JPH07201985A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To avoid the fluctuation of an inter-wiring capacitance caused by the increase of a dielectric constant in a semiconductor device which has a plurality of insulating films having different dielectric constants are provided in layers between its upper and lower wiring layers. CONSTITUTION:A first insulating film 14 containing a number of Si-F bond groups and Si-OH bond groups is formed on an SiO2 insulating film 12 including a first metal wiring 13. Further, in a successive process, a second insulating film 15 containing Si-F bond groups less than the first insulating film 14 is formed on the first insulating film 14. Then the second insulating film 15 only is etched and levelled so as not to have the first insulating film 14 exposed from the surface. With this constitution, by protecting the first insulating film 14 from the atmosphere by the second insulating film 15, the increase of the dielectric constant of the first insulating film 14 caused by moisture absorption can be avoided.

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 having, for example, a multi-layer wiring structure, and more particularly, to manufacturing of a semiconductor device in which a plurality of insulating films having different dielectric constants are laminated between upper and lower wiring layers. Is used.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor device having a multilayer wiring structure, an insulating film having a low dielectric constant has been provided between upper and lower wiring layers for the purpose of reducing the capacitance between wirings. There is.

FIG. 4 shows an example of a conventional semiconductor device having a multilayer wiring structure. For example, in the conventional device, first, the SiO2 insulating film 2 is formed on the semiconductor substrate 1 by thermal oxidation, and then the first metal wiring 3 as the lower layer wiring is formed (FIG. 3A).

Next, the Si containing the first metal wiring 3 is formed.
An insulating film 4 is formed on the O2 insulating film 2 by a low pressure plasma method, and further, an insulating film 5 containing a large amount of Si--F bond groups and Si--OH bond groups is formed on the insulating film 4 ( The same figure (b)).

Then, the upper surface of the insulating film 5 is flattened by, for example, the resist etch-back RIE method or the CMP method (FIG. 7C). After that, an insulating film 6 for preventing moisture absorption of the insulating film 5 is formed on the flattened insulating film 5 by a low pressure plasma method, and further a second metal wiring or the like as an upper wiring is formed. Is performed ((d) in the same figure).

However, in the case of the above-mentioned conventional device,
The insulating film 5 containing a large amount of Si—F bond groups and Si—OH bond groups is planarized with the surface exposed.

Usually, the insulating film 5 contains a large amount of Si--F bond groups and Si--OH bond groups, so that the dielectric constant thereof can be suppressed low. Therefore, during or after the processing, the insulating film 5 is very likely to absorb moisture, and the Si--OH bond group and H in the film are absorbed.
This results in an increased content of -OH linking groups.

Since this causes the dielectric constant (ε) of the insulating film 5 to increase, there is a problem that characteristics are significantly deteriorated, such as an increase in inter-wiring capacitance and inter-wiring capacitance that control the operation speed. there were.

[0009]

As described above, in the past, since an insulating film containing a large amount of Si-F bond groups and Si-OH bond groups is very likely to absorb moisture, the film is exposed to the surface. If flattening is performed in the
The content of the —OH bond group and the H—OH bond group increases, and as a result, the inter-wiring capacitance and the inter-wiring capacitance increase with an increase in the dielectric constant, resulting in unstable characteristics due to variations in the dielectric constant. was there.

Therefore, an object of the present invention is to provide a method of manufacturing a semiconductor device capable of preventing an increase in inter-wiring capacitance and inter-wiring capacitance due to an increase in dielectric constant and stabilizing characteristics. .

[0011]

In order to achieve the above object, in the method of manufacturing a semiconductor device according to the present invention, a plurality of wiring layers having upper and lower wiring layers having different dielectric constants are formed. In the case of laminating insulating films, a step of forming a first insulating film having a low dielectric constant on the wiring on the lower layer side, and without exposing the upper surface of the first insulating film to the outside air,
A step of forming a second insulating film having a higher dielectric constant than the first insulating film on the upper part thereof, and planarizing the second insulating film without exposing the first insulating film to the surface. It consists of a process.

