TWI839548B - Sputtering device - Google Patents

Abstract

The subject of the present invention is to provide a sputtering device that can effectively suppress the disappearance of the anode for a long time when a dielectric film is formed by sputtering a target material. The solution of the present invention is that the sputtering device (SM) is equipped with: a vacuum chamber (1), a target material (2) and a sputtering power source (Ps), which inputs a specific power to the target material, forms a plasma atmosphere in the vacuum chamber by inputting power to the target material, and sputters the target material, and forms a dielectric film on the surface of the substrate (Sw) in the vacuum chamber, which will function as an anode during sputtering. The annular member (3) is arranged to surround the target material. The annular member is configured so that its top surface (30) is located below the sputtered surface (2a) of the target material. An anti-adhesion plate (6) is provided around the target material and partially covers the floating potential of the top surface of the annular member. Furthermore, the annular member has a positive potential maintaining means for maintaining the annular member at a positive potential.

Description

Sputtering device

The present invention relates to a sputtering device, which comprises: a vacuum chamber, a target material, and a sputtering power source, which inputs a specific power to the target material, forms a plasma atmosphere in the vacuum chamber by inputting power to the target material, and sputters the target material to form a dielectric film on the surface of a substrate in the vacuum chamber.

In the process of manufacturing semiconductor devices, 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. In the formation of such a dielectric film, a sputtering device may be used (for example, refer to Patent Document 1). In such a sputtering device, for example, for the sake of discharge stability, an annular member (ground shield) that functions as an anode is generally provided to surround the target material. Here, if the target material is sputtered, the sputtering particles scattered from the target material or the reaction products thereof with the reaction gas will not only adhere to and accumulate on the surface of the substrate, but also adhere to and accumulate on the surface of the annular member facing the plasma atmosphere. However, if the surface of the ring-shaped member is covered with a dielectric film (insulating film), the so-called anode disappearance will occur, making the discharge unstable, and thus, it will be impossible to form a good dielectric film.

In the above-mentioned conventional structure, grooves are formed on the surface of the annular member to suppress the adhesion and accumulation of plating particles or reaction products on the inner surface (especially the bottom surface) of the groove as much as possible. However, when the surface of the annular member is covered with a dielectric film (insulating film), the area that functions as an anode is small, and as a result, there is a problem that the anode cannot be effectively prevented from disappearing for a long time (for example, until the target life limit). [Prior technical literature] [Patent literature]

[Patent Document 1] Japanese Patent Application Publication No. 2001-164360

[The problem the invention is trying to solve]

In view of the above points, the present invention aims to provide a sputtering device that can effectively suppress the disappearance of the anode for a long time when forming a dielectric film by sputtering a target material. [Means for solving the problem]

In order to solve the above problems, the sputtering device of the present invention comprises: a vacuum chamber, a target material, and a sputtering power source, which inputs a specific power to the target material, forms a plasma atmosphere in the vacuum chamber by inputting power to the target material, and sputters the target material to form a dielectric film on the surface of the substrate in the vacuum chamber, and is characterized in that a ring-shaped member that functions as an anode during the sputtering of the target material surrounds the target material. The annular member is arranged in a surrounding manner, with the sputtered surface side of the target material along the thickness direction of the target material as the upper side, and the annular member is configured in a manner so that its upper side is located below the sputtered surface of the target material, and an anti-adhesion plate of a floating potential is provided which is arranged around the target material and partially covers the upper side of the annular member, and further has a positive potential maintaining means for maintaining the annular member at a positive potential.

According to the present invention, when sputtering is performed on a target material, sputtering particles or reaction products thereof with a reactive gas will scatter toward an annular component facing a plasma atmosphere. However, since the top surface of the annular component is partially covered by the anti-adhesion plate, the sputtering particles or reaction products can be suppressed as much as possible from adhering to and accumulating on the top surface of the annular component covered by the anti-adhesion plate. In addition, by means of a positive potential holding means, the annular member (and further, the upper portion of the annular member covered by the anti-adhesion plate without the adhesion or accumulation of sputtered particles or reaction products) is held at a positive potential. Therefore, even in the case where film formation is performed by sputtering in a vacuum chamber under the general conditions of forming a dielectric film on the annular member, the anode can be effectively prevented from disappearing for a long time (for example, until the target life limit). At this time, by setting the anti-adhesion plate to a floating potential, the selectivity of the anode can also be improved. In addition, as the anti-adhesion plate, a structure having an annular shielding plate portion can be adopted. At this time, in this setting state, an annular area on the upper surface of the annular member facing the plasma atmosphere is exposed.

In the present invention, it is more preferable that the sputtering power source is constituted by a pulsed DC power source, the negative output of which is connected to the target material, and the positive output of which is connected to the annular member, so that the sputtering power source also serves as a positive potential holding means. If so, the number of parts can be reduced and the cost can be reduced.

