JP6824701B2 - Film formation method and film deposition equipment - Google Patents

Description

The present invention relates to a film forming method and a film forming apparatus.

With the progress of the miniaturization process in recent years, there is a demand for a technique of forming a trench or a hole (hereinafter, a trench or the like) having a high aspect ratio in a substrate and forming a layer having good coverage in the trench or the like. Under such circumstances, it is known that in a so-called magnetron sputtering apparatus, good coverage can be obtained by using a magnetic coil that generates magnetic lines of force between the sputtering target and the object to be processed (for example, patent). Reference 1).

International Publication 2011/007834

However, in such a technique, the thickness of the film-forming layer in the plane of the substrate becomes more uniform, and the coverage of the film-forming layer in the trench or the like in the plane of the substrate becomes more uniform. It has been demanded.

In view of the above circumstances, an object of the present invention is to make the thickness of the film-forming layer more uniform in the plane of the substrate, and further to improve the coverage of the film-forming layer in a trench or the like in the plane of the substrate. It is an object of the present invention to provide a film forming method and a film forming apparatus which become uniform.

In order to achieve the above object, in the film forming method according to one embodiment of the present invention, a substrate provided with a trench or the like in a vacuum chamber and a target material are opposed to each other, and the target material is sputtered to form the trench or the like. This includes forming a film-forming layer on the inside and on the surface of the substrate outside the trench or the like.
By generating plasma in the vacuum chamber while generating a magnetic field stronger on the outer periphery of the substrate than the center of the substrate by the magnetic coil, it is formed on the bottom surface of the trench and the surface of the substrate outside the trench and the like. The film-forming layer is etched back.
As a result, the thickness of the film-forming layer in the plane of the substrate becomes more uniform, and the coverage of the film-forming layer in the trench or the like in the plane of the substrate becomes more uniform.

In the above film forming method, the film forming layer may be etched back in a state where the annular conductors arranged around the substrate are electrically connected to the support base supporting the substrate.
As a result, when the film-forming layer is etched back, the electrolytic concentration on the outer periphery of the substrate is relaxed, the thickness of the film-forming layer in the surface of the substrate becomes more uniform, and further, in a trench or the like in the surface of the substrate. The coverage of the film layer becomes more uniform.

In the above-mentioned film forming method, the conductor may be arranged in a state of being projected from the substrate toward the target material.
As a result, when the film-forming layer is etched back, the concentration of electrolysis on the outer periphery of the substrate is further relaxed, the thickness of the film-forming layer in the surface of the substrate becomes more uniform, and a trench or the like in the surface of the substrate is further relaxed. The state of coverage of the film-forming layer in the above becomes more uniform.

In the above film forming method, the target material may be sputtered by plasma generated by a VHF power source.
As a result, sputter film formation by high-pressure high-density plasma becomes possible, and the thickness of the film-forming layer in the trench or the like becomes more uniform in the surface of the substrate.

In the above film forming method, the film forming layer may be formed on the substrate while a bias potential is applied to the substrate.
As a result, the direction of the ionic component in the high-pressure high-density plasma becomes more perpendicular to the substrate, and the thickness of the film-forming layer in the trench or the like becomes more uniform in the plane of the substrate.

The film forming method according to one embodiment of the present invention includes a vacuum chamber, a support base, a target material, a first plasma generation source, a second plasma generation source, and a magnetic coil.
The vacuum chamber can maintain a reduced pressure state.
The support base is provided in the vacuum chamber and can support the substrate.
With the target material provided in the vacuum chamber and arranged to face the support base,
The first plasma generation source can form a film-forming layer on the substrate by sputtering the target material.
The second plasma generation source can etch back the film-forming layer formed on the substrate by generating plasma in the vacuum chamber.
The magnetic coil can generate a strong magnetic field at the outer periphery of the substrate than at the center of the substrate when the film-forming layer is etched back.
As a result, the thickness of the film-forming layer in the plane of the substrate becomes more uniform, and the coverage of the film-forming layer in the trench or the like in the plane of the substrate becomes more uniform.

In the film forming apparatus, the length of the magnetic coil may be equal to or greater than the distance between the substrate and the target material in the direction from the substrate to the target material.
As a result, the plasma in the vacuum chamber spreads more from the center of the substrate toward the outer periphery, and the thickness of the film-forming layer in the plane of the substrate after etching back becomes more uniform.

The film forming apparatus further includes an annular conductor, a guard member, an insulator, and a ring member.
The annular conductor may be arranged around the substrate and electrically connected to the support.
The guard member may be arranged around the support and connected to a ground potential.
The insulator may be arranged on the guard member.
The ring member may be arranged around the conductor and placed on the insulator.
As a result, when the film-forming layer is etched back, the electrolytic concentration on the outer periphery of the substrate is relaxed, the thickness of the film-forming layer in the surface of the substrate becomes more uniform, and further, in a trench or the like in the surface of the substrate. The coverage of the film layer becomes more uniform.

In the above-mentioned film forming apparatus, the conductor may be configured so as to protrude toward the target material from the substrate.
As a result, when the film-forming layer is etched back, the concentration of electrolysis on the outer periphery of the substrate is further relaxed, the thickness of the film-forming layer in the surface of the substrate becomes more uniform, and a trench or the like in the surface of the substrate is further relaxed. The state of coverage of the film-forming layer in the above becomes more uniform.

