JP2005097647A - Film deposition method and sputtering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition method and a sputtering system capable of improving the film quality and uniformity in film thickness of a film deposited on a substrate. <P>SOLUTION: Regarding the sputtering system where a metallic target material 15b is collided with argon ions in a vacuum chamber 11, metallic clusters emitted from the metallic target material 15b are deposited on a silicon wafer 50 to deposit a metallic film, a planar target 13 ionizing the surfaces of the metallic clusters emitted from the metallic target material 15b to an optional direction, a collimator 23 allowing only the metallic clusters 40a to 40c emitted from the metallic target material 15b and progressing to a specified direction to pass and capturing the metallic clusters progressing to the other directions; and a pair of electrode plates 25 forming an electric field E in a direction crossed with the specified direction on a space 31 on the progressing passage of the metallic clusters 40a to 40c are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a film forming method and a sputtering apparatus for forming a film by causing a predetermined ion to collide with a target in a vacuum chamber and depositing particles emitted from the target on a substrate.

  Conventionally, in a semiconductor device manufacturing process, a sputtering apparatus has been used as a film forming apparatus for forming an electrode or a metal film for wiring on a silicon wafer (see, for example, Patent Documents 1 and 2). This type of sputtering apparatus includes a vacuum chamber capable of maintaining a vacuum state, a metal target disposed in the vacuum chamber, a substrate holder disposed to face the metal target in the vacuum chamber, The vacuum chamber includes a collimator disposed between the substrate holder and the metal target.

Among these, the collimator is a device that filters metal particles (hereinafter referred to as metal clusters) emitted from a metal target in an arbitrary direction according to the traveling direction. Specifically, this collimator passes only the vertical component of the metal cluster that is emitted from the metal target by collision of argon ions (Ar ⁺ ) and the like and enters the surface of the collimator at a substantially perpendicular incident angle, The oblique component of the metal cluster that entered at an incident angle of is captured.

In the conventional sputtering apparatus, as described in Patent Document 1 and the like, the collimator is disposed between the metal target and the substrate holder so as to be parallel to both the substrate holder and the metal target. Has been. With such a configuration, only the vertical component of the metal cluster emitted from the metal target was deposited on the silicon wafer, thereby forming a metal film.
Japanese Patent Laid-Open No. 10-92767 JP 2001-303247 A

  By the way, according to the above-described conventional sputtering apparatus, only the vertical components of the metal clusters emitted from the metal target are selected, and only the selected metal clusters are deposited on the silicon wafer to form a metal film. It was. Thereby, the coverage characteristic of the metal film can be improved, and for example, the metal film can be formed with a sufficient film thickness with respect to the bottom of the connection hole having a large aspect ratio.

However, the metal clusters released from the target by collision of argon ions or the like are usually particles in which 10 to 10 ³ metal atoms are aggregated, and the size (mass) of the metal clusters appears as a normal distribution. There are various variations.
For this reason, in the sputtering apparatus of the conventional example, a metal having an abnormal size (mass) corresponding to the tail of the normal distribution mixed with a normal size (mass) metal cluster corresponding to the center of the normal distribution. There was a problem that the clusters were also deposited on the silicon wafer. If a metal cluster having an abnormal size (mass) corresponding to the tail of such a normal distribution is included in the metal film on the silicon wafer, the uniformity of the film thickness and film quality of the metal film is lowered. There is a risk that.

  Accordingly, the present invention has been made to solve such problems, and an object thereof is to provide a film forming method and a sputtering apparatus capable of improving the film quality and film thickness uniformity of a film formed on a substrate. .

  In order to solve the above-described problem, according to the film forming method of the present invention, a film is formed by causing predetermined ions to collide with a target in a vacuum chamber and depositing particles emitted from the target on the substrate. In the film forming method, the particles emitted from the target and traveling in a specific direction are sorted according to their masses, and the particles having a desired mass among the sorted particles are collected and deposited on the substrate. It is characterized by this.

Here, the predetermined ions are, for example, argon ions. Moreover, a target is metal targets, such as aluminum or tungsten, for example. Particles emitted from the metal target by the collision of the argon ions or the like (metallic clusters) is a collection of normal 10 to 10 ^three metal atoms are assembled into three-dimensional, the size (mass) of the metal clusters Vary.

