JPH09205087A - Deposition of insulation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for depositing an insulation film in which high planarity can be attained by burying level difference on the surface of substrate without increasing the thickness of insulation film while simplifying the process. SOLUTION: When a level difference on the surface of a substrate 11 due to interconnection 12 is buried by forming an interlayer insulation film 13 of fluid material, an interlayer insulation film 13 is deposited by repeating the step a plurality of times. After formation of at least first interlayer insulation film 13, plasma processing is performed in order to eliminate fluidity at least from the surface layer thereof and then another interlayer insulation film 13 is deposited thereon.

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 insulating film, and more particularly to a method for forming an insulating film using a fluid material.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, a method of forming an interlayer insulating film using a fluid material is often used in order to fill a step on the surface of a substrate due to wiring or the like to obtain high flatness. Conventionally, an interlayer insulating film using such a raw material having fluidity has usually been formed at one time to a desired film thickness (for example, 1995 Dry Process Sym.
posium, pp.261-268).

[0003]

However, in the above-described conventional method for forming an interlayer insulating film, in order to fill a step due to wiring or the like and obtain high flatness, the interlayer insulating film is formed using a fluid material. After forming a thick film, it is common to etch back to remove unnecessary portions of the interlayer insulating film. Therefore, it takes time to form the interlayer insulating film, and the process is complicated. Therefore, an object of the present invention is to provide a method for forming an insulating film, which can fill a step on one main surface of a substrate to obtain a high flatness without forming the insulating film thick and has a simple process. .

[0004]

In order to achieve the above object, the present invention fills a step by forming an insulating film using a fluid material on a substrate having a step on one main surface. In the method of forming an insulating film described above, the insulating film is formed in a plurality of times, the insulating film is formed at least the first time, and then the process of removing the fluidity of at least the surface layer of the insulating film is performed. It is a feature.

In the present invention, how many times the insulating film is formed can be determined as necessary.
From the viewpoint of easily forming the insulating film, it is preferably formed in two steps. Further, from the viewpoint of improving the film quality of the insulating film and preventing the occurrence of cracks particularly near the edge of the step, it is desirable that the insulating film be formed many times. In the present invention, the thickness of the insulating film formed first is preferably from the viewpoint of obtaining high flatness.
Considering the film thickness when this insulating film is formed on a flat surface, it is 30 to 70% of the height of the step.

In an exemplary embodiment of the invention, the fluid feedstock is silanol (Si (O
H) ₄ ) as a main component, and an insulating film is formed by polymerization of this silanol on the substrate. In the present invention, the treatment for eliminating fluidity is preferably plasma treatment,
The fluidity may be eliminated by heating the substrate or holding the substrate in a vacuum to remove moisture in the insulating film.

In the present invention, when the treatment for eliminating the fluidity is plasma treatment, the plasma treatment is used to cure and insulate at least the surface layer of the insulating film by using the impact effect of the ions in the plasma. Water in the film is removed at the same time. Also, in this case, preferably,
The wettability of the surface of the insulating film after the plasma treatment is equal to or higher than the wettability of the surface of the insulating film before the plasma treatment. In other words, the wettability of the surface of the insulating film is preferably maintained even after the plasma treatment,
Try to improve.

In a typical embodiment of the present invention, the insulating film is made of an oxide, and at least one kind of gas made of molecules containing oxygen as a constituent atom is used as a reaction gas used for plasma treatment. In one embodiment of the present invention, after the insulating film is formed in the container for forming the insulating film, the process of continuously eliminating the fluidity is performed in the container. In another embodiment of the present invention, after the insulating film is formed in the container for forming the insulating film, the substrate is transferred into a container for processing for eliminating fluidity, and the substrate for processing for eliminating this fluidity is used. Perform a process to eliminate fluidity in the container. In the present invention, typically, the step on one main surface of the substrate is due to the wiring, and the insulating film is an interlayer insulating film formed on this wiring.