In the present invention, it is preferable to further provide a cooling means for cooling the annular member in order to prevent thermal deformation of the annular member. In addition, a gas introduction means capable of introducing the sputtering gas may be provided at a portion other than the upper surface of the annular member, so that the sputtering gas can be uniformly supplied to the vicinity of the target. In addition, the provision of the gas introduction means includes providing a gas passage through the inside of the annular member.

Hereinafter, with reference to the attached drawings, the sputtering device of the embodiment of the present invention will be described by taking as an example the case where the substrate is a silicon wafer having a circular outline (hereinafter referred to as "substrate Sw"), the target material is made of aluminum, and an aluminum oxide film (hereinafter referred to as "aluminum oxide film") is formed on the surface of the substrate Sw by a reactive sputtering method with oxygen gas introduced therein. Hereinafter, the terms indicating directions such as "up" and "down" are described based on the installation posture of the sputtering device SM shown in FIG. 1.

Referring to FIG. 1 , SM is a sputtering device of this embodiment, and the sputtering device SM has a vacuum chamber 1. The vacuum chamber 1 is connected to an exhaust pipe 11 that communicates with a vacuum pump unit Pu composed of a turbomolecular pump or a rotary pump, and is configured to be able to evacuate the vacuum chamber 1 to a specific pressure (e.g., 1×10 ^-5 Pa).

A target 2 is provided in the vacuum chamber 1. A back plate 21 made of, for example, Cu is bonded to the bottom of the target 2 via an adhesive material (not shown), and is arranged on the bottom wall of the vacuum chamber 1 via an insulator _101. In addition, a negative output from a pulsed DC power source as a sputtering power source Ps is connected to the target 2, so that a specific power having a negative potential at a specific frequency can be input to the target 2. As the pulsed DC power source Ps, a well-known structure can be used, and therefore, further detailed description is omitted.

An annular member 3 is arranged in the vacuum chamber 1 so as to surround the target 2. The annular member 3 is composed of an annular anode plate portion 31 and a cylindrical leg portion 32, and is arranged at the lower wall of the vacuum chamber 1 via the leg portion 32. The anode plate portion 31 is arranged parallel to the sputtered surface 2a of the target 2; and the leg portion 32 is provided integrally with the lower surface of the anode plate portion 31. In this case, an insulator Io ₂ is provided between the leg portion 32 and the vacuum chamber 1, so that the annular member 3 and the vacuum chamber 1 are electrically insulated. The height h1 of the foot portion 32 from the lower wall of the vacuum chamber 1 is controlled in size so that the upper surface 30 of the anode plate portion 31 is located below the sputtering surface 2a of the target 2 in consideration of the position of the first anti-adhesion plate 6 described later.

Furthermore, the annular member 3 has an annular cooling block 4, which is provided so as to cover the entire surface thereof and respectively contact the lower surface of the anode plate portion 31 and the inner peripheral surface of the leg portion 32, and is configured so that cooling water can circulate in the passage in the cooling block 4 through a cooling unit (not shown). This cooling block 4 is an implementation form of the cooling means of the present invention. Furthermore, a gas introduction pipe 5 having gas ejection ports 51 formed at specific intervals is attached to the cooling block 4. A gas pipe 53 is connected to the gas source of the sputtering gas and is provided with a flow control valve such as a mass flow controller 52, so that the sputtering gas can be uniformly introduced to the vicinity of the target material 2 at a specific flow rate through the gap between the first anti-adhesion plate 6 and the second anti-adhesion plate 7 described later. These gas introduction pipes 5 and the mass flow controller 52 constitute an embodiment of the gas introduction means of the present invention. The sputtering gas contains argon as a rare gas for discharge and oxygen as a reaction gas. In addition, a passage for circulating cooling water or a passage for sputtering gas may be provided in the foot 32.

The positive output of the pulsed DC power source Ps is further connected to the annular member 3, and a positive potential is applied to the annular member 3 at a specific frequency, so that the positive potential is constantly maintained on the annular member 3. In this embodiment, although the pulsed DC power source Ps is used as a positive potential maintaining means, it is not limited to this, and a positive potential can also be constantly applied to the annular member 3 during sputtering by using another DC power source.

