JP4111375B2 - Sputtering equipment - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to a sputtering apparatus that is used in manufacturing processes of semiconductors, electronic components, magnetic heads, and the like and forms a thin film on a substrate in a vacuum. More particularly, the present invention relates to a sputtering apparatus for uniformizing the film pressure distribution and film quality distribution of the thin film on the substrate when the thin film is formed on the substrate. The present invention also relates to a method for manufacturing a semiconductor, an electronic component or the like in which a thin film is formed on a substrate by a sputtering method.
[0002]
[Prior art]
The sputtering apparatus includes a substrate holder, a target made of a film material to be formed, and the like, and a vacuum chamber containing them. A gas such as argon used for discharge can be introduced into the vacuum chamber, and a direct current or alternating current voltage can be applied to a target that substantially acts as an electrode at the cathode.
[0003]
At the time of film formation, after the air in the vacuum chamber is exhausted, a discharge gas is introduced so that a predetermined pressure is obtained. By applying a predetermined voltage to the target after introducing the gas, a discharge is generated between the substrate held by the holder and the target, and plasma is generated. Gas molecules and the like ionized in the plasma sputter the target surface, and target constituent elements knocked out by the sputtering adhere to and deposit on the substrate surface to form a thin film.
[0004]
Usually, in the above-described sputtering apparatus, a target having a surface area larger than that of the substrate is used in order to make the film pressure distribution or film quality distribution of the thin film formed on the substrate uniform. Although depending on the distance between the substrate and the target or the pressure at the time of discharge, when trying to obtain uniformity such as a film thickness of a certain level or more, the surface area of the target is about 4 times the surface area of the substrate. It is said that it is necessary to double.
[0005]
[Problems to be solved by the invention]
In recent years, in the manufacturing process of a liquid crystal display, a semiconductor, and the like in which a thin film is formed using a sputtering apparatus, a large-sized substrate has been actively promoted in order to increase production efficiency. However, when a target having a surface area corresponding to the substrate is used, the target itself becomes large and the voltage to be applied to it becomes very high. For this reason, for example, when an abnormal discharge occurs, there is a possibility that a great deal of damage is caused to the device such as cracking of the target or failure of the power source. In addition, the production of a target having uniform characteristics over the entire area may cause the target price to rise, and depending on the material, the production itself may be difficult.
[0006]
In recent years, a multilayer wiring structure is often used in a semiconductor element. In this multilayer wiring structure, an operation is performed in which fine holes are formed in an insulating layer provided between layers in order to connect wirings existing in different layers, and the holes are filled with metal by a sputtering method. At this time, it is preferable that target constituent elements and the like that reach the substrate by sputtering are concentrated on the bottom surface of the micropores. However, since the elements emitted from the target are radiated according to the cosine law, when a large target is used, it adheres and accumulates on the sidewalls of the micropores, making it difficult to reliably fill the micropores. It becomes.
[0007]
The present invention has been devised to solve the above-described problems, and it is possible to form a thin film having a uniform film thickness and film quality distribution by using a target having a small surface area with respect to the substrate. It aims at providing the sputtering device used. It is another object of the present invention to provide a sputtering apparatus that can reliably fill the aforementioned fine holes by using a target having a small area.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a sputtering apparatus according to the present invention has a substrate, a target, and a cathode for holding the target in a vacuum chamber, and the target is sputtered to form the main constituent elements of the target on the substrate surface. A sputtering apparatus for forming a thin film, comprising: an arm that supports a cathode; and a swing shaft that supports the arm and is connected to a drive device and swings the arm about a predetermined axis by the drive device. And having a specific distance between the center of the cathode and a predetermined axis.
[0009]
In the above sputtering apparatus, the cathode is preferably supported by the arm at a predetermined position in the arm, and the arm is preferably supported by the swing shaft at a position different from the predetermined position. In the sputtering apparatus, it is preferable that the cathode is swung by a driving device via a swinging shaft so that the center of the cathode becomes a track passing over the center of the substrate. In the sputtering apparatus, it is preferable that power supply to the cathode, supply of gas, and supply of cooling water are performed via a swing shaft.