According to the insulating film forming method of the present invention configured as described above, a higher degree of flatness can be obtained as compared with the conventional insulating film forming method without forming the insulating film thick. That is, in the conventional method of forming an insulating film, when an insulating film having a desired film thickness is formed on a substrate at one time by using a fluid material, the surface tension of the insulating film causes a step difference on one main surface of the substrate. Inevitably, a recess is formed on the surface of the insulating film, and the flatness deteriorates. On the other hand, in the method for forming an insulating film according to the present invention, the insulating film is formed in a plurality of times, the insulating film is formed at least the first time to fill the step to some extent, and then at least the surface layer of the insulating film is formed. Since the process of eliminating the fluidity of the insulating film is performed, the slope of the step portion when the insulating film is formed for the second time becomes more gradual, so that the flatness after forming the insulating film is more improved. Get higher Moreover, in this case, it is not necessary to perform etch back unlike the conventional insulating film forming method.

Further, by using the plasma treatment for the treatment for eliminating the fluidity, not only the curing of at least the surface layer of the insulating film but also the removal of water in the insulating film can be carried out at the same time. Further, when the insulating film is made of an oxide, by using at least one kind of gas composed of molecules containing oxygen as a constituent atom as a reaction gas used for plasma treatment, the film quality of the insulating film, specifically electrical Improving properties and chemical properties can be done simultaneously. Furthermore, after the insulating film is formed in the container for forming the insulating film, the process of continuously eliminating the fluidity in the container is performed, which is equivalent to the case where the insulating film is formed to a desired film thickness at once. The insulating film can be formed in that time.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, a multi-chamber type processing apparatus used for forming an interlayer insulating film in the following embodiments will be described. FIG. 1 shows this processing device.

As shown in FIG. 1, this processing apparatus comprises a load lock chamber 1, a substrate loading chamber 2, a low pressure CVD chamber 3, another low pressure CVD chamber 4, a plasma processing chamber 5 and a substrate unloading chamber. It has a chamber 6. Here, the substrate loading chamber 2, the low pressure CVD chamber 3, the plasma CVD chamber 4, the plasma processing chamber 5 and the substrate removal chamber 6 are connected to the load lock chamber 1. The substrate loading chamber 2, the reduced pressure CVD chamber 3, the plasma CVD chamber 4, the plasma processing chamber 5 and the substrate removal chamber 6 can be evacuated by a vacuum exhaust device (not shown). There is. Then, through the load lock chamber 1, the low pressure CVD chamber 3 and the plasma CVD without breaking the vacuum.
The substrate to be processed can be transferred between the processing chamber 4 and the plasma processing chamber 5.
The low pressure CVD chamber 3 is configured so that it can also be used for plasma processing.

Here, for comparison with the embodiments described below, an interlayer insulating film having a desired film thickness is formed at one time to fill a step on one main surface of the substrate for planarization. A conventional method for forming an interlayer insulating film will be specifically described. FIG. 4 shows a method of forming this conventional interlayer insulating film. Here, as shown in FIG. 4A, when the Al wirings 102 are formed on the Si substrate 101 at predetermined intervals,
A case will be described in which an interlayer insulating film is formed thereon to fill the step due to the Al wiring 102. However, Al wiring 1
The height of 02 is 0.85 μm.

In this conventional method of forming an interlayer insulating film, as shown in FIG. 4B, SiO 2 is formed by a low pressure CVD method.
_An interlayer insulating film 103 composed of _two films is formed. The film forming conditions at this time are SiH ₄ (80 SCCM) and N ₂ (500
SCCM) and H ₂ O ₂ (0.65 g / min) mixed gas was used as a reaction gas (however, H ₂ O ₂ was supplied as a gas at 100 ° C.), the reaction pressure was 850 mTorr,
Substrate temperature is 0 ° C., film formation time is 60 seconds, film thickness is 0.9 μm
It is. This film thickness means the film thickness when the interlayer insulating film 103 is formed on a flat surface (the same applies hereinafter).

