JPH11172418A - Film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film forming device in which the quantity of raw material monomers to be fed into a treating chamber for vapor depositing polymerization is correctly regulated to form a high molecular film having uniform coating thickness. SOLUTION: This device has plural treating chambers 4 to 6 for executing film forming treatment to a substrate 8. The primary treating chamber 4 is the one of vapor depositing polymerization, and as for raw material monomers A and B to be used for the vapor depositing polymerization, the quantity to be fed is regulated in a liq. state by liq. flow rate controllers 47A and 47B, and they are vaporized by vaporizers 48A and 48B and are introduced into the primary treating chamber 4. In the primary treating chamber 4, a high molecular film is formed on the substrate 8 by a depo-down system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for forming a low dielectric constant polymer film used as an interlayer insulating film of a semiconductor device by vapor deposition polymerization.

[0002]

2. Description of the Related Art Conventionally, as an interlayer insulating film of a semiconductor device, an SOG (Spin on Glass) film or a CV
An SiO ₂ film formed by a D method (Chemical Vapor Deposition) is mainly used. The relative dielectric constant of the interlayer insulating film formed by these methods is about 4,
Recently, with the progress of high integration of LSIs, it has been considered that the reduction of the relative dielectric constant of the interlayer insulating film is a major issue, and an interlayer insulating film having a relative dielectric constant of 4 or less has been required.

In response to such a demand, a SiOF film in which fluorine is added to an SiO ₂ film formed by a plasma CVD method has recently been proposed. According to this film, the relative dielectric constant of an interlayer insulating film is reduced. It can be suppressed to about 3.7 to 3.2.

Also, an amorphous fluorocarbon film has been proposed as a low dielectric constant interlayer insulating film. According to this film, the relative dielectric constant of the interlayer insulating film can be suppressed to about 2.7 to 2.3. it can.

However, S by plasma CVD
While the iOF film can achieve a low relative dielectric constant, the film characteristics vary greatly depending on the film formation method and film formation conditions, and the dielectric constant due to film instability such as desorption of fluorine in the film and large hygroscopicity. It has been pointed out that the problem of exacerbating the problem is that it is difficult to apply it as a low dielectric constant material in the future.

[0006] Even in the case of an amorphous fluorocarbon film, the film characteristics greatly differ depending on the method of forming the film and the film forming conditions, and it is necessary to sacrifice the heat resistance in order to achieve a low dielectric constant. For this reason, when heated at about 400 ° C. in a process other than the formation of the interlayer insulating film, a gas is easily generated due to the decomposition of the film, and when a film is formed on the interlayer insulating film, a gas is generated between these films and the device is mounted. It has been pointed out that this can be a destructive factor.

On the other hand, according to the study of the present inventors, various polymer films produced by the vapor deposition polymerization method can realize a dielectric constant of 2.5 or less, thereby having stable characteristics without the above-mentioned disadvantages. It has also been found that an interlayer insulating film can be obtained.

Conventionally, in the vapor deposition polymerization method, the vapor of the raw material monomer is always supplied from below the substrate in a processing chamber in which the evaporation source is located below the substrate due to its structural easiness. As a result, a film is formed.

[0009]

However, in the process of manufacturing a semiconductor device, since a film is formed by a general deposition method, a film formed by a vapor deposition polymerization method is used as an interlayer insulating film of the semiconductor device. However, there is a problem that the substrate must be turned upside down during the manufacturing process, which complicates the manufacturing process.

In order to solve such a problem, an evaporation source may be provided outside the processing chamber, and vaporization polymerization may be performed by a deposition-down method by supplying vapor of a raw material monomer from an upper portion of the processing chamber. Conceivable.

However, in the case of vapor deposition polymerization, the raw material monomers usually evaporate at a temperature of 100 ° C. or higher, and have a large molecular weight. It is difficult to precisely control the amount of raw monomer vapor supplied,
There is a problem that the thickness of the polymer film tends to be uneven.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and precisely controls the supply amount of a raw material monomer into a processing chamber for vapor deposition polymerization to achieve a uniform film thickness. It is an object to provide a film forming apparatus capable of forming a molecular film.