Further, in the method for manufacturing a semiconductor device of the present invention, in the case where a plurality of insulating films having different dielectric constants are laminated between upper and lower wiring layers having a multilayer structure, the lower layer side Forming a first insulating film containing a predetermined amount of Si-F bonding group and Si-OH bonding group on the wiring of, and without exposing the upper surface of the first insulating film to the outside air, Si-F is formed on top of the first insulating film
Forming a second insulating film having a low content of both or one of the bonding group and the Si—OH bonding group; and
And the step of flattening the insulating film without exposing the first insulating film on the surface.

[0013]

According to the present invention, since the first insulating film containing a large amount of Si-F bond groups and Si-OH bond groups can be prevented from absorbing moisture by the means described above, the dielectric constant of the insulating film between the wiring layers can be prevented. Can be kept stable.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a semiconductor device according to the present invention. That is, this semiconductor device has the SiO2 insulating film 12 formed on the Si substrate 11,
First metal wiring 1 formed on this SiO2 film 12
3. The SiO2 film 12 including the first metal wiring 13
First insulating film 14 formed on the first insulating film 1
A second insulating film 15 whose upper surface is flattened without exposing 4 to the surface, a second metal wiring 16 formed on the second insulating film 15, and a second metal wiring 16
And a passivation film 18 formed on the main surface of the device including the second metal wiring 16 and a connection hole (via hole) 17 for connecting the first metal wiring 13 to each other.

The SiO 2 insulating film 12 is formed to a thickness of about 0.6 μm by, for example, a thermal oxidation method. First above
The metal wiring 13 is formed, for example, by depositing an Al—Cu—Si alloy film with a thickness of about 0.6 μm by a sputtering method and processing the alloy film using a lithography technique and an anisotropic etching technique. To be done.

The first insulating film 14 contains a large amount of Si--F bond groups and Si--OH bond groups, and is composed of, for example, fluorocarbon compound gas (500 sec) and TE.
A film is formed with a thickness of about 0.8 μm in a low-pressure plasma at about 350 ° C. using OS gas.

The second insulating film 15 contains a smaller amount of Si--F bond groups than the first insulating film 14, and for example, the flow rate of the fluorocarbon-based compound gas can be maintained without breaking the reduced pressure state. (Or with
A film having a thickness of about 1.5 μm is formed with the film thickness set to zero.

In this case, the relationship between the dielectric constant (ε1) of the first insulating film 14 and the dielectric constant (ε2) of the second insulating film 15 is ε1 <ε2, for example ε1 = 3.4, ε2
= 4.1.

As the second insulating film 15, Si-
Not only the F bond group but also a smaller amount of Si—OH bond groups than the first insulating film 14 may be contained.

The second insulating film 15 is formed of, for example, Chemical Mechanical Polis.
Etching is performed by using the Hing (CMP) technique so that the surface is flattened.

In this case, the etching amount is such that the first insulating film 14 is not exposed on the surface, for example, the first insulating film 14 has a thickness of 0.1 μm or more and the second insulating film 14 has a thickness of 0.1 μm or more. Etching is performed so that the insulating film 15 of FIG.

This etching can be easily realized by controlling the load of the CMP apparatus and the motor rotation speed, for example. The second metal wiring 16 is, for example, Al—Cu.
It is formed by depositing a -Si alloy film with a thickness of about 0.6 μm by a sputtering method and processing the alloy film using a lithography technique and an anisotropic etching technique.

The connection hole 17 is provided with the second metal wiring 1
Prior to the formation of No. 6, in the openings formed in the first and second insulating films 14 and 15 corresponding to the connecting portions between the first metal wiring 13 and the second metal wiring 16. It is formed by selectively depositing W at about 200 ° C. by, for example, a low pressure CVD method.

