JP2019014924A - Sputtering apparatus and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering apparatus capable of maintaining self-discharge even when a collimator is provided between a target and a film-forming object, even after the introduction of a sputtering gas is stopped. SOLUTION: The magnetic field has a vacuum chamber 1 in which a target 21 and a film forming object W are arranged to face each other, and a magnet unit 4 is rotationally driven around the center of the target 21 to generate a leakage magnetic field in the space below the target 21. A space between the collimator 8 and the collimator 8 between the target 21 and the film forming object W is provided with the generating means 3, the sputter gas introducing means 10, and the power supply E1 for supplying power to the target 21. SM1 is a sputtering apparatus further comprising a magnetic field line generating means 9 capable of generating a downward magnetic field line MF and self-discharging after the introduction of the sputter gas is stopped. Preferably, the magnetic force generating means 9 is configured by a power source that energizes a coil wound around the side wall portion of the vacuum chamber 1, and is a sputtering device SM1 that generates a magnetic force line MF of 20 to 80 G. [Selection diagram] Fig. 1

Description

  The present invention relates to a sputtering apparatus and a sputtering method.

  The semiconductor device manufacturing process includes a step of forming a metal film such as a Cu film as a seed layer on the inner surface (inner wall surface and bottom surface) of a via hole or a contact hole, and a sputtering apparatus is used to form such a metal film. It is generally known to use. And with further miniaturization of wiring patterns in recent years, to form a film with good coverage over the entire surface of the substrate to be processed for high aspect ratio via holes, etc., that is, in order to satisfy the demand for improved coverage Among the sputtering apparatuses, a DC magnetron type sputtering apparatus using SIS (Self Ionized Sputter) technology is used (for example, see Patent Document 1).

  This type of sputtering apparatus has a vacuum chamber in which a metal target such as Cu and a substrate as a film formation target are disposed opposite to each other, and is disposed above the target with the direction from the target toward the substrate being downward. A magnetic field generating means for generating a tunnel-like leakage magnetic field in the lower space of the lever, a gas introducing means for selectively introducing a sputtering gas consisting of a rare gas into the vacuum chamber, and a sputtering power source for supplying power to the target. . When forming the metal film, when sputtering gas is introduced into the vacuum chamber in a vacuum atmosphere and a predetermined power having a negative potential is applied to the target, for example, plasma is generated in the lower space, and magnetic field generating means The plasma is confined in the lower space by the magnetic field generated by (especially, secondary electrons generated by sputtering are likely to be confined), and if the introduction of the sputtering gas is stopped in this state, self-discharge occurs at a low pressure. become. Sputtering gas ions in the plasma collide with the sputtering surface of the target and are sputtered, and sputtered particles and sputtered particle ions (hereinafter referred to as “sputtered particles”) generated by the sputtering are released into the space below the target. Then, a metal film is formed by adhering and depositing on the surface of the film formation target.

  By the way, in the sputtering apparatus, the target is preferentially sputtered in the region affected by the magnetic field in the target. For this reason, in order to erode the sputtering surface of the target substantially evenly and improve the usage efficiency of the target, for example, a so-called heart-shaped leakage magnetic field having zero vertical magnetic field component is formed, and this leakage magnetic field is formed during sputtering. In general, it is known that a magnet unit for generating a rotation is driven with the center of a target as a rotation center (see, for example, Patent Document 2). In such a method, the sputtered particles from the target enter and adhere to the outer peripheral portion of the substrate at an angle inclined with respect to the vertical direction, which may cause a problem of asymmetry of coverage at the outer peripheral portion of the substrate.

  In view of this, it is conceivable to arrange a collimator between the target and the film formation target that regulates the sputtered particles that incline beyond a predetermined range with respect to the vertical direction and reach the substrate. However, when applied to a DC magnetron type sputtering apparatus using SIS (Self Ionized Sputter) technology, it has been found that self-discharge can no longer be maintained if the introduction of the sputtering gas is stopped for some reason.

JP 2004-006942 A JP 2010-257515 A

  The present invention has been made in view of the above points, and even when a collimator is provided between a target and a film formation target in order to form a film with high coverage on the inner surface of a high aspect ratio hole, the sputtering gas It is an object of the present invention to provide a sputtering apparatus and a sputtering method capable of maintaining self-discharge after the introduction is stopped.