In the vacuum chamber 1, a first anti-adhesion plate 6 is provided to surround the target material 2. The first anti-adhesion plate 6 is composed of a shielding plate portion 61 and a cylindrical leg portion 62, and is arranged at the lower wall of the vacuum chamber 1 through the leg portion 62 extending through the space between the back plate 21 and the annular member 3. The shielding plate portion 61 partially covers the anode plate portion 31 of the annular member 3; and the leg portion 62 is integrally provided under the shielding plate portion 61. In this case, an insulator Io ₃ is provided between the leg portion 62 and the vacuum chamber 1, so that the first anti-adhesion plate 6 is electrically insulated from the vacuum chamber 1 and becomes a floating potential. The height h2 of the foot portion 62 from the lower wall of the vacuum chamber 1 is controlled in size so that the upper surface 6a of the shielding plate portion 61 having a specific plate thickness is located on a substantially coplanar surface with the sputtering surface 2a when not in use, and a specific gap is formed between the lower surface of the shielding plate portion 61 and the upper surface 30 of the anode plate portion 31. This gap is appropriately set so that plasma does not enter. Thus, when a plasma atmosphere is formed in the space in the vacuum chamber 1 between the substrate Sw and the target 2, the annular region 30a facing the plasma atmosphere at the upper surface 30 of the annular member 3 is exposed, and the annular region 30b further inside the region 30a is covered by the shielding plate portion 61 to shield the plasma atmosphere. Around the first anti-adhesion plate 6, a second anti-adhesion plate 7 made of metal, for example, is provided at intervals to prevent film deposition on the inner wall surface of the vacuum chamber 1. The second anti-adhesion plate 7 is composed of an annular flat plate portion 71, a cylindrical leg portion 72, and a cylindrical rising portion 73, and is arranged at the lower wall of the vacuum chamber 1 via the leg portion 72. The leg portion 72 is integrally provided under the flat plate portion 71; the rising portion 73 rises upward from the outer edge of the flat plate portion 71. In this case, although the second anti-adhesion plate 7 is at the same ground potential as the vacuum chamber 1, an insulator may be provided between the foot 72 and the vacuum chamber 1 so that the second anti-adhesion plate 7 is electrically insulated from the vacuum chamber 1 and is at a floating potential.

At the upper part of the vacuum chamber 1, a substrate transporting means 8 capable of transporting the substrate Sw to a position opposite to the target 2 is provided. As the substrate transporting means 8, for example, a well-known structure having a rail member 81, a slide 82, and a support 83 can be used, so detailed description is omitted. The rail member 81 extends in the transport direction of the substrate Sw (left-right direction in FIG. 1); the slide 82 is freely slidably engaged with the rail member 81; and the support 83 is provided on the slide 82 to hold the substrate Sw with its film forming surface facing downward. In addition, although not particularly shown in the figure, the sputtering device SM has a well-known control means such as a microcomputer or a sequencer, and the control means is used to coordinate and control the operation of the vacuum pump unit Pu, the operation of the mass flow controller 52, the operation of the pulse DC power supply Ps, etc. The following is a description of a film forming method for forming an aluminum oxide film on the surface of a substrate Sw by reactive sputtering using the sputtering device SM.

First, after the substrate transport means 8 is used to transport the substrate Sw to a position opposite to the target material 2, the vacuum pump unit Pu is activated to evacuate the vacuum chamber 1 to a specific pressure (e.g., 1×10 ^-5 Pa), and then argon and oxygen are introduced as sputtering gases at a specific flow rate, and power is input to the target material 2 from the pulsed DC power supply Ps to form a plasma atmosphere. If the target material 2 is sputtered by the argon ions in the plasma atmosphere, the sputtering particles scattered from the target material 2 will react with the oxygen, and the reaction products will adhere to and accumulate on the surface of the substrate Sw, forming an aluminum oxide film.

At this time, although the reaction product also scatters toward the annular member 3 facing the plasma atmosphere, since the upper surface 30 of the annular member 3 is partially covered by the shielding plate portion 61 of the first anti-adhesion plate 6, the reaction product adheres to and accumulates in the area 30a (covered by the alumina film) not covered by the shielding plate portion 61, and on the other hand, the reaction product can be suppressed as much as possible from adhering to and accumulating in the area 30b of the annular member 3 covered by the shielding plate portion 61. Therefore, compared with the case where the groove is formed as in the above-mentioned conventional example, the area that functions as an anode can be greatly increased. In addition, by keeping the annular member 3 or even the region 30b of the annular member 3 covered by the first anti-adhesion plate 6 without the adhesion or accumulation of the reaction product at a positive potential, even if the film formation is performed by sputtering in the vacuum chamber 1 under the general conditions that an aluminum oxide film will be formed on the region 30a of the annular member 3, the disappearance of the anode can be effectively prevented for a long time (for example, until the target life limit). At this time, by setting the first anti-adhesion plate 6 to a floating potential, the selectivity of the anode can also be improved. In addition, by setting the second anti-adhesion plate 7 to a floating potential, the selectivity of the anode can be further improved.

Furthermore, in this embodiment, since the sputtering power source Ps is constituted by a pulsed DC power source, its negative output is connected to the target 2, and its positive output is connected to the annular member 3, the sputtering power source Ps is also used as a positive potential holding means, thereby reducing the number of parts and achieving low cost.