The passivation film 18 is formed with a thickness of about 0.3 μm in a low pressure plasma at about 350 ° C. using, for example, TEOS gas. An opening 18a for connecting an external electrode is selectively formed in a part of the passivation film 18 by using, for example, a lithography technique and an NH4F solution.

According to this structure, the first insulating film 1
Since the second insulating film 15 can be planarized without exposing 4 to the surface, the post-treatment is, for example, a surface cleaning treatment with H2O or H2SO4 and H2O2.
Even if the surface cleaning treatment is performed using a mixed liquid of the above, moisture absorption into the film of the first insulating film 14 does not occur.

Therefore, the Si--O of the first insulating film 14 is
It is possible to solve the problem in the conventional device that the number of H-bonding groups and the number of H—OH bond groups increase, and the dielectric constant ε1 of the first insulating film 14 increases accordingly.

Next, with reference to FIG. 2, a method of manufacturing the apparatus of this embodiment shown in FIG. 1 will be described. First, as shown in FIG. 3A, the SiO2 insulating film 12 is formed on the Si substrate 11 by a thermal oxidation method to a thickness of about 0.6 .mu.m.

An Al--Cu--Si alloy film having a thickness of about 0.6 .mu.m is deposited on the SiO2 insulating film 12 by, for example, a sputtering method. The first metal wiring 13 is selectively formed by being processed by using an etching technique.

Then, as shown in FIG. 3B, a large amount of Si--F bond groups and Si--OH bond groups are contained on the SiO2 insulating film 12 including the first metal wiring 13. , The first insulating film 14 having a dielectric constant ε1 of 3.4 is formed of, for example, fluorocarbon compound gas (50
0 sec) and TEOS gas are used to form a film with a thickness of about 0.8 μm in a reduced pressure plasma at about 350 ° C.

After the first insulating film 14 is formed, the dielectric constant ε 2 is 4.1, which contains a smaller amount of Si-F bond groups than the first insulating film 14. The second insulating film 15 is formed to have a thickness of about 1.5 μm, for example, in a state where the flow rate of the fluorocarbon-based compound gas is reduced (or in a state where it is zero) without breaking the reduced pressure state. Be filmed.

Thereafter, as shown in FIG. 3C, the second insulating film 15 is etched by using, for example, the CMP technique, and is flattened leaving a thickness of 0.1 μm or more. Next, as shown in FIG. 3D, an opening for connecting the first metal wiring 13 and the second metal wiring 16 is formed, and for example, a reduced pressure CV is formed in the opening.
The connection hole 17 is formed by selectively depositing W at about 200 ° C. by the D method.

Further, on the second insulating film 15 corresponding to the connection hole 17, A is formed by, for example, a sputtering method.
After the 1-Cu-Si alloy film is deposited to a thickness of about 0.6 μm, the alloy film is processed by using the lithography technique and the anisotropic etching technique, whereby the second metal wiring 16 is formed. Are selectively formed.

Thereafter, on the second insulating film 15 including the second metal wiring 16, for example, TEOS gas is used, and the pressure is reduced to about 0.3 μm in a reduced pressure plasma at about 350 ° C.
The passivation film 18 is formed to a thickness of.

Then, an opening portion 18a for connecting an external electrode is selectively formed in a part of the passivation film 18 by using, for example, a lithographic technique and an NH4F solution, whereby the above-mentioned embodiment is carried out. The device is manufactured.

