JPH08306683A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To make it possible to form a silicon oxide insulating film, which is superior in self-reflow properties and is high in gap filling characteristics, by a method wherein the silicon oxide insulating film is formed on a substrate to be treated by a normal pressure CVD method, which is performed using raw gas containing organic silane gas, oxidizing gas and water vapor as its main components. CONSTITUTION: A substrate 11 to be treated and to be formed with a silicon oxide insulating film is set on a substrate stage 12 provided with a built-in heater 13. Raw gas, which is introduced in a gas introducing hole 16, is diffused by a gas diffusion plate 15 and is uniformly jetted on the surface of the substrate 11 through a gas shower head 14 having porous plate-shaped gas blow-off holes to the substrate 11. Here, as the raw gas, raw gas containing organic silane gas, oxidizing gas and water vapor its main components is used and the silicon oxide insulating film is formed on the substrate 11 to be treated by a normal pressure CVD method using the raw gas. As the oxidizing gas, gas containing ozone or containing ozone as its main component is desirable and it is also desirable to apply ultrasonic waves to the substrate to be treated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more specifically, it is capable of forming a flat surface on a substrate to be processed having a step or a recess and obtaining a silicon oxide excellent in film quality. The present invention relates to a method for manufacturing a semiconductor device including a step of forming a system insulating film.

[0002]

2. Description of the Related Art With the progress of higher integration of semiconductor devices such as LSI and the miniaturization of the design rule from sub-half micron to quarter micron, the pattern width of internal wiring is being reduced. On the other hand, in order to keep the wiring resistance at a low level and prevent signal propagation delay and various migrations, it is necessary to secure the wiring cross-sectional area. That is, since the height of the wiring is required to some extent, the aspect ratio of the wiring and the aspect ratio of the gap (recess) between the adjacent wirings tend to increase.

When such fine wiring is used as a multilayer wiring, a flattened interlayer insulating film is formed on a step or a gap formed by the lower wiring to secure a flat surface,
It is necessary to repeat the process of forming the upper layer wiring on this. Therefore, a method of forming an interlayer insulating film excellent in flatness and film quality is one of the key processes for highly integrated semiconductor devices.
It has become one.

Conventionally, various methods for forming a planarized interlayer insulating film have been developed. For example, a monthly review of these forming methods can be found in page 81 of the November 1989 issue of Semiconductor World magazine (published by Press Journal). ing. Of these, TEOS (Tetraethyl or
thosilicate, or Tetraeth
organic silane gas such as oxysilane) and O ₂
Alternatively, a silicon oxide-based insulating film formed by a CVD method using an oxidizing gas such as O ₃ as a raw material gas is a so-called self-flow process that can absorb a step difference in a base during film formation to obtain a good step coverage. Attention has been paid.

CV using an organic silane-based gas and an oxidizing gas
D is roughly classified into plasma CVD and atmospheric pressure CVD depending on the difference in reaction design. Of these, plasma CVD is 2
Since the reaction temperature can be lowered to about 50 ° C., it can be used as an interlayer insulating film on Al-based metal wiring which is a low melting point metal. Especially, H ₂ O (steam) as oxidizing gas
It is said that, by using the above method, an interlayer insulating film on a high aspect ratio Al-based metal wiring can be formed without generating voids. It is considered that this is because the addition of H ₂ O enhances the affinity between the surface of the base material layer and the intermediate product and promotes the self-flow of the interlayer insulating film. Regarding this type of plasma CVD, the proceedings of the 38th Joint Lecture on Applied Physics (1991 Spring Annual Meeting) p632, Lecture Nos. 29p-V-8 and 29p-V-9, or JP-A-5-121568. It has been proposed in the publication.

On the other hand, the atmospheric pressure CVD has a reaction temperature slightly higher than that of the plasma CVD, but has a large deposition rate. In particular, the atmospheric pressure CVD using an organic silane-based gas and an inorganic acid as a source gas has an improved hydrolysis rate. JP-A-3-116835 discloses that an interlayer insulating film having a low hydroxyl content is formed.

[0007]

However, H ₂ O has a weak oxidizing action, and a large amount of hydroxyl groups and organic components remain in the formed interlayer insulating film. For this reason, gas desorption from the interlayer insulating film, shrinkage or cracking of the film due to this,
There are still problems such as a decrease in withstand voltage and the occurrence of after-corrosion when an Al-based metal wiring is used.

Further, in atmospheric pressure CVD using an inorganic acid, the hydrolysis rate is very high, and its control is difficult. Therefore, the hydrolysis products of low molecular weight are preferentially deposited on the substrate to be processed, which is important. In some cases, it was difficult to obtain the self-flow shape.

