JP2004169127A - Ecr sputtering apparatus and method for forming multilayer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ECR sputtering apparatus capable of forming a plurality of kinds of thin films. <P>SOLUTION: The ECR sputtering apparatus forms a multilayer film on a substrate S by generating a plasma by electron cyclotron resonance and sputtering targets 11A, 11B with ions 21 in the generated plasma. A plurality of targets 11A, 11B are placed in a film formation chamber 3. In forming one layer of the multilayer film, a bias voltage from a DC bias power source 12A is applied to target 11A; at that time, the bias voltage on target 11B is cut off and a shutter 20 is closed. On the other hand, in forming the other layer, the bias voltage is applied to target 11B; at that time, the bias voltage on target 11A is cut off and the shutter 20 is closed. Such operations are repeated to form the multilayer film. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ECR (Electron Cyclotron Resonance) sputtering apparatus used for forming a multilayer film in manufacturing a hard disk head, an optical filter used for optical communication, a sense layer of an MRAM, a dielectric multilayer filter, and the like, and an apparatus therefor. The present invention relates to a method for forming a multilayer film using the method.
[0002]
[Prior art]
In an ECR sputtering apparatus, a magnetic field is formed in a plasma generation chamber in an argon atmosphere, and a microwave is introduced from a microwave introduction window, thereby generating plasma using electron cyclotron resonance (ECR). Then, argon ions in the generated plasma are made incident on a target to emit sputtered particles, and the sputtered particles are deposited on a substrate to form a thin film made of a target material (for example, see Patent Document 1). ).
[0003]
In a conventional ECR sputtering apparatus, one kind of thin film layer is formed in a film forming chamber using one kind of target electrode. Therefore, when forming a multilayer film composed of a plurality of thin film layers, for example, a plurality of film forming chambers each having a target corresponding to the type of the film are provided, such as an in-line sputtering apparatus, and a substrate is formed every time one layer is formed. Had to be transferred between the film forming chambers. (For example, see Patent Document 2). Further, a multi-chamber configuration in which a plurality of film formation chambers are connected to the transfer chamber and the substrate is transferred between the film formation chambers via the transfer chamber every time one layer is formed is also conceivable.
[0004]
[Patent Document 1]
JP-A-10-219445 [Patent Document 2]
JP-A-6-158305
[Problems to be solved by the invention]
However, in the conventional apparatus as described above, a substrate transport operation is required every time each layer of the multilayer film is formed. Therefore, in a dielectric multilayer filter or the like that requires a multilayer film including 100 to 200 layers or more, In addition, there is a problem that a wasteful transfer time that does not contribute to film formation becomes enormous. Further, since a film forming chamber must be provided in accordance with the number of film types, there is a disadvantage that the cost of the sputtering apparatus increases and the area occupied by the apparatus becomes enormous.
[0006]
An object of the present invention is to provide an ECR sputtering apparatus capable of forming a plurality of types of thin films and a multilayer film forming method using the apparatus.
[0007]
[Means for Solving the Problems]
(1) An ECR sputtering apparatus according to the first aspect of the present invention generates plasma by electron cyclotron resonance, and sputters a target with ions in the generated plasma to form a plurality of types of thin films on a substrate. A plurality of targets provided in accordance with a plurality of types of thin films, a bias power supply for individually applying a bias voltage to the plurality of targets, and a target provided for the thin film when forming the thin film. And a controller that controls a bias power supply so that a bias voltage is applied to the target, and controls the bias voltage applied to the target by the controller to form a thin film arbitrarily selected from a plurality of types of thin films. Thereby, the above object is achieved.
(2) According to a second aspect of the present invention, in the ECR sputtering apparatus according to the first aspect, a shielding means for covering a sputtering surface of a target to which no bias voltage is applied and for preventing incidence of sputter particles is provided. .