[0013]

According to an aspect of the present invention, there is provided a film forming apparatus having a plurality of processing chambers for performing a film forming process on a substrate. At least one of the plurality of processing chambers is a processing chamber for vapor deposition polymerization, and a supply amount control unit that controls a supply amount of the liquid raw material monomer used for the vapor deposition polymerization, Vaporizing means for vaporizing a predetermined amount of a liquid raw material monomer introduced into the processing chamber for vapor deposition polymerization.

In the case of the first aspect of the present invention, since the amount of the raw material monomer supplied into the processing chamber for vapor deposition polymerization is controlled in a liquid state, the supply amount of the raw material monomer is controlled in a gaseous state. The amount of the raw material monomer supplied into the processing chamber can be accurately controlled as compared with the related art in which the control is performed, whereby a polymer film having a uniform film thickness can be formed.

In this case, as in the second aspect of the present invention,
In the first aspect of the invention, it is also effective that the supply source for supplying the raw material monomer is provided outside the processing chamber for vapor deposition polymerization.

According to the second aspect of the present invention, the processing chamber for vapor deposition polymerization can be made small, and a part of the monomer does not adhere around the supply source.
Cleaning work becomes easy. Further, it is not necessary to consider the influence of heat on the substrate due to the heating of the monomer.

For the same reason, it is also effective to provide the above-described supply amount control means and vaporization means outside the processing chamber.

According to a third aspect of the present invention, in the first aspect of the present invention, the processing chamber for vapor deposition polymerization supplies the raw material monomer to the substrate from above. Is also effective.

According to the third aspect of the present invention, it is not necessary to turn the substrate over when forming the interlayer insulating film in the manufacturing process of the semiconductor device, so that the manufacturing process can be simplified.

[0020]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1A shows a schematic configuration of an example of a film forming apparatus according to the present invention. As shown in FIG. 1A, the film forming apparatus 1 is a multi-chamber type single-wafer apparatus, and a Si chamber is provided around a core chamber 2 in which a transfer robot (not shown) is installed.
L / UL for loading and unloading a substrate 8 such as a wafer
(Load / Unload) chamber 3, first processing chamber 4 for performing vapor deposition polymerization, second processing chamber 5 for performing heat treatment, and third processing for performing sputtering of aluminum or the like. A chamber 6 is arranged, and these are all connected via a gate valve (not shown).

The core chamber 2, the L / UL chamber 3, and the first to third processing chambers 4 to 6 are connected to a vacuum exhaust system such as a vacuum pump (not shown). Further, the substrate 8 can be freely transferred from the L / UL chamber 3 to the first to third processing chambers 4 to 6 by a robot arranged in the core chamber 2.

FIG. 1 (b) shows a schematic configuration of the first processing chamber 4 of the film forming apparatus 1 shown in FIG. 1 (a). FIG.
As shown in (b), above the first processing chamber 4, supply sources 40A and 40B of two kinds of raw material monomers A and B are connected via introduction pipes 41A and 41B. Each source 4
The housings 42A and 42B of the housings 0A and 40B are provided with monomer containers 43A and 43B, respectively. And
For example, raw material monomers A and B for forming a polyimide film are injected into the monomer containers 43A and 43B, respectively.

In this case, as raw material monomers A and B,
For example, 4,4'-diaminodiphenyl ether (ODA) or the like is used as a diamine monomer, and pyromellitic dianhydride (PMDA) or the like is used as an acid component monomer.
These raw material monomers A and B are dissolved in an organic solvent such as acetone at a concentration of about 1 mol / l.

In the case of the present embodiment, each of the monomer containers 43A and 43B is connected to an inert gas source (not shown) via each of the gas introduction pipes 44A and 44B. With such a configuration, an inert gas such as nitrogen (N ₂ ) gas pressurized to a certain pressure (about 100 Pa) is introduced into each of the monomer containers 43A and 43B. This inert gas is supplied to the monomer containers 43A and 43A.
The inside of B is set to a pressure higher than the vapor pressure of the organic solvent of the starting monomers A and B, and the starting monomers A and B are introduced into the introduction pipes 41A and
1B.

