JP2013007121A - Film forming apparatus and film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film forming apparatus in which even if an unnecessary adhered film deposits on the surface of a shower head part, the variation of the emissivity is suppressed, and thereby the temperature change of each workpiece can be suppressed.SOLUTION: The film forming apparatus includes: a processing vessel 4 made to be evacuable; a mounting table 24 provided within the processing vessel, for mounting a workpiece W; a heater 30 for heating the workpiece; and a shower head part 6 provided at a ceiling of the processing vessel to be opposite to the mounting table, for supplying a raw material gas for film formation, and deposits a prescribed thin film on a surface of the workpiece, wherein a surface of the shower head part is made to have an emissivity of at least 0.5 by a surface treatment. Thereby, the variation of the emissivity thereof can be suppressed even an unnecessary adhering film is deposited on the surface of the shower head part.

Description

  The present invention relates to a film forming apparatus, a film forming method, a precoat layer, and a method for forming the same, which form a thin film on a target object such as a semiconductor wafer.

In general, in order to manufacture a semiconductor integrated circuit, it is desired to repeatedly perform various single wafer processes such as a film forming process, an etching process, a heat treatment, a modification process, and a crystallization process on a target object such as a semiconductor wafer. An integrated circuit is formed.
In recent years, with regard to such an integrated circuit, the line width, the film thickness, and the like have been further miniaturized due to further demands for higher integration and thin film formation. However, since the resistivity is somewhat small, adhesion to dissimilar materials is good, and film formation at a relatively low temperature is possible, thin films using refractory metals tend to be used frequently. Examples of the site where the metal thin film is used include a wiring layer, an electrode layer, a diffusion barrier layer, and the like. Examples of the refractory metal thin film include a refractory metal thin film, a metal nitride film, a metal carbide film, and a metal silicide film.

  When the above-mentioned thin film is formed on a wafer using, for example, a single-wafer type film forming apparatus, the temperature in the processing container of the film forming apparatus is sufficiently controlled every time the wafer is processed, so that it is thermally stable. Therefore, it is necessary to make the film thickness deposited on the surface of each wafer uniform so as to maintain the uniformity of the film thickness between surfaces, that is, the reproducibility of the film thickness between wafers.

By the way, when the film forming process as described above is performed, it is avoided that unnecessary deposits that cause particles are gradually stacked and adhered to the structure in the processing container as the number of processed wafers increases. Therefore, every time a certain number of wafers are processed, a cleaning process for removing the above-mentioned unnecessary adhered film with a cleaning gas is performed regularly or irregularly.
When such a cleaning process is performed, the unnecessary adhered film is removed, so that the thermal condition in the container changes, and the change in the thermal condition prevents the wafer temperature from being affected. Therefore, before the film is actually formed on the product wafer, the film is not carried into the processing container, that is, the raw material gas for film formation is allowed to flow into the processing container in an empty state so that the precoat layer is structured in the container. A so-called pre-coating treatment for adhering to the surface of an object is performed (Patent Documents 1 and 2).

  In this pre-coating process, as described above, since the raw material gas is actually flowed into the empty container, it is desirable to shorten the time as much as possible from the viewpoint of improving the throughput. However, the pre-coating process time is too short. If the precoat treatment is insufficient, the reproducibility of the film thickness becomes insufficient. Therefore, although it depends on the type of film to be formed on the wafer and the type of film, the pre-coating process is usually performed for a time corresponding to the film formation time of several tens to several tens of wafers.

Japanese Patent Laid-Open No. 4-191379 JP-A-8-246154

By the way, as described above, even if the pre-coating process takes a certain amount of time, when the film forming process is actually performed on the product wafer, the wafer temperature is prevented from changing slightly every time the wafer is processed. In particular, there is a problem that the temperature change, that is, the film thickness change becomes large at an initial stage where the number of processed wafers is small. The reason for this temperature change is thought to be that as the wafer processing is performed as described above, the film to be deposited and its reaction intermediate are gradually deposited on the shower head unit, and the radiation rate thereof is fluctuated. .
In particular, when the film forming process is performed at a relatively low pressure, the form of heat conduction to the wafer shifts from heat conduction by gas to heat conduction by radiation, and the heat conduction by this radiation becomes dominant. There was a problem that the temperature change (film thickness change) at each time was further increased.

The present invention has been devised to pay attention to the above problems and to effectively solve them. The object of the present invention is to suppress the fluctuation of the radiation rate even if an unnecessary adhesion film is deposited on the surface of the shower head unit by setting the radiation rate of the shower head unit itself to a predetermined value or more in advance. An object of the present invention is to provide a film forming apparatus capable of suppressing a temperature change for each object to be processed.
Another object of the present invention is to provide a film forming method capable of forming a precoat layer with good thermal efficiency using the film forming apparatus.
Still another object of the present invention is to reduce the temperature difference between the mounting table and the object to be processed mounted thereon, and to suppress the temperature difference between the central portion and the peripheral portion of the mounting table. Another object of the present invention is to provide a precoat layer and a method for forming the same that can prevent the mounting table from being damaged due to thermal expansion and contraction stress.

  As a result of earnestly studying the influence of the emissivity of the shower head unit on the film thickness of the wafer surface, the present inventor has set the emissivity of the shower head unit itself to 0.5 or more in advance, thereby forming the shower head unit during film formation. Thus, the present invention has been achieved by obtaining the knowledge that even if an unnecessary adhesion film is deposited, the fluctuation amount of the wafer temperature can be greatly suppressed.

  According to a first aspect of the present invention, there is provided a processing container that can be evacuated, a mounting table that is provided in the processing container for mounting the processing object, and a heating unit that heats the processing object. And a shower head portion that is provided on the ceiling portion of the processing container so as to face the mounting table and supplies a source gas for film formation, and deposits a predetermined thin film on the surface of the object to be processed In the film forming apparatus, the surface of the shower head unit is configured so that the emissivity is set to 0.5 or more by surface treatment.

In this way, the surface of the shower head portion is configured to be set so that the emissivity is 0.5 or more by surface treatment, so even if an unnecessary adhesion film is deposited on the shower head portion during film formation, The amount of change in the temperature of the object to be processed can be greatly suppressed.
Therefore, the temperature fluctuation of the object to be processed can be suppressed for each process, so that the film thickness uniformity between the objects to be processed can be improved, and the reproducibility of the film thickness can be kept high.

In this case, for example, as defined in claim 2, the shower head portion is made of aluminum or an aluminum alloy, and an alumite layer formed by the surface treatment is provided on a surface of the shower head portion.
For example, as defined in claim 3, the base material of the shower head portion is a metal according to JIS standard A6061, and the thickness of the alumite layer is 17 μm or more.
Further, for example, as defined in claim 4, the base material of the shower head portion is a metal according to JIS standard A5052, and the thickness of the alumite layer is 28 μm or more.
For example, as defined in claim 5, the mounting table includes a resistance heater as the heating means.

When depositing a predetermined thin film on the surface of the object to be processed using the film forming apparatus according to any one of the above, the invention according to claim 6 is an empty state in which the object to be processed is not carried into the processing container. A precoat layer forming step of forming a precoat layer on at least the surface of the mounting table by flowing a predetermined gas into the processing vessel; and after the precoat layer forming step, the object to be processed is carried into the processing vessel and The film forming method is characterized in that a thin film forming step of forming the thin film on a processing body is performed.
In this case, for example, as defined in claim 7, the thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is the same as the thin film formed on the surface of the object to be processed. Made of material.

For example, as defined in claim 8, the thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is made of a silicide of the metal.
Further, for example, as defined in claim 9, the thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is a silicon film and silicidation of the metal formed on the silicon film. It consists of a two-layer structure with the object.
Thus, by setting the precoat layer to a two-layer structure, the amount of heat input to heat the object to be processed can be reduced, and the heating efficiency can be improved accordingly.

For example, as defined in claim 10, the metal-containing film is made of a nitride, carbide, silicide, or a mixture of two or more of these metals.
For example, as defined in claim 11, the metal is one or more metals selected from the group consisting of tungsten, titanium, tantalum, hafnium, and zirconium.