As mentioned above, the Si--F linking group and the S
The first insulating film containing a large amount of i-OH bond groups is prevented from absorbing moisture. That is, the first insulating film containing a large amount of Si—F bond groups and Si—OH bond groups is exposed to the outside air without being exposed to the outside air, and a smaller amount of Si—F bond than that can be continuously processed. A second containing group
The insulating film of is formed on the first insulating film,
Only the second insulating film is etched so that the first insulating film is not exposed on the surface. As a result, the second insulating film can protect the first insulating film from being exposed to the atmosphere or the liquid layer during and after the etching process, so that the dielectric constant of the first insulating film can be improved. It is possible to keep the rate stable. Therefore, it is possible to prevent the inter-wiring capacitance and inter-wiring inter-layer capacitance from increasing due to the moisture absorption of the film, thereby preventing the characteristics from becoming unstable due to variations in the dielectric constant. Is.

Moreover, by flattening the second insulating film by using the CMP technique, the manufacturing process can be simplified. In the above embodiment, the first
Although the case where the first insulating film is directly formed on the metal wiring has been described, the present invention is not limited to this, and as shown in FIG. 3, for example, between the first metal wiring 13 and the first insulating film 14, To S
An i02 insulating film (third insulating film) 21 may be formed.

This SiO 2 insulating film 21 is formed to have a thickness of about 0.05 μm in a low pressure plasma at about 350 ° C. by using, for example, TEOS gas after forming the first metal wiring 13.
Is formed with a thickness of.

After that, the semiconductor device having the structure shown in FIG. 3 can be manufactured by sequentially performing the above steps. In this case, the first metal wiring 13 is connected to the first insulating film 14
Since it can be separated from the first metal wiring 13,
For example, Ti or the like that easily reacts with the first insulating film 14 can be used.

After forming this SiO 2 insulating film 21,
It is also possible to continuously form the first insulating film 14 and the second insulating film 15 while maintaining the reduced pressure state. Of course, various modifications can be made without departing from the scope of the invention.

[0040]

As described above in detail, according to the present invention, it is possible to prevent the increase of the inter-wiring capacitance and the inter-wiring capacitance due to the increase of the dielectric constant, and to manufacture the semiconductor device capable of stabilizing the characteristics. A method can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional view schematically showing the manufacturing process of the semiconductor device.

FIG. 3 is a sectional view showing a schematic configuration of a semiconductor device according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a semiconductor device shown for explaining a conventional technique and its problems.

[Explanation of symbols]

11 ... Si substrate, 12 ... SiO2 insulating film, 13 ... First metal wiring, 14 ... First insulating film, 15 ... Second insulating film,
16 ... Second metal wiring, 17 ... Connection hole, 18 ... Passivation film, 21 ... SiO2 insulating film (third insulating film).

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device, comprising: laminating a plurality of insulating films having different dielectric constants between upper and lower wiring layers having a multi-layered structure; A step of forming a first insulating film, and a step of forming a second insulating film having a higher dielectric constant than the first insulating film above the first insulating film without exposing the upper surface of the first insulating film to the outside air. And a step of planarizing the second insulating film without exposing the first insulating film to the surface thereof. 2. A method of manufacturing a semiconductor device, comprising: laminating a plurality of insulating films having different dielectric constants between upper and lower wiring layers having a multilayer structure, wherein a predetermined amount of Si is provided on the lower wiring. A step of forming a first insulating film containing a —F bond group and a Si—OH bond group, and a step of forming the first insulating film on the upper surface of the first insulating film without exposing the upper surface to the outside air. Than Si-F bonding group and S
a step of forming a second insulating film having a low content of both or one of the i-OH bond groups, and a step of planarizing the second insulating film without exposing the first insulating film to the surface. A method of manufacturing a semiconductor device, comprising: 3. The step of planarizing the second insulating film comprises:
Chemical Mechanical Polish
The method of manufacturing a semiconductor device according to claim 2, wherein an ing (CMP) technique is used. 4. The manufacturing of a semiconductor device according to claim 2, wherein the step of forming the second insulating film is continuously performed in a depressurized state where the first insulating film is formed. Method. 5. A step of forming a third insulating film, which is different from the first and second insulating films, between the wiring on the lower layer side and the first insulating film. The method for manufacturing a semiconductor device according to claim 2.