JP2006299370A - Film deposition apparatus, and film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition apparatus and a film deposition method capable of always obtaining a constant film thickness and film deposition rate even in a continuous operation for a long time in a sputter method using a powder target material. <P>SOLUTION: The film deposition apparatus comprises a vacuum tank capable of maintaining vacuum, a substrate holding stand which is located in the vacuum tank to load a substrate thereon, a cathode which is installed facing the substrate holding stand, and turned around the center axis of a face opposing the substrate holding stand while loading a container to hold a powder target material, a power supply to apply the voltage to the cathode, and a gas supply/exhaust means to discharge gas in the vacuum tank while supplying the gas therein. A grounding shield is arranged with an opening part formed between the substrate holding stand and the cathode, and a stirring means to stir the powder target material is provided on a part of the surface on the cathode side of the grounding shield. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film forming apparatus and a film forming method for forming a thin film on a substrate using a powdery target material.

  In recent years, high performance and miniaturization of devices have progressed, and the range of application of the thin film forming process which is one of the elemental technologies has expanded. However, since many thin film formation processes require sophisticated equipment systems such as vacuum technology, cost is often viewed as a problem, and the issue is how to increase productivity and make efficient manufacturing. It has become.

In particular, dielectrics and insulators that have been used in the processing of bulk materials have been increasingly thinned, for example, metals such as silicon dioxide (SiO ₂ ), titanium oxide (TiO ₂ ), and magnesium oxide (MgO). Thin films of oxides or nitrides such as silicon nitride (SiN) have been used. However, there are still problems in productivity. This is mainly because a sintered body is used as the target material, so that the sputtering rate is small and the film formation rate cannot be sufficiently increased.

However, in recent years, it has been reported that a granular material is used instead of the solid material that has been used so far, for example, there is an invention described in Patent Document 1. According to Patent Document 1, by devising the form of the material held in the vacuum chamber, the material life is extended, the operation rate is improved, and the productivity is improved. In particular, in the case of a solid target, the problem of reducing the operating rate by opening the inside of the vacuum chamber to the atmosphere is improved.
Japanese Patent Laid-Open No. 10-18029

  However, in the invention described in Patent Document 1, when the sputter film formation is performed using the powdery material, the following problems occur.

  That is, the powdery material has a property that it easily aggregates due to the force acting between the particles, and these particles collected as the target material already tend to aggregate. Here, when the discharge of plasma or the like is confronted, the agglomeration further proceeds due to the influence of the generated heat and the like, and the density of the target material is increased.

  Specifically, when ions from the plasma collide with the powder particles that are the target material, heat is generated thereby increasing the surface temperature of the target. Unlike bulk materials, in the case of powders, there are voids between the particles, so the thermal conductivity is very poor. Therefore, the powder particles in the vicinity of the surface of the target material are heated rapidly, and the aggregation of the powder particles is accelerated. Aggregation of powders due to temperature rise proceeds to welding if left untreated, and no longer forms powders.

  As described above, the thermal conductivity of the powder target material is poor, and the target temperature rise and powder aggregation proceed near the surface, so that the internal powder state is not significantly changed. That is, agglomeration proceeds only on the surface of the target material, the density increases, and welding and solidification occur. As a result, in this state, there arises a problem that a high film formation rate that is a characteristic of the powder cannot be obtained.

  As described above, when using a powdery target material, in the initial state where the powder is not agglomerated, the bulk density of the powder is small and the film formation rate by sputtering is high. When the temperature of the surface of the target material rises due to exposure to the powder and the agglomeration of the powder proceeds, the sputtering rate on the surface of the target material decreases and the film formation rate decreases. In other words, if the surface of the same target material is continuously discharged, the degree of powder aggregation changes over time, the film formation rate also decreases over time, and a stable process cannot be realized. It is doing.

  Accordingly, since the target material surface exposed to the sputter discharge is agglomerated immediately, a large amount of film forming treatment cannot be performed using the same target surface, and at the same time, a separately prepared material cannot be used for the same reason.

  The present invention solves the above-described conventional problems, and a film forming apparatus and a film forming method capable of obtaining a stable film thickness and a high film forming rate even with continuous operation for a long time. The purpose is to provide.