As described above, according to the present invention, the thickness of the film-forming layer in the plane of the substrate becomes more uniform, and the coverage of the film-forming layer in the trench or the like in the plane of the substrate becomes more uniform. Become.

FIG. A is a schematic configuration diagram of a film forming apparatus applied to the film forming method according to the present embodiment. FIG. B is a schematic configuration diagram of a portion indicated by an arrow P in FIG. A. It is a schematic flow chart of the film formation method which concerns on this embodiment. FIG. A is a schematic configuration diagram of a film forming apparatus according to a comparative example. FIG. B is a schematic configuration diagram of a portion indicated by an arrow P in FIG. A. FIG. A is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface when the film-forming layer is formed on the substrate by sputtering using the film-forming apparatus according to the comparative example. FIG. B is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface after etching back the film-forming layer using the film-forming apparatus according to the comparative example. FIG. A is a schematic configuration diagram showing plasma formed in a vacuum chamber when the film forming layer is etched back by using the film forming apparatus according to a comparative example. FIG. B is a schematic configuration diagram showing a state of electric field concentration on the outer periphery of the substrate when the film forming layer is etched back by using the film forming apparatus according to the comparative example. FIG. A is a schematic configuration diagram showing a film forming layer in a trench at the center of a substrate before and after etching back is performed using the film forming apparatus according to a comparative example. FIG. B is a schematic configuration diagram showing a film-forming layer in a trench on the outer periphery of a substrate before and after etching-back is performed using the film-forming apparatus according to a comparative example. FIG. A is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface when the film-forming layer is formed on the substrate by sputtering using the film-forming apparatus according to the present embodiment. FIG. B is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface after etching back the film-forming layer using the film-forming apparatus according to the present embodiment. FIG. A is a schematic configuration diagram showing a state of a magnetic field in a vacuum chamber when a current is applied to the magnetic coil of the film forming apparatus according to the present embodiment. FIG. B is a schematic graph showing the distribution of the magnetic field strength in the Z-axis direction of the plasma forming space when a current is applied to the magnetic coil. FIG. A is a schematic configuration diagram showing plasma formed in a vacuum chamber when the film forming layer is etched back by using the film forming apparatus according to the present embodiment. FIG. B is a schematic configuration diagram showing a state of electric field concentration on the outer periphery of the substrate when the film forming layer is etched back by using the film forming apparatus according to the present embodiment. FIG. A is a schematic configuration diagram showing a film-forming layer in a trench at the center of a substrate before and after etching-back is performed using the film-forming apparatus according to the present embodiment. FIG. B is a schematic configuration diagram showing a film-forming layer in a trench on the outer periphery of a substrate before and after etching-back is performed using the film-forming apparatus according to the present embodiment. It is a schematic block diagram of the modification of the film forming apparatus which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. XYZ axis coordinates may be introduced in each drawing.

[Film formation device]
FIG. 1A is a schematic configuration diagram of a film forming apparatus applied to the film forming method according to the present embodiment. FIG. 1B is a schematic configuration diagram of a portion indicated by an arrow P in FIG. 1A.

The film forming apparatus 1 shown in FIG. 1A includes a vacuum chamber 10, a support base 20, a target material 30, a holder (backing plate) 31, a plasma generation source (first plasma generation source) 40, and a plasma generation source. A (second plasma generation source) 50 and a magnetic coil 60 are provided. Further, the film forming apparatus 1 includes a conductor 70, a guard member 80, a ring member 90, and an insulator 91.

The vacuum chamber 10 is a container capable of maintaining a reduced pressure state. A vacuum pump (not shown) such as a turbo molecular pump is connected to the vacuum tank 10. The atmosphere in the vacuum chamber 10 is maintained at a predetermined pressure by this vacuum pump. A gas supply source 15 is installed on the side wall 10w of the vacuum chamber 10. The gas supply source 15 supplies a gas for plasma discharge into the vacuum chamber 10. This gas is, for example, an inert gas (Ar, Ne, He, etc.). Further, a gas flow meter for adjusting the gas flow rate may be installed in the gas supply source 15. Further, the vacuum chamber 10 may be provided with a pressure gauge for measuring the pressure in the vacuum chamber 10.

The support base 20 is installed in the vacuum chamber 10. The substrate S1 to be processed is supported by the support base 20. The support base 20 has a structure including, for example, a metal. In the support base 20, the mounting surface 20a on which the substrate S1 is mounted may be a conductor or an insulator. For example, in the support base 20, an electrostatic chuck may be installed on the mounting surface 20a. Further, the support base 20 is provided with another mounting surface 20b that supports the conductor 70. The mounting surface 20b is annular and is provided around the mounting surface 20a. The mounting surface 20b is provided at a position lower than the mounting surface 20a. The outer circumference of the substrate S1 projects to the mounting surface 20b. Further, the support base 20 may have a built-in temperature control mechanism for cooling or heating the substrate S1 to a predetermined temperature.

The substrate S1 is, for example, any of a semiconductor substrate, an insulating substrate, a metal substrate, and the like. The semiconductor substrate is a silicon wafer, a silicon wafer having an insulating film formed on the surface, or the like. The insulating film is, for example, silicon oxide, silicon nitride, aluminum oxide, or the like. The diameter of the substrate S1 is, for example, 150 mm or more and 300 mm or less. However, the diameter of the substrate S1 is not limited to this example. The insulating substrate is a glass substrate, a quartz substrate, or the like.

