JP2002110645A - Method for cleaning semiconductor device manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove Co remaining in a reaction chamber without opening to the atmosphere, to share production of CoSi ₂ used and non-used types, and to improve production efficiency. SOLUTION: A gas plasma 19b is applied by applying high frequency power to a gas introduced into a reaction chamber 17 evacuated to a vacuum.
Generate Thereafter, the generated gas plasma 19
b and the Co atoms 18 adhered to the inner wall of the reaction chamber 17 react with each other, whereby C adhering to the inner wall of the reaction chamber 17 is formed.
o The atoms 18 are removed from the reaction chamber 17. here,
The gas plasma 19b is generated by applying high frequency power to a mixed gas of a CO gas introduced into the reaction chamber 17 and a gas containing at least one H in a molecular formula.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a semiconductor device manufacturing apparatus, and more particularly to a method for removing heavy metals adhering to an inner wall of a reaction chamber when processing a semiconductor device in a vacuum.

[0002]

2. Description of the Related Art Along with miniaturization and speeding-up of an LSI, silicide, which is a compound of a refractory metal and Si, is used as a gate wiring material and a diffusion layer in order to reduce the resistance of a gate wiring and a diffusion layer. Has become commonplace. In recent years, in LSI, as a metal for silicide, C
o has begun to be adopted.

FIGS. 6 to 8 are views showing a manufacturing process of a semiconductor device according to the prior art. 6 shows a cross-sectional view of the wafer after the opening of the contact hole, FIG. 7 shows a state of the reaction chamber after the etching processing, and FIG. 8 shows a dry etching processing with Co remaining on the inner wall of the reaction chamber. In this case, the reaction between the gas plasma and Co in the reaction chamber is shown.
Hereinafter, a method of manufacturing a semiconductor device according to the related art will be described.

[0006] First, as shown in FIG. 6, a CoSi ₂ layer 12 is formed near the surface of a Si substrate 11. These Si
On the substrate 11 and the CoSi ₂ layer 12, a SiN film 13 as a barrier film of the CoSi ₂ layer 12 and an oxide film 14 as an insulating film
Is formed. Here, the thickness of the SiN film 13 is, for example, 450 °, and the thickness of the oxide film 14 is, for example, 4500 °.
It is. Next, a resist film 15 is spin-coated on the oxide film 14, and the resist film 15 is patterned into a desired electric circuit pattern using lithography and etching.

Next, using the resist film 15 patterned by dry etching as a mask,
Oxide film 14 is etched until the surface of film 13 is exposed. The etching conditions at this time are, for example, a pressure of 40
mT, RF power is 1700 W, gas is C ₄ F ₈ / CO /
Ar = 16/300/380 sccm. Next, the exposed SiN film 13 is removed by etching. The etching condition at this time is, for example, a pressure of 50 m.
T, RF power is 150 W, gas is CF ₄ / Ar = 10 /
180 sccm. Thus, the contact hole 16 is formed on the CoSi ₂ layer 12.

Here, as shown in FIG. 6, after forming the contact hole 16, the CoSi ₂ layer 12 is etched by about 50 °. This is because, in order to open all the contact holes 16 on the Si substrate 11 equally, the SiN
This is for performing an excessive etching of a certain amount or more with respect to the film thickness of the film 13. This excessive etching is generally called over-etching. For example, a time equivalent to 10% of the film thickness (here, 45 ° in terms of the thickness of the SiN film 13) is set to S.
The etching is performed by adding the etching time for the thickness of the iN film 13. This over-etching cannot be omitted in order to reliably open the contact hole 16 on the Si substrate 11 and to secure electrical contact between the contact and the CoSi ₂ layer 12.

As shown in FIG. 7, the etching of the Si wafer 10a is performed on the lower electrode 21 in the reaction chamber 17 of the dry etching apparatus, as shown in FIG.
Is carried out. The lower electrode 21 is connected to a high-frequency power supply 22 for applying high-frequency power, and a blocking capacitor 23 is arranged between the high-frequency power supply 22 and the lower electrode 21.

