WO2007069599A1

WO2007069599A1 - Method for precoating film forming apparatus

Info

Publication number: WO2007069599A1
Application number: PCT/JP2006/324749
Authority: WO
Inventors: Takaya Shimizu; Shinya Okabe; Kunihiro Tada
Original assignee: Tokyo Electron Limited
Priority date: 2005-12-12
Filing date: 2006-12-12
Publication date: 2007-06-21
Also published as: JP2007165479A; TW200738902A

Abstract

This invention provides a method for precoating the inside of a vacuum treatment vessel for receiving therein an object to be treated in a plasma CVD film forming apparatus. This method is characterized by supplying a treatment gas into a treatment vessel in which any object to be treated has not been received, to form a precoating film (82) having a thickness X falling within a thickness range represented by the following formula: C ≤ X ≤ A - B wherein A represents the maximum film thickness which is the unseparable maximum thickness of films (82, 84) deposited on a surface (34) of a shower head within the treatment vessel by plasma CVD using the treatment gas; B represents the cumulated total film thickness obtained by cumulating the thickness of films deposited on the surface of a plurality of objects by film formation treatment in a cleaning period; and C represents the radiation saturated film thickness which is the thickness of the precoating film which causes substantial saturation of emissivity of the precoating film (82).

Description

Specification

Pre-coating method for film forming apparatus

Technical field

[0001] The present invention relates to a method for pre-coating in a vacuum processing container of a film forming apparatus for depositing a thin film by plasma CVD on the surface of an object to be processed such as a semiconductor wafer.

Background art

[0002] Generally, in order to manufacture a semiconductor integrated circuit, various processes such as a film formation process, an etching process, an oxidation diffusion process, an annealing process, and a modification process are repeatedly performed on a substrate such as a semiconductor wafer. Thus, a large number of desired elements are formed. Taking film formation as an example, the film thickness to be formed must be uniform within the wafer surface. Is required to be good.

[0003] By the way, for example, in a single-wafer type film forming apparatus, a cleaning process is performed by flowing a tung gas (etching gas) into a processing container every predetermined period. As a result, an unnecessary adhesion film adhering to the surface of the shower head that supplies gas into the processing container, the surface of the mounting table on which the wafer is placed, the inner wall surface of the processing container, or the surface of other internal structure of the container is removed. Remove.

[0004] Immediately after such a cleaning process is performed, thermal effects such as the emissivity of each structure in the processing container are not stable. In view of this, the so-called pre-coating film forming process is performed in a state in which the product wafer is not carried into the processing container immediately without processing the product wafer (Japanese Patent Laid-Open Nos. 2000-277459 and 2002). — No. 167673, JP 2004-285469). In this film formation process of the precoat film, the same gas as that used for film formation of the wafer is flowed into the processing container to deposit the film on the surface of the structure in the container with a certain thickness.

[0005] The precoat process for forming the precoat film generally requires a processing time corresponding to the time required for processing a large number of product wafers. The thicker the precoat film, the better the thermal stability and the better the film thickness reproducibility on the product wafer. There Therefore, a pre-film having a certain thickness is formed as soon as possible by flowing a film-forming gas at a higher flow rate than in the film-forming process of the product wafer. As a result, the pre-coating process is completed in a short time, and the product wafer film forming process is immediately started to improve productivity.

Disclosure of the invention

By the way, in the conventional precoat method as described above, the precoat process can be completed in a short time. However, as a result of flowing a larger amount of film deposition gas during pre-coating than during film deposition of the product wafer, the pre-coating film tends to adhere to the periphery of the surface of the shower head more thickly than other parts. . As a result, there is a problem that when the process moves to the film forming process of the product wafer, the adhered film around the shower head is easily peeled off relatively quickly, and particles that cause product defects are generated. I

[0007] This point will be described with reference to FIG. FIG. 12 is a diagram showing the film thickness distribution of the precoat film 4 adhered to the shower head 2 when a bricote film is formed by flowing a large amount of film forming gas. As shown in the figure, the precoat film 4 adhered to the lower surface of the shower head 2 has a film thickness distribution in which the peripheral thickness H2 is considerably thicker than the central thickness HI. . FIG. 12 shows the distribution of particles on the surface of the last processed wafer W (dots in the figure) when a predetermined number of product wafers W are continuously formed. It is shown. As shown in the figure, many particles are distributed around the periphery of the wafer W. This is thought to be because the deposited film adhering to the periphery of the shower head 2 peels off quickly and turns into particles.

[0008] The present invention has been devised to pay attention to the above problems and to effectively solve them. An object of the present invention is to provide a pre-coating method for a film forming apparatus that can suppress generation of particles by peeling off an unnecessary attached film attached to a shower head during film forming processing.

[0009] To achieve this object, the present invention provides:

A method of applying a precoat in a vacuum processing container of a film forming apparatus,

The processing container is provided with a shower head for supplying a processing gas including a film forming gas. And

The film forming apparatus is configured to supply the processing gas into the processing container containing the target object and deposit a thin film on the surface of the target object by plasma CVD. Hurry up in the way!

