JPWO2015162778A1 - Mirrortron sputtering equipment - Google Patents

Abstract

Provided is a mirrortron sputtering apparatus capable of reducing the discharge voltage during sputtering and preventing the occurrence of abnormal discharge and maintaining stable sputtering. The mirrortron sputtering apparatus of the present invention is arranged so as to be opposed to the target at a position on the magnetic field space side of each target at or near the outer peripheral edge of each target arranged in the vacuum vessel. And a pair of target shields having an opening facing the erosion region of each target. Each of the target shields is an outer peripheral edge substantially similar to the outer peripheral edge of the erosion region of each target, and is about 1 to 11 mm or about An opening having an outer peripheral edge located on the outer peripheral side by 3 to 5 mm is provided.

Description

  The present invention relates to a mirrortron sputtering apparatus, and more particularly to a mirrortron sputtering apparatus capable of maintaining stable sputtering.

  Conventionally, for example, a mirrortron (opposite target type) sputtering apparatus as shown in FIG. 9 is used as a sputtering apparatus that meets the demands for increasing the size of a substrate, increasing the speed of thin film formation, and reducing the damage of a thin film during processing. It is known (see Patent Document 1). In the conventional mirrortron sputtering apparatus shown in FIG. 9, a pair of targets 9 are arranged opposite to each other in the vacuum vessel 1, and magnets 12 a for forming a magnetic field space H between the targets 9 and 9. 12b is arranged on the back side of each target 9 so that different magnetic poles face each other, and further, on the side between the targets 9 and 9 so that the substrate 22 to be processed faces the magnetic field space H. It is arranged. In this conventional mirrortron sputtering apparatus, a gas supply pipe 19 for supplying a reactive gas such as oxygen gas or nitrogen gas is provided in the vicinity of the substrate 22, and in the vicinity of the side between the targets 9, 9. A gas supply pipe 20 is provided for supplying an inert gas such as argon gas. In FIG. 9, 14 is a yoke joined to the end of each of the magnets 12a and 12b, 8 is a target holder for supporting each target 9, and 18 is a position on the substrate 22 side of each target holder 8. The partition wall 18 a is an opening formed at a position facing the substrate 22 of the partition wall 18.

  When performing sputtering using such a conventional mirrortron sputtering apparatus, after evacuating the vacuum vessel 1 to make a vacuum, for example, argon gas is supplied from the gas supply pipe 20, and then A voltage is applied to the target 9 from a DC power source (not shown) so that the target 9 is a cathode. Then, the argon gas existing between the targets 9 is ionized into plasma. The plasma generated in this manner sputters the targets 9 and 9 while reciprocating between the targets 9 and 9 while being confined in the magnetic field space H. The sputtered particles jump out of the magnetic field space H, are oxidized by, for example, oxygen gas supplied from the gas supply pipe 19, and adhere and deposit on the surface of the substrate 22. As a result, a thin film is formed on the surface of the substrate 22.

  Further, in such a conventional mirrortron sputtering apparatus, as shown in FIG. 9, the outer peripheral edge of each target 9 and its periphery are covered on the magnetic field space H side of each target 9, for example, made of stainless steel. A target shield (shield cover) 16 made of a flat frame is provided. The target shield 16 has an erosion region (the erosion, that is, a reduction in wall thickness caused by the sputtering, which is sputtered by the plasma in the surface of each target 9 so as not to prevent the sputtering of each target 9 by the plasma. An opening 16a having an outer peripheral edge that faces the area) and coincides with the outer peripheral edge of the erosion area is formed.

  In such a target shield 16, the sputtered particles adhere to and accumulate on the outer portion (non-erosion region) of the erosion region in the surface of each target 9, and abnormal discharge occurs due to this. This is to prevent the adhered particles from peeling off and generating particles.

  The target shield 16 is electrically connected to the wall surface of the vacuum vessel 1 so as to have a ground potential (0 V) (the target shield 16 is electrically connected to the wall surface of the vacuum vessel 1. It may be kept in an electrically floating state by being insulated.

