JP2007027254A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect an interconnection layer from impurities contained in an interlayer insulation film and impurities contained in a process atmosphere. <P>SOLUTION: After forming the interconnection layer 12 on an insulation layer 11, the surface of the interconnection layer 12 is thermally oxidized to form a protection film 13 for covering the exposed surface of the interconnection layer 12. On top of the interconnection layer 12 covered by the protection film 13, FSG film 14 and NSG film 15 are formed by high-density CVD or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device, and is particularly suitable for application to a method for protecting a wiring layer from external impurities.

As the density of semiconductor integrated circuits is increased, the wiring structure is miniaturized and the number of wiring layers is increasing. An interlayer insulating film is formed between the multilayered wiring layers in order to insulate these wiring layers.
Further, for example, in Patent Document 1, in order to improve device characteristics, yield, and reliability of a multilayer wiring structure, a predetermined amount is etched back after a through hole filling conductive material is grown on the entire surface, A method of patterning a metal wiring and etching the conductive material again using the metal wiring as a mask is disclosed.
Japanese Patent Laid-Open No. 5-129445

However, an interlayer insulating film is formed on the conventional wiring with the metal exposed. For this reason, there is a problem that impurities contained in the interlayer insulating film or impurities in the process atmosphere react with the metal of the wiring to increase the resistance of the wiring and cause the integrated circuit to malfunction.
SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device capable of protecting a wiring layer from external impurities, and a method for manufacturing the semiconductor device.

In order to solve the above-described problem, a semiconductor device according to one embodiment of the present invention has a wiring layer formed over an insulating layer and a barrier property against impurities, and covers an exposed surface of the wiring layer. A protective film and an interlayer insulating film formed on the wiring layer covered with the protective film are provided.
Thereby, it is possible to suppress the impurities contained in the interlayer insulating film and the impurities in the process atmosphere from entering the wiring layer. For this reason, impurities contained in the interlayer insulating film and impurities in the process atmosphere can react with the metal of the wiring to increase the resistance of the wiring, and malfunction of the integrated circuit can be reduced.

In the semiconductor device according to one embodiment of the present invention, the protective film is a thermal oxide film formed by thermally oxidizing the surface of the wiring layer.
As a result, the entire surface of the wiring layer can be covered with a protective film by thermally oxidizing the surface of the wiring layer, and wiring can be protected from the intrusion of impurities contained in the interlayer insulating film and impurities in the process atmosphere. The layer can be protected.

  According to the semiconductor device of one embodiment of the present invention, the wiring layer includes a TiN / Al—Cu / Ti / TiN structure, a TiN / Al / Ti / TiN structure, a TiN / Al—Cu / TiN structure, a TiN. / Ti / Al-Cu / Ti / TiN structure, TiN / Ti / Al / Ti / TiN structure, Ti / TiN / Al-Cu / Ti / TiN structure, Ti / TiN / Al / Ti / TiN structure, Ti / TiN It is a / Ti / Al-Cu / Ti / TiN structure or a Ti / TiN / Ti / Al / Ti / TiN structure.

As a result, it is possible to provide the wiring layer with a function as a barrier metal for silicon, and it is possible to reduce the reflectance of the wiring layer and to miniaturize the wiring layer while suppressing the generation of Al whiskers. Can do.
In addition, according to the method for manufacturing a semiconductor device of one embodiment of the present invention, the exposed surface of the wiring layer is formed by performing a step of forming a wiring layer on the insulating layer and thermally oxidizing the surface of the wiring layer. The method includes a step of forming a protective film to be covered, and a step of forming an interlayer insulating film on the wiring layer covered with the protective film.

As a result, the entire surface of the wiring layer can be covered with a protective film by thermally oxidizing the surface of the wiring layer, and wiring can be protected from the intrusion of impurities contained in the interlayer insulating film and impurities in the process atmosphere. The layer can be protected.
According to the method for manufacturing a semiconductor device of one embodiment of the present invention, the temperature during thermal oxidation of the surface of the wiring layer is 450 ° C. or lower.

Thereby, it can suppress that a pinhole is formed at the time of thermal oxidation of a wiring layer, and can protect a wiring layer stably.
Further, according to the method for manufacturing a semiconductor device according to one aspect of the present invention, a step of forming a wiring layer on the insulating layer, a step of forming a protective film covering the exposed surface of the wiring layer by CVD, Forming an interlayer insulating film on the wiring layer covered with the protective film.

  This makes it possible to cover the exposed surface of the wiring layer with a protective film while appropriately selecting the type of protective film, and to prevent the wiring layer from being intruded by impurities contained in the interlayer insulating film or impurities in the process atmosphere. Can be protected.

Hereinafter, a semiconductor device and a manufacturing method thereof according to embodiments of the present invention will be described with reference to the drawings.
1 and 2 are cross-sectional views illustrating a method of manufacturing a semiconductor device according to an embodiment of the present invention.
In FIG. 1A, for example, TiN / Al—Cu / Ti / TiN is sequentially sputtered on the insulating layer 11 and is formed of TiN / Al—Cu / Ti / TiN using a photolithography technique and an etching technique. By patterning the film, the wiring layer 12 including the TiN film 12a, the Al—Cu film 12b, the Ti film 12c, and the TiN film 12d is formed on the insulating layer 11.