[0010]
In the sputtering apparatus, it is preferable that the substrate is rotationally driven about an axis substantially perpendicular to the substrate. Further, it is preferable that the substrate is linearly driven in a predetermined direction parallel to the surface of the substrate or biaxially driven on a plane parallel to the surface of the substrate. In the sputtering apparatus, it is preferable that the movement speed of the cathode swinging motion performed by the driving device via the swing shaft is different between the swing center and the end portion in the swing range. The sputtering apparatus preferably further includes a horn-shaped earth shield projecting forward from the outer peripheral portion of the target, and gas is preferably supplied toward the horn-shaped interior of the earth shield.
[0011]
Furthermore, in order to solve the above-described problems, a semiconductor and electronic component manufacturing method according to the present invention includes a substrate, a target, and a cathode that holds the target in a vacuum chamber, and a discharge gas is introduced in the vicinity of the target. Then, plasma is generated near the target surface by supplying power to the cathode, the target is sputtered by the ion species generated in the plasma, and a thin film is formed on the substrate with the constituent elements of the target released by sputtering as the main components. A method of manufacturing a semiconductor and an electronic component, wherein a step of forming a thin film on a substrate in a state where plasma is generated is performed while the cathode is swung around an axis located at a location different from the center of the cathode. It is characterized by being.
[0012]
In the above method, the locus of the center of the cathode in the swinging motion of the cathode preferably passes over the center of the substrate. In the above method, it is preferable that the moving speed of the cathode is different between the central portion and the end portion in the swinging range in the swinging motion of the cathode. In the above method, the amount of power supplied to the cathode may be different between the central portion and the end portion in the swinging range in the swinging motion of the cathode.
[0013]
【Example】
FIG. 1 is a partial sectional view showing a schematic configuration of the main part of the sputtering apparatus according to the present invention, and the apparatus is cut along a line 2-2 in FIG. 1, and the cut surface in FIG. A schematic configuration is shown in FIG. The sputtering apparatus 1 includes a vacuum chamber 10, a target holding head 40 supported by an arm 20, a target 41 held by the holding head, a substrate holder 60 that holds a substrate 61, a shutter 15, and the like. The vacuum chamber 10 is connected to a vacuum exhaust system (not shown) composed of a turbo molecular pump or the like.
[0014]
The substrate holder 60 is connected to a substrate rotation motor 62 provided outside the vacuum chamber 10 and is rotatable about the axis A. In addition, a water cooling mechanism (not shown) or the like is provided in the inside, and the temperature of the substrate 61 can be controlled. Note that the cylinder for raising and lowering the substrate, the mask covering the outer periphery of the substrate, and the like used when transferring the substrate 61 are not directly related to the present invention, and thus the description thereof is omitted here.
[0015]
The shutter 15 adheres to the surroundings of the sputtered target constituent elements, etc., when discharge is performed but actual film formation is not yet performed, such as when preliminary discharge is performed to remove the oxide film on the surface of the target 41. Used to prevent deposition. For this reason, it can rotate about the axis B, moves to the front surface of the target 41 during discharge, and moves to a place that does not affect the discharge during film formation. Although the drive mechanism is not shown in the drawing, a drive air cylinder or the like is actually arranged outside the vacuum chamber 10 and rotated by these mechanisms.
[0016]
The arm 20 that supports the target holding head 40 is connected to the arm swinging motor 23 outside the vacuum chamber 10 so as to be swingable about the axis C. The target holding head 20 constituting the cathode holds the target 41 so as to serve as the electrode. The arm 20 is oscillated with respect to the substrate 61 held by the substrate holder 60 so that the target 41 moves in a plane opposite to the substrate 61. In this embodiment, as shown in FIG. 2, the center of the target 41 is driven so as to pass over the center of the substrate 61.
