KR20210045340A - Sputtering apparatus - Google Patents

Abstract

Provided is a sputtering apparatus capable of effectively suppressing positive electrode disappearance over a long time in a case where a dielectric film is deposited by sputtering a target. The sputtering apparatus (SM) comprising a vacuum chamber (1) having a target (2) arranged therein and a sputtering power supply (Ps) applying predetermined power to the target, deposits a dielectric film on a surface of a substrate (Sw) in the vacuum chamber by applying power to the target to form a plasma atmosphere in the vacuum chamber and sputtering the target. A ring-shaped member (3) functioning as a positive electrode in sputtering is arranged so as to surround a periphery of the target. The ring-shaped member is arranged such that an upper surface (30) thereof is positioned below a sputtering surface (2a) of the target. A deposition preventing plate (6) with a floating potential is arranged around the target to cover a part of the upper surface of the ring-shaped member. A positive potential holding means is further included to hold a positive potential of the ring-shaped member.

Description

Sputtering device {SPUTTERING APPARATUS}

The present invention includes a vacuum chamber in which a target is placed, and a sputter power supply for inputting a predetermined power to the target, and a plasma atmosphere is formed in the vacuum chamber by supplying power to the target, and then the target is sputtered to exist in the vacuum chamber. It relates to a sputtering apparatus for forming a dielectric film on a surface of a substrate.

In the manufacturing process of a semiconductor device, there is a process of forming a dielectric film such as an aluminum oxide film or a silicon oxide film on the surface of a substrate, and a sputtering device is sometimes used to form such a dielectric film (see, for example, Patent Document 1). In such a sputtering apparatus, for example, a ring-shaped member (earth shield) that functions as an anode is generally provided as surrounding the target due to the problem of discharge stability. Here, when the target is sputtered, sputter particles scattered from the target or reaction products of the reaction gas and the sputter particles are adhered and deposited on the surface of the ring-shaped member facing the plasma atmosphere as well as the substrate surface. And when the surface of the ring-shaped member is covered with a dielectric film (insulating film), so-called anode disappearance occurs and the discharge becomes unstable, so that a dielectric film cannot be formed satisfactorily with this.

In the above example, concave grooves are formed on the surface of the ring-shaped member to prevent sputter particles or reaction products from adhering and depositing on the inner surface of the groove (especially the bottom surface). However, when the surface of the ring-shaped member is covered with a dielectric film (insulating film), the area that functions as an anode is small, so it is not possible to effectively prevent the loss of the anode over a long period of time (for example, until the end of the target life). there is a problem.

Patent Document 1: Japanese Patent Laid-Open No. 2001-164360

In view of the above points, it is an object of the present invention to provide a sputtering device capable of effectively suppressing loss of an anode over a long period of time when a target is sputtered to form a dielectric film.

In order to solve the above problems, a vacuum chamber in which a target is placed, and a sputter power supply for supplying a predetermined power to the target are provided, and a plasma atmosphere is formed in the vacuum chamber by supplying power to the target, and the vacuum chamber is sputtered by the target. In the sputtering apparatus according to the present invention for depositing a dielectric film on the surface of a substrate present in the target, a ring-shaped member that functions as an anode during target sputtering is installed so as to surround the target, and the sputter surface side of the target is upward along the thickness direction of the target. At the same time, the ring-shaped member is disposed so that its upper surface is located below the sputtering surface of the target, and at the same time, an anti-rust plate is installed that partially covers the upper surface of the ring-shaped member and has a floating potential, and is installed around the target. It is characterized by further comprising a positive electric potential holding means for holding at a positive electric potential.

According to the present invention, when the target is sputtered, sputtering particles or reaction products of the reaction gas and the sputtering particles are scattered toward the ring-shaped member facing the plasma atmosphere, but the upper surface of the ring-shaped member is partially covered by the anti-deposition plate, Attachment and deposition of sputter particles and reaction products to the upper surface portion of the ring-shaped member covered with this anti-rust plate is suppressed as much as possible. In addition, the ring-shaped member (the portion of the upper surface of the ring-shaped member covered with an anti-rust plate and where sputter particles or reaction products do not adhere and deposit) is maintained at a positive potential, even if the dielectric film is formed on the ring-shaped member. Even when film formation is carried out by sputtering in a vacuum chamber under the film-forming condition, it is possible to effectively prevent the loss of the anode over a long period of time (for example, until the end of the target life). At this time, the selectivity of the positive electrode can also be improved by making the barrier plate have a floating potential. In addition, a configuration having an annular shielding plate may be employed as the anti-rust plate. In this case, in the installed state, an annular region facing the plasma atmosphere is exposed on the upper surface of the ring-shaped member.

