JPH10317142A - Cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove the titanium chloride without using any plasma by using the ClF gas as the cleaning gas in a condition where the inside of a treatment container is heated at the prescribed temperature when the titanium chloride deposit on the inside of the treatment container is removed in forming a film on a substrate. SOLUTION: The ClF gas from a ClF3 gas source 70 is used as the cleaning gas in a condition where the inside of a treatment container 4 is heated to >=130 deg.C. The treatment container 4 is provided with a shower head part to supply the gas thereinto, and at least the shower head part is heated to >=130 deg.C. The pressure in the treatment container 4 is in the range from 100 m Torr. to 1 Torr., and the ClF gas to be used is any one of ClF gas, ClF3 gas or ClF5 gas. The titanium chloride M of the shower head part which can be a major cause of generating particles can be rapidly and approximately completely removed.

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 film forming apparatus for forming a film on a substrate such as a semiconductor wafer.

[0002]

2. Description of the Related Art In general, in order to manufacture a semiconductor integrated circuit, a large number of desired elements are formed by repeatedly performing film formation and pattern etching on a substrate such as a semiconductor wafer. . By the way, as a wiring connecting each element, a contact metal for making an electrical contact to each element, or a barrier metal used as a measure for suppressing the absorption of Si from the substrate, it is needless to say that the electric resistance is low. Materials with excellent corrosiveness must be used. As materials that can meet such demands, high melting point metal materials such as Ti (titanium), W (tungsten), and Mo (molybdenum) tend to be used. Among them, properties such as electrical and corrosion resistance are particularly high. In particular, Ti and the nitride film TiN
(Titanium nitride) tends to be frequently used.

[0003] In general, a Ti film is made of T
Plasma CVD (Chemical Vapor Depo) using iCl ₄ (titanium tetrachloride) gas and hydrogen gas
In this case, titanium chloride as a reaction by-product considerably adheres to the inside of the processing container during the film forming process. The reaction by-products cause particle problems such as peeling off during processing, so that a cleaning process is performed regularly or irregularly to avoid problems such as particles, and the reaction by-products are removed. Removal is performed.

[0004]

In order to remove titanium chloride adhering to the inside of the processing container, generally, an NF-based gas, for example, NF ₃ gas is used as a cleaning gas to generate plasma in the processing container. The NF ₃ gas is decomposed by the plasma to become active seeds and the attached titanium chloride is etched. However,
In the cleaning method using plasma as described above, for example, reaction by-products adhering to a mounting table or the like on which a wafer is mounted can be removed to some extent, but the reaction by-products in a portion away from the plasma can be sufficiently removed. However, there is a problem that it cannot be removed or it takes a long time to remove. In particular, there is a problem that a relatively large amount of reaction by-products tends to adhere, and furthermore, it is difficult to remove the adhesion-producing portion of the shower head portion, which is likely to peel off the film and is a major cause of particles.

[0005] The present invention focuses on the above problems,
It was created to solve this effectively. An object of the present invention is to provide a cleaning method capable of efficiently removing reaction by-products composed of titanium chloride without using plasma.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a cleaning method for removing titanium chloride adhered in a processing vessel for forming a film on a substrate. Is heated to 130 ° C. or higher, and the titanium chloride is removed using a ClF-based gas as a cleaning gas.

As described above, Cl is used as the cleaning gas.
Use F-based gas, and set 13
By heating to 0 ° C. or higher, it becomes possible to remove a reaction by-product composed of titanium chloride without using plasma. In this case, by cleaning the shower head portion where it is difficult to remove the attached reaction by-products, in particular, in a state where the shower head portion is heated to 130 ° C. or more, the titanium chloride adhering to the shower head portion is efficiently removed. can do. The pressure at the time of this cleaning is preferably, for example, in the range of 100 mTorr to 1 Torr.
Examples of the ClF-based gas include ClF gas and ClF gas.
F ₃ gas, ClF ₅ gas, or the like can be used.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the cleaning method according to the present invention will be described below in detail with reference to the accompanying drawings. FIG.
FIG. 2 is a configuration diagram showing a film forming apparatus to be cleaned. The film forming apparatus 2 includes a processing container 4 formed into a cylindrical shape by, for example, aluminum, the inside of which is anodized, and the processing container 4 is grounded. A power supply line insertion hole 8 is formed in the center of the bottom 6 of the processing container 4 and an exhaust port 10 is provided in the periphery thereof. An exhaust system 12 is connected so that the inside of the container can be evacuated.

