JPH11140652A - Method for cleaning stuck metallic film in thin film forming treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To beautifully remove metallic film such as metallic copper stuck to the inside of a thin film forming device without generating particles and the peeling of the coating. SOLUTION: This cleaning method is executed in a thin film forming device 10 in which metallic film is deposited on the surface of a substrate and is composed of a cleaning process of an oxidizing stage in which metallic film 19 stuck to the inside of the thin film forming device at the time of thin film formation is oxidized to made the oxidized coating thereof, a complexing stage in which the oxidized coating is complexed to make the complex thereof and a sublimating stage in which the complex is sublimated, and the conditions of the cleaning process are set so as to regulate the oxidizing stage to the rate-determining one.

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 an adhered metal film in a film forming apparatus, and more particularly to a method for removing metal copper and the like adhered inside the film forming apparatus during film formation.

[0002]

2. Description of the Related Art As a cleaning method for removing metallic copper, for example, a chemical vapor etching method is conventionally known. Looking at the process of the chemical vapor etching method from a microscopic point of view, a process of oxidizing metallic copper to produce copper oxide (oxidizing process of metallic copper) and a complex of copper oxide to form a copper complex. It can be divided into three steps of a production step (copper oxide complexing step) and a sublimation step of the copper complex (copper complex sublimation step). In the cleaning method including these steps, a chemical reaction occurs in the order of a copper metal oxidation step, a copper oxide complexation step, and a copper complex sublimation step, and the metal copper is removed by chemical vapor etching.

[0003] As a conventional literature on chemical vapor etching, Japanese Patent Publication No. 7-93289 (Document 1), A. Ja
in, TTKodas, and MJHampden-Smith SPIE2335 (199
4) p52 (Reference 2), MAGeorge, DWHess, SEBec
k, JCIvankovits, DABohling, and APLane J. El
ectrochem. Soc. 142 (1995) p961 (Reference 3), MJHampd
en-Smith, TTKodas, MRS Bulletin / June 1993 p39
(Reference 4).

[0004] Document 1 relates to a vapor phase etching method of a metal thin film on a substrate used for manufacturing an integrated circuit, and relates to an effective amount of β-diketone or the like in which the metal surface of the metal thin film is dispersed in an oxidizable atmosphere; The metal-ligand complex is contacted under conditions capable of forming a volatile metal-ligand complex, and the metal-ligand complex is volatilized to etch the metal surface. The metal to be etched includes copper. An example is shown in which oxygen (O ₂ ) is used for metal oxidation and hexafluoroacetylacetone is used as the β-diketone. Reference 2 describes an example in which H ₂ O ₂ is used to oxidize copper metal and hexafluoroacetylacetone is used to complex copper oxide. Reference 3
Now, use O ₂ remote plasma to oxidize copper metal,
An example of using hexafluoroacetylacetone for complexing copper oxide has been described. Literature 4 discloses a method of cleaning metallic copper using an oxidizing atmosphere and hexafluoroacetylacetone, which is a kind of β-diketone, as an example of a technique for etching metallic copper.

As described above, regarding the chemical vapor etching method, conventionally, as a method of oxidizing metallic copper, H is used.
Methods using ₂ O ₂ , O ₂ remote plasma, and O ₂ have been known. As a raw material for complexing copper oxide, β-
Hexafluoroacetylacetone which is a kind of diketone (1,1,1,5,5,5-hexafluoro-2.4-
It has been known that pentanedione) is frequently used.

[0006]

When the step of forming a metal copper film on a substrate surface by a film forming apparatus is repeated continuously for each substrate while replacing the substrate, the metal film is formed inside the film forming apparatus. Copper film adheres. When the film attached inside the film forming apparatus becomes thick, a problem such as film deterioration occurs in the film forming process. Therefore, it is necessary to carry out a cleaning process for removing the adhered film at an appropriate timing.

However, conventionally, as described in the above documents, a cleaning method for removing a copper thin film on a substrate is mainly used. The cleaning method for removing a metal copper film adhered to the inside of a film forming apparatus is known. Had not been proposed.

Therefore, the present inventors have tried to remove metallic copper adhering to the inside of the film forming apparatus by applying the chemical vapor etching method described in the above-mentioned reference 1. That is, according to the chemical vapor etching method of Reference 1, copper metal is oxidized using oxygen to form copper oxide, and the copper oxide is complexed using hexafluoroacetylacetone to form a copper complex. The complex sublimed.
However, according to the chemical vapor etching method according to the method described in Document 1, the adhered metallic copper film becomes sponge-like (porous) and cannot be removed cleanly, and on the contrary, remains as particles. There was a problem or a cavity was formed on the lower surface side of the adhered film, and as a result, the adhered film was cracked and the film was peeled off. FIGS. 3 and 4 show the state of the sponge-like adhered film,
The state of film peeling is shown in the photographs of FIG. 5 and FIG.