A pre-coating film having a thickness X within a range represented by the following formula is formed by plasma CVD by supplying the processing gas into the processing container and storing the object to be processed. Provide a pre-coating method with:

C≤X≤A— B

A is a maximum film thickness that is the maximum film thickness of the shower head adhesion film that adheres to the surface of the shower head by plasma CVD using the processing gas without peeling off the surface force of the shower head;

B is an integrated total film thickness obtained by integrating the thicknesses of films deposited on the surfaces of a plurality of objects to be processed by the film forming process during the cleaning cycle;

C is a radiation saturation film thickness that is a film thickness of the precoat film such that the emissivity of the precoat film is substantially saturated.

The present invention also provides

The processing container is provided with a shower head for supplying a processing gas including a film forming gas,

C≤X≤D

C is a radiation saturation film thickness that is the film thickness of the precoat film such that the emissivity of the precoat film is substantially saturated; D is the film thickness of the precoat film in which the phenomenon that the number of generated particles begins to increase suddenly when a predetermined number of semiconductor wafers are formed while gradually increasing the film thickness of the precoat film. Critical film thickness.

[0011] In the latter method, for example, the thin film is a Ti-containing film, the radiation saturation film thickness (C) is 500 nm, and the critical film thickness (D) is 720 nm. For example, the thin film is formed by depositing a Ti film on the surface of the object to be processed and then nitriding at least the surface of the Ti film.

[0012] According to these pre-coating methods, the film forming process is performed while ensuring the minimum film thickness of the pre-coating film without substantially changing the width emissivity even when the film forming process on the object to be processed is started. Occasionally, unnecessary adhesion film adhering to the share head is prevented from peeling off and particles can be prevented from being generated. Thereby, the uniformity of the film thickness of the thin film formed in a to-be-processed object can be made high, suppressing generation | occurrence | production of the particle in a processing container. Therefore, the reproducibility of the film thickness can be improved.

[0013] The precoat film is preferably formed by sequentially laminating a plurality of precoat layers.

[0014] Thereby, it is possible to make the film thickness of the precoat film particularly uniform on the surface of the shower head. As a result, it is possible to carry out a film forming process for a larger number of objects to be processed before an unnecessary adhering film adhering to the shower head is peeled off and a partition is generated, that is, the cleaning cycle can be lengthened. Productivity can be improved.

[0015] When forming a precoat film by sequentially laminating a plurality of precoat layers, each precoat layer has the same flow rate as the flow rate of the film forming gas supplied when depositing a thin film on the surface of the object to be processed. Preferably, the film forming gas is supplied to form the film. Thereby, the in-plane uniformity of the precoat film thickness can be further improved.

The present invention also provides a storage medium storing a program for controlling the film forming apparatus so as to execute the above-described precoat method. Brief Description of Drawings

[0017] FIG. 1 is a schematic diagram showing an example of a film forming apparatus to which the precoat method of the present invention is applied;

[FIG. 2] is a film including a precoat film on the surface of the shower head and the mounting table in the apparatus of FIG. The figure which shows the state which accumulated

[Figure 3] is a graph showing the relationship between the precoat film thickness and the reproducibility of the film thickness formed on the wafer surface;

[Fig. 4A] is a graph showing the relationship between the thickness of TiN film and transmittance;

[Figure 4B] is a graph showing the relationship between TiN film thickness and reflectance;

[Figure 5] is a graph showing the relationship between the precoat film thickness and the number of particles generated during the film formation process;

[Figure 6] is a graph to explain the optimum range of precoat film thickness;

[FIG. 7A] is a schematic diagram for explaining generation of particles in a conventional pre-coating method;

FIG. 7B is a schematic diagram for explaining suppression of particle generation in the precoat method of the present invention;

[FIG. 7C] is a table showing the process conditions and the precoat film thickness data obtained for the conventional method and the method of the present invention;

[Fig. 8] is a graph showing a comparison of changes in the number of particles generated between the conventional pre-coating method and the pre-coating method of the present invention;

[Fig. 9] is a graph comparing the thickness of the precoat film formed on the surface between the mounting table and the shower head;

[Fig. 10] is a graph showing the film thickness distribution of the precoat film deposited on the wafer surface by the conventional precoat method;

FIG. 11 is a graph showing the film thickness distribution of the precoat film adhered to the wafer surface by the precoat method of the present invention;

FIG. 12 is a diagram showing the film thickness distribution of the precoat film adhering to the showerhead surface and the particle distribution on the surface of the semiconductor wafer.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of a pre-coating method for a film forming apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

In the present embodiment, the film forming apparatus shown in FIG. (Tan) film and TiN (titanium nitride) film will be described as an example.

A film forming apparatus 12 shown in FIG. 1 has a processing container 14 formed in a cylindrical shape, and the processing container 14 is grounded. An exhaust port 18 is provided at the bottom 16 of the processing vessel 14 for discharging the atmosphere in the vessel. The exhaust port 18 is provided with an exhaust system having a pressure adjusting valve 20 and a vacuum pump 22 interposed therebetween. 24 is connected so that the inside of the processing vessel 14 can be uniformly evacuated from the bottom peripheral portion.

[0021] The processing vessel 14 is welded to a hollow support 26 made of aluminum nitride (A1N), and is provided with a disk-like mounting table 28 made of A1N. Ueno and W can be placed. The mounting table 28 is embedded with a lower electrode 29 having a mesh-like metal material force and a resistance heater 30 as a heating means. The lower electrode 29 is grounded, and the mounting table 28 is heated to a predetermined temperature by supplying power to the resistance heater 30 from a power supply (not shown).

