JPH05283541A - Formation of interlayer insulation film - Google Patents

Abstract

PURPOSE:To realize formation of interlayer insulation film employing solution growth method for preventing adhesion of a film to the inner wall of reaction vessel. CONSTITUTION:O-xylene (melting point 145 deg.C) is filled in a reaction vessel 21 and held at a temperature of 145 deg.C by means of a heater 29 thus removing water content. It is then added with an organic metal alkoxide, e.g. trimethylmethoxysilane, and recirculated at 146 deg.C to cause reaction to hydroxy group on the surface of inner wall of the reaction vessel thus completing hydrophobic processing. An interlayer insulation film is then grown on a wafer 27. Since a film is prevented from adhering to the inner wall of vessel, the interlayer insulation film is grown at a stabilized rate resulting in a high quality film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an interlayer insulating film adapted to the field of manufacturing semiconductor devices, and more particularly to a method for favorably forming a planarizing insulating film formed by a so-called solution growth method.

[0002]

2. Description of the Related Art In recent years, wiring technology has been progressing toward miniaturization and multi-layering as the device density has increased.

On the other hand, the progress of high integration in this way results in a decrease in reliability. This is because the step of the interlayer insulating film is
This is because it becomes large and steep, and the processing accuracy and reliability of the wiring formed thereon are reduced. Therefore, A
Currently, it is necessary to improve the flatness of the interlayer flattening film, which cannot significantly improve the step coverage of the 1-wiring.

Conventionally, as a technique for forming and planarizing this type of insulating film, for example, CV using an organic silane-based gas has been used.
D method, bias sputtering and bias ECR CVD technology for forming an angle by performing sputter etching simultaneously with film formation, flattening technology for applying SOG (Spin On Glass), flattening technology for softening the film by heat treatment,
Various etch back methods are known.

However, when applied to miniaturized and multi-layered wiring layers, there is a serious problem such as poor connection between wirings due to lack of flatness in a place where wiring spacing is wide and generation of voids in the interlayer film at the wiring spacing. It has become.

Therefore, as a means for improving this problem, A
A technique for flattening an Al wiring layer having a high aspect ratio by selectively forming an insulating film between the wirings (Japanese Patent Application No.
Invention related to No. 300447) has been proposed. As a means for such selective growth, a mask is formed on the Al wiring, and then an organic metal alkoxide is reacted in a nonaqueous solvent to form an interlayer insulating film (solution growth method).

Further, as a technique for improving this type of solution growth method, a technique according to Japanese Patent Application No. 3-254003 is known.

[0008]

However, such a solution growth method is attracting attention as an effective interlayer flattening method from the viewpoints that the process temperature can be lowered and the apparatus is simple. Since the reaction mechanism uses the dehydration condensation reaction with the surface hydroxyl groups, reaction products are deposited on the surfaces of the metal and the quartz constituting the reaction container in addition to the surface of the wafer, so that the generation of particles and the fluctuation of the film formation rate may occur. However, a stable interlayer insulating film could not be formed.

Further, although a hydrophobic treatment such as a fluororesin coating may be considered depending on the constituent materials, its use is limited because pinholes are generated and the coating itself is difficult depending on the material.

The present invention was devised by focusing on such conventional problems, and is provided with a treatment for preventing the reaction product from adhering to a container, which can withstand a solution reaction treatment for a long time. An object of the present invention is to obtain a method for forming an interlayer insulating film having good film controllability.

[0011]

That is, according to the present invention, in the insulating film forming step by the solution reaction method, the surface hydroxyl group is substituted for the purpose of preventing adhesion of the insulating film in the reaction vessel prior to forming the insulating film by the solution reaction. The compound is characterized in that the treatment is carried out using an organometallic alkoxide containing at least one or more alkyl groups or fluorine-containing alkyl groups.

[0012]

In the surface treatment method according to the invention of the present application, the hydroxyl group on the inner wall surface of the reaction vessel is fixed with an alkyl group on the surface by means of solution reactivity with, for example, trimethylmethoxysilane. Therefore, by substituting the surface hydroxyl group with an alkyl group, it is possible to prevent the organic metal alkoxide from adhering to the inner wall of the reaction vessel during the solution reaction, suppress the generation of particles, and form a stable interlayer flattening insulating layer.

[0013]

EXAMPLES Specific examples of the present invention will be described below. Before explaining the actual surface treatment process,
First, a configuration example of a solution reaction apparatus used for carrying out the present invention and a processing method will be described with reference to FIG.

Here, a single-plate type reaction processing apparatus is taken as the solution reaction apparatus, but the structure of the wafer mounting method and the usage method are not particularly limited.

An inlet pipe 22 for introducing a necessary treating agent in the direction of arrow B1 and an inlet pipe 23 for introducing a solvent in the direction of arrow B2 are provided on one side wall of the reaction vessel 21. Further, on the other side wall portion, a trap 24 for separating surface adsorbed water, by-products and the like at the time of solution reaction and a chiller 26 embedded in a cooling pipe 25 for enabling the reflux of the solvent and arranged outside the apparatus are provided. The refrigerant is introduced from the cooling equipment and circulated in the direction of arrow C1 in the figure. A reaction vessel 21 made of quartz contains a mounting table 28 on which a wafer 27 as a substrate to be processed is placed, and a heater 29 for heating a solution is embedded in the reaction vessel.

Further, an exhaust device 30 is connected to the trap 24 so that the pressure inside the reaction vessel can be controlled. Next, an actual process example of the surface treatment method using the reaction container having such a configuration will be described.