On the other hand, a heater 45 is wound around each of the introduction pipes 41A and 41B so that the temperature of the raw material monomers A and B can be controlled. Valves 46A, 46B for controlling the supply of the raw material monomers A, B are provided in the middle of each of the introduction pipes 41A, 41B.
Are provided, and monomer containers 43A and 43B and valves 46A and 46B are provided in the middle of each of the introduction pipes 41A and 41B.
And a liquid flow controller (supply amount control means) 4 for controlling the flow amount (liquid amount) of each of the raw material monomers A and B.
7A and 47B are provided. These valves 46A, 46B and the liquid flow controllers 47A, 47
By simultaneously turning B on and off, the film thickness can be controlled during the formation of the vapor-deposited polymer film.

Further, a vaporizer (vaporizing means) for heating and vaporizing each of the raw material monomers A and B is provided between the valves 46A and 46B and a mixing tank 4b described later in the middle of each of the introduction pipes 41A and 41B. 48A and 48B are provided.

As shown in FIG. 1B, the first processing chamber 4
Is a processing tank 4 a for performing a film forming process on the substrate 8.
And a mixing tank 4b formed integrally and airtightly at the upper part of the processing tank 4a and extending downward. Here, the substrate 8 is located below the processing tank 4a.
A hot plate 4c for heating is provided. On the other hand, on the inner wall of the mixing tank 4b, each raw material monomer A,
A heater 49 for heating and diffusing the B vapor is provided.

FIG. 2 (a) shows a schematic configuration of the second processing chamber 5 of the film forming apparatus 1 of FIG. 1 (a). FIG.
As shown in (a), a hot plate 50 for heating the substrate 8 is provided in the second processing chamber 5.
The hot plate 50 is configured so that the temperature of the substrate 8 can be controlled in a wider range (20 to 500 ° C.) than the temperature at the time of manufacturing the semiconductor device, and the heating rate during heating can be adjusted. I have.

FIG. 2 (b) shows a schematic configuration of the third processing chamber 6 of the film forming apparatus 1 of FIG. 1 (a). FIG.
As shown in (b), a DC bipolar sputtering device is provided in the third processing chamber 6. That is, the electrode 61 connected to the DC power supply 60 is provided above the third processing chamber 6.
The electrode 61 holds, for example, an aluminum target as a sputtering target 62. The substrate 8 to be processed is supported by a hot plate 63 at the lower part of the third processing chamber 6. In addition, an inert gas such as an argon (Ar) gas is introduced into the third processing chamber 6 through an introduction pipe 64.

To form an insulating film in this embodiment, first, in the film forming apparatus 1, the substrate 8 is
Transported from the chamber 3 into the first processing chamber 4 and each valve 46A,
46B is opened, the raw material monomers A and B are introduced into the first processing chamber 4, and a polyamic acid film is formed on the substrate 8 by vapor deposition polymerization described below. In this case, first, the pressure in the first processing chamber 4 is set to a high vacuum of about 3 × 10 ⁻³ Pa with the valves 46A and 46B closed.

Then, the valves 46A and 46B are opened, and the liquid flow controllers 47A and 47B are driven to drive a certain amount (for example, about 10 ml / min) of the raw material monomers A and B.
To the vaporizers 48A and 48B. Vaporizer 48A, 4
In 8B, the raw material monomers A and B are heated to a predetermined temperature to evaporate, and vapors of the raw material monomers A and B are introduced from the upper part of the mixing tank 4b of the first processing chamber 4.

In this way, the raw monomers A and B are deposited and deposited on the substrate 8 to form a polyamic acid film, and then the valves 46A and 46B are closed. In this case, the evaporation rates of the raw material monomers A and B are controlled so as to have a stoichiometric ratio of 1: 1.

Thereafter, in the second processing chamber 5, the substrate 8
A predetermined heat treatment is performed on the upper polyamic acid film using a hot plate 50.

In this case, the heating condition is a heating rate of 5 ° C./m
The temperature is raised to about 400 ° C. in this state, and the state is maintained for about 60 minutes. This heat treatment is performed, for example, in a vacuum.

If necessary, the substrate 8 can be transferred to the third processing chamber 6 and an aluminum electrode can be formed on the substrate 8 by sputtering.

As described above, according to the present embodiment,
A low dielectric constant polyimide film having stable characteristics can be obtained by a simple process.

