KR20030096669A - method for manufacturing gate in semiconductor memory device - Google Patents

Abstract

PURPOSE: A method for manufacturing a gate of a semiconductor memory device is provided to be capable of preventing a lower layer from being not etched due to the generation of bridge phenomenon at a photoresist layer. CONSTITUTION: After sequentially forming a polysilicon layer(100), a metal silicide layer(102), and a mask layer(104a), a photoresist layer(106) is coated at the upper portion of the mask layer. Then, a photoresist pattern is formed by sequentially carrying out an exposure and development process at the photoresist layer. A breakthrough process is carried out at the resultant structure by using an etchant having a low selectivity for the photoresist pattern. A main etching process is carried out at the mask layer by using the photoresist pattern as an etching mask.

Description

Method for manufacturing gate in semiconductor memory device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor memory device, and more particularly to a method of manufacturing a gate of a highly integrated transistor.

As the semiconductor memory device is highly integrated, the gate pattern of the transistor is also gradually reduced. As the gate area is reduced, the resistance of the gate electrode is increased to decrease the operation speed of the transistor. Therefore, in this field, the gate electrode is formed using a conductive material having a low resistance, thereby improving the operation speed of the transistor. Recently, as a low-resistance material for reducing the resistance of the gate electrode, a silicide film, which is a compound of a metal and silicon such as tungsten (W), titanium (Ti) or tantalum (Ta), is mainly used.

1A and 1B show a method of manufacturing a gate of a semiconductor device according to the conventional method.

Referring to FIG. 1A, a gate polysilicon layer 10 and a tungsten silicide layer 12 are sequentially formed on a semiconductor substrate (not shown) in which an active region and an inactive region are separated by an isolation layer. Here, a titanium silicide film or a tantalum silicide film may be formed in addition to the tungsten silicide film.

Subsequently, a mask film 14 for patterning the tungsten silicide film 12 is formed on the tungsten silicide film 12. In this case, the mask layer 14 is formed by depositing an insulating film such as PEOX, SiON, SiN, or the like. Then, the photoresist film is entirely coated on the semiconductor substrate on which the mask film 14 is formed, and then the photoresist pattern 16 as shown is formed using a reticle.

However, as the digital rule of the semiconductor memory device is reduced, the pitch between the photoresist patterns for etching the lower material layer decreases. It is formed in several places. Problems caused by such scumber bridges will be described with reference to FIG. 1B below.

Referring to FIG. 1B, the lower mask layer 14 is dry-etched using the photosensitive film pattern 16 having the scum bridge formed thereon as an etching mask. As an etchant for etching the mask layer 14, a gas composed of CHF 3, CF 4, Ar, and O 2 is used. An etchant composed of the gases is present between the photoresist patterns due to a high etching selectivity with respect to the photoresist layer 16. It is not possible to remove the scum bridge. As a result, the mask film in the region where no scum bridge is present is completely etched until the lower tungsten silicide film 12 is exposed. However, there is a problem in that a mask film such as indicated by reference numeral "B" is not etched in the region where the scum bridge is formed, that is, the region "A" of FIG. .

As such, when the mask layer is not etched, the mask layer may not function as an etching mask for patterning the lower tungsten silicide, resulting in the inability to form the gate electrode of the transistor.

Accordingly, an object of the present invention is to provide a method of manufacturing a gate of a semiconductor memory device that can solve the above-described conventional problems.

Another object of the present invention is to provide a method of manufacturing a gate of a semiconductor memory device that can solve the problem that the lower layer is unetched due to the scum bridge of the photosensitive layer.

In order to achieve the above object, in the present invention, forming a polysilicon film, a metal silicide film and a mask film to be patterned as an etching mask for etching the metal silicide film on top of the semiconductor substrate; Applying a photoresist layer on the mask layer, and then exposing and developing the photoresist layer to pattern the photoresist pattern for etching the mask layer; Performing a breakthrough step process for removing scum bridges between the photoresist patterns by using an etchant having a low etching selectivity with respect to the photoresist; And after performing the break-through step process, performing a main etching process of etching the mask layer using the photoresist pattern.

1A and 1B are cross-sectional views illustrating a method of manufacturing a gate of a semiconductor memory device according to a conventional method.

2A and 2C are cross-sectional views illustrating a method of manufacturing a gate of a semiconductor memory device according to an embodiment of the present invention.

Hereinafter, a method of manufacturing a gate of a semiconductor memory device according to an embodiment of the present invention will be described with reference to the accompanying drawings. Although shown in different figures, the same to similar layers are shown with the same reference numerals.

