JP3421890B2 - Polishing slurry and method for manufacturing semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of flattening an interlayer insulating film in a semiconductor device, and more specifically, a polishing slurry used for polishing an interlayer insulating film made of an organic resin, and a polishing slurry using the same. The present invention relates to a method for manufacturing a semiconductor device capable of satisfactorily flattening an interlayer insulating film.

[0002]

2. Description of the Related Art In the wiring technology for semiconductor devices, miniaturization and multi-layering are progressing toward higher density devices. However, high integration may be a factor that reduces the reliability of wiring. That is, the step size of the interlayer insulating film becomes large and steep due to the miniaturization of wiring and the progress of multi-layering, and the processing accuracy and reliability of the wiring formed thereon deteriorates. Due to the fear of such a decrease in reliability, the step coverage of Al wiring cannot be greatly improved in the related art, and therefore there has been a demand for a technique for improving the flatness of the interlayer insulating film.

From such a background, various insulating film forming techniques and flattening techniques have been conventionally developed.
However, in such conventional technology,
When applied to a multi-layered wiring layer, its flatness is insufficient when the wiring spacing is wide, and it does not work on the interlayer insulation film between wirings.
The occurrence of such a problem causes a new problem such as a connection failure between the wirings. In addition to such an insulating film forming technique and its planarization technique, in recent years, as a planarization technique, a mechanochemical polishing technique for polishing fine particles of silicon oxide in a basic solution has been provided. Has been implemented in the department.

[0004]

By the way, in recent years, as the device rules have been miniaturized, the problem of interlayer capacitance delay due to the interlayer insulating film has been pointed out, and it is necessary to reduce the dielectric constant of the interlayer insulating film. Is increasing. The low dielectric constant film is roughly classified into an inorganic oxide and an organic resin. Regarding the inorganic oxide, for example, “25th SSDM′93
P161 ”,“ Procedures 1a-ZV-9 of the 40th Joint Lecture of the Applied Physics Society of Japan ”, as described in TEO.
Add C ₂ F ₆ or NF ₃ as a fluorine source to S, and add S
A method of forming an iOF film has been proposed.

However, it is known that in these methods, the film quality deteriorates with an increase in the fluorine content to be introduced, and the film exhibits remarkable hygroscopicity. In contrast,
For example, “Proceedings 3 of the 40th Joint Lecture of the Japan Society of Applied Physics”
1p-ZV-1 ", Si containing fluorine in the source gas structure for the purpose of stabilizing the film quality.
Investigations have been made to form a SiOF film using an F ₄ / O ₂ system gas. And according to such examination, Si
It is said that a low dielectric constant interlayer insulating film having a relative dielectric constant of about 3.0 can be formed by stabilizing the film quality using an F ₄ / O ₂ based gas.

However, in order to obtain an interlayer insulating film having a relative dielectric constant of less than this, it is necessary to use an organic resin because the inorganic oxide has a limit. Examples of the organic resin include, for example, “Proceedings of the 54th Annual Meeting of the Applied Physics Society of Japan,
28p-X-16 ", a polyimide-based compound, polytetrafluroethylene (trade name: Teflon), a polycarbonate-based compound, a polysiloxane-based compound, and a parylene-based compound.

However, although the organic resin has a lower dielectric constant than the inorganic oxide, when the above-mentioned mechanochemical polishing technique is applied to the flattening of the interlayer insulating film made of the organic resin, the organic resin has a low dielectric constant. Since the hardness of the polishing layer is low, new problems occur such as occurrence of polishing scratches due to silicon oxide fine particles and the fine particles being embedded in the interlayer insulating film. Therefore, an abrasive that can be applied to polishing an interlayer insulating film made of an organic resin, that is, that uses soft abrasive particles and that can be easily removed after polishing, and a polishing technique using the same have been earnestly desired. The present invention has been made in view of the above circumstances, and an object thereof is to provide a polishing slurry suitable for planarizing an interlayer insulating film with an organic resin, and a method for manufacturing a semiconductor device using the same. To do.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found a polishing slurry capable of stably polishing an interlayer insulating film made of an organic resin, Completed the invention. That is, the polishing slurry of the present invention comprises water-soluble inorganic compound fine particles dispersed in a non-aqueous dispersion medium. Examples of the water-soluble inorganic compound fine particles, carbonate of metal ions, sulfates, nitrates, ammonium salts, halides, perchlorates, Ho
C, phosphate, Ahi salts and the like, or these one or two is used. Further, as the non-aqueous dispersion medium, methyl alcohol, ethyl alcohol, isopropyl alcohol, etc. are used. Although the amount of the water-soluble inorganic compound fine particles dispersed in the non-aqueous dispersion medium varies depending on the type of the fine particles used and the type of the dispersion medium, the important ratio is about 2% to 20% of the whole, It is preferable because the fluidity of the slurry can be secured and the polishing can be effectively performed. The particle size of the fine particles is about 10 to 100 nm as the primary particle size and 20 as the secondary particle size.
The thing of about 0-1000 nm is used.