[0022] A ceiling plate 34 provided with a shower head 32 as a gas supply means also serving as an upper electrode is provided on the ceiling of the processing vessel 14 through an insulating material 36 with respect to the side wall of the vessel. Closely attached. The shower head 32 is provided so as to face almost the entire upper surface of the mounting table 28, and a processing space S is formed between the shower head 32 and the mounting table 28. This shower head 32 introduces various gases into the processing space S in a shower form, and a plurality of injection holes 39 for injecting gas are formed on the injection surface 37 on the lower surface of the shower head 32. In addition, a diffusion plate 40 having a large number of diffusion holes 38 is provided inside the shower head 32 so that gas can be diffused.

[0023] A gas introduction port 42 for introducing gas into the head is provided above the shower head 32, and a plurality of, for example, two supply gas flows through the gas introduction port 42. Passages 44 and 46 are connected.

[0024] A plurality of branch pipes 48 are connected to one supply passage 44, and each branch pipe 48 is supplied with a film forming gas, for example, a TiCl gas source 50 for storing TiCl gas, and H gas as a reducing gas. Storage

4 4 2 H gas source 52, Ar gas source 54 for storing, for example, Ar gas as plasma excitation gas,

2

C1F-based gas, for example C1F gas, is stored as the cleaning gas used for cleaning

3 C1F gas sources 56 are connected. The other supply passage 46 has NH An NH gas source 58 for storing gas is connected. Although not shown, if necessary, N2

Three

A gas supply system for supplying gas is also connected. The distribution and flow rate of each gas are controlled by an on-off valve 60 and a flow rate controller such as a mass flow controller 62 provided in each branch pipe 48 and supply passage 44, respectively.

[0025] Further, in order to form plasma when Ti film is formed and when the Ti film is nitrided, a matching circuit 66 and a high frequency for plasma of 13.56 MHz, for example, are formed on the ceiling plate 34 via a lead wire 64. Power supply 68 is connected. Further, in order to adjust the temperature of the wall surface, a resistance heater 70 is inserted into the side wall of the processing vessel 14 as necessary, and the resistance heater 70 is connected to a temperature controller (not shown). On the side wall of the container, there is provided a gate valve 74 that can be opened and closed airtightly when the wafer is loaded into and unloaded from the load lock chamber 72. Further, the shower head 32 is also provided with a resistance heater 76 for temperature adjustment, and the resistance heater 76 is connected to a temperature controller (not shown).

[0026] The operation of the entire apparatus is controlled by a control unit 78 including, for example, a microcomputer. The control unit 78 includes a storage medium 80 that stores a program for performing a series of operations such as a pre-coating process and a film forming process described later. As the storage medium 80, for example, a flexible disk, a CD-ROM, a DVD, a hard disk, or the like can be used.

Next, a film forming method performed based on the apparatus configured as described above will be described with reference to FIG. FIG. 2 is a view schematically showing a state in which a thin film (precoat film) is deposited on the ejection surface 37 and the mounting table 28 which are the lower surfaces of the shower head 32.

[0028] As described above, every time a predetermined number of wafers are processed, or every predetermined period such as every time the total total film thickness on the wafer reaches a predetermined amount, the non-adhering material adhered to the surface of the internal structure of the container. A cleaning process for removing the necessary adhered film is performed. After this cleaning process is performed, pre-coating is performed to stabilize the radiation rate in the processing vessel that causes film thickness fluctuations, especially radiation from the shower head and mounting table, before actually depositing the film on the semiconductor wafer. Process.

In the method of the present invention, a precoat film is formed by forming a film on the surface of the in-container structure such as the surface of the shower head 32 and the surface of the mounting table 28 using the same kind of gas as that used when forming the wafer. . In this case, it is intended to form a Ti film and a TiN film on the wafer as a thin film. Therefore, a thin film containing Ti metal, such as a Ti film or a TiN film, is formed as the precoat film. Here, the case where the TiN film is formed by nitriding the surface or the whole of the Ti film will be described as an example. The operation described below is performed based on the program stored in the storage medium 80.

[0030] <Precoat treatment>

First, without introducing the semiconductor wafer W into the processing container 14, for example, the load is kept in the load lock chamber 72. In this state, no film is formed on the ejection surface 37 of the shower head 32 or the surface of the mounting table 28 immediately after cleaning.

Thus, in a state where nothing is placed on the placing table 28, as a processing gas, for example, TiCl gas as a film forming gas, Ar gas as a gas for plasma excitation, for example, H gas or the like is used.

4 2

Then, the liquid is introduced into the processing container 14 from the shower head 32 at a predetermined flow rate. On the other hand, the inside of the processing container 14 is evacuated by the vacuum pump 22 and maintained at a predetermined pressure.

At the same time, a 450 kHz high frequency is applied from the high frequency power supply 68 to the shower head 32 as the upper electrode, and a high frequency electric field is applied between the shower head 32 and the lower electrode 29. As a result, Ar gas is turned into plasma, and the reduction reaction between TiCl gas and H gas is promoted.

