JP2002167673A - Cvd film deposition method and method for removing deposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CVD film deposition method by which peeling of the surface of the walls in the chamber and/or in the surfaces of the members in the chamber is hard to occur, and to provide a method for removing depositions by which depositions causing film peeling in the surfaces of the walls in the chamber and/or in the surfaces of the members in the chamber can effectively be removed. SOLUTION: The inside of a chamber 11 for CVD film deposition treatment is subjected to cleaning with gaseouse ClF3. After that, the inside of the chamber is formed with plasma of a gas containing gaseous Ar and a reducing gas. By this plasma, depositions 50 consisting of AlF based substance deposited on the surfaces of the walls in the chamber and/or on the surfaces of the members in the chamber are removed. Successively, the inside of the chamber 11 is fed with a gas for precoat. Precoat films 51 are deposited on the surfaces where the depositions 50 are removed. After that, the inside of the chamber is charged with the body W to be treated. Then, film deposition treatment is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a CVD film forming method for performing a film forming process, and a method for removing a deposit attached to a chamber inner wall and / or a surface of a chamber inner member.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, Ti, Al, Cu or the like is used to fill holes between wirings formed in a semiconductor wafer (hereinafter simply referred to as a wafer) as a workpiece or as a barrier layer. Metals, WSi, Ti
A thin film is formed by depositing a metal compound such as N or TiSi.

Conventionally, thin films of these metals and metal compounds have been formed by physical vapor deposition (PVD). Recently, however, there has been a particularly demand for miniaturization and high integration of devices, and design rules have become particularly strict. Therefore, it is difficult to obtain sufficient characteristics with PVD having poor embedding properties. Therefore, such a thin film is formed by chemical vapor deposition (CVD), which can be expected to form a higher quality film.

For example, when forming a Ti thin film by CVD,
Is a film forming gas such as TiCl ₄Is used to reduce
As a gas, for example, H₂Is used. And like this
First, a pre-coating process is performed using
The main film forming process is performed. After such a film formation process,
Periodically or if necessary, for example, ClF₃Gas
Perform a leaning.

[0005]

However, in the formation of such a Ti thin film, a shower for gas supply arranged in a chamber, for example, is disposed in a chamber during pre-coating due to deposits at the time of cleaning. There is a problem that the film is peeled off from the surface of the head.

[0006] The present invention has been made in view of the above circumstances, and a CVD film forming method in which film peeling of a chamber inner wall and / or a member in a chamber is unlikely to occur, and a method of film peeling of a chamber inner wall and / or a member in a chamber. An object of the present invention is to provide a method for removing extraneous matter that can effectively remove extraneous matter that causes the extraneous matter.

[0007]

The inventors of the present invention have investigated the film peeling during such precoating and found that C
At the time of cleaning with IF ₃ gas, F generated by decomposition of ClF ₃ gas and Al constituting the chamber material react with each other to form an AlF-based material, and this AlF-based material is, for example, a gas disposed in the chamber. It has been found that since the AlF-based deposit is deposited on the surface of the supply shower head and remains as an easily peelable deposit, the precoat film when the precoating is performed is peeled off together with the AlF-based deposit when the AlF-based deposit becomes thick. . Therefore, by removing such deposits during cleaning, it is possible to prevent such film peeling during precoating.

[0008] The present invention has been made based on such knowledge, and A is provided in a chamber for performing a CVD film forming process.
forming a plasma of a gas containing an r gas and a reducing gas, and removing deposits attached to the inner wall of the chamber and / or the surface of the member in the chamber by the plasma;
Continuously supplying a pre-coating gas into the chamber to form a pre-coat film on the surface from which the deposits have been removed; loading a workpiece into the chamber; and forming a film in the chamber. Supplying a gas and performing a film forming process on the object to be processed.

Further, according to the present invention, after cleaning the inside of a chamber for performing a CVD film forming process with a ClF ₃ gas, a plasma of a gas containing an Ar gas and a reducing gas is formed in the chamber, and the inner wall of the chamber is formed by the plasma. And / or a step of removing an adhering substance made of an AlF-based substance adhering to the surface of the member in the chamber, and subsequently supplying a precoating gas into the chamber to form a precoat film on the surface from which the adhering substance has been removed. A step of loading a target object into the chamber; and a step of supplying a film-forming gas into the chamber to perform a film-forming process on the target object. A film forming method is provided.