Japanese Patent No. 3505559

  However, in the case of performing sputtering using the conventional mirrortron sputtering apparatus as described above, the discharge voltage increases with time during film formation or abnormal discharge occurs, and the apparatus must be stopped. There were many cases. Further, in the case of performing sputtering using the conventional mirrortron sputtering apparatus as described above, when an image showing plasma in the magnetic field space H is visually observed during film formation, reddish white light is emitted in the image. In many cases, the phenomenon of the plasma moving visually was confirmed.

  As described above, in the conventional mirrortron sputtering apparatus, the discharge voltage often increases with time or abnormal discharge occurs during film formation. There is often a phenomenon of visual movement (in order to maintain stable sputtering, it is desirable that the plasma does not move visually). Therefore, high energy is applied to the substrate during film formation. There have been problems such as that particles are incident and the thin film in the process is damaged, discharge voltage rises or abnormal discharge occurs, and stable sputtering cannot be sustained.

  The present invention has been made paying attention to such problems of the prior art, and lowers the initial discharge voltage during film formation when sputtering is performed using a mirrortron sputtering apparatus. Phenomenon that discharge voltage rises during film formation, phenomenon that abnormal discharge occurs during film formation, phenomenon that plasma existing in magnetic field space moves visually during film formation, and during film formation It is possible to prevent the spatter particles from adhering to the outer peripheral side of the erosion region of the target. As a result, high energy particles are incident on the substrate during film formation, and the thin film in the process is damaged. An object of the present invention is to provide a mirrortron sputtering apparatus capable of maintaining stable sputtering while preventing this.

  In the conventional mirrortron sputtering, a negative potential of about −500 V is applied to each target 9 at the time of film formation, so that particles having high energy equal to the target potential enter the substrate and damage the thin film in the process. I gave it. Also, in conventional mirrortron sputtering, the discharge voltage rises over time during film formation or abnormal discharge occurs, causing high energy particles to enter the substrate and damage the thin film being processed. was there.

  Therefore, the present inventor changed the shape and opening size of the outer peripheral edge (the inner peripheral edge of the frame-like body constituting the target shield) of the target shield in various ways, and various shapes thus changed. Of initial discharge voltage during film formation and increase of discharge voltage during film formation when continuous film formation was performed using a Mirrortron sputtering apparatus equipped with target shields having openings of different sizes Experiments and measurements were carried out to determine whether or not there was any abnormal discharge during film formation, and whether or not there was a phenomenon in which plasma existing in the magnetic field space during film formation moved visually.

  As a result, the inventor opens the opening of the target shield with an outer peripheral edge of a substantially circular or substantially elliptical shape that is substantially similar to the outer peripheral edge of the target erosion region (usually substantially circular or substantially elliptical). When it is configured to have an outer peripheral edge that extends to the outer peripheral side by about 1 to 11 mm (more preferably about 3 to 5 mm) in the radial direction or the long axis direction from the position that coincides with the outer peripheral edge of the erosion region The initial discharge voltage during film formation can be lowered, the discharge voltage can be prevented from rising during film formation, and the occurrence of abnormal discharge during film formation can be suppressed. It is possible to prevent the phenomenon that the plasma existing in the magnetic field space during film formation moves visually, and to suppress the adhesion of sputtered particles to the outer periphery of the erosion region of the target. Becomes way, the results, high-energy particles discovered that will allow sustained stable sputtering while preventing damage a thin film in the process and enters the substrate. As a result, the present inventor has completed the invention of a mirrortron sputtering apparatus provided with the following novel target shield.

  That is, the mirrortron sputtering apparatus according to the present invention includes a vacuum container in which a substrate to be processed is disposed, a pair of targets disposed to face each other at a predetermined interval in the vacuum container, and each of the targets. A pair of magnets arranged so that different magnetic poles face each other at a position on the back side or a side of a face of each target that is at or near the outer peripheral edge of each of the targets, and A mirrortron sputtering apparatus comprising: a pair of target shields, each of which is disposed at a position on the magnetic field space side so as to face the target, and has a pair of target shields each having an opening facing the erosion region of each target. The opening of each target shield is a substantially circular or substantially elliptical airflow in each target surface. An outer peripheral edge having a shape substantially similar to that of the outer peripheral edge of the outer region, the outer peripheral edge being positioned on the outer peripheral side by about 1 to 11 mm in the radial direction or the major axis direction from the outer peripheral edge of the erosion region. It is what is formed to have.