4 2

A Ti film is formed so as to cover the entire surface including the ejection surface 37 of the keyer head 32 and the upper surface of the mounting table 28. This Ti film is set to have a thickness of about 20 nm (deposition time is about 60 sec), for example.

At this time, the temperature of the mounting table 28 is heated by the resistance heater 30 embedded in the mounting table 28 to the same temperature as the film forming process on the Weno and W. The shower head 32 is heated to a predetermined temperature by a resistance heating heater 76. Normally, the temperature of the shower head 32 is set to a temperature of 400 ° C. or higher at which the Ti film or TiN film formed on the surface of the shower head is stabilized.

As for the process conditions at this time, in the case of a 300 mm wafer processing apparatus, the mounting table temperature is, for example, about 600 ° C., the process pressure is about 666.7 Pa, and the high-frequency power is about 800 to 1000 W. The gas flow rate is, for example, about 12 sccm for TiCl gas, H gas power OOOscc

4 2

m, Ar gas is about 1600sccm.

[0033] Once the Ti film is formed in this way, the processing vessel 14 is evacuated to eliminate residual gas. Then, the next nitriding process is started.

In this nitriding treatment, the flow rates of the nitriding gases NH, H and Ar are each controlled.

3 2

The Ti film is nitrided by forming a TiN film by supplying it under control and generating plasma by high frequency to activate each gas. At this time, only the surface of the Ti film is nitrided to form a TiN film, and the entire Ti film is nitrided to form a TiN film.

The process conditions at this time are, for example, a mounting table temperature of about 600 ° C., a process pressure of about 666.7 Pa, and a high-frequency power of about 800 W. The gas flow rate is 1500scc for NH gas.

Three

m, H gas is about 2000 sccm, Ar gas is about 1600 sccm, and the nitriding time is 6

2

About Osec.

[0034] Thereby, one precoat layer is formed. Here, the process conditions of the Ti film formation process and Ti film nitridation process, that is, various gas flow rates, film thicknesses, and the like are substantially the same as those of the Ti film formation process and nitridation process performed on one product wafer. Set the same. Thereby, as will be described later, the film thickness of the precoat layer can be made more uniform in the plane. When a single precoat layer is thus formed, the Ti film formation process and the Ti film nitridation process are repeated a predetermined number of times, for example, 33 to 40 times (cycles) in succession. Are laminated in multiple layers. As a result, as shown in FIG. 2, a precoat film 82 having a total thickness X is formed on the ejection surface 37 of the shower head 32, the upper surface of the mounting table 28, and the like.

In this case, although not shown, a precoat film is also formed on the upper surface side of the mounting table 28 facing each other across the processing space S in a state substantially similar to the above. In FIG. 2, the force is described so that the thickness X of the precoat film 82 is uniform. Actually, the thickness X has a distribution that varies in-plane due to process conditions and the like. Become.

In addition, since there is little gas wraparound to the back surface side (lower surface side) of the mounting table 28, the thickness of the precoat film in this portion is smaller than “X”.

[0036] <Film Forming Process on Wafer>

If the formation of the precoat 82 is completed as described above, the process then proceeds to the actual film forming operation on the surface of the product wafer.

First, the load lock chamber 72 force is applied through the gate valve 74 (see Fig. 1) with the wafer W opened. Then, it is loaded into the processing container 14 and placed on the mounting table 28. Then, the film forming process for the wafer W is started in a state where the inside of the processing container 14 is airtight.

First, here, a Ti film is formed on the wafer surface. For example, as described above, the Ti film is formed with the same film formation gas and gas flow rate as those used in the previous precoat film 82 formation. That is, TiCl gas as the film forming gas, H gas as the reducing gas, and Ar as the plasma excitation gas.

4 2

A gas is introduced into the processing container 14 at a predetermined flow rate, and the processing container 4 is maintained at a predetermined pressure by evacuation. Then, a Ti film with a predetermined thickness is formed on the wafer surface by a plasma-assisted reduction reaction.

With respect to the process conditions at this time, as described above, in the case of film formation on a 300 mm wafer, the gas flow rate is the same as that during the film formation of the precoat film. Specifically, the temperature of the mounting table is about 600 ° C, the process pressure is about 666.7 Pa, and the high-frequency power is about 500 W. The gas flow rate is about 12 sccm for TiCl gas, H gas power OOOsccm, for example.

4 2

The Ar gas is about 1600sccm. The film formation time is, for example, about 30 seconds, thereby forming a Ti film having a thickness of about lOnm.

[0038] Once the Ti film is formed in this way, the inside of the processing container 14 is evacuated to remove the residual gas, and the next nitriding process is started. In this nitriding treatment, the nitriding gas NH and H gas

3 2

Then, Ar gas is supplied while controlling the flow rate, and plasma is generated by high frequency to activate each gas, thereby nitriding the Ti film and forming a TiN film on the surface. Regarding the process conditions at this time, the gas flow rate is the same as that of the previous precoat film formation. Specifically, the film formation temperature is, for example, about 600 ° C, the process pressure is about 666.7 Pa, and the high frequency power is about 800 W. The gas flow rate is about 1500sccm for NH gas and H gas.

3 2 is about 2000 sccm, Ar gas is about 1600 sccm, and the nitriding time is about 60 sec. In this way, the product wafer deposition process is completed.