  Next, as shown in FIG. 1B, the surface of the wiring layer 12 is thermally oxidized to form a protective film 13 that covers the exposed surface of the wiring layer 12. In addition, it is preferable to set the film thickness of the protective film 13 in the range of 50-100cm. As a result, it is possible to ensure barrier properties against impurities while suppressing the erosion of the wiring layer 12 due to thermal oxidation. The temperature of the thermal oxidation of the surface of the wiring layer 12 is preferably set to 400 to 450 ° C. Thereby, it can suppress that a pinhole is formed at the time of the thermal oxidation of the wiring layer 12, and can protect the wiring layer 12 stably.

Next, as shown in FIG. 1C, an FSG (fluorinated silicate glass) film 14 is formed on the wiring layer 12 covered with the protective film 13 by a method such as high-density CVD.
Next, as shown in FIG. 1D, for example, NSG (non-doped silicate glass) film 15 is formed on FSG film 14 by performing CVD using TEOS (tetraethoxysilane) gas.

Next, as shown in FIG. 2A, the surface of the NSG film 15 is planarized by polishing the surface of the NSG film 15 using, for example, CMP (chemical mechanical polishing).
Next, as shown in FIG. 2B, the FSG film 14 and the NSG film 15 are patterned by using a photolithography technique and an etching technique to form an opening that exposes the surface of the wiring layer 12. Then, a barrier metal film 16 is formed on the NSG film 15 so as to cover the surface in the opening by a method such as sputtering. As the barrier metal film 16, for example, a Ti / TiN structure can be used. Then, for example, a tungsten film is formed on the barrier metal film 16 so as to fill the opening by performing CVD using a WF ₆ / H ₂ -based gas. Then, by thinning the barrier metal film 16 and the tungsten film, the tungsten plug 17 is formed in the opening, and the surface of the NSG film 15 is exposed.

  Here, by covering the exposed surface of the wiring layer 12 with the protective film 13 and forming the FSG film 14 on the wiring layer 12, impurities such as fluorine contained in the FSG film 14 or in the process atmosphere Impurities can be prevented from entering the wiring layer 12. For this reason, it is possible to prevent impurities contained in the FSG film 14 or impurities in the process atmosphere from reacting with the metal of the wiring layer 12 to increase the resistance of the wiring layer 12, thereby reducing malfunction of the integrated circuit. Can do.

In the above-described embodiment, the method of configuring the protective film 13 covering the exposed surface of the wiring layer 12 with an oxide film formed by thermal oxidation of the wiring layer 12 has been described. You may make it form the protective film 13 which coat | covers a surface by CVD method.
In the above-described embodiment, the method using the TiN / Ti / Al-Cu / Ti / TiN structure as the wiring layer 12 has been described. However, as the wiring layer 12, a TiN / Al / Ti / TiN structure, TiN / Al-Cu / TiN structure, TiN / Al-Cu / Ti / TiN structure, TiN / Ti / Al / Ti / TiN structure, Ti / TiN / Al-Cu / Ti / TiN structure, Ti / TiN / Al / Ti / A TiN structure, a Ti / TiN / Ti / Al-Cu / Ti / TiN structure, a Ti / TiN / Ti / Al / Ti / TiN structure, or the like may be used.

  In the above-described embodiment, the method for forming the wiring layer in the semiconductor device has been described as an example. However, the wiring forming method according to the present invention is not limited to the semiconductor device, and other than the semiconductor device, for example, a liquid crystal You may make it apply to a display apparatus, an organic EL element, a buildup multilayer wiring board, etc.

Sectional drawing which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention. Sectional drawing which shows the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention.

Explanation of symbols

  11 insulating layer, 12 wiring layer, 12a, 12d TiN film, 12c Ti film, 12b Al-Cu film, 13 protective film, 14 FSG film, 15 NSG film, 16 barrier metal film, 17 tungsten plug

Claims (6)

A wiring layer formed on the insulating layer;
A protective film having a barrier property against impurities and covering the exposed surface of the wiring layer;
A semiconductor device comprising: an interlayer insulating film formed on the wiring layer covered with the protective film.   2. The semiconductor device according to claim 1, wherein the protective film is a thermal oxide film formed by thermally oxidizing the surface of the wiring layer. The wiring layer has a TiN / Al-Cu / Ti / TiN structure, a TiN / Al / Ti / TiN structure, a TiN / Al-Cu / TiN structure, a TiN / Ti / Al-Cu / Ti / TiN structure, a TiN / Ti structure. / Al / Ti / TiN structure, Ti / TiN / Al-Cu / Ti / TiN structure, Ti / TiN / Al / Ti / TiN structure, Ti / TiN / Ti / Al-Cu / Ti / TiN structure or Ti / TiN 3. The semiconductor device according to claim 1, wherein the semiconductor device has a / Ti / Al / Ti / TiN structure. Forming a wiring layer on the insulating layer;
Forming a protective film covering the exposed surface of the wiring layer by thermally oxidizing the surface of the wiring layer;
And a step of forming an interlayer insulating film on the wiring layer covered with the protective film.   The method for manufacturing a semiconductor device according to claim 4, wherein the temperature during thermal oxidation of the surface of the wiring layer is 450 ° C. or less. Forming a wiring layer on the insulating layer;
Forming a protective film covering the exposed surface of the wiring layer by CVD;
And a step of forming an interlayer insulating film on the wiring layer covered with the protective film.

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