  In order to achieve the above object, a film forming apparatus of the present invention includes a vacuum chamber capable of maintaining a vacuum, a substrate holding table in the vacuum chamber on which a substrate is placed, and a substrate holding table. A cathode that is installed and holds a powdery target material and rotates about the central axis of the surface facing the substrate holder, a power source that applies a voltage to the cathode, and a vacuum chamber In a film forming apparatus comprising gas supply / exhaust means for exhausting gas while supplying a gas, an earth shield is provided with an opening between the substrate holding base and the cathode, and a part of the surface of the earth shield on the cathode side Can be solved by providing a stirring means for stirring the powdery target material.

  At this time, it is preferable to process the substrate while supplying the same kind of powder material as the target material to the stirring means.

  The average particle size of the powdery target material is more preferably 50 nm or more and less than 10 μm.

  Furthermore, in the film forming method of the present invention, a container for holding a powdery target material is placed by evacuating while supplying gas into the vacuum chamber, generating plasma while controlling the inside of the vacuum chamber to a predetermined pressure. A film forming method for processing a substrate placed on a substrate holding table facing the cathode by rotating the cathode about the central axis of the surface facing the substrate holding table while applying a voltage to the cathode; The powdery target material has a first region that is exposed to plasma and a second region that is not exposed through an earth shield having an opening disposed between the substrate holder and the cathode. By stirring the powdery target material, the problem can be solved by performing film formation on the substrate while making the bulk density of the target material substantially the same in the first region and the second region.

  At this time, it is preferable to process the substrate while supplying the same kind of powder material as the target material to the stirring means.

  The average particle size of the powdery target material is more preferably 50 nm or more and less than 10 μm.

  As described above, according to the present invention, since a stable film formation rate can be ensured with a uniform film thickness over a long period of time, a film formation apparatus and a film formation method with high productivity can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a first embodiment of the present invention.

A container 3 containing a powder target material 2 is disposed in the vacuum chamber 1 and a substrate 4 is disposed immediately above the container 3. A shutter 5 is disposed between the substrate 4 and the target. Silicon dioxide (SiO ₂ ) powder was used for the target material 2 and the container 3 was made of quartz (SiO). The container 3 is disposed on a copper electrode 6 having a rotating function, and a high frequency power source 8 is connected to the electrode 6 through a matching circuit 7, and at the same time, a water channel is cut to circulate cooling water. Thus, cooling is performed against the generation of heat by the plasma.

  FIG. 2 is a detailed view of the cathode including the target material 2, the container 3 and the electrode 6, FIG. 2 (1) is a top view of the cathode, and FIG. 2 (2) is a side view.

  In the figure, the depth of the container 3 is 10 mm, the diameter is 400 mm, and a powdery target material is spread over here. The container 3 is arrange | positioned on the electrode 6 which has an area more than equivalent. In addition, an earth shield cover 10 is installed on the upper part of the target material 2 so as to leave a part of the target material and cover the whole, and is grounded to the ground. The space | interval of the space | gap between the target material surface and this covered metal plate was 2 mm.

  When this gap becomes large, the plasma discharge is circulated and it becomes difficult to isolate the target from the plasma. Further, a magnetron magnet 11 made of a plurality of permanent magnets is arranged on the back surface of the electrode 6 in the region where the target surface is exposed, and is arranged so as to form a magnetic circuit closed with the magnet on the exposed target surface. did. Although the exposed surface of the target is formed by the opening shape of the earth shield plate, it has a circular shape with a diameter of 160 mm. This is to stabilize the plasma discharge. A mechanism 12 for stirring the agglomerated powder by mechanical contact with the surface of the target material is provided on a part of the back surface of the earth shield cover.

  FIG. 3 shows details of a mechanical component (stirring means) for separating the agglomerated powder.

  In the figure, the component is a comb-like component 14 in which a plurality of needle-like components 13 having a length of 7 mm and a diameter of about 0.5 mm are arranged. In addition, there are a plurality of component parts 14 in which the arrangement positions of the needle-like parts are changed, and these are arranged in series. The interval between each of the needle-like parts was 5 mm. If the interval is too wide, the stirring effect cannot be obtained, but if it is too small, the powder is clogged between the needle-like parts and the stirring effect cannot be exhibited. Specifically, when the distance between the needle-like parts 13 becomes narrower by 2 mm in the length of the needle-like parts 13 entering the target material, that is, 2 mm in the case of this embodiment, two adjacent ones. When the target material is clogged, the cross section formed by these needle-shaped parts will function as a united part with two adjacent needle-shaped parts and the target material clogged between them. Thus, the surface shape of the target material is roughened.

