KR100705400B1 - Method of performing electric wiring in semiconductor process - Google Patents

Abstract

A method of forming a wiring in a semiconductor device is disclosed, which prevents process defects caused by diffusion of a conductive material and reaction with a blocking film. A first insulating film having a first conductor pattern made of a hole or trench in which a conductive material is embedded is formed. A blocking film made of a silicon oxynitride film having oxygen and silicon of 1: 1.7 or less is formed on the first insulating film. A second insulating film is formed on the blocking film. Predetermined portions of the first insulating layer and the blocking layer are sequentially etched to form contact holes exposing a portion of the upper surface of the first conductor pattern. A metal barrier film is continuously formed in the contact hole and on an upper surface of the second insulating film. The conductive material is deposited while the contact hole in which the metal barrier film is formed is buried. At this time, since the blocking film having the composition is suppressed from reacting with the conductive material, it is possible to prevent the blocking film from being denatured into a conductor, thereby minimizing process defects in forming the wiring.

Description

Method of performing electric wiring in semiconductor process

1 is a cross-sectional view showing a defect caused by the reaction between aluminum and the low film.

2A to 2F are cross-sectional views illustrating a wiring forming method of a semiconductor device in accordance with an embodiment of the present invention.

3 is a graph showing conditions for forming a blocking film in which reaction with aluminum is suppressed.

FIG. 4 is a cross-sectional view showing a method for confirming whether or not to react with aluminum with respect to a SiON film formed according to each condition of FIG. 3.

FIG. 5 is a graphical representation of voltage versus current as a result of performing the method of FIG. 4.

6 is a graph showing the composition (atomic%) of the SiON film formed according to each condition.

FIG. 7 is a graph showing a result of manufacturing a semiconductor device including a blocking film formed under reaction conditions and unreacted conditions and testing the semiconductor device. FIG.

<Explanation of symbols for the main parts of the drawings>

20 semiconductor substrate 22 first insulating film                 

24: conductor pattern 26, 26a: blocking film

28, 28a: second insulating film 29: contact hole

30: metal barrier film 32: metal film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring forming method of a semiconductor device, and more particularly, to a wiring forming method of a semiconductor device including a blocking film for forming a contact hole.

In recent years, with the rapid spread of information media such as computers, semiconductor devices are also rapidly developing. In terms of its function, the semiconductor device is required to operate at a high speed and to have a large storage capacity. In response to such demands, manufacturing techniques have been developed for semiconductor devices to improve the degree of integration, reliability, and response speed. Among the manufacturing techniques, the demand for a technique for forming an electrical wiring is also becoming more stringent.

In recent years, the width of each conductor pattern and the distances between the conductor patterns for forming electrical wiring in semiconductor devices have become smaller. Accordingly, the size of the contact hole for connecting the upper conductor pattern and the lower conductor pattern is gradually reduced, and the depth thereof is also deepened, making it difficult to form the contact hole at the correct position.                         

A method of forming a wiring of a semiconductor device having the contact hole will be briefly described.

First, a first insulating film having a plurality of conductor patterns made of holes or trenches in which a conductive material is embedded is formed. Subsequently, a blocking film made of a silicon nitride film or a silicon oxynitride film is formed on the first insulating film. The blocking film is a film for making contact to an accurate position when forming a contact hole in a subsequent process.

A second insulating film is formed on the blocking film. Subsequently, predetermined portions of the second insulating layer and the blocking layer are sequentially etched to form a contact hole exposing a portion of the upper surface of the conductor pattern. The contact hole is formed to expose an upper portion of a plurality of conductor patterns set among the plurality of conductor patterns.

 Subsequently, a conductive material such as aluminum is embedded in the contact hole to form a wiring of the semiconductor device. The aluminum is a conductive material that is widely used for wiring of the semiconductor device which is most widely used because of low contact resistance and easy process progression.

However, when performing the above process, aluminum buried under the side of the contact hole diffuses into the blocking film and reacts with silicon, thereby frequently causing a defect of deforming the blocking film into a conductor.

1 is a cross-sectional view showing that the failure described above has occurred.