(3) The invention of claim 3 is a multilayer film forming method for forming a multilayer film on a substrate using the ECR sputtering apparatus according to claim 1 or 2, wherein a via voltage is sequentially applied to a plurality of targets. Then, the above object is achieved by sequentially forming the layers constituting the multilayer film.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing an embodiment of an ECR sputtering apparatus according to the present invention. The ECR sputtering apparatus 1 includes a plasma generation chamber 2 for generating plasma, and a film formation chamber 3 in which a substrate S on which a film is to be formed is stored. A control device 15 controls the entire apparatus. The plasma generation chamber 2 and the film formation chamber 3 communicate with each other through a plasma extraction opening 4, and are evacuated by a vacuum pump 10. An air-core coil 5 for generating a magnetic field is provided around the plasma generation chamber 2. The coil 5 forms a magnetic field (87.5 mT) satisfying the ECR condition in the plasma generation chamber 2 and also forms a divergent magnetic field for guiding the plasma to the film formation chamber 3 through the opening 4.
[0009]
Reference numeral 6 denotes a microwave source which generates a microwave of 2.45 GHz. The microwave generated by the microwave source 6 is guided to the plasma generation chamber 2 by the waveguide 7, and is introduced into the plasma generation chamber 2 through the quartz glass microwave introduction window 8 provided in the plasma generation chamber 2. The plasma generation chamber 2 is configured to function as a cavity resonator for microwaves of 2.45 GHz. Reference numeral 9 denotes a gas supply device that supplies an argon gas for plasma generation to the plasma generation chamber 2.
[0010]
When a magnetic field of 87.5 mT is generated in the plasma generation chamber 2 in an argon atmosphere and microwaves of 2.45 GHz are introduced from the microwave introduction window 8, argon gas is ionized by ECR and high-density plasma is generated. . The plasma in the plasma generation chamber 2 is drawn from the opening 4 to the film formation chamber 3 along the lines of magnetic force 13 of the divergent magnetic field formed by the coil 5. At this time, the distribution of the plasma drawn into the film forming chamber 3 is substantially rotationally symmetric with respect to the center axis J of the opening 4.
[0011]
The ECR sputtering apparatus 1 shown in FIG. 1 shows a configuration in which two types of layers a and b are alternately formed on a substrate S to form a multilayer film. When the a layer is formed, the film is formed using the target 11A, and when the b layer is formed, the film is formed using the target 11B. Reference numerals 12A and 12B denote DC bias power supplies, which operate the DC bias power supplies 12A and 12B in a voltage control mode to apply a bias potential to each of the targets 11A and 11B independently. On / off of the applied voltage to the targets 11A and 11B is performed by controlling the on / off of the switches SWa and SWb by the control device 15.
[0012]
The DC bias power supplies 12A and 12B are variable power supplies, and can independently set the voltage according to the target members used for the targets 11A and 11B. As the DC bias power supplies 12A and 12B, those which generate a pulsed DC voltage for the purpose of reducing the occurrence of arcing are desirable, but those which continuously supply a constant DC voltage may be used. Note that the DC power supply may be controlled in the voltage control mode or in the current control mode.
[0013]
The substrate S is held by the substrate stage 14. A shutter 23 is provided in front of the substrate S. The shutter 23 is opened as shown by a two-dot chain line during film formation, and the shutter 23 is closed during non-film formation to prevent contamination of the film formation surface. . The opening and closing control of the shutter 23 is performed by the control device 15. At the time of film formation, the substrate stage 14 rotates the substrate S about the center axis J of the opening 4 as a center of rotation, or rotates the substrate S while revolving around the axis J. By such an operation of the substrate stage 14, the sputtered particles 22 emitted from each of the targets 11A and 11B are uniformly deposited on the substrate S. The rotation speed of the substrate S is set at about 20 (rpm) to about 1000 (rpm).
[0014]
FIG. 2 is a view showing the arrangement of the targets 11A and 11B, and is a view when the targets 11A and 11B are viewed from the substrate stage 14 side. Two rectangular targets 11A and 11B are provided respectively, and are alternately arranged at rotationally symmetric positions about the axis J. These targets 11A and 11B are arranged so that the target surface is substantially along a virtual conical surface centered on the axis J as shown in FIG.
[0015]
Basically, the number of the targets 11A and 11B only needs to be one. However, by increasing the number of the targets 11A and 11B such as two, three, four,. The efficiency of the film can be further improved. That is, by surrounding the axis J without gaps by the targets 11A and 11B, it is possible to effectively use the plasma extracted along the magnetic lines 13 of FIG. Note that the angle between the axis J and the target surface in FIG. 1 is suitably about 30 (deg) to 80 (deg).