Here, the flatness P of the interlayer insulating film 103 is defined as follows. That is, as shown in FIG. 4B, the height of the Al wiring 102 is H, and the interlayer insulating film 103 is
If the difference in the height of the surface irregularities is h, then the flatness P (%)
Is defined by the following equation. P≡ {1- (h / H)} × 100 When the flatness P is defined in this way, when the interlayer insulating film 103 is formed as described above, the wiring interval L = 10 μm
When m, P = 65%.

Based on the above, the method for forming an interlayer insulating film according to the first embodiment of the present invention will be described. Here, as shown in FIG. 2A, the Si substrate 1
A case will be described in which, when the Al wirings 12 are formed on the first wiring layer 1 at predetermined intervals, the interlayer insulating film is formed thereon so that the final film thickness is 0.9 μm. However, A
The height of the l-wiring 12 is 0.85 μm. In the method of forming the interlayer insulating film according to the first embodiment,
First, the Si substrate 11 is placed in the substrate loading chamber 2 of the processing apparatus shown in FIG. 1, the Si substrate 11 is transferred to the low pressure CVD chamber 3 through the load lock chamber 1, and then the low pressure CVD chamber is used. Figure 3 within 3
As shown in B, the interlayer insulating film 13 made of a SiO ₂ film is formed to a thickness of 0.45 μm (final film thickness 50
(Corresponding to%). The film forming conditions at this time are, for example, SiH ₄ (80 SCCM) and N ₂ (500
(SCCM) and H ₂ O ₂ (0.65 g / min) was used as a reaction gas (H ₂ O ₂ was supplied as a gas at 100 ° C.), the reaction pressure was 850 mTorr, the substrate temperature was 0 ° C. The film time is 30 seconds.

Next, the Si substrate 11 on which the interlayer insulating film 13 having a film thickness of 0.45 μm is formed in this manner is transferred into the plasma processing chamber 5 via the load lock chamber 1. Then, in the plasma processing chamber 5, the interlayer insulating film 13 is exposed to oxygen plasma, that is, plasma processing is performed to cure at least the surface layer of the interlayer insulating film 13 so as to eliminate fluidity, and Moisture in the insulating film 13 was reduced, and electrical characteristics and chemical characteristics were improved. The conditions for this plasma treatment are, for example, O ₂ (1500 SCC
A mixed gas of M) and N ₂ (1000 SCCM) was used as a reaction gas, and the chamber pressure was 750 mTorr.
The applied RF power is 500 W and the processing time is 30 seconds.

Next, the Si substrate 11 which has been subjected to the plasma treatment as described above is returned to the inside of the low pressure CVD chamber 3 through the load lock chamber 1 again, and then SiO 2 is formed under the same film forming conditions as described above. Interlayer insulating film 13 consisting of _two films
Is further formed to a film thickness of 0.45 μm, and the interlayer insulating film 13
And the total film thickness is 0.9 μm. After this, the Si substrate 11
Is transferred to the substrate taking-out chamber 6 via the load lock chamber 1, and then the Si substrate 11 is taken out from the substrate taking-out chamber 6. The flatness P of the interlayer insulating film 13 formed as described above is determined by the wiring interval L =
At 10 μm, P = 80%. In addition, the film thickness of 0.
The total time required to form the 9 μm interlayer insulating film 13 was 150 seconds including the transportation time.

As described above, according to the first embodiment, when the final interlayer insulating film 13 having a thickness of 0.9 μm is formed, the formation is performed in two steps. First, the film is formed. After forming the interlayer insulating film 13 having a thickness of 0.45 μm, at least the surface layer is cured by oxygen plasma treatment on the surface to eliminate fluidity, and then the interlayer insulating film 13 is formed again to form a total film thickness. Is 0.9 μm, the flatness P is 15% as compared with the case where the interlayer insulating film 13 having a film thickness of 0.9 μm is formed at once by the conventional method for forming an interlayer insulating film shown in FIG. Can also be higher. Further, since it is not necessary to perform etch back after forming the interlayer insulating film 13, the process is simple.

