JP2000058642A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent decomposition of an organic SOG film part comprising a methyl group as an interlayer insulating film in a connection hole when peeling a resist mask in an oxygen atmosphere. SOLUTION: The surface of an organic SOG(spin on glass) 14 comprising a methyl group on a semiconductor substrate 11, which comprises a conductive layer 13 such as a diffused layer, wiring layer, etc., is oxidized to form a reform layer 15. After the reform layer 15 and the interlayer insulating film 14 are etched with a resist mask as a mask for forming a connection hole 17 reaching the conductive layer 13, a filling material 18 of a material which is different from the interlayer insulating film 14 for etching selection-ratio is embedded in the connection hole 17, and then the surface of the filling material 18 is oxidiezed to form a reform layer 19. After a resist mask 16 is peeled off in an oxygen atmosphere, the filled material 18 is selectively removed to form a metal wiring layer 20 in the connection hole 17. Since the sidewall of the interlayer insulating film 14 in the connection hole 17 is covered with the filled material 18 when peeling the resist mask, the interlayer insulating film is prevented from decomposing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming an electrode wiring using an organic SOG containing a methyl group as an interlayer insulating film.

[0002]

2. Description of the Related Art As the density of integrated circuits has increased and the speed of the integrated circuits has increased, it has recently become a major issue to suppress the wiring capacitance in the integrated circuits. For this reason, an organic SOG film containing a methyl group having a dielectric constant of about 2.8 lower than a silicon oxide film (SiO ₂ ) having a dielectric constant of about 4.0 to 4.5 is used as an interlayer insulating film between the wirings. It has become. Next, a conventional method for forming an electrode wiring will be described with reference to FIG. FIG. 2 is a schematic process cross-sectional view showing a process of forming an electrode wiring.

First, as shown in FIG. 2A, a semiconductor substrate 21 having a conductive layer 22 such as a diffusion layer or an electrode metal is placed on a semiconductor substrate 21.
An organic SOG film (interlayer insulating film) 23 containing a methyl group is formed. Next, as shown in FIG. 2B, when the resist mask is stripped using a plasma containing an oxygen gas, which will be described later, reactive ions using oxygen as a reactive gas are used in order to prevent deterioration of the interlayer insulating film. By etching, methyl groups are removed from the surface of the interlayer insulating film 23 to form a modified layer 24 made of an oxide layer.

[0004] Next, as shown in FIG. 2 (c), a resist film is applied on the modified layer 24, and a resist pattern is exposed and developed by electron beam exposure.
A resist mask 25 having an opening at a position corresponding to is formed.

Next, as shown in FIG. 2D, using the resist mask 25 as a mask, octafluorocyclobutane (C ₄ F ₈ ), carbon monoxide (CO), and argon (A) are used.
The modified layer 24 and the interlayer insulating film 23 are etched by reactive ion etching using a mixed gas of r) and oxygen (O ₂ ) as a reaction gas, and a connection hole 26 reaching the conductive layer 22 is formed. Thereafter, as shown in FIG. 2E, the resist mask 25 is peeled off using a plasma containing oxygen.

After that, as shown in FIG. 2F, a metal film 27 of Al or the like is buried in the connection hole 26. Thereafter, a metal wiring as an upper layer wiring is formed as necessary.

However, in the conventional method for forming an electrode wiring, in the step of stripping the resist mask, the interlayer insulating film in the connection hole is exposed to an oxygen atmosphere, so that methyl groups contained in the interlayer insulating film are oxidized. And is transformed into a hygroscopic film. Due to the change of the interlayer insulating film into a hygroscopic film,
The metal wiring corrodes and lowers the reliability of the wiring. In addition, the oxidation of the methyl group contained in the interlayer insulating film increases the dielectric constant, which causes a problem such as an increase in wiring capacitance. In order to prevent the deterioration of the interlayer insulating film, a method of forming a modified layer composed of an oxide film by performing a reforming process using oxygen plasma on a side wall in the connection hole is disclosed in, for example, T.I. Furusa
wa and Y. Homma: Extended A
bracts of 1mt. Conf. on S
olid State Devices and Ma
tertals, pp. 145 (1996).