[0017]
Next, these configurations will be described in detail with reference to FIG. 3 showing a schematic cross section of the arm 20, the target holding head 40, the target 41, and the like. The oscillating shaft 21 is swingably supported by a bearing portion 12 fixed to the vacuum chamber 10, and is moved from the atmosphere side to the vacuum side by a seal 13 disposed between the vacuum chamber 10 and the bearing portion 12. The swing shaft 21 can be inserted. In order to ensure the sealing action of the seal 13, the seal portion is subjected to so-called intermediate exhaust, in which the portion is exhausted by a vacuum system (not shown) independently of the vacuum chamber 10. .
[0018]
A gear 24 is fixed to the atmospheric end of the swing shaft 21. The gear 24 engages with a drive gear 25 fixed to the output shaft of an arm swing motor 23 that is a drive device, and the motor 23 swings the swing shaft 21 through these gears. Further, a power supply terminal 26 for supplying power to the target (cathode), supplying cooling water, and supplying gas, a cooling water introduction port 27, and a gas introduction port 28 are provided on the atmosphere side end face of the swing shaft 21, respectively. ing.
[0019]
Since the oscillating shaft 21 is set to the ground potential, the power supply terminal 26 and the conductor 32 that electrically connects this to the target are electrically insulated from the oscillating shaft 21 and the like by the insulator 33. Yes. The cooling water introduction port 27 and the gas introduction port 28 are connected to a cooling water passage 34 and a gas line 35 provided inside the swing shaft 21, respectively.
[0020]
The oscillating shaft 21 is connected to and supports one end of the rotation center of the arm 20 at its vacuum side end. The conductor 32, the insulator 33, and the cooling water passage 34 are also provided inside the arm 20, and these communicate with each other from the inside of the swing shaft 21. The gas line 35 is disposed outside the arm 20 for the convenience of manufacturing the apparatus, but may be disposed inside the arm 20. The arm 20 is supported by the swing shaft 21 at one end, and supports the target holding head 40 at the other end.
[0021]
The target holding head 40 includes an insulating part 42 that actually holds the target and a ground potential part 46 disposed around the target. The insulating part 42 includes an insulating plate 43, a backing plate 44, a permanent magnet 45, and a target 41. The target 41 and the backing plate 44 constitute a cathode, and the target 41 functions as a discharge electrode. In this embodiment, the target 41 and the backing plate 44 are formed in a disk shape, and their centers coincide with the cathode center.
[0022]
The insulating plate 43 has a function of electrically insulating the target 41 from the ground potential so that a voltage can be applied to the target 41 via the conductor 32 and the backing plate 44. The target 41 is fixed to a backing plate 44 whose temperature is controlled by cooling water introduced via the cooling water passage 34, and voltage is applied via the conductor 32 and the backing plate 44.
[0023]
In the present embodiment, a magnetron cathode that can be discharged at a low voltage and can easily obtain a large film forming rate is used. The cathode efficiently traps electrons by using a magnetic field by a permanent magnet or the like, and obtains these effects. In this embodiment, the permanent magnet 45 is disposed between the insulating plate 43 and the backing plate 44, and forms a magnetic field that passes through the nonmagnetic backing plate 44 and leaks to the space on the surface of the target 41.
[0024]
The ground potential portion 46 includes a holding head outer peripheral portion 47 and an earth shield 48. The holding head outer peripheral portion 47 surrounds the outer periphery of the insulating plate 43 or the permanent magnet 45 and fixes and holds it in a predetermined position. The earth shield 48 is disposed so as to cover the outer periphery of the backing plate 44 and the target 41 with a slight gap therebetween, and covers the space in front of the target 41 in a horn shape to prevent excess discharge around these. Cut. In this embodiment, the gas line 35 communicates with the gas line opening 49 formed in the earth shield 48 via the holding head outer peripheral portion 47. The gas used at the time of discharge is introduced through the gas line 35 into the horn-shaped space formed by the shield through the opening 49.
