JP2007186726A - Sputtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a sputtering apparatus using an AC power source in such a manner that electric power can be applied with high precision without depending on the distance between the installation place thereof and the installation place of the AC power source. <P>SOLUTION: The inside of a vacuum chamber 11 is provided with: a pair of targets 41a, 41b; and an AC power source E of applying voltage to the pair of targets in such a manner that polarities are alternately changed. The AC power source E is composed so as to be divided into a power feed part 6 of enabling the feed of power and an oscillation part 7 having a switch circuit 72 for oscillation connected to a power line from the power feed part, and the oscillation part and each target are connected by a busbar 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sputtering apparatus capable of forming a film on the surface of a processing substrate, and more particularly to a sputtering apparatus using an AC power source.

  In the sputtering method, ions in a plasma atmosphere are accelerated and bombarded toward a target formed in a predetermined shape according to the composition of a film to be formed on the surface of the processing substrate, and target atoms are scattered, thereby processing the substrate surface. A thin film is formed. In this case, a glow discharge is generated between the cathode electrode and the anode electrode or the earth electrode by applying a voltage to the target, which is a cathode electrode, via a sputtering power source such as a DC power source or an AC power source, thereby creating a plasma atmosphere. In particular, when an AC power supply is used, a stable discharge can be obtained by applying the opposite phase voltage to cancel the charge accumulated on the cathode surface.

For this reason, a pair of targets are arranged in the vacuum chamber, and a voltage is applied to the pair of targets by alternately changing the polarity at a predetermined frequency via an AC power source, and each target is applied to the anode electrode and the cathode electrode. It is known to alternately switch to generate a glow discharge between the anode electrode and the cathode electrode to form a plasma atmosphere and to sputter each target (for example, Patent Document 1).
International Publication WO2003 / 14410 (see, for example, claim 1).

  In the above, an AC power source including an oscillation unit for outputting (powering on) AC power to a pair of targets is used. In general, the AC power source and each target are connected via a known AC power cable formed by twisting a large number of conducting wires, for example. In this case, due to the skin effect when an alternating current is passed, the effective cross-sectional area of the conductor decreases and the alternating current resistance increases and the conductor loss increases as the frequency of the alternating current power supply increases. It is easy to cause a loss of power input to the power source, and the power waveform of power input to the pair of targets is likely to be disturbed due to the influence of noise. This becomes more conspicuous as the distance between the installation location of the sputtering apparatus main body and the installation location of the AC power supply becomes longer. As a result, there is a problem that power cannot be input to a pair of targets with high accuracy.

  Accordingly, in view of the above points, the present invention has an object to provide a sputtering apparatus that can accurately input power without depending on the distance between the installation place of the sputtering apparatus main body and the installation place of the AC power supply. To do.

  In order to solve the above problems, a sputtering apparatus of the present invention includes a pair of targets provided in a vacuum chamber, and an alternating current power source that alternately applies a polarity to the pair of targets at a predetermined frequency and applies a voltage. The AC power supply is divided into a power supply unit capable of supplying power and an oscillation unit having an oscillation switch circuit connected to a power line from the power supply unit, and the oscillation unit and Each target is connected by a bus bar.

  According to the present invention, since the power supply unit and the oscillating unit are configured separately, only the oscillating unit that outputs AC power can be arranged so that the distance between the pair of targets is kept at a constant short distance. . In addition, since the oscillating portion and each target are connected by a bus bar, the surface area of the portion where the alternating current flows is large, and a large current can flow without being affected by the skin effect. As a result, compared to the use of a known AC power cable, it is difficult to cause a loss of input power, and moreover, it is difficult to be affected by noise. As a result, power can be input to the pair of targets with high accuracy from the AC power supply.

  In this case, if the bus bar has its surface covered with a thin film of Au or Ag, when AC power is applied, only the portion where the AC current flows is made of a highly conductive material, thereby reducing the cost. It may be possible to plan.

  If the bus bar is made to be extendable and retractable, an error in the distance between the oscillating portion and the target can be absorbed when the bus bar is attached, and the bus bar can be attached easily.

  Further, in order to maintain the distance between the oscillation unit that outputs AC power and each target at a certain short distance, the casing of the oscillation unit may be attached to the outer wall of the vacuum chamber.

  In addition, a plurality of pairs of targets are arranged in parallel in the vacuum chamber, and an AC power source is provided for each pair of targets, and is provided at the rear of each target so as to form a magnetic flux in front of each target. In the case where a magnet assembly composed of a plurality of magnets arranged in a different manner is arranged, each pair of targets can be powered with high accuracy from an AC power source, so that each target is sputtered evenly to form a good film. It becomes possible.

  In this case, if a driving means for integrally driving each magnet assembly is provided so that the magnetic flux is movable in parallel with respect to the target, each target may be eroded equally.