  In order to solve the above-mentioned problem, a vacuum chamber is provided in which a metal target and a film formation target are arranged to face each other, and the direction from the target toward the film formation target is set downward, and is disposed above the target. A magnetic field generating means for generating a tunnel-like leakage magnetic field in the lower space, a gas introducing means for selectively introducing a sputtering gas into the vacuum chamber, and a sputtering power source for supplying power to the target. The sputtering gas is introduced into the vacuum chamber of the atmosphere, and the target is powered on to generate plasma in the lower space. In this state, the introduction of the sputtering gas is stopped and the plasma is enclosed by the leakage magnetic field. In a sputtering apparatus that self-discharges and sputters the target, the magnetic field generating means has an equivalent immersion in the target. A magnet unit that generates the leakage magnetic field that forms a quantity; and a drive unit that rotationally drives the magnet unit around the center of the target, and is disposed between the target and the film formation target A collimator that regulates the sputtered particles scattered by sputtering of the target and that reaches the film formation target by inclining beyond a predetermined range with respect to the vertical direction, and the target and the collimator It is further provided with a magnetic force line generating means for generating downward magnetic force lines in the space between.

  According to the present invention, since the downward magnetic field lines are generated in the space between the target and the collimator, even when the collimator is provided between the target and the film formation target, self-discharge occurs after the introduction of the sputtering gas is stopped. It was confirmed that can be maintained. This is presumably because plasma is easily localized near the center of the sputtering surface of the target by generating downward magnetic lines of force in the space.

  In this invention, it is preferable that the said magnetic force line generation means is comprised by the coil wound along the outer peripheral surface of the side wall of a vacuum chamber, and the power supply which supplies with electricity to a coil.

  In this invention, it is preferable that the said magnetic force line generation | occurrence | production means generates the said magnetic force lines of 20G-80G.

  In the present invention, the magnetic field generating means preferably forms a heart-shaped leakage magnetic field having a vertical magnetic field component of zero on the target surface.

  In order to solve the above-mentioned problem, a metal target and a film formation target are disposed opposite to each other in a vacuum chamber, and a direction from the target toward the film formation target is downward, and a space below the target In a state where a tunnel-like leakage magnetic field is generated, the sputtering gas is introduced into the vacuum chamber in a vacuum atmosphere, and power is supplied to the target to generate plasma in the lower space. The present invention is such that the introduction is stopped, the plasma is confined by the leakage magnetic field, self-discharge is performed, the target is sputtered, and the sputtered particles generated by the sputtering are adhered and deposited on the surface of the film formation object to form a metal film. In the sputtering method, during sputtering, a leakage magnetic field that forms an equivalent amount of erosion on the target is rotating around the center of the target. The sputtered particles are tilted beyond a predetermined range with respect to the vertical direction by the collimator disposed between the target and the film formation target, and reach the film formation target. And a downward magnetic field line is generated in the space between the target and the collimator.

The typical sectional view showing the sputtering device of the embodiment of the present invention. The typical sectional view showing the sputtering device of the modification of the present invention.

  Hereinafter, with reference to the drawings, a sputtering apparatus according to an embodiment of the present invention will be described with reference to an example in which a Cu film, which is a metal film, is formed on the surface of a film formation target W.

  Referring to FIG. 1, SM1 is a DC magnetron type sputtering apparatus, and this sputtering apparatus SM1 includes a vacuum chamber 1 that defines a processing chamber 1a. A cathode unit C is attached to the ceiling of the vacuum chamber 1. In the following description, the direction facing the ceiling portion side of the vacuum chamber 1 will be referred to as “up”, and the direction facing the bottom portion side will be described as “down”.

The cathode unit C includes a target assembly 2 and a magnetic field generating unit 3 disposed above the target assembly 2. The target assembly 2 includes a Cu target 21 formed in a circular plate shape in a plan view according to a contour of the film formation target W, and a bonding material such as indium (not shown) on the upper surface of the target 21. ), And the target 21 can be cooled by allowing a coolant (cooling water) to flow inside the backing plate 22 during sputtering. With the target 21 mounted, the peripheral edge of the lower surface of the backing plate 22 is attached to the upper part of the vacuum chamber 1 via the insulators I ₁ and I ₂ . An output from a sputtering power source E1 such as a DC power source or a high frequency power source is connected to the target 21, and power having a negative potential is applied to the target 21 during sputtering.