[0016]
FIG. 3 is a diagram showing the target portion in detail. The targets 11A and 11B have exactly the same configuration except for the target members 111A and 111B. For the target members 111A and 111B, a material corresponding to the layers a and b to be formed is used, and a bias voltage applied to each is set to an optimum voltage according to the target members 111A and 111B. Each of the targets 11A and 11B is provided with a shutter 20 that can be opened and closed. When the shutter 20 is closed, the target surfaces of the target members 111A and 111B are covered, and when the shutter 20 is opened, the target surfaces are exposed to plasma. The opening and closing control of the shutter 20 is performed by the control device 15 of FIG.
[0017]
The target members 111A and 111B are bonded to a metal backing plate 112, and a bias voltage from bias power supplies 12A and 12B is applied to each backing plate 112. A cooling jacket 113 is provided on the back side of the backing plate 112, and the target members 111A and 111B are cooled by cooling water flowing in the cooling jacket 113. Grounded shields 114 are provided on the side and back sides of the target members 111A and 111B, the backing plate 112, and the cooling jacket 113.
[0018]
FIG. 3 shows the shutter open / close state and the bias voltage on / off state when the target 11A forms the a layer. The plasma extracted into the film forming chamber 3 contains argon ions 21. The argon ions 21 are accelerated by a negative bias voltage applied to the targets 11A and impact the surface of the target member 111A. . Due to this impact, the atoms and the lump of atoms are elastically scattered from the target member 111A and are deposited on the substrate S. As a result, a thin film forming the a layer is formed on the substrate S.
[0019]
FIG. 4 is a diagram illustrating an example of a film forming procedure when the thin film layers a and b are alternately stacked on the substrate S. In this case, first, the film formation processing of the a layer (S101, S102) is performed, and then the film formation processing of the b layer (S103, S104) is performed. Then, when the film formation of the b layer is completed, a thin film layer is formed again in the order of the a layer and the b layer. By repeating such film formation N times, a multilayer film in which a layers and b layers are alternately formed N layers each is formed on the substrate S. Hereinafter, the film forming operation will be described with reference to FIGS.
[0020]
In step S100, the substrate S is loaded into the film forming chamber 3 and mounted on the substrate stage 14. At this point, the bias voltages to the targets 11A and 11B are turned off, and the shutters 20 and 23 are both closed. Next, in step S101, pre-sputtering of the target 11A is performed to remove contaminants adhering to the target surface of the target 11A. That is, the shutter 20 of only the target 11A is opened, the bias voltage of the target 11A is turned on, and the target surface is sputtered with argon ions 21. This sputtering removes contaminants adhering to the target surface.
[0021]
When the pre-sputtering in step S101 is completed, the process proceeds to step S102, in which the shutter 23 of the substrate S is opened, and the layer a is formed using the target 11A. During the formation of the a-layer, the shutter 20 of the target 11B is closed, and the bias voltage is also turned off. By closing the shutter 20, contamination of the target surface of the target 11B by the sputtered particles 22 from the target material 111A is reduced. After a lapse of a predetermined time required for forming the a-layer, the shutter 23 is closed and the bias voltage of the target 11A is turned off. In step S103, the shutter 20 of the target 11B is opened, the bias voltage of the target 11B is turned on, and the target 11B is pre-sputtered.
[0022]
Thereafter, in step S103, the shutter 23 is opened, and the b layer is formed using the target 11B. After a lapse of a predetermined time required for forming the b-layer, the shutter 23 is closed and the bias voltage of the target 11B is turned off. In step S105, it is determined whether an N layer has been formed for each of the a layer and the b layer. If it is determined in step S105 that the N-layer film formation has not been completed, the process proceeds to step S101. If it is determined that the N-layer film formation has been completed, the process proceeds to step S106, and the substrate S is carried out of the film formation chamber 3. .
[0023]
(Concrete example)
As an example of a dielectric multilayer filter used for an optical filter, there is a filter in which Ta ₂ O ₅ (a layer) and SiO ₂ (b layer) are alternately laminated. In this case, Ta is the target material 111A is, the target material 111B Si are used respectively, each oxide film by a reactive sputtering where a reactive gas _{O 2} is introduced into the film forming chamber 3 _{(Ta 2 O} 5, SiO ₂ ). In the case of ECR sputtering, active plasma is also formed in the vicinity of the substrate, so that the film forming reaction is promoted and the film forming efficiency is improved.