  As described above, the sputtering apparatus of the present invention is less susceptible to the loss of input power and noise, can accurately power on the target, and further eliminates the need for an expensive AC power cable, thereby reducing costs. There is an effect.

  Referring to FIG. 1, reference numeral 1 denotes a magnetron sputtering apparatus (hereinafter referred to as “sputtering apparatus”) of the present invention. The sputtering apparatus 1 is of an in-line type using an AC power supply so that a stable discharge can be obtained by applying an opposite phase voltage to cancel charges accumulated on the target surface described later. The sputtering apparatus 1 has a vacuum chamber 11 that can be maintained at a predetermined degree of vacuum via vacuum exhaust means (not shown) such as a rotary pump or a turbo molecular pump. A substrate transfer means is provided in the upper part of the vacuum chamber 11. The substrate transport unit has a known structure, and has, for example, a carrier 2 on which the process substrate S is mounted, and can sequentially transport the process substrate S to a position facing the target by intermittently driving the drive unit.

A gas introducing means 3 is provided in the vacuum chamber 11. The gas introduction means 3 communicates with a gas source 33 through a gas pipe 32 provided with a mass flow controller 31, and O ₂ , H ₂ O, H ₂ , used for sputtering gas such as Ar, or reactive sputtering. A reactive gas such as N ₂ can be introduced into the vacuum chamber 11 at a constant flow rate. A cathode electrode C is disposed below the vacuum chamber 11.

  The cathode electrode C has a pair of targets 41a and 41b disposed to face the processing substrate S. Each target 41a, 41b is manufactured by a known method according to the composition of a thin film to be formed on the processing substrate S, such as Al, Ti, Mo, or ITO, and is formed in a substantially rectangular parallelepiped (rectangular in a top view). Yes. Each target 41a, 41b is joined to a backing plate 42 for cooling the target 41a, 41b during sputtering through a bonding material such as indium or tin, and is attached to the frame of the cathode electrode C through an insulating material (not shown). In the vacuum chamber 11, it is arranged in a floating state.

  In this case, the targets 41a and 41b are juxtaposed so that the unused sputtering surface 411 is located on the same plane parallel to the processing substrate S, and between the opposing side surfaces 412 of the targets 41a and 41b. Does not have any components such as an anode or a shield. The external dimensions of the targets 41a and 41b are set to be larger than the external dimensions of the processing substrate S when the targets 41a and 41b are arranged side by side.

  Further, the cathode electrode C is equipped with a magnet assembly 5 positioned behind each of the targets 41a and 41b. The magnet assembly 5 includes a support plate 51 provided in parallel with the targets 41a and 41b. The support plate 51 is made of a rectangular flat plate formed so as to extend to both sides of the targets 41a and 41b along the longitudinal direction of the targets 41a and 41b. The support plate 51 amplifies the magnet's adsorption force. Made of magnetic material. On the support plate 51, rod-shaped central magnets 52 along the longitudinal direction of the targets 41a and 41b and peripheral magnets 53 provided along the outer periphery of the support plate 51 are provided with alternating polarities. In this case, the volume when converted to the same magnetization of the central magnet 52 is, for example, equal to the sum of the volumes when converted to the same magnetization of the peripheral magnet 52 (peripheral magnet: center magnet: peripheral magnet = 1: 2: 1). It is designed to be.

  Thereby, balanced closed-loop tunnel-shaped magnetic fluxes are formed in front of the targets 41a and 41b, respectively, and the ions ionized in front of the targets 41a and 41b and the secondary electrons generated by sputtering are captured. The plasma density can be increased by increasing the electron density in front of each of 41a and 41b. In addition, an AC power source E is provided so that a voltage can be applied to the pair of targets 41a and 41b by alternately changing the polarity at a predetermined frequency (1 to 400 KHz).

  By the way, when power is supplied to the pair of targets 41a and 41b using the AC power source E, the input power is not lost, and it is difficult to be affected by noise, so that the set power can be input with high accuracy. There is. In the present embodiment, the AC power supply E is divided into the power supply unit 6 that can supply power and the oscillation unit 7 that alternately changes the polarity at a predetermined frequency and outputs a voltage to each of the targets 41a and 41b. The casing 70 of the oscillating unit 7 is attached to the bottom wall of the vacuum chamber 11, and the oscillating unit 7 and the targets 41a and 41b are connected by a bus bar 8 having a predetermined length as will be described later. . In this case, the waveform of the output voltage is a sine wave, but is not limited thereto, and may be a square wave, for example.