  In addition, the mirrortron sputtering apparatus according to the present invention includes a vacuum container in which a substrate to be processed is disposed, a pair of targets disposed to face each other with a predetermined interval in the vacuum container, and each of the targets A pair of magnets arranged so that different magnetic poles face each other at a position on the back side or a side of a face of each target that is at or near the outer peripheral edge of each of the targets, and A mirrortron sputtering apparatus comprising: a pair of target shields, each of which is disposed at a position on the magnetic field space side so as to face the target, and has a pair of target shields each having an opening facing the erosion region of each target. The opening of each target shield has a substantially circular or substantially elliptical erosion in each target surface. An outer peripheral edge having a shape substantially similar to the outer peripheral edge of the region, and having an outer peripheral edge located on the outer peripheral side by about 3 to 5 mm in the radial direction or the major axis direction from the outer peripheral edge of the erosion region. Is formed.

  In the present invention, the opening facing the erosion region of each target shield is an outer peripheral portion having a shape substantially similar to the outer peripheral portion of the substantially circular or elliptical erosion region in each target surface. The outer peripheral edge of the erosion region is configured to have an outer peripheral edge having a size larger by about 1 to 11 mm in the radial direction or the long axis direction than the outer peripheral edge of the erosion region (so as to extend to the outer peripheral side by about 1 to 11 mm). Therefore, when sputtering is performed using a mirrortron sputtering apparatus, the initial discharge voltage during film formation can be lowered, the discharge voltage increases during film formation, and abnormal discharge occurs during film formation. Phenomenon, a phenomenon in which plasma existing in the magnetic field space moves visually during film formation, and a phenomenon that occurs on the outer periphery side of the erosion region of the target during film formation. Jitter particles it is possible to prevent a phenomenon that adhere. Therefore, according to the present invention, it is possible to prevent an increase in discharge voltage or abnormal discharge while preventing high energy particles from being incident on the substrate during film formation and damaging the thin film being processed. And stable sputtering can be maintained.

  Further, in the present invention, the outer peripheral edge having a shape substantially similar to the outer peripheral edge of the substantially circular or elliptical erosion area in each target surface, the opening facing the erosion area of each target shield. And an outer peripheral edge portion having a size larger by about 3 to 5 mm in the radial direction or the longer axis direction than the outer peripheral edge portion of the erosion region (so as to spread to the outer peripheral side by about 3 to 5 mm) Since it is configured, when performing sputtering using a mirrortron sputtering apparatus, the initial discharge voltage during film formation can be lowered, and the discharge voltage rises during film formation. Phenomenon that abnormal discharge occurs, phenomenon that plasma existing in the magnetic field space moves visually during film formation, and outside of erosion area of target during film formation It is possible to prevent a phenomenon that sputtered particles adhere. Therefore, according to the present invention, it is possible to prevent an increase in discharge voltage or abnormal discharge while preventing high energy particles from being incident on the substrate during film formation and damaging the thin film being processed. And stable sputtering can be maintained.

It is a top view which shows the target shield which concerns on one Embodiment of this invention. Using a conventional mirrortron sputtering apparatus equipped with a target shield having an opening having an outer peripheral edge that coincides with the outer peripheral edge of the erosion region of the target, measurement results of discharge voltage and the like when continuously formed are shown. FIG. According to an embodiment of the present invention, a mirrortron sputtering apparatus including a target shield having an opening having an outer peripheral edge located on the outer peripheral side by a length of 1 mm or more from the outer peripheral edge of the erosion region of the target is used. FIG. 6 is a diagram showing measurement results of discharge voltage and the like when continuous film formation is performed. In accordance with another embodiment of the present invention, a mirrortron sputtering apparatus having a target shield having an opening having an outer peripheral edge located on the outer peripheral side by a length of 11 mm or less from the outer peripheral edge of the erosion region of the target is used. Then, it is a figure which shows the measurement results, such as a discharge voltage when it forms into a continuous film. By using a mirrortron sputtering apparatus having a target shield having an opening having an outer peripheral edge located on the outer peripheral side by a length exceeding 11 mm from the outer peripheral edge of the erosion region of the target according to a comparative example. It is a figure which shows the measurement results, such as a discharge voltage when it forms into a film. It is a figure which shows the state which can be seen when visually observing the plasma in the magnetic field space H in each case when it forms continuously into a film using a plurality of types of mirrortron sputtering apparatuses having different target shield opening sizes. . The figure which shows the adhesion state of the sputter | spatter particle | grains to the peripheral part of the erosion area | region of the target in each case when it forms continuously into a film using several types of mirrortron sputtering apparatuses from which the size of the opening part of a target shield mutually differs It is. The initial discharge voltage, the stability of the discharge voltage, the degree of increase in the discharge voltage, and the state of plasma observation when continuously forming films using multiple types of mirrortron sputtering equipment with different target shield opening sizes It is a figure which shows each measurement result about abnormal discharge and film peeling. It is the schematic which shows the conventional mirrortron sputtering device.