The target material 30 is provided in the vacuum chamber 10. The target material 30 is arranged so as to face the support base 20. For example, the distance (T / S distance) between the substrate S1 and the target material 30 is 40 mm or more and 600 mm or less. The distance between the substrate S1 and the target material 30 is shorter than the distance between the substrate S1 and the protective plate 16. The material of the target material 30 is appropriately selected according to the composition of the film-forming layer formed on the substrate S1. For example, the material of the target material 30 contains at least one of copper (Cu), titanium (Ti), aluminum (Al), tantalum (Ta) and the like. The target material 30 is configured such that the area of the sputtered surface 30s is larger than the area of the substrate S1. Further, the planar shape of the target material 30 is appropriately adjusted according to the planar shape of the substrate S1.

The holder 31 supports the target material 30. The holder 31 is installed in the vacuum chamber 10 via the insulator 37. Inside, the holder 31 has a yoke 32 arranged in parallel with the target material 30, and magnets 33 and 34 provided on the lower surface of the yoke 32. The magnets 33 and 34 are arranged on the side opposite to the sputtered surface 30s of the target material 30. For example, in the example of FIG. 1A, in the magnet 33, the north pole is arranged so as to face the target material 30, and the south pole faces the yoke 32. On the other hand, in the magnet 34, the south pole is arranged so as to face the target material 30, and the north pole faces the yoke 32. As a result, a magnetic field is formed in the vicinity of the sputtered surface 30s of the target material 30 from the north pole of the magnet 33 to the south pole of the magnet 34.

The shapes and numbers of the magnets 33 and 34 are appropriately adjusted from the viewpoints of discharge stability, in-plane distribution of the film-forming layer of the substrate S1, and improvement of the use efficiency of the target material 30. For example, in the example of FIG. 1A, the magnets 33 and 34 have a flaky shape. The shapes of the magnets 33 and 34 may be a rod shape, or may be a combination of a flaky shape and a rod shape. Further, the yoke 32 is connected to the motor 39 via the shaft portion 38. As a result, the magnets 33 and 34 can be rotated in the holder 31 around the shaft portion 38.

The plasma generation source 40 (first plasma generation source) can form a film-forming layer on the substrate S1 by sputtering the target material 30. For example, the plasma generation source 40 has a high frequency power supply 41, a DC power supply 42, and a matching circuit 43. The plasma generation source 40 is connected to the holder 31. The matching circuit 43 is installed between the holder 31 and the high frequency power supply 41. The high frequency power supply 41 supplies electric power to the target material 30 via the holder 31. The high frequency power supply 41 is, for example, a VHF power supply (frequency: 60 MHz). The high frequency power supply 41 may be an RF power supply.

For example, when Ar gas is introduced into the vacuum chamber 10 and a predetermined power is applied to the target material 30 from the high frequency power supply 41, plasma is generated in the plasma forming space 10p in the vacuum chamber 10 by the capacitive coupling method. By using the VHF power supply as the high-frequency power supply 41, high-density plasma (hereinafter, high-voltage high-density plasma) is generated at high voltage (for example, 10 Pa or more and 30 Pa or less) in the plasma forming space 10p. However, the pressure may be 10 Pa or less. Further, since the high-density plasma is generated in the plasma forming space 10p, the self-bias potential is easily applied to the substrate S1. Further, the voltage applied to the substrate S1 may be adjusted by the high frequency power supply 50.

When Ar ions in the plasma collide with the sputtered surface 30s and the sputtered surface 30s is sputtered by Ar ions, the sputtered particles are scattered from the sputtered surface 30s toward the substrate S1. As a result, a film-forming layer is formed on the substrate S1. In this case, the film forming apparatus 1 functions as a film forming apparatus for forming a film forming layer on the substrate S1. Further, since this plasma is a high-pressure high-density plasma, many ions having a positive charge are generated in the plasma. Further, a bias potential can be applied to the substrate S1 by the high frequency power supply 50.

As a result, the direction in which the ions are scattered tends to be perpendicular to the substrate S1, and a film-forming layer having a substantially uniform thickness is formed on the entire surface of the substrate S1. Further, a film-forming layer is formed on the entire surface of the substrate S1 with good coverage in a fine trench or the like (aspect ratio: 4 or more). As an example, this film-forming layer can be used as a seed layer for a plating layer. In order to increase the sputtering efficiency of the target material 30, a predetermined negative potential may be applied to the target material 30 by the DC power supply 42. Further, the plasma generation source 40 is not limited to the capacitively coupled plasma source, and may be an inductively coupled plasma source.

The plasma generation source 50 (second plasma generation source) can etch back the film-forming layer formed on the substrate S1 by generating plasma in the vacuum chamber 10. The plasma generation source 50 has a high frequency power supply 50. The high frequency power supply 50 is, for example, an RF power supply (frequency: 13.56 MHz). The high frequency power supply 50 may be a VHF power supply. This plasma is formed by a capacitively coupled method.

The high frequency power supply 50 is connected to the support base 20. The high frequency power supply 50 can supply electric power to the substrate S1 via the support base 20. When, for example, Ar gas is introduced into the vacuum chamber 10 and plasma is generated in the plasma forming space 10p by the plasma generation source 50, the film-forming layer formed on the substrate S1 is etched back by the plasma. In this case, the film forming apparatus 1 functions as an etching apparatus for removing the film forming layer formed on the substrate S1. In the present embodiment, the etch back is used to mean that at least a part of the film-forming layer is removed from the surface of the film-forming layer by etching in the entire region of the film-forming layer. However, it may also mean that a part of the film-forming layer is exposed from, for example, the mask layer, and the film-forming layer in this part is selectively etched from the surface of the film-forming layer as etch back.