2A and 2C are cross-sectional views illustrating a method of manufacturing a gate of a semiconductor memory device according to an embodiment of the present invention.

First, referring to FIG. 2A, a gate polysilicon layer 100 and a tungsten silicide layer 102 are sequentially formed on a semiconductor substrate (not shown) in which an active region and an inactive region are separated by an isolation layer. Here, a titanium silicide film or a tantalum silicide film may be formed in addition to the tungsten silicide film.

Then, a mask film 104 for patterning the tungsten silicide film 102 as a gate electrode is deposited on the tungsten silicide film 102. Here, an insulating film such as PEOX, SiON, SiN, or the like may be used as the mask film 104. The entire photoresist film is applied over the semiconductor substrate on which the mask film 104 is formed, and then a plurality of photoresist patterns 106 are formed by applying a reticle, exposing and developing the photoresist film.

At this time, due to the limitations of the photo equipment, scum bridges are formed in several places between the photoresist patterns. For example, it is assumed that scum bridges (reference numeral “C”) are formed between the photoresist pattern 106a and the photoresist pattern 106b. lets do it.

Conventionally, by performing the etching process for patterning the mask film while the scum bridge is formed between the photosensitive film patterns, the mask film is not etched in the scum bridge area. Accordingly, in the present invention, after the scum-like bridge is completely removed, a subsequent mask film etching process is performed. A more detailed scum-like bridge removing method is described below with reference to FIG. 2B.

Referring to FIG. 2B, a breakthrough step process 108 using an etchant having a low etching selectivity with respect to the photosensitive film 106 is performed on the photosensitive film pattern 106 on which the scum-shaped bridge is formed. . By performing the breakthrough step process, scum bridges existing between the mask pattern 106a and the mask pattern 106b are completely removed.

At this time, as an etching etchant used in the break-through step process, a gas composed of CF 4, O 2 and Ar is used. In the breakthrough step, the CF4 gas maintains a flow rate of about 30-50 sccm (standard cubic centimeter per minute), O2 gas of about 9-20 sccm, and Ar gas of about 400-500 sccm. The chamber pressure is preferably maintained at about 150 to 175 mT, and the chamber power is maintained at about 300 to 600 W.

Referring to FIG. 2C, the main mask process 110 using the photosensitive film pattern 106 from which the scum bridge is completely removed by the breakthrough step process is performed to dry-etch the lower mask film. As a result of the dry etching process, a complete mask layer pattern 104a is formed in which the mask layer is not etched.

In the above description, the embodiments of the present invention have been described with reference to the drawings, for example. However, it will be apparent to those skilled in the art that the present invention may be variously modified or changed within the scope of the technical idea of the present invention. . For example, if the matters are different, the order of the processes and the film material or shape may be changed.

As described above, in the present invention, a breakthrough step using an etchant having a low etching selectivity for the photosensitive film is performed to remove scum bridges between the photosensitive film patterns serving as an etching mask for the lower layer. . As such, by performing the breakthrough step process before performing the main etching process for patterning the lower layer, it is possible to solve the problem that the lower layer is not etched due to the scum bridge.

Claims (6)

Sequentially forming a polysilicon film, a metal silicide film, and a mask film to be patterned as an etching mask for etching the metal silicide film on the semiconductor substrate; Applying a photoresist layer on the mask layer, and then exposing and developing the photoresist layer to pattern the photoresist pattern for etching the mask layer; Performing a breakthrough step process for removing scum bridges between the photoresist patterns by using an etchant having a low etching selectivity with respect to the photoresist; And performing a main etching process of etching the mask layer by using the photoresist pattern after performing the break-through step process. The method of claim 1, wherein the metal silicide layer is formed of one of a tungsten silicide layer, a titanium silicide layer, and a tantalum silicide layer. The method of claim 1, wherein the mask layer is formed of any one of PEOX, SiON, and SiN. The method of claim 1, wherein the etching etchant used in the breakthrough step is a mixed gas consisting of CF 4, O 2, and Ar. 5. The method of claim 4, wherein the flow rate of CF4 gas in the mixed gas is 30-50 sccm, the flow rate of O2 gas is 9-20 sccm, and the flow rate of Ar gas is 400-500 sccm. 6. The method of manufacturing a gate of a semiconductor memory device according to claim 5, wherein the pressure in the chamber where the breakthrough step is performed is 150 to 175 mT, and the power in the chamber is 300 to 600 W.