[0024]
[Modification]
When forming a multilayer film of an alloy thin film. For example, consider a multilayer film composed of an a layer and a b layer, wherein the a layer is an alloy thin film of the substance m1 and the substance m2, and the b layer is an alloy thin film of the substance m3 and the substance m4. FIG. 5 is a view of the target arrangement in this case as viewed from the substrate side. The target 11A uses a substance m1 as a target material, the target 11B uses a substance m2 as a target material, the target 11C uses a substance m3 as a target material, and the target 11D uses a substance m4 as a target material.
[0025]
When the a layer is formed, a bias voltage is applied only to the targets 11A and 11B, and the bias voltage is turned off and the shutter 20 is closed for the targets 11C and 11D that are not used. On the other hand, when the layer b is formed, a bias voltage is applied only to the targets 11C and 11D, and the bias voltage is turned off for the other targets 11A and 11B and the shutter 20 is closed.
[0026]
As described above, in the present embodiment, a plurality of targets 11A and 11B are provided in the film forming chamber 3, and the on / off of the applied voltage by the bias power supplies 12A and 12B is switched, so that the thin film to be formed on the substrate S is formed. Type can be selected arbitrarily. As a result, the a layer and the b layer can be alternately formed in the same film forming chamber 3, and waste caused by the transfer operation between the a layer film forming chamber and the b layer film forming chamber in the conventional in-line sputtering apparatus. Time can be eliminated. Further, since only one film forming chamber 3 is required, it is possible to reduce the cost of the apparatus and the area occupied by the apparatus. By closing the shutter 20 of the target not used for film formation, contamination of the target surface can be reduced, a thin film with less contaminants can be formed, and the pre-sputtering time can be reduced. be able to.
[0027]
In the above-described embodiment, the targets 11A, 11B, 11C, and 11D are arranged in a conical shape with respect to the axis J, but may be arranged in a cylindrical shape. Further, the present invention is not limited to the above-described embodiment at all, as long as the features of the present invention are not impaired.
[0028]
【The invention's effect】
As described above, according to the ECR sputtering apparatus of the present invention, an arbitrary one of a plurality of types of thin films is selected and formed on a substrate by controlling the on / off of a bias voltage applied to a target by a control device. be able to. Further, by laminating these thin films in order, a multilayer film can be formed in a shorter time.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an ECR sputtering apparatus according to the present invention.
FIG. 2 is a diagram showing an arrangement of targets 11a and 11B.
FIG. 3 is a diagram showing a target portion in detail.
FIG. 4 is a diagram showing an example of a film forming procedure when thin film layers a and b are alternately stacked.
FIG. 5 is a diagram showing an arrangement of targets in a modified example.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 ECR sputtering apparatus 2 Plasma generation chamber 3 Film formation chamber 4 Plasma extraction opening 5 Air-core coil 6 Microwave source 8 Microwave introduction windows 11A, 11B, 11C, 11D Targets 12A, 12B DC bias power supply 14 Substrate stage 15 Control device 20, 23 Shutter S Substrate

Claims (3)

An ECR sputtering apparatus that generates plasma by electron cyclotron resonance and sputters a target with ions in the generated plasma to form a plurality of types of thin films on a substrate,
A plurality of targets provided according to the plurality of types of thin films,
A bias power supply for individually applying a bias voltage to the plurality of targets;
And a control device for controlling the bias power so that a bias voltage is applied only to a target provided for the thin film when the thin film is formed, and the control device applies the bias voltage to the target. An ECR sputtering apparatus wherein a bias voltage is controlled to form a thin film arbitrarily selected from the plurality of types of thin films. The ECR sputtering apparatus according to claim 1,
An ECR sputtering apparatus comprising: a shielding means for covering a sputtering surface of a target to which the bias voltage is not applied and for preventing incidence of sputter particles. A multilayer film forming method for forming a multilayer film on a substrate by using the ECR sputtering apparatus according to claim 1 or 2,
A method of forming a multilayer film, wherein a via voltage is sequentially applied to the plurality of targets to form respective layers constituting the multilayer film in order.

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