As described above, even when the conventional chemical vapor etching method is used, the metal copper film adhered to the inside of the film forming apparatus cannot be removed cleanly. Most recently, Mark A. George, Alan J. Kobar, Scott E. Beck, Jen
Waskiewcz, Ron M. Pearlstein, and David A. Bohling
“Chemical Vapor Etching of Copper for Cu CVD Cham
ber Cleaning ”Advanced Metallizationand Interconn
ect Systems for ULSIApplications in 1997 (US sess
ion: September 30, 1997). According to this document, research reports have been made on a cleaning method for removing metallic copper adhered in a film forming apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to remove a metal film such as copper metal adhered inside a film forming apparatus without generating particles or film peeling.
An object of the present invention is to provide a cleaning method that can be removed neatly.

[0011]

A method of cleaning a deposited metal film in a film forming apparatus according to the present invention is configured as follows in order to achieve the above object.

The cleaning method according to the present invention is based on the premise that the metal film deposited on the inside of the film forming apparatus at the time of film formation is formed by depositing the metal film on the surface of the substrate.
It is configured to be removed by a cleaning process including an oxidation process of oxidizing the metal film to form an oxide film, a complexing process of complexing the oxide film to form the complex, and a sublimation process of sublimating the complex. ing.

The first cleaning method is characterized in that, in the cleaning method having the above-described configuration, the conditions of the cleaning step are set so that the oxidation step is a rate-determining step.

In the second cleaning method, preferably, the metal film is metallic copper, and copper oxide is formed in an oxidation step, copper oxide is complexed in a complexing step to form a copper complex, and further, an oxidation step is performed. It is characterized in that the conditions of the cleaning process are set so as to be a rate-determining process.

In a third cleaning method, the conditions of the cleaning step in which the oxidation step is the rate-determining step are set by creating an atmosphere capable of complexing and then creating an atmosphere capable of oxidation. It is characterized by.

A fourth cleaning method is characterized in that, in the above method, the conditions of the cleaning step in which the oxidation step is a rate-determining step are set by simultaneously creating a complexable atmosphere and an oxidizable atmosphere. I do.

A fifth cleaning method is the above-mentioned method, wherein the copper complex is preferably a β-diketone complex prepared using β-diketone.

A sixth cleaning method is the above-mentioned method, wherein preferably, the oxidizable atmosphere is created by introducing oxygen into the film forming apparatus.

A seventh cleaning method is the above method, and preferably, the complexable atmosphere is created by introducing β-diketone into a film forming apparatus.

An eighth cleaning method is the same as the above, and preferably uses hexafluoroacetylacetone as the β-diketone.

The ninth cleaning method is characterized in that, in the above method, preferably, the reaction in the oxidation step does not proceed excessively more than the reaction in the complexing step. The maximum value of the reaction rate of the complexing step is determined by the rate of formation of copper oxide generated by the oxidation step, but the reaction of the oxidation step does not proceed excessively so that the oxidation step underlying the complexing step is a rate-limiting step Is preferred.

[0022] A tenth cleaning method is the above method, preferably characterized in that the exhaust speed is intermittently changed during the cleaning step.

The eleventh cleaning method is the above-mentioned method. Preferably, the film forming apparatus is a CVD film forming apparatus having a gas introduction guide having a horn stream structure in a space in front of the substrate. Is characterized by being metallic copper mainly attached to the substrate facing surface of the gas introduction guide.

The twelfth cleaning method is the above method, preferably when the oxidizable atmosphere in the oxidation step is made of oxygen and the complexable atmosphere in the complexing step is made of β-diketone. During the cleaning step, the temperature inside the film forming apparatus is a temperature included in the range of 100 to 400 ° C., and the pressure inside the film forming apparatus is 100 mTorr to oxygen partial pressure.
It is characterized by 300 Torr.

The thirteenth cleaning method is the above method, preferably when the oxidizable atmosphere in the oxidation step is made of oxygen and the complexable atmosphere in the complexing step is made of β-diketone. The flow rate of oxygen is not more than 5 times the flow rate of β-diketone in the film forming apparatus in molar ratio.

[0026]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a film forming apparatus in which a cleaning method according to the present invention is performed. In the film forming apparatus 10, a substrate holder 12
Is provided. During film formation, a substrate to be formed is placed on the substrate holder 12. A gate valve 13 for taking a substrate in and out, and an exhaust system 14 for evacuating the inside of the vacuum vessel 11 to a required vacuum state are provided, for example, on a peripheral side wall of the vacuum vessel 11. A main valve 16 is attached to a pipe 15 connecting the exhaust system 14 and the vacuum vessel 11. A heater 17 is arranged outside each of the peripheral side wall, the top wall, and the bottom wall of the vacuum vessel 11. The heater 17 maintains the temperature of the vacuum vessel 11 at a predetermined temperature. A heater 18 is also built in the substrate holder 12 so that the substrate holder 12
And the substrate is kept at a predetermined temperature. A power supply for supplying heating power to the heaters 17 and 18 and a sensor unit for detecting temperature are not shown.

