JP2015178653A - Sputtering device and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering device having a structure capable of effectively suppressing neutral sputter particles scattered from a sputter surface of a target from impinging on a substrate.SOLUTION: A sputtering device includes a processing chamber 11, gas introduction means 6 of introducing a sputter gas into the processing chamber, and a sputter power source E1 which supplies electric power to a target T provided facing the processing chamber. The processing chamber is partitioned by a cylindrical body 1 which has the target and a substrate arranged at both end opening parts Cs1, Cs2 respectively, and the cylindrical body is configured to have a curved part 12 at at least one place so as to introduce the sputter gas into the processing chamber, neutral sputter particles scattered from the target not reaching the substrate directly when the target is supplied with electric power to be sputtered. Magnetic field generation means 5, E3 of generating a magnetic field between the target and substrate so that lines of magnetic force corresponding to the outline of the cylindrical body pass are provided at a periphery of the cylindrical body to allow ionized sputter particles to reach the substrate.

Description

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

  Conventionally, a sputtering apparatus has been used to form various thin films, for example, in a semiconductor device manufacturing process. Among them, a copper film or the like is bottom-covered with respect to a substrate to be processed having high aspect ratio fine holes. For example, Patent Document 1 discloses a technique using a SIS (Self-Ionized Sputtering) technique that can form a film well.

  This includes a processing chamber that is evacuated, a gas introduction unit that introduces a sputtering gas into the processing chamber, and a sputtering power source that supplies power to a target that is disposed opposite to a substrate provided in the processing chamber. In addition, this has a predetermined interval over the entire surface of the magnet unit that generates a magnetic field below the target, the sputtering surface side of the target, the sputtering surface of the target, and the substrate disposed opposite to the target. Magnetic field generating means for generating a vertical magnetic field so that a vertical magnetic field line passes therethrough.

  When sputtering is performed by applying a predetermined power having a negative potential to the target in a state where a vertical magnetic field is generated so that a vertical magnetic field line passes through the film by sputtering, sputtering of the sputtered particles scattered from the sputtering surface occurs. Since the ionization is promoted and the ionized sputtered particles have a positive charge, the direction is changed by the vertical magnetic field, and the ionized sputtered particles are incident on and adhered to the substrate substantially perpendicularly. In this case, in the above-mentioned conventional example, at the start of sputtering, plasma is generated in the space below the sputtering surface by introducing a sputtering gas consisting of a rare gas into the processing chamber, and is generated below the sputtering surface by the magnet unit. When the plasma is confined in the magnetic field, the introduction of the sputtering gas is stopped and the self-discharge is performed under a low pressure (so-called self-holding discharge).

  As a result, while suppressing the sputtering gas reflected by the target or the like from being incident on the substrate, the ionization rate of the sputtered particles is increased, and the ratio of the ionized sputtered particles incident on the substrate with a vertical component is increased. . However, in the above-described conventional example, there is a large proportion of neutral sputtered particles that are scattered with a large angular spread from the sputtered surface of the target until the self-maintained discharge is performed. Depending on the form, there is a problem that bottom coverage is deteriorated (that is, fine holes such as contact holes are blocked).

No. 2009/150997

  In view of the above, the present invention provides a sputtering apparatus having a structure capable of effectively suppressing the incidence of neutral sputtered particles scattered from a sputtering surface of a target onto a substrate, and a sputtering method using the same. Let that be the issue.

  In order to solve the above-described problems, the present invention includes a processing chamber that is evacuated, a gas introduction unit that introduces a sputtering gas into the processing chamber, and a sputtering power source that supplies power to a target provided to face the processing chamber. In the sputtering apparatus, a processing chamber is defined by a cylindrical body in which a target and a substrate to be processed are respectively disposed at openings at both ends, and the cylindrical body has at least one curved portion in the processing chamber. It is configured so that neutral sputtered particles scattered from the target do not directly reach the substrate when the sputtering gas is introduced and power is applied to the target for sputtering, and around the cylindrical body between the target and the substrate. A magnetic field generating means for generating a magnetic field so that the magnetic field lines corresponding to the contour of the cylindrical body pass is provided so that ionized sputtered particles reach the substrate. To.