In the present invention, the sputtering power source is composed of a pulsed DC power source, its negative output is connected to the target, and its positive output is connected to the ring-shaped member, so that the sputtering power source also serves as a positive potential holding means. It is desirable to do it. Through this, it is possible to reduce the number of parts and reduce the cost.

In the present invention, in order to prevent thermal deformation of the ring-shaped member, it is preferable to further include a cooling means for cooling the ring-shaped member. Further, it is also possible to adopt a configuration in which a gas introduction means is provided so that sputter gas can be introduced to a portion other than the upper surface of the ring-shaped member, so that the sputter gas can be uniformly supplied to the vicinity of the target. Here, that the gas introduction means is provided includes that the gas passage is drilled inside the ring-shaped member.

1 is a schematic diagram showing a sputtering device according to an embodiment of the present invention.

Below, referring to the drawings, a reactive sputtering method in which oxygen gas is introduced into the surface of the substrate Sw with the substrate as a silicon wafer having a circular outline (hereinafter,'substrate (Sw)') and the target made of aluminum. As an example, a case where an aluminum oxide film (hereinafter, "alumina film") is formed is taken as an example, and a sputtering apparatus according to an embodiment of the present invention will be described. In the following, terms indicating directions such as “up” and “down” will be described based on the installation state of the sputtering device SM shown in FIG. 1.

Referring to FIG. 1, SM is a sputtering device according to the present embodiment, and the sputtering device SM has a vacuum chamber 1. The vacuum chamber 1 is connected to an exhaust pipe 11 through a vacuum pump unit Pu composed of a turbomolecular pump or a rotary pump, so that the inside of the vacuum chamber 1 is at a predetermined pressure (for example, 1 × 10 ^-5). Pa) can be evacuated.

A target 2 is installed in the vacuum chamber 1. A backing plate 21 made of, for example, copper is bonded to the lower surface of the target 2 through a bonding material (not shown), and is disposed on the lower wall of the vacuum chamber 1 through an _{insulator Io 1.} A negative output from a pulsed DC power source is also connected to the target 2 as a sputter power source Ps, so that a predetermined power having a negative potential can be applied to the target 2 at a predetermined frequency. Since a known pulsed DC power supply Ps can be used, further description will be omitted.

In the vacuum chamber 1, a ring-shaped member 3 is disposed to surround the target 2. The ring-shaped member 3 includes an annular anode plate portion 31 arranged in parallel with the sputtering surface 2a of the target 2, and a cylindrical leg portion 32 integrally provided on the lower surface of the anode plate portion 31. ), and is disposed on the lower wall of the vacuum chamber 1 through the leg portion 32. _{In this case, an insulator Io 2} is provided between the leg portion 32 and the vacuum chamber 1, so that the ring-shaped member 3 is electrically insulated from the vacuum chamber 1. The height h1 from the lower wall of the vacuum chamber 1 to the leg part 32 is the upper surface 30 of the positive electrode plate part 31 in its installed state in consideration of the position of the first anti-rust plate 6 to be described later. It is determined to be located below the sputtering surface 2a of the target 2.

In addition, the ring-shaped member 3 is provided with an annular cooling block 4 provided on the lower surface of the positive electrode plate 31 and the inner circumferential surface of the leg portion 32 so as to abut each over the entire surface thereof. The cooling water can be circulated through the passage in the cooling block 4 by the cooler. This cooling block 4 constitutes an embodiment of the cooling means of the present invention. The cooling block 4 is also provided with a gas introduction pipe 5 in which a gas outlet 51 is formed at predetermined intervals, and the gas introduction pipe 5 includes a mass flow controller 52 connected to a gas source of sputtered gas. The gas pipe 53 in which the flow control valve of is inserted is connected, and the sputter gas is supplied at a predetermined flow rate in the vicinity of the target 2 through the gap between the first and second anti-rust plates 6 and 7 to be described later It can be introduced uniformly. Such a gas introduction pipe 5 and a mass flow controller 52 constitute an embodiment of the gas introduction means of the present invention. The sputter gas contains argon gas as an inert gas for discharge and oxygen gas as a reactive gas. In addition, a passage through which cooling water can be circulated or a passage of sputter gas may be drilled through the leg portion 32.