The vacuum vessel 11 essentially constitutes a film forming apparatus for depositing a metal film such as copper metal on the substrate surface. Sputtering, CV
Any method such as D can be applied. At the time of film formation, the substrate is carried in via the gate valve 13 and placed on the substrate holder 12. Thereafter, the inside of the vacuum chamber 11 is maintained at a required reduced pressure suitable for film formation by the exhaust system 14. In this state, a film forming process is performed on the surface of the substrate. Film formation on a substrate is performed continuously on a plurality of substrates, for example, in a single wafer system. In practice, the vacuum vessel 11
, A configuration of a film forming apparatus required according to the film forming method is added. In the case of sputtering, a target or an electrode for generating plasma is provided, and in the case of CVD, a structure for introducing a reaction gas or the like to cause a chemical reaction or the like is provided. In the film forming apparatus shown in FIG. 1, the illustration of the configuration related to film formation is omitted.

In the present embodiment, in the film forming apparatus 10, as a result of the continuous film formation of the substrate, an adhered film (such as metallic copper) adhered to the inside of the vacuum vessel 11 (around the wall surface of the vacuum vessel, piping, and the substrate holder). The cleaning step for removing the attached metal film 19 will be described as a subject. In this cleaning step, the attached film 19 is removed using chemical vapor etching. Although FIG. 1 shows the adhesion film 19 attached to a part of the inner surface of the vacuum container 11 and a part of the outer surface of the substrate holder 12, the adhesion film is actually formed on the inner surface of the vacuum container 11 and the substrate holder 12. It is attached to the outer surface of the vacuum chamber 11.

An oxygen supply system 21 and a β-diketone supply system 22 are provided for a vacuum vessel 11 as an apparatus for performing a cleaning process based on chemical vapor etching according to the present embodiment. The oxygen supply system 21 is connected to the vacuum vessel 11 via a pipe 23 via a valve 23, and the β-diketone supply system 22 is connected to the vacuum vessel 1 via a pipe 26 via a valve 25.
Connected to 1. In the β-diketone supply system 22, bubbling is performed using, for example, nitrogen (N ₂ ) to vaporize the β-diketone. Other methods of vaporizing liquid β-diketone include a method of vaporizing a liquid using a vaporizer (measurement technology '97, 10, p21 to 24), and a method of using a container containing β-diketone such as a chiller. There is a method of warming from the outside at a constant temperature by a heating mechanism (the same document, p22, FIG. 2).
Thus, the vaporized β-diketone is introduced into the vacuum vessel 11. With this configuration, during the cleaning process,
Oxygen (O ₂ ) and β-diketone in the vacuum vessel 11
It is introduced under the appropriate cleaning conditions described below. Here, the most preferred β-diketone is hexafluoroacetylacetone.

When the cleaning process according to the present embodiment utilizing chemical vapor etching is performed in the film forming apparatus 10, the metal copper film 19 adhered to the inside is sequentially and smoothly etched from the surface thereof. For this purpose, the cleaning conditions are set so as to satisfy the following conditions. Hereinafter, the conditions of the cleaning process will be described separately for the first and second embodiments.

Embodiment 1 In the film forming apparatus 10, film formation (metal copper) on a plurality of substrates is performed continuously. After the formation of the last substrate is completed, the gate valve 1 of the vacuum vessel 11 is
3 is opened and the substrate is taken out. In this state, a metal copper film 19 having a thickness of about 2 μm is adhered inside the vacuum vessel 11. Thereafter, the gate valve 13 is closed and the heater 1 is closed.
The temperature of the vacuum vessel 11 and the substrate holder 12 and the like is preferably kept at 210 ° C. by 7 and 18, and the inside of the vacuum vessel 11 is kept at a high degree of vacuum by opening the main valve 16 and operating the exhaust system 14. Thereafter, the main valve 16 is closed.

In the above state, first, the valve 25 is opened, and the vaporized β-diketone is introduced into the vacuum vessel 11. Here, hexafluoroacetylacetone (Hhfac) was used as the β-diketone. At this time, the flow rate of N ₂ used for bubbling was 140 sccm, and the flow rate of hexafluoroacetylacetone was 40 sccm.

After introducing β-diketone into the vacuum vessel 11, three minutes later, with the internal pressure at about 20 Torr, the valve 23 is opened, and oxygen is supplied at a flow rate of 20 sccm to the vacuum vessel 11.
Introduce within. After that, the main valve 16 is opened, and the pressure in the vacuum vessel 11 is controlled to 20 Torr by the exhaust system 14. When oxygen is introduced into the vacuum vessel 11, the β-diketone is in a state of being sufficiently supplied into the vacuum vessel 11.