[0039] In this way, when the film formation process for one product wafer is completed, the product wafer for which the film formation process has been completed and a new unprocessed product wafer are replaced, and the series of film formation described above is performed. Processing is performed continuously. Then, film formation processing of a certain number of wafers (for example, about 25 to 500 wafers depending on the film thickness to be formed on one wafer) is continuously performed. During that time, an unnecessary film adheres to the inside of the processing vessel 14 and internal structures, so a certain number of sheets When the wafer film forming process is completed, the container is cleaned as described above. In FIG. 2, as a result of continuously performing the film forming process on a plurality of product wafers, a film deposited cumulatively is shown as an unnecessary adhesion film 84. In addition, the cumulative total film thickness of the unnecessary adhesion film 84 immediately before the cleaning is indicated by “Β ′”.

[0040] In this cleaning process, a C1F gas such as C1F gas is used as the cleaning gas.

3 This is performed by maintaining the mounting table 28, the shower head 32, the side wall of the container, etc. at a certain temperature while flowing into the processing container 14, and evaporating and removing unnecessary films adhering to the inside. Further, when forming one precoat layer of the above-mentioned precoat film 82, the force of forming a Ti film and nitriding the surface or the whole of this Ti film to form a TiN film is not limited to this. This manufacturing method is not particularly important, even if a TiN film is deposited on the underlying Ti film by plasma CVD or thermal CVD.

[0041] <Precoat film thickness>

Next, the thickness X of the precoat film 82 to be formed will be described. The thickness X of the precoat film 82 in FIG. 2 to be formed is set within the range represented by the following equation.

C≤X≤A— B

Here, “A” is a film (precoat film 32 and unnecessary adhesion film 8) that adheres to the surface (jetting surface 37) of the discharge head 32 by plasma CVD using the above-described processing gas including a film forming gas.

4 is a maximum film thickness that is the maximum film thickness that does not peel from the surface (jetting surface 37) of the shower head 32. “B” indicates the thickness of the film deposited on the surfaces of a plurality of semiconductor wafers W by the film forming process during the cleaning cycle (within a period of time until the next cleaning is executed). The integrated total film thickness. This accumulated total film thickness B is usually substantially the same as the accumulated total film thickness of the unnecessary adhesion film 84 described above. “C” is a radiation saturation film thickness that is the film thickness of the precoat film 82 such that the emissivity of the precoat film 82 is substantially saturated.

In FIG. 2, the radiation saturation film thickness C is shown so that the precoat film 82 on the surface of the shower head 32 and the precoat film on the mounting table 28 have substantially the same film thickness. This is because, as described above, the precoat film 82 is deposited on the lower surface of the shower head 32 and the upper surface of the mounting table 28 with substantially the same thickness. This point will be described in detail later. [0043] The reason why the precoat film 82 is formed to such a thickness that the radiation from the mounting table 28 and the shower head 32 is stabilized as described above is as follows. First, if the film forming process is started on a product wafer while the emissivity in the processing container 14 is not stable, an unnecessary adhesion film is deposited and the emissivity fluctuates every time one wafer is formed. . As a result, the wafer temperature fluctuates slightly each time the product wafer is deposited, and this change in temperature causes a change in the film thickness on the wafer surface, thereby degrading the reproducibility of the film thickness. Therefore, by forming the precoat film 82 with a thickness equal to or greater than the radiation saturation film thickness C, the radiation from the mounting table 28 and the shower head 32 does not fluctuate even if the film formation process on the wafer is continued. can do.

[0044] Further, many causes of the generation of particles are that the film adhering from the ejection surface 37 of the shower head 32, which tends to deposit the largest amount of film, is peeled off during film formation. Therefore, the maximum film thickness A, which is the maximum film thickness of the shutter head adhesion film including the precoat film 32 adhering to the ejection surface 37 and the unnecessary adhesion film 84, is peeled off from the ejection surface ₃₇ . . Therefore, if the shower head adhering films 32 and 84 are thicker than the maximum film thickness A, the particles increase rapidly. The total accumulated film thickness B is a value obtained by integrating and totaling the film thicknesses of each product wafer W. When this value reaches a predetermined value, tallying is performed.

[0045] The precoat film 8 2 deposited on the ejection surface 37 of the shower head 32 (the upper surface of the mounting table 28 is the same) generally has a film thickness distribution that varies depending on the location in the surface. (In the case of the conventional pre-coating method shown in FIG. 12, the film thickness distribution varies particularly greatly). In that case, the precoat film 82 may be formed so that the film thickness X of the precoat film 82 is in the range of the above-described formula (C≤X≤AB) at any part of the ejection surface 37.

[0046] Here, the maximum film thickness A of the showerhead adhesion film will be described more specifically. This maximum film thickness A depends on the adhesion between the showerhead surface and the precoat film, and this adhesion depends on the material of the showerhead 32, the temperature, the film type of the precoat film 82, and the process conditions.

[0047] Generally, thermal CVD does not form a film at low temperatures. In the case of plasma CVD, if the temperature is too low, the film becomes very fragile and immediately peels off to become particles. Therefore, When the precoat film is formed and the film is formed on the wafer, the temperature of the shower head 32 needs to be set to a predetermined temperature or higher to strengthen the film attached to the shower head 32. This temperature depends on the deposition gas. For example, Ti deposition using TiCl gas as the deposition gas as in this embodiment.

