JP2002353223A - Semiconductor device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device which has a simple structure and high reliability by using only a low dielectric constant film for an insulation film. SOLUTION: This manufacturing method comprises a process for forming the low dielectric constant film 2 on a semiconductor substrate 1 and forming wiring grooves 5 in the film 2, a process for forming a barrier metal 4 on the surface of the low dielectric constant film 2 and in the wiring grooves 5, a process for forming a copper wiring layer 6 so as to fill in the wiring grooves 5, a process for eliminating the copper wiring layer 6 on the barrier metal layer 4 except for the inside of the wiring grooves 5, and a process for removing needless barrier metals 4 on the low dielectric constant film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device in which a copper wiring layer is formed on a semiconductor substrate via an insulating film and a barrier metal, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Along with the high integration and miniaturization of semiconductor devices, finer wiring, smaller wiring pitch, and more multilayer wiring have been promoted, and the importance of multilayer wiring technology in the semiconductor device manufacturing process has increased. are doing. Conventionally, aluminum has been frequently used as a wiring material for a semiconductor device having a multilayer wiring structure. However, in recent design rules under the 0.25 μm rule, in order to suppress signal propagation delay, the wiring material was changed from aluminum to copper. Developed wiring processes are being developed. When copper is used for wiring, there is an advantage that both low resistance and high electromigration resistance can be achieved.

In a wiring process using copper, a metal is buried in a groove-shaped wiring pattern formed in an interlayer insulating film in advance, and a CMP (Chemica Mechanical) is used.
A wiring process called a damascene method, in which an excess metal film is removed by an IPolishing (chemical mechanical polishing) method to form a wiring, has become effective. This damascene method does not require wiring etching, and furthermore, the upper interlayer insulating film becomes naturally flat, so that the process can be simplified. Further, a dual damascene (Du) in which not only a wiring groove but also a contact hole is formed as a groove in the interlayer insulating film and the wiring groove and the contact hole are simultaneously filled with metal.
According to the adamascene method, it is possible to further reduce the number of wiring steps.

FIG. 2 shows a process of forming a copper wiring by a conventional dual damascene method. As shown in FIG. 2A, a low dielectric constant film (Low-k) 2 is formed on a semiconductor substrate 1 such as silicon oxide (SiO ₂ ), and an insulating film 3 made of silicon oxide is further formed thereon. Form. Then, a barrier metal 4 is formed in a contact hole 5 communicating with the surface of the insulating film 3 and the impurity diffusion region of the semiconductor substrate 1. As the barrier metal 4, Ta, Ti, Ta
A metal material such as N or TiN is formed by a known sputtering method. A copper wiring layer 6 is formed on the barrier metal 4 so as to fill a wiring groove (contact hole) 5.

Next, as shown in FIG. 2B, the copper wiring layer 6 on the barrier metal 4 is removed except for the portion inside the wiring groove 5. Next, as shown in FIG. 2C, the excess barrier metal 4 on the insulating film 3 is removed by a CMP method and flattened. Finally, as shown in FIG. 2D, a cap film 7 of silicon nitride (SiN) is formed on the insulating film 3.

In the conventional method of manufacturing a semiconductor device as described above, the low dielectric constant film 2 is used as the interlayer insulating film of the copper wiring layer 6, but the low dielectric constant film 2 has strength against CMP. Is small, so that the low dielectric constant film 2 may be scratched or peeled off, so that it cannot be used as a CMP surface. Therefore, conventionally, the insulating film 3 made of silicon oxide is further provided on the low dielectric constant film 2 to provide two insulating films, thereby ensuring the CMP resistance.

However, the low-dielectric-constant film 2 and the silicon oxide film 3 are liable to be peeled off by receiving a stress due to the heat treatment. In addition, the dielectric constant of the copper wiring layer 6 is increased by the thickness of the silicon oxide film 3, and the wiring resistance is increased. Furthermore, since the number of film layers in the whole semiconductor device is increased, the structure is complicated, and there is a problem that reliability is reduced.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. By using only one low-dielectric-constant insulating film, a highly reliable semiconductor device having a simple structure and a highly reliable semiconductor device are disclosed. It is intended to provide a manufacturing method.

[0009]

In order to achieve the above object, in a semiconductor device according to the present invention, a copper wiring layer is formed via a barrier metal in a contact hole formed in an insulating film on a semiconductor substrate. In a semiconductor device, the insulating film is formed of a single-layer low dielectric constant film.