Therefore, the applicant of the present application filed Japanese Patent Application No.
No. 022197 proposes a method of increasing the reaction rate of dehydration condensation by adding a basic gas as a reaction catalyst to a raw material gas. By this process, it became possible to reduce the hydroxyl groups in the film and obtain a reaction product having a large self-flow shape with a relatively large molecular weight to improve the step coverage.

However, this method using a basic catalyst has a very good self-flow shape on a substrate to be processed having the same material surface, but has different material surfaces such as metal and insulating material. In the substrate to be processed, the growth rate and the self-flow shape were sometimes affected.

An object of the present invention is to further improve the above-mentioned conventional technique and to form a silicon oxide type insulating film by atmospheric pressure CVD using an organic silane type gas, which is excellent in self-flow property and has a high gap fill characteristic. A method of manufacturing a semiconductor device including a step of forming a system insulating film.

Another object of the present invention is to reduce the number of hydroxyl groups and organic substances in the film, to prevent gas desorption after film formation and to prevent shrinkage and cracks of the film, which is highly reliable, and to be highly reliable. It is an object of the present invention to provide a method for manufacturing a semiconductor device including a step of forming an insulating film.

[0013]

A method of manufacturing a semiconductor device according to the present invention is proposed to solve the above-mentioned problems, and an organic silane-based gas, an oxidizing gas and H ₂ O (steam) are used. A method of manufacturing a semiconductor device, comprising a step of forming a silicon oxide insulating film on a substrate to be processed by an atmospheric pressure CVD method using a source gas as a main component.

The oxidizing gas is preferably ozone or a gas mainly containing ozone. Applying ultrasonic waves to the substrate to be processed is also one of desirable modes.

Further, the method for manufacturing a semiconductor device of the present invention is an atmospheric pressure CVD method using a source gas mainly containing an organic silane-based gas, an oxidizing gas, H ₂ O (steam) and a basic gas.
And a step of forming a silicon oxide type insulating film on the substrate to be processed by a method.

Also in this case, it is desirable that the oxidizing gas is ozone or a gas containing ozone as a main component. As the basic gas, NH ₃ , N ₂ H ₂ , N ₂ H ₂
It is preferably either a derivative or an alkylamine. Applying ultrasonic waves to the substrate to be processed is also one of desirable modes. The ultrasonic waves may be applied to the substrate stage to excite the substrate to be processed, but alternatively, the source gas nozzle or the source gas in the CVD chamber may be excited.

Examples of the organic silane-based gas used in the present invention include TEOS and Tetramethyl.
orthosilicate (TMOS), Diace
toxy digitally butoxy sil
ane (DADBS), Tetraethyl sil
one (TES), Tetramethyl sila
ne (TMS), Octamethyl cyclo-
tetrasiloxane (OMCTS), Tetr
apropoxy silane (TPOS), Tet
ramethyl cyclo-tetrasilox
Other organic silane-based gas such as ane (TMCTS) can be appropriately used. An organic silane-based gas having fluorine as a substituent may be adopted. Inorganic silane gases such as SiH ₄ and Si ₂ H ₆ may be added to these organic silane gases.

The atmospheric pressure CVD in the present invention is not limited to 1 atm (1.01 × 10 ⁵ Pa) and may be a slightly reduced pressure atmosphere or a pressurized atmosphere.

[0019]

The essence of the present invention is that, in atmospheric pressure CVD using an organic silane-based gas, H ₂ O is added to the raw material gas to react with the base material layer without depending on the surface property of the base material layer. It is to improve the affinity (wettability) with the intermediate product and enhance the self-flow property and the gap fill property.
Further, a gas mainly containing ozone is added as an oxidizing gas to thoroughly carry out the oxidation reaction to reduce the residual organic substances and hydroxyl groups in the silicon oxide-based material layer and improve the film quality. By selecting the composition of the raw material gas, it is possible to form a silicon oxide-based material layer that satisfies the high deposition rate of atmospheric pressure CVD, the gap fill property, and the film quality.

Furthermore, if a basic gas is added to the above-mentioned raw material gas, the reaction rate of dehydration condensation is accelerated, the hydroxyl groups in the film are reduced, and the film quality can be further improved.

Further, by applying ultrasonic vibration to the substrate to be processed, the vibration energy of the substrate to be processed and the vibration energy level such as translation or rotation of the source gas molecules are increased and the hydrolysis reaction is activated. Therefore, it is possible to form a film with good step coverage and with good efficiency even at a lower temperature than in the past.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. First, a configuration example of a single-wafer CVD apparatus used in each embodiment of the present invention will be described with reference to the schematic sectional view shown in FIG.

The substrate 11 to be processed on which the silicon oxide type insulating film is to be formed is set on the substrate stage 12 having the heater 13 built therein. The raw material gas introduced into the gas introduction hole 16 is diffused by the gas diffusion plate 15, passes through the gas shower head 14 having a perforated plate-like gas blowing hole facing the substrate 11 to be processed, and then is directed to the surface of the substrate 11 to be processed. Ejects uniformly. Reference numeral 17 is a gas ring arranged on the upper surface of the outer periphery of the substrate to be processed, which is a hollow annular member having a large number of gas ejection holes, to which a part of the raw material gas, a diluent gas or the like is added if necessary And reference numeral 18 is a gas discharge hole.