  According to the twelfth aspect of the present invention, the precoat layer covers the surface of the mounting table on which the object to be processed is mounted in a processing container that can be evacuated to deposit a predetermined thin film on the surface of the object to be processed. A high emissivity precoat film made of a film type having a higher emissivity than the thin film, and an upper precoat film formed on the upper layer of the high emissivity precoat film and made of the same film type as the thin film. It is the precoat layer characterized.

  Thus, a high emissivity precoat film made of a film type having a higher emissivity than the thin film deposited on the object to be processed, and an upper precoat film made of the same film type as the thin film formed on the high emissivity precoat film Since the precoat layer is formed by this, the temperature difference between the mounting table and the object to be processed placed thereon can be reduced, and the temperature difference between the central part and the peripheral part of the mounting table can be reduced. It can suppress and the damage by the thermal expansion-contraction stress of a mounting base can be prevented. In addition, the reproducibility of the film forming process can be improved.

In this case, for example, as described in claim 13, the high emissivity precoat film is formed of a material having a higher emissivity than a material constituting the mounting table.
Further, for example, as described in claim 14, the upper layer precoat film is formed on the upper surface of the mounting table except for a mounting region on which the object to be processed is directly mounted.
For example, as described in claim 15, a base precoat film made of the same film type as the thin film is formed below the upper layer precoat film.

For example, as described in claim 16, a nitride film of a material for forming a lower precoat film at the interface is formed at the interface between the precoat films.
For example, as described in claim 17, the high emissivity precoat film is made of any one of a group consisting of a silicon film, a carbon film, a SiC film, and a SiN film.
For example, as described in claim 18, the thin film is formed of a metal film or a metal-containing film.

Further, for example, as described in claim 19, the metal-containing film is made of one selected from the group consisting of a metal nitride, a carbide, and a silicide forming the metal film.
For example, as described in claim 20, the metal is at least one metal selected from the group consisting of tungsten, titanium, tantalum, hafnium, and zirconium.

The invention according to claim 21 is the formation of a precoat layer that covers the surface of the mounting table on which the object to be processed is mounted in a processing container that can be evacuated to deposit a predetermined thin film on the surface of the object to be processed. In the method, a step of forming a high emissivity precoat film made of a film type having a higher emissivity than the thin film, and a step of forming an upper layer precoat film made of the same film type as the thin film on the upper layer of the high emissivity precoat film And a method of forming a precoat layer.
In this case, for example, as described in claim 22, the step of forming the upper layer precoat film is performed in a state where the dummy object to be processed is mounted on the upper surface of the mounting table.
Further, for example, as described in claim 23, a step of forming a base precoat film made of the same film type as the thin film is performed in a pre-process of the step of forming the high emissivity precoat film.
Further, for example, as described in claim 24, immediately after each step of forming each precoat film, a nitriding step of nitriding the surface of the precoat film is performed.

According to the film forming apparatus and the film forming method of the present invention, the following excellent operational effects can be exhibited.
Since the surface of the shower head is set so that the emissivity is 0.5 or more by surface treatment, even if an unnecessary adhesion film is deposited on the shower head during film formation, the temperature of the object to be processed The amount of fluctuation can be greatly suppressed.
Therefore, the temperature fluctuation of the object to be processed can be suppressed for each process, so that the film thickness uniformity between the objects to be processed can be improved, and the reproducibility of the film thickness can be kept high.
In particular, according to the invention of claim 9, since the precoat layer is set to a two-layer structure, the amount of heat input to heat the object to be processed can be reduced, and the heating efficiency can be improved accordingly. it can.

  According to the invention which concerns on Claims 12-24, it is the same as a thin film formed in the upper layer of the high emissivity precoat film | membrane which consists of a film type with a higher emissivity than the thin film deposited on a to-be-processed object, and a high emissivity precoat film | membrane. Since the precoat layer is formed by the upper layer precoat film made of the film type, the temperature difference between the mounting table and the object to be processed placed thereon can be reduced, and the center and the periphery of the mounting table It is possible to prevent the mounting table from being damaged due to thermal expansion and contraction stress by suppressing the temperature difference between the mounting part and the part. In addition, the reproducibility of the film forming process can be improved.

It is a section lineblock diagram showing the film deposition system concerning the present invention. It is an expanded sectional view showing a shower head part in which an alumite layer was formed. It is a figure which shows the formation aspect of a precoat layer. It is a graph which shows the dependence of the wafer temperature and the wafer temperature variation | change_quantity with respect to an emissivity. It is a graph which shows the relationship between the thickness of an alumite layer with respect to an aluminum base material, and a radiation rate. It is a graph which shows the change of the sheet resistance of the thin film by this invention apparatus and a conventional apparatus. It is process drawing for demonstrating the formation method of the 1st modification of the precoat layer of this invention. It is a graph which shows the influence which the pre-coat time of tungsten has on the wafer temperature and the radiation rate of a mounting base on the conditions where a mounting base temperature is constant. It is a graph which shows the influence which the precoat time of tungsten has on the heater power and the radiation rate of a mounting base on mounting base temperature constant conditions.

In the following, an embodiment of a film forming apparatus, a film forming method, a precoat layer and a method for forming the same according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional configuration diagram showing a film forming apparatus according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a shower head portion on which an alumite layer is formed. Here, a case where a thin film of a refractory metal such as tungsten or tungsten silicide is formed as an example will be described.
As shown in the figure, this film forming apparatus 2 has a processing container 4 made of aluminum or aluminum alloy, for example, whose inside is substantially circular. In addition to a necessary processing gas, for example, W (CO) ₆ or SiH ₄ which is a raw material gas for film formation, N ₂ , Ar or the like is introduced into the ceiling portion in the processing container 4 by a gas introducing means. A certain shower head unit 6 is provided, and the processing gas is jetted out from the numerous gas jetting holes 10 provided on the gas jetting surface 8 on the lower surface toward the processing space S.

Here, the structure of the shower head unit 6 is schematically shown. In an actual apparatus, gas is separately introduced from the shower head unit 6 into the processing container 4 according to the gas type and mixed in the processing container 4. The so-called postmix structure shower head section 6 is also used. The base material of the shower head unit 6 is made of, for example, aluminum or an aluminum alloy.
Seal members 12 made of, for example, O-rings are interposed at the joints between the shower head unit 6 and the upper end opening of the processing container 4 so as to maintain the airtightness in the processing container 4. Yes.

In addition, a loading / unloading port 14 for loading / unloading a semiconductor wafer M as an object to / from the processing container 4 is provided on the side wall of the processing container 4, and the loading / unloading port 14 is opened and closed in an airtight manner. An enabled gate valve 16 is provided.
An exhaust dropping space 20 is formed in the bottom 18 of the processing container 4. Specifically, a large opening is formed in the central part of the container bottom 18, and a cylindrical partition wall 22 having a bottomed cylindrical shape extending downward is connected to the opening, and the exhaust drop is formed in the inside. A storage space 20 is formed. Further, for example, a cylindrical column 25 is provided on the bottom 22A of the cylindrical partition wall 22 that partitions the space 20, and a mounting table 24 as a holding means is fixed to the upper end of the column. ing. The wafer M is placed on the mounting table 24 and held (supported).

  The opening of the exhaust drop space 20 is set to be smaller than the diameter of the mounting table 24, and the processing gas flowing down outside the peripheral edge of the mounting table 24 wraps around the mounting table 24 to enter the space. 20 to flow into. An exhaust port 26 is formed in the lower side wall of the cylindrical partition wall 22 so as to face the exhaust drop space 20, and a vacuum pump and a pressure control valve (not shown) are provided in the exhaust port 26. The evacuated system 28 is connected so that the atmosphere in the processing container 4 and the exhaust dropping space 20 can be exhausted. Then, by automatically adjusting the valve opening degree of the pressure regulating valve, the pressure in the processing container 4 can be maintained at a constant value or can be rapidly changed to a desired pressure.