Four minutes after the introduction of oxygen, valves 23 and 25
Is closed, and the introduction of β-diketone (hexafluoroacetylacetone) and oxygen is stopped. The internal pressure of the vacuum vessel 11 is controlled to a preferable pressure state by controlling the exhaust operation of the exhaust system 14. As a result, it was confirmed that the metal copper film 19 attached to the inside of the vacuum vessel 11 was completely removed. Thereby, the cleaning process was completed.

In the above description of the cleaning step, the description has been given in terms of the operation procedure. The heating operation of the heaters 17 and 19, the exhaust operation in the vacuum vessel 11 by the exhaust system 14 with the main valve 16 opened, and the β operation by opening the valve 25
Control of introduction of diketone, introduction of oxygen by opening valve 23, and the like are performed according to a controller (not shown).

What is important in the above operation procedure is that a sufficient amount of β-diketone is supplied into the vacuum vessel 11 at the stage when oxygen is introduced into the vacuum vessel 11. As a result, a cleaning condition is set such that the oxidation step of metal copper by oxygen becomes a rate-determining process.

Next, the above-mentioned cleaning step will be described from a micro viewpoint of a chemical reaction. Looking at the cleaning process of metal copper using the above-described chemical vapor etching method from a microscopic viewpoint, as already described in (conventional technology),
It consists of a metal copper oxidation step, a copper oxide complexation step, and a copper complex sublimation step. These steps are represented by chemical formulas as follows.

[0039]

Embedded image Oxidation step: 2Cu + O ₂ → 2CuO 4Cu + O ₂ → 2CuO ₂

[0040]

Embedded image Complexing step: CuO + 2Hhfac → Cu (hfac) ₂ + H ₂ O Cu ₂ O + 2Hhfac → Cu (hfac) ₂ + H ₂ O
+ Cu

Sublimation step: Sublimation of Cu (hfac) ₂ adhering to the surface

In the above, a chemical reaction takes place in the order of the step of oxidizing copper metal, the step of complexing copper oxide, and the step of sublimating copper complex. That is, in the above-mentioned cleaning step, the existence of the oxidation step is premised on the complexing step, and the existence of the complexing step is presupposed on the sublimation step. In the cleaning according to the first embodiment,
By setting the conditions so that the oxidation process of metal copper by oxygen becomes the rate-determining process, the complexing process and sublimation process are promoted, and the metal copper film attached inside the vacuum vessel can be etched smoothly from the surface. I have to. Here, “the oxidation process of metallic copper by oxygen becomes a rate-determining process” means that the chemical reaction of the oxidation process proceeds at the slowest rate in the above three chemical reactions. The reaction rate of the oxidation step determines the reaction rate of the complexing step and the reaction rate of the sublimation step, and as a result, the reaction rate of the entire cleaning step. In other words, the cleaning method using the chemical vapor etching according to the present invention sets the cleaning conditions so that the reaction of the oxidation process of copper metal does not proceed excessively as compared with the reaction of the complexing process. It can also be said that.

According to the operation procedure of the above-described cleaning step, the vacuum vessel is not filled before oxygen is introduced into the vacuum vessel 11, that is, before an oxidizable atmosphere is created in the vacuum vessel 11. Since a complexable atmosphere is formed in the inside of the metal 11, when the oxidizing action of metallic copper by oxygen occurs, the complexing process proceeds immediately, the sublimation process further proceeds, and the copper complex is exhausted. Is done. Therefore, the reaction in the oxidation process of metallic copper does not proceed excessively as compared with the reaction in the complexing process, and the oxidation process is a rate-determining process.

As described above, according to the cleaning method of the first embodiment, the conditions are set so that the oxidation step of metal copper by oxygen is a rate-determining step. And can be removed by etching smoothly.

Next, the exhaust operation in the above cleaning step will be described in detail. In the cleaning process, the evacuation operation of the evacuation system 14 is appropriately controlled. Preferably vacuum vessel 11
By intermittently changing the exhaust capacity in the chamber, the sublimation step and the like are further advanced, the removal rate of the copper complex from the adhered film is increased, and the efficiency of the cleaning step is increased.

In the above cleaning step, the removal efficiency may be reduced for the following two reasons. First, when the time of the cleaning treatment elapses, the gas partial pressure of the copper complex in the vicinity of the surface of the adhered metallic copper increases, and the sublimation speed is reduced, so that the sublimation process may eventually become a rate-determining process.
Second, similarly, as the time elapses, the gas partial pressure of the copper complex near the surface of the adhered metallic copper increases, and the partial pressure of oxygen near the copper surface decreases, so that the oxidation rate of metallic copper decreases. There is a risk of doing too much.