A disc-shaped mounting table 14 made of a non-conductive material, for example, alumina, is provided in the processing vessel 4. A hollow cylindrical leg extending downward is provided at the center of the lower surface of the mounting table 14. A lower end of the leg 16 is hermetically attached and fixed to the periphery of the feeder line insertion hole 8 of the container bottom 6 with a bolt 20 or the like via a sealing member 18 such as an O-ring. Is done. The mounting table 14 includes, for example,
A resistance heating element 22 made of carbon coated with SiC is embedded, and a semiconductor wafer W as a substrate placed on the upper surface side can be heated to a desired temperature. An upper portion of the mounting table 14 is configured as a thin ceramic electrostatic chuck 26 in which a chuck electrode 24 made of a conductive plate such as copper is embedded, and the Coulomb force generated by the electrostatic chuck 26 is used. The wafer W is held by suction on the upper surface.

The resistance heating element 22 is connected to a power supply section 30 via an insulated power supply lead wire 28. A high-voltage DC power supply 34 is connected to the chuck electrode 24 of the electrostatic chuck 26 via an insulated power supply lead wire 32.
Connected to. At a predetermined position in the periphery of the mounting table 14,
A plurality of lifter holes 36 are provided to penetrate in the vertical direction, and wafer lifter pins 38 are accommodated in the lifter holes 36 so as to be able to move up and down in the vertical direction.
By lifting and lowering the lifter pins 38 by a lifting mechanism (not shown) at the time of unloading, the wafer W is lifted or lowered.

A ceiling plate 42 integrally provided with a shower head 40 is hermetically attached to the ceiling of the processing vessel 4 via a sealing member 44 such as an O-ring. Reference numeral 40 denotes a processing space S which is provided so as to face substantially the entire upper surface of the mounting table 14 so as to face the mounting table 14 and forms a processing space S with the mounting table 14. The shower head 40 is for introducing a processing gas into the processing container 4 in a shower shape, and is provided with an ejection surface 46 on the lower surface of the shower head 40.
Are formed with a large number of injection holes 48 for discharging the processing gas. An insulating material 50 is interposed in the mounting portion of the ceiling plate 42 and is insulated from the processing container 4.

The ceiling plate 42 is provided with a gas introduction port 52 for introducing a processing gas into the shower head section 40, and a supply passage 54 for flowing various gases is connected to the introduction port 52. A diffusion plate 58 having a large number of diffusion holes 56 is provided in the shower head 40 for the purpose of diffusing the gas supplied from the supply passage 54. Further, a cooling jacket 60 for cooling the temperature of this portion at the time of film formation and a heater 62 made of, for example, a resistance heating element for heating this portion to a predetermined temperature at the time of cleaning are provided on the side wall of the head.

[0013] the supply passage 54, as a gas for film formation, such as H ₂ gas source 68 for storing the TiCl ₄ gas source 64, the H ₂ gas for storing the TiCl ₄ gas is connected via a branch pipe On the other hand, a ClF-based gas such as ClF
A ClF ₃ gas source 70 for storing _three gases is connected via a branch pipe. Further, for example, an Ar gas source 74 is also connected to the supply passage 54 to supply an inert gas. The flow rate of each gas is controlled by a flow controller, for example, a mass flow controller 72 provided in each branch pipe.
Is controlled by Here, when forming a Ti film on the substrate surface, the film is formed by plasma CVD using TiCl ₄ gas, H ₂ gas and Ar gas.

A matching circuit 77 and a high-frequency power source 78 for 13.56 MHz plasma, for example, are connected to the ceiling plate 42 via lead wires 76 in order to form plasma during the Ti film formation. In addition, a cooling jacket 80 through which a coolant flows, for example, for cooling the wall surface is provided on a side wall of the processing container 4, and a gate valve 82 that is opened and closed when a wafer is loaded and unloaded is provided on a part of the side wall of the container 4. Provided.

