hand, the etching barrier film 35 serves to prevent the O ₂ in the oxidation process performed after the nitride film deposition process for forming the NO film to oxidize the upper portion of the storage node electrode 38a. As a result, the height of the storage node electrode 38a may be prevented from being lowered due to the application of the etching barrier layer 35.

As described above, the present invention further forms an etch barrier film between the sacrificial oxide film and the hard mask film, thereby preventing the sacrificial oxide film from being lost by the etch barrier film during the etchback process of the hard mask film, thereby to be formed later. The height of the storage node electrode can be prevented from being lowered. In addition, even when O ₂ in the oxidation process for forming an NO film passes through the nitride film vulnerable deposition area, the etch barrier film no longer penetrates to the lower portion, thereby preventing oxidation of the storage node electrode by the O ₂ . can do. As a result, the present invention can maintain the height of the storage node electrode to prevent the reduction of the capacitor capacity, and can improve the yield and reliability of the device.

Claims (2)

Providing a semiconductor substrate provided with a conductive plug; Sequentially forming a sacrificial oxide film, an etching barrier film, and a hard mask film on the substrate; Selectively etching the hard mask layer, the etching barrier layer and the sacrificial oxide layer to form a contact hole exposing the conductive plug; Removing the hard mask layer on the etch barrier layer; Forming a polysilicon film for a storage node electrode on the resultant surface; Filling the contact hole structure by applying a photoresist film on the polysilicon film; Etching back the polysilicon layer until the etch barrier layer is exposed to form a cylindrical storage node electrode; Removing the remaining photoresist film; Forming an HSG on a surface of the storage node electrode; And And sequentially forming a dielectric film and a conductive film for a plate node electrode on the resultant. The method of claim 1, wherein the etching barrier layer is formed to a thickness of about 100 to about 150 microns by using a nitride layer.

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