As shown in the drawing, when the stopper film 10 is denatured to the conductor 10a, the conductor patterns 12 to be insulated and a bridge are generated, so that current flows in an unwanted path. As a result, a stand-by current fail and a function fail of the semiconductor device may occur.

In order to prevent the diffusion of aluminum, a metal barrier layer is first formed on the inside of the contact hole and on the second insulating layer before depositing the aluminum. However, when the step coverage of the metal barrier film is not good, the thickness of the metal barrier film becomes thin at the lower side of the contact hole, and the aluminum is easily diffused through the interface of the metal barrier film. Therefore, even if the metal barrier film is formed, the defect cannot be completely prevented.

Accordingly, it is an object of the present invention to provide a method for forming a wiring in a semiconductor device which prevents process defects caused by diffusion of a conductive material and reaction with a blocking film.

In order to achieve the above object, the present invention forms a first insulating film having a first conductor pattern made of a hole or a trench in which a conductive material is embedded. A blocking film made of a silicon oxynitride film having oxygen and silicon of 1: 1.7 or less is formed on the first insulating film. A second insulating film is formed on the blocking film. Predetermined portions of the first insulating layer and the blocking layer are sequentially etched to form contact holes exposing a portion of the upper surface of the first conductor pattern. A metal barrier film is continuously formed in the contact hole and on an upper surface of the second insulating film. The conductive material is deposited while the contact hole in which the metal barrier film is formed is buried.

The conductive material deposited while buried in the contact hole includes aluminum.

As described above, when the blocking film is formed of a silicon oxynitride film having oxygen and silicon of 1: 1.7 or less, the reaction between the aluminum and the blocking film is suppressed even when a conductive material such as aluminum diffuses into the blocking film in a subsequent process. do. Therefore, the blocking film can be prevented from reacting with the aluminum to prevent the blocking film from being denatured into a conductor, thereby minimizing process defects during wiring formation.

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

2A to 2F are cross-sectional views illustrating a wiring forming method of a semiconductor device in accordance with an embodiment of the present invention.

Referring to FIG. 2A, a first insulating layer 22 having a plurality of conductor patterns 24 formed of holes or trenches in which a conductive material is embedded is formed on the semiconductor substrate 20. That is, upper surfaces of the plurality of conductor patterns 24 are exposed at predetermined portions of the upper surface of the first insulating layer 22.

Specifically, an insulating film is formed on a semiconductor substrate, and then a hole or a trench is formed in a portion where the conductor pattern 24 is to be formed on the insulating film. Subsequently, a conductive material is embedded in the hole or trench. The conductive material is etched by an etch back or chemical mechanical polishing (CMP) method to form a first insulating layer 22 through which the conductor pattern 24 is exposed on the upper surface. .

Alternatively, a conductive material is deposited and patterned on a semiconductor substrate on which the insulating film is formed to form a conductor pattern 24, and an insulating film is formed on the conductor pattern 24. The insulating layer may be etched back by etching back or chemical mechanical polishing (CMP) to form a first insulating layer 22 on which the conductor pattern 24 is exposed. have.

Referring to FIG. 2B, a blocking layer 26 formed of a silicon oxynitride film (hereinafter referred to as a SiON film) having oxygen and silicon of 1: 1.7 or less is formed on the first insulating film 22. The blocking layer 26 informs an etching end point during an etching process for forming a contact hole partially exposing the conductor pattern 24 by a subsequent process. By forming the stop layer 26, excessive etching is not performed on an unwanted portion when a photo misalignment is formed to form a subsequent contact hole. As a result, the photo misalignment margin increases, and a small contact hole can be easily formed.

The stop layer 26 made of a SiON film having oxygen and silicon of 1: 1.7 or less does not react with a metal material (for example, aluminum) during the subsequent process. The stop layer 26 is formed by PE-CVD using SiH ₄ , N ₂ O, and NH ₃ gas as a reaction gas. The ratio of oxygen and silicon in the SiON film formed by adjusting the flow rate of the SiH ₄ and N ₂ O gas in the reaction gas can be adjusted. This will be described later.

Referring to FIG. 2C, a second insulating film 28 made of an oxide is formed on the blocking film 26.