  FIG. 1 is a plan view showing a target shield according to an embodiment of the present invention. In FIG. 1, 31 is a frame-shaped target shield made of, for example, a stainless steel flat plate, 32 is an opening formed inside the target shield 31, and 32 a is an outer peripheral edge of the opening 32 (the target shield 31 is replaced with the target shield 31. It is the inner peripheral edge of the frame-shaped body to constitute.

  In FIG. 1, A is the outer peripheral edge of the target (see 9 in FIG. 9) facing the target shield 31, and B is the outer peripheral edge ( The boundary portion between the erosion region and the non-erosion region).

  As described above, the target shield (see 16 in FIG. 9) in the conventional mirrortron sputtering apparatus has an outer peripheral edge portion of the opening (see 16a in FIG. 9), and the outer peripheral edge portion B (see FIG. 1) of the erosion region. Reference) was configured to match. On the other hand, as shown in FIG. 1, the target shield 31 of the mirrortron sputtering apparatus of this embodiment has a substantially elliptical shape in which the opening 32 is substantially similar to the outer peripheral edge B of the erosion region of the target. The outer periphery of the erosion region extends to the outer peripheral side by about 1 to 11 mm, for example, about 3 to 5 mm in the major axis direction from the position facing and coincident with the outer periphery B of the erosion region (the outer periphery of the erosion region The outer peripheral edge portion 32a is configured to have a size larger by about 1 to 11 mm, more preferably about 3 to 5 mm in the major axis direction than the portion B).

  According to various experiments (to be described later) by the present inventors, when sputtering is performed using this embodiment having the target shield 31 as described above, the initial discharge voltage during film formation is reduced. A phenomenon that discharge voltage rises during film formation, abnormal discharge occurs during film formation, a phenomenon in which plasma existing in a magnetic field space moves visually during film formation, and Prevents spatter particles from adhering to the outer periphery of the target erosion area during film formation, preventing high energy particles from entering the substrate and damaging the thin film during processing. However, it becomes possible to maintain stable sputtering.

Next, a plurality of experiments and measurement results conducted by the inventor regarding the embodiment of the present invention will be described. First, the first experiment conducted by the present inventor will be described. The present inventor, using the formed target shield (conventional target shield) so that the outer peripheral edge of the opening coincides with the outer periphery of the erosion area of the target, Al ₂ O ₃ film (average to the substrate A film having a thickness of 1800 mm was continuously formed, and the discharge voltage during the film formation, the presence or absence of occurrence of abnormal discharge, the state of plasma by visual observation, the degree of adhesion of sputtered particles to the outer periphery of the target, and the like were measured. In this case, as shown in FIG. 7A, the phenomenon that the sputtered particles adhered and deposited on the outer peripheral side of the erosion region of the target was not observed. However, in this case, as shown in FIGS. 2 and 8, the initial discharge voltage was as high as 520 V, the discharge voltage tended to increase with time during film formation, and abnormal discharge also occurred. In this case, as shown in FIG. 6A, the plasma in the magnetic field space H is visually moving and a red-white color is generated (a phenomenon indicating that the plasma is not stable). It was observed. Therefore, from the experiment shown in FIG. 2, the film is continuously formed using a target shield (conventional target shield) formed so that the outer peripheral edge of the opening coincides with the outer peripheral edge of the erosion region of the target. Indicates that the initial discharge voltage during film formation is high, the discharge voltage tends to increase during film formation, abnormal discharge occurs during film formation, and the magnetic field space H during film formation. It was confirmed that the inner plasma was moving visually.