Further, according to the present invention, the CV
A plasma of a gas containing an Ar gas and a reducing gas is formed in a chamber where the D film formation process is performed, and the plasma is used to remove deposits adhered to the inner wall of the chamber and / or the surface of members in the chamber. Provided is a method for removing deposits.

Further, according to the present invention, a plasma of a gas containing an Ar gas and a reducing gas is formed in a chamber for performing a CVD film forming process after cleaning the inside of the chamber with a ClF ₃ gas. A adhered to the inner wall and / or the surface of the chamber inner member
Provided is a method for removing an attached substance, which comprises removing an attached substance comprising an IF-based substance.

According to the present invention, a plasma of a gas containing an Ar gas and a reducing gas is formed in a chamber for performing a CVD film forming process, and the plasma attached to the inner wall of the chamber and / or the surface of a member in the chamber is formed by the plasma. Since the attached matter is removed, the attached matter can be effectively removed without damaging the inner wall of the chamber and / or members in the chamber by the physical action of the Ar gas plasma and the chemical action of the reducing gas plasma. Film peeling can be made less likely to occur in the subsequent precoat treatment.

In particular, after the inside of the chamber is cleaned with ClF ₃ gas, an AlF-based material is deposited on the inner wall of the chamber and / or on the surface of the member in the chamber.
Since it is not removed by the F ₃ gas, it remains as an adhering substance, but by forming a plasma of a gas containing an Ar gas and a reducing gas in the chamber, the above-described physical action by the Ar gas plasma and the reducing gas plasma Can effectively remove the AlF-based deposits without damaging the inner wall of the chamber and / or the members in the chamber, and in the subsequent precoating process, film peeling due to the AlF-based deposits occurs. Can be difficult.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below by taking as an example a process of forming a Ti thin film by CVD. FIG. 1 is a sectional view showing an example of a CVD film forming apparatus. This film forming apparatus has a substantially cylindrical chamber 11 which is airtightly arranged, and includes therein a susceptor 12 for horizontally supporting a semiconductor wafer W as an object to be processed.
Are arranged in a state supported by the cylindrical support member 13. A guide ring 16 for guiding the semiconductor wafer W is provided at an outer edge of the susceptor 12.
A heater 14 is embedded in the susceptor 12, and the heater 14 is heated by a heater power supply 15 to heat the semiconductor wafer W, which is an object to be processed, to a predetermined temperature.

A shower head 20 is provided on a top wall 11 a of the chamber 11 via an insulating member 19.
The shower head 20 includes an upper block 20a, a middle block 20b, and a lower block 20c. The upper surface of the upper block 20a is provided with TiCl _4.
And a second introduction port 22 for introducing H ₂ as a reducing gas. In the upper block body 20a, a large number of TiCl ₄ passages 23 are branched from the first inlet 21 so that T
The iCl ₄ passage 23 communicates with the TiCl ₄ passage 25 formed in the middle block body 20b, and further communicates with the TiCl ₄ discharge hole 27 of the lower block body 20c. In the upper block body 20a, the second inlet 22
A number of H ₂ passages 24 are branched from the H ₂ passages 24.
There are communicated in _{H 2} passage 26 formed in the intermediate block body 20b, and communicates further communication in _{H 2} discharge holes 28 of the lower block body 20c. That is, the shower head 20
Is that TiCl ₄ and H ₂ are completely independent of chamber 11
It is of a matrix type supplied inside, and these are mixed after ejection to produce a reaction.

The first inlet 21 has a TiCl ₄ source 3
1 and the pipe 32 is connected which extends from the pipe 32 have pipe 36 extending from the Ar source 35 as a carrier gas is connected, TiCl ₄ gas from the TiCl ₄ source 31 is supplied through a pipe 36 Ar The carrier gas is supplied into the chamber 11 through the pipe 32. Further, a pipe 34 extending from a ClF ₃ source 33 for supplying ClF ₃ as a cleaning gas is connected to the pipe 32, and a ClF ₃ gas can be supplied into the chamber 11 through the pipe 34 and the pipe 32. It is possible. Wherein the second inlet 22 is connected to a line 38 extending from the source of _{H 2} 37, _{H 2} gas from the source of _{H 2} 37 is supplied into the chamber 11 via a pipe 38. In addition, piping 32,34,36,38 from each gas source has
Both are valve 39 and mass flow controller 4
0 is provided. Further, a switching valve 41 is provided in the pipe 34 near a connection portion of the pipe 32. Although not shown, a line for supplying N ₂ gas into the chamber 11 is also provided.