The magnetic coil 60 rotates around the outer circumference of the vacuum chamber 10, for example. The magnetic coil 60 is a spiral conducting wire, and this conducting wire is supported by a coil support (not shown). The magnetic coil 60 is arranged close to the vacuum chamber 10. The magnetic coil 60 may be arranged inside the vacuum chamber 10. For example, the magnetic coil 60 can generate a magnetic field in which the outer periphery of the substrate S1 is stronger than the center of the substrate S1 when the film forming layer is etched back. As a result, in the vacuum chamber 10, the plasma generated between the substrate S1 and the target material 30 spreads further from the center of the substrate S1 toward the outer circumference. As a result, the etching rate of the film-forming layer in the plane of the substrate S1 during etching becomes more uniform, and the thickness of the film-forming layer in the plane of the substrate S1 becomes more uniform after etching back.

The magnetic coil 60 is configured such that, for example, the length thereof is longer than the distance between the substrate S1 and the target material 30 in the direction from the substrate S1 toward the target material 30 (Z-axis direction). As a result, a magnetic field can be evenly generated in the plasma forming space 10p.

A power source (not shown) capable of energizing an electric current is connected to the magnetic coil 60. This power supply can arbitrarily change the value of the current supplied to the magnetic coil 60 and the direction of the current. For example, in the film forming apparatus 1, a magnetic field (current magnetic field) can be generated in the direction from the substrate S1 toward the target material 30, or a magnetic field can be generated in the direction from the target material 30 toward the substrate S1. The number of turns and the diameter of the magnetic coil 60 swirling around the outer circumference of the vacuum chamber 10 are not limited to the numbers shown in the figure. The number of turns and the diameter of the magnetic coil 60 are appropriately set according to, for example, the dimensions of the target material 30, the distance between the target material 30 and the substrate S1 and the like.

The conductor 70 is an annular conductor and is arranged around the substrate S1. The conductor 70 is installed on the mounting surface 20b of the support base 20 apart from the substrate S1. The conductor 70 is electrically connected to the support base 20. That is, the potential of the conductor 70 can be the same as the potential of the support 20.

The conductor 70 has a first conductor 70a in contact with the mounting surface 20b and a second conductor 70b provided on the first conductor 70a (FIG. 1B). In the X-axis direction (or Y-axis direction), the width of the second conductor 70b is narrower than the width of the first conductor 70a. The upper end 70t of the second conductor 70b is located, for example, at the same height as the film forming surface S1d of the substrate S1. The outer circumference of the substrate S1 is located on the first conductor 70a.

The guard member 80 is arranged around the support base 20. The guard member 80 has a structure including, for example, a metal. The guard member 80 is connected to the ground potential. The guard member 80 is provided apart from the support base 20. The upper end 80t of the guard member 80 is located, for example, at the same height as the mounting surface 20b of the support base 20.

The ring member 90 is an annular conductor and is arranged around the conductor 70. The ring member 90 is arranged on the insulator 91. The ring member 90 is provided apart from the conductor 70. As a result, the potential of the ring member 90 is electrically suspended.

The ring member 90 has a first ring member 90a in contact with the insulator 91 and a second ring member 90b provided on the first ring member 90a. In the X-axis direction (or Y-axis direction), the width of the second ring member 90b is wider than the width of the first ring member 90a. The upper end 90t of the second ring member 90b is located at the same height as the upper end 70t of the second conductor 70b, for example. A part of the second ring member 90b is located on the second conductor 70b.

The insulator 91 is arranged on the guard member 80. The insulator 91 is arranged, for example, around the conductor 70. The insulator 91 is arranged between the ring member 90 and the guard member 80. Further, in the film forming apparatus 1, the plasma forming space 10p and the ring member 90 are surrounded by the protective plate 16. The protective plate 16 is connected to the ground potential.

In the film forming apparatus 1, a conductor 70 electrically connected to the support base 20 is provided around the substrate S1. As a result, when the film-forming layer is etched back, the electrolytic concentration on the outer periphery of the substrate S1 is relaxed. As a result, the thickness of the film-forming layer in the in-plane of the substrate S1 after etching back becomes more uniform, and further, the state of coverage of the film-forming layer in the trench or the like in the in-plane of the substrate S1 becomes more uniform.

FIG. 2 is a schematic flow chart of the film forming method according to the present embodiment.
For example, in the present embodiment, the substrate S1 provided with a trench or the like in the vacuum chamber 10 and the target material 30 face each other. Then, by sputtering the target material 30 with the plasma generation source 40, a film-forming layer is formed on the surface of the substrate S1 inside the trench or the like and outside the trench or the like (step S10).

Next, the magnetic coil 60 generates a magnetic field in which the outer circumference of the substrate S1 is stronger than the center of the substrate S1. Then, by generating plasma in the vacuum chamber 10 by the plasma generation source 50, the film-forming layer formed on the bottom surface of the trench or the like and the surface of the substrate S1 outside the trench or the like is etched back (step S20).
As a result, the thickness of the film-forming layer in the plane of the substrate S1 after etching back becomes more uniform, and the state of coverage of the film-forming layer in the trench or the like in the plane of the substrate S1 becomes more uniform.