According to the film forming method of the present invention, only particles having substantially the same mass are collected and deposited on the substrate to form a film, so that the film quality and film thickness uniformity of this film can be improved.
A first sputtering apparatus according to the present invention is a sputtering apparatus that forms a film by colliding predetermined ions with a target in a vacuum chamber and depositing particles emitted from the target on a substrate. A particle sorting means for passing only the particles that are emitted from and traveling in a specific direction and capturing the particles traveling in the other direction; and a space in the chamber through which the particles sorted by the particle sorting means pass next Electric field forming means for forming an electric field in a direction intersecting with the specific direction, and particle ionizing means for ionizing the surface of the particles before the particles reach the space where the electric field is formed by the electric field forming means, It is characterized by comprising.

  According to the first sputtering apparatus of the present invention, the particles whose surfaces are ionized by the particle ionization means contain more atoms that are not ionized as the size (mass) of the particles increases. The larger the particle size (mass), the smaller the amount of charge per unit mass. Therefore, by applying an electric field in a direction crossing the specific direction to the particles emitted from the target and traveling in the specific direction, the traveling direction can be changed according to the size (mass). Sort by size (mass). As a result, only particles having substantially the same mass can be collected and deposited on the substrate to form a film, so that the film quality and uniformity of the film can be improved.

  A second sputtering apparatus according to the present invention is a sputtering apparatus that forms a film by colliding predetermined ions with a target in a vacuum chamber and depositing particles emitted from the target on a substrate. A particle sorting means for passing only the particles that are emitted from and traveling in a specific direction and capturing the particles traveling in the other direction; and a space in the chamber through which the particles sorted by the particle sorting means pass next Magnetic field forming means for forming a magnetic field in a direction intersecting with the specific direction, particle ionizing means for ionizing the surface of the particles before the particles reach the space where the magnetic field is formed by the magnetic field forming means, It is characterized by comprising.

  According to the second sputtering apparatus of the present invention, by applying a magnetic field in a direction intersecting with the specific direction to particles emitted from the target and traveling in the specific direction, the traveling direction is determined according to the size (mass). The particles can be selected and sorted according to their size (mass). As a result, only particles having substantially the same mass can be collected and deposited on the substrate to form a film, so that the film quality and uniformity of the film can be improved.

The third sputtering apparatus according to the present invention is characterized in that, in the first and second sputtering apparatuses described above, the direction intersecting with the specific direction is a direction orthogonal to the specific direction.
According to the third sputtering apparatus according to the present invention, in the first and second sputtering apparatuses described above, the force in the direction orthogonal to the specific direction can be most efficiently transmitted to the particles traveling in the specific direction. The traveling direction of the particles can be efficiently changed according to the size (mass).

Hereinafter, a film forming method and a sputtering apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram illustrating a configuration example of a sputtering apparatus 100 according to an embodiment of the present invention. The sputtering apparatus 100 is an apparatus for forming a metal film by causing argon ions or the like to collide with a metal target material in a vacuum chamber and depositing metal clusters released from the metal target material on a silicon wafer. As shown in FIG. 1, the sputtering apparatus 100 includes a vacuum chamber 11, a matching box 13, a planar target 15, a high frequency power source 21, a collimator 23, a pair of electrode plates 25, a substrate holder 27, and the like. Has been.

  Among these, the vacuum chamber 11 is a film forming chamber capable of maintaining a vacuum state of about 0.1 to 1.0 [Pa], for example. The vacuum chamber 11 is connected to a load lock chamber (not shown), a gas supply system, a gas exhaust system, and the like. When forming a metal film on a silicon wafer, argon (Ar) gas is supplied to the inside of the sealed vacuum chamber 11 through a gas supply system.

  Further, as shown in FIG. 1, the matching box 13 is attached to the inside of the vacuum chamber 11. The matching box 13 is connected to a high-frequency power source, and applies a high-frequency voltage to the planar target 15 while controlling its value. Further, the planar target 15 is attached to the inside of the vacuum chamber 11, and is composed of a magnet 15a and a metal target material 15b attached on the magnet 15a. The metal target material 15b is made of a metal material such as aluminum or tungsten.

When a high frequency voltage is applied from the matching box 13 to the planar target 15, electrons that have jumped out of the planar target 15 are trapped near the surface of the planar target 15 by the magnetic lines 17, and high density is formed near the surface of the planar target 15. The plasma 19 is formed. The metal cluster emitted in an arbitrary direction by the collision of argon ions is ionized in the vicinity of the surface (the surface and the vicinity thereof) by the plasma 19. In this embodiment, for example, it is assumed that the metal target material 15 is made of aluminum, and a cluster made of aluminum is ionized to Al ⁺ by this plasma.

