JP2011208185A - Sputtering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering apparatus which can achieve the film thickness uniformity in a plane and a high throughput with a small device with respect to a three-dimensional shape substrate, such as a via hole of high aspect and a lens having an irregularity shape lens.SOLUTION: The sputtering apparatus is composed of a vacuum vessel, a target disposed in the vacuum vessel, a gas adjustment means which exhausts air while introducing gas into the vacuum vessel, and a rotatable substrate holding base which is disposed opposing to the target and on which the substrate is placed, wherein by introducing a sputter gas or a reactive gas of the sputter gas, a target material or a reaction product of the target material can be piled up on the substrate with the target. The target is shifted against the substrate and disposed, and two or more ion generation mechanisms is disposed in which ion enters from vertical and oblique directions with respect to the substrate.

Description

  The present invention relates to a sputtering apparatus for forming a thin film on a substrate by sputtering.

  In the manufacturing process of a semiconductor integrated circuit (hereinafter referred to as IC), various metal and dielectric films are formed. For example, CVD, dry etching, sputtering, or the like is used as a film forming method. In recent years, miniaturization of ICs has progressed, and in order to cope with this, further miniaturization and three-dimensional semiconductor formation have been studied, and highly uniform film formation on high aspect vias is required. It has been.

Furthermore, in recent years, highly uniform formation of an optical thin film such as an antireflection film or an edge filter on a three-dimensional (uneven surface) lens has been studied in order to reduce the thickness of the lens and reduce the number of lenses. These optical devices usually have a low refractive index material (SiO ₂ , MgF, etc.) and a high refractive index material (Ta ₂ O ₅ , TiO ₂ , Nb ₂ O _5, etc.), and a material having an intermediate refractive index (Al ₂ O ₃ etc.), and in order that the optical film thickness (refractive index x physical film thickness) of each layer determines device characteristics, high film thickness uniformity and high film thickness controllability are required. . These optical thin films were mainly formed by vapor deposition, but formation by sputtering has been studied from the viewpoint of film quality.

  In recent years, diversification of needs has led to a reduction in the number of products in a variety of products, and there is a demand for conversion from large lot production to small lot production using a conventional large-sized apparatus. In addition, with the shortening of the product management cycle for the purpose of reducing the inventory of products, there is a demand for shortening the production lead time. In order to meet the above demands, high-quality, low-cost and efficient production using a small film forming apparatus using sputtering has been studied.

  FIG. 10 shows a schematic configuration diagram of a conventional magnetron sputtering apparatus. This time, the magnetron sputtering device for electrode formation for semiconductors is shown as an example. Hereinafter, this conventional sputtering apparatus will be described.

  In the conventional sputtering apparatus 90, a sputtering chamber is formed by a vacuum vessel 91 that can be evacuated, a target 92 is fixedly held on the lower electrode 93 above the vacuum vessel 91, and an earth shield 920 that is ground potential covers the outer periphery. ing. Further, an inner magnet 96 and an outer magnet 98 having a magnetization component opposite to the inner magnet 96 are arranged on the back surface of the target 92 so as to surround the inner magnet 96, and both magnets (96, 98) are magnetically coupled by a yoke 910. Has been. The magnets (96, 98) form arc-shaped lines of magnetic force 912 on the surface of the conductive target 92. The lower electrode 93 is electrically insulated from the container 91. The lower electrode 93 incorporates a water cooling mechanism (not shown) in order to prevent the temperature of the target 92 from rising.

  A substrate holder 914 is arranged below the vacuum vessel 91 in parallel with a distance of 50 mm so as to face the lower electrode 93. The substrate holder 914 is electrically insulated from the vacuum vessel 91 and has a floating potential. A substrate, for example, a semiconductor wafer (substrate 915) is placed on the substrate holder 914. The substrate holder 914 includes a cooling or heating mechanism (not shown) for maintaining the substrate 915 at a predetermined temperature.