  The magnetic field generating means 3 includes a magnet unit 4 and a driving means 5 such as a motor that rotationally drives the magnet unit 4. The magnet unit 4 is arranged in, for example, a substantially heart shape so as to surround the periphery of the magnet body 42, a yoke 41, a plurality of magnet bodies 42 of the same magnetization arranged in a substantially heart shape on the lower surface of the yoke 41, and the like. It is composed of a magnet body 42 and a plurality of magnet bodies 43 having the same magnetization. As a result, a tunnel-like leakage magnetic field is locally generated between the center of the target 21 and the outer peripheral edge thereof to supplement the electrons ionized below the sputter surface 21a of the target 21 during sputtering. In order to contain the plasma. Further, the rotation shaft 51 of the drive means 5 is connected to the upper surface of the yoke 41, and the rotation of the rotation shaft 51 by the drive means 5 causes the magnet unit 4 to rotate around the center of the target 21 to cause leakage. The magnetic field is circulated around the center of the target 21.

A stage 6 is disposed at the bottom of the vacuum chamber 1 so as to face the target 21 so that the film formation target W can be positioned and held with its film formation surface facing upward. Stage 6 is held by the insulator I ₃ attached airtightly to an opening provided in the bottom wall of the vacuum chamber 1. The stage 6 is connected to the output of the high-frequency power source E2, and during sputtering, a bias potential is applied to the stage 6 and eventually the film formation target W, and the ionized sputter particles are actively drawn into the film formation target W. I try to fulfill. In addition, the space | interval between the target 21 and the film-forming target W can be set to the range of 300 mm-600 mm, for example.

  A conductive anode shield 7 is disposed inside the side wall of the vacuum chamber 1. The anode shield 7 is a cylindrical member that covers the periphery of the target 21 and extends downward. The anode shield 7 is connected to another DC power source E3, and a positive potential is applied during sputtering to reflect ionized sputtered particles to assist incidence on the film formation target W.

Between the target 21 and the film-forming target W, a collimator that regulates the sputtered particles scattered by sputtering that incline beyond a predetermined range with respect to the vertical direction and reach the film-forming target W 8 is disposed, and a plurality of through holes 81 are formed in the collimator 8. Collimator 8, the lower end of the inner surface of anode shield 7 is fixed through an insulator I _4, is separated from the potential of anode shield 7, and is in an electrically floating.

  Note that the shape of the through hole 81 in a plan view is arbitrary, and may be formed, for example, in a circle or a hexagonal shape to form a honeycomb structure. Further, the depth of the through-hole 81 opened in the central portion of the collimator 8 (that is, the thickness of the central portion of the collimator 8) is the depth of the through-hole 81 opened in the outer peripheral portion (that is, the outer peripheral portion of the collimator 8). The thickness may be deeper (thicker) than (thickness). In this case, the thickness of the collimator 8 can be set in a range of 53 mm to 137.4 mm, for example, and the distance between the collimator 8 and the target 21 can be set in a range of 85 mm to 180 mm, for example. .

  In addition, a coil 9 formed by winding a conducting wire 92 around a ring-shaped yoke 91 is provided on the side wall of the vacuum chamber 1, and the output of the power source E 4 is connected to the conducting wire 92 so that the coil 9 can be energized. Yes. By energizing the coil 9, downward magnetic lines of force MF can be generated in the space between the target 21 and the collimator 8. Note that the position of the coil 9 and the diameter and the number of turns of the conductive wire 92 are, for example, the area of the sputtering surface 21a of the target 21, the distance between the target 21 and the film formation target W, the rated current value of the power source E4, and the like. It is appropriately set according to the magnetic field strength (Gauss) to be performed.