  Further, the mounting table 24 has a built-in resistance heater 30 arranged in a predetermined pattern shape as a heating means, and the outside is sintered ceramic such as AlN or the like. It is made of aluminum or an aluminum alloy, and as described above, a semiconductor wafer M as an object to be processed can be placed on the upper surface. The resistance heater 30 as the heating means is divided into a plurality of concentric zones, for example, two zones on the inner side and the outer side, and the supplied power can be independently controlled with or without being associated with each zone. Has been made. The resistance heater 30 is connected to a power supply line 32 disposed in the support column 25 so that power can be supplied while being controlled. For example, a thermocouple 33 is provided on the upper surface side of the mounting table 24 as temperature detecting means, and a lead wire 35 extending from the thermocouple 33 is drawn outside through the support column 25. The temperature of the wafer M is controlled based on the detected value of the thermocouple 33. Note that a heating lamp may be used in place of the resistance heater 30 as the heating means.

  In addition, a plurality of, for example, three pin insertion holes 34 are formed in the mounting table 24 so as to penetrate in the vertical direction (only two are shown in FIG. 1), and the pin insertion holes 34 are moved up and down. A push-up pin 36 that is inserted in a loosely fitted state is arranged. At the lower end of the push-up pin 36, a push-up ring 38 made of ceramics such as alumina formed in an arc shape lacking a part of the circular ring shape is disposed, and on the upper surface of the push-up ring 38, The lower end of each push-up pin 36 is supported.

  The arm portion 38 </ b> A extending from the push-up ring 38 is connected to a retracting rod 40 provided through the container bottom 18, and the retracting rod 40 can be moved up and down by an actuator 42. As a result, the push-up pins 36 are projected and retracted upward from the upper ends of the pin insertion holes 34 when the wafer M is transferred. In addition, an extendable bellows 44 is interposed in the through-hole portion of the bottom of the retractable rod 40 of the actuator 42 so that the retractable rod 40 can be raised and lowered while maintaining the airtightness in the processing container 4. ing.

The shower head unit 6 is connected to a gas supply system for supplying necessary processing gas. Specifically, a raw material gas supply system 46 for supplying W (CO) ₆ containing W (tungsten) metal, which is one of refractory metal materials, as a main film forming raw material gas is supplied to the shower head 6. A gas supply system that supplies other necessary gases, for example, a nitrogen gas supply system 48 that supplies nitrogen gas, a silane gas supply system 50 that supplies SiH ₄ gas, and an argon gas supply system 52 that supplies Ar gas Are connected to each other.

Since the W (CO) ₆ is solid, it is vaporized (sublimated) by heating and, for example, Ar gas is used as a carrier gas and is transported by bubbling with this Ar gas. Specifically, each gas supply system 46 to 52 has gas passages 54, 56, 58, and 60, respectively, and each gas passage 54 to 60 has an on-off valve 54 </ b> A, 56 </ b> A, 58 </ b> A, 60A is interposed, so that the start and stop of the supply of each gas can be freely controlled. In addition, a flow rate controller (not shown) such as a mass flow controller is provided on the upstream side of each gas passage 46 to 60 so that the flow rate of the supplied gas can be controlled.

  As a feature of the present invention, the surface of the shower head 6 is set so that the emissivity is 0.5 or more by surface treatment. Specifically, the surface of the shower head portion 6 made of aluminum or aluminum alloy, that is, the surface facing the inside of the processing container 4 of the shower head portion 6, for example, the gas injection surface 8 or its side surface is anodized as a surface treatment. The alumite layer 62 is formed on this surface as shown in FIG. The thickness H1 of the alumite layer 62 is, for example, about 17 to 50 μm, and is set so that the emissivity is 0.5 or more as described above, although it depends on the type of the base material forming the shower head portion 6. Is done. In this way, when the emissivity of the shower head unit 6 is set to be 0.5 or more, the wafer is formed when the film is formed on the product wafer after the precoat layer is applied as described later. It is possible to improve the uniformity of the film thickness between the surfaces by suppressing the temperature fluctuation (change) between them.

  In order to perform various controls such as the start and stop of supply of various gases, the wafer temperature, and the process pressure of the entire film forming apparatus 2, a control means 64 such as a microcomputer is provided. . The control means 64 has a storage medium 66 for storing a program for performing the above-described control. The storage medium 66 is composed of, for example, a flexible disk, a CD-ROM, a DVD, a hard disk, and a flash memory.

Next, the operation of the film forming apparatus configured as described above will be described with reference to FIG. As described above, each operation described below is performed based on the program stored in the storage medium 66. FIG. 3 is a diagram showing a form of forming the precoat layer.
<Precoat treatment>
First, when the inside of the processing container 4 is immediately after the cleaning process, the film forming process is not directly performed on the product wafer, and the thermal conditions such as the radiation rate in the processing container 4 are stabilized as described above. Therefore, a precoat film forming step is performed. In this precoat film forming step, for example, a raw material gas or other necessary gas is allowed to flow under the same or similar process conditions as those for film formation on a product wafer, and at least the surface of the mounting table 24 is precoated as shown in FIG. Layer 70 is formed.

  In this case, each of the precoat layers 70 may have, for example, a single-layer structure as shown in FIG. 3 (A), or a previously formed lower layer film 70A and an upper layer thereof as shown in FIG. 3 (B). Alternatively, a two-layer structure including the upper layer 70B formed in the above may be used.

  As shown in FIG. 3A, when the precoat layer 70 has a single-layer structure, it may have a single-layer structure of a tungsten (W) film that is a metal metal film included in a thin film formed on a product wafer. A single-layer structure of a metal-containing film containing the above metal, for example, a tungsten silicide (WSi: tungsten silicide) film may be used.

As shown in FIG. 3B, when the precoat layer 70 has a two-layer structure, the first lower layer film 70A is a silicon film, for example, a polysilicon film, and the second upper layer film 70B is made of the above metal. It is good also as a metal containing film | membrane containing, for example, a tungsten silicide (WSi) film | membrane. In this case, the first silicon film can be formed by using SiH ₄ and Ar. When the second WSi film is formed, W (CO) ₆ may be flown simultaneously, and a purge process may be performed between SiH ₄ and W (CO) _{6 as} will be described later. Alternatively, a film may be formed by alternately and repeatedly flowing a plurality of times while sandwiching the film. Of course, the precoat layer 70 may have a structure of three or more layers.
If the desired precoat layer 70 is formed as described above, the process proceeds to a thin film forming process for forming a thin film on the product wafer.

<Thin film formation process>
In this thin film forming step, first, prior to the transfer of the semiconductor wafer M, for example, the inside of the processing container 4 of the film forming apparatus 2 connected to a load lock chamber (not shown) is evacuated, for example. The mounting table 24 to be mounted is heated to a predetermined temperature by a resistance heater 30 as a heating means and is stably maintained.

  In such a state, first, an unprocessed, for example, 300 mm semiconductor wafer M is loaded into the processing container 4 through the gate valve 16 and the loading / unloading port 14 which are opened by being held by a transfer arm (not shown). Then, after the wafer M is delivered to the raised push-up pins 36, the push-up pins 36 are lowered to place the wafer M on the upper surface of the mounting table 24 and support it.

Next, each processing gas including the raw material gas is supplied to the shower head unit 6 while controlling the flow rate, and at the same time, the vacuum pump provided in the vacuum exhaust system 28 is continuously driven, so that the inside of the processing container 4 and the exhaust dropping space are provided. The atmosphere in 20 is evacuated, and the opening degree of the pressure regulating valve is adjusted to maintain the atmosphere in the processing space S at a predetermined process pressure. As a result, a tungsten film is formed as a metal-containing film on the surface of the semiconductor wafer M.
Such a film forming process is performed continuously by replacing the processed semiconductor M with an unprocessed wafer.

  Here, in the present invention, since the alumite layer 62 is formed on the surface of the shower head unit 6 and this emissivity is set to be large in advance to be 0.5 or more, the product wafer is subsequently formed. Even if an unnecessary adhesion film is deposited, the change in the wafer temperature with respect to the change in the emissivity can be reduced. In other words, if the emissivity is set to 0.5 or more in advance, even if the emissivity is further increased by subsequent film formation on the wafer, the change in the wafer temperature is not so large, and this temperature change is suppressed. be able to. Therefore, the temperature difference between the wafers can be suppressed by increasing the radiation rate of the surface of the shower head unit 6 to 0.5 or more.