A characteristic part of the CVD apparatus of the present invention is an ultrasonic vibration applying means which is incorporated in the substrate stage 12 and excites the substrate 11 to be processed.
It is possible to excite 1. As the ultrasonic vibration applying means, various electric / acoustic transducers such as a piezoelectric element, a magnetostrictive element, an electrodynamic type using a magnetic circuit and a coil may be arbitrarily used.

Example 1 Next, a specific example of the silicon oxide insulating film forming step will be described. In this embodiment, TEOS and H ₂ are used as raw material gases.
This is an example of forming a planarization film on an Al-based metal wiring by atmospheric pressure CVD using O and O ₃ , which is shown in FIG.
This will be described with reference to (b).

First, the wiring layer 3 made of, for example, an Al-based metal is formed on the interlayer insulating film 2 on the semiconductor substrate 1 made of Si or the like, and this is used as a substrate to be processed. Since the substrate to be processed shown in FIG. 1A has a plurality of stepped uneven portions having different widths on its surface, it is necessary to form a planarization interlayer insulating film when forming an upper layer wiring in the next step. . Although FIG. 1A shows only a narrow stepped recess having a width of 0.5 μm or less, a wide stepped recess having a width of 1 μm or more, which is not shown, is also formed on the substrate to be processed.

The substrate stage 1 of the CVD apparatus shown in FIG.
The substrate 11 to be processed is placed on the substrate 2 and atmospheric pressure CVD of a silicon oxide insulating film is performed under the following conditions. TEOS 150 sccm H ₂ O 50 sccm O ₃ 100 sccm Gas pressure Normal pressure Substrate temperature 300 ° C. Since H ₂ O has a boiling point of 100 ° C., a heated H ₂ O bubbler is used with a carrier gas such as He as in TEOS. Bubbling and supply to the CVD chamber. The H ₂ O container may be heated to near the boiling point to be vaporized and introduced without a carrier gas. Other vaporization methods such as burning method and ultrasonic atomization method are adopted. In any case, it is desirable to heat the introduction pipe system to prevent dew condensation of H ₂ O.

The above-mentioned atmospheric pressure CVD process is characterized in that, as basic characteristics of the raw material gas composition, the polymer as an intermediate product has an appropriate molecular weight and the effect of removing hydroxyl groups and organic substances is high. For this reason, the uniformly planarized silicon oxide insulating film 4 having no surface dependence of the substrate 11 to be processed was formed at a relatively low temperature. This state is shown in FIG.

According to the present embodiment, the atmospheric pressure CVD using TEOS, H ₂ O and O ₃ is performed to obtain 0.5 on the substrate to be processed.
Not only fine stepped recesses having a size of μm or less but also wide stepped recesses were uniformly buried and the silicon oxide insulating film 4 with good film quality was formed.

Example 2 In this example, AOS was performed by atmospheric pressure CVD using TEOS, H ₂ O and O ₃ as source gases and NH ₃ as a basic gas.
This is an example in which a flattening film is formed on the 1-system metal wiring, which will be described with reference to FIGS. 1 (a) and 1 (b).

Since the substrate to be processed shown in FIG. 1 (a) is the same as that of the previous embodiment, duplicate description will be omitted. The substrate 11 to be processed is placed on the substrate stage 12 of the CVD apparatus shown in FIG. 2, and the atmospheric pressure CVD of the silicon oxide insulating film is performed under the following conditions. TEOS 150 sccm H ₂ O 50 sccm O ₃ 100 sccm NH ₃ 10 sccm Gas pressure Normal pressure Substrate temperature 300 ° C.

In the above atmospheric pressure CVD step, NH ₃ is added as a basic catalyst to obtain the effect of Example 1, and in addition to promoting the reaction rate of dehydration condensation, the hydroxyl groups in the film are reduced, It is possible to further improve the film quality.

Example 3 This example is based on the previous Example 1, and ultrasonic waves were further applied to the substrate to be processed.
This will be described with reference to (a) and (b). The substrate to be processed shown in FIG. 1A used in this embodiment is the same as that in the first embodiment.

Substrate stage 1 of the CVD apparatus shown in FIG.
The substrate 11 to be processed is placed on the substrate 2 and atmospheric pressure CVD of the silicon oxide insulating film is performed under the following conditions. TEOS 150 sccm H ₂ O 50 sccm O ₃ 100 sccm Gas pressure Normal pressure Substrate temperature 270 ° C. Ultrasonic vibration 50 W (200 KHz)

According to the present embodiment, in addition to the effect of the first embodiment, the fluidity of the intermediate product on the substrate to be processed is enhanced, and the gap fill characteristic is further improved, although the substrate temperature is lowered. It is possible to form the flat silicon oxide based material layer 4.