Referring to FIG. 2D, a predetermined portion of the first insulating layer 22 and the blocking layer 26 is continuously etched to form a contact hole 29 exposing a portion of the upper surface of the conductor pattern 24. . The contact hole 29 is formed to expose an upper portion of a plurality of conductor patterns 24 set among the plurality of conductor patterns 24.

Referring to FIG. 2E, the metal barrier layer 30 is continuously formed in the contact hole 29 and the upper surface of the second insulating layer 28a. The metal barrier film 30 is formed to prevent diffusion of the conductive material deposited in a subsequent process. For example, the metal barrier film 30 may be formed of a composite film of Ti / TiN.

Referring to FIG. 2F, a conductive material is deposited while the contact hole 29 in which the metal barrier film 30 is formed is deposited to form a metal film 32. The conductive material comprises aluminum.

Specifically, aluminum is deposited by physical vapor deposition (PVD) or chemical vapor deposition (CVD). Thereafter, heat treatment is performed at a temperature of 400 to 600 ° C. to reflow the aluminum to form a metal film. However, when the heat treatment is performed, the aluminum diffuses through the interface of the metal barrier film 30 having poor step coverage on the lower side of the contact hole 29 to the SiON film, which is the blocking film 26a. However, since the SiON film has a ratio of Si and oxygen of 1: 1.7 or less, the reaction with aluminum diffused is suppressed, and thus the SiON film is not denatured into a conductor.

In detail, as the aluminum diffuses into the SiON film, which is the blocking film 26, reaction with Si in the SiON film is continuously performed to denature the SiON film into a conductor. One method for preventing this, the Si and to which the oxygen and the aluminum react first, prior to the reaction with aluminum is carried Al ₂ O _3, by forming a film, the Al ₂ O by the _third film wherein the aluminum is no longer It can be prevented from spreading. Therefore, the SiON film should be formed so that the aluminum and the oxygen can react first, and satisfying this is a SiON film having the oxygen and silicon of 1: 1.7 or less as described above. The SiON film having the above composition can be formed by appropriately adjusting the ratio of Si and oxygen provided at the time of forming the SiON film.

The method of obtaining the above results and various experiments and data for demonstrating the same will be described below.

3 is a graph showing conditions for forming a blocking film in which reaction with aluminum is suppressed.

The SiON film used as the blocking film 26 is formed by plasma-enhanced CVD (PE-CVD) using a mixed gas containing SiH ₄ , N ₂ O and NH ₃ gas. At this time, the SiON is formed while changing the conditions of the flow rate and the RF power of each gas for forming the SiON film. Subsequently, when aluminum is deposited on each of the SiON films, the reaction may occur with aluminum, or the reaction may not occur, depending on the conditions for forming the SiON film. At this time, it can be seen that the dominant condition under which the reaction occurs with the aluminum is the flow rate of the SiH ₄ gas and the N ₂ O gas.

Therefore, the NH 3 gas and the RF power are fixed, and the reaction with aluminum is shown according to the flow rate of the SiH ₄ and N ₂ O gas. Specifically, 100 W of RF power was applied and NH ₃ gas provided 150 sccm. In addition, the flow rates of the SiH ₄ gas and the N ₂ O gas were increased, respectively.

3 is a graph of statistically analyzing the experimental results after performing representative experiments under several conditions while increasing the flow rates of the SiH ₄ gas and the N ₂ O gas forming the SiON film, respectively. As a result, a region (a) showing conditions for forming a SiON film that did not react with aluminum was obtained. It was also easy to react with aluminum when increasing the flow rate of SiH ₄ gas and reducing the N ₂ O gas. That is, the reaction tends to occur toward the area indicated by the arrow.

FIG. 4 is a cross-sectional view showing a method for confirming whether or not to react with aluminum with respect to a SiON film formed according to each condition of FIG. 3.

3 shows the results of analysis through several representative experiments, an experiment to verify the results is required. Therefore, in the experiment of FIG. 4, the SiON film was formed under the respective conditions corresponding to the reaction region and the unreaction region shown in FIG. 3, and then the reaction with aluminum was confirmed.