  From the above view, the distance between the needle-like parts 13 is preferably about 2 to 3 times the distance of the needle-like parts 13 entering the target material. 2 to 6 mm is preferable. In the case of the present embodiment, as shown in FIG. 3, the interval between the needle-like parts is 5 mm, and a stirring effect is exhibited by placing a plurality of those whose arrangement positions are changed.

  In addition, the length of the needle-shaped part was set so that the part was about 5 mm inside the target material, and the total length was 7 mm. This is because the target surface is agglomerated and solidified to a depth of about 1 mm at most, but the material is consumed and reduced as the film formation proceeds. For this reason, since the position of the target material is lowered, the needle-like component needs to have a certain length as a whole. Here, since the depth is 5 mm, it is possible to cope with the reduction of the target up to 4 mm.

  Now, an experiment of a film forming process was performed using the apparatus obtained by such a configuration. Therefore, the operation procedure of the film forming process of this embodiment will be described below.

First, the inside of the vacuum chamber 1 was evacuated to about 10 ⁻⁵ Pa by a vacuum pump (not shown), and then argon gas (Ar gas) was introduced to adjust the pressure to about 0.2 Pa. The rotational speed of the target material container is 2r. p. h.

  The substrate 4 is loaded from the substrate transfer chamber 20 adjacent to the vacuum chamber 1. After loading the substrate 4, high frequency power of 13.56 MHz is applied to the electrode 6 with the shutter 5 closed to generate plasma in the vacuum chamber 1. At this time, the power applied to the electrode 6 is 3 kW. The supplied target material powder material has an average particle size of 500 μm and a bulk density of 0.5, and the substrate is used every 30 minutes when the stirring mechanism 12 is used and when it is not used in the conventional example. Was evaluated for changes in film thickness over time.

  The result is shown in FIG. As shown in the figure, in the present embodiment, when the stirring mechanism 12 is provided in the target material 2, the target material can be prevented from aggregating and solidifying, so that the sputtering rate of the target does not change. A stable film formation rate can be maintained.

  On the other hand, in the conventional example, the target material exposed to the sputter discharge is agglomerated and solidified. As a result, the film formation rate is lowered, and the resulting silicon dioxide film thickness is reduced. That is, a stable process state cannot be obtained. The bulk density of the powder material on the target surface when the process was carried out under the same conditions of the present embodiment was evaluated. The results are shown in FIG.

  As shown in the figure, when the stirring mechanism 12 is not provided, the bulk density of the powder on the target surface increases with the progress of continuous sputtering discharge, indicating that agglomeration is progressing. On the other hand, when the stirring mechanism 12 is arranged, there is no change in the bulk density. Although the target surface agglomerates once due to the discharge of the sputtering, the agitation mechanism 12 immediately functions to release the agglomerated state. Further, since the internal powder that is not exposed to the discharge is put out on the surface by the stirring mechanism 12, the agglomerated powder does not reach a solidified state as a result. Therefore, a stable process can be obtained by reducing the bulk density by the stirring mechanism 12.

(Embodiment 2)
Next, the implementation results when the average particle diameter and the bulk density conditions of the target material 2 are changed will be described. The used apparatus is the same as the apparatus shown in FIGS. 1 to 3, and the same reference numerals are used.

  The average particle diameter of the target material 2 was 5.0 μm, and the bulk density thereof was 0.4. Using these materials, film formation experiments by continuous discharge were performed under the condition of the presence or absence of the stirring mechanism 12, and the film thickness stability was evaluated. The result is shown in FIG.

  As shown in the figure, in this embodiment, when the target material 2 is provided with a stirring mechanism, the target material can be prevented from aggregating and solidifying, so that the sputtering rate of the target does not change and is stable. The film forming rate can be maintained. In the case of the present embodiment, the film thickness is lower than that in the case of the first embodiment.

  This is because when the average particle size of the powder is increased, the sputtering rate is decreased accordingly, and the film formation rate is decreased. On the other hand, in the conventional example, the target material exposed to the sputter discharge is gradually aggregated and solidified. As a result, the film formation rate is lowered, and the resulting silicon dioxide film thickness is reduced. That is, a stable process state cannot be obtained. In this case as well, the bulk density of the powder material on the target surface was evaluated in the same process.