  According to the present invention, the substrate to be processed and the target are set in the opening portions at both ends of the cylindrical body, and then the processing chamber is evacuated. When the processing chamber reaches a predetermined pressure, a sputtering gas consisting of a rare gas is introduced, and when a predetermined power having a negative potential is applied to the target, for example, plasma is generated in the space between the target and the substrate, Sputtered. At this time, since the cylindrical body has a curved portion so that the neutral sputtered particles scattered from the sputtering surface of the target do not directly reach the substrate, the neutral sputtered particles are incident on the substrate. Can be effectively suppressed.

  When the magnetic field generating means generates a magnetic field so that the magnetic field lines corresponding to the outline of the cylindrical body pass between the target and the substrate, ionization of the sputtered particles scattered from the sputtering surface is promoted, while However, the magnetic field lines perpendicular to the film-forming surface of the substrate pass, and the ionized sputtered particles are changed in direction along the magnetic field and are incident and deposited almost perpendicularly to the substrate. To form a film. As a result, when the substrate to be processed has fine holes with a high aspect ratio, the film can be formed only with ionized sputtered particles incident on the substrate with a vertical component, thereby improving bottom coverage. Can do.

  In the present invention, the cylindrical body preferably has an L-shaped contour. Thereby, it is possible to realize a configuration in which neutral sputtered particles scattered from the target do not reach the substrate directly with a simple structure of the cylindrical body. The curved portion of the present invention includes a case where the cylindrical body is bent by 90 ° so that the sputtering surface of the target and the film formation surface of the substrate are orthogonal to each other.

  In the present invention, it is preferable that the cylindrical body further includes a potential generating means for converging the ionized sputtered particles toward the substrate. As a result, the total amount of ionized sputtered particles incident on the substrate having a vertical component is increased, the film formation rate is improved, and mass productivity can be increased. In this case, as the potential generating means, a configuration including a conductive plate member provided so as to cover the inner surface of the cylindrical body and a power source for applying a positive potential to the plate member may be employed.

  By the way, since the cylindrical body has at least one curved portion, a magnetic field gradient is generated when a magnetic field is generated so that a magnetic field line corresponding to the outline of the cylindrical body passes between the target and the substrate. If so, the in-plane uniformity of the film thickness distribution of the substrate may be impaired. In such a case, it is preferable to further include a stage that opens and holds one surface of the substrate and rotationally drives the substrate at a constant rotational speed.

  In order to solve the above-described problem, the sputtering method of the present invention using the sputtering apparatus includes a sputtering gas in a vacuum-evacuated processing chamber when the magnetic field generating unit that does not generate a magnetic field by the magnetic field generating unit is stopped. The first step of sputtering by applying power to the target, the second step of stopping the introduction of the sputtering gas while maintaining the power input to the target, and operating the magnetic field generating means to ionized sputtered particles And a third step of depositing and depositing ionized sputtered particles on one surface of the substrate so as to reach the substrate and forming a film.

  According to this, by not operating the magnetic field generating means until so-called self-holding discharge, it is possible to more surely prevent the incident of ions other than the ionized sputtered particles scattered from the sputtering surface of the target. In this case, it is preferable to further include a step of operating the potential generating means in the third step to converge the ionized sputtered particles toward the substrate.

The perspective view which shows the structure of the sputtering device of this invention. FIG. 2 is a schematic cross-sectional view showing an internal structure of the sputtering apparatus in FIG. 1. The graph which shows the experimental result of this invention.

  Hereinafter, with reference to the drawings, the target T is made of copper, the substrate W to be processed is formed with a plurality of high aspect ratio fine holes formed on one surface, and a Cu film is formed on the one surface. An embodiment of the sputtering apparatus of the present invention will be described by taking as an example. In the following, terms indicating directions such as “up”, “down”, “left”, and “right” are based on FIG.