Next, a second experiment conducted by the inventor will be described. The inventor uses a target shield formed on the outer peripheral side of the outer peripheral edge portion of the opening in the long axis direction with respect to the outer peripheral edge portion of the target erosion region by about 1 mm or more, and in this experiment, only 1 mm. The Al ₂ O ₃ film (average film thickness 1800 mm) is continuously formed, the discharge voltage during the film formation, the presence or absence of abnormal discharge, the state of the plasma by visual observation, the adhesion of sputtered particles to the outer periphery of the target The degree was measured. In this experiment, as shown in FIGS. 3 and 8, the initial discharge voltage is 430 V, which is lower than the conventional example, and the discharge voltage does not increase over time during film formation, and abnormal discharge occurs. I didn't. In this experiment, as shown in FIG. 6B, in the observation of the image showing the plasma in the magnetic field space H, the phenomenon that the plasma is moving visually (the phenomenon that the plasma is not stable). ), No red-white coloration, only Ar plasma coloration was observed. Furthermore, in this experiment, as shown in FIG. 7A, a phenomenon in which sputtered particles adhered to the outer peripheral side of the erosion region of the target was not observed. Therefore, from this experiment, when a film was continuously formed using a target shield in which the outer peripheral edge of the opening was formed on the outer peripheral side of the outer peripheral edge of the target erosion region by about 1 mm or more in the major axis direction, The initial discharge voltage during film formation is lowered, the discharge voltage does not increase during film formation, abnormal discharge does not occur during film formation, and the plasma in the magnetic field space H during film formation It was confirmed that no visually moving phenomenon occurred and that sputtered particles did not adhere to the outer peripheral side of the erosion region of the target during film formation.

Next, a third experiment conducted by the inventor will be described. The inventor uses the target shield formed on the outer peripheral side of the outer peripheral edge portion of the opening in the major axis direction to be approximately 11 mm or less than the outer peripheral edge portion of the erosion region of the target. The Al ₂ O ₃ film (average film thickness 1800 mm) is continuously formed, the discharge voltage during the film formation, the presence or absence of abnormal discharge, the state of the plasma by visual observation, the adhesion of sputtered particles to the outer periphery of the target The degree was measured. In this experiment, as shown in FIGS. 4 and 8, the initial discharge voltage is 427 V, which is lower than the conventional example, and the discharge voltage does not increase over time during film formation, and abnormal discharge occurs. I didn't. In this experiment, as shown in FIG. 6B, in the observation of the image showing the plasma in the magnetic field space H, the phenomenon that the plasma is moving visually (the phenomenon that the plasma is not stable). ), No red-white coloration, only Ar plasma coloration was observed. Furthermore, in this experiment, as shown in FIG. 7A, a phenomenon in which sputtered particles adhered to the outer peripheral side of the erosion region of the target was not observed. Therefore, from this experiment, the outer peripheral edge of the opening was continuously formed using a target shield formed on the outer peripheral side by a length of about 11 mm or less in the major axis direction from the outer peripheral edge of the erosion region of the target. When the initial discharge voltage during film formation is lowered, the discharge voltage does not increase during film formation, abnormal discharge does not occur during film formation, and the magnetic field space H during film formation does not occur. It was confirmed that there was no phenomenon that the inside plasma moved visually, and that the sputtered particles did not adhere to the outer peripheral side of the erosion region of the target during film formation.