Before explaining the flow of FIG. 2 more specifically, the film forming apparatus according to the comparative example will be described.
FIG. 3A is a schematic configuration diagram of a film forming apparatus according to a comparative example. FIG. 3B is a schematic configuration diagram of a portion indicated by an arrow P in FIG. 3A.

In the film forming apparatus 5 according to the comparative example, the magnetic coil 60 and the conductor 70 are not provided (FIG. 3A). Further, in the film forming apparatus 5, the ring member 95 provided on the insulator 91 is close to the substrate S1 (FIG. 3B). For example, a part of the ring member 95 extends on the mounting surface 20b of the support base 20 and is provided close to the outer periphery of the substrate S1. The potential of the ring member 95 is electrically at the floating potential. The upper end 95t of the ring member 95 is located, for example, at the same height as the film forming surface S1d of the substrate S1.

FIG. 4A is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface when the film-forming layer is formed on the substrate by sputtering using the film-forming apparatus according to the comparative example. FIG. 4B is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface after etching back the film-forming layer using the film-forming apparatus according to the comparative example. Here, the horizontal axis of FIGS. 4A and 4B shows the positions of the center and the outer periphery of the substrate S1, and the vertical axis shows the thickness (standard value) of the film-forming layer.

As shown in FIG. 4A, when the film forming layer is formed on the substrate S1 by sputtering using the film forming apparatus 5, the thickness of the film forming layer in the plane of the substrate S1 becomes substantially uniform, and the substrate The thickness of the film-forming layer at the center of S1 and the thickness of the film-forming layer at the outer periphery of the substrate S1 are substantially the same. This is because the magnets 33 and 34 in the holder 31 are appropriately arranged so that the thickness of the film forming layer formed on the substrate S1 is substantially uniform, or the substrate is made by using high-pressure high-density plasma. This is because the film-forming layer was formed while applying a bias to S1.

However, when the film-forming layer is etched back by using the film-forming device 5, the etching rate at the center of the substrate S1 and the etching rate at the outer periphery of the substrate S1 become relatively high. As a result, the thickness of the film-forming layer after etching back becomes relatively thin at the center of the substrate S1 and the outer circumference of the substrate S1 (FIG. 4B). The reason for this will be described with reference to FIGS. 5A and 5B.

FIG. 5A is a schematic configuration diagram showing plasma formed in a vacuum chamber when the film forming layer is etched back by using the film forming apparatus according to a comparative example. FIG. 5B is a schematic configuration diagram showing a state of electric field concentration on the outer periphery of the substrate when the film forming layer is etched back by using the film forming apparatus according to the comparative example.

As shown in FIG. 5A, when the film forming layer is etched back by using the film forming apparatus 5, for example, the plasma 11 is formed in the plasma forming space 10p by the plasma generation source 50. Here, the distance between the substrate S1 and the target material 30 is shorter than the distance between the substrate S1 and the protective plate 16. As a result, the density of the plasma 11 becomes relatively high on the center of the substrate S1, and the etching rate becomes relatively high on the center of the substrate S1.

Further, at the time of etching back, a self-bias is applied to the substrate S1. Further, in the film forming apparatus 5, the ring member 95 having a floating potential is close to the outer periphery of the substrate S1. As a result, at the time of etching back, as shown in FIG. 5B, the electric field tends to be concentrated on the outer periphery of the substrate S1. This is because the ring member 95 shields the electric field toward the mounting surface 20b of the support base 20, and this electric field is concentrated on the outer periphery of the substrate S1. For example, in FIG. 5B, the electric field toward the substrate S1 at the time of etchback is represented by an arrow E5. As a result, in the film forming apparatus 5, plasma is concentrated even on the outer periphery of the substrate S1 having a high electric flux density, and the etching rate becomes relatively high.

As described above, in the film forming apparatus 5, the etching rate at the center of the substrate S1 and the etching rate at the outer periphery of the substrate S1 become relatively high, and after etching back, the film forming layer in the plane of the substrate S1 is formed. The thickness tends to be uneven.

Further, in the film forming apparatus 5, the thickness of the film forming layer in the trench or the like formed on the outer periphery of the substrate S1 becomes asymmetric after etching back. The reason for this will be described with reference to FIGS. 6A and 6B below.

FIG. 6A is a schematic configuration diagram showing a film-forming layer in a trench at the center of the substrate before and after etching-back is performed using the film-forming apparatus according to the comparative example. FIG. 6B is a schematic configuration diagram showing a film forming layer in a trench on the outer periphery of a substrate before and after etching back is performed using the film forming apparatus according to a comparative example. In FIGS. 6A and 6B, the film-forming layer before etching-back is shown on the left, and the film-forming layer after etching-back is shown on the right.

First, changes in the film forming layer 100 before and after etch back in the trench S1t at the center of the substrate S1 will be described.

For example, Ar gas is supplied to the vacuum chamber 10 and electric power is supplied to the target material 30 by the plasma generation source 40. The target material 30 is, for example, a copper target. Further, the high frequency power supply 50 supplies a bias potential to the substrate S1. As a result, the target material 30 is sputtered to form a film forming layer 100 on the surface (upper surface) S1u of the substrate S1 inside the trench S1t and outside the trench S1t (FIG. 6A left). The film forming layer 100 contains, for example, copper (Cu).