Incidentally, the Si of the CoSi ₂ layer 12 etched at the time of over-etching is expressed by the following equation (1).
Is converted to fluoride and exhausted.

Si + 4F → SiF ₄ ↑ (1) However, it is difficult to exhaust Co since a complex is formed by F. Therefore, after the contact hole 16 is formed on the CoSi ₂ layer 12, as shown in FIG. 7, Co 18 remains on the inner wall of the reaction chamber 17 in the dry etching apparatus or on the Si wafer 10a. In addition, the broken line part in FIG. 7 has shown the adhesion area | region of Co18.

Next, as shown in FIG. 8, the Si wafer 10a in which the contact hole 16 is formed is carried out of the reaction chamber 17, and another new Si wafer 10b is carried in on the lower electrode 21 of the reaction chamber 17. You. Then, while the Co 18 is left on the inner wall of the reaction chamber 17, the dry etching of the Si wafer 10b is performed.

At this time, since the inner wall of the reaction chamber 17 is sputtered by ions in the plasma 19, Co1
8 is beaten from the inner wall. The conditions for generating the plasma 19 at this time are, for example, a pressure of 50 mT and an RF power of 150
W and gas are CF ₄ / Ar = 10/180 sccm.

However, the beaten-out Co 18 is ionized in the plasma 19, and comes back onto the Si wafer 10b with a certain probability to contaminate the semiconductor device. When Co18 is CoSi ₂ , the silicide itself is stable, so that there is no problem in device operation.
CoSi ₂ cannot be formed in such an amount as to fly over the wafer 10b, but only diffuses into the Si wafer 10b. In such a case, a problem occurs in device operation such as inducing a crystal defect in the wafer or forming a level in the gate oxide film.

FIG. 9 shows a result of analyzing the surface of the Si wafer 10b placed on the lower electrode 21 of the reaction chamber 17 by generating gas plasma while leaving Co18 on the inner wall of the reaction chamber 17. The plasma generation conditions at this time are, for example, a pressure of 50 mT, an RF power of 150 W, and a gas of CF.
₄ / Ar = 10/180 sccm.

As shown in FIG. 9, Co is 1E12ato.
It can be seen that ms / cm ² or more is detected. This C
The amount of contamination by o may cause a crystal defect in a device not using CoSi _2, which causes a problem in device operation. Therefore, a device using CoSi ₂ and a device using CoSi ₂
Devices that do not use Si ₂ cannot share an etching apparatus, causing a problem that the operation of the manufacturing process is difficult.

[0015]

As described above, the CoS
When the Co to LSI without using a i ₂ has an adhesion above a certain level concentrations wafer or to induce crystal defects, etc. or to form a level in the gate oxide film, defects in the operation of the LSI Has the potential to become Therefore, at the time of manufacture, the product is not used the product and CoSi ₂ using CoSi ₂ it is necessary to separate the production line, a problem that efficient production can not be performed occurs.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to remove Co remaining in a reaction chamber without opening to the atmosphere, and to remove CoSi _2.
It is an object of the present invention to provide a method of cleaning a semiconductor device manufacturing apparatus capable of sharing production of a used product type and a non-used product type and improving production efficiency.

[0017]

The present invention uses the following means to achieve the above object.

According to the method of cleaning a semiconductor device manufacturing apparatus of the present invention, a gas plasma is generated by applying high-frequency power to a gas introduced into a vacuum-evacuated reaction chamber; Removing the Co atoms attached to the inner wall of the reaction chamber from the reaction chamber by reacting the atoms with the Co atoms attached to the inner wall of the reaction chamber.

[0019] The gas plasma may be generated by applying high-frequency power to a CO gas introduced into the reaction chamber.