  1 and 2, SM is a DC magnetron sputtering type sputtering apparatus capable of so-called self-sustained discharge. The sputtering apparatus SM includes a cylindrical body 1 as a vacuum chamber that defines a processing chamber 11. In addition, the cross-sectional shape of the cylindrical body 1 is not limited to a circle but may be a rectangle or the like. A single curved portion 12 is formed in the central portion of the cylindrical body 1 so as to have a positional relationship in which neutral sputtered particles scattered from the sputter surface Tp of the target T do not directly reach the substrate W, and are substantially L-shaped. It has a contour of a shape. The cylindrical body 1 is supported by the support base 14 in such a posture that the one end opening 13a faces rightward in FIG. 1 and the other end opening 13a faces downward.

  A cathode unit C is attached to one end opening 13 a of the cylindrical body 1 so that the target T faces the processing chamber 11. The cathode unit C includes a first support Cs1 that also serves as a lid that closes the one end opening 13a of the cylindrical body 1, and the target T is supported by the first support Cs1. Note that the target T is not limited to copper, and is appropriately selected according to the composition of the thin film to be formed on the substrate W to be processed. For example, the target T is made of tungsten, tantalum, or titanium. It is also possible to make a predetermined shape by a known method. And it attaches to the 1st support body Cs1 through the insulator Is in the state which bonded the backing plate Bp to the surface opposite to the sputtering surface Tp. The target T is connected to a DC power source E1 as a sputtering power source, and a predetermined power having a negative potential (for example, 17 to 20 kW) is input.

  Further, the cathode unit C includes a magnet unit Mu that is positioned on the atmosphere side (right side in FIG. 2) of the first support Cs1 and forms a magnetic field on the front left side of the sputtering surface Tp of the target T. The magnet unit Mu is composed of a plurality of magnets Mg arranged in a row on the side opposite to the sputtering surface Tp (on the right side of the target T) while changing the polarity of the target side. The magnet unit Mu itself can be of a known structure including the shape, number, and arrangement of magnets, and a detailed description thereof will be omitted here.

  A second support Cs2 serving as a lid for closing the other end opening 13b of the cylindrical body 1 is attached to the other end opening 13b of the cylindrical body 1, and the stage 2 is supported by the second support Cs2. Then, the substrate is set on the stage 2 with its film formation surface facing upward. Further, the stage 2 is connected to a driving shaft 31 of a driving means 3 such as a motor provided on the atmosphere side (lower side in FIG. 2) of the second support Cs2, and the stage 2, and thus the substrate W. Can be rotated at a predetermined rotational speed. It should be noted that the stage 2 may be connected to a high-frequency power source (not shown) so that a predetermined bias potential can be applied to the stage 2 and thus the substrate W during sputtering.

  A conductive plate-like member 4 is detachably provided in the cylindrical body 1 through an insulator (not shown) so as to cover the substantially entire inner peripheral surface. The plate-like member 4 is connected to another DC power source E2 as a power source, and is applied with a predetermined positive potential (for example, 50 to 150 V). In this case, the plate-like member 4 also serves as an adhesion preventing plate that prevents neutral and ionized sputtered particles from adhering to the inner surface of the cylindrical body 1. In the present embodiment, the plate-like member 4 and the DC power source E2 constitute a potential generating unit that converges the ionized sputtered particles toward the substrate W.

  A plurality of coils 5 formed by winding a conducting wire around a ring-shaped yoke made of a magnetic material are provided on the outer periphery of the cylindrical body 1 at predetermined intervals over the entire length of the cylindrical body 1. In this case, each coil 5 is supported by a column 51 erected on the outer peripheral surface of the cylindrical body 1. When each coil 5 is energized from a DC power source E3 having a known structure, the magnetic field lines correspond to the contour of the cylindrical body 1 between the target T and the substrate W and are perpendicular to the film formation surface of the substrate W. A magnetic field is generated so that Mf passes. In the present embodiment, each coil 5 and the DC power source E3 constitute a magnetic field generating means. Note that the number of coils 5 provided on the outer periphery of the cylindrical body 1 and the interval between the coils 5 are not limited to those shown in FIG. 2, but can generate a magnetic field as described above. If it is, there will be no restriction | limiting in particular, It can also comprise with a single coil.