Since the temperature difference between the wafers can be suppressed in this way, the difference in film thickness formed on each wafer can be suppressed, and as a result, the uniformity of the film thickness can be greatly improved.
In this case, in order to set the emissivity of the surface of the shower head 6 to 0.5 or more, the thickness of the anodized layer 62 is used when an aluminum alloy according to JIS A6061 is used as the base material of the shower head 6. The thickness H1 is set to 17 μm or more, and when an aluminum alloy according to JIS standard A5052 is used as the base material of the shower head unit 6, the thickness H1 of the alumite layer 62 is set to 28 μm or more.

  In addition, when a precoat layer having a two-layer structure as shown in FIG. 3B is applied as the precoat layer 70, the wafer can be removed from the surface of the mounting table 24 as compared with a metal film or a metal-containing film single film. The radiation to M can be further adjusted. As a result, the wafer can be heated to a desired process temperature with a small amount of power input to the resistance heater 30, and the heating efficiency to the wafer M can be improved.

<Dependence of emissivity on wafer temperature>
Next, an experiment for evaluating the dependence of the wafer temperature on the emissivity was performed, and the evaluation result will be described.
FIG. 4 is a graph showing the dependence of the wafer temperature and the wafer temperature change amount on the emissivity. Here, changes in the wafer temperature and the emissivity when a tungsten film was formed on the surface of a large number of wafers in a film forming apparatus having a conventional shower head portion in which an alumite layer was not provided in the shower head portion were examined. The temperature of the mounting table is set to 691 ° C. In FIG. 4, the horizontal axis represents the emissivity, the left vertical axis represents the wafer temperature, and the right vertical axis represents the wafer temperature change (the change in wafer temperature relative to the change in emissivity 0.1). ing.

  Here, as the number of processed wafers increases, more unnecessary adhesion films adhere to the shower head portion, so that the emissivity gradually increases. When the emissivity is between 0.2 and 0.8, the process of forming a tungsten film with a thickness of 50 nm on one wafer is performed on 50 wafers. The wafer temperature has changed from 526 ° C. to 401 ° C. as much as 125 ° C. with respect to the change in the emissivity of the shower head portion from 0.8 to 0.2. It will appear as a change in thickness.

When attention is paid to the amount of change in wafer temperature, the amount of change in wafer temperature gradually decreases as the radiation rate increases. As the emissivity changes and the wafer temperature changes, the change in wafer temperature with respect to the change in emissivity decreases as the emissivity increases.
Therefore, it can be seen that if the emissivity of the shower head portion is increased in advance, even if the emissivity is increased by the subsequent film formation on the wafer, the decrease in the wafer temperature does not increase so much. Therefore, in the present invention, paying attention to this point, an alumite layer 62 (see FIG. 2) is provided in advance in the shower head portion and the emissivity is set to be 0.5 or more. It was confirmed that the amount of change in wafer temperature per 1 can be suppressed to 18 ° C. or less. In this case, it is more preferable to set the emissivity to 0.8 or more because the amount of change in wafer temperature can be made 10 ° C. or less. As described above, since the change amount of the wafer temperature can be set to 18 ° C. or less, the change amount of the film thickness formed on the wafer can be greatly suppressed and reduced. The uniformity can be greatly improved.

<Examination of showerhead base material>
Next, since the examination of the base material of the shower head unit 6 was performed, the examination result will be described.
Here, as a base material for forming the shower head portion 6, an aluminum alloy defined by JIS standards A5052 and A6061 was examined. FIG. 5 is a graph showing the relationship between the thickness of the anodized layer and the emissivity with respect to the aluminum base material. As described above, JIS standard A5052 and A6061 aluminum alloys were examined here.

As is clear from the graph shown in FIG. 5, in order to obtain the emissivity of 0.5 or more obtained in FIG. 4, it is necessary to form an alumite layer having a thickness of 17 μm or more in the case of A6061 aluminum alloy. In the case of A5052 aluminum alloy, it has been confirmed that it is necessary to form an alumite layer having a thickness of 28 μm or more.
The material of these shower head portions 6 is merely an example, and any aluminum or aluminum alloy may be used as long as the emissivity is 0.5 or more.

<Evaluation according to the present invention and a comparative example>
Next, the pre-coating process and the film forming process were actually performed using the apparatus of the present invention, and the evaluation was performed in comparison with the comparative example using the conventional apparatus. The evaluation result will be described.
The evaluation results are summarized in Table 1 below, and FIG. 6 is a graph showing changes in sheet resistance of the thin film by the device of the present invention and the conventional device. The sheet resistance corresponds to the film thickness.

Here, as a comparative example, a tungsten film is formed on a wafer using a conventional apparatus (without an alumite layer), and a tungsten film is formed as a precoat layer. In addition, a tungsten film is formed using the apparatus of the present invention (with an alumite layer), and in this case, as a precoat layer, a single-layer precoat layer made of a tungsten film is formed (see FIG. 3A). ) And a two-layer precoat layer composed of a polysilicon film and a WSi film (see FIG. 3B).
Here, a tungsten film is continuously formed on 50 wafers, and the wafer temperature change amount of the 50 wafers is obtained. The average value of 25 sheets is obtained for the amount of change in sheet resistance. FIG. 6 shows changes in sheet resistance values of the 25 wafers. In FIG. 6, the description of data in the case of a precoat layer having a single layer structure is omitted.

The process conditions by each apparatus are as follows.
[Pre-coating conditions for conventional equipment]
Mounting table temperature: 550 ° C
Process pressure: 6.7 Pa
Ar carrier gas / diluted Ar gas for W (CO) ₆ = 90/700 sccm
Deposition time: 2400 sec
Precoat layer type: W film

[Pre-coating conditions of the device of the present invention for a single pre-coating layer]
Same as in the case of the above-mentioned conventional device Type of precoat layer: single layer structure of W film

[Pre-coating conditions of the device of the present invention for a two-layer pre-coating layer]
Mounting table temperature: 591 ° C
Process pressure: 6.7 Pa (constant)
First layer (lower layer film): Formation of a polysilicon film
Ar / SiH ₄ = 600/100 sccm
Deposition time: 360 sec
Second layer (upper layer film): Formation of WSi film (repeat 1 to 4 steps below 33 times)
1 step: Ar / SiH ₄ = 200/100 sccm, time: 5 sec
2step: purge Ar = 300 sccm, time: 10 sec
3step: Ar carrier gas / diluted Ar gas for W (CO) ₆ = 60/240 sccm, time: 5 sec
4step: purge Ar = 300 sccm, time: 10 sec
Precoat layer type: PolySi film / WSi film two-layer structure

[Process conditions for wafer deposition]
Same conditions for both the conventional device and the present device Wafer temperature: 500 ° C
Process pressure: 20Pa
Ar carrier gas / diluted Ar gas for W (CO) ₆ = 90/700 sccm
Deposition time: 340 sec
The above results are shown in Table 1 below.

  As is apparent from Table 1, in the case of the conventional apparatus, the temperature of the first wafer is greatly changed by 125 ° C. from the wafer temperature of 526 ° C. to the wafer temperature of 50 wafers of 104 ° C., and the sheet resistance of the 25 wafers at that time The in-plane uniformity of the value is also unfavorably changed to 8.8%. The sheet resistance value corresponds to the film thickness as is well known, and the change in the film thickness can be recognized by looking at the change in the sheet resistance value.

On the other hand, in the case of the pre-coating layer having a single-layer structure, the apparatus of the present invention changes only 14 ° C. from the first wafer temperature 501 ° C. to the 50th wafer temperature 487 ° C. It was confirmed that changes in wafer temperature can be suppressed. Further, the uniformity between the sheet resistance values of the 25 wafers at that time was 3.1%, which was greatly suppressed as compared with the case of the conventional apparatus, and it was confirmed that good results were obtained.
In the case of the precoat layer having a two-layer structure, only 12 ° C. is changed from the first wafer temperature of 500 ° C. to the 50th wafer temperature of 488 ° C., confirming that the change in the wafer temperature can be extremely suppressed. did it. In addition, it was confirmed that the uniformity between the sheet resistance values of the 25 wafers at that time was 2.9%, which can be further suppressed as compared with the case of the conventional apparatus, and a good result was obtained. FIG. 6 shows a change in sheet resistance in the case of the two-layer structure precoat layer of the conventional device and the device of the present invention at this time.