Furthermore, during film formation, the ring-shaped member 3 is cooled by the cooling block 4, thereby also preventing thermal deformation of the ring-shaped member 3.

Although the above description is directed to the embodiment of the present invention, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. For example, in the above embodiment, although the case of forming an aluminum oxide film by reactive sputtering using an aluminum target 2 is described as an example, the present invention is not limited to this, and can also be applied when an aluminum oxide film is formed using an aluminum target. In this case, the sputtering particles can be suppressed as much as possible from adhering and accumulating on the area 30b of the annular member 3 covered by the shielding plate portion 61 of the first anti-adhesion plate 6. Furthermore, the dielectric film is not limited to the aluminum oxide film, and the present invention can also be applied when forming other dielectric films such as silicon oxide films.

In the above embodiment, the gas introduction pipe 5 is attached to the inner peripheral surface of the cooling block 4 as an example, but the gas introduction pipe 5 can be provided at any part other than the upper surface 30 of the annular member 3, for example, it can be attached to the outer peripheral surface of the leg 32 of the annular member 3. In this case, the sputtering gas can be introduced into the vicinity of the target 2 through the gap between the first anti-adhesion plate 6 and the second anti-adhesion plate 7.

In the above embodiment, although the so-called upward deposition type sputtering device SM in which the target material 2 is arranged at the lower part of the vacuum chamber 1 is described as an example, the present invention can also be applied to the so-called downward deposition type. In this case, a platform can be arranged at the lower part of the vacuum chamber, and the substrate can be held on the platform.

Ps: Pulsed DC power supply (sputtering power supply, positive potential holding means) SM: Sputtering device Sw: Substrate 1: Vacuum chamber 2: Target 2a: Sputtering surface 3: Ring-shaped member 30: Top of the ring-shaped member 4: Cooling block (cooling means) 5: Gas introduction tube (gas introduction means) 52: Mass flow controller (gas introduction means) 6: First anti-adhesion plate (anti-adhesion plate)

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

1: Vacuum chamber

2: Target material

2a: Splash coating

3: Ring-shaped components

4: Cooling block (cooling means)

5: Gas introduction tube (gas introduction means)

6: The first anti-adhesion plate (anti-adhesion plate)

6a: Above

7: Second anti-adhesion plate

8: Substrate transport method

11: Exhaust pipe

21: Back panel

30: Top of the ring-shaped component

30a: Area

30b: Area

31: Anode plate

32: Feet

51: Gas outlet

52: Mass flow controller (gas introduction method)

53: Gas pipe

61: Shielding plate part

62: Feet

71: Flat plate

72: Feet

73: Standing part

81:Track components

82: Slide

83:Supporter

Ps: Pulse DC power supply (sputtering power supply, positive potential holding means)

Pu: vacuum pump unit

h1,h2: height

Io ₁ ,Io ₂ ,Io ₃ : Insulator

SM: Sputtering device

Sw: Substrate

Claims (3)

A sputtering device comprises: a vacuum chamber, a target material, and a sputtering power source, wherein a specific power is input to the target material, a plasma atmosphere is formed in the vacuum chamber by inputting power to the target material, and the target material is sputtered to form a dielectric film on the surface of a substrate in the vacuum chamber, wherein a ring-shaped member that functions as an anode during sputtering of the target material is arranged to surround the target material, and a dielectric film is formed along the thickness of the target material. The sputtering surface side of the target material in the direction is the upper side, and the annular member is arranged in a manner such that the upper side is located below the sputtering surface of the target material, and an anti-adhesion plate of floating potential is provided around the target material and partially covers the upper side of the annular member, and further has a positive potential holding means for holding the annular member at a positive potential, and further has a cooling means for cooling the annular member. A sputtering device comprises: a vacuum chamber, a target material, and a sputtering power source, wherein a specific power is input to the target material, a plasma atmosphere is formed in the vacuum chamber by inputting power to the target material, and the target material is sputtered to form a dielectric film on the surface of a substrate in the vacuum chamber, wherein a ring-shaped member that functions as an anode during sputtering of the target material is arranged to surround the target material, and the sputtering of the target material along the thickness direction of the target material is controlled by the sputtering power source. The annular member is configured so that its upper surface is located below the sputtering surface of the target material, and an anti-adhesion plate is provided around the target material and partially covers the upper surface of the annular member. Furthermore, a positive potential holding means for holding the annular member at a positive potential is provided. A gas introduction means capable of introducing a sputtering gas is provided at a portion other than the upper surface of the annular member. The sputtering device as described in claim 1 or 2, wherein the sputtering power source is composed of a pulsed DC power source, and its negative output is connected to the target material, and its positive output is connected to the annular component, so that the sputtering power source also serves as a positive potential holding means.

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