The case of the first reason will be described in detail. If the evacuation speed is reduced because the internal pressure is to be kept high at the same flow rate by introducing the gas into the vacuum vessel, the reaction product is not exhausted, and the reaction product stays in the vacuum vessel for a long time,
Under certain conditions (when the pumping speed is too low), the proportion of reaction products in the vacuum vessel increases with time.
That is, the partial pressure of the reaction product increases, and the sublimation rate becomes a rate-determining process.

This will be described more specifically. It is assumed that there is an ideal case in which no gas remains in the vacuum vessel and the gas put in the vacuum vessel flows so as to expel the gas that has existed before. First, it is assumed that the pressure in the vacuum container is 20 Torr and a certain gas A is filled. At that time, two different types of gas B
At a flow rate of 00 sccm and a pumping speed of 0.1 l / l to maintain the pressure at 20 Torr,
The time required for the gas in the vacuum vessel to change from A to B is about 3 minutes. On the other hand, when the pressure in the vacuum vessel is 200 Torr and a certain gas A is filled, a different type of gas B flows at a flow rate of 200 sccm and the pressure is 20
When the pumping speed is set to 0.01 l / sec in order to maintain the pressure at 0 Torr, the time required for the gas in the vacuum vessel to change from A to B is about 30 minutes. That is, the latter takes ten times as long as the former.

When the above example is applied to the above-described embodiment, it is the same as the case where the partial pressure of Cu (hfac) ₂ gradually increases in a vacuum vessel which was initially an atmosphere of N ₂ and Hhfac. It is. The partial pressure of Cu (hfac) ₂ in the vacuum chamber is the same as the Cu (hfac) ₂ in the saturated vapor pressure of a time as a boundary, the sublimation process is rate-determining step at that time. In other words, when the relationship of (amount of exhausted copper complex gas) <(amount of copper complex gas generated by chemical vapor etching) holds, Cu (h
fac) ₂ , the amount of copper complex gas generated by chemical vapor etching cannot be increased beyond the amount of exhausted copper complex gas, and the sublimation rate becomes slow. It is considered that the sublimation step is rate-determining, and (amount of copper complex gas exhausted) = (amount of copper complex gas generated by chemical vapor etching). From the above,
The evacuation is performed by changing the evacuation capacity, preferably by intermittently changing the evacuation speed.

The case of the second reason will be described in detail. As the cleaning process proceeds, the gas in the vicinity of the adhered metallic copper increases the proportion of H ₂ O gas, which is a copper complex substrate or a reaction product, gradually decreases the proportion of oxygen, and decreases the oxygen partial pressure. The decrease lowers the oxidation rate of the copper thin film. Removal rate when the oxidation process is the rate-determining process,
That is, the oxidation rate R of metallic copper is R = K × [P _O2 ] ⁿ ×
[Cu] (K: reaction rate constant, [P _O2 ]: concentration of oxygen near the surface, n: multiplier (1), [Cu]: amount of Cu capable of reacting with O ₂ or surface area of Cu) expressed. As is apparent from the equation, as the oxygen partial pressure decreases, the oxidation rate of metallic copper decreases. Further, as the time elapses, the partial pressure of the copper complex gas near the surface of the adhered metallic copper increases, so that the amount of Cu that can react with O ₂ , that is, the amount proportional to the surface area of Cu, slightly decreases. As is clear from the equation, the oxidation rate of metallic copper is proportional to the surface area of Cu. Therefore, when the partial pressure of the copper complex gas near the surface of the adhered metallic copper increases, the oxidizing rate of metallic copper decreases. Therefore, when removing a copper thin film having a thickness of, for example, 10 μm or more, intermittent exhaust is performed to accelerate the oxidation process.

The adjustment of the internal pressure of the vacuum vessel 11 based on the intermittent exhaust is performed by changing the conductance of the piping of the exhaust system 14.
This is done by changing the pumping speed. For example, in Example 1 described above, N ₂ (140 sccm), β-diketone (40
When the pressure (sccm) and oxygen (20 sccm) are simultaneously introduced into the vacuum vessel 11 and the pressure inside the vacuum vessel 11 is kept at 20 Torr, the conductance is kept at about 0.1 l (liter) / sec. Similarly, N ₂ (140 sccm), β-diketone (40 sccm) and oxygen (20 sccm) are simultaneously placed in the vacuum vessel 1.
1, the conductance is maintained at about 0.01 liter / second when the pressure in the vacuum vessel 11 is maintained at 200 Torr. At this time, a dry pump is used for evacuation. Since the pumping speed of the dry pump is as large as 1000 l / sec nominally, there is no problem with respect to the conductance.