Particularly, in the case of the present embodiment, since the supply amounts of the raw material monomers A and B supplied into the first processing chamber 4 are controlled in a liquid state, the raw material monomers A and B are controlled.
Compared with the prior art, which controls the supply amount of gas in a gaseous state.
In this case, the supply amounts of the raw material monomers A and B into the processing chamber 4 can be accurately controlled, and a polyimide film having a uniform film thickness can be formed.

In this embodiment, the supply sources 40A and 40B of the raw monomers A and B, the liquid flow controllers 47A and 47B, and the vaporizers 48A and 48B are provided outside the first processing chamber 4. Therefore, the first processing chamber 4
Can be made small, and a part of the raw material monomers A, B does not adhere to the periphery of the supply sources 40A, 40B, etc., so that the cleaning operation is also easy. Another advantage is that it is not necessary to consider the influence of heat on the substrate 8 due to the heating of the raw material monomers A and B.

FIGS. 3A to 3F show an example of a process for forming an interlayer insulating film of a semiconductor device by using the present invention. First, for example, as shown in FIG.
i), a silicon thermal oxide film 22 formed on the surface of the semiconductor substrate 21 and having a window formed at a predetermined position, and a first layer formed on the silicon oxide film and patterned. Substrate 3 having wiring (metal wiring layer) 23
Prepare 1

While heating the substrate 31 to a predetermined temperature,
A polyamic acid film 24a is formed on the entire surface of the substrate 31 to a desired thickness by the above-described vapor deposition polymerization method (FIG. 3B).

Further, heat treatment (imidization treatment) is performed under the above conditions to form an interlayer insulating film 24 made of polyimide having high heat resistance (FIG. 3C).

Next, on the surface of the interlayer insulating film 24, a resist film 25 having been subjected to a predetermined patterning by a resist process is formed (FIG. 3D), and the resist film 25 is dry-etched. The interlayer insulating film 24 exposed at the window opening is removed (FIG. 3E). After removing the resist film 25, a wiring thin film is formed on the entire surface and patterned to form a second-layer wiring (metal wiring layer).

As a result, the first-layer wiring 23 and the second-layer wiring 26 are electrically connected to each other at the window opening portion 27 from which the interlayer insulating film 24 has been removed. The device 35 can be obtained (FIG. 3
(f)).

According to the present embodiment, a semiconductor device 35 having stable characteristics can be obtained by simple steps using only a vacuum process.

In particular, in the case of the present embodiment, it is not necessary to turn the substrate 31 upside down when forming the interlayer insulating film 24, so that the manufacturing process can be simplified.

Further, according to the present embodiment, it is possible to form the interlayer insulating film 24 having a uniform film thickness and a constant relative dielectric constant, thereby obtaining a semiconductor device 35 having a constant operation speed. .

Note that the present invention is not limited to the above-described embodiment, and various changes can be made. For example,
Ultraviolet rays can be applied to the polyimide film formed by vapor deposition polymerization. This makes it possible to further improve the heat resistance of the polyimide film.

Further, the present invention can be applied not only to an interlayer insulating film of a semiconductor device but also to various insulating films. However, the present invention is more effective when applied to an interlayer insulating film of a semiconductor device.

[0049]

EXAMPLES Hereinafter, specific examples of the present invention will be described together with comparative examples. A polyimide film was formed on the substrate 8 using the film forming apparatus 1 shown in FIGS.

First, a 6-inch size having a conductivity of 0.02
A substrate 8 made of (Ω · cm) silicon (Si) is carried into the first processing chamber 4 and placed on the hot plate 4c.
A polyamic acid film is formed on the substrate 8 by vapor deposition polymerization. In this case, as the raw material monomers A and B, an acetone solution of ODA and PMDA (concentration: 1 mol / l) was used.

After the pressure in the first processing chamber 4 is set to a high vacuum of about 3 × 10 ⁻³ Pa with the valves 46A and 46B closed, the valves 46A and 46B are opened and the liquid flow controller is opened. 47A and 47B are driven to feed a certain amount (10 ml / min) of the raw material monomers A and B into the vaporizer 4.
8A and 48B. In the vaporizers 48A and 48B, ODA and PMDA are heated to a predetermined temperature to evaporate, and ODA and PDA are evaporated from the upper part of the mixing tank 4b of the first processing chamber 4.
MDA steam is introduced. In this case, ODA and PMDA
Was controlled such that the stoichiometric ratio in the film became 1: 1.

