TWI778032B - Sputtering device - Google Patents

Abstract

[Subject] To provide a sputtering apparatus capable of reducing the number of particles adhering to the surface of a film formation object as much as possible. [Solution] The sputtering apparatus (SM) of the present invention is provided with a vacuum chamber (1) provided with a carbon-made target (2), and a vacuum pump (Vp) for evacuating the vacuum chamber. ), and a stage (4) holding the film-forming object (W) in the vacuum chamber, and after the vacuum chamber is evacuated to a specific pressure by a vacuum pump, the target is sputtered by Here, in order to form a carbon film on the surface of the film-forming object, the sputtering apparatus (SM) is further provided with an adsorbent (7) for cooling the surface to a temperature of 123 K or lower, and the adsorbent is arranged At a specific position within the vacuum chamber where radiation relative to the film-forming object is prevented.

Description

Sputtering device

The present invention relates to a sputtering apparatus, and more specifically, relates to a film-forming carbon film on the surface of a film-forming object.

In the prior art, such a sputtering apparatus is used to form a carbon film as an electrode film of an element such as a nonvolatile memory (for example, refer to Patent Document 1). Such a sputtering apparatus includes a vacuum chamber provided with a carbon-made target, a vacuum pump for evacuating the vacuum chamber, and a film-forming object is arranged opposite to the target in the vacuum chamber and held. platform of things. Moreover, in the vacuum chamber, a shielding plate is provided with a gap from the inner wall of the vacuum chamber and surrounds the film-forming space between the target and the stage. Then, after the vacuum chamber is evacuated to a predetermined pressure by a vacuum pump, a carbon film is formed on the surface of the film formation object by sputtering the target.

Here, when a carbon-made target is sputtered and a film is formed on the surface of the film-forming object, fine particles may adhere to the surface of the film-forming object immediately after the film has been formed. . Since such adhesion of particles can cause a decrease in product yield, it is necessary to suppress the adhesion of particles to the surface of the film formation object as much as possible. because Therefore, the inventors of the present invention have repeatedly studied and found the following knowledge: that is, the carbon particles floating in the vacuum chamber adhere to the film immediately after the film formation as fine particles. on the surface of the object. That is, it is presumed that this is caused by the fact that when sputtering is performed on a target made of carbon, the carbon particles scattered from the target not only adhere to the film-forming object, but also It adheres and accumulates on the surfaces of parts and shielding plates that exist around the target. However, the carbon particles that have been adhered in this way are detached again for some reason, and the carbon particles that have been detached again , the system has not been evacuated, but floated in the vacuum chamber.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2015/122159

The present invention has been made based on the above knowledge, and its subject is to provide a sputtering apparatus capable of reducing the number of particles adhering to the surface of a film-forming object as much as possible.

In order to solve the above-mentioned problems, a sputtering apparatus of the present invention includes a vacuum chamber provided with a carbon-made target, a vacuum pump for evacuating the vacuum chamber, and a film-forming object held in the vacuum chamber. peace of things The sputtering apparatus is used to form a carbon film on the surface of a film-forming object by sputtering the target after evacuating the inside of the vacuum chamber to a specific pressure by means of a vacuum pump. , which is characterized in that: it is further provided with an adsorbent whose surface is cooled to a temperature below 123K, and the adsorbent is arranged at a specific position in the vacuum chamber where radiation to the film-forming object is prevented.

According to the present invention, once the carbon particles floating in the vacuum chamber are adsorbed on the adsorbent, since the surface of the adsorbent is cooled to a temperature below 123K, it is prevented from being detached again. As a result, by reducing the number of carbon particles floating in the vacuum chamber, the number of particles adhering to the surface of the film formation object can be reduced as much as possible. In this case, since the adsorption system is arranged at a specific position in the vacuum chamber where radiation to the film-forming object is prevented, a film-forming process for the film-forming object, such as changing the film quality, does not occur. the problem of adverse effects.

In the present invention, when the target and the platform are arranged to face each other, and are provided in the exhaust space portion that locally protrudes in the direction perpendicular to the extension line connecting the two, The above-mentioned vacuum pump is connected to the exhaust port opened in the exhaust space portion, and the sputtering apparatus is provided with a gap from the inner wall surface of the vacuum chamber and is installed. In the case of a shielding plate surrounded by the film-forming space between the target and the platform, it is preferable to configure the adsorption body to be attached to the outer surface portion of the shielding plate and to be installed with a space therebetween. According to this, the shielding plate itself is cooled by radiation from the adsorbent When the temperature reaches a certain temperature, the shielding plate itself acts as an adsorbent. By using the shielding plate that defines the film-forming space to absorb carbon particles and hold them, the amount of floating carbon particles can be further reduced. favorable.