  Further, the collimator 23 shown in FIG. 1 is attached at a position facing the metal target material 15 b inside the vacuum chamber 11. The collimator 23 passes only the vertical component of the metal cluster that is emitted from the metal target material 15b and enters the entrance of the collimator 23 at a substantially perpendicular incident angle, and passes through the metal cluster that enters at an oblique incident angle. It captures diagonal components. The metal cluster whose surface is ionized by the plasma 19 enters the collimator 19 from its entrance. Of the metal clusters that enter the collimator 19, only the vertical component passes through the interior of the collimator 19, exits the emission port, and proceeds to the space 31 sandwiched between the electrode plates 25.

  As shown in FIG. 1, the electrode plate 25 includes a positive (+) electrode plate 25a and a negative (−) electrode plate 25b. For example, the electrode plate 25 is attached to the inside of the vacuum chamber 11 so as to sandwich a space 31 at a position facing the metal target material 15b across the collimator 23 from both sides. The voltage value between the electrode plates 25a and 25b can be set arbitrarily.

By the way, the number of atoms constituting the metal cluster, that is, the size (mass) of the cluster is different from each other in many metal clusters released from the metal target material by collision of argon ions or the like. This type of metal cluster is usually an aggregate in which 10 to 10 ³ metal atoms are gathered in a three-dimensional manner, and the size (mass) of the metal cluster varies, for example, as shown in a normal distribution. .

  FIG. 3 is a diagram illustrating an example of variations in the size (mass) of metal clusters. In FIG. 3, the horizontal axis indicates the size (mass) of the metal clusters, and the vertical axis indicates the distribution ratio of the metal clusters. In FIG. 3, for example, a metal cluster 40b is a metal cluster having a size (mass) within an average value ± 3σ. Further, a metal cluster 40a having a size (mass) smaller than the average value −3σ is referred to as a metal cluster 40c, and a metal cluster 40c having a size (mass) larger than the average value + 3σ. These metal clusters 40a to 40c proceed to a space 31 sandwiched between the electrode plates 25a and 25b, as shown in FIG. 2, with the vicinity of the surface thereof ionized by the plasma 19 (see FIG. 1).

Here, the larger the size (mass) of the metal clusters 40a to 40c, the greater the number of non-ionized atoms contained therein, and the amount of charge per unit mass of the metal clusters 40a to 40c is Usually, the larger the mass, the smaller the tendency.
Specifically, the mass of metal clusters 40a and _{M a,} a mass of metal clusters 40b and _{M b,} the mass of metal clusters 40c and _{M c.} Further, the amount of charge possessed by the metal clusters 40a and _{Q a.} The amount of charge possessed by the metal cluster 40b and _{Q b,} the amount of charge possessed by the metal clusters 40c and _{Q c.} At this time, the charge amount Q / M per unit mass of the metal cluster 40a~40c _is satisfied the relationship of _{(Q c / M c) <} (Q b / M b) <(Q a / M a). A metal cluster having a larger charge amount Q / M per unit mass is more susceptible to an electric field.

Therefore, as shown in FIG. 2, the traveling direction of the metal cluster 40a with a small size (mass) is greatly bent toward the (−) side by the electric field E, and the traveling direction of the metal cluster 40c with a large size (mass) It doesn't turn very much. Thereby, metal cluster 40a-40b can be sorted according to the size (mass).
As shown in FIG. 2, in the sputtering apparatus 100, the substrate holder 27 is disposed at the tip of the traveling direction bent by the electric field E of the metal cluster 40 b whose size (mass) is within the range of the average value ± 3σ. . The inclination of the substrate holder 27 is adjusted so that the traveling direction of the metal cluster 40b after being bent by the electric field E is orthogonal to the surface of the silicon wafer 50 disposed on the substrate holder 27. . Thereby, the metal cluster 40 b is deposited on the silicon wafer 50 from a direction perpendicular to the surface of the silicon wafer 50. Further, most of the abnormally large (mass) metal clusters 40 a and 40 c deviate from the substrate holder 27, so that they are hardly deposited on the silicon wafer 50.