When the evacuation speed is changed to perform evacuation to a high vacuum, the conductance of the evacuation system piping is increased. The conductance in the case where the cleaning step is performed as in the first embodiment and the vacuum is exhausted in the middle of the cleaning step is about 50 l / sec. By closing the valves 23 and 25 and increasing the conductance to 50 l / sec, the inside of the vacuum vessel 11 could be reduced to 1 × 10 ⁻² Torr or less within 30 seconds.

Next, the temperature condition, the oxygen partial pressure condition, and the flow rate relationship between oxygen and β-diketone in the cleaning method of Example 1 will be described. The conditions of the temperature, the conditions of the partial pressure of oxygen, and the conditions of the flow rate relationship between oxygen and β-diketone were set as follows.

The temperature was set between 100 ° C. and 400 ° C. When the temperature is lower than 100 ° C., the oxidation step, the complexing step, and the sublimation step do not proceed at a practical speed, and
If it exceeds 0 ° C., β-diketone is oxidized and decomposed. The temperature range is preferably 190 to 3 which can achieve a removal rate of 5000 Å / sec or more.
It is in the range of 10 ° C., more preferably 210-230.
° C.

The pressure was set to a partial pressure of oxygen of 100 mTorr or more and 300 Torr or less. Oxygen partial pressure is 100mTorr
If it is smaller, the oxidation step, complexing step and sublimation step do not proceed at a practical rate, and if it is larger than 300 Torr, the oxidation step does not become a rate-determining step. The range of the oxygen partial pressure is preferably in the range of 1 to 200 Torr at which a removal rate of 5000 Å / sec or more can be set, and the most preferable oxygen partial pressure is 2 Torr.

Regarding the flow rate relationship between oxygen and β-diketone, the flow rate of oxygen in the vacuum vessel 11 is preferably not more than five times the molar flow rate of β-diketone. In particular, when a removal rate of 5000 Å / sec or more is realized, the flow rate of oxygen is １ ／ of the flow rate of β-diketone in molar ratio.
It is preferable that

[Embodiment 2] In the cleaning method of Embodiment 1 described above, β-diketone was first introduced into a vacuum vessel to create a complexable atmosphere, and then oxygen was introduced to allow oxidation. In this example, β-diketone and oxygen were simultaneously introduced into the vacuum vessel,
An atmosphere capable of being complexed and an atmosphere capable of being oxidized were simultaneously formed. Even if an atmosphere capable of being complexed and an atmosphere capable of being oxidized are simultaneously created in the vacuum vessel, the above-described cleaning conditions (the oxidation step is a rate-determining step) can be set,
Smooth cleaning of the deposited film of metallic copper could be performed.

A specific example of a film forming apparatus to which the cleaning method according to the present invention is applied will be described with reference to FIG.
This film forming apparatus is a CVD apparatus. In FIG.
Elements that are substantially the same as the elements described in FIG. 1 are denoted by the same reference numerals.

In the CVD apparatus, the vacuum vessel 11 has an exhaust system 14
And a pipe 15, a main valve 16 and a gate valve 13, and a substrate 51 is disposed on the substrate holder 12. A heater 18 is provided inside the substrate holder 12. The substrate 5 on the substrate holder 12 in the vacuum vessel 11
A gas introduction guide 52 is provided in the front space of the substrate so as to face the surface (film-forming surface) of the first substrate. The gas introduction guide 52 is provided at the end on the upper wall side of the vacuum vessel 11.
3 and a gas rectification unit 5
4 is provided. The gas introduction port 53 is located substantially at the center of the gas rectification unit 54 as viewed from the gas introduction guide 52 from the substrate 51 side, and is arranged so as to be coaxial with the center of the substrate 51. The gas rectification unit 54 faces the film formation surface of the substrate 51 and has an opening area of the gas rectification unit 54 (the area of the opening in the horizontal cross section).
Are formed so as to gradually increase as approaching the substrate 51. In the illustrated example, in the gas introduction guide 52, a portion extending downward from the gas introduction port 53 to the lower end opening is smoothly expanded like a horn of a musical instrument to form the gas rectification unit 54. I have. The gas rectifying section 54 can also have its opening area increased stepwise in a stepwise manner. Regarding the horn shape of the gas rectifying portion 54 of the gas introduction guide 52, the distance from the center to the peripheral portion gradually or stepwise decreases from the center to the peripheral portion in relation to the flow velocity of the gas flowing along the substrate surface. It can also be said that it has a shape. The configuration and operation of the gas introduction guide 52 having such a horn stream structure will be described in detail in Japanese Patent Application No. 8-231513.

A gas introduction pipe 55 is attached to the upper wall 11a of the vacuum vessel 11. The base end of the gas introduction pipe 55
Source gas supply system 3 for supplying a source gas to the surface of substrate 51
The vaporizer 31 is connected to the gas inlet port 53 via a gas inlet joint 56. When the source gas is supplied from the source gas supply system 30 to the space in front of the substrate 51 through the gas introduction pipe 55 and the gas introduction guide 52, the substrate 51 heated by the heater 18
On the surface and near the surface, a chemical reaction is induced by the source gas, and a thin film is deposited on the substrate surface.