Further, the gas plasma may be generated by applying high frequency power to a mixed gas of a CO gas introduced into the reaction chamber and a gas containing at least one H in a molecular formula. Here, the gas containing at least one H in the molecular formula is, for example, CHF ₃ , CH ₂ F ₂ , N
It is a gas composed of either H ₃ or CH ₃ OH.

According to the method for cleaning a semiconductor device manufacturing apparatus of the present invention, it is possible to effectively remove Co atoms remaining in the reaction chamber without opening to the atmosphere by performing the plasma treatment. Therefore, since the production of the used product type and the non-used product type of CoSi ₂ can be shared, the production efficiency can be improved.

[0022]

Cleaning method of an apparatus for manufacturing a semiconductor device of the embodiment of the present invention is a manufacturing process of a semiconductor device using the CoSi _2, when the contact hole to the CoSi ₂ layer on by dry etching, This makes it possible to remove Co remaining in the reaction chamber without opening the reaction chamber to the atmosphere. Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 are views showing a cleaning step of the semiconductor device manufacturing apparatus according to the embodiment of the present invention. FIG. 1 shows a cross-sectional view of the wafer before opening the contact hole.
FIG. 2 shows a cross-sectional view of the wafer after opening the contact holes, FIG. 3 shows the state of the reaction chamber after the etching processing, and FIG. 4 shows a dry etching processing with Co remaining on the inner wall of the reaction chamber. Gas plasma and C in the reaction chamber
The reaction with o is shown. Hereinafter, a method for cleaning a semiconductor device manufacturing apparatus according to an embodiment of the present invention will be described.

First, as shown in FIG. 1, a CoSi ₂ layer 12 is formed near the surface of a Si substrate 11. These Si
On the substrate 11 and the CoSi ₂ layer 12, an SiN film 13 as a barrier film of the CoSi ₂ layer 12 and an oxide film 14 as an insulating film
Is formed into a film. Here, the thickness of the SiN film 13 is, for example, 450 °, and the thickness of the oxide film 14 is, for example, 4500 °.
It is. Next, a resist film 15 is spin-coated on the oxide film 14, and the resist film 15 is patterned into a desired electric circuit pattern using lithography and etching.

Next, as shown in FIG. 2, the oxide film 14 is etched by dry etching using the patterned resist film 15 as a mask until the surface of the SiN film 13 is exposed. The etching conditions at this time are as follows:
For example, the pressure is 40 mT, the RF power is 1700 W, and the gas is C ₄ F ₈ / CO / Ar = 16/300/380 scc.
m. Next, the exposed SiN film 13 is removed by etching in a reaction chamber 17 different from the reaction chamber in which the oxide film 14 has been etched. The etching conditions at this time are, for example, a pressure of 50 mT, an RF power of 150 W,
The gas is CF ₄ / Ar = 10/180 sccm. Thus, the contact hole 16 is formed on the CoSi ₂ layer 12. At this time, the CoSi ₂ layer 12 has a thickness of 50 °.
Etched to a degree.

The above-mentioned SiN film 13 on the Si wafer 10a
As shown in FIG. 3, the etching process is performed on the lower electrode 21 in the reaction chamber 17 of the dry etching apparatus.
This is performed with the i-wafer 10a placed thereon. The lower electrode 21 is connected to a high-frequency power supply 22 for applying high-frequency power, and a blocking capacitor 23 is arranged between the high-frequency power supply 22 and the lower electrode 21.

Further, after performing the opening of the contact hole 16 on the CoSi ₂ layer 12, since the CoSi ₂ layer 12 is etched away, as shown in FIG. 3, the reaction chamber 17 in a dry etching apparatus An etching product composed of Co18 remains on the inner wall and the Si wafer 10a. In addition, the broken line part in FIG. 3 has shown the adhesion area | region of Co18.

Thereafter, the Si wafer 10a in which the contact holes 16 are formed is carried out of the reaction chamber 17, and another new Si wafer 10b is carried in the reaction chamber 17. Here, a product wafer on which a semiconductor device is formed is not used as another Si wafer 10b, but a wafer on which no patterning is performed and a semiconductor device is not formed is used.