  Further, as is apparent from Table 1, in the apparatus of the present invention, in order to maintain the wafer temperature at a substantially constant temperature, when the precoat layer having a single layer structure is employed, the temperature of the mounting table is maintained at 780 ° C. However, if a two-layered precoat layer is used, the temperature of the mounting table may be maintained at 682 ° C., which is 98 ° C. lower than 780 ° C. Therefore, when the precoat layer having the two-layer structure is adopted, the input power can be reduced, and the energy efficiency can be increased correspondingly, thereby contributing to energy saving.

<Modification of precoat layer>
Next, a modified example of the precoat layer formed on the surface of the internal structure such as the mounting table will be described.
FIG. 7 is a process diagram for explaining a method for forming a first modified example of the precoat layer of the present invention. FIG. 8 is a diagram illustrating a tungsten precoat time and radiation of the mounting table under a constant mounting table temperature. FIG. 9 is a graph showing the influence of the precoat time of tungsten on the heater power and the radiation rate of the mounting table under the condition that the mounting table temperature is constant.

As described above, the precoat layer made of the same material as the film type to be deposited on the wafer is formed to stabilize the thermal conditions in the processing container 4 after cleaning the processing container, As a result, the impurities released from the mounting table 24 and the resistance heater 30 are blocked to prevent the wafer M from being contaminated, and the difference in film thickness between the wafers successively formed one by one is suppressed. Thus, the reproducibility of the film forming process is improved.
At this time, if the precoat layer is excessively thick, the heat radiation from the mounting table to the wafer itself is reduced, and the difference between the mounting table temperature and the wafer temperature (temperature difference) increases. Since power must be input, the life of the heater and the like is shortened.

  Therefore, the precoat layer in the mounting table area on which the wafer is placed in direct contact is thinned, and a precoat layer is further deposited in a state where a dummy wafer is used to form a thick precoat layer on the peripheral edge of the mounting table. Is also done. In this case, the temperature difference between the mounting table and the wafer can be reduced, but when the mounting table is emptied to load and unload the wafer, the heat dissipation amount in the mounting region is compared with the surrounding area. As a result, the temperature difference between the central part and the peripheral part of the mounting table becomes too large, and the mounting table itself may be damaged by this thermal stress.

  In this modification, the above problems are solved by appropriately combining a film type deposited on the wafer, for example, a tungsten film (W film) and a film type having a higher emissivity, for example, a silicon film (Si film). Like to do.

First, with reference to FIG. 7, the structure of the 1st modification of a precoat layer and its formation method are demonstrated. In addition, the same code | symbol is attached | subjected about the same component as the component demonstrated with reference to previous drawing. FIG. 7E shows a complete precoat layer, and this mounting table 24 is used in a film forming apparatus as shown in FIG. 1, for example, and forms a tungsten film on the wafer M, for example.
The mounting table 24 is made of ceramic such as aluminum nitride (AlN), alumina (Al ₂ O ₃ ), or silicon carbide (SiC), aluminum, aluminum alloy, or the like. Here, the mounting table 24 is made of, for example, AlN. Shall. In addition, description of a resistance heater, a pin insertion hole, etc. is abbreviate | omitted. In the matters described below, the lower layer refers to the side closer to the mounting table 24, and the upper layer refers to the side far from the mounting table 24.

First, as a film that is in direct contact with the lowermost layer of the precoat layer 80, that is, the surface of the mounting table 24, a base precoat film 80A made of the same film type as the thin film formed on the wafer, that is, a W film is formed on the entire surface. ing.
A high emissivity precoat film 84 is formed on the entire surface of the base precoat film 82 via a tungsten nitride film (WN) 82A, which is a nitride film of the material forming the base precoat film 82, at the interface. Yes. The tungsten nitride film 82A functions as a barrier layer. The high emissivity precoat film 84 is formed of a film type to be formed on the wafer, that is, a film type having a higher emissivity than the tungsten film, for example, a silicon film (Si) here. As a material of the high emissivity precoat film 84, it is preferable to select a material having a higher emissivity than the material constituting the mounting table 24, for example, AlN.

  Next, an upper precoat film 86 is formed on the high emissivity precoat film 84 via a silicon nitride film (SiN) 84A, which is a nitride film of a material for forming the high emissivity precoat film 84, at the interface. ing. The silicon nitride film 84A is formed on the entire surface and functions as a barrier layer for the upper precoat film 86.

  The upper precoat film 86 is formed of the same material as the film type to be formed on the wafer, for example, a tungsten film. The upper precoat film 86 is not formed in the mounting area 90 where the wafer is directly mounted, but is formed over the entire other surface. As will be described later, the upper layer precoat film 86 can be formed by performing a film formation process in a state where a dummy wafer (dummy object) DM is mounted on the mounting table 24. Regarding the emissivity, generally, W is about 0.15 to 0.20, Si is about 0.65, WSi is about 0.3 to 0.5, WN and SiN are W and Si, respectively. It is about the same.

Next, a method for forming the precoat layer 80 will be described.
First, as shown in FIG. 7A, a base precoat film 82 is formed on the surface of the mounting table 24 by forming tungsten using W (CO) ₆ as a source gas.
The process conditions at this time are as follows.
Mounting table temperature: 550 ° C
Process pressure: 6.7 Pa
Ar carrier gas / diluted Ar gas for W (CO) ₆ = 40/320 sccm
Deposition time: 60 sec

Next, as shown in FIG. 7B, the surface of the base precoat film 82 was nitrided using NH ₃ gas to form a nitride film (WN) 82A.
The process conditions at this time are as follows.
Mounting table temperature: 600 ° C
Process pressure: 133.3 Pa
Gas flow rate: Ar / NH ₃ = 50/310 sccm
Process time: 60 sec

Next, as shown in FIG. 7C, silicon was deposited on the base precoat film 82A using SiH ₄ gas as a source gas to form a high emissivity precoat film 84.
The process conditions at this time are as follows.
Mounting table temperature: 600 ° C
Process pressure: 326.6 Pa
Gas flow rate: Ar / SiH ₄ = 600/100 sccm
Deposition time: 1800 sec

Next, as shown in FIG. 7D, the surface of the high emissivity precoat film 84 is nitrided using NH ₃ gas to form a nitride film (SiN) 84A (FIG. 7D).
The process conditions at this time are as follows.
Mounting table temperature: 600 ° C
Process pressure: 133.3 Pa
Gas flow rate: Ar / NH ₃ = 50/310 sccm
Process time: 60 sec

Next, as shown in FIG. 7E, tungsten was deposited on the nitride film 84A to form an upper precoat layer 86. The film thickness of the upper precoat layer 86 is set such that the radiation rate on the surface of the mounting table converges (saturates). In this case, the film formation process was performed in a state where the dummy wafer DW was previously placed on the placement table 24 so that the tungsten film was not deposited on the placement region 90. Further, in order to increase the deposition rate of the precoat film, the mounting table temperature was made the same as that during the wafer film formation process.
The process conditions at this time are as follows.
Mounting table temperature: 675 ° C
Process pressure: 20Pa
Ar carrier gas / dilution gas for W (CO) ₆ = 90/700 sccm
Deposition time: 300 sec

  As described above, after the precoat layer 80 was formed, a tungsten film was continuously formed on the product wafer. By setting the temperature of the mounting table 24 at this time to 675 ° C. (wafer temperature: 500 ° C.), the wafer temperature could be maintained at the target temperature of 500 ° C. That is, the temperature difference between the mounting table 24 and the wafer M is 175 ° C., and the temperature difference between the two can be made smaller by suppressing the temperature difference than the conventional 279 ° C., for example.