  And predetermined DC electric power is given by the power supply 917 between the lower electrode 93 and the vacuum vessel 91.

  In order to perform the film forming process with the sputtering apparatus 90, the substrate 915 is placed on the substrate holder 914, and the vacuum chamber 91 is evacuated by a vacuum pump (not shown) connected to an exhaust port (not shown), Next, a variable conductance valve (not shown) interposed between the exhaust port and the vacuum pump while introducing a predetermined flow rate (for example, Ar gas) containing a reactive gas from a gas inlet (not shown). To adjust to a predetermined pressure. When it is necessary to ensure high in-plane uniformity, the substrate holder 914 is rotated by the substrate holder rotating mechanism 916 coupled to the substrate holder 914. Further, a substrate shutter 919 is provided on the substrate for preventing sputter particles from adhering to the substrate during dummy discharge before the main film formation.

Then, a negative DC voltage is applied to the target 92 to cause glow discharge and generate plasma. Electrons in the generated plasma are trapped by arc-shaped magnetic lines of force 912 generated by magnets (96, 98) disposed on the back surface of the target 92, further promoting ionization and improving the plasma density. The + ions (for example, Ar +, O ₂ +, etc.) in the generated plasma are attracted to the target 92 by a negative DC voltage, and the constituent atoms of the target 92 are sputtered. The sputtered particles sputtered from the target 92 are diffused and deposited on the substrate 915 in accordance with the cosine law. At this time, the sputtered particles adhere to members such as a deposition preventing plate in the sputtering apparatus 90. When a film is formed on a high aspect via, since there are few linear components, the film adheres to the surface of the via and the side surface in the vicinity of the via, and is difficult to form on the bottom of the via. In addition, it is difficult to form a highly uniform film even on an uneven lens for the above reason.

  On the other hand, in order to improve the straightness of the sputtered particles and promote film adhesion in the high aspect via, the following documents are disclosed.

  In Patent Documents 1 and 2, the ratio of the rectilinear component of the sputtered particles is increased by increasing the distance between the target and the substrate or arranging a collimator between the target and the substrate.

  Moreover, in patent document 3, it etches by ion shower irradiation from an ion generation mechanism simultaneously with sputtering film-forming, and modifies the surface.

JP-A-8-316147 JP 2004-256849 A JP-A-1-119665

  However, the methods of Patent Document 1 and Patent Document 2 increase the size and complexity of the apparatus and reduce the throughput.

  In the method of Patent Document 3, there is a large interference between the sputtering film formation and the ion generation mechanism, and it is difficult to process the surface in a highly uniform manner.

  The present invention solves the above-described conventional problems, and can perform highly uniform etching on a three-dimensional shape measurement object, and can perform production of a highly uniform film and highly efficient production. A device is provided.

  A sputtering apparatus according to the present invention includes a vacuum vessel, a target arranged in the vacuum vessel, a gas adjusting means for exhausting gas while introducing the gas into the vacuum vessel, and a substrate holder arranged facing the target A sputtering apparatus for forming a substrate held on the substrate holder by the target, wherein the center of the target and the center of the substrate holder are arranged to be shifted from each other perpendicularly and obliquely to the substrate. A plurality of ion generation mechanisms for irradiating ions are provided.

  The sputtering apparatus of the present invention has high in-plane uniformity with respect to a three-dimensional measurement object such as a high aspect via or convex / concave lens, and can realize highly uniform film formation and high efficiency production.