However, in this method, it is possible to modify the side wall in the connection hole up to an aspect ratio of the connection hole of about 2, but when the aspect ratio exceeds 2, the modification treatment by the plasma treatment is performed. Therefore, there is a problem that the interlayer insulating film is deteriorated.

[0009]

As described above, in any of the conventional methods for forming an electrode wiring, the side wall inside the connection hole of the interlayer insulating film is exposed to an oxygen atmosphere in the step of removing the resist mask. Since the methyl group in the film is oxidized, the dielectric constant of the interlayer insulating film increases and the wiring capacity increases, and the interlayer insulating film changes to a hygroscopic film, thereby lowering the reliability of the metal wiring. There is a problem.
The present invention has been made in view of the above problems, and provides a method for manufacturing a semiconductor device capable of preventing deterioration of an interlayer insulating film in a step of removing a resist mask in an oxygen atmosphere.

[0010]

In order to achieve the above object, in a method of manufacturing a semiconductor device according to the present invention, a step of forming an interlayer insulating film made of organic SOG containing a methyl group on a semiconductor substrate having a conductive layer is provided. Modifying the surface of the interlayer insulating film to form a modified layer; forming a resist mask on the modified layer; and forming the modified layer and the interlayer using the resist mask as a mask. Etching an insulating film to form a connection hole reaching the conductive layer; filling the connection hole with a filling material made of a material having a different etching selectivity from the interlayer insulating film; Forming a modified layer by modifying the surface, removing the resist mask using oxygen plasma, and removing the filler from the connection hole;
Filling the connection hole with a conductive material. Further, the filling material is made of one selected from hydrogensilsquioxane, polysilane, and silicon oxide film.

Further, the filling material may be a spin coating method,
Alternatively, it is characterized by being buried in the connection hole by a CVD method. Further, it is characterized in that the filling material is removed by using a liquid or gas containing HF or an alkaline solution. Further, the modified layer on the surface of the filling material is formed by plasma containing oxygen.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a schematic process sectional view showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.

First, as shown in FIG. 1A, a lower metal wiring layer (conductive layer) 13 made of, for example, Al is buried in an insulating film (SiO ₂ ) 12 on a silicon substrate 11, and the lower metal layer is formed. On the insulating film 12 including the wiring layer 13, an organic SOG film 14 (interlayer insulating film) containing a methyl group having a dielectric constant of about 2.8, such as polymethylsiloxane, having a thickness of 9 is formed.
000 na. This organic SOG film 14 is made of organic S
OG is applied by a spin coating method, and further formed by baking at 150 ° C. for 30 seconds, 200 ° C. for 30 seconds, and 450 ° C. for 30 minutes.

Next, as shown in FIG. 1B, the surface of the organic SOG film 14 is oxidized by about 10 nm to form a modified layer 15 made of an oxide film. This modified layer 15 is to prevent the organic SOG film 14 from being deteriorated by oxygen in a step of peeling the resist pattern film using plasma containing oxygen, which will be described later.

The modified film 14 is formed by a magnetron reactive ion etching (RIE) apparatus using a plasma generated under the conditions of an oxygen (O ₂ ) gas flow rate of 100 sccm, RF power of 200 W and a reaction pressure of 100 mTorr for 60 seconds. Formed by exposure.

Thereafter, as shown in FIG. 1C, a resist film having a thickness of 4500 nm is formed on the modified film 15.
Next, for example, a predetermined pattern is exposed and developed by electron beam exposure to form a resist pattern film 16 having an opening at a position corresponding to the lower metal wiring layer 13.

Next, as shown in FIG. 1D, octaflucyclooctane (C
₄ F ₈ ) / carbon monoxide (CO) / argon (Ar) / oxygen (O ₂ ) = 10/50/200/10 sccm, RF power is 1700 W, reaction pressure is 40 mTorr, and plasma is generated for 180 seconds. By exposing and etching the modified layer exposed from the resist pattern film 16 and the organic SOG film 14 thereunder, a connection hole 17 reaching the lower metal wiring layer 13 is formed. After that, as shown in FIG.
A filling material 18 made of a material having a different etching selectivity from the G film, for example, hydrogen silsesquioxin (HSQ) is filled. The filling material 18 is applied to at least the organic SOG film 14 and the modified film 1 by spin coating so that the organic SOG film 14 is not exposed on the side surface inside the connection hole 17.
5 and preferably up to the height of the upper surface of the modified film 15.