As described above, according to the sputtering apparatus 100 according to the present invention, the metal clusters 40a to 40c whose surfaces are ionized by the plasma 19 include metal ions that are not ionized in the interior as the size (mass) increases. Since many are included, the larger the mass of the metal cluster, the smaller the amount of charge per unit mass.
Therefore, by applying an electric field E in a direction intersecting with the specific direction to the metal clusters 40a to 40c emitted from the metal target material 15b and proceeding in the specific direction, the traveling direction of these metal clusters 40a to 40c can be set to the magnitude (mass). ) And the metal clusters 40a to 40c can be sorted according to their size (mass). Thus, only the metal clusters 40b having substantially the same mass can be collected and deposited on the silicon wafer 50 to form a metal film, so that the film quality and film thickness uniformity of the metal film can be improved.

  In this embodiment, the vacuum chamber 11 corresponds to the chamber of the present invention, and the metal target material 15b corresponds to the target of the present invention. Further, argon ions colliding with the metal target material 15 correspond to predetermined ions of the present invention, and particles traveling in a specific direction correspond to the metal clusters 40a to 40b of the present invention. Further, the silicon wafer 50 is deposited on the substrate of the present invention, and the metal film corresponds to the film of the present invention. Further, the collimator 23 corresponds to the particle sorting means of the present invention, and the pair of electrode plates 25 corresponds to the electric field forming means of the present invention. The planar target 15 corresponds to the particle ionization means of the present invention, and the sputtering apparatus 100 corresponds to the sputtering apparatus of the present invention.

  In the present embodiment, the case has been described in which an electric field E orthogonal to the specific direction is applied to the metal clusters 40a to 40c traveling in the specific direction, and the traveling directions are bent in different directions. However, as shown in FIG. 4, a magnetic field B that is orthogonal to the specific direction may be applied to these metal clusters 40 a to 40 c instead of the electric field E that is orthogonal to the specific direction. Even in this case, the metal clusters 40a to 40b can be sorted by size (mass) as in the above embodiment. The magnetic field B may be generated by a permanent magnet (not shown), for example.

The conceptual diagram which shows the structural example of the sputtering device 100 which concerns on embodiment. The figure which shows an example of the metal cluster 40a-40b which advances to a specific direction. The figure which shows an example of the dispersion | variation in the magnitude | size (mass) of a metal cluster. Conceptual diagram showing another configuration example of the sputtering apparatus 100

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 Vacuum chamber, 13 Matching box, 15 Planar target, 15a Magnet, 15b Metal target material, 17 Plasma, 21 High frequency power supply, 23 Collimator, 25 Electrode plate, 25a Electrode plate (+), 25b Electrode plate (-), 27 Substrate Holder, 31 space, 40a to 40c, metal cluster (going in a specific direction), 50 silicon wafer, 100 sputtering apparatus

Claims (4)

In a film forming method of forming a film by colliding predetermined ions with a target in a vacuum chamber and depositing particles emitted from the target on a substrate,
Sorting the particles emitted from the target and traveling in a specific direction by their mass;
A film forming method, wherein the particles having a desired mass among the selected particles are collected and deposited on the substrate. In a sputtering apparatus that forms a film by colliding predetermined ions with a target in a vacuum chamber and depositing particles emitted from the target on a substrate.
A particle sorting means for passing only the particles emitted from the target and traveling in a specific direction and capturing the particles traveling in the other direction;
An electric field forming means for forming an electric field in a direction intersecting with the specific direction in a space in the chamber through which the particles selected by the particle selecting means pass next;
A sputtering apparatus comprising: a particle ionization unit that ionizes a surface of the particle before the particle reaches the space where the electric field is formed by the electric field forming unit. In a sputtering apparatus that forms a film by colliding predetermined ions with a target in a vacuum chamber and depositing particles emitted from the target on a substrate.
A particle sorting means for passing only the particles emitted from the target and traveling in a specific direction and capturing the particles traveling in the other direction;
Magnetic field forming means for forming a magnetic field in a direction intersecting with the specific direction in a space in the chamber through which the particles selected by the particle selecting means pass next;
A sputtering apparatus, comprising: a particle ionization unit that ionizes a surface of the particle before the particle reaches the space where the magnetic field is formed by the magnetic field forming unit.   4. The sputtering apparatus according to claim 2, wherein the direction intersecting with the specific direction is a direction orthogonal to the specific direction. 5.

Images