Copper ions are likely to be incident on the substrate S1 perpendicularly. As a result, the film-forming layer 100 is formed in the surface S1u and the trench S1t of the substrate S1 with good coverage. Here, the thickness of the film-forming layer 100 formed on the side surface S1w of the trench S1t is smaller than the thickness of the film-forming layer 100 formed on the surface S1u of the substrate S1 and the bottom surface S1b of the trench S1t. This is because the side surface S1w of the trench S1t is almost parallel to the direction in which the copper ions are scattered.

Next, as shown in the right figure of FIG. 6A, the film forming layer 100 is etched back. For example, Ar gas is supplied to the vacuum chamber 10, and electric power is supplied to the substrate S1 by the plasma generation source 50. As a result, Ar gas plasma is generated on the surface of the substrate S1. Here, in the vicinity of the center of the substrate S1, Ar ions in the plasma are likely to be incident perpendicularly to the substrate S1 due to the bias potential applied to the substrate S1. As a result, the film-forming layer 100 formed on the bottom surface S1b in the trench S1t and the surface (upper surface) S1u of the substrate S1 outside the trench S1t is preferentially etched back by Ar ions.

Here, the film forming layer 100 formed on the bottom surface S1b is resputtered on the side surface S1w of the trench S1t, and a part of the film forming layer 100 formed on the bottom surface S1b is formed again. That is, after etching back, the thickness of the film forming layer 100 formed on the bottom surface S1b of the trench S1t and the surface (upper surface) S1u of the substrate S1 outside the trench S1t is reduced, and the film formation layer 100 is formed on the side surface S1w of the trench S1t. The thickness of the film layer 100 increases. As a result, the thickness of the film-forming layer 100 formed in the trench S1t and on the surface (upper surface) S1u of the substrate S1 outside the trench S1t becomes substantially uniform. Further, the thickness of the film forming layer 100 in the trench S1t becomes symmetrical.

Next, changes in the film forming layer 100 before and after etch back in the trench S1t on the outer periphery of the substrate S1 will be described.

For example, in the film formation by sputtering, the film formation layer 100 having substantially the same shape as the left figure of FIG. 6A is formed on the outer periphery of the substrate S1 (FIG. 6B left figure).

Next, as shown in the right figure of FIG. 6B, the film forming layer 100 is etched back. Here, on the outer periphery of the substrate S1, the electric field E5 obliquely incident on the substrate S1 is concentrated (FIG. 5B). As a result, on the outer circumference of the substrate S1, the direction in which Ar ions are scattered is oblique due to the influence of the electric field E5. As a result, the film-forming layer 100 formed on one side surface S1w is preferentially etched. As described above, in the film forming apparatus 5, the thickness of the film forming layer 100 in the trench S1t becomes asymmetrical on the outer periphery of the substrate S1 after etching back.

On the other hand, a film forming method using the film forming apparatus 1 according to the present embodiment will be described below.

FIG. 7A is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface when the film-forming layer is formed on the substrate by sputtering using the film-forming apparatus according to the present embodiment. FIG. 7B is a schematic graph showing the thickness distribution of the film-forming layer in the substrate surface after etching back the film-forming layer using the film-forming apparatus according to the present embodiment. Here, the vertical axis of FIGS. 7A and 7B shows the thickness (standard value) of the film-forming layer.

As shown in FIG. 7A, when the film forming layer is formed on the substrate S1 by sputtering using the film forming apparatus 1, the thickness of the film forming layer in the plane of the substrate S1 becomes substantially uniform, and the substrate The thickness of the film-forming layer at the center of S1 and the thickness of the film-forming layer at the outer periphery of the substrate S1 are substantially the same. The reason for this is the same as the reason described in FIG. 4A as an example. As an example, the sputtering conditions are high frequency power supply (VHF power supply) 41: 5 kW, DC power supply 42: 3.2 kW, high frequency power supply (RF power supply) 50: 100 W, target material 30: copper target, discharge gas: argon.

Further, when the film forming layer is etched back by using the film forming apparatus 1, the etching rate in the plane of the substrate S1 becomes more uniform, and the etching rate at the center of the substrate S1 and the etching rate at the outer periphery of the substrate S1 become uniform. Becomes more uniform. As a result, after etching back, the thickness of the film-forming layer becomes more uniform at the center of the substrate S1 and the outer circumference of the substrate S1 (FIG. 7B). The reason for this will be described with reference to FIGS. 8A-9B.

FIG. 8A is a schematic configuration diagram showing a state of a magnetic field in a vacuum chamber when a current is applied to the magnetic coil of the film forming apparatus according to the present embodiment. FIG. 8B is a schematic graph showing the distribution of the magnetic field strength in the Z-axis direction of the plasma forming space when a current is applied to the magnetic coil. Here, the vertical axis of FIG. 8B shows the strength (standard value) of the magnetic field (Bz).

When a predetermined current is applied to the magnetic coil 60 arranged around the vacuum chamber 10, a magnetic field (Bz) from the substrate S1 toward the target material 30 is generated in the plasma forming space 10p (FIG. 8A). This magnetic field is generated, for example, when the film forming layer 100 is etched back. At the time of film formation, the magnetic field generated by the magnetic coil 60 is not generated. The direction of the magnetic field may be from the target material 30 toward the substrate S1. The average strength of the magnetic field in the plasma forming space 10p is, for example, 1 mT or more and 10 mT or less. Is. However, the strength of the magnetic field is set so as to increase from the center of the substrate S1 toward the protective plate 16 (FIG. 8B).