1 is a schematic configuration diagram of a magnetron sputtering apparatus according to a first embodiment of the present invention. The figure which shows the correlation of a board | substrate, a target, and an ion beam generator in the magnetron sputtering apparatus of this Embodiment 1. (A) Schematic diagram of etching only by sputtering film formation in the first embodiment, (b) Schematic diagram of a film adhesion shape in a via only by sputtering film formation in the first embodiment. (A) Schematic diagram of sputtering film formation and etching in ion beam generator 122 in the first embodiment, (b) Film deposition shape in via in sputtering film formation and ion beam generator 122 in the first embodiment. Schematic diagram of (A) Schematic diagram of sputtering film formation, ion beam generator 122 and ion beam generator 121 in Embodiment 1, and (b) Sputter film formation, ion beam generator 122 and ions in Embodiment 1. Schematic diagram of film adhesion shape in via in beam generator 121 In this Embodiment 1, the schematic diagram of the track | orbit of the ion beam by a magnetic field when not installing an adhesion prevention board In this Embodiment 1, the schematic diagram of the magnetic field interruption | blocking by the adhesion prevention board 123 installed in order to ensure the straightness of an ion beam The figure which showed the apparatus structure which made the inner side the distance of the adhesion prevention board 123 and the target 12 larger than the outer side. The figure which showed the apparatus structure which made the adhesion prevention board 123 slant so that the distance of the adhesion prevention board 123 and Cu target 12 may become large as the board | substrate 115 approaches. Schematic configuration diagram of a conventional magnetron sputtering system

(Embodiment 1)
FIG. 1 shows a schematic configuration diagram of a sputtering apparatus according to Embodiment 1 of the present invention. In the drawings, the xyz axis is shown in each figure in order to clarify the arrangement relationship.

  In this sputtering apparatus 10, a Si substrate 115 having a via pattern (not shown) having an opening diameter of 10 μm and a depth of 30 μm is put into a vacuum vessel 11, and a Cu thin film as a conductor is formed by sputtering. This is an example of a DC magnetron sputtering apparatus that performs etching using an ion beam.

  A rectangular Cu target 12 and a lower electrode 13 having an outer diameter of 300 mm × 100 mm are disposed below the vacuum vessel 11, and a Si substrate 115 is disposed at a distance of 100 mm between the target 12 and the substrate 115. Here, the distance between the center of the substrate tray 114 and the center of the target is 70 mm. An earth shield 120 having a ground potential is disposed on the outer periphery of the target 12. In addition, the vertical incidence ion beam generator 121 having a radius of 100 mm was shifted 70 mm from the center of the substrate 115 to the opposite side of the target 12, and the distance from the substrate 115 was arranged at a height of 100 mm. The ion beam generator (ion generation mechanism) 121 is movable so as to be set at an optimum angle with respect to the substrate 115. As shown in FIG. 2, the ion beam generator 122 for oblique incidence having a radius of 100 mm is shifted 90 mm from the center of the substrate 115 to the opposite side of the target 12, and is further shifted by 45 ° in the circumferential direction with the center of the substrate 115 as the center. The substrate 115 was inclined at 30 ° with respect to the substrate 115 and placed at a height of 50 mm from the substrate 115. Further, two deposition plates 123 and 124 are disposed between the target 12 and the ion beam generator 121.

  The adhesion prevention plate 123 on the target 12 side is made of a magnetic material SPCC excellent in workability, and the distance between the bottom side and the substrate 115 is set to 50 mm. Further, the adhesion preventing plate 124 made of low-cost non-magnetic SUS304 was installed at a distance of 70 mm between the bottom and the substrate 115.

The vacuum vessel 11 was evacuated to 5 × 10 ⁻⁴ Pa by a turbo molecular pump (not shown) and a rotary pump (not shown), and then Ar gas was introduced at 50 sccm. The pressure inside the vacuum vessel 11 was kept constant at 0.5 Pa by adjusting a variable conductance valve (not shown).

  Next, the substrate 115 was rotated, and 3 kW of power was applied to the lower electrode 13 on the back surface of the target 12 by the DC pulse power source 117. Thereby, glow discharge is generated on the target 12, and sputtering can be started. At the same time, the ion beam generators 121 and 122 set the applied voltage to 500 V and the current to 20 mA, and the substrate 115 was irradiated with the ion beam to perform etching.

