KR100372818B1 - Method of forming gate for semiconductor device - Google Patents

Abstract

The present invention provides a method of forming a gate of a semiconductor device capable of suppressing oxidation of a metal while effectively oxidizing polysilicon during an oxidation process performed after etching for forming a gate.

A gate forming method of a semiconductor device according to the present invention is as follows. First, a gate oxide film is formed on a semiconductor substrate, and a polysilicon film, a diffusion barrier metal film, and a metal film are sequentially formed as a gate material on the gate oxide film. Then, a gate is formed by etching the metal film, the barrier metal film, and the polysilicon film, and the substrate on which the gate is formed is oxidized by wet oxidation to form oxide films on both surfaces of the polysilicon film, and at the same time damage the gate oxide film surface. To recover. In this embodiment, the wet oxidation is carried out at a low temperature of 70 to 100 ℃, preferably 80 to 90 ℃ using a chemical solution based on H ₂ SO ₄ .

Description

Method of forming gate for semiconductor device

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 gate of a semiconductor device having a laminated structure of a polysilicon film / barrier metal film / tungsten film.

In general, a polysilicon film is used as a gate material of a semiconductor device, and after patterning of the polysilicon film, in order to prevent etching damage, particularly damage to the gate oxide film, LDD (lightly) by dry oxidation in an O ₂ gas atmosphere doped drain) oxidation was carried out.

On the other hand, since the resistance of the gate acts as an important factor as the degree of integration of the semiconductor device increases, in the case of a semiconductor device having a design rule of 0.15 μm or less, the gate is made of polysilicon to improve the resistance characteristics of the gate. The film was formed in a laminate structure of a low resistance metal film such as a tungsten film. At this time, a barrier metal film for preventing diffusion between the tungsten film and the polysilicon film is formed through a titanium nitride film (TiN) or a tungsten nitride film (WN).

However, in the formation of the gate of the tungsten-polysilicon structure as described above, if LDD oxidation is performed to recover the etch damage after patterning of the gate, metals such as tungsten, TiN, and WN are severely oxidized, so that deformation of the gate is prevented. The problem that arises arises.

In order to solve this problem, recently, a selective oxidation process for selectively dry oxidizing a polysilicon film in a mixed gas atmosphere of O ₂ and H ₂ after etching to form a gate pattern has been proposed, but it is difficult to secure reproducibility. Difficult to apply to the actual process.

In addition, dry oxidation using the O ₂ gas or the mixed gas of O ₂ and H ₂ as described above generally proceeds at a relatively high temperature of 800 to 1,000 ℃, the characteristics of the device by the movement of impurities in the high temperature process There is a problem of deterioration.

Accordingly, the present invention is to solve the above-mentioned conventional problems, a method of forming a gate of a semiconductor device that can suppress the oxidation of the metal while effectively oxidizing the polysilicon during the oxidation process proceeds after etching for the formation of the gate. The purpose is to provide.

In addition, an object of the present invention is to provide a method for forming a gate of a semiconductor device that can prevent the deterioration of device characteristics due to impurity movement by proceeding the above oxidation process at a relatively low temperature.

1A to 1C are cross-sectional views illustrating a gate forming method of a semiconductor device in accordance with an embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

10 semiconductor substrate 11 gate oxide film

12 polysilicon film 13 barrier metal film

14: tungsten film 100: gate

15: photoresist film pattern

16: oxide film

In order to achieve the above object of the present invention, the gate forming method of a semiconductor device according to the present invention is as follows. First, a gate oxide film is formed on a semiconductor substrate, and a polysilicon film, a diffusion barrier metal film, and a metal film are sequentially formed as a gate material on the gate oxide film. Then, a gate is formed by etching the metal film, the barrier metal film, and the polysilicon film, and the gate-formed substrate is oxidized by wet oxidation by a low temperature process using a chemical solution based on H ₂ SO ₄ . The oxide film is formed on both surfaces of the film and the damage of the gate oxide film is repaired. In this embodiment, the wet oxidation is carried out at 70 to 100 ° C., preferably 80, using a chemical solution based on H ₂ SO ₄ . To low temperature of 90 ° C.

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 gate forming method of a semiconductor device in accordance with an embodiment of the present invention.

Referring to FIG. 1A, a gate oxide film 11 is formed on a semiconductor substrate 10, a doped polysilicon film 12 and a diffusion barrier metal layer 13 as a gate material on the gate oxide film 11. And the tungsten film 14 is sequentially formed as a low resistance metal film. Here, the barrier metal film 13 is formed of a titanium nitride film or a tungsten nitride film. In addition, a metal silicide film can be formed in place of the tungsten film 14. Here, the metal of the metal silicide film is one metal selected from the group consisting of cobalt, tungsten, and titanium. Then, the photoresist film pattern 15 for gate is formed on the tungsten film 14 by photolithography.

Then, the tungsten film 14, the barrier metal film 13, and the polysilicon film 12 are etched using the photoresist film pattern 15 as an etching mask, and as shown in FIG. 1B, the polysilicon film ( 12A), the barrier metal film 13A and the tungsten film 14 are formed with a stacked structure 100. Then, the photoresist film pattern 15 is removed by a known method.

Referring to FIG. 1C, in order to recover the etch damage, the structure of FIG. 1B is wet oxidation using a chemical solution based on H ₂ SO ₄ , and LDD oxidation at a relatively low temperature of 70 to 100 ° C., preferably 80 to 90 ° C. By proceeding, the oxide films 16 are formed on both side surfaces of the etched polysilicon film 12A, and the damage of the gate oxide film 11 is restored. That is, the chemical solution based on H ₂ SO ₄ has a characteristic of oxidizing the surface of the polysilicon film at a relatively low temperature. Therefore, in the present invention, instead of the conventional dry oxidation using O ₂ gas, wet oxidation is performed using a chemical solution based on H ₂ SO ₄ , such as the barrier metal film 13A and the tungsten film 13A. While suppressing the oxidation of the metal, the surface of the polysilicon film 12A can be oxidized and damage to the gate oxide film 11 can be recovered.

According to the present invention described above, after etching to form a gate formed of a laminated structure of a polysilicon film / barrier metal film / tungsten film, an oxidation process for recovering etching damage is performed at a relatively low temperature by wet oxidation based on H ₂ SO ₄ . By proceeding at, it is possible to easily oxidize the surface of the polysilicon film while restraining the oxidation of the metal, and to recover damage to the gate oxide film.

In addition, since wet oxidation is performed at a relatively low temperature, impurity migration can be prevented during the oxidation process, thereby improving the device characteristics.

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 (7)

Forming a gate oxide film on the semiconductor substrate; Sequentially forming a polysilicon film, a diffusion barrier metal film, and a metal film as a gate material on the gate oxide film; Etching the metal film, the barrier metal film, and the polysilicon film to form a gate; And The gate-formed substrate is oxidized by wet oxidation by a low temperature process using a chemical solution based on H ₂ SO ₄ to form oxide films on both surfaces of the polysilicon film and to recover damages on the gate oxide film surface. And forming the gate of the semiconductor device. delete The method of claim 1, wherein the wet oxidation is performed at a temperature of 70 to 100 ° C. 7. The method of claim 3, wherein the wet oxidation is performed at a temperature of 80 to 90 ° C. 5. The method of claim 1, wherein the barrier metal film is formed of a tungsten nitride film or a titanium nitride film. The method of claim 1, wherein the metal film is formed of a metal silicide film. 7. The method of claim 6, wherein the metal of the metal silicide film is one selected from the group consisting of cobalt, tungsten, and titanium.