The vacuum vessel 11 is made of, for example, stainless steel or an aluminum alloy. Vacuum container 11
Is provided with a temperature control mechanism, and the temperature control mechanism includes a heater 57, a temperature sensor 58, and the like. The temperature of the vacuum vessel 11 is maintained at about 60 ° C.

The source gas supply system 30 vaporizes the liquid source and supplies the gaseous source to the space in front of the substrate 51.
The raw material gas supply system 30 includes a raw material container 32 storing a liquid raw material, and the vaporizer 31 for vaporizing the liquid raw material carried from the raw material container 32. Further, the gas introduction pipe 55 for guiding the material vaporized by the vaporizer 31 into the vacuum vessel 11 and the gas introduction guide 52 connected to the gas introduction pipe 55 can be considered as a part of the source gas supply system 30. The raw material container 32 and the vaporizer 31 are connected by a liquid sending pipe 33, and the liquid sending pipe 33 is provided with a liquid flow controller (not shown) for adjusting the flow rate of the raw material.

The vaporizer 31 is provided with a pipe 34 for introducing a carrier gas such as a hydrogen gas, a helium gas, and a nitrogen gas. The pipe 34 is provided with a carrier gas flow rate regulator (not shown) for adjusting the flow rate of the carrier gas. The vaporizer 31 has a structure capable of mixing a source gas and a carrier gas. As described above, the gas introduction pipe 55 for introducing the vaporized raw material and the carrier gas into the vacuum vessel is connected to the vaporizer 31. Further, the vaporizer 31 is provided with a temperature control mechanism 35 for controlling the temperature thereof to a predetermined temperature, the pipe 34 is provided with a temperature control mechanism 36 for controlling the temperature thereof to a predetermined temperature, and the gas introduction pipe 33 is provided with a temperature control mechanism 36. A temperature control mechanism 37 for controlling the temperature to a predetermined temperature is provided. In the present embodiment, the temperatures of the vaporizer 31, the pipe 34, and the gas introduction pipe 37 are maintained at, for example, about 50 ° C.

The gas introduction guide 52 is provided with a guide temperature control mechanism 41 for appropriately controlling the temperature. Further, around the gas introduction guide 52, a gas introduction guide mounting mechanism 42 for supporting and fixing the gas introduction guide 52 at a predetermined position in the vacuum vessel 11 is arranged.

The guide temperature control mechanism 41 includes a heater 43 provided in contact with the back surface of the portion of the gas introduction guide 52 facing the substrate 51, and a cooling device provided in contact with the back surface for cooling the gas introduction guide. A temperature sensor 45 for detecting the temperature of the refrigerant flow passage 44, the gas introduction guide 52, and a controller for controlling the heating amount of the heater 43 and the temperature and flow rate of the refrigerant flowing through the refrigerant flow passage 44 based on a signal from the temperature sensor 45. (Not shown)).

The gas introduction guide mounting mechanism 42 is an annular plate made of, for example, alumina, and extends from the lower peripheral portion of the gas introduction guide 52 so as to be parallel to the substrate 51.
Its outer peripheral edge is attached to the inner surface of the vacuum vessel 11. The gas introduction guide mounting mechanism 42 includes a temperature control mechanism 46 for maintaining the same temperature as the vacuum vessel 11. The temperature control mechanism 46 includes a heater 47 for heating the gas introduction guide attachment mechanism 42, a refrigerant flow passage 48 for flowing a refrigerant for cooling the gas introduction guide attachment mechanism 42, and a temperature for measuring the temperature of the gas introduction guide attachment mechanism 42. Sensor 49
And a controller (not shown) for controlling the heating amount of the heater 47 and the temperature and flow rate of the refrigerant flowing through the refrigerant flow passage 48 based on the detection signal of the temperature sensor 49.

The gas introducing joint 56 attached to the gas introducing port 53 is preferably made of a resin having excellent heat resistance and low thermal conductivity, and is connected to the gas introducing pipe 52 and the vacuum vessel 11 from the gas introducing guide 52. Has the effect of suppressing the conduction of heat.

The above-described film forming apparatus 10 is further provided with the above-described oxygen supply system 21, β-diketone supply system 23, and valves 223 and 25, and further controls the cleaning method according to the present invention. A mechanism is attached.

In the film forming apparatus described above, the film is likely to adhere mainly to the surface of the gas introduction guide 52 facing the substrate. Therefore, the above-described cleaning method is performed in the vacuum vessel 11 at an appropriate timing.