A high-frequency power supply 43 is connected to the shower head 20 via a matching unit 42. When high-frequency power is supplied from the high-frequency power supply 43 to the shower head 20, the chamber 1 is supplied through the shower head 20.
The gas supplied into 1 is turned into plasma, whereby the film forming reaction proceeds.

An exhaust pipe 44 is connected to the bottom wall 11b of the chamber 11, and an exhaust device 4 is connected to the exhaust pipe 44.
5 is connected. By operating the exhaust device 45, the pressure inside the chamber 11 can be reduced to a predetermined degree of vacuum.

With such an apparatus, T
To form an i-thin film, generally, first, a heater 14
Ar gas and H ₂ gas are introduced into the chamber 11 at a predetermined flow ratio while the inside of the chamber 11 is exhausted by the exhaust device 45 while the inside of the chamber 11 is exhausted while heating the inside of the chamber 11 to a predetermined temperature, and the inside of the chamber 11 is brought to a predetermined pressure. With
High-frequency power is supplied from the high-frequency power supply 43 to the shower head 20 to generate plasma in the chamber 11.

Next, while maintaining the flow rates of the Ar gas and the H ₂ gas, a predetermined flow rate of TiCl ₄ gas is supplied to the inner wall of the chamber 11 or a chamber internal member such as a shower head 20 disposed in the chamber 11. The surface of is pre-coated. This pre-coating treatment is preferably performed by setting the susceptor temperature to 500 to 700 ° C. and using TiCl ₄
0.001 to 0.01 L / min of gas, 0.5 to 5 L / min of H ₂ gas, and 0.06 to 0.7 L of Ar gas
/ Min flow rate. Further, if necessary, the surface of the precoat film is subjected to a nitriding treatment.

Thereafter, the semiconductor wafer W is loaded into the chamber 11 and heated to a predetermined temperature by the heater 14,
A gas is supplied under the same conditions as in the precoating process, and a film forming process of the Ti thin film is performed for a predetermined time. At this time, the film forming process of the Ti thin film is performed at a temperature of, for example, about 400 to 1000 ° C.

After the film formation, the semiconductor wafer W is carried out of the chamber 11. After performing such a film forming process on a predetermined number of semiconductor wafers, ClF ₃ gas as a cleaning gas is introduced into the chamber 11 to clean the inside of the chamber 11.

Conventionally, after such cleaning with ClF ₃ , a pre-coating process is performed under the same conditions as the film-forming process to form a pre-coating film of Ti on the chamber inner member such as the shower head 20 and the inner wall of the chamber 11. Thereafter, the semiconductor wafer W is loaded into the chamber 11 to perform a film forming process.

However, at the time of such cleaning, F generated by decomposition of the ClF ₃ gas reacts with Al constituting the chamber 11 to become an AlF-based material,
Since this AlF-based substance is deposited on the surface of the shower head 20 or the like and remains as an easily peelable deposit, A
There is a problem that the precoat film when the precoating treatment is performed is peeled off together with the AlF-based deposit when the IF-based deposit becomes thick.

In this embodiment, a series of processes from cleaning to Ti film formation are performed as shown in FIG. That is, the cleaning step (S
After STEP 1), pre-etching (STEP 2) is performed in the chamber 11 to remove AlF-based deposits adhered to chamber members such as the shower head 20 and inner walls of the chamber 11 at the time of cleaning, and then pre-coated (STEP 3). Is performed, the semiconductor wafer W is loaded into the chamber 11 (STEP 4), and a Ti film is formed on the semiconductor wafer W as described above (STEP 5).
Then, these processes are repeated.

FIG. 3 schematically shows the situation at the time of cleaning, removal of AlF-based deposits, and pre-coating.
As shown in FIG. 3A, at the time of cleaning in STEP 1, F generated by decomposing the ClF ₃ gas as described above reacts with Al constituting the chamber 11 to cause A to react.
lF-based material AlF _x becomes, AlF based deposits this AlF _x is for example deposited on the surface of such a shower head 20 50
Is formed. At this time, the flow rate of the ClF ₃ gas is 0.05
It is preferably in the range of 0.5 L / min.