Although the present invention has been described with reference to the three examples, the present invention is not limited to these examples.

Although TEOS is used as an example of the organic silane-based gas, other organic silane-based gas can be appropriately used as described above. By using an organic silane-based gas having F as a substituent, a SiOF-based silicon oxide-based material layer having a low dielectric constant characteristic can be formed. Inorganic silane gases such as SiH ₄ and Si ₂ H ₆ may be added to these organic silane gases.

PH ₃ , B ₂ H ₆ , AsH ₃ and Tri
methyl phosphate (TMP), Tti
By adding an impurity source gas such as methyl borate (TMB), PSG, BSG, BPSG, AsSG
It is also possible to form silicate glass such as.

Although O ₃ was used as the oxidizing gas, it is needless to say that other oxidizing gases such as O ₂ , NO ₂ and H ₂ O ₂ may be used or mixed.

NH ₃ was used as an example of the basic gas.
hydrazine (N ₂ H ₂ ) and its derivatives, CH ₃ N
It is also possible to use _{H 2, C 2 H 5 NH} 3, NH 2 (CH 2) 2 NH 2 and alkyl amines.

In addition, He, Ar, Xe are used as diluent gases.
It may be mixed and used noble gas or N ₂ and the like.

In each of the above-described embodiments, the case of forming the interlayer insulating film on the Al-based metal wiring has been exemplified, but the case of using another wiring material layer, the case of using as the final passivation film, and further the trench isolation. It is needless to say that the present invention can be applied to the case where the layer is embedded flat without generating voids.

[0043]

As is apparent from the above description, according to the present invention, the atmospheric pressure CVD mainly containing an organic silane-based gas, an oxidizing gas and H ₂ O enables stable and stable flatness and film quality. It is possible to form a silicon oxide-based material layer having a self-flow shape.

If a basic gas is further added to the raw material gas having the above composition, a silicon oxide type material layer having a further reduced content of hydroxyl groups can be formed.

Furthermore, by applying ultrasonic waves to the substrate to be processed during the atmospheric pressure CVD process, migration of intermediate products on the substrate to be processed can be promoted and a narrow gap can be filled flat without generating voids. It will be possible.

Since the quality of the silicon oxide-based insulating film is improved, the formed silicon oxide-based insulating film does not release moisture, shrinks, or cracks. Therefore, it can be used as an interlayer insulating film on an Al-based metal wiring. Even when used, there is no fear of occurrence of after-corrosion or migration.

With the above effects, it becomes possible to increase the reliability of the flattening interlayer insulating film or the like of the semiconductor device having a high step due to the heavy use of the multilayer wiring, and the effect of the present invention on the manufacturing process of the highly integrated semiconductor device. Is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view illustrating an atmospheric pressure CVD process according to Examples 1 to 3 of the present invention, in which (a) is a state in which a wiring layer having a step is formed on an interlayer insulating film, and (b) is flat. This is a state in which a converted silicon oxide insulating film is formed.

FIG. 2 is a schematic cross-sectional view showing a configuration example of a single wafer type atmospheric pressure CVD apparatus used in Examples 1 to 3 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Interlayer insulating film 3 Wiring layer 4 Silicon oxide type insulating film 11 Processed substrate 12 Substrate stage 13 Heater 14 Gas shower head 15 Gas diffusion plate 16 Gas introduction hole 17 Gas ring 18 Gas discharge hole 19 Ultrasonic vibration applying means

Claims (7)

[Claims] 1. An organic silane-based gas, an oxidizing gas and H
Atmospheric pressure C using raw material gas mainly composed of ₂ O (steam)
A method of manufacturing a semiconductor device, comprising a step of forming a silicon oxide insulating film on a substrate to be processed by a VD method. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the oxidizing gas contains ozone. 3. The method of manufacturing a semiconductor device according to claim 1, wherein ultrasonic waves are applied to the substrate to be processed. 4. An organic silane-based gas, an oxidizing gas, H ₂ O
A method of manufacturing a semiconductor device, comprising a step of forming a silicon oxide insulating film on a substrate to be processed by an atmospheric pressure CVD method using a source gas mainly composed of (steam) and a basic gas. . 5. The method of manufacturing a semiconductor device according to claim 4, wherein the oxidizing gas contains ozone. 6. The basic gas is NH ₃ , N ₂ H ₂ , N ₂
The method for manufacturing a semiconductor device according to claim 4, wherein the method is at least one selected from the group consisting of H ₂ derivatives and alkylamines. 7. The method of manufacturing a semiconductor device according to claim 4, wherein ultrasonic waves are applied to the substrate to be processed.