  Connected to the side wall of the vacuum chamber 1 is a gas pipe 10 as gas introducing means for introducing a rare gas such as argon gas as a sputtering gas for generating plasma. The gas pipe 10 communicates with a gas source (not shown) via a mass flow controller 10 a so that a sputter gas whose flow rate is controlled can be selectively introduced into the vacuum chamber 1. The bottom of the vacuum chamber 1 is connected to an exhaust pipe 11 communicating with a vacuum exhaust means P such as a turbo molecular pump or a rotary pump so that the vacuum chamber 1 can be evacuated and maintained at a predetermined pressure.

  The sputtering apparatus SM1 has a known control means 12 including a microcomputer, a sequencer, and the like. The control means 12 operates the power sources E1 to E4, the mass flow controller 10a, and the vacuum exhaust means P. The operation of the means 5 is integrated and managed. Hereinafter, the sputtering method according to the embodiment of the present invention will be described by taking as an example the case where a Cu film is formed on the film formation target W using the sputtering apparatus SM1.

First, the film formation target W is placed on the stage 6 in the vacuum chamber 1 to which the Cu target 21 is assembled, and the evacuation means P is operated to move the inside of the processing chamber 1a to a predetermined degree of vacuum (for example, 1 Vacuum is drawn up to × 10 ⁻⁵ Pa). When the pressure in the vacuum chamber 1 reaches a predetermined value, the magnetic unit 4 is rotated by the driving unit 5, thereby causing a leakage magnetic field formed unevenly distributed between the center of the target 21 and the outer peripheral edge of the target 21. The center of rotation is driven to rotate. At the same time, the mass flow controller 10a is controlled to introduce argon gas as a sputtering gas into the processing chamber 1a at a predetermined flow rate (for example, 10 to 30 sccm) (at this time, the pressure in the processing chamber 1a is 7. 3 × 10 ^{−2 to} 2.1 × 10 ⁻¹ Pa). Further, by applying predetermined DC power (for example, 20 to 25 kW) to the target 21, plasma is generated in the space below the sputtering surface 21a of the target 21, and after a predetermined time has elapsed since the plasma was generated, While the power supply to the target 21 is continued, the mass flow controller 10a is controlled to stop the introduction of the sputtering gas and self discharge. Thereby, the target 21 is sputtered, and the sputtered particles adhere to and deposit on the film formation target W, whereby a Cu film is formed. At this time, by applying a positive potential (for example, 50 V to 150 V) to the anode shield 7 and applying a bias power (for example, 0 W to 600 W) to the stage 6, ionized sputtered particles (Cu ions) are formed into the film formation target W. Can be pulled in efficiently. Further, the collimator 8 arranged between the target 21 and the film formation target W regulates the sputtered particles that reach the film formation target W by tilting beyond a predetermined range with respect to the vertical direction. Is done.

  When a predetermined time elapses after the plasma is generated as described above, the mass flow controller 10a is controlled to stop the introduction of the sputtering gas while the power supply to the target 21 is continued. It has been found that when the collimator 8 is disposed between the film 21 and the film formation target W, self-discharge cannot be maintained.

  In the present embodiment, the coil 9 is energized from the power source E4 (at this time, the current flowing through the coil 9 is 4 to 12 A), and a downward magnetic force line MF is generated in the space between the target 21 and the collimator 8. The self-discharge can be maintained after the introduction of the sputtering gas is stopped. This is because by generating a downward magnetic field line MF in the space, the magnetic field on the target 21 is diverged (directed toward the film formation target W), thereby promoting the maintenance of self-discharge. it is conceivable that.