According to the method of manufacturing a semiconductor device of the present invention, an organic insulating resin is used to cover the stepped portion on a substrate having a stepped portion formed on the surface, and an interlayer insulating film is formed on the substrate, This is a method of flattening the interlayer insulating film by polishing with a polishing slurry, and as the organic resin, polyimide, polytetrafluoroethylene, polysiloxane, fluorinated silicate, fluorinated polyimide, and pores are used. A polymer, a polycarbonate-based polysiloxane, or one or more of a parylene-based compound is used, and as the polishing slurry, a slurry in which water-soluble inorganic compound fine particles are dispersed in a non-aqueous dispersion medium is used. I am trying.

[0010]

According to the polishing slurry of the present invention, since the water-soluble inorganic compound fine particles are dispersed in the non-aqueous dispersion medium, for example, when calcium carbonate is used as the water-soluble inorganic compound fine particles, it is It has a hardness lower than that of inorganic oxides, and therefore it is not preferable to use it for polishing an interlayer insulating film made of the inorganic oxides, but it is more satisfactory than organic resins such as polyimide. Since it has a very high hardness, it can be sufficiently used for polishing the interlayer insulating film made of the polyimide. Since the water-soluble inorganic compound fine particles have a lower hardness than the inorganic oxide as described above, it is possible to prevent inconveniences such as scratches or the like being generated in the interlayer insulating film during polishing and fine particles being embedded. Further, since the fine particles are dispersed in the non-aqueous dispersion medium, the fine particles do not dissolve in the dispersion medium during polishing, which enables stable polishing. Further, if the particles are washed with water after polishing, the fine particles are dissolved in water, so that the generation of particles on the interlayer insulating film or the like due to the fine particles is prevented.

According to the method of manufacturing a semiconductor device of the present invention,
Since the interlayer insulating film made of an organic resin is polished using the polishing slurry, it is possible to prevent the inconveniences such as scratches and the like from being embedded in the interlayer insulating film and the fine particles embedded in the interlayer insulating film, as described above, and stable. Polishing becomes possible, and generation of particles due to polishing fine particles is prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on a method of manufacturing a semiconductor device. The present manufacturing method includes a step of forming an interlayer insulating film on the base by covering the step with an organic resin on a base having a step formed on the surface, and polishing the interlayer insulating film. And a step of flattening by polishing with a slurry. Examples of the organic resin include one or more of polyimide, polytetrafluoroethylene, polysiloxane, fluorinated silicate, fluorinated polyimide, polymer having pores, polycarbonate polysiloxane, and parylene compound. Used. Further, as the polishing slurry,
The above-mentioned slurry, that is, the one obtained by dispersing the water-soluble inorganic compound fine particles in the non-aqueous dispersion medium is used.

First, before explaining the manufacturing method of the present invention, an example of the polishing apparatus used in the present invention will be described with reference to FIG. Although a single-wafer polishing apparatus will be described here, it is needless to say that the arrangement of the wafer mounting device and the method of use are not particularly limited. In FIG. 3, reference numeral 1 is a polishing device, 2
Is a wafer which is a substrate of the present invention. The polishing apparatus 1 includes a polishing plate 3 for performing a polishing process, and a sample holder 4 that holds a wafer 2 to be polished. A pad 5 is fixed to the upper surface of the polishing plate 3, and the polishing slurry 7 supplied from the slurry supply pipe 6 stays and flows on the pad 5. Further, on the bottom surface of the polishing plate 3, the polishing plate 3
A rotary shaft 8 for rotating the motor is provided, and a drive source (not shown) such as a motor is connected to the rotary shaft 8.

The sample holder 4 is of a vacuum chuck type, and holds and fixes the wafer 2 on its lower surface side.
The sample holder 4 is also provided with a rotary shaft 9 on its upper surface for rotating the sample holder 4.
A drive source (not shown) such as a motor is connected to the. The polishing plate 3 is formed to be sufficiently larger than the sample holder 4, and the sample holder 4 is arranged above one side of the polishing plate 3, and the lower surface thereof is on the upper surface of the pad 5 of the polishing plate 3. They are arranged in parallel. The sample holder 4 is connected to an elevating device (not shown) so that the wafer 2 fixed to the lower surface of the sample holder 4 is pressed against the upper surface of the pad with a predetermined pressure.