The difference in film thickness between the 25 wafers was ± 6.0% when the sheet resistance was measured and converted, and the reproducibility of the film thickness could be greatly improved.
Further, the mounting table 24 itself was not damaged, and this durability was improved and the life could be extended.
As described above, the high emissivity precoat film 84 made of a film type having a higher emissivity than the thin film deposited on the semiconductor wafer M as the object to be processed and the upper precoat film 86 made of the same film type as the thin film are appropriately combined. Since the precoat layer 80 is formed, the temperature difference between the mounting table 24 and the target object W mounted thereon can be reduced, and between the central portion and the peripheral portion of the mounting table 24. The temperature difference can be suppressed and the mounting table 24 can be prevented from being damaged due to thermal expansion and contraction stress. In addition, the reproducibility of the film forming process can be improved.

Here, the effect | action of each film | membrane in the precoat layer 80 of the said 1st modification is demonstrated in detail.
<First purpose of precoat>
In a high-temperature process, a mounting table 24 in which a resistance heater 30 is embedded in a heat-resistant ceramic material is generally used. The ceramic material contains impurities such as a sintering aid, and the impurities are released at a high temperature, which may contaminate the back surface of the wafer when the wafer is mounted. Further, the surface of the mounting table becomes fragile due to corrosion by the cleaning gas when the processing container 4 is cleaned, and a large amount of particles adhere to the back surface of the wafer when the wafer is mounted.

  Therefore, as a pre-stage for starting film formation on the product wafer, generally, at least the surface on which the wafer is placed / contacted is coated with a precoat film on the mounting table with the same film as the film formed on the wafer, Avoid the above problems. Here, this precoat film becomes the base precoat film 82.

<Adverse effects of precoat>
However, in the case of a material having a low emissivity such as a metal film such as a W film, if the precoat film on the surface of the mounting table is made thicker by precoating, the actual wafer performance is maintained even if the temperature of the mounting table 24 is kept constant. The temperature decreases as the precoat film thickness increases. In particular, when the film forming condition on the wafer is a low pressure of 1 Torr or less, the heat conduction from the mounting table 24 to the wafer is dominated by radiation, and the wafer temperature changes greatly due to the change of the radiation rate on the surface of the mounting table. Since the emissivity of the constituent material (AlN) of the mounting table 24 is higher than that of the metal film as in this embodiment, it is affected by the emissivity of the constituent material while the precoat film is thin. Convergence to emissivity.

  The state at this time is shown in FIG. 8, and even if the mounting table temperature is kept constant at 550 ° C., both the wafer temperature and the mounting table radiation rate gradually decrease as the tungsten pre-coating time increases. , Finally has converged to a low value. This means that the emissivity decreases as the precoat film becomes thicker, and the temperature difference between the mounting table and the wafer gradually increases. As described above, when the radiation rate of the surface of the mounting table is lowered, the heating efficiency of the wafer by the heater is extremely lowered in the low-pressure process. Therefore, in order to maintain the predetermined wafer temperature, it is necessary to greatly increase the temperature of the mounting table. There is.

  In the high-temperature film forming process as in this example, the pre-coating process has to increase the set temperature of the heater accordingly, which places a heavy burden on the mounting table and heater, and shortens the service life. become.

<Countermeasures for temperature drop>
Therefore, after the mounting table is once covered with a base precoat film 82 made of a metal film made of a W film, at least the substrate mounting / contacting surface of the mounting table is made of a high emissivity precoat with a non-metallic material such as Si having a high emissivity. Cover with membrane 84. If the emissivity of the mounting table, for example, Si higher than that of AlN, is used, the emissivity on the surface of the mounting table can be restored to the original AlN level even with a thin coating. Further, by depositing the Si film sufficiently thick, a radiation rate higher than that of AlN becomes possible.

  When coating the Si film, the surface of the base metal film is nitrided before the Si coating so that it reacts with the base metal (W) film to become metal silicide (WSi) and does not reduce the emissivity. Then, a nitride film (WN) 82A is formed as a barrier layer. In general, a silicon nitride film or a metal nitride film has a barrier function for preventing a reaction between the two by sandwiching it between materials that easily react with each other.

<Second purpose of precoat>
In the mounting table 24 of the embodiment, the embedded region of the resistance heater 30 is, for example, two zones, the inner side and the outer side, and the temperature distribution of the mounting table 24 can be adjusted by setting the input power ratio of each zone. It is like that. However, as the film forming process is repeated on the wafer, a film is deposited on the surface other than the wafer mounting surface of the mounting table 24, and as a result, the radiation rate of this portion decreases. If the radiation rate of the mounting table 24 partially changes, the heat radiation balance of the entire mounting table 24 is lost, and the in-plane thermal uniformity of the wafer cannot be maintained at the set zone power ratio, and the film formation distribution on the wafer deteriorates. become. Therefore, in order to prevent the emissivity of the portion other than the wafer mounting surface of the mounting table 24 from being changed by the film forming process on the wafer, the same metal film as that for the wafer film formation, for example, a W film is formed on this portion in advance with a predetermined thickness. It is necessary to form the upper layer precoat film 86 by deposition. The predetermined film thickness is a film thickness at which the emissivity of the surface of the mounting table 24 converges (saturates).

<Precoat with dummy wafer>
As described above, it is radiation from the wafer mounting surface (mounting area) of the mounting table 24 that mainly heats the wafer. Therefore, the radiation rate of this portion is not changed (maintained high), and the upper layer is heated. A precoat film 86 is deposited. For this purpose, it is necessary to carry out the pre-coating of the metal film (W film) while the dummy wafer DW is mounted, and to continue the pre-coating process until the radiation rate of the entire mounting table converges (saturates). The overall emissivity is uniquely correlated with the input power, and when this converges, the emissivity converges. On the opposite side of the mounting table from the wafer mounting surface, it is difficult to deposit the precoat film, and it takes a long time to deposit the precoat film by a predetermined thickness on the entire mounting table.

  FIG. 9 shows the situation at this time. In order to maintain the mounting table temperature at 550 ° C., the input power gradually decreases in both the inner zone and the outer zone as the precoat time becomes longer, and similarly the radiation rate is increased. However, the heater input power and the emissivity are substantially converged (saturated) after a long time, for example, about 4000 sec. Also in this case, in the pre-process for depositing the W film, the high-emissivity precoat film 84 is formed in advance so that the upper precoat film 86 made of the metal film does not react with the high-emissivity precoat film 84 made of the underlying Si film. A SiN film 84A, which is a nitride film having a barrier function, is formed by nitriding the surface. The pre-coating layer 86 formed as described above can exhibit the above-described effects.

<Comparative example>
As a comparative example, only the W film was formed on the same surface of the same mounting table 24 as described in FIG.
Mounting table temperature: 550 ° C
Process pressure: 6.7 Pa
Ar carrier gas / diluted Ar gas for W (CO) ₆ = 40/320 sccm
Deposition time: 2400 sec
In this case, the mounting table temperature is set to 675 ° C., which is the same as the mounting table temperature when the W film is formed on the product wafer. However, the actual temperature of the wafer only rises to 372 ° C., and a predetermined wafer temperature of 500 ° C. is set. Could not be achieved.

  In the first and second modifications described here, a nitride film of a base film material that functions as a barrier layer, such as a WN film or a SiN film, is interposed at the interface between the overlapping precoat films. It may be omitted so that these nitride films are not interposed. When the nitride film is not interposed as described above, metal silicide that slightly lowers the emissivity, for example, WSi, is naturally generated at the boundary portion. Can be demonstrated.

In the first and second modified examples, the Si film is described as an example of the high emissivity precoat film 84. However, the present invention is not limited to this, and any of the group consisting of a silicon film, a SiC film, and a SiN film is used. One material can be used.
In the above-described embodiments (including modifications), the case where a metal film made of a tungsten film is formed on the wafer has been described as an example. However, the present invention is not limited to this, and a metal-containing film containing a tungsten film, for example, a nitride The present invention can also be applied when forming a film, a carbide film, a silicide film, or a mixture film thereof.