  As shown in FIG. 2, the power supply unit 6 has a box-shaped casing 60, and a first CPU circuit 61 that controls the operation of the casing 60 and commercial AC power (three-phase AC 200 V). Or an input unit 62 to which 400V) is input, and six diodes 63 that rectify the input AC power and convert it to DC power, and oscillate DC power through DC power lines 64a and 64b. 7 plays the role of outputting.

  Further, a switching transistor 65 is provided between the DC power lines 64a and 64b, and is connected to the first CPU circuit 61 so as to be communicable. The first driver circuit 66a and the second driver circuit 66a for controlling on / off of the switching transistor 65 are provided. 1 PMW control circuit 66b is provided. In this case, a detection circuit 67a and an AD conversion circuit 67b are provided which have a current detection sensor and a voltage detection transformer and detect the current and voltage between the DC power lines 64a and 64b, and are provided via the detection circuit 67a and the AD conversion circuit 67b. Are input to the CPU circuit 61.

  On the other hand, the oscillating unit 7 has a box-shaped housing 70 and is attached to the outer wall below the vacuum chamber 11. In the housing 70, there are four second CPU circuits 71 communicably connected to the first CPU circuit 61 and four switch circuits 72 constituting an oscillation switch circuit 72 provided between the DC power lines 64a and 64b. The first to fourth switching transistors 72a, 72b, 72c, 72d and a second driver that is connected to the second CPU circuit 71 so as to be communicable and controls the on / off of each of the switching transistors 72a, 72b, 72c, 72d. A circuit 73a and a second PMW control circuit 73b are provided.

  Then, by the second driver circuit 73a and the second PMW control circuit 73b, for example, on and off timings of the first and second switching transistors 72a and 72b and the third and fourth switching transistors 72c and 72d. When the operations of the switching transistors 72a, 72b, 72c, 72d are controlled so as to be inverted, sinusoidal AC power can be output via the AC power lines 74a, 74b from the oscillation switch circuit 72. In this case, a detection circuit 75a and an AD conversion circuit 75b for detecting an oscillation voltage and an oscillation current are provided, and are input to the second CPU circuit 71 via the detection circuit 75a and the AD conversion circuit 75b.

  The AC power lines 74a and 74b are connected to an output transformer 76 having a known structure via a resonance LC circuit in series, parallel, or a combination thereof, and output terminals 76a and 76b from the output transformer 76 and a pair of targets. The bus bars 8 are connected to 41a and 41b. In this case, a detection circuit 77a and an AD conversion circuit 77b are provided, which have a current detection sensor and a voltage detection transformer, and detect an output voltage and an output current to the pair of targets 41a and 41b. To be input to the second CPU circuit 71 via. This makes it possible to apply a constant voltage to the pair of targets 41a and 41b while changing the polarity alternately at a constant frequency via the AC power source E during sputtering.

  The output from the detection circuit 77a is connected to a detection circuit 78a that detects the output phase and frequency of the output voltage and output current, and through an output phase frequency control circuit 78b that is communicably connected to the detection circuit 78a. Thus, the phase and frequency of the output voltage and output current are input to the second CPU circuit 71. Thus, the on / off of each switching transistor 72a, 72b, 72c, 73d of the oscillation switch circuit 72 is controlled by the second driver circuit 73a by the control signal from the second CPU circuit 71, and the output voltage and output current are controlled. Can be controlled so that their phases substantially coincide with each other.

  As shown in FIG. 3, the bus bar 8 is configured by connecting attachment portions 81 and 82 to both sides of a plate-like central portion 81 via fastening means including bolts B and nuts N, respectively. The central portion 81 and the mounting portions 82 and 83 are preferably made of the same material having high conductivity, and are made of, for example, Cu, Au, Ag, or an aluminum alloy.

  In this case, the surface area and the plate thickness of the central portion 81 are the material of the plate material constituting the central portion 81, the input power to the targets 41a and 41b when performing the film forming process using the sputtering apparatus 1, the frequency of the alternating current power, etc. (For example, when the length of the central portion 81 is about 300 mm and the width is 40 mm, the plate thickness is set to 6 mm). On the other hand, the attachment portions 82 and 83 are wider than the plate material of the central portion 81 in consideration of attachment to the output terminals 76a and 76b provided on the output side of the output transformer 76 of the oscillation portion 7 and the targets 41a and 41b. The plate material is configured to be bent in a substantially Z shape in cross-sectional view, and output terminals 76a and 76b and each target 41a are connected by fastening means (not shown) such as bolts through mounting holes 82a and 83a provided at one end thereof. , 41b.