In order to confirm the above effects, the following experiment was performed using the sputtering apparatus SM1 of the above embodiment. In the inventive experiment, a silicon oxide film having a thickness of 100 nm was formed on the surface of a Φ300 mm silicon substrate as the film formation target W, and the aspect ratio was 2.7 (the diameter of the opening was about 30 nm, the depth was The film formation target W is placed on the stage 6 in the vacuum chamber 1 on which a Φ400 mm target 21 made of Cu is assembled, and the pressure in the processing chamber 1a is 1 × 10 6. ^{When -5} Pa is reached, the magnet unit 4 is rotated at 60 rpm, 10 sccm of argon gas is introduced into the processing chamber 1a, and about 25 kW of DC power is supplied to the target 21 (at this time, the current flowing through the target 21 is 46 A). ) Plasma was generated. At this time, a bias power of 200 W was applied to the stage 6 and a positive potential of 50 V was applied to the anode shield 7. After 1 second from the generation of plasma, the introduction of argon gas was stopped. At this time, it was confirmed that self-discharge can be maintained by energizing the coil 9 (coil current is 8A) and generating downward magnetic lines of force MF (20G to 80G) in the space between the target 21 and the collimator 8. . Thereby, the target 21 is sputtered, and the sputtered particles scattered from the target 21 adhere to and deposit on the surface of the film formation target W including the inner surface of the hole to form a Cu film. After film formation for about 45 seconds by self-discharge, it was confirmed that a Cu film can be formed on the inner surface of the hole at the center and edge of the film formation target W with good coverage.

  In addition, after the plasma was generated under the same conditions as in the above experiment except that the coil current was set to 4A and 12A by controlling the voltage applied from the power source E4 to the coil 9, the introduction of argon gas was stopped. In these cases, it was confirmed that the self-discharge can be maintained. It was also confirmed that a Cu film can be formed on the inner surface of the hole with good coverage.

  Further, except that the bias power applied to the stage 6 was set to 0 W, 400 W, and 600 W, plasma was generated under the same conditions as in the above experiment, and then the introduction of argon gas was stopped. It was confirmed that self-discharge can be maintained. It was also confirmed that a Cu film can be formed on the inner surface of the hole with good coverage.

  Further, except that the positive potential applied to the anode shield 7 was 150 V, plasma was generated under the same conditions as in the above experiment, and then the introduction of argon gas was stopped. In these cases, self-discharge was maintained. It was confirmed that it was possible. It was also confirmed that a Cu film can be formed on the inner surface of the hole with good coverage. That is, it was confirmed that the self-discharge can be maintained if the downward magnetic field lines MF generated in the space between the target 21 and the collimator 8 are 20G to 80G.

  The amount of erosion of the target 21 when the film was formed under the same conditions as in the above experiment was obtained. The amount of erosion was obtained by subtracting the thickness of the target 21 after film formation from the thickness of the target 21 before film formation. The thickness of the target 21 after film formation is the thickness of the target 21 after the Cu film is formed with an integrated power of 50 kWh. According to this, it is confirmed that the sputtering surface 21a of the target 21 is eroded substantially evenly in the radial direction by rotating the magnet unit 4 and causing the leakage magnetic field to circulate around the center of the target 21 during sputtering. It was. That is, it was confirmed that the leakage magnetic field formed an equivalent amount of erosion on the target. From this, it was found that the plasma was dispersed over the entire sputtering surface of the target. Here, being eroded substantially uniformly (forming an equivalent amount of erosion) means that the usage efficiency of the target 21 is 50% or more, and erosion when the target 21 is used until the end of its life (life end). It is meant that the volume made is 50% or more before using the target.

  Next, a comparative experiment with respect to the above-described invention experiment was performed. In the comparative experiment, when the introduction of the argon gas is stopped after the plasma is generated, the coil 9 is not energized (that is, the downward magnetic field lines MF are not generated in the space between the target 21 and the collimator 8). Except for this, sputtering was performed under the same conditions as in the above-described invention experiment. According to this, it was confirmed that when the introduction of the argon gas was stopped, the self-discharge could not be maintained (that is, the plasma was deactivated). In addition, even when the coil current of the coil 9 was 3A, 13A, and 20A, it was confirmed that self-discharge could not be maintained if the introduction of argon gas was stopped. When the coil current is smaller than 4 A, the force for directing ions sputtered from the target to the film formation target is weak. Therefore, when the coil current is larger than 12 A, the magnetic force directed to the film formation target is high, and the target It is presumed that the self-discharge cannot be maintained because the number of ions to be sputtered decreases.