Next, a fourth experiment conducted by the inventor will be described. The inventor uses a target shield formed on the outer peripheral side of the outer peripheral edge portion of the opening by about 11 mm longer than the outer peripheral edge portion of the erosion region of the target in the major axis direction, for example, 15 mm in this experiment. Then, the Al ₂ O ₃ film (average film thickness 1800 mm) is continuously formed on the substrate, and the discharge voltage during the film formation, the presence or absence of abnormal discharge, the state of the plasma by visual observation, the target periphery of the sputtered particles The degree of adhesion to the part was measured. In this experiment, as shown in FIGS. 5 and 8, the initial discharge voltage is 348V, which is significantly lower than that of the conventional example, and the discharge voltage does not increase over time during film formation. Did not occur. In this experiment, as shown in FIG. 6B, in the observation of the image showing the plasma in the magnetic field space H, the phenomenon that the plasma is moving visually (the phenomenon that the plasma is not stable). ), No red-white coloration, only Ar plasma coloration was observed. However, in this experiment, as shown in FIG. 7B, a phenomenon occurs in which a large amount of sputtered particles adhere to the outer peripheral side of the erosion region of the target and the film formed by the adhesion peels off. I could not. Therefore, from this experiment, the outer peripheral edge of the opening was continuously formed using a target shield formed on the outer peripheral side by a length exceeding the outer peripheral edge of the target erosion region by about 11 mm in the major axis direction. When the initial discharge voltage during film formation is reduced, the discharge voltage does not increase during film formation, abnormal discharge does not occur during film formation, and the magnetic field space during film formation On the other hand, a large amount of sputtered particles adhered to the outer peripheral side of the erosion region of the target during film formation, and the film formed by the adhesion was peeled off. It was confirmed that the phenomenon occurred and continuous film formation was impossible.

  FIG. 8 summarizes the experiments and measurement results described with reference to FIGS. 2 to 5 so that they can be easily compared with each other. From FIG. 8, the initial discharge voltage at the time of film formation is lowered, so that the discharge voltage does not increase during film formation, and abnormal discharge does not occur during film formation. This prevents a phenomenon in which the plasma in the magnetic field space H moves visually, and a large amount of sputter particles adhere to the outer peripheral side of the erosion region of the target during film formation, and the formed film is peeled off. In order to prevent the phenomenon from occurring, it has been found that it is desirable to form the opening portion of the target shield so as to extend to the outer peripheral side by about 1 to 11 mm from the erosion region of the target.

DESCRIPTION OF SYMBOLS 1 Vacuum container 8 Target holder 9 Target 12a, 12b Magnet 16, 31 Target shield 16a, 18a, 32 Opening 18 Partition 19 Gas supply pipe 20 Gas supply pipe 22 Substrate 32a Outer peripheral edge A of target Outer peripheral edge B Perimeter edge H of target surface erosion region Magnetic field space

Claims (2)

A vacuum vessel in which a substrate to be processed is disposed, a pair of targets disposed opposite to each other with a predetermined interval in the vacuum vessel, and a position at or near the outer peripheral edge of each target. A pair of magnets arranged so that different magnetic poles face each other on the back side or side position of the surfaces facing each other, and each target at the position on the magnetic field space side of each target. A mirrortron sputtering apparatus comprising a pair of target shields that are arranged so as to face each other and are made of a frame-like body having an opening that faces the erosion region of each target,
The opening of each target shield is an outer peripheral edge having a shape substantially similar to the outer peripheral edge of the substantially circular or elliptical erosion region in each target surface, and the outer peripheral edge of the erosion region. The mirrortron sputtering apparatus is formed so as to have an outer peripheral edge portion positioned on the outer peripheral side by about 1 to 11 mm in the radial direction or the long axis direction. A vacuum vessel in which a substrate to be processed is disposed, a pair of targets disposed opposite to each other with a predetermined interval in the vacuum vessel, and a position at or near the outer peripheral edge of each target. A pair of magnets arranged so that different magnetic poles face each other on the back side or side position of the surfaces facing each other, and each target at the position on the magnetic field space side of each target. A mirrortron sputtering apparatus comprising a pair of target shields that are arranged so as to face each other and are made of a frame-like body having an opening that faces the erosion region of each target,
The opening of each target shield is an outer peripheral edge having a shape substantially similar to the outer peripheral edge of the substantially circular or elliptical erosion region in each target surface, and the outer peripheral edge of the erosion region. The mirrortron sputtering apparatus is formed so as to have an outer peripheral edge portion positioned on the outer peripheral side by about 3 to 5 mm in the radial direction or the long axis direction.

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