  In addition, two through holes 81a, 82b, and 83b are formed at both ends of the central portion 81 and the other ends of the mounting portions 82 and 83, respectively, and the through holes 81a, 82b, and 83b are aligned in the vertical direction. Then, both ends of the central portion 81 and one ends of the mounting portions 82 and 83 are overlapped with each other, and the shaft portion of the bolt B is inserted into each of the through holes 81a, 82b, and 83b, and then a nut N is fastened to the other end. Are connected to each other. In this case, the through hole 82b of one attachment portion 82 is formed as a long hole, and the length of the bus bar 8 itself can be adjusted according to the distance between the output terminals 76a and 76b and the targets 41a and 41b. That is, the bus bar 8 can be extended and contracted. Thereby, the error of the space | interval between the oscillation part 7 and target 41a, 41b can be absorbed, and the attachment operation | work of the bus bar 8 can be made easy.

  When the bus bar 8 is mounted between the output terminals 76a and 76b and the targets 41a and 41b, the central portion 81 penetrating the support plate 51 is exposed. Covered by material 9.

  Thereby, the surface area of the part through which the alternating current flows is large, and a large current can flow without being affected by the skin effect. As a result, compared to the use of a known AC power cable, it is possible to make it difficult to cause a loss of input power and to be less susceptible to noise. it can.

  Then, the processing substrate S is transferred to a position facing the pair of targets 41 a and 41 b by the substrate transfer means, and a predetermined sputtering gas is introduced through the gas introduction means 3. An AC voltage is applied to the pair of targets 41a and 41b via the AC power source E, and the targets 41a and 41b are alternately switched between the anode electrode and the cathode electrode, and a glow discharge is generated between the anode electrode and the cathode electrode to generate a plasma atmosphere. Form. As a result, ions in the plasma atmosphere are accelerated and bombarded toward one of the targets 41a and 41b that have become cathode electrodes, and target atoms are scattered to form a thin film on the surface of the processing substrate S.

  In this case, the magnet assembly 5 is provided with driving means such as a motor (not shown), and is reciprocated between the two positions along the horizontal direction of the targets 41a and 41b in parallel and at a constant speed by the driving means. In addition, the erosion area is obtained uniformly over the entire surface of the targets 41a and 41b.

  In the present embodiment, the bus bar 8 has been described in which two mounting portions 82 and 83 are connected to both sides of the central portion 81. However, the present invention is not limited to this, and the bus bar 8 is manufactured integrally. Also good. Moreover, although it was made of a material having high conductivity, when AC power is applied, only the portion where the AC current flows is made of a material having high conductivity such as Au or Ag, that is, the surface of the bus bar 8 is made Au. Alternatively, it may be covered with a thin film of Ag or Ag so as to reduce the cost.

  In the present embodiment, the case where the pair of targets 41a and 41b are provided in the vacuum chamber 11 has been described. However, the present invention is not limited to this, and as shown in FIG. A plurality of targets 41a to 41f are arranged side by side, and AC power sources E1 to E3 having the same structure are allocated to the targets 41a to 41f adjacent to each other, and a plurality of pairs of targets are connected via the AC power sources E1, E2, and E3. The present invention can also be applied to devices in which the sputtering apparatus is configured so that power can be input to 41a to 41f. In this case, AC power is supplied to each of the targets 41a to 41f from different AC power supplies E1 to E3, but each of the pair of targets 41a to 41f can be supplied with high accuracy from each of the AC power supplies E1 to E3 (each AC power supply). Therefore, the targets 41a to 41f can be sputtered evenly to achieve good film formation.

1 is a diagram schematically illustrating a sputtering apparatus of the present invention. The figure explaining the structure of alternating current power supply. The disassembled perspective view explaining the structure of a bus bar. The figure explaining roughly the modification of the sputtering device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sputtering apparatus 11 Vacuum chamber 41a, 41b Target 6 Power supply part 7 Oscillation part
8 Busbar E AC power supply

Claims (6)

A pair of targets provided in the vacuum chamber, and an alternating current power source for alternately applying a polarity to the pair of targets at a predetermined frequency and applying a voltage, the alternating current power source is capable of supplying power A sputtering apparatus comprising: a supply unit; and an oscillation unit having an oscillation switch circuit connected to a power line from the power supply unit, wherein the oscillation unit and each target are connected by a bus bar. . The sputtering apparatus according to claim 1, wherein the bus bar has a surface covered with a thin film of Au or Ag. The sputtering apparatus according to claim 1, wherein the bus bar is extendable. The sputtering apparatus according to claim 1, wherein a housing of the oscillation unit is attached to an outer wall of a vacuum chamber. A plurality of pairs of targets are arranged side by side in the vacuum chamber, and an AC power source is provided for each pair of targets, provided behind each target so as to form a magnetic flux in front of each target, and alternately changing the polarity. The sputtering apparatus according to claim 1, wherein a magnet assembly including a plurality of provided magnets is disposed. The sputtering apparatus according to claim 5, further comprising a driving unit that integrally drives the magnet assemblies so that the magnetic flux is movable in parallel with respect to the target.

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