  Further, a gas introduction pipe 6 for introducing a rare gas (sputtering gas) such as argon gas is connected to the cylindrical body 1, and the other end communicates with a gas source outside the figure via a mass flow controller 61. . The tubular body 1 is connected to an exhaust pipe 71 that communicates with a vacuum pump 7 such as a turbo molecular pump or a rotary pump.

Hereinafter, film formation by sputtering using the sputtering apparatus SM will be described. First, after setting the substrate W on the stage 2, the vacuum pump 7 is operated to evacuate the inside of the processing chamber 11 to a predetermined pressure (for example, 10 ⁻⁵ Pa). At this time, the coils 5 are not energized and do not generate a magnetic field (operation state where the magnetic field generating means is stopped). When the pressure in the processing chamber 11 reaches a predetermined value, argon gas is introduced into the processing chamber 11 at a predetermined flow rate, and predetermined power having a predetermined negative potential is applied to the target T from the DC power source E1. Thereby, plasma is formed between the target T in the processing chamber 11 and the substrate W. When the plasma is confined in the processing chamber 11 mainly by the magnetic field generated by the magnet unit Mu, the introduction of the sputtering gas is stopped and self-discharge is performed under a low pressure (so-called self-holding discharge).

  Next, the coil 5 is energized by the DC power source E <b> 3 to operate the magnetic field generation unit, corresponds to the outline of the cylindrical body 1 between the target T and the substrate W, and is applied to the film formation surface of the substrate W. A magnetic field is generated so that the magnetic field lines Mf pass vertically, and a predetermined positive potential (for example, 50 to 150 V) is applied to the plate-like member 4 by the DC power source E2. At this time, the stage 2 may be rotated at a predetermined rotational speed. Thereby, the ionized sputtered particles are changed in the direction along the magnetic field, and while being converged toward the substrate W, are incident on and deposited on the substrate W so as to be deposited and deposited.

  As described above, according to the present embodiment, the cylindrical body 1 has a curved portion so that the neutral sputtered particles scattered from the sputtering surface Tp of the target T do not reach the substrate W directly. Moreover, since each coil 5 is not energized until self-holding discharge, the neutral sputtered particles scattered from the sputtering surface Tp of the target T with a wide angle range hardly enter the substrate W and are ionized. Only the sputtered particles incident on the substrate W are substantially perpendicular to the substrate W, and are deposited and deposited. As a result, bottom coverage can be improved when the substrate W includes fine holes with a high aspect ratio. At this time, the provision of the potential generating means 4 and E2 increases the total amount of ionized sputtered particles incident on the substrate W, thereby improving the film formation rate and increasing the mass productivity. In addition, by rotating the stage 2 during film formation, the cylindrical body 1 has at least one curved portion 12, so that a gradient is generated in the magnetic field generated between the target T and the substrate W. Even in such a case, the in-plane uniformity of the film thickness distribution of the substrate W is not impaired.

  In order to confirm the above effects, the following experiment was performed using the sputtering apparatus SM of the above embodiment. The target T is made of copper having a composition ratio of 99.999%, and the cylindrical body 1 has a distance of 920 mm between the sputtering surface Tp of the target T and the film-forming surface of the substrate W, and from the sputtering surface Tp. What was curved in the L shape in the place of 600 mm was used. As sputtering conditions, an input power to the target T was 18 kW, Ar was used as a sputtering gas, and a sputtering gas was introduced at a flow rate of 10 sccm during film formation by sputtering. And the energization current to each coil 5 was changed stepwise between 0-20A, the film-forming rate to substrate W was measured, and the result is shown in FIG.