In this case, it is preferable to set the outer surface portion of the shielding plate in a range facing the exhaust gas inflow port of the exhaust space portion. According to this, by allowing the adsorbent to exist in the exhaust path of the exhaust gas from the film formation space in the vacuum chamber to the exhaust gas portion, the carbon particles can be more easily adsorbed, and for the benefit.

SM: Sputtering device

Vp: vacuum pump

W: substrate (object for film formation)

1: Vacuum chamber

1a: inner wall surface of vacuum chamber 1

11: Exhaust space part

11a: exhaust port

2: Target

4: Platform

5: shielding plate

7: Adsorbent

1 is a schematic cross-sectional view showing a sputtering apparatus according to an embodiment of the present invention.

[ Fig. 2 ] is a cross-sectional view taken along line II-II of Fig. 1 .

[FIG. 3] It is a figure which shows the modification of this embodiment.

Hereinafter, referring to the drawings, a silicon wafer (hereinafter, simply referred to as "substrate W") is the film formation object, and a carbon-made target for sputtering is provided on the upper part of the vacuum chamber, and a An embodiment of the sputtering apparatus according to the present invention will be described by taking a stage provided with the substrate W as an example.

Referring to FIGS. 1 and 2, SM is a sputtering apparatus of a magnetron method according to an embodiment of the present invention. The sputtering apparatus SM is equipped with The vacuum chamber 1 is detachably mounted with the cathode unit Cu at the upper part of the vacuum chamber 1 . The cathode unit Cu is composed of a target 2 made of carbon and a magnet unit 3 arranged above the target 2 .

The target 2 is formed into a circular shape in plan view according to the outline of the substrate W. As shown in FIG. The target 2 is mounted on the baffle plate 21 with its sputtering surface 22 facing downward, and is mounted on the vacuum chamber 1 through the insulator Ib provided on the upper wall of the vacuum chamber 1 at the top. Moreover, the sputtering power supply E having a well-known structure is connected to the target 2, and it is comprised so that the direct current electric power which has a negative electric potential can be input at the time of film formation by sputtering. The magnet unit 3 arranged above the target material 2 generates a magnetic field in the space below the sputtering surface 22 of the target material 2, and ionizes the material below the sputtering surface 22 during sputtering. There is a latching magnetic field or a cusp magnetic field structure that captures electrons and the like and efficiently ionizes the sputtered particles scattered from the target 2 . As the magnet unit itself, since a well-known structure can be used, further detailed description is omitted.

In the center of the bottom of the vacuum chamber 1, a stage 4 is arranged so as to face the target 2 with other insulators Ib interposed therebetween. The platform 4, although not particularly shown and described, is constituted by, for example, a metal base having a cylindrical outline, and a suction plate attached to the upper surface of the base. During the film formation, the substrate W can be adsorbed and held. In addition, about the structure of an electrostatic chuck, since a well-known structure, such as a unipolar type or a bipolar type, can be used, further detailed description is abbreviate|omitted here. In addition, at the base, it is also possible to store a passage or heating for refrigerant circulation. It is configured such that the substrate W can be controlled to a specific temperature during film formation.

In addition, in the vacuum chamber 1, a shielding plate 5 is provided with a gap from the inner wall 1a of the vacuum chamber 1 and surrounds the film-forming space 1b between the target 2 and the stage 4. The shielding plate 5 is provided with a slightly cylindrical upper plate portion 51 that surrounds the target 2 and extends below the vacuum chamber 1 , and a slightly cylindrical portion that surrounds the platform 4 and extends above the vacuum chamber 1 . The lower plate portion 52 is formed such that the lower end of the upper plate portion 51 and the upper end of the lower plate portion 52 overlap each other with a gap in the circumferential direction. In addition, the upper plate portion 51 and the lower plate portion 52 may be formed integrally, or may be configured to be divided into a plurality of parts in the circumferential direction and combined.

Furthermore, the vacuum chamber 1 is provided with gas introduction means 6 for introducing a specific gas. The gas includes not only a rare gas such as argon gas introduced when the plasma is formed in the film formation space 1b, but also a reactive gas such as oxygen gas or nitrogen gas introduced appropriately for film formation. The gas introduction means 6 is provided with a gas ring 61 provided on the outer periphery of the upper plate portion 51, and a gas pipe 62 connected to the gas ring 61 and penetrating the side wall of the vacuum chamber 1. The gas pipe 62 is connected through the The mass flow controller 63 is communicated with a gas source (not shown). In this case, although the detailed illustration is omitted, a gas diffusion part is attached to the gas ring 61, and the sputtering gas system from the gas pipe 62 is diffused by the gas diffusion part, and becomes a In the gas ring 61, the sputtering gas is injected at the same flow rate through the gas injection ports 61a provided at equal intervals in the circumferential direction. Then, the sputtering gas jetted from the gas jetting port 61a is introduced into the film-forming space at a predetermined flow rate from a gas hole (not shown) formed in the upper plate portion 51 In 1b, during film formation, the pressure distribution in the film formation space 1b can be made equal to cover the entirety thereof. In addition, the method for making the pressure distribution in the film-forming space 1b cover the whole and making it the same is not limited to this, Other well-known methods can be suitably used.