In addition, the case where tungsten, which is a refractory metal, is used as the metal has been described as an example. However, the present invention is also applied to the case where another refractory metal such as titanium, tantalum, hafnium, zirconium, or the like is used. be able to. In this case, it is a matter of course that the silicide used for the precoat layer is a metal silicide contained in a thin film formed on the semiconductor wafer.
Of course, the present invention can also be applied when the thin film formed on the semiconductor wafer is not a metal film or a metal-containing film, for example, a silicon film or a silicon oxide film.

The film formation described here is merely an example, and any film forming apparatus having a shower head can be applied. For example, the present invention can also be applied to a film forming apparatus using plasma. .
Further, in this embodiment, the semiconductor wafer is described as an example of the object to be processed, but the present invention is not limited to this, and it is needless to say that the present invention can be applied to an LCD substrate, a glass substrate, a ceramic substrate, and the like.

2 Deposition device 4 Processing vessel 6 Shower head (gas introduction means)
8 Gas injection surface 24 Mounting table (holding means)
28 Vacuum exhaust system 30 Resistance heater (heating means)
62 alumite layer 64 control means 66 storage medium 70 precoat layer 70A lower layer film 70B upper layer film 80 precoat layer 82 underlayer precoat film (W)
82A Nitride film (WN)
84 High emissivity precoat film (Si)
84A Nitride film (SiN)
86 Upper layer precoat film (W)
96 Placement area M Semiconductor wafer (object to be processed)
DM dummy wafer (dummy workpiece)

The present invention relates to the deposition equipment and a film forming method for forming a thin film on the object to be processed such as a semiconductor wafer.

The present invention has been devised to pay attention to the above problems and to effectively solve them. The object of the present invention is to suppress the fluctuation of the radiation rate even if an unnecessary adhesion film is deposited on the surface of the shower head unit by setting the radiation rate of the shower head unit itself to a predetermined value or more in advance. An object of the present invention is to provide a film forming apparatus capable of suppressing a temperature change for each object to be processed.
Another object of the present invention is to provide a film forming method capable of forming a precoat layer with good thermal efficiency using the film forming apparatus.
Still another object of the present invention is to reduce the temperature difference between the mounting table and the object to be processed mounted thereon, and to suppress the temperature difference between the central portion and the peripheral portion of the mounting table. in subjecting Hisage the deposition method is Ru can be prevented to damage due to thermal expansion and contraction stress of the mounting table.

According to a first aspect of the present invention, there is provided a processing container that can be evacuated, a mounting table that is provided in the processing container for mounting the processing object, and a heating unit that heats the processing object. And a shower head portion that is provided on the ceiling portion of the processing container so as to face the mounting table and supplies a source gas for film formation, and deposits a predetermined thin film on the surface of the object to be processed In the film forming apparatus, the shower head portion is surface-treated so that the emissivity at an infrared wavelength emitted when the temperature of the object to be processed is 401 to 526 ° C. is 0.5 or more. Is a film forming apparatus.

According to a second aspect of the present invention, there is provided a processing container that can be evacuated, a mounting table that is provided in the processing container for mounting the processing object, and a heating unit that heats the processing object. And a shower head portion that is provided on the ceiling portion of the processing container so as to face the mounting table and supplies a source gas for film formation, and deposits a predetermined thin film on the surface of the object to be processed In the film forming apparatus, the shower head portion is surface-treated so that the temperature change amount of the object to be processed per emissivity change of 0.1 is 18 ° C. or less. is there.
For example, as defined in claim 3, the shower head portion is made of aluminum or an aluminum alloy, and an alumite layer formed by the surface treatment is provided on a surface of the shower head portion.
For example , as defined in claim 4, the base material of the shower head portion is a metal according to JIS standard A6061, and the thickness of the anodized layer is 17 μm or more.
Further, for example , as defined in claim 5, the base material of the shower head portion is a metal according to JIS standard A5052, and the thickness of the alumite layer is 28 μm or more.
For example , as defined in claim 6, the mounting table includes a resistance heater as the heating means.

Invention, when depositing a predetermined thin film on the surface of the object to be processed using the film forming apparatus according to any one of claims 1乃optimum 6, wherein the object to be processed into the processing container according to claim 7 A pre-coating layer forming step of forming a pre-coating layer on at least the surface of the mounting table by flowing a predetermined gas into the processing vessel in an empty state where no body is carried in, and the pre-coating layer forming step after the pre-coating layer forming step. It is a film forming method characterized by carrying out a thin film forming step of carrying in a processing body and forming the thin film on the object to be processed.
In this case, as specified for example in請Motomeko 8, wherein the thin film is a metal film or a metal-containing film, the pre-coat layer of the precoat layer forming step, said thin film in which the formed on the surface of the object Made of the same material.

For example , as defined in claim 9, the thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is made of a silicide of the metal.
Further, for example , as defined in claim 10, the thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is a silicon film and silicidation of the metal formed on the silicon film. It consists of a two-layer structure with the object.
Thus, by setting the precoat layer to a two-layer structure, the amount of heat input to heat the object to be processed can be reduced, and the heating efficiency can be improved accordingly.

For example , as defined in claim 11, the metal-containing film is made of a nitride, carbide, silicide, or a mixture of two or more of these metals.
For example , as defined in claim 12, the metal is at least one metal selected from the group consisting of tungsten, titanium, tantalum, hafnium, and zirconium.

The related art of the present invention relates to a precoat layer that covers a surface of a mounting table on which the object to be processed is mounted in a processing container that can be evacuated to deposit a predetermined thin film on the surface of the object to be processed. A high emissivity precoat film made of a film type having a higher emissivity than the thin film, and an upper precoat film made of the same film type as the thin film formed on the upper layer of the high emissivity precoat film. It is a precoat layer.

In this case, the high emissivity pre-coating film if example embodiment, the emissivity are formed in high material than the material constituting the mounting table.
Also, the upper layer pre-coating film For example, in a top surface of the mounting table is formed with the exception of the placement area directly mounting the object to be processed.
Also in the lower layer of the upper layer pre-coating film if example embodiment, the base pre-coating film made of the same film type and the thin film is formed.

Also at the interface between the respective pre-coating film In example embodiment, the nitride film of the material forming the underlying pre-coating film in the interface is formed.
The high emissivity pre-coating film if example embodiment also, the silicon film, carbon film, SiC film, consisting of any one of the group consisting of SiN film.
Also, the thin film if example embodiment, made of a metal film or a metal-containing film.

Also, the metals-containing film For example, the nitride of a metal forming the metal film, carbides, consisting of 1 selected from the group consisting of silicide.
The metal In example embodiment also, tungsten, any one or more metals of the group consisting of titanium, tantalum, hafnium, from zirconium.

For example, as described in claim 13, the precoat layer forming step includes a step of forming a high emissivity precoat film made of a film type having a higher emissivity than the thin film, and an upper layer of the high emissivity precoat film. Forming an upper precoat film made of the same film type as the thin film .
Further, for example, as described in claim 14, the precoat layer is formed on a high emissivity precoat film made of a film type having a higher emissivity than the thin film, and an upper layer of the high emissivity precoat film. And an upper precoat film made of the same film type.
Further, as described in claim 15 In example embodiment, the step of forming the upper layer pre-coating film is performed while placing the dummy workpiece on the upper surface of the mounting table.
Further, for example, as described in claim 16, the upper layer precoat film is formed on the upper surface of the mounting table except for a mounting region on which the object to be processed is directly mounted.
Further, for example , as described in claim 17, a step of forming a base precoat film made of the same film type as the thin film is performed in a step preceding the step of forming the high emissivity precoat film.
Further, for example , as described in claim 18, a nitriding step of nitriding the surface of the precoat film is performed immediately after each step of forming the precoat film.
For example, as described in claim 19, a nitride film of a material for forming a lower precoat film at the interface is formed at the interface between the precoat films.
Further, for example, as described in claim 20, the high emissivity precoat film is formed of a material having a higher emissivity than a material constituting the mounting table.
Further, for example, as described in claim 21, the high emissivity precoat film is made of any one of the group consisting of a silicon film, a SiC film, and a SiN film.