Four

In this case, it is necessary to keep the temperature of the shower head 32 at 400 ° C or higher.

[0048] Further, in the case of a halogen-based gas such as TiCl gas, the higher the temperature of the shower head 32, the more

Four

Adhesion with the recoat film 82 is enhanced. However, when the temperature of the shower head 32 increases, corrosion of the shower head surface by halogen accelerates Z etching, so the temperature cannot be increased too much. The material of the shower head 32 of this embodiment is Ni, which is highly corrosion resistant and metal. However, since it is etched into a halogen-based gas at a temperature of 500 ° C. or higher, the upper limit of the temperature of the shower head 32 is 500 °. Set to C.

[0049] The adhesion of the precoat film is affected by the stress of the precoat film, and the higher the film stress, the easier it is to peel off. For this reason, it is necessary to reduce the film stress particularly near the boundary between the showerhead surface and the precoat film. Since the general film stress is greater in the TiN film than in the Ti film, it is preferable that the first layer of the precoat film is formed under the process conditions in which only the surface of the Ti film is nitrided after the Ti film is formed. The Ti film is an extremely active metal and is immediately oxidized or etched into TiCl gas, which is the film forming gas. For this reason, the surface of the Ti film is nitrided

Four

It is necessary to form a TiN film as a protective film.

[0050] <Modification>

Next, a modification of the above-described precoat method will be described with reference to FIGS. Here, except for the standard for determining the film thickness range of the precoat film, that is, the film formation process for the precoat film and the film formation process for the product wafer are all the same as described.

[0051] Specifically, the film thickness X of the precoat film 82 is set within the range represented by the following equation.

C≤X≤D

Here, “” is the radiation saturation film thickness at which the emissivity of the precoat film 82 is substantially saturated, as described above. In addition, “D” indicates that the precoat film 82 has a phenomenon in which the number of generated particles begins to increase suddenly when a predetermined number of semiconductor wafers are formed while the film thickness of the precoat film 82 is gradually increased. It is a critical film thickness. here In the following, a case where 25 product wafers are formed is described.

First, as shown in FIG. 3, the film thickness of the precoat film 82 formed on the shower head 32 (including the mounting table 28) and the film formed on the wafer surface when 25 wafers are formed. The relationship with thickness reproducibility (thickness variation rate) was examined. The precoat film thickness is changed within the range of 400 to 1400 nm. As is clear from FIG. 3, the reproducibility of the wafer thickness is about 4.2% when the film thickness is 400 nm, and the reproducibility of the film thickness is improved to about 1.8% when the film thickness is 1400 nm. is doing. Therefore, the reproducibility of the film thickness tends to improve as the precoat film thickness increases. Therefore, it was confirmed that the lower limit of the precoat film thickness was necessary to ensure the reproducibility of the film thickness above a certain value.

When the film is formed on the wafer at a predetermined temperature, radiation of any partial force in the processing container 14 that affects only the set temperature of the mounting table 28 affects the temperature of the wafer. In particular, the influence of radiation from the surface of the peripheral portion of the wafer mounting range of the mounting table 28 and the surface of the single head 32 positioned immediately above the mounted wafer is large. The radiation of the heated surface force depends on the emissivity of the film deposited on the surface, and this emissivity changes with the film thickness. For this reason, in order to stabilize the temperature of the UE and W and start film formation, it is necessary to set the precoat film thickness to be formed in the processing container 14 by the precoat process to a predetermined lower limit value or more. .

Therefore, as shown in FIGS. 4A and 4B, the relationship between the thickness of the precoat film made of TiN, the transmittance, and the reflectance was measured. Here, the precoat film thickness is varied from Onm to a maximum of about 6 OOnm. Even if the TiN film is formed directly or formed by nitriding the Ti film, the optical characteristics such as transmittance and reflectance will not change.

First, as shown in FIG. 4A, the transmittance of the precoat film gradually decreases as the film thickness increases, and the transmittance becomes substantially zero at a film thickness of 200 nm.

On the other hand, as shown in FIG. 4B, the reflectance gradually increases as the precoat film thickness increases, and is substantially saturated at about 40%. When the emissivity is calculated from the measurement results of Fig. 4A and Fig. 4B and the relationship of "transmittance + reflectivity + emissivity = 1", the emissivity is a force that changes from zero to 500 nm in bricote thickness. Above this, the force S can be kept constant.

Next, as shown in FIG. 5, the number of particles generated when 25 wafers were processed and the brico The relationship with the film thickness was examined. Here, the precoat film thickness is changed in the range of about 200 to 750 nm. As shown in Fig. 5, the number of particles was almost zero until the precoat film thickness was around 600 nm. The number of particles gradually increased when the precoat film thickness exceeded 600 nm. It was confirmed that the number of particles rapidly increased when the precoat film thickness exceeded the range of about 700 to 720 nm, and that the number of particles exceeded 100 when the film thickness was larger than 720 nm.

[0057] When the results shown in FIG. 4 and the results shown in FIG. 5 are combined, as shown in FIG. 6, it is preferable to set the precoat thickness of the TiN film within the range of 500 to 720 nm. Reproducibility of film thickness is 3% or less 560ηπ! It is clear that it is optimal to set within the range of ~ 700nm.