  According to this, when the energization current to each coil 5 is zero (that is, when the operation of the magnetic field generating means is stopped), copper is not formed on the substrate, and thereby, the sputtering surface Tp of the target T. It was confirmed that the neutral sputtered particles scattered from the substrate did not reach the substrate directly. When each coil 5 was energized, copper was deposited on the substrate W, and when the energization current was increased, the deposition rate increased. Thus, it was confirmed that only ionized sputtered particles can reach the substrate W to form a film.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above. In the above-described embodiment, the cylindrical body 1 has been described as an example having a single curved portion 12, but there may be a plurality of curved portions 12, and the curved portion of the present invention has a sputtering target T. This includes the case where the cylindrical body 1 is bent by 90 ° so that the surface Tp and the film formation surface of the substrate W are orthogonal to each other. In addition, when the cylindrical body 1 has the single curved part 12, it is inadequate only to bend so that the target T and the board | substrate W may not face, and it scatters from the target T with a wide angle range. In order to ensure that the neutral sputtered particles do not reach the substrate W, for example, it is necessary to appropriately design the distance from the curved portion 12 to both end openings 13a and 13b.

  Moreover, in the said embodiment, what comprised the plate-shaped member 4 provided in the cylindrical body 1 and the other DC power supply E2 as an example as an electric potential generation means to converge the ionized sputtered particle toward the board | substrate W. Although described, the present invention is not limited to this.

SM ... Sputtering device, 1 ... cylindrical body, 11 ... treatment chamber, 12 ... curved portion, 2 ... stage, 4 ... plate member (potential generating means), E2 ... DC power source (potential generating means), 6 ... gas introduction Tube (gas introduction means), Mf ... lines of magnetic force, T ... target, Tp ... sputter surface, W ... substrate.

Claims (7)

In a sputtering apparatus comprising: a processing chamber that is evacuated; a gas introduction unit that introduces a sputtering gas into the processing chamber; and a sputtering power source that supplies power to a target that faces the processing chamber.
The processing chamber is defined by a cylindrical body in which a target and a substrate to be processed are respectively disposed at openings at both ends, and the cylindrical body has at least one curved portion and introduces a sputtering gas into the processing chamber. The neutral sputtered particles scattered from the target when the target is powered on and sputtered are configured not to reach the substrate directly,
A magnetic field generating means for generating a magnetic field is provided around the cylindrical body so that a magnetic field line corresponding to the outline of the cylindrical body passes between the target and the substrate so that ionized sputtered particles reach the substrate. A sputtering apparatus characterized by that.   The sputtering apparatus according to claim 1, wherein the cylindrical body has an L-shaped outline.   The sputtering apparatus according to claim 1, wherein the cylindrical body further includes a potential generating unit that converges the ionized sputtered particles toward the substrate.   The said electric potential generation means is provided with the electroconductive plate-shaped member provided so that the inner surface of the said cylindrical body might be covered, and the power supply which applies a positive electric potential to a plate-shaped member. Sputtering equipment.   The sputtering apparatus according to claim 1, further comprising a stage that opens and holds one surface of the substrate and rotationally drives the substrate at a constant rotation speed. . In the sputtering method using the sputtering apparatus of any one of Claims 1-5,
The first step of introducing a sputtering gas into the evacuated processing chamber and supplying power to the target for sputtering while the magnetic field generating means that does not generate a magnetic field by the magnetic field generating means is stopped, and applying power to the target The second step of stopping the introduction of the sputtering gas while maintaining it, and the magnetic field generating means are operated to allow the ionized sputtered particles to reach the substrate and deposit and deposit the ionized sputtered particles on one surface of the substrate. And a third step of performing a sputtering method. The sputtering method according to claim 6, further comprising a step of operating a potential generating means in the third step to cause the ionized sputtered particles to converge toward the substrate.

Images