According to the film forming apparatus and the film forming method of the present invention, the following excellent operational effects can be exhibited.
Since the surface of the shower head is set so that the emissivity is 0.5 or more by surface treatment, even if an unnecessary adhesion film is deposited on the shower head during film formation, the temperature of the object to be processed The amount of fluctuation can be greatly suppressed.
Therefore, the temperature fluctuation of the object to be processed can be suppressed for each process, so that the film thickness uniformity between the objects to be processed can be improved, and the reproducibility of the film thickness can be kept high.
In particular, according to the invention of claim 10, since the precoat layer is set to a two-layer structure, the amount of heat input for heating the object to be processed can be reduced, and the heating efficiency can be improved accordingly. it can.

In particular , according to the invention according to claim 13 and the claim quoting this , the high emissivity precoat film made of a film type having a higher emissivity than the thin film deposited on the object to be processed, and the upper layer of the high emissivity precoat film Since the precoat layer is formed by the upper layer precoat film formed of the same film type as the thin film, the temperature difference between the mounting table and the object to be processed placed thereon can be reduced, and the mounting is performed. The temperature difference between the central part and the peripheral part of the mounting table can be suppressed, and the mounting table can be prevented from being damaged due to thermal expansion and contraction stress. In addition, the reproducibility of the film forming process can be improved.

Hereinafter, an embodiment of a film forming apparatus and a film forming method according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional configuration diagram showing a film forming apparatus according to the present invention, and FIG. 2 is an enlarged cross-sectional view showing a shower head portion on which an alumite layer is formed. Here, a case where a thin film of a refractory metal such as tungsten or tungsten silicide is formed as an example will be described.
As shown in the figure, this film forming apparatus 2 has a processing container 4 made of aluminum or aluminum alloy, for example, whose inside is substantially circular. In addition to a necessary processing gas, for example, W (CO) ₆ or SiH ₄ which is a raw material gas for film formation, N ₂ , Ar or the like is introduced into the ceiling portion in the processing container 4 by a gas introducing means. A certain shower head unit 6 is provided, and the processing gas is jetted out from the numerous gas jetting holes 10 provided on the gas jetting surface 8 on the lower surface toward the processing space S.

<Dependence of emissivity on wafer temperature>
Next, an experiment for evaluating the dependence of the wafer temperature on the emissivity was performed, and the evaluation result will be described.
FIG. 4 is a graph showing the dependence of the wafer temperature and the wafer temperature change amount on the emissivity. Here, changes in the wafer temperature and the emissivity when a tungsten film was formed on the surface of a large number of wafers in a film forming apparatus having a conventional shower head portion in which an alumite layer was not provided in the shower head portion were examined. The temperature of the mounting table is set to 691 ° C. Moreover, the temperature of the shower head part is set to 45 degreeC. In FIG. 4, the horizontal axis represents the emissivity, the left vertical axis represents the wafer temperature, and the right vertical axis represents the wafer temperature change (the change in wafer temperature relative to the change in emissivity 0.1). ing.

First, as a film that is in direct contact with the lowermost layer of the precoat layer 80, that is, the surface of the mounting table 24, a base precoat film 82 made of the same film type as the thin film formed on the wafer, that is, a W film is formed on the entire surface. ing.
A high emissivity precoat film 84 is formed on the entire surface of the base precoat film 82 via a tungsten nitride film (WN) 82A, which is a nitride film of the material forming the base precoat film 82, at the interface. Yes. The tungsten nitride film 82A functions as a barrier layer. The high emissivity precoat film 84 is formed of a film type to be formed on the wafer, that is, a film type having a higher emissivity than the tungsten film, for example, a silicon film (Si) here. As a material of the high emissivity precoat film 84, it is preferable to select a material having a higher emissivity than the material constituting the mounting table 24, for example, AlN.

Claims (24)

A processing vessel made evacuable;
A mounting table provided in the processing container for mounting an object to be processed;
Heating means for heating the object to be processed;
A shower head provided on the ceiling of the processing vessel so as to face the mounting table and supplying a film forming source gas, and depositing a predetermined thin film on the surface of the object to be processed. In the membrane device,
2. A film forming apparatus, wherein the surface of the shower head is configured to have a radiation rate of 0.5 or more by surface treatment.   The film forming apparatus according to claim 1, wherein the shower head unit is made of aluminum or an aluminum alloy, and an alumite layer formed by the surface treatment is provided on a surface of the shower head unit.   The film forming apparatus according to claim 2, wherein the base material of the shower head portion is a metal according to JIS standard A6061, and the thickness of the anodized layer is 17 µm or more.   The film forming apparatus according to claim 2, wherein the base material of the shower head portion is a metal according to JIS standard A5052, and the thickness of the alumite layer is 28 µm or more.   The film forming apparatus according to claim 1, wherein a resistance heater is built in the mounting table as the heating unit. When depositing a predetermined thin film on the surface of an object to be processed using the film forming apparatus according to claim 1,
A precoat layer forming step of forming a precoat layer on at least the surface of the mounting table by flowing a predetermined gas into the processing container in an empty state where the object to be processed is not carried into the processing container;
A film forming method comprising carrying out the thin film forming step of carrying the object to be processed into the processing container and forming the thin film on the object to be processed after the precoat layer forming step.   The thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is made of the same material as the thin film formed on the surface of the object to be processed. Film forming method.   The film forming method according to claim 6, wherein the thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step is made of the metal silicide.   The thin film is a metal film or a metal-containing film, and the precoat layer in the precoat layer forming step has a two-layer structure of a silicon film and the silicide of the metal formed on the silicon film. The film forming method according to claim 6.   The film forming method according to claim 7, wherein the metal-containing film is made of a nitride, carbide, silicide, or a mixture of two or more substances of the metal.   11. The film forming method according to claim 6, wherein the metal is at least one metal selected from the group consisting of tungsten, titanium, tantalum, hafnium, and zirconium. In the precoat layer that covers the surface of the mounting table on which the object to be processed is mounted in a processing container that can be evacuated to deposit a predetermined thin film on the surface of the object
A high emissivity precoat film made of a film type having a higher emissivity than the thin film;
An upper precoat film formed on the upper layer of the high emissivity precoat film and made of the same film type as the thin film;
A precoat layer comprising: The precoat layer according to claim 12, wherein the high emissivity precoat film is formed of a material having a higher emissivity than a material constituting the mounting table. The precoat layer according to claim 12 or 13, wherein the upper layer precoat film is formed on an upper surface of the mounting table except for a mounting region on which the object to be processed is directly mounted. . The precoat layer according to any one of claims 12 to 14, wherein a base precoat film made of the same film type as the thin film is formed under the upper layer precoat film. The precoat layer according to any one of claims 12 to 15, wherein a nitride film made of a material forming a lower precoat film at the interface is formed at an interface between the precoat films. The precoat layer according to any one of claims 12 to 16, wherein the high emissivity precoat film is made of any one of the group consisting of a silicon film, a SiC film, and a SiN film. The precoat layer according to claim 12, wherein the thin film is made of a metal film or a metal-containing film. The precoat layer according to any one of claims 12 to 18, wherein the metal-containing film is made of one selected from the group consisting of a metal nitride, a carbide, and a silicide that form the metal film. The precoat layer according to claim 19, wherein the metal is at least one metal selected from the group consisting of tungsten, titanium, tantalum, hafnium, and zirconium. In a method for forming a precoat layer that covers the surface of a mounting table on which the object to be processed is mounted in a processing container that can be evacuated so as to deposit a predetermined thin film on the surface of the object
Forming a high emissivity precoat film made of a film type having a higher emissivity than the thin film;
Forming an upper precoat film made of the same film type as the thin film on the upper layer of the high emissivity precoat film;
A method for forming a precoat layer, comprising: The method for forming a precoat layer according to claim 21, wherein the step of forming the upper layer precoat film is performed in a state where a dummy object is placed on the upper surface of the mounting table. 23. The method of forming a precoat layer according to claim 21 or 22, wherein a step of forming a base precoat film made of the same film type as the thin film is performed prior to the step of forming the high emissivity precoat film. Immediately after each step of forming each precoat film,
The method for forming a precoat layer according to any one of claims 21 to 23, wherein a nitriding step of nitriding the surface of the precoat film is performed.

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