  FIGS. 3A and 3B show the shape of the film attached to the via 125 on the substrate 115 only by sputtering film formation. The vias 125 are holes formed in a plurality of arbitrary shapes and arrangements on the surface of the substrate 115 as shown in FIG. Since the target 12 is displaced with respect to the substrate 115, the via 125 on the substrate outer side 115b is less biased on the inner side and the outer side of the inner surface of the via, but the via 125 on the inner side 115a is on the inner side of the inner surface of the via. The outside is thinner.

  Here, FIGS. 4A and 4B are schematic diagrams of etching only by oblique incidence by the ion beam generator 122. FIG. Due to the oblique incidence, only the surface of the substrate 115 and the inside of the via inner surface are etched. The vias 125 on the substrate inner side 115a are uniform, but the vias 125 on the substrate outer side 115b are etched only on the inner side of the inner surface of the via. Further, FIGS. 5A and 5B show schematic views of etching in which an ion beam generator 121 is added. When the ion beam generator 121 is horizontally disposed, the film to which the surface of the substrate 115 and the bottom surface in the via are attached is etched. When the ion beam generator 121 is inclined 15 ° in the outer direction of the substrate 115, the surface of the substrate 115 and the outer side of the via inner surface of the substrate outer surface 115b are etched. Due to the above effects, in the present invention, a uniform film can be formed in the surface and in the via.

  Further, by making the deposition plate 123 installed between the target 12 and the ion beam generator 121 a magnetic material, the magnetic field from the magnets 16 and 18 is blocked, and the ion beam can be bent by the magnetic field. This can prevent the target portion from being etched efficiently. FIG. 6 shows a schematic diagram when there is no deposition plate 123, and FIG. 7 shows a schematic diagram when there is a deposition plate 123.

  Furthermore, by applying a positive potential to the deposition plates 123 and 124 installed between the target 12 and the ion beam generator 121, interference between positive ions in the plasma and the ion beam can be reduced. In order to prevent the positive ions in the plasma from diffusing into the ion beam, +20 V, which is 10% or less of the discharge voltage, was applied to the deposition preventing plate 123. At that time, the applied voltage is controlled independently by the double deposition plates, the applied voltage to the deposition plate 124 is made smaller than the voltage applied to the plasma deposition plate 123, and the deposition plate By disposing 124 at a position farther from the substrate 115 side than the deposition preventing plate 123, it is possible to suppress the ion beam having a positive potential from being repelled and greatly bent by the deposition preventing plate 124 to which a positive potential is applied. Can irradiate places.

  For the reasons described above, +10 V was applied to the deposition preventing plate 124. At this time, a sufficient effect can be obtained if the voltage applied to the deposition preventing plate 124 is set to 5% or less of the voltage applied to the ion beam generator 121 and smaller than the voltage applied to the deposition preventing plate 124.

  Further, if the applied voltage to the deposition preventing plate 123 is 10% or more of the discharge voltage, the influence on the plasma becomes large and the discharge becomes non-uniform, so that the applied voltage to the deposition preventing plate 123 is sufficient. 5% to 10% of the discharge voltage at which an effect is obtained is desirable.

  The arrangement of the substrate 115 and the adhesion preventing plates 123 and 124 is preferably set so that the adhesion preventing plate 123 does not interfere with the substrate shutter 119 and is not less than 30 mm from the substrate 115 and not more than 50 mm capable of sufficiently blocking the magnetic field and plasma. In this embodiment, the thickness is 50 mm. Further, the deposition preventing plate 124 is set apart from the substrate 115 by 70 mm, which is a sufficient distance to reduce the influence on the ion beam generator 121. Further, in order to insulate the adhesion preventing plates 123 and 124, an insulator such as Teflon (registered trademark) or ceramic may be inserted between them.

  Furthermore, the potential applied to the deposition plate 124 in the vicinity of the substrate 115 or the sputter cathode is formed by making the deposition plate 123 made of a magnetic material having a small potential longer in the direction of the substrate 115 than the deposition plate 124 having a large potential. The ion beam is prevented from being bent by the magnetic field.