Next, as shown in FIG.
With Co18 remaining on the inner wall of the reaction chamber 17, Si
Dry etching of the wafer 10b is performed. On this occasion,
CO and CHF₃And O₂High frequency power supply to mixed gas with
By applying high-frequency power, gas is introduced into the reaction chamber 17.
Plasma 19b is generated. Plasma 19b at this time
For example, the pressure is 40 mT and the RF power is 3
00W, gas is CHF ₃/ CO / O₂= 45/300 /
5 sccm for 600 seconds. Also, the Si wafer 10b
Some are C, CF⁺, CF2⁺, CF3⁺, CF4⁺, C
⁺, F⁺, Ar ⁺There is an etching species consisting of
You.

By the way, Co reacts with CO,
It is known that a reaction represented by the following formula (2) produces a carbonyl compound.

2Co + 8CO → [Co ₂ (CO) ₈ ] (2) Further, the carbonyl compound produced by the formula (2) reacts with H 2 to cause a reaction represented by the following formula (3).

H2 + [Co ₂ (CO) ₈ ] → 2H [Co (CO) ₄ ] ↑ (3) Here, the boiling point of H [Co (CO) ₄ ] shown in the formula (3) is 10 ° C. Since the vapor pressure has a very high property, the possibility that H [Co (CO) ₄ ] remains in the reaction chamber 17 is very low.

Accordingly, the gas plasma 19b composed of CO, CHF ₃ and O ₂ is exposed to the gas plasma 19b adhering to the inner wall of the reaction chamber 17.
Exposure to 18 causes the reactions shown in equations (2) and (3). As a result, Co adhered to the inner wall of the reaction chamber 17
18 is transformed into H [Co (CO) ₄ ]. Thereby, it becomes possible to efficiently discharge Co18 adhered to the inner wall of the reaction chamber 17 to the outside of the reaction chamber 17.

At this time, C is formed by sputtering.
o18 is detached from the inner wall of the reaction chamber 17 to remove the Si wafer 10
In some cases, however, Co18 attached to the Si wafer 10b does not damage the device operation because the Si wafer 10b on which no semiconductor device is formed is used for such plasma processing.

FIG. 5 shows Co18 remaining on the inner wall of the reaction chamber 17.
CO and CHF₃And O ₂And high to mixed gas
A frequency plasma is applied to generate gas plasma,
Si wafer 10b placed on lower electrode 22 of reaction chamber 17
2 shows the results of analyzing the surface.

As shown in FIG. 5, the amount of Co detected by the analysis is about 1E9 atoms / cm ² , and it can be seen that the amount of contamination is reduced by about three orders of magnitude as compared with the conventional case.
With such an amount of contamination, there is almost no possibility of inducing a crystal defect in a device not using CoSi ₂ . Therefore,
A device using CoSi ₂ by performing plasma processing using a mixed gas of CO, CHF ₃ and O ₂ ,
i ₂ In a device that does not use, it is possible to share the etching apparatus, it becomes possible to streamline the management of manufacturing processes.

According to the embodiment of the present invention, by performing the plasma treatment with the mixed gas of CO, CHF ₃ and O ₂ , the Co atoms remaining in the reaction chamber 17 can be effectively released without opening to the atmosphere. Can be removed. Therefore, since the production of the used product type and the non-used product type of CoSi ₂ can be shared, the production efficiency can be improved.

In the above embodiment of the present invention,
The gas of the gas plasma 19b for carbonylating Co18 is not limited to a mixed gas of CO, CHF ₃ and O ₂ . The atom required for carbonylation is CO, and this carbonyl compound is reacted with H to form 2H having a high vapor pressure.
[Co (CO) ₄ ] can be generated. Therefore, it is important to expose Co using a gas plasma of a mixed gas of CO and a gas containing at least one H in a molecular formula. The gas containing at least one H in the molecular formula includes, for example, gas such as CH ₂ F ₂ , NH ₃ , and CH ₃ OH in addition to CHF ₃ described in the above embodiment. Even when these gases are used, it is possible to obtain the same effects as those in the above-described embodiment of the present invention.