[0058] If the precoat film thickness is set so as to be within such an optimal range, the minimum film thickness of the precoat film 82 in which the emissivity does not substantially vary even when the film formation process on the wafer W is started. While ensuring, it is possible to suppress the generation of particles by peeling off an unnecessary attached film attached to the shower head 32 during the film forming process. As a result, the reproducibility of the film thickness of the thin film formed on Ueno and W can be improved while suppressing the generation of particles in the processing container 14.

[0059] Further, in the method of the present invention, the flow rate of the deposition gas (TiCl gas) at the time of forming the precoat film 82 is reduced.

Four

The flow rate is set to be the same as the flow rate at the time of film formation of the product wafer. As a result, compared with the conventional pre-coating method in which a large amount of TiCl gas was supplied to increase the deposition rate of the pre-coating film.

Four

In comparison, the in-plane uniformity of the film thickness of the formed precoat film 82 can be improved. Further, if the in-plane uniformity of the film thickness of the precoat film 82 itself is increased, that is, if the film thickness distribution is suppressed, the integrated total film thickness B until it deviates from the above equation (C≤X≤A—B) is obtained. Can be enlarged. Therefore, the cleaning cycle can be lengthened and more product wafers can be formed during that period.

FIG. 7A and FIG. 7B are schematic diagrams for explaining the presence or absence of particles in the conventional precoat method and the precoat method of the present invention.

Here, a precoat film 82 composed of a multi-layer precoat layer is formed on the spray surface of the lower surface of the shower head 32, and an unnecessary attachment attached during the film forming process of the product wafer. The deposited film 84 is deposited. In the conventional pre-coating method shown in FIG. 7A, a large amount of TiCl gas, which is a film forming gas, is supplied, so that the film thickness of the pre-coating film 82 around the shower head 32 is reduced.

Four

It is thicker than the center side (see Figure 12). As a result, even if the unnecessary adhesion film 84 is deposited with a uniform thickness during the film forming process of the product wafer, the shower head adhesion film is peeled off over the maximum film thickness A at an early stage. It has occurred.

[0061] On the other hand, according to the precoat method of the present invention shown in FIG. 7B, the flow rate of TiCl gas when forming the precoat film 82 is set lower than that in the conventional method, and is the same as when forming a product wafer.

Four

The flow rate. For this reason, the precoat film 82 is formed with high in-plane uniformity of film thickness. To this precoat film 82, an unnecessary adhesion film 84 is deposited with a uniform thickness during the film forming process of the product wafer, and the film thickness of the showerhead adhesion film does not exceed the maximum film thickness A as a whole. As a result, the generation of particles can be suppressed.

In addition, if the TiCl gas flow rate is reduced, the deposition rate of the precoat film decreases,

Four

By increasing the high-frequency power input to the container and compensating for this decrease, the decrease in productivity can be suppressed.

FIG. 7C shows an example of the process conditions at this time and the thickness of the obtained precoat film. As is clear from FIG. 7C force, the difference between the maximum value and the minimum value of the precoat film thickness was 105 nm in the case of the conventional method. On the other hand, in the case of the method of the present invention, the difference is only 25 nm, indicating that the in-plane uniformity of the precoat film thickness is improved.

[0063] Changes in the number of particles generated when the conventional precoating method and the precoating method of the present invention were actually performed were examined. The results are shown in FIG. Here, both methods are performed twice, and the maximum number of wafers processed is set to 100.

As is apparent from this graph, in the case of the conventional method, more particles than the reference number of 30 are generated in the middle of both times, which is not preferable. On the other hand, in the case of the method of the present invention, even if 100 wafers were processed, the number of particles was not more than 30 reference particles in both cases, and it was confirmed that good results were shown.

In the description of each of the above embodiments, the discussion has been made on the premise that the precoat film 82 is attached to the lower surface of the shower head 32 and the upper surface of the mounting table 28 with substantially the same thickness. . Here, a pre-coat having substantially the same thickness on the lower surface of the shower head 32 and the upper surface of the mounting table 28. Since the investigation was made on whether or not the film 32 is deposited, the result of the examination will be described. Here, when the inside of the processing container is actually precoated and the surface of the shower head or the surface of the mounting table is precoated, a precoat film having the same thickness as the surface of the mounting table is deposited on the surface of the shower head. Verification of power was conducted.

FIG. 9 is a graph comparing the thicknesses of precoat films formed on the surfaces of the mounting table and the shower head. However, due to the configuration of the film forming apparatus, it is difficult to actually measure the thickness of the precoat film on the mounting table. Therefore, a wafer is placed on the mounting table, and the precoat film deposited on the wafer surface is used as the thickness of the precoat film deposited on the surface of the mounting table. Similarly, in order to measure the film thickness of the precoat film adhering to the surface of the shower head, it is necessary to release the inside of the apparatus itself to the atmosphere, and the measurement work is difficult. Therefore, three samples of the precoat film 82 deposited on the lower surface of the shower head 32 are sampled and measured. As is apparent from FIG. 9, the film thickness of the precoat film adhering to the mounting table (Ueno) and the film thickness of the precoat film adhering to the surface of the shower head substantially correspond to each other. Therefore, the film thickness of the precoat film adhering to the surface of the showerhead can be analogized by measuring the film thickness of the precoat film deposited on the surface of the mounting table or the surface of the wafer mounted on the mounting table. Is half IJ.