The polishing apparatus 1 having such a structure
After fixing the wafer 2 to the sample holder 4, the polishing plate 3 and the sample holder 4 are rotated while supplying the polishing slurry 7 from the slurry supply pipe 6 onto the pad 5, and the sample is held in that state. The wafer 4 is lowered by lowering the table 4.
By pressing the pad 2 against the surface of the pad 5, the wafer 2 can be uniformly polished to a predetermined thickness.

(First Embodiment) Next, a first embodiment using the polishing apparatus 1 shown in FIG. 3 will be described. In the first embodiment, first, as shown in FIG.
0, a silicon oxide film 11 is formed, and A is further formed on it.
A wafer on which the 1 wiring 12 was formed, that is, a substrate 13 having a step formed on the surface was prepared. Next, the surface of the base body 13 is covered with the Al wiring 12 and
An organic resin was applied by a spin coating method so as to fill the step formed by, and an interlayer insulating film 14 made of the resin was formed at room temperature as shown in FIG. 1 (b). Here, in this embodiment, polyimide is used as the resin for forming the interlayer insulating film 14.

Next, the substrate 13 having the interlayer insulating film 14 formed thereon is fixed to the sample holder 4 of the polishing apparatus 1 shown in FIG. 3, and the interlayer insulating film 14 is polished and flattened under the following conditions. As shown in (c), the planarized interlayer insulating film 14a was formed. Polishing conditions Rotational speed of polishing plate 13; 17 [rpm] Rotational speed of wafer holder; 17 [rpm] Polishing pressure; 5.5 × 10 ³ [Pa] Slurry flow rate; 225 [ml / min] Here, for polishing As the slurry 7, calcium carbonate [CaCO ₃ ] fine particles having a primary particle diameter of 50 nm and a secondary particle diameter of 200 nm were used as fine particles for polishing, and methyl alcohol was used as a dispersion medium.
The dispersion concentration of calcium carbonate in methyl alcohol was 5% by weight. After polishing in this manner, the substrate 13 was washed with water to wash away the slurry, and the polishing fine particles (CaCO ₃ ) were dissolved in water and removed from the substrate 13.

When the surface of the interlayer insulating film 14a thus polished and flattened is observed with an optical microscope, scratches and embedding of fine particles into the interlayer insulating film 14a are not observed, and the interlayer insulating film 14a is not observed. It was confirmed that 14a had good flatness. Separately, for comparison, the interlayer insulating film 14a was polished using silicon oxide fine particles, and the surface was observed in the same manner. As a result, scratches and fine particles were embedded in the surface of the interlayer insulating film 14a made of polyimide resin. Was observed.

(Second Embodiment) In the second embodiment, first, as shown in FIG. 2A, a silicon oxide film 21 is formed on a semiconductor substrate 20, and an Al wiring 22 is further formed thereon. A wafer, that is, a substrate 23 having a step formed on its surface was prepared. Next, on the surface of the base body 23, as shown in FIG.
As shown in (b), the plasma CV covers the Al wiring 22.
The silicon oxide film 24 is formed by the D method, and further, the organic resin is applied by the spin coating method so as to cover the silicon oxide film 24 and fill the step formed by the Al wiring 22. An interlayer insulating film 25 made of the resin was formed. Here, in the present embodiment, the interlayer insulating film 25
Polytetrafluroethylene (trade name: Teflon) was used as a resin for forming the resin, and this was formed by a plasma polymerization method. The silicon oxide film 24 formed on the Al wiring 22 is used as a polishing stopper layer and is for stabilizing the polishing / planarizing process described later.

Then, as in the case of the first embodiment, the layer
The substrate 23 having the inter-layer insulation film 25 formed thereon is polished by the polishing apparatus shown in FIG.
It is fixed to the sample holder 4 of the table 1 and the silicon 24 is polished.
The interlayer insulating film 25 as a top layer is polished and flattened under the following conditions.
Insulation, which is flattened as shown in Fig. 2 (c)
The film 25a was formed.     Polishing condition         Number of rotations of the polishing plate 13; 17 [rpm]         Number of rotations of wafer holder: 17 [rpm]         Polishing pressure: 5.5 × 10³  [Pa]         Slurry flow rate: 200 [ml / min] Here, the polishing slurry 7 includes fine particles for polishing.
And its particle size is 30 nm as the primary particle size, and the secondary particle
Aluminum sulfate with a diameter of 300 nm [Al ₂(SO
_Four)₃] Using fine particles and isopropyl alcohol as a dispersion medium
Call was used. Also, aluminum sulfate
Dispersion concentration in pill alcohol is 5% by weight
And