[0025]
With the above configuration, in this sputtering apparatus, the target 41 can be swung in a predetermined plane centered on the axis C while maintaining discharge on the surface of the target 41. Note that the center of the target 41 (which coincides with the center of the cathode in this embodiment) at the time of swinging draws a trajectory passing over the center of the substrate. Thereby, it is possible to form a thin film having a uniform film thickness or the like in a region larger than the surface area of the target.
[0026]
In the present invention, the earth shield 48 can limit the radiation according to the cosine law of the target constituent element or the like. Therefore, it is possible to efficiently deposit the emitted element or the like on the bottom surface of the fine hole opening in the direction perpendicular to the target 41. Further, even when the target 41 is swung to form a thin film on a larger substrate, this effect can be obtained in the same manner.
[0027]
Next, a process of forming a thin film on a specific substrate and manufacturing a semiconductor or an electronic component in the apparatus will be briefly described. First, a specific substrate 61 is placed on the substrate holder 60 and fixed. At that time, the inside of the vacuum chamber 10 may be already exhausted or may be exhausted after placing the substrate. After evacuating the inside of the vacuum chamber 10 to a predetermined pressure, a gas for discharge such as argon is introduced from the gas line opening 49 through the gas line 35 or the like, and the inside of the vacuum chamber 10 is set to a predetermined discharge pressure. In this state, the shutter 15 is positioned in front of the target 41. However, the arrangement of the shutter 15 may be a central portion of the vacuum chamber 10 directly above the substrate 61, or a vacuum separated from the upper portion of the substrate. The corner of the tank 10 may be used.
[0028]
Here, a predetermined voltage is applied to the target 41 via the conductor 32 or the like to generate a discharge, thereby generating plasma. After the oxide on the surface of the target 41 is sputtered and a sufficient time has passed for the discharge state to stabilize, the shutter 15 is retracted from the front of the target 41. At the same time, the swing of the center of the target 41 about the axis C is started, and film formation on the substrate 61 is started. At that time, by rotating the substrate holder 60 and the substrate 61 by the substrate rotating motor 62, it is possible to form a thin film having a uniform film thickness on a larger substrate.
[0029]
Generally, the distribution of film thickness obtained from a single circular target shows a profile in which the central part becomes thicker and the film thickness gradually decreases toward the peripheral part. In this embodiment, a magnetron cathode is used. Therefore, it is possible to improve the film thickness distribution obtained from the target 41 alone by making the magnetic field to be formed appropriate, but the profile in which the peripheral part becomes gradually thinner is the same. For this reason, in the band-shaped film formation region obtained by the swinging of the target 41, a profile in which the film thickness increases along the center line is obtained. A thin film having a flat profile can be formed by passing the substrate through the band-shaped film formation region.
[0030]
However, when the substrate is rotated, the moving speed in the circumferential direction increases as the distance from the center of the substrate increases, and the time for positioning in a region where film formation can be performed is shortened. In addition, when the relationship between the rotation speed of the substrate and the swing cycle of the target 41 is satisfied, a pattern or the like may be formed on the substrate. Therefore, in actual film formation, considering the above, it is preferable to change the moving speed of the target 41 in the swing range according to the swing position, for example.
[0031]
For example, when the substrate and the target are arranged as shown in FIG. 2, the moving speed of the target at the center of the swinging range can be increased and the moving speed at the end of the swinging range can be decreased. preferable. Note that the same effect can be obtained by changing the voltage applied to the target instead of changing the rocking speed or the like. Specifically, the applied voltage may be reduced and the film formation rate may be reduced as the distance from the center of the substrate approaches.