  According to the invention experiment and comparative experiment described above, it has been found that by generating downward magnetic field lines in the space between the target 21 and the collimator 8, self-discharge can be maintained after the introduction of the sputtering gas is stopped.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. In the above embodiment, the coil 9 is disposed on the side wall portion of the vacuum chamber 1 surrounding the collimator 8, but the position of the collimator 8 is not limited to this, and the space between the collimator 8 and the film formation target W is defined. You may arrange | position a coil in the side wall part of the vacuum chamber 1 to surround. Further, the number of coils constituting the magnetic force line generating means is not limited to one, and two coils 9u and 9d are arranged on the side wall of the vacuum chamber 1 at a predetermined interval in the vertical direction as in the sputtering apparatus SM2 shown in FIG. The coils 9u and 9d may be energized from the power sources E4 and E5. In this case, it is sufficient to energize at least one of the coils 9u and 9d. The distance between the coils 9u and 9d is, for example, the area of the sputtering surface 21a of the target 21, the distance between the target 21 and the film formation target W, the rated current values of the power supplies E4 and E5, and the magnetic field strength ( It can be set appropriately according to (Gauss).

  In the above embodiment, the case where the magnetic force line generating means is constituted by the coil 9 has been described as an example. However, any means that generates downward magnetic force lines in the space between the target 21 and the collimator 8 may be used. You may make it generate | occur | produce a downward magnetic force line in the said space by arrange | positioning a binding magnet inside the side wall of the vacuum chamber 1, or the outer side.

MF ... Magnetic field lines, SM ... Sputtering apparatus, W ... Film formation target, 1 ... Vacuum chamber, 21 ... Target, 3 ... Magnetic field generating means, 4 ... Magnet unit, 5 ... Driving means, 8 ... Collimator, 9, 9u, 9d ... coil (magnetic line generation means), 10 ... gas pipe (gas introduction means), E1 ... sputter power supply, E4, E5 ... power supply for energizing the coil.

Claims (5)

It has a vacuum chamber in which a metal target and a film formation target are arranged to face each other, and a direction from the target toward the film formation target is set downward, and is disposed above the target and is tunnel-shaped in a space below the target. A magnetic field generating means for generating a leakage magnetic field, a gas introducing means for selectively introducing a sputtering gas into the vacuum chamber, and a sputtering power source for supplying power to the target. Sputtering gas is introduced, power is applied to the target to generate plasma in the lower space. In this state, introduction of the sputtering gas is stopped, the plasma is confined by the leakage magnetic field, and the target is sputtered. A sputtering apparatus for
The magnetic field generating means has a magnet unit that generates the leakage magnetic field that forms an equivalent amount of erosion on the target, and a driving means that rotationally drives the magnet unit around the center of the target.
Among the sputtered particles that are arranged between the target and the film formation target and are scattered by sputtering of the target, the particles that incline beyond a predetermined range with respect to the vertical direction and reach the film formation target A sputtering apparatus, further comprising: a collimator that regulates a magnetic field; and a magnetic force line generating unit that generates a downward magnetic force line in a space between the target and the collimator.   2. The sputtering apparatus according to claim 1, wherein the magnetic force line generating means includes a coil wound around a side wall portion of the vacuum chamber orthogonal to the vertical direction and a power source for energizing the coil.   The sputtering apparatus according to claim 1, wherein the magnetic force line generating unit generates the magnetic force lines of 20G to 80G.   The sputtering apparatus according to claim 1, wherein the magnetic field generation unit forms a heart-shaped leakage magnetic field having a vertical magnetic field component of zero on the target surface. In the vacuum chamber, a metal target and a film formation target are arranged to face each other, and a tunnel-like leakage magnetic field is generated in a space below the target with the direction from the target toward the film formation target being downward. In this state, the sputtering gas is introduced into the vacuum chamber in a vacuum atmosphere, and power is supplied to the target to generate plasma in the lower space. In this state, introduction of the sputtering gas is stopped and the plasma is leaked. A sputtering method in which a metal film is formed by depositing and depositing sputtered particles generated by sputtering on a surface of an object to be deposited by sputtering the target by enclosing with a magnetic field and performing self-discharge,
During sputtering, a leakage magnetic field that forms an equivalent amount of erosion on the target is rotationally driven with the center of the target as the center of rotation, and among the sputtered particles by a collimator disposed between the target and the film formation target, A sputtering method characterized by regulating an object that reaches the film formation target inclining beyond a predetermined range with respect to the vertical direction, and generates downward magnetic force lines in a space between the target and the collimator .

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