[0010] A method of manufacturing a semiconductor device according to the present invention comprises:
Forming a low dielectric constant film on a semiconductor substrate, forming a wiring groove in the low dielectric constant film; forming a barrier metal on the surface of the low dielectric constant film and the wiring groove; Forming a copper wiring layer so as to fill the groove for wiring, removing the copper wiring layer on the barrier metal while leaving a portion in the wiring groove, and forming an extra barrier metal on the low dielectric constant film. And a step of removing

Further, the step of removing excess barrier metal on the low dielectric constant film can be performed by fluid polishing. Further, the step of removing the copper wiring layer on the barrier metal is performed by C
It can be done with either MP or fluid polishing.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the same members or those having the same functions as those in FIG. 2 are denoted by the same reference numerals. As shown in FIG. 1A, only a low dielectric constant film (Low-k) 2 is formed on a semiconductor substrate 1 such as silicon oxide (SiO ₂ ). As this low dielectric constant film, for example, SiF,
SiOCH, polyaryl ether, porous silica,
Examples include polyimide. Then, the barrier metal 4 is formed on the surface of the low dielectric constant film 2 and the inner wall of the wiring groove (contact hole) 5. As the barrier metal 4, Ta, T
A metal material such as i, TaN, or TiN is formed by a known sputtering method. On this barrier metal 4, a wiring groove 5 is formed.
Is formed to form a copper wiring layer 6.

Next, as shown in FIG. 1B, the copper wiring layer 6 on the barrier metal 4 is removed by polishing while leaving the portion in the wiring groove 5. Next, as shown in FIG. 1C, the excess barrier metal 4 on the low dielectric constant film 2 is removed by polishing. In this case, since the low dielectric constant film 2 is soft, CM
When the polishing is performed by the P method, when the barrier metal 4 is removed and the low dielectric constant film 2 is exposed, the low dielectric constant film 2 is easily scratched or peeled. Therefore, the removal step in FIG. 1C is performed by fluid polishing with a small pressure and a small impact.

Fluid polishing is a method in which a slurry in which fine abrasive grains are mixed is spouted from a fine hole of a polishing tool toward a surface to be polished to remove an extremely minute amount from the surface of the object to be polished. The slurry used for the fluid polishing is a liquid in which the low dielectric constant film 2 is not eroded, and the particle diameter of the fine abrasive grains is preferably 100 nm or less, and a neutral or alkaline pH of 7 to 14 is preferable. . By using such fluid polishing, scratching and peeling of the low dielectric constant film 2 can be prevented.

The removal of the copper wiring layer 6 shown in FIG.
Although the MP method may be used, fluid polishing can be used in this step if necessary. Finally, a cap film 7 of silicon nitride (SiN) is formed on the insulating film 3 as shown in FIG. In the case of a multilayer structure, a semiconductor device having the same structure is formed on the cap film 7.

[0016]

As described above in detail, according to the semiconductor device of the present invention, the insulating film is formed of a single low dielectric constant film, so that the conventional low dielectric constant film and silicon oxide film can be used. Of the copper wiring layer is in contact with the low dielectric constant film layer because there is no silicon oxide film, and therefore the dielectric constant of the copper wiring layer is low, and The resistance can be reduced, and
The structure is simple because the whole film layer of the semiconductor device is small,
There is an effect that reliability is improved. Further, according to the method of manufacturing a semiconductor device of the present invention, the insulating film is a low dielectric constant film.
Since only layers are required, the number of manufacturing processes is reduced, and there is an effect that manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a manufacturing process showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1 semiconductor substrate, 2 low dielectric constant film, 4 barrier metal, 5 wiring groove, 6 copper wiring layer

Claims (5)

[Claims] 1. A semiconductor device in which a copper wiring layer is formed via a barrier metal in a wiring groove formed in an insulating film on a semiconductor substrate, wherein the insulating film is formed of a single low dielectric constant film. A semiconductor device characterized by being performed. 2. A step of forming a low dielectric constant film on a semiconductor substrate; a step of forming a wiring groove in the low dielectric constant film; and forming a barrier metal on the surface of the low dielectric constant film and the wiring groove. Forming a copper wiring layer so as to fill the wiring groove; removing the copper wiring layer on the barrier metal while leaving a portion in the wiring groove; and forming the low dielectric constant film. Removing the excess barrier metal on the semiconductor device. 3. The method according to claim 2, wherein the step of removing excess barrier metal on the low dielectric constant film is performed by fluid polishing. 4. The method according to claim 2, wherein the step of removing the copper wiring layer on the barrier metal is performed by a CMP method. 5. The method for manufacturing a semiconductor device according to claim 2, wherein the step of removing the copper wiring layer on the barrier metal is performed by fluid polishing.