In this manner, the ODA and the PMD
After depositing and depositing A to form a polyamic acid film, the valves 46A and 46B are closed.

After that, the substrate 8 was carried into the second processing chamber 5 through the core chamber 2, and a predetermined heat treatment (imidization treatment) was performed on the polyamic acid film.

In this case, the conditions for the heat treatment are as follows:
Heat to 350 ° C at a temperature of 350 ° C / min.
Hold for minutes. At this point, the thickness of the polyimide film was 500 nm.

The above process was repeated ten times to obtain ten pieces of polyimide film materials. When the film thickness was measured for each of these examples, the respective film thicknesses were almost the same (average between batches ± 2%).

When the infrared absorption spectrum of each example was measured, exactly the same spectrum was obtained.

On the other hand, as a comparative example, a polyimide film was formed 10 times on the substrate 8 by the same method as that of the embodiment except that a conventional evaporation source in which the raw material monomers A and B were heated by a heater was used. You got the material.

When the infrared absorption spectrum of each comparative example was measured, exactly the same spectrum was obtained, but the dispersion of the film thickness was large (average between batches ±
8%), and the thickness of the polyimide film tended to decrease as the film formation was repeated.

As is clear from the above Examples and Comparative Examples, according to the present invention, the supply amounts of the raw material monomers A and B into the first processing chamber 4 could be controlled accurately.

[0060]

As described above, according to the present invention, it is possible to accurately control the supply amount of the raw material monomer into the processing chamber for vapor deposition polymerization, and to form a polymer film having a uniform film thickness. Can be. Further, by forming an interlayer insulating film of a multi-layered wiring semiconductor device according to the present invention, an interlayer insulating film having a uniform thickness and a constant relative dielectric constant can be efficiently formed, and as a result, the operation speed can be kept constant. A semiconductor device can be manufactured efficiently.

[Brief description of the drawings]

FIG. 1 (a): Schematic configuration of an example of a film forming apparatus for carrying out the present invention (b): Schematic configuration of a first processing chamber in the film forming apparatus of FIG. 1 (a)

2 (a): Schematic configuration of a second processing chamber in the film forming apparatus of FIG. 1 (a). (B): Schematic configuration of a third processing chamber in the film forming apparatus of FIG. 1 (a).

FIGS. 3A to 3F are process diagrams showing an example of a process of forming an interlayer insulating film of a semiconductor device using the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Film-forming apparatus 2 ... Core room 3 ... L / UL room 4 ... 1st
Processing chamber 4a Processing tank 4b Mixing tank 4c Hot plate 5 Second processing chamber 6 Third processing chamber 8 Substrate (base) 21 Semiconductor substrate 22 Silicon thermal oxide film 23 First layer Eye wiring 24 ... Interlayer insulating film
24a ... polyamic acid film 25 ... resist film 26 ... second-layer wiring (metal wiring tank) 31 ... substrate 35 ... semiconductor device A, B ... raw material monomer 40A, 40B ... supply source 41A, 41B ... introduction tube 46A, 46B ... Valves 47A, 47B ... Liquid flow rate controller (supply amount control means) 48A, 48B ... Vaporizer (vaporization means) 49 ...
heater

Claims (3)

[Claims] 1. A film forming apparatus having a plurality of processing chambers for performing a film forming process on a substrate, wherein at least one of the plurality of processing chambers is a processing chamber for vapor deposition polymerization. Supply amount control means for controlling the supply amount of the liquid raw material monomer used for vapor deposition polymerization, and a predetermined amount of the liquid raw material monomer introduced into the processing chamber for vapor deposition polymerization via the supply amount control means A film forming apparatus comprising: 2. A film forming apparatus according to claim 1, wherein a supply source for supplying a raw material monomer is provided outside a processing chamber for vapor deposition polymerization. 3. The film forming apparatus according to claim 1, wherein the processing chamber for vapor deposition polymerization is configured to supply a raw material monomer to the substrate from above. .