As shown in FIG. 3B, during the pre-etching of STEP 2, an Ar source 35 and an H ₂ source 37 are used.
Supplies H ₂ gas as an Ar gas and a reducing gas into the chamber 11 via the shower head 20, and supplies high frequency power to the shower head 20 from the high frequency power supply 43 to form plasma of Ar gas and H ₂ gas. Then, with this plasma, the AlF-based deposits attached to the shower head 20 and the like are removed by etching. Similarly, when an AlF-based material adheres to the inner wall of the chamber 11 and other members in the chamber, for example, the susceptor 12 and the guide ring 16, the etching is also removed.

At this time, the physical
Not only the action but also the reducing gas H ₂By gas plasma
Chemical work as shown by the following chemical formula (1)
The inner wall of the chamber 11 and the shower head 20
Without damaging the chamber members such as
IF-based deposits can be effectively removed,
AlF-based deposits adhering to the surface of
Complete removal or significant reduction of any remaining
Can be. AlF_x+ H₂→ HF ↑ + Al (1) The valence is not considered in the above equation (1). And this
Assuming that equation (1) is a thermal reaction, ΔG of this reaction is +1
It becomes 212 kJ / mol.

The reducing gas is N ₂ instead of H _2.
H ₃ can also be used, in which case the following (2)
The reaction of the formula occurs. AlF _x + NH ₃ → HF ↑ + AlN (2) No valence is taken into account in the above equation (2), and ΔG is +274 kJ / mol assuming a thermal reaction.

H ₂ gas and NH ₃ gas can be used in combination as a reducing gas. In this case, a reaction represented by the following formula (3) occurs. AlF _x + NH ₃ + H ₂ → HF ↑ + Al + AlN (3)

In this pre-etching process, the Ar gas is preferably 0.1 to 0.6 L / min, and the flow rates of H ₂ gas and NH ₃ gas as the reducing gas are 0.5 to ₃ L / min and 0.1 to ₃ L / min, respectively. The pressure is preferably 15 to 1 L / min, and the pressure in the chamber is 133 to 93/93.
The pressure is preferably about 1 Pa (1 to 7 torr). Further, the high frequency power is preferably 200 to 800 W.

After the pre-etching process, the pre-coating process is performed as described above. As a result, a Ti precoat film is formed on the inner wall of the chamber 11 and the surface of the chamber inner member such as the shower head 20. At this time, Al
Since the F-based deposit is almost completely removed or significantly reduced, the precoat film 51 is formed almost directly on the surface of the shower head 20 or the like as shown in FIG. Therefore, peeling of the precoat film 51 hardly occurs.

Therefore, a sound film without defects can be formed without being affected by particles caused by film peeling in the subsequent CVD film forming process.

Next, a description will be given of an experiment in which the effect of actually performing the pre-etching process is understood. here,
After two cycles of cleaning → preetching (plasma treatment) → precoating were performed as one cycle, a by-product on the showerhead surface was peeled off from the tape to collect a sample, and the components were analyzed by SEM-EDX. For comparison, the components of by-products on the showerhead surface were analyzed in the same manner in the conventional treatment without pre-etching.

The cleaning was performed at a flow rate of 0.2 L / min of ClF ₃ gas at 250 ° C. for 3.9 hours each time.

In the pre-etching process, the Ar gas
L / min and the flow rates of H ₂ gas and NH ₃ gas as the reducing gas were 1.5 L / min and 0.5 L / min, respectively.
min and the pressure in the chamber is 665 Pa (5 Torr).
r), high-frequency power is output for 60 seconds at 500 W
The supplied plasma treatment was performed ten times to perform one pre-etching.

In the precoating process, the susceptor temperature was set to 650.
° C, and TiCl ₄ gas is supplied at 0.0046 L / mi.
n, H ₂ gas 1.5 L / min, Ar gas 0.3 L
The flow was performed for 45 minutes each time including a step of forming a Ti film by flowing at a flow rate of / min and nitriding the surface of the Ti film.

FIG. 4 shows the results. As shown in FIG. 4, in the case of the conventional processing without performing the pre-etching,
Many F and Al are detected, and A
Although it was confirmed that the 1F-based material remained, when pre-etching was performed, Al was hardly detected, and it was confirmed that the AlF-based material was almost completely removed.