  The results are shown in FIG. Compared to Embodiment 1, the bulk density is large when the average particle size is large. This is because each particle is a substance having a high density, and when the size of the particle is large, the bulk density is also increased. These powders also have increased bulk density due to plasma discharge and increased bulk density. On the other hand, when the stirring mechanism 12 is arranged, there is no change in the bulk density. This is because the target surface aggregates once by sputtering discharge as in the first embodiment, but functions so as to immediately release the aggregated state by the stirring mechanism 12.

  Further, since the internal powder that has not been exposed to the discharge is put out on the surface by the stirring mechanism 12, the agglomerated powder does not reach a solidified state as a result. Therefore, a stable process can be obtained by reducing the bulk density by the stirring mechanism 12.

(Embodiment 3)
Next, a film formation experiment by continuous discharge was performed under the condition of the presence or absence of the stirring mechanism 12 when the average particle size of the powder of the target material 2 was 50 nm and the bulk density was 0.2. The results are shown in FIG.

  When the target stirring mechanism 12 is provided, the target material can be prevented from aggregating and solidifying, so that the sputtering rate of the target does not change and a stable film formation rate can be maintained. In the case of the present embodiment, the film thickness becomes larger than that in the case of the first embodiment. This is because when the average particle size of the powder is reduced, the sputtering rate is increased accordingly, and the film formation rate is increased. On the other hand, in the conventional example, the target material exposed to the sputter discharge is gradually aggregated and solidified. As a result, the film formation rate is lowered, and the resulting silicon dioxide film thickness is reduced. That is, a stable process state cannot be obtained. When the average particle diameter of the powder is small, the aggregation tends to proceed easily, so that the rate of fluctuation of the film thickness over time in the conventional example also tends to increase. Therefore, the effect of the present invention is greater as the average particle size of the powder is smaller.

  Similarly, in this case as well, the bulk density of the powder material on the target surface was evaluated in the same process.

  The results are shown in FIG. Compared to Embodiment 1, the bulk density is large when the average particle size is large. This is because each particle is a substance having a high density, and when the size of the particle is large, the bulk density is also increased. These powders also have increased bulk density due to plasma discharge and increased bulk density. On the other hand, when the stirring mechanism 12 is arranged, there is no change in the bulk density.

  The same examination was further conducted on materials having different average particle diameters.

  As a result, it has been found that 50 nm to 10 μm including the above embodiment is suitable as a range of an appropriate average particle diameter of the powder. This is because when the average particle size of the powder is smaller than 50 nm, the behavior of the powder in the vacuum chamber adheres to each part such as a stirring mechanism and the original function of making the bulk density constant cannot be exhibited. On the other hand, when the average particle diameter of the powder is 10 μm, the sputtering rate of the target material itself is small and the practicality of using the powder material is small.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described.

  FIG. 10 shows an outline of the apparatus used in this embodiment. In the same figure, the same reference numerals are assigned to the same functions as those in the first embodiment.

  10, the target arrangement, the substrate, the gas introduction system, and the cathode configuration for generating plasma discharge are the same as those in FIG. However, the supply part 21 of the powder material which is a target material was newly provided in the part separated from the opening area | region of the earth shield board. The material supply mechanism unit 21 is a mechanism that supplies the material 3 at a constant rate onto the surface of the target material 2 spread on the container 3. The situation of the embodiment using this apparatus will be described below.

The inside of the vacuum chamber 1 was evacuated to about 10 ⁻⁵ Pa by a vacuum pump (not shown), and then argon gas (Ar gas) was introduced to adjust the pressure to 0.2 Pa. The rotation speed of the target material container is 2 r. p. h.

  The substrate 4 is loaded from the substrate transfer chamber 20 adjacent to the vacuum chamber 1. After loading the substrate 4, high frequency power of 13.56 MHz is applied to the electrode 6 with the shutter 5 closed to generate plasma in the vacuum chamber 1. At this time, the power applied to the electrode 6 is 3 kW.