After polishing in this manner, the substrate 23 is washed with water to wash away the slurry, and the polishing fine particles [Al ₂ (SO ₄ ) ₃ ] are dissolved in water to obtain the substrate 2.
3 removed from above. When the surface of the interlayer insulating film 25a thus polished and flattened is observed with an optical microscope, scratches and embedding of fine particles into the interlayer insulating film 25a are not observed, and the interlayer insulating film 25a is excellent. It was confirmed that the film had excellent flatness.

[0022]

As described above, the polishing slurry of the present invention has the following excellent effects because it is a dispersion of water-soluble inorganic compound fine particles in a non-aqueous dispersion medium. Since the water-soluble inorganic compound fine particles have a hardness sufficiently higher than that of the organic resin, it can be sufficiently used for polishing the interlayer insulating film made of the organic resin. Since the water-soluble inorganic compound fine particles have a hardness lower than that of the inorganic oxide, it is possible to prevent the inconvenience that scratches or the like are generated in the interlayer insulating film during polishing and the fine particles are embedded. Further, since the fine particles are dispersed in the non-aqueous dispersion medium, the fine particles do not dissolve in the dispersion medium during polishing, and thus stable polishing can be performed. Further, washing with water after polishing dissolves the fine particles in water, so that it is possible to prevent generation of particles on the interlayer insulating film or the like due to the fine particles.

According to the method of manufacturing a semiconductor device of the present invention,
Since the interlayer insulating film made of an organic resin is polished using the polishing slurry, it is possible to prevent the inconveniences such as scratches and the like from being embedded in the interlayer insulating film and the fine particles embedded in the interlayer insulating film, as described above, and stable. Polishing can be performed, and generation of particles due to polishing fine particles can be prevented.

[Brief description of drawings]

1A to 1C are side cross-sectional views of a main part for explaining a first embodiment of a manufacturing method of the present invention in the order of steps.

2 (a) to 2 (c) are cross-sectional views of the essential part for explaining the second embodiment of the manufacturing method of the present invention in the order of steps.

FIG. 3 is a schematic configuration diagram of an example of a polishing apparatus used in the manufacturing method of the present invention.

[Explanation of symbols]

1 Polishing device 2 wafers 7 Polishing slurry 10, 20 Semiconductor substrate 12, 22 Al wiring 13, 23 Base 14, 25 Interlayer insulation film 14b, 25b Interlayer insulating film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C09K 3/14 550 C09K 3/14 550C (56) References JP-A-49-76470 (JP, A) JP-A-7-288253 (JP, A) JP 2-1588684 (JP, A) JP 7-86216 (JP, A) JP 50-99467 (JP, A) JP 8-153696 (JP, A) Kaihei 8-295875 (JP, A) JP-A 1-135026 (JP, A) JP-A 8-22970 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21 / 304 B24B 37/00 C09K 3/14

Claims (3)

(57) [Claims] 1. An interlayer insulating film of a semiconductor device is flattened by polishing.
It is a polishing slurry that is used when supporting, and in which water-soluble inorganic compound fine particles are dispersed in a non-aqueous dispersion medium.
The water-soluble inorganic compound fine particles are metal ion carbonates,
A polishing slurry comprising one or more of sulfates, nitrates, ammonium salts, halogen compounds, perchlorates, borates , phosphates and arsenates. . 2. A substrate having a step portion formed on the surface thereof,
Semiconductor comprising a step of covering the step portion with an organic resin to form an interlayer insulating film on the substrate, and a step of flattening the interlayer insulating film by polishing with a polishing slurry. A method for manufacturing a device, wherein, as the organic resin, polyimide, polytetrafluoroethylene, polysiloxane, fluorinated silicate, fluorinated polyimide, polymer having pores, polycarbonate polysiloxane, parylene compound One or two or more of the above are used, and as the polishing slurry, a slurry in which water-soluble inorganic compound fine particles are dispersed in a non-aqueous dispersion medium is used. 3. The water-soluble inorganic compound fine particles are carbonates, sulfates, nitrates, ammonium salts of metal ions, halogen compounds, perchlorates, silicates, borates, phosphates, and arsenates. 3. The method for manufacturing a semiconductor device according to claim 2 , wherein the method comprises one or more of the above.