However, the filling material 18 may be filled up to the height of the upper surface of the resist pattern film 16. Next, as shown in FIG. 1F, in the step of removing the resist pattern film, in order to prevent the alteration of the filling material, the filling material 18 is formed under the same conditions as those for modifying the surface of the organic SOG film. The surface is oxidized to form a modified layer 19 made of an oxide film.

Next, as shown in FIG. 1 (g), the resist pattern film 16 is made to have a microwave power of 2.45 GHz.
Z, RF power 1500 W, reaction pressure 0.45 Torr
The resist pattern film 16 is peeled off by exposing it to an oxygen plasma atmosphere generated at a flow rate of 1000 sccm for r and O ₂ for 60 seconds.

Thereafter, as shown in FIG. 1 (h), the filling material 18 is etched with a 1.0% aqueous solution of hydrofluoric acid (HF) for 30 seconds to remove the filling material 18. At this time, the modified layer 19 on the surface of the filling material 18 is also removed.

Next, as shown in FIG. 1 (i), a metal wiring layer 18 of Al or the like is filled in the connection hole 17 after removing the filling material 18, and if necessary, the metal wiring layer 18 is formed. 2
An upper metal wiring layer is formed on the first metal layer.

According to the method of manufacturing a semiconductor device of the above embodiment, the filling is buried in the connection to cover the side wall of the interlayer insulating film in the connection hole, and then the resist is stripped by oxygen plasma.

Therefore, the interlayer insulating film in the connection hole is not exposed to oxygen plasma, maintains its original dielectric constant, does not change into a hygroscopic film, suppresses the capacitance between wirings, and has high reliability. Is obtained.

In the above embodiment, methylsiloxane is used as the organic SOG film (interlayer insulating film) containing a methyl group, but ethylsiloxane may be used. As the filling material, inorganic SOG hydrogen silsesquioxane was used. However, a polymer having an organic substance (carbon) in a polymer having a silicon-silicon bond in the main chain is referred to as polysilane, for example, polydiphenylsilane, polyphenyl. Methylsilane or a silicon oxide film may be used.

[0025]

According to the method of manufacturing a semiconductor device of the present invention, the filling is buried in the connection hole to cover the side wall of the interlayer insulating film in the connection hole, and then the resist is stripped by oxygen plasma.

Therefore, the interlayer insulating film in the connection hole is not exposed to oxygen plasma, retains the original dielectric constant, does not change into a hygroscopic film, suppresses the wiring capacitance and achieves high reliability. A metal wiring is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a method for manufacturing a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic process sectional view showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

 11, 21 ... silicon substrate (semiconductor substrate) 12 ... insulating film 13, 22 ... lower metal wiring layer (conductive layer) 14, 23 ... interlayer insulating film 15, 19, 24 ... Material layer 16, 25 Resist mask 17, 26 Connection hole 18 Filling material 20, 27 Metal wiring film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M104 AA01 BB02 CC01 DD08 DD09 DD20 EE18 5F033 AA12 AA15 AA29 AA64 DA04 DA13 DA34 EA02 EA06 EA11 EA29 FA03

Claims (5)

[Claims] A step of forming an interlayer insulating film made of organic SOG containing a methyl group on a semiconductor substrate having a conductive layer;
Forming a modified layer by modifying the surface of the interlayer insulating film;
Forming a resist mask on the modified layer; etching the modified layer and the interlayer insulating film using the resist mask as a mask to form a connection hole reaching the conductive layer; A step of burying a filling material made of a material having a different etching selectivity from the interlayer insulating film, a step of modifying the surface of the filling material to form a modified layer, and using the resist mask with oxygen plasma. And removing the filler material from the connection hole, and filling the connection hole with a conductive material. 2. The method according to claim 1, wherein the filling material comprises one selected from hydrogen silsquioxane, polysilane, and a silicon oxide film. 3. The method according to claim 1, wherein the filling material is buried in the connection holes by a spin coating method or a CVD method. 4. The method according to claim 1, wherein the removing of the filling material is performed by using a solution or gas containing HF or an alkaline solution. 5. The method according to claim 1, wherein the formation of the modified layer on the surface of the filling material is performed by plasma containing oxygen gas.