  The target powder material 2 contained in the container has an average particle size of 0.5 μm and a bulk density of 0.5, which is the same as in the first embodiment. Immediately after the start of discharge, the material supply mechanism was operated to supply the material at a rate of 1 g / 4 min. When the material supply mechanism 21 was used and when it was not used in the conventional example, the substrate was introduced every 30 minutes, and the change with time of the film thickness was evaluated.

  The result is shown in FIG. As shown in the figure, in the present embodiment, when the target material 2 supply mechanism is operated and the material is supplied, even if the target material 2 aggregates due to discharge, a new initial bulk density is formed on the surface. Since the material which has is supplied, the surface state is stabilized. As a result, the sputtering rate on the target surface does not change, and a stable film formation rate can be maintained.

  On the other hand, in the conventional example, the target material exposed to the sputter discharge is agglomerated and solidified. As a result, the film formation rate is lowered, and the resulting silicon dioxide film thickness is reduced. That is, a stable process state cannot be obtained. Also in the present invention, a stable process can be obtained by supplying a material having a constant bulk density immediately before discharge.

  The film forming apparatus and the film forming method of the present invention have an effect that a stable film forming rate can be obtained over a long period of time, and can be applied to applications in the field of thin film device formation and surface treatment.

Schematic of a film forming apparatus according to Embodiment 1 of the present invention (1) Top view of the cathode in the film forming apparatus according to Embodiment 1 of the present invention (2) Side view of the cathode of the film forming apparatus according to Embodiment 1 of the present invention (1) Top view of components that stir the surface of the target material in the film forming apparatus according to Embodiment 1 of the present invention. (2) Surface of the target material in the film forming apparatus according to Embodiment 1 of the present invention. Side view of components that stir The figure which shows the time-dependent tendency of the film thickness of the film-forming implemented in 1st Embodiment. The figure which shows the time-dependent state of the bulk density of the target material in Embodiment 1 of this invention The figure which shows the time-dependent state of the film thickness of the film-forming in Embodiment 2 of this invention The figure which shows the time-dependent state of the bulk density of the target material in Embodiment 2 of this invention The figure which shows the time-dependent state of the film thickness of the film-forming in Embodiment 3 of this invention The figure which shows the time-dependent state of the bulk density of the target material in Embodiment 3 of this invention Schematic of the film forming apparatus in Embodiment 4 of the present invention The figure which shows the time-dependent state of the film thickness of the film-forming in Embodiment 4 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum chamber 2 Target material 3 Container 4 Board | substrate 5 Shutter 6 Electrode 7 Matching circuit 8 High frequency power supply 9 Argon gas 10 Earth shield board 11 Magnetron magnet 12 Agitation mechanism 13 Needle-shaped part 14 Material stirring board 20 Substrate conveyance room 21 Material supply mechanism

Claims (6)

A vacuum chamber capable of maintaining a vacuum, a substrate holding table in the vacuum chamber on which a substrate is placed, and a container that holds the powdery target material placed on the substrate holding table. A film forming apparatus comprising: a cathode that rotates about a central axis of a surface facing the substrate holder; a power source that applies a voltage to the cathode; and a gas supply / exhaust unit that exhausts gas while supplying the gas into the vacuum chamber , An earth shield having an opening is disposed between the substrate holder and the cathode, and a stirring means for stirring the powdery target material is provided on a part of the cathode side surface of the earth shield. A film forming apparatus characterized by the above. The film forming apparatus according to claim 1, wherein the substrate is processed while supplying the same kind of powder material as the target material to the stirring unit. 3. The film forming apparatus according to claim 1, wherein the average particle size of the powdery target material is 50 nm or more and less than 10 μm. While supplying gas into the vacuum chamber, exhausting the gas, generating plasma while controlling the inside of the vacuum chamber to a predetermined pressure, and applying a voltage to the cathode on which the container holding the powdery target material is applied, the cathode Is a film forming method for processing a substrate placed on a substrate holding table opposite to a cathode, the powdery target material being a substrate holding table and a substrate holding table. Having a first region exposed to plasma and a second region not exposed through an earth shield having an opening disposed between the cathode and stirring the powdery target material in the second region The film formation method is characterized in that the substrate is formed while the bulk density of the target material is substantially the same in the first region and the second region. The film forming method according to claim 4, wherein the substrate is processed while supplying the same kind of powder material as the target material. 6. The film forming method according to claim 4, wherein the average particle size of the powdery target material is 50 nm or more and less than 10 μm.

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