The ring-shaped member 3 is further connected with a positive output of a pulsed DC power supply Ps so that a positive potential is applied at a predetermined frequency, so that the ring-shaped member 3 always has a positive potential. In the present embodiment, the pulsed DC power supply Ps also serves as a positive potential holding means, but is not limited thereto, and a positive potential may always be applied to the ring-shaped member 3 during sputtering by a separate DC power supply.

In the vacuum chamber 1, a first anti-rust plate 6 is provided to surround the target 2. The first shielding plate 6 includes a shielding plate portion 61 partially covering the positive electrode plate portion 31 of the ring-shaped member 3, and a cylindrical leg portion 62 integrally provided on the lower surface of the shielding plate portion 61 It is composed of, and is disposed on the lower wall in the vacuum chamber 1 through the leg portion 62 extending through the space between the backing plate 21 and the ring-shaped member 3. _{In this case, an insulator Io 3} is provided between the leg portion 62 and the vacuum chamber 1, so that the first anti-rust plate 6 is electrically insulated from the vacuum chamber 1 to become a floating potential. The height h2 from the lower wall of the vacuum chamber 1 to the leg 62 is approximately the same as the sputtering surface 2a when the upper surface 6a of the shielding plate 61 having a predetermined thickness is not in use. It is determined to be positioned on a plane and to form a predetermined gap between the lower surface of the shielding plate part 61 and the upper surface 30 of the positive electrode plate part 31. This gap is appropriately set so that the plasma does not return. Through this, when a plasma atmosphere is formed in the space in the vacuum chamber 1 located between the substrate Sw and the target 2, a ring-shaped area facing the plasma atmosphere on the upper surface 30 of the ring-shaped member 3 (30a) is exposed, and the annular region 30b located inside the region 30a is covered by the shielding plate portion 61 and shielded from the plasma atmosphere. A second barrier plate 7 made of, for example, metal is provided around the first barrier plate 6 at intervals to prevent a film from being formed on the inner wall surface of the vacuum chamber 1. The second anti-rust plate (7) is an annular flat plate portion (71), a cylindrical leg portion (72) integrally installed on the lower surface of the flat plate portion (71), and rises upward from the outer periphery of the flat plate portion (71). It is composed of a cylindrical standing portion 73 and is disposed on the lower wall of the vacuum chamber 1 through the leg portion 72. In this case, the second barrier plate 7 has the same ground potential as the vacuum chamber 1, but an insulator is placed between the leg portion 72 and the vacuum chamber 1 so that the second barrier plate 7 becomes the vacuum chamber ( It can be electrically insulated from 1) so that it becomes a floating potential.

A substrate transfer means 8 capable of transferring the substrate Sw to a position opposite to the target 2 is provided in the upper part of the vacuum chamber 1. As the substrate conveyance means 8, for example, a rail member 81 extending in the conveyance direction of the substrate Sw (in the left and right directions in FIG. 1), and a slider coupled to the rail member 81 so as to be slidable. (82), a known one having a holder 83 installed on the slider 82 and holding the substrate Sw with its film-forming surface facing downward can be used, and thus a detailed description thereof will be omitted. In addition, the sputtering device (SM), although not shown separately, has a known control means including a microcomputer, a sequencer, etc., by this control means, the operation of the vacuum pump unit (Pu), the operation of the mass flow controller 52, The operation of the pulsed DC power supply (Ps) can be integrated and controlled. Hereinafter, a film forming method of forming an alumina film on the surface of the substrate Sw by reactive sputtering using the sputtering device SM will be described.

First, the substrate Sw is transferred to a position opposite to the target 2 using the substrate transfer means 8, and then the vacuum pump unit Pu is operated to provide a predetermined pressure (for example, in the vacuum chamber 1). For example, ^{after evacuating to 1 × 10 -5} Pa), argon gas and oxygen gas are introduced as sputter gases at a predetermined flow rate, and power is supplied to the target 2 from a pulsed DC power supply (Ps) to generate plasma. Create an atmosphere. When the target 2 is sputtered by argon ions in a plasma atmosphere, sputter particles scattered from the target 2 react with oxygen gas, and the reaction product adheres and deposits on the surface of the substrate Sw, thereby forming an alumina film.