(Embodiment 1) In this embodiment, the present invention is applied to a process in which Al wiring layers are flattened.

First, prior to the formation of the interlayer flattening insulating film, the surface hydroxyl group is replaced with a hydrophobic functional group for the purpose of preventing the insulating film from adhering to the inside of the reaction vessel as follows.

A hydrophobic solvent such as orthoxylene (O-xylene boiling point 145 ° C.) is introduced into the reaction vessel 21. At this time, the temperature of the solvent is kept at 145 ° C., which is the boiling point, by the heater 29. At this time, the water adsorbed on the side wall in the reaction vessel 21 is evaporated together with the added solvent and liquefied in the cooling pipe 25 described above. At this time, the adsorbed water that is incompatible with orthoxylene is separated into the trap 24 due to the difference in specific gravity. In this state, the adsorbed water is refluxed for about 1 hour until it is completely desorbed. When surface-adsorbed water remains, particles are generated due to reaction of organic metal alkoxide such as trimethylmethoxysilane added in the next hydrophobic surface formation in the solvent, and the effect of hydrophobic treatment is insufficient. The harmful effect of will occur.

Next, after the adsorbed water in the trap 24 is removed from the drain, trimethylmethoxysilane, which is an organometallic alkoxide containing three alkyl groups (methyl groups), is added and the mixture is refluxed at 146 ° C. to form an inner wall of the reaction vessel. By reacting with the hydroxyl groups on the surface, the hydrophobic treatment is performed and the surface treatment is completed.

Thereafter, tetraethoxysilane is added to the ortho-xylene solution in the same manner as in the conventional case, and the wafer is refluxed in the solution to complete the formation of the interlayer flattening insulating film.

As the solvent used in the surface treatment method using the solvent reaction, a solvent which is a hydrophobic solvent and has a boiling point higher than that of the reaction product alcohol (methanol) and surface adsorbed water may be selected. For example, cyclooctane and the like can be considered in addition to orthoxylene.

Although trimethylmethoxysilane was used for forming the interlayer insulating film, any organic metal alkoxide having a functional group that can be expected to have a hydrophobic effect on the surface can be appropriately changed. When the “bulky” alkyl group having a large molecular weight is used as the functional alkyl group, the number of molecules of the surface treatment agent that reacts with the hydroxyl group on the surface is limited due to steric hindrance of the alkyl group. The effect decreases. Therefore, the molecular structure of the alkyl group needs to be determined in consideration of the amount of surface hydroxyl groups.

(Embodiment 2) This embodiment is characterized in that the pressure is lowered in the hydrophobic treatment step in order to effectively remove the reaction by-product in the surface treatment method. Even if a solvent having a high boiling point is used, the solvent can be refluxed at a low temperature, the difference in boiling point temperature with the adsorbed water can be increased, and an effective hydrophobic surface treatment can be performed.

A hydrophobic solvent such as cyclooctanone is introduced into the reaction vessel 21. The boiling point of the solvent is lowered by maintaining the pressure in the reaction vessel 21 at 3990 [Pa] (30 [torr]). At this time, the heater 29
The temperature of the solvent is kept at 70 ° C., which is the boiling point. The water adsorbed on the inner wall of the reaction vessel 21 evaporates together with the added solvent and is liquefied in the cooler 25 described above.

Adsorbed water that is incompatible with cyclooctanone is separated into traps 24 due to the difference in specific gravity. In this state, reflux is performed for about 1 hour until the adsorbed water is completely desorbed. Next, after removing the adsorbed water in the trap 24 from the drain,
At least one or more of trifluoromethylmethoxysilane, which is an organic metal alkoxide containing an alkyl group containing fluorine, is added to obtain 3990 [Pa] (30 [tor
r]) and then reflux at 70 ° C. to react with the hydroxyl groups on the surface of the reaction vessel 21 to complete the surface treatment. After that, tetraethoxysilane is added to the orthoxylene solution in the same manner as in Example 1 above, and the wafer is refluxed in the solution to complete the formation of the interlayer flattening insulating film.

The first and second embodiments have been described above.
The present invention is not limited to these, and various changes accompanying the gist of the configuration are possible, and various organic metal alkoxides can be applied.

[0028]

As is apparent from the above description, according to the present invention, it is possible to prevent the film from adhering to the surface of the inner wall of the reaction container, to stabilize the deposition rate of the interlayer insulating film, and This has the effect of forming an insulating film.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a solution reaction processing apparatus used in an example of the present invention.

[Explanation of symbols]

 21 ... Reaction vessel

Claims (2)

[Claims] 1. A method for forming an interlayer insulating film, wherein a growth substrate is placed in a reaction container, and an insulating film is grown on the growth substrate by a condensation reaction of an organic silicon compound in the reaction container. A method for forming an interlayer insulating film, characterized in that, before the step of growing the film, the surface of the inner wall of the reaction vessel is subjected to a hydrophobizing treatment using an organic metal alkoxide containing at least one or more alkyl groups. 2. A method for forming an interlayer insulating film, wherein a growth substrate is placed in a reaction container, and an insulating film is grown on the growth substrate by a condensation reaction of an organic silicon compound in the reaction container. Prior to the step of growing a film, the surface of the inner wall of the reaction vessel is subjected to a hydrophobic treatment using at least one or more organometallic alkoxide containing an alkyl group containing fluorine, thereby forming an interlayer insulating film. Method.