FIG. 9A is a schematic configuration diagram showing plasma formed in a vacuum chamber when the film forming layer is etched back by using the film forming apparatus according to the present embodiment. FIG. 9B is a schematic configuration diagram showing a state of electric field concentration on the outer periphery of the substrate when the film forming layer is etched back by using the film forming apparatus according to the present embodiment. As an example, the etching conditions are high frequency power supply 50 (RF power supply): 1.2 kW, discharge gas: argon, and magnetic coil: 6 A.

As shown in FIG. 9A, when the film forming layer is etched back by using the film forming apparatus 1, for example, the plasma 12 is formed in the plasma forming space 10p by the plasma generation source 50. Further, the magnetic coil 60 applies a magnetic field from the substrate S1 toward the target material 30 to the plasma forming space 10p. As a result, the plasma 12 spreads from the center of the substrate S1 toward the protective plate 16 more than the plasma 11 formed in the comparative example. As a result, the density of the plasma 12 becomes more uniform on the entire surface of the substrate S1.

Further, in the film forming apparatus 1, the conductor 70 connected to the support base 20 is close to the outer periphery of the substrate S1. As a result, during etchback, as shown in FIG. 9B, the electric field tends to concentrate on the outer circumference 70e of the conductor 70. For example, the electric field toward the mounting surface 20b of the support base 20 is shielded by the ring member 95, and the electric field is concentrated on the outer circumference 70e of the conductor 70. In FIG. 9B, the electric field toward the substrate S1 and the conductor 70 during etchback is represented by an arrow E1. In other words, in the film forming apparatus 1, the electric field concentrated on the outer periphery of the substrate S1 is relaxed, and the phenomenon of plasma concentrating on the outer periphery of the substrate S1 is also suppressed.

As a result, in the film forming apparatus 1, the etching rate in the plane of the substrate S1 becomes more uniform, and the etching rate at the center of the substrate S1 and the etching rate at the outer periphery of the substrate S1 become more uniform. As a result, after etching back, the thickness of the film-forming layer in the plane of the substrate S1 becomes more uniform (FIG. 7B).

Further, in the film forming apparatus 1, after etching back, the thickness of the film forming layer in the trench or the like formed on the outer periphery of the substrate S1 becomes more symmetrical. The reason for this will be described with reference to FIGS. 10A and 10B below.

FIG. 10A is a schematic configuration diagram showing a film-forming layer in a trench at the center of the substrate before and after etching-back is performed using the film-forming apparatus according to the present embodiment. FIG. 10B is a schematic configuration diagram showing a film-forming layer in a trench on the outer periphery of a substrate before and after etching-back is performed using the film-forming apparatus according to the present embodiment. In FIGS. 10A and 10B, the film-forming layer before etching-back is shown on the left, and the film-forming layer after etching-back is shown on the right.

First, changes in the film forming layer 100 before and after etch back in the trench S1t at the center of the substrate S1 will be described. As an example, the depth of the trench S1t is 200 nm, and the width of the bottom surface S1b is 45 nm.

For example, by sputtering the target material 30, the film forming layer 100 is formed on the surface (upper surface) S1u of the substrate S1 outside the trench S1t and inside the trench S1t (FIG. 10A, left). As described above, the film-forming layer 100 is formed in the surface S1u and the trench S1t of the substrate S1 with good coverage. Further, the thickness of the film forming layer 100 formed on the side surface S1w of the trench S1t is smaller than the thickness of the film forming layer 100 formed on the surface S1u of the substrate S1 and the bottom surface S1b of the trench S1t.

Next, as shown in the right figure of FIG. 10A, the film forming layer 100 is etched back. As described above, the Ar ion preferentially etches back the film forming layer 100 formed on the bottom surface S1b in the trench S1t and the surface (upper surface) S1u of the substrate S1 outside the trench S1t. Further, a part of the film forming layer 100 formed on the bottom surface S1b is formed by resputtering on the film forming layer 100 formed on the side surface S1w of the trench S1t. As a result, the thickness of the film-forming layer 100 formed in the trench S1t and on the surface (upper surface) S1u of the substrate S1 outside the trench S1t becomes substantially uniform. Further, the thickness of the film forming layer 100 in the trench S1t becomes symmetrical.

Next, changes in the film forming layer 100 before and after etch back in the trench S1t on the outer periphery of the substrate S1 will be described.

For example, in the film formation by sputtering, the film formation layer 100 having substantially the same shape as the left figure of FIG. 10A is formed on the outer periphery of the substrate S1 (FIG. 10B left figure).

Next, as shown in the right figure of FIG. 10B, the film forming layer 100 is etched back. Here, in the film forming apparatus 1, a conductor 70 connected to the support base 20 is provided on the outer periphery of the substrate S1, and the electric field E1 is concentrated on the conductor 70 (FIG. 9B). As a result, on the outer periphery of the substrate S1, the direction in which Ar ions are scattered tends to be perpendicular to the substrate S1 as in the center of the substrate S1. As a result, even on the outer periphery of the substrate S1, the thickness of the film forming layer 100 formed on the surface (upper surface) S1u of the substrate S1 outside the trench S1t becomes substantially uniform. Further, the thickness of the film forming layer 100 in the trench S1t becomes more symmetrical as in the center of the substrate S1. That is, if the film forming apparatus 1 is used, the coverage state of the film forming layer 100 in the trench S1t in the plane of the substrate S1 becomes more uniform.