In both the case where the pre-etching process of the present invention was performed and the case where the pre-etching process was not performed, after the actual film formation process was performed on a 200 mm Si wafer, the number of particles of 0.2 mm or more on the wafer surface Was measured. As a result, when the pre-etching process was not performed, the number of particles was 1000 or more, whereas when the pre-etching process was performed according to the present invention, the number of particles was 10 or less, and the film was peeled off. It was confirmed that the influence was extremely small.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above embodiment, the film forming process of the Ti film has been described as an example.
The present invention can also be applied to a film formation process of another film such as a film. Also,
Although the removal of the AlF-based deposit has been described as an example, it is also possible to remove a metal oxide film such as CuO, NiO, AlO, and SiO. Further, H _{2 is used} as a reducing gas.
Although the gas and the NH ₃ gas are used, the gas is not limited thereto, and may be a gas capable of reducing the deposit by a chemical action.

[0041]

As described above, according to the present invention,
Deposits attached to the inner wall of the chamber and / or the surface of the members in the chamber are removed by plasma of a gas containing an Ar gas and a reducing gas formed in the chamber where the CVD film forming process is performed. Due to the action and the chemical action of the reducing gas plasma, deposits can be effectively removed without damaging the inner wall of the chamber and / or members in the chamber, and the film is less likely to be peeled off in the subsequent precoating process. Can be.

In particular, after cleaning the inside of the chamber with ClF ₃ gas, an AlF-based substance is deposited on the inner wall of the chamber and / or on the surface of the member in the chamber.
Damage to the inner wall of the chamber and / or the members in the chamber due to the above-mentioned plasma action of the gas containing the Ar gas and the reducing gas formed in the chamber because it is not removed by the F ₃ gas but remains as a deposit. AlF-based deposits can be effectively removed without
In the subsequent precoating, film peeling due to the AlF-based deposits can be suppressed.

Therefore, in the subsequent CVD film forming process, a sound film free from defects due to particles can be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a CVD film forming apparatus used for carrying out the present invention.

FIG. 2 is a flowchart showing a series of processes from cleaning to Ti film formation.

FIG. 3 is a diagram schematically showing a state during cleaning, removal of AlF-based deposits, and pre-coating.

FIG. 4 is a diagram showing an effect in one embodiment of the present invention.

DESCRIPTION OF SYMBOLS 11; chamber 12; susceptor 13; support member 14; heater 16; guide ring 20; shower head 31; TiCl ₄ source 33; ClF ₃ source 35; Ar source 37; H ₂ source 43; Exhaust pipe 45; exhaust device 50; AlF-based deposit 51; pre-coated film W; semiconductor wafer

Claims (6)

[Claims] 1. A chamber in which a CVD film forming process is performed.
a step of forming a plasma of a gas containing an r gas and a reducing gas and removing deposits attached to the inner wall of the chamber and / or the surface of the members in the chamber by the plasma; and supplying a precoating gas into the chamber. Forming a pre-coated film on the surface from which the deposits have been removed; loading a workpiece into the chamber; supplying a film-forming gas into the chamber; C) comprising a step of performing a film treatment.
VD film forming method. 2. The inside of a chamber for performing a CVD film forming process is C
After cleaning with IF ₃ gas, A
forming a plasma of a gas containing an r gas and a reducing gas to remove deposits made of an AlF-based substance adhering to the inner wall of the chamber and / or the surfaces of the members in the chamber by using the plasma; Supplying a deposition gas to form a precoat film on the surface from which the deposits have been removed; loading a workpiece into the chamber; supplying a deposition gas into the chamber; Performing a film forming process on the processing body.
VD film forming method. 3. The reducing gas is H ₂ gas or NH ₃ gas.
3. The CVD film forming method according to claim 1, wherein the gas is a gas. 4. Prior to film formation, a plasma of a gas containing an Ar gas and a reducing gas is formed in a chamber for performing a CVD film formation process, and the plasma adheres to the inner wall of the chamber and / or the surface of a member in the chamber. A method for removing extraneous matter, comprising removing extraneous matter. 5. The inside of a chamber for performing a CVD film forming process is C
After cleaning with IF ₃ gas, A
A plasma of a gas containing an r gas and a reducing gas is formed, and the plasma is used to remove an adhering substance made of an AlF-based substance adhering to an inner wall of the chamber and / or a surface of a member in the chamber. Method. 6. The reducing gas is H ₂ gas or NH ₃ gas.
The method for removing deposits according to claim 4 or 5, wherein the method is a gas.