Next explained is a method for forming an interlayer insulating film according to the second embodiment of the invention. Here, similar to the method of forming the interlayer insulating film according to the first embodiment described above, as shown in FIG. 3A, the Al wiring 1 is formed on the Si substrate 11.
A case will be described in which, when 2 are formed at predetermined intervals, an interlayer insulating film is formed thereon so that the final film thickness is 0.9 μm. Also in this case, the Al wiring 1
The height of 2 is 0.85 μm.

In the method for forming an interlayer insulating film according to the second embodiment, first, a Si substrate 11 is put in a substrate loading chamber 2 of the processing apparatus shown in FIG. After the Si substrate 11 is transferred into the low pressure CVD chamber 3, in the low pressure CVD chamber 3, as shown in FIG. 3B, the interlayer insulating film 13 made of a SiO ₂ film having a thickness of 0.6 μm (final Film thickness of 67%). The film forming conditions at this time are, for example, SiH ₄ (80 SCC
M) and N ₂ (500 SCCM) and H ₂ O ₂ (0.65 g
/ Min) was used as a reaction gas (H ₂ O ₂ was supplied as a gas at 100 ° C.), and the reaction pressure was 850 m.
Torr, the substrate temperature is 0 ° C., and the film formation time is 40 seconds.

Next, of the reaction gas supplied to the low pressure CVD chamber 3, the supply of only SiH ₄ is stopped and the low pressure CVD chamber 3 is supplied with a mixed gas atmosphere of N ₂ and H ₂ O _2. And the chamber pressure is 750 mTo
rr. The time required for this operation is 3 seconds. Next, in the low pressure CVD chamber 3, for example, R of 500 W
By applying F electric power to generate plasma and perform plasma treatment, at least the surface layer of the interlayer insulating film 13 is hardened to eliminate fluidity, and the interlayer insulating film 1
The water content in 3 was reduced, and the electrical and chemical properties were improved.

Next, S in the low pressure CVD chamber 3
The supply of iH ₄ was restarted and the chamber pressure was set to 850 mT.
orr. The time required for this operation is 3 seconds. Next, in the low pressure CVD chamber 3, an interlayer insulating film 13 made of a SiO ₂ film was further formed to a film thickness of 0.30 μm under the same film forming conditions as described above, and the total film thickness of the interlayer insulating film 13 was changed. It is 0.9 μm. After that, the Si substrate 11 is transferred to the substrate taking-out chamber 6 via the load lock chamber 1, and then the Si substrate 11 is taken out from the substrate taking-out chamber 6. The flatness P of the interlayer insulating film 13 formed as described above has a wiring interval L = 10 μm.
At that time, P = 77%. The total time required to form the interlayer insulating film 13 having a film thickness of 0.9 μm was 66 seconds including the carrying time.

As described above, according to the second embodiment, when the final interlayer insulating film 13 having a thickness of 0.9 μm is formed, the formation is performed in two steps. First, the film is formed. After forming the interlayer insulating film 13 having a thickness of 0.6 μm, at least the surface layer of the interlayer insulating film 13 is cured by plasma treatment to remove fluidity, and then the interlayer insulating film 13 is formed again.
To form a total film thickness of 0.9 μm.
Similar to the above embodiment, the flatness P can be significantly improved as compared with the conventional method of forming an interlayer insulating film. Also,
Since it is not necessary to etch back after forming the interlayer insulating film 13, the process is simple. The total time (66 seconds) required to form the interlayer insulating film 13 having a thickness of 0.9 μm in the second embodiment is 0.9 μm when the conventional method for forming an interlayer insulating film shown in FIG. It is almost the same as the total time (60 seconds) required to form the interlayer insulating film. That is, according to the second embodiment, the interlayer insulating film 13 having higher flatness than the conventional one can be formed in the same time as the conventional method for forming an interlayer insulating film.

The embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention. For example, the numerical values, gas species, film types, processes, substrate materials, etc. mentioned in the above-described first and second embodiments are merely examples, and different numerical values, gas species, film Type, process,
A substrate material or the like may be used. Also, if necessary,
The interlayer insulating film may be subjected to a treatment for eliminating fluidity, and then a treatment for making the surface of the interlayer insulating film hydrophilic is performed, and an interlayer insulating film may be further formed thereon. By doing so, it is possible to further increase the flatness. For example, plasma treatment can be used for the treatment for making hydrophilic. The conditions of this plasma treatment are, for example, N ₂ O (2000 SCCM) and N ₂ (10
00SCCM) as a reaction gas, the reaction pressure is 1000 mTorr, and the applied RF power is 500.
W, processing time is 15 seconds. In addition, the treatment for hydrophilization is performed by plasma treatment using appropriate conditions.
It may be performed at the same time as the process of eliminating fluidity. Furthermore, in the above-described first and second embodiments, plasma CV is formed above and below the interlayer insulating film 13, respectively.
It may be form a base layer and a cap layer made of SiO ₂ film formed by D method. Here, in forming the SiO ₂ film by the plasma CVD method, for example, a mixed gas of SiH ₄ and N ₂ O is used as a reaction gas, and the substrate temperature is 350 ° C.

[0026]

As described above, according to the method for forming an insulating film of the present invention, the insulating film is formed in a plurality of times, the insulating film is formed at least in the first time, and then at least the surface of the insulating film is formed. By performing the treatment for eliminating the fluidity of the layer, it is possible to fill the step on the one main surface of the substrate to obtain high flatness without forming the insulating film thick, and the process is simple.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a multi-chamber type processing apparatus used in an embodiment of the present invention.

FIG. 2 is a sectional view for illustrating the method for forming an interlayer insulating film according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating the method for forming an interlayer insulating film according to the second embodiment of the present invention.

FIG. 4 is a sectional view for explaining a conventional method for forming an interlayer insulating film.

[Explanation of symbols]

 11 Si substrate 12 Al wiring 13 Interlayer insulating film

Claims (13)

[Claims] 1. A method for forming an insulating film, wherein an insulating film is formed on a substrate having a step on one main surface using a fluid material to fill the step, and the insulating film is formed a plurality of times. A method for forming an insulating film, characterized in that the insulating film is formed at least once, and then the insulating film is formed at least the first time, and then a treatment for eliminating the fluidity of at least the surface layer of the insulating film is performed. 2. The method for forming an insulating film according to claim 1, wherein the insulating film is formed twice. 3. The film thickness of the insulating film formed at the first time is 30 to 70% of the height of the step in consideration of the film thickness when the insulating film is formed on a flat surface. The method for forming an insulating film according to claim 1, wherein 4. The formation of an insulating film according to claim 1, wherein the fluid material has silanol as a main component, and the insulating film is formed by polymerization of the silanol on the substrate. Method. 5. The method for forming an insulating film according to claim 1, wherein the treatment for eliminating the fluidity is a plasma treatment. 6. The insulating film according to claim 5, wherein at least the surface layer of the insulating film is cured and moisture in the insulating film is removed at the same time by performing the plasma treatment. Forming method. 7. The wettability of the surface of the insulating film after the plasma treatment is equal to or more than the wettability of the surface of the insulating film before the plasma treatment. The method for forming an insulating film as described above. 8. The insulating film is made of oxide, and at least one kind of gas made of molecules containing oxygen as a constituent atom is used as a reaction gas used in the plasma treatment. Method of forming insulating film. 9. The method for forming an insulating film according to claim 1, wherein the treatment for eliminating the fluidity comprises heating the substrate. 10. The method for forming an insulating film according to claim 1, wherein the treatment for eliminating the fluidity comprises holding the substrate in a vacuum. 11. The insulating film is formed in the container for forming the insulating film, and then the process of eliminating the fluidity is continuously performed in the container.
The method for forming an insulating film according to the above. 12. After forming the insulating film in the container for forming the insulating film, the substrate is transported into the container for removing the fluidity, and the inside of the container for removing the fluidity is transferred. 2. The method for forming an insulating film according to claim 1, wherein the treatment for eliminating the fluidity is performed. 13. The method for forming an insulating film according to claim 1, wherein the step is caused by a wiring, and the insulating film is an interlayer insulating film formed on the wiring.