Further, in the film forming method using the film forming apparatus 1, in order to adjust the thickness of the film forming layer 100 in the trench S1t, the film forming step on the substrate S1 and the etching step are alternately repeated. You may. In the above example, the trench S1t is exemplified, but the same effect as that of the trench S1t can be obtained for the holes formed in the substrate S1.

[Modification example of film forming apparatus]
FIG. 11 is a schematic configuration diagram of a modified example of the film forming apparatus according to the present embodiment. FIG. 11 illustrates a location corresponding to the portion indicated by the arrow P in FIG. 1A.

In the film forming apparatus 2, the conductor 70 connected to the support base 20 is configured to project from the substrate S1 toward the target material 30. For example, the upper end 70t of the conductor 70 is located at a position 0.5 mm or more and 3 mm higher than the film forming surface S1d of the substrate S1 and the upper end 90t of the ring member 90. Further, the upper end 70t of the conductor 70 is not limited to being flat, but may be curved or triangular.

As a result, during etchback, the electric field is more likely to be concentrated on the outer circumference 70e of the conductor 70 (arrow E2). In the film forming apparatus 2, the electric field concentrated on the outer periphery of the substrate S1 is further relaxed, and the phenomenon of plasma concentrating on the outer periphery of the substrate S1 is further suppressed.

As a result, in the film forming apparatus 2, the etching rate in the plane of the substrate S1 becomes more uniform, and the etching rate at the center of the substrate S1 and the etching rate at the outer periphery of the substrate S1 become more uniform. As a result, after etching back, the thickness of the film-forming layer in the plane of the substrate S1 becomes more uniform.

Further, in the film forming apparatus 2, since the electric field is further concentrated on the outer periphery 70e of the conductor 70, the thickness of the film forming layer in the trench or the like formed on the outer periphery of the substrate S1 becomes more symmetrical after etching back. Become. The state of coverage of the film forming layer 100 in the trench S1t in the plane of the substrate S1 becomes more uniform.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made.

1, 2, 5 ... Film formation device 10 ... Vacuum tank 10w ... Side wall 10p ... Plasma formation space 11, 12 ... Plasma 15 ... Gas supply source 16 ... Protective plate 20 ... Support base 20a, 20b ... Mounting surface 30 ... Target material 30s ... Spatter surface 31 ... Holder 32 ... Yoke 33, 34 ... Magnet 37 ... Insulator 38 ... Shaft 39 ... Motor 40 ... Plasma source 41 ... High frequency power supply 42 ... DC power supply 43 ... Matching circuit 50 ... Plasma source 60 ... Magnetic coil 70 ... Conductor 70a ... First conductor 70b ... Second conductor 70e ... Outer circumference 70t ... Upper end 80 ... Guard member 80t ... Upper end 90, 95 ... Ring member 90a ... First ring member 90b ... Second ring member 90t ... Upper end 95 ... Ring member 95t ... Upper end 91 ... Insulator 100 ... Film formation layer S1 ... Substrate S1t Trench S1w ... Side surface S1b ... Bottom surface S1d ... Film formation surface S1u ... Surface

Claims (8)

In a vacuum chamber to support the substrate trench or hole is provided in the support base, it is opposed to said substrate and a target material, by sputtering the target material, and in the trench or the bore, the trench A film-forming layer is formed on the outside or the surface of the substrate outside the holes,
Plasma is generated in the vacuum chamber in a state where an annular conductor electrically connected to the support base is arranged around the substrate while generating a magnetic field having a stronger outer periphery of the substrate than the center of the substrate by a magnetic coil. A film forming method for etching back the film forming layer formed on the bottom surface of the trench or the bottom surface of the hole and the surface of the substrate outside the trench or outside the hole by generating the film. The film forming method according to claim 1 .
A film forming method in which the conductor is arranged so as to project from the substrate toward the target material. The film forming method according to claim 1 or 2 .
A film forming method in which the target material is sputtered by plasma generated by a VHF power source. The film forming method according to any one of claims 1 to 3 .
A film forming method in which the film forming layer is formed on the substrate while a bias potential is applied to the substrate. A vacuum chamber that can maintain a decompressed state and
A support base provided in the vacuum chamber and capable of supporting the substrate, and
A target material provided in the vacuum chamber and arranged to face the support base, and
A first plasma generation source capable of forming a film-forming layer on the substrate by sputtering the target material,
A second plasma generation source capable of etching back the film-forming layer formed on the substrate by generating plasma in the vacuum chamber.
An annular conductor arranged around the substrate and electrically connected to the support.
A film forming apparatus including a magnetic coil capable of generating a strong magnetic field on the outer periphery of the substrate than the center of the substrate when the film forming layer is etched back. The film forming apparatus according to claim 5 .
In the direction from the substrate to the target material
A film forming apparatus in which the length of the magnetic coil is equal to or greater than the distance between the substrate and the target material. The film forming apparatus according to claim 5 or 6 .
A guard member arranged around the support and connected to the ground potential,
With the insulator arranged on the guard member,
A film forming apparatus further comprising a ring member arranged around the conductor and arranged on the insulator. The film forming apparatus according to claim 7 .
A film forming apparatus in which the conductor projects from the substrate toward the target material.