[0032]
In addition, the present invention is also considered suitable for a so-called reactive sputtering method used when forming a thin film such as an oxide or a nitride. In this case, the film formed on the substrate is a film containing a target constituent element as a main component. When film formation is performed by moving the target, the supply state of the reactive gas such as oxygen and nitrogen around the target changes according to the change in the target position, and as a result, the oxygen concentration, nitrogen concentration, etc. in the film are formed. There is a risk of changing depending on the film position. However, in the present invention, a constant amount of fresh reactive gas is stably supplied from the gas line opening 49 provided in the earth shield 48. Therefore, a film having a constant oxygen concentration, nitrogen concentration, etc. can be formed at any swing position of the target 41.
[0033]
In the present embodiment, the target 41 and the like are positioned above the substrate 61 and the like. However, the present invention is not limited to this, and the upper and lower arrangements thereof may be interchanged. It is good also as a form arranged in parallel with the perpendicular direction. Moreover, although the apparatus in which the single target 41 is arrange | positioned in the vacuum chamber 10 is shown, it is good also as a structure by which a some target and several arms etc. which support these are arrange | positioned, for example. At that time, a plurality of targets made of the same constituent material may be arranged as targets, and the operating rate of the apparatus may be increased by sequentially changing the targets to be used according to the degree of consumption of the targets. Further, it may be made of different constituent materials, and a film stack may be formed by sequentially performing film formation using these targets.
[0034]
In this embodiment, a circular target is used, but various shapes such as an ellipse can be used. Further, in the present embodiment, the target holding head 40 may hold a so-called counter target such that a target is arranged separately from the target 41 at a portion where the earth shield 48 is arranged. That is, the present invention can use all the cathodes that are currently known as long as the target holding head 40 can hold the target. In that case, the cathode center and the axis of the swing shaft need only be spaced apart.
[0035]
The applied voltage can be applied in various forms such as direct current, alternating current such as low frequency and high frequency. In that case, it is preferable to appropriately change the shape of the conductor 32 in accordance with the form to be used. The gas introduction position is not limited to the present embodiment, and for example, a gas introduction system separate from the arm 20 may be further provided. Further, a plurality of types of gases may be introduced separately, and may be introduced from different positions, such as a position near the target surface of the earth shield 48 and a position farthest from the target surface.
[0036]
In the present embodiment, the substrate holder 60 is rotatable about the axis A, but the present invention is not limited to this. For example, various movements such as a linear movement in a predetermined direction and a two-dimensional plane operation such as an XY plane can be performed. Further, a plurality of cathodes may be swung by a plurality of arms, and the substrate may be opposed to these cathodes and pass through the front thereof.
[0037]
In this embodiment, the arm is supported by the swing shaft at one end, and the target holding head is supported at the other end. However, the support position is not limited to the end of the arm. Specifically, any configuration is possible as long as the center of rotation of the arm, which is the center of the swing shaft, does not coincide with the center of the cathode and has a specific distance. The support position of the cathode in the arm may be a position different from a predetermined position where the arm is supported by the swing shaft. Further, in this embodiment, the swing shaft has a gear that engages with the drive gear of the swing motor at the atmospheric end and supports the arm at the vacuum end. The support position is not limited to the end.
[0038]
【The invention's effect】
According to the present invention, a thin film having a uniform film thickness and film quality distribution can be formed by swinging a target having a small surface area with respect to the substrate in parallel with the film formation surface on the substrate. It becomes possible. Further, by using a target having a small area and efficiently limiting the direction of element emission from the target, it is possible to reliably fill the fine holes.
[0039]
In the present invention, the application of the voltage required when the target is used as a cathode, the supply of cooling water, the introduction of a gas for discharge, and the so-called intermediate vacuum exhaust applied to each seal part are all shaken. It is done through the dynamic axis. Therefore, these structures are not exposed as a movable part in the vacuum vessel, and voltage can be applied with a simple structure. For this reason, the environment in the vacuum chamber can be kept clean and stable.