Each condition is specifically shown in Table 1 below. In Table 1, # 1, # 2 and # 5 are the conditions under which the reaction occurs with aluminum, and # 3 and # 4 are the conditions under which the reaction with aluminum does not occur. The conditions of # 1 to # 5 correspond to portions indicated by dots in FIG. 3.

In order to confirm the reaction between the SiON film formed under the conditions shown in Table 1 and the aluminum, impurities are doped on the entire surface of the semiconductor substrate 40 on which the pattern is not formed (40a).

SiH ₄ (sccm) N ₂ O (sccm) NH ₃ (sccm) RF power #One 80 150 150 100 W #2 80 250 150 100 W # 3 80 550 150 100 W #4 130 550 150 100 W # 5 180 550 150 100 W

Subsequently, about 100 microseconds of SiON film patterns 42 were formed under the conditions shown in Table 1, and metal film patterns 44 formed of aluminum were sequentially formed on the SiON film patterns 42. And 400 to 600 ℃ heat treatment was performed. Then, a voltage was applied to the silicon substrate and the metal film pattern doped with impurities (46), and an ammeter 48 was connected to measure the current flowing between both ends.

When the current is measured by the above-described method, since the silicon substrate 40 doped with the impurity and the metal film pattern 44 are insulated by the SiON film 42, the current should hardly flow. However, if a current flows between both ends, it can be seen that the SiON film 42 reacts with aluminum and is modified into a conductor.

FIG. 5 is a graphical representation of voltage versus current as a result of performing the method of FIG. 4.

As shown in the figure, the current was measured and graphed, respectively, while the voltage was sequentially increased from 0 to 1V. In this case, when the SiON film 42 is formed under the conditions of # 1, # 2, and # 5 corresponding to the reaction region in FIG. 3, the SiON film ( Compared with the case of forming 42), the current flows much more. The results indicate that the reaction and unreacted regions in FIG. 3 are reliable.

6 is a graph showing the composition (atomic%) of the SiON film formed according to each condition.

The conditions for forming the SiON film 42 are the same as those shown in Table 1, and the silicon (Si), oxygen (O), nitrogen ( N) The percentages of atoms are shown in bar graphs. In addition, the Si / O value was shown by the line graph.

Referring to FIG. 6, it can be seen that the reaction with aluminum occurs more preferably as the Si / O value increases, and the SiON film 42 is formed so that the Si / O value has a value of at least 1.7 or less. have.

FIG. 7 is a graph showing a result of manufacturing a semiconductor device including a blocking film formed under reaction conditions and unreacted conditions and testing the semiconductor device. FIG.

Referring to FIG. 7, the yield was about 12% and the stand-by current fail was about 70% when the blocking film was formed under the reaction with aluminum. On the other hand, when the blocking film was formed under conditions that do not react with aluminum, the yield increased to about 65%, and the standby current defect was reduced to about 25%. That is, the blocking film made of the SiON film is formed so that the Si / O in the blocking film has a value of 1.7 or less, thereby improving the yield and reducing the standby current defect.

As described above, according to the present invention, the yield of the semiconductor device can be improved by forming a blocking film that does not react with the metal material buried in the contact hole when the electrical wiring is formed.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified without departing from the spirit and scope of the invention described in the claims below. And can be changed.

Claims (5)

 Forming a first insulating film having a first conductor pattern made of a hole or trench in which a conductive material is embedded; Forming a stopper film formed of a silicon oxynitride film on which oxygen and silicon are formed in an amount of 1: 1.7 or less on the first insulating film; Forming a second insulating film on the blocking film; Continuously etching predetermined portions of the second insulating layer and the blocking layer to form a contact hole exposing a portion of an upper surface of the first conductor pattern; Continuously forming a metal barrier film in the contact hole and on an upper surface of the second insulating film; Depositing a conductive material including aluminum while burying a contact hole in which the metal barrier film is formed; And And heat-treating the conductive material. 2. The method of forming a semiconductor device according to claim 1, wherein the barrier metal film is formed of a mixed film of Ti / TiN. delete The method of claim 1, wherein the deposition of the aluminum is performed by physical vapor deposition (PVD) or chemical vapor deposition (CVD). The method of claim 1, wherein the heat treatment is performed at a temperature of 400 to 600 ° C. 7.

Images