Therefore, based on the results obtained in FIG. 9, the film thickness distribution of the precoat film adhered to the surface of the shower head by the conventional precoat method and the precoat method of the present invention was examined.

FIG. 10 shows a film thickness distribution of a precoat film formed on a wafer having a diameter of 300 mm by a conventional precoat method. As shown in Fig. 10, it can be seen that the inner side of the periphery of the wafer is almost uniformly stable, whereas the film thickness of the periphery of the wafer is significantly thicker. Specifically, when a precoat film having a thickness of about 650 nm is formed, a film thickness difference of about 2 OOnm at maximum occurs. As explained in FIG. 9, it can be analogized that a precoat film is also formed on the surface of the showerhead with a similar film thickness distribution.

[0069] Therefore, when the actual film forming process is performed on the wafer, the film thickness in the peripheral part of the shower head quickly reaches the maximum film thickness A, and the film in this part peels off, resulting in a partition. Resulting in. This point is as described with reference to FIG. 7A. Next, FIG. 11 shows the result of examining the film thickness distribution of the precoat film by the method of the present invention in the same manner. As is apparent from FIG. 11, the film thickness is uniformly adhered to the entire surface of the wafer. Therefore, according to the method of the present invention, it can be presumed that the precoat film is deposited on the surface of the shower head in a uniform state, and it can be seen that generation of particles due to film peeling can be suppressed. This point is as described with reference to FIG. 7B.

In the embodiment described above, the force described by taking as an example the case where the number of cycles at the time of forming the precoat film 82 is about 33 to 40 times. This is merely an example. That is, when other metal-containing films are formed, the emissivity varies greatly depending on the film type, so it is a matter of course that the number of cycles varies depending on the emissivity and difficulty of peeling. In this case, the other metal-containing film may be a thin film containing tantalum, tantalum nitride, tungsten, tungsten nitride, or the like.

Although the case where the film forming process is performed by plasma CVD is described here as an example, the present invention is not limited to this, and the present invention can be applied to the case of film forming by thermal CVD. Any method is acceptable.

Although the semiconductor wafer is described as an example of the object to be processed here, the present invention is not limited to this, and the present invention can be applied to a glass substrate, an LCD substrate, a ceramic substrate, and the like.

Claims

The scope of the claims

[1] A method of applying a precoat in a vacuum processing container of a film forming apparatus,

A pre-coating film having a thickness X within a range represented by the following formula is formed by plasma CVD by supplying the processing gas into the processing container and storing the object to be processed. Pre-coating method:

C≤X≤A— B

[2] The precoat method according to [1], wherein the precoat film is formed by sequentially laminating a plurality of precoat layers.

[3] Each precoat layer is formed by supplying the deposition gas at the same flow rate as the deposition gas supplied when depositing a thin film on the surface of the object to be processed. The precoat method according to claim 2.

[4] A method of applying a precoat in a vacuum processing container of a film forming apparatus,

The film forming apparatus is configured to supply the processing gas into the processing container containing the target object and deposit a thin film on the surface of the target object by plasma CVD. For the pre-coating method of the membrane device!

C≤X≤D

C is a radiation saturation film thickness that is the film thickness of the precoat film such that the emissivity of the precoat film is substantially saturated;

D is the film thickness of the precoat film in which the phenomenon that the number of generated particles begins to increase suddenly when a predetermined number of semiconductor wafers are formed while gradually increasing the film thickness of the precoat film. Critical film thickness.

5. The precoat method according to claim 4, wherein the precoat film is formed by sequentially laminating a plurality of precoat layers.

[6] Each precoat layer is formed by supplying the film formation gas at the same flow rate as the flow rate of the film formation gas supplied when depositing a thin film on the surface of the object to be processed. The precoat method according to claim 5.

7. The precoat method according to claim 4, wherein the thin film is a Ti-containing film, the radiation saturated film thickness (C) is 500 nm, and the critical film thickness (D) is 720 nm.

8. The precoat method according to claim 7, wherein the thin film is formed by depositing a Ti film on the surface of the object to be processed and then nitriding at least the surface of the Ti film.

[9] A storage medium storing a program for controlling the film forming apparatus so as to execute a method of pre-coating in a vacuum processing container of the film forming apparatus,

The film forming apparatus is configured to supply the processing gas into the processing container containing the target object and deposit a thin film on the surface of the target object by plasma CVD, and the method includes: Contain the body! A storage medium characterized in that the processing gas is supplied into the processing container and a precoat film having a thickness X within a range represented by the following formula is formed by plasma CVD: C≤X≤A— B

A storage medium storing a program for controlling the film forming apparatus so as to execute a method of applying a precoat in a vacuum processing container of the film forming apparatus,

The film forming apparatus is configured to supply the processing gas into the processing container containing the target object and deposit a thin film on the surface of the target object by plasma CVD, and the method includes: Contain the body! A storage medium characterized in that the processing gas is supplied into the processing container and a precoat film having a thickness X within a range represented by the following formula is formed by plasma CVD:

C≤X≤D