[0040]
Further, by using a small-diameter target, film formation can be performed even with a small input voltage, and power saving can be achieved. Further, since the input voltage is small, it is possible to suppress the occurrence of abnormal discharge itself, and even if it occurs, the damage given to the device itself is suppressed to a smaller extent than in the case of the conventional device.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration in a cross section of a sputtering apparatus according to the present invention.
FIG. 2 is a diagram showing a state of the apparatus shown in FIG. 1 as viewed from below in the cross section at 2-2.
FIG. 3 is a view showing a schematic configuration in a section of a swingable electrode in a sputtering apparatus according to the present invention.
[Explanation of symbols]
1: Sputtering apparatus 10: Vacuum chamber 12: Bearing part 13: Seal 15: Shutter 20: Arm 21: Oscillating shaft 22: Gear 23: Arm oscillating motor 24: Gear 26: Feeding terminal 27: Cooling water introduction port 28: Gas introduction port 32: Conductor 33: Insulator 34: Cooling water passage 35: Gas line 40: Target holding head 41: Target 42: Insulating part 43: Insulating plate 44: Backing plate 45: Permanent magnet 46: Ground potential part 47 : Holding head outer periphery 48: Earth shield 49: Gas line opening 60: Substrate holder 61: Substrate 62: Substrate rotating motor

Claims (12)

A sputtering apparatus for disposing a substrate, a target, and a cathode for holding the target in a vacuum chamber, and forming a thin film mainly comprising constituent elements of the target on the substrate surface by sputtering the target,
An arm for supporting the cathode;
An oscillating shaft that supports the arm and is connected to a driving device and oscillates the arm around a predetermined axis by the driving device ;
A horn-shaped earth shield projecting forward from the outer periphery of the target ,
A specific distance is provided between the center of the cathode and the predetermined axis ;
A sputtering apparatus characterized in that gas is supplied toward the horn-shaped internal space of the earth shield .   The apparatus according to claim 1, wherein the cathode is supported by the arm at a predetermined position in the arm, and the arm is supported by the swing shaft at a position different from the predetermined position.   2. The apparatus according to claim 1, wherein the cathode is swung by the driving device via the rocking shaft so that the center of the cathode becomes a trajectory passing over the center of the substrate.   The apparatus according to claim 1, wherein power supply, gas supply, and cooling water supply to the cathode are performed through the swing shaft.   2. The device according to claim 1, wherein the cathode swinging motion performed by the driving device via the swinging shaft is different in moving speed between the swinging center and its end portion in the swinging range.   The apparatus according to claim 1, wherein the substrate is driven to rotate about an axis substantially perpendicular to the substrate. The substrate A device according to any one of claims 1 to 6, characterized in that it is linear driven to the surface parallel to the predetermined direction of the substrate. The substrate A device according to any one of claims 1 to 6, characterized in that it is biaxially driven on a plane parallel to the surface of the substrate. A substrate, a target, and a cathode for holding the target are disposed in a vacuum chamber, a discharge gas is introduced in the vicinity of the target, and power is supplied to the cathode to generate plasma in the vicinity of the target surface. A method of manufacturing a semiconductor and an electronic component, wherein the target is sputtered by ion species generated therein, and a thin film is formed on the substrate with a constituent element of the target released by the sputtering as a main component,
The gas is introduced into the horn-shaped internal space in the horn-shaped earth shield projecting forward from the outer periphery of the darget,
The step of forming a thin film on the substrate in a state where the plasma is generated maintains the plasma by continuing the introduction of the gas, and is centered on an axis located at a location different from the center of the cathode. A production method characterized by being carried out while the cathode is swung. The manufacturing method according to claim 9 , wherein the locus of the center of the cathode in the swinging motion of the cathode passes over the center of the substrate. The method according to claim 9 , wherein in the oscillating motion of the cathode, the moving speed of the cathode is different between the central portion and the end portion in the oscillating range. The method according to claim 9 , wherein in the oscillating movement of the cathode, a power supply amount to the cathode is different between a central portion and an end portion in the oscillating range.

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