In the above-described embodiment of the present invention, the cleaning of Co18 is performed after the processing of one Si wafer 10a.
After the processing of (wafer) wafers is performed, the cleaning processing of Co18 may be performed collectively.

In the above embodiment of the present invention, Si
The etching of the N film 13 and the oxide film 14 is performed in separate reaction chambers, and the cleaning of the reaction chamber 17 in which the SiN film 13 has been etched is taken as an example. Alternatively, the present invention may be applied to cleaning of a reaction chamber where the oxide film 14 has been etched.

In the above embodiment of the present invention, a dry etching apparatus has been described. However, the cleaning method of the present invention can be applied to a cleaning process of a film forming chamber of a sputtering apparatus for forming a Co film. . For example, a plasma made of a mixed gas of the above-mentioned CO and a gas containing at least one H in a molecular formula is generated in the film formation chamber, and the inner wall of the reaction chamber and parts in the reaction chamber are exposed to the plasma. This allows
Co deposited in the reaction chamber can be effectively removed, and effects such as a reduction in the number of cleaning times of parts can be obtained.

In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0043]

As described above, according to the present invention, Co remaining in the reaction chamber is removed without opening to the atmosphere,
It is possible to provide a method of cleaning a semiconductor device manufacturing apparatus capable of improving production efficiency by sharing production between a used product type and a non-used product type of CoSi ₂ .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a wafer before opening a contact hole according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the wafer after opening a contact hole according to the embodiment of the present invention;

FIG. 3 is a diagram showing a state of a reaction chamber after an etching process according to the embodiment of the present invention.

FIG. 4 is a diagram showing a reaction between gas plasma and Co in the reaction chamber when dry etching is performed with Co remaining on the inner wall of the reaction chamber according to the embodiment of the present invention.

FIG. 5 is a diagram showing an amount of Co adhering on a wafer according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a wafer after opening a contact hole according to a conventional technique.

FIG. 7 is a diagram showing a state of a reaction chamber after an etching process according to a conventional technique.

FIG. 8 is a diagram showing a reaction between gas plasma and Co in a reaction chamber when dry etching is performed in a state where Co is left on the inner wall of the reaction chamber according to the conventional technique.

FIG. 9 is a diagram showing the amount of Co deposited on a wafer according to a conventional technique.

[Explanation of symbols]

10a, 10b: Si wafer, 11: Si substrate, 12: CoSi ₂ layer, 13: SiN film, 14: oxide film, 15: resist film, 16: contact hole, 17: reaction chamber, 18: inside wall of reaction chamber Co adhered, 19, 19a, 19b: gas plasma, 21: lower electrode, 22: high frequency power supply, 23: blocking capacitor.

Claims (4)

[Claims] A step of applying a high-frequency power to a gas introduced into a vacuum-evacuated reaction chamber to generate gas plasma; and a step of generating the gas plasma and Co atoms adhering to an inner wall of the reaction chamber. Removing the Co atoms attached to the inner wall of the reaction chamber from the reaction chamber from the reaction chamber. 2. The method for cleaning a semiconductor device manufacturing apparatus according to claim 1, wherein said gas plasma is generated by applying high-frequency power to a CO gas introduced into said reaction chamber. 3. The gas plasma according to claim 1, wherein the gas plasma is generated by applying high-frequency power to a mixed gas of a CO gas introduced into the reaction chamber and a gas containing at least one H in a molecular formula. Item 2. A method for cleaning a semiconductor device manufacturing apparatus according to Item 1. 4. The gas containing at least one H in the molecular formula includes CHF ₃ , CH ₂ F ₂ , NH ₃ , and CH ₃ OH.
2. The method for cleaning a semiconductor device manufacturing apparatus according to claim 1, wherein the gas is any one of the following.