Next, a cleaning method according to the present invention, which is performed by using the apparatus configured as described above, will be described. According to the cleaning method of the present invention, a chlorine compound as a reaction by-product adhering to the inside of the container when a Ti film is formed is converted into C
The removal is performed by using an IF gas and maintaining the temperature in the container at 130 ° C. or higher. First, the film formation will be described. For example, when forming a Ti film on the surface of the substrate W,
TiCl ₄ gas, H ₂ gas, and Ar gas are respectively supplied as a film forming gas from the shower head unit 40 into the processing vessel 4 at a predetermined flow rate, and at the same time, a high frequency is supplied from the high frequency power supply 78 to the shower head unit 40. The voltage is applied to between the mounting table 14. As a result, plasma is generated in the processing space S, and TiCl ₄ reacts with H ₂ to be reduced, so that a Ti film is formed on the substrate. The deposition conditions at this time are, for example, a substrate temperature of about 550 ° C. and a process pressure of 1 Torr.
r and the plasma power is about 500 W.

[0016] Such a film forming process is performed simultaneously with hydrochloric acid (HCl) and titanium chloride (TiClx: X = 2 to 2).
3) and the like, and HCl is discharged as a gas. However, titanium chloride is difficult to be discharged because its vapor pressure is considerably low, and tends to adhere to the inner wall of the processing container 4 and the like. Jetting surface 46 which is the lower surface of the shower head
For example, a large amount of titanium chloride M adheres depending on the number of processed sheets.

After the film forming process has been performed on a plurality of wafers in this way, a cleaning process for removing the attached titanium chloride is performed. During this cleaning, a ClF-based gas, here a ClF ₃ gas, is supplied as a cleaning gas from the shower head unit 40 into the processing container 4 at a predetermined flow rate, for example, 100 sccm, and the temperature inside the container is maintained at 130 ° C. or higher. I do.
In order to increase the temperature of the shower head 40, the heater 62 incorporated therein may be energized. In this case, the mounting table 14 can be maintained at a high temperature of, for example, 500 ° C. or more due to its structure. However, the temperature of the shower head section 40 cannot be so high due to its structure. It is set within a range of up to about 180 ° C., which is the value.

If the shower head 40 can withstand a temperature higher than 180 ° C. due to structural improvement, it may be heated to the upper limit temperature.
At this time, the pressure in the container is 1 Torr, and cleaning is performed, for example, for about 60 minutes. At the time of this cleaning processing, cleaning by heat is performed without using plasma. By the cleaning process using such ClF ₃ gas, the titanium chloride adhering to the inside of the processing vessel 4 becomes TiF ₄ having a higher vapor pressure.
(Titanium tetrafluoride), and evaporation or sublimation is promoted and removed. In particular, TiF ₄ is 130
Since the evaporation starts at about ℃, the shower head 40
By heating this to about 130 ° C. or more during cleaning by the heater 62 incorporated therein, it is possible to relatively easily and quickly remove the attached titanium chloride M.

FIG. 2 shows TiCl ₄ (source gas) and TiC
l ₃ is a graph showing the relationship between each of the temperature and vapor pressure of (reaction byproduct) and TiF _4. As is clear from the graph, by heating the portion to be cleaned to 130 ° C. or higher using a ClF-based gas as a cleaning gas as in the present invention, TiCl ₃ which does not evaporate unless it is at about 700 ° C. (Reaction by-product)
Can be converted to TiF ₄ , which starts to evaporate at about 130 ° C., and this can be removed by evaporation. FIG. 3 is a graph showing the cleaning state of the mounting table and the shower head when the cleaning process is performed using the method of the present invention, and the cleaning temperature is variously changed. In the figure, a black mark indicates that titanium chloride could not be removed, and a white mark indicates that titanium chloride could be removed. still,
The cleaning condition at this time is that the process pressure is 1000
mTorr, the flow rate of ClF ₃₁ gas is 100 sccm,
The cleaning time is 30 minutes.