[0070]

As is apparent from the above description, according to the present invention, since the cleaning conditions are set so that the oxidation step is a rate-determining step, copper oxide and the like do not accumulate and the film is formed. The film can be smoothly removed from the surface of the film attached inside the processing apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a typical configuration of a film forming apparatus to which a cleaning method according to the present invention is applied.

FIG. 2 is a longitudinal sectional view showing a specific example of the inside of a film forming apparatus.

FIG. 3 is a photograph showing a first example of a sponge-like thin film.

FIG. 4 is a photograph showing an enlarged cross section of a sponge-like thin film.

FIG. 5 is a photograph showing the appearance of a cracked thin film.

FIG. 6 is a photograph showing an enlarged cross section of an inner state of a cracked thin film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Film-forming processing apparatus 11 Vacuum container 12 Substrate holder 13 Gate valve 14 Exhaust system 16 Main valve 17, 18 Heater 19 Adhesion film 23, 25 Valve

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/3065 H01L 21/205 // H01L 21/205 21/302 N (72) Inventor Atsushi Sekiguchi 5-chome, Yotsuya, Fuchu-shi, Tokyo No. 8 inside Anelva Co., Ltd. (72) Inventor Osamu Okada 5-1-1 Yotsuya, Fuchu-shi, Tokyo Inside Anelva Co., Ltd.

Claims (13)

[Claims] 1. A film forming apparatus for depositing a metal film on a surface of a substrate, wherein the metal film attached to the inside of the film forming apparatus at the time of film formation is oxidized to form an oxide film of the metal film. A cleaning method for removing by a cleaning process including an oxidation process, a complexing process of complexing the oxide film to form a complex thereof, and a sublimation process of sublimating the complex, wherein the oxidation process is a rate-determining process. Wherein the conditions of the cleaning step are set in the film forming apparatus. 2. A film forming apparatus for depositing metallic copper on a surface of a substrate, wherein said metallic copper adhered inside said film forming apparatus during film formation is oxidized to form copper oxide by oxidizing said metallic copper. And a complexing step of complexing the copper oxide to form a copper complex,
A film forming apparatus, comprising: a cleaning method for removing a copper complex by a sublimation step of sublimating the copper complex; wherein a condition of the cleaning step is set so that the oxidation step is a rate-determining step. Cleaning method for the metal film attached inside. 3. The method according to claim 1, wherein the conditions of the cleaning step in which the oxidation step is a rate-determining step are set by creating an atmosphere capable of being complexed and then creating an atmosphere capable of being oxidized. 3. A method for cleaning an adhered metal film in a film forming apparatus according to item 2. 4. The cleaning step in which the oxidizing step is a rate-determining step is set by simultaneously creating a complexable atmosphere and an oxidizable atmosphere. Cleaning method for the deposited metal film in the film forming apparatus. 5. The method according to claim 2, wherein the copper complex is a β-diketone complex formed using β-diketone. 6. The cleaning of the deposited metal film in the film forming apparatus according to claim 3, wherein the oxidizable atmosphere is created by introducing oxygen into the film forming apparatus. Method. 7. The deposited metal in a film forming apparatus according to claim 3, wherein the complexable atmosphere is created by introducing β-diketone into the film forming apparatus. How to clean the membrane. 8. The method for cleaning a deposited metal film in a film forming apparatus according to claim 5, wherein hexafluoroacetylacetone is used as β-diketone. 9. The method according to claim 1, wherein the reaction in the oxidation step does not proceed more than the reaction in the complexing step.
3. A method for cleaning an adhered metal film in a film forming apparatus according to item 2. 10. The method for cleaning a deposited metal film in a film forming apparatus according to claim 1, wherein an exhaust speed is intermittently changed during the cleaning step. 11. The film forming apparatus is a CVD film forming apparatus having a gas introduction guide having a horn stream structure in a space in front of the substrate, and the metal copper to be removed is mainly a substrate of the gas introduction guide. 3. The method for cleaning an adhered metal film in a film-forming apparatus according to claim 2, wherein the adhered metal is copper metal. 12. An oxidizable atmosphere in the oxidizing step is made of oxygen, and an oxidizable atmosphere in the complexing step is β-
When made with diketone, at the time of the cleaning process,
12. The apparatus according to claim 1, wherein the temperature in the film forming apparatus is a temperature included in a range of 100 to 400 [deg.] C., and the pressure in the film forming apparatus is 100 mTorr to 300 Torr in oxygen partial pressure. The method for cleaning an adhered metal film in a film forming apparatus according to any one of the preceding claims. 13. An oxidizable atmosphere in the oxidizing step is made of oxygen, and an oxidizable atmosphere in the complexing step is β-
12. When made of diketone, the flow rate of the oxygen is 5 times or less in molar ratio of the flow rate of the β-diketone in the film forming apparatus.
13. The method for cleaning a deposited metal film in a film forming apparatus according to any one of the above items.