At this time, the reaction product is also scattered toward the ring-shaped member 3 facing the plasma atmosphere, but the upper surface 30 of the ring-shaped member 3 is partially formed by the shielding plate portion 61 of the first barrier plate 6. Because it is covered, the reaction product adheres and deposits in the area 30a not covered by the shielding plate part 61 (covered with an alumina film), but the area 30b of the ring-shaped member 3 covered with the shielding plate part 61 ), the reaction product is not attached or deposited as much as possible. For this reason, compared with the case where the groove is formed as in the previous example, the area functioning as an anode can be greatly expanded. In addition, by holding the region 30b of the ring-shaped member 3, which is covered with the ring-shaped member 3 and further to the first anti-deposition plate 6, where the reaction product is not deposited or deposited, at a positive potential, even if the ring-shaped member 3 ), even when the film is formed by sputtering in the vacuum chamber 1 under the condition that the alumina film is formed in the region 30a, it is possible to effectively prevent the loss of the anode over a long period of time (for example, until the end of the target life). I can. At this time, the selectivity of the anode can also be improved by setting the first anti-rust plate 6 to a floating potential. In addition, positive electrode selectivity can be further improved by making the second anti-rust plate 7 also a floating potential.

In addition, in this embodiment, the sputter power supply Ps is configured as a pulsed DC power supply, its negative output is connected to the target 2 and its positive output is connected to the ring-shaped member 3, respectively, so that the sputter power supply Ps ) Is configured to use both electric potential holding means, so the number of parts can be reduced and cost reduction can be achieved.

Further, by cooling the ring-shaped member 3 by the cooling block 4 during film formation, thermal deformation of the ring-shaped member 3 can also be prevented.

As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, a case where an alumina film is formed through reactive sputtering using an aluminum target 2 has been described as an example, but the present invention is not limited thereto, and even when the alumina film is formed using an alumina target The present invention can be applied. In this case, adhesion and deposition of sputter particles to the region 30b of the ring-shaped member 3 covered with the shielding plate portion 61 of the first shielding plate 6 is suppressed as much as possible. Further, the dielectric film is not limited to an alumina film, and the present invention can also be applied to a case of forming another dielectric film such as a silicon oxide film.

In the above embodiment, the case where the gas introduction pipe 5 is installed on the inner circumferential surface of the cooling block 4 is described as an example, but the gas introduction pipe 5 is located in a portion other than the upper surface 30 of the ring-shaped member 3. It just needs to be installed, for example, it can also be attached to the outer peripheral surface of the leg part 32 of the ring-shaped member 3. Even in this case, sputtering gas can be introduced into the vicinity of the target 2 through the gap between the first and second anti-rust plates 6 and 7.

In the above embodiment, the so-called deposition up sputtering device SM, in which the target 2 is installed below the vacuum chamber 1, was described as an example, but it was also seen in the deposition down sputtering device. The invention can be applied. In this case, a stage may be provided under the vacuum chamber to hold the substrate on the upper surface of the stage.

Ps ... pulsed DC power supply (sputter power supply, positive potential holding means)
SM ... sputtering device
Sw... Substrate
1 ... vacuum chamber
2 ... target
2a ... sputter surface
3 ... ring-shaped member
30 ... top side of ring-shaped member
4 ... cooling block (cooling means)
5 ... gas introduction pipe (gas introduction means)
52 ... mass flow meter (means of gas introduction)
6 ... 1st anti-rust plate

Claims (4)

A vacuum chamber in which the target is placed, and a sputter power supply for applying predetermined power to the target are provided, and a plasma atmosphere is formed in the vacuum chamber by supplying power to the target, and a dielectric on the surface of the substrate existing in the vacuum chamber by sputtering the target In the sputtering apparatus for forming a film,
A ring-shaped member that functions as an anode during target sputtering is installed to surround the target,
When the sputter surface side of the target is placed upward along the thickness direction of the target, the ring-shaped member is arranged so that the top surface is located below the sputter surface of the target, and at the same time, it is installed around the target to partially cover the top surface of the ring-shaped member. A sputtering apparatus, further comprising: a barrier plate having a floating potential, and a positive potential holding means for holding the ring-shaped member at a positive potential. The method of claim 1,
The sputter power source is composed of a pulsed DC power source, and the negative output is connected to the target and the positive output is connected to the ring-shaped member, respectively, so that the sputter power source is configured to both serve as a positive potential holding means. Sputtering device. The method according to claim 1 or 2,
A sputtering apparatus further comprising cooling means for cooling the ring-shaped member. The method according to any one of claims 1 to 3,
A sputtering device, characterized in that a gas introduction means is provided so as to introduce sputter gas to portions other than the upper surface of the ring-shaped member.

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