As apparent from the graph, the titanium chloride adhering to the mounting table became a white powder at room temperature (about 200 ° C.) and could not be sufficiently removed.
When the temperature of the mounting table was raised to 200C and 200C, it could be completely removed. Also, the titanium oxide adhered to the shower head was turned into white powder and could not be sufficiently removed even when the shower head was heated to about 110 ° C. by a heater as well as at room temperature. , 1
As a result of cleaning by heating at 30 ° C., 150 ° C., and 180 ° C., titanium chloride could be almost completely removed.

As described above, according to the present invention, in particular, the titanium chloride adhering to the shower head, which mainly causes particles, is heated to 130 ° C. or more to remove C
If 1F ₃ gas is used, it can be almost completely removed. Further, when the process pressure during cleaning was examined, a graph showing the relationship between the temperature and the cleaning amount as shown in FIG. 4 was obtained. In other words, it has been found that the cleaning efficiency is most efficient when the process pressure is about 500 mTorr, and it is preferably performed within the range of 100 mTorr to 1 Torr.

The reason is that the process pressure is 100 mTo
If it is lower than rr, the amount of ClF ₃ gas is too small and T
If the conversion reaction to iF ₄ is not sufficiently performed and the process pressure is higher than 1 Torr, the amount of ClF ₃ gas increases, but conversely, the vaporization of TiF ₄ is suppressed, and as a result, In both cases, it is considered that the cleaning efficiency is reduced. Although the cooling jacket 60 and the heater 62 are provided in the shower head section 40 here, instead of this, for example, a temperature control mechanism that can selectively flow a chiller of a high-temperature heat medium and a low-temperature refrigerant is provided. The one temperature control mechanism may have two functions of cooling and heating.

Here, ClF ₃ gas is used as ClF-based gas.
Although the case of using gas has been described as an example, it is needless to say that ClF gas, ClF ₅ gas, or a mixed gas thereof having the same effect may be used. The substrate is not limited to a semiconductor wafer, but may be a glass substrate, an LCD, or the like.
Of course, it can be applied to a substrate or the like.

[0024]

As described above, according to the cleaning method of the present invention, the following excellent functions and effects can be exhibited. By cleaning with a ClF-based gas in a state where the inside of the processing vessel is heated to 130 ° C. or more, titanium chloride can be efficiently removed, and no plasma is used because plasma is not used. Cleaning can be performed to every corner. In particular, by incorporating a heater in the shower head and heating it to 130 ° C. or higher, titanium chloride in the shower head, which is a main cause of generation of particles, can be quickly and almost completely removed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a film forming apparatus to be cleaned.

FIG. 2 is a graph showing the relationship between the respective temperatures and vapor pressures of TiCl ₄ (source gas), TiCl ₃ (reaction by-product), and TiF ₄ .

FIG. 3 is a graph showing a cleaning state of a mounting table and a shower head when a cleaning process is performed using the method of the present invention.

FIG. 4 is a graph showing a relationship between cleaning temperature and cleaning efficiency.

[Explanation of symbols]

2 Film forming apparatus 4 Processing container 14 Mounting table 40 Shower head part 42 Ceiling plate 46 Injection surface 48 Injection hole 62 Heater 64 TiCl ₄ gas source 66 NH ₃ gas source 70 ClF ₃ gas source 78 High frequency power supply M Titanium chloride W Semiconductor Wafer (substrate)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/285 H01L 21/302 N

Claims (4)

[Claims] 1. A cleaning method for removing titanium chloride adhered in a processing vessel for forming a film on a substrate, wherein a ClF-based gas is used as a cleaning gas while the processing vessel is heated to 130 ° C. or higher. A cleaning method, wherein the titanium chloride is removed by a cleaning method. 2. The cleaning method according to claim 1, wherein the processing vessel has a shower head for supplying a gas therein, and at least the shower head is heated to 130 ° C. or higher. 3. The pressure in the processing container is 100 mTo.
3. The cleaning method according to claim 1, wherein the temperature is within a range of rr to 1 Torr. 4. The ClF-based gas comprises ClF gas, ClF gas,
4. The cleaning method according to claim 1, wherein the cleaning method is one of F ₃ gas and ClF ₅ gas.