  Furthermore, as shown in FIG. 8, the distance between the deposition preventing plate 123 and the target 12 is made larger on the inner side of the target 12 than on the outer side of the target 12, so that the film adhesion amount on the deposition preventing plate 123 is uniform. be able to.

  Further, as shown in FIG. 9, the deposition amount of the film can be reduced by making the deposition preventing plate 123 slant so that the distance between the deposition preventing plate 123 and the target 12 becomes closer to the substrate 115.

  Furthermore, by applying a negative potential to the substrate holder 114, the energy / straightness of the ion beam can be further improved, and the etching rate can be improved and the shape can be optimized.

  Furthermore, the same effect as that of the present invention can be obtained by using an ion generation mechanism such as an ion shower other than the ion beam.

  Furthermore, the same effects as those of the present invention can be obtained by optimizing the film formation conditions for sputtering film formation, the apparatus configuration, the ion species of the ion beam, the irradiation conditions, and the intermittent irradiation method depending on the substrate shape and the required specifications.

  As described above, by arranging a target and a plurality of ion generation mechanisms in one vacuum vessel, and simultaneously etching a plurality of ion generation mechanisms from a vertical direction and an oblique direction while forming a sputtering film, With respect to a three-dimensional substrate such as an uneven lens, high in-plane film thickness uniformity and high throughput can be achieved with a small apparatus. As a result, it was possible to provide a small sputtering apparatus that can achieve high uniformity and improved productivity.

  The sputtering apparatus according to the present invention can achieve high in-plane film thickness uniformity and high throughput with a small apparatus on a three-dimensional substrate such as a high aspect via or an uneven lens. This is useful as a method for forming a thin film.

10, 90 Sputtering apparatus 11, 91 Vacuum vessel 12, 92 Target 13, 93 Lower electrode 16, 18, 96, 98 Magnet 110, 910 Yoke 112, 912 Magnetic field lines 114, 914 Substrate holder 115, 915 Substrate 116, 916 Substrate holder rotation Mechanism 117, 917 Power source 119, 919 Substrate shutter 120, 920 Earth shield 121, 122 Ion beam generator 123, 124 Attachment plate

Claims (8)

A vacuum vessel, a target arranged in the vacuum vessel, a gas adjusting means for exhausting gas while introducing gas into the vacuum vessel, and a substrate holder arranged to face the target. In a sputtering apparatus for forming a substrate held by the substrate holder,
The center of the target and the center of the substrate holder are shifted from each other,
A sputtering apparatus comprising a plurality of ion generating mechanisms for irradiating ions from perpendicular and oblique directions with respect to the substrate. The sputtering apparatus according to claim 1, wherein an adhesion preventing plate to which a positive potential is applied is disposed between the target and the ion generation mechanism. The sputtering apparatus according to claim 2, wherein the deposition preventing plate is made of a magnetic material or a magnetic material formed on a surface thereof. The deposition preventing plate is composed of a first deposition preventing plate and a second deposition preventing plate, and has a higher positive potential applied to the second deposition preventing plate on the ion generating mechanism side than the first deposition preventing plate on the target side. The sputtering apparatus according to claim 2, wherein: The said adhesion prevention board is comprised from the 1st adhesion prevention board and the 2nd adhesion prevention board, and the distance with the board | substrate holder of the 2nd adhesion prevention board by the side of the said ion generating mechanism is more than the 1st adhesion prevention board by the side of a target. The sputtering apparatus according to claim 2, wherein the sputtering apparatus is large. The surface of the deposition preventing plate is a curved surface, and the distance between the deposition preventing plate and the target is larger on the inner side of the target than on the outer side of the target. The sputtering apparatus as described. The sputtering apparatus according to claim 2, wherein the distance between the deposition preventing plate and the target increases as the distance from the substrate approaches. The sputtering apparatus according to claim 2, wherein a negative potential is applied to the substrate holder.

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