In addition, the vacuum chamber 1 is provided with an exhaust space portion 11 that locally protrudes in the direction perpendicular to the center line (extension line) C1 connecting the target 2 and the stage 4 , On the bottom wall surface defining the exhaust space portion 11, an exhaust port 11a is opened. A vacuum pump Vp such as a cryopump or a turbo molecular pump is connected to the exhaust port 11a through an exhaust pipe. During the film formation, a part of the sputtering gas introduced into the film formation space 1b becomes exhaust gas, and is released from the junction of the shielding plate 5 and the gap between the shielding plate 5 and the target 2 or the stage 4. , to flow from the exhaust gas inflow port 11b to the exhaust space portion 11 through the gap between the outer surface of the shielding plate 5 and the inner wall surface 1a of the vacuum chamber 1, and be directed toward the vacuum chamber through the exhaust port 11a. Pu Vp for vacuum exhaust. At this time, a pressure difference of about several Pa is generated between the film formation space 1b and the exhaust space portion 11 .

When a specific thin film is formed on the substrate W, the substrate W is loaded onto the stage 4 by a vacuum transfer robot not shown in the figure, and the substrate W is set on the upper surface of the chuck plate of the stage 4 (in this case , the upper surface of the substrate W becomes the film-forming surface). After that, the vacuum transfer machine is moved in and out, and a specific voltage is applied from the chuck power source to the electrodes for the electrostatic chuck to electrostatically attract the substrate W to the upper surface of the chuck plate. Next, if the vacuum chamber 1 is evacuated to a predetermined pressure (for example, 1×10 ⁻⁵ Pa), the argon gas as the sputtering gas is introduced at a certain flow rate through the gas introduction means 6 , and A specific power is supplied to the target 2 from the sputtering power supply E. Thereby, a plasma is formed in the film-forming space 1b, the target is sputtered by the ions of argon gas in the plasma, and the sputtered particles (carbon particles) from the target 2 are attached. , is deposited on the upper surface of the substrate W, and a carbon film is formed. When sputtering the target 2 to form a carbon film in this way, it was found that the carbon particles floating in the vacuum chamber 1 adhered to the film immediately after the film formation as fine particles. on the surface of the film object. It is presumed that this is caused by the fact that the carbon particles scattered from the target not only adhere to the substrate W, but also adhere and accumulate between the parts existing around the target 2 and the shielding plate 5 . On the surface, however, the carbon particles that have been attached in this way will be detached again for some reason, and the carbon particles that have been detached again are not evacuated, but remain in the vacuum chamber 1. float.

Therefore, in the present embodiment, the adsorbent 7 for cooling the surface to a temperature of 123K or lower is provided at a specific position in the vacuum chamber 1 where radiation to the film-forming object W is prevented. In this case, the adsorption body 7 is installed with a gap between the outer surface portion 52a of the lower plate portion 52 of the shielding plate 5, and the surface is cooled by a cooling mechanism such as a refrigerator (not shown). was cooled to the above temperature. As the cooling mechanism, since a well-known structure can be used, the detailed description is omitted here. The adsorption body 7 is configured so as to be able to move freely in the vertical direction by the elevating mechanism 7a such as a motor, but it may also be erected on the bottom wall surface of the vacuum chamber 1 .

According to the above configuration, if it floats in the vacuum chamber 1 Once the floating carbon particles are adsorbed on the adsorbent 7, since the surface of the adsorbent 7 is cooled to a temperature below 123 K, it is prevented from being detached again. As a result, by reducing the number of carbon particles floating in the vacuum chamber 1 , the number of particles adhering to the surface of the substrate W can be reduced as much as possible. In this case, since the adsorption body 7 is arranged at a specific position in the vacuum chamber where radiation to the substrate W is prevented, it does not occur due to the film formation process for the substrate W such as a change in film quality. the problem of adverse effects. In addition, by cooling the shielding plate 5 itself to a temperature of 123 K or less by the radiation from the adsorbent 7, the shielding plate 5 itself functions as an adsorbent, and by partitioning the film-forming space 1b The shielding plate 5 adsorbs and holds the carbon particles, and the amount of the floating carbon particles can be further reduced, which is advantageous. In this case, it is desirable to separate the substrate W and the shielding plate 5 by 10 mm or more so that the substrate W is not cooled due to radiation from the cooled shielding plate 5 .

400mm之碳製之物，並且使用上述濺鍍裝置SM，來對於基板W成膜了碳膜。作為濺鍍條件，係將靶材2與基板W之間之距離設為60mm，並將由濺鍍電源E所致之投入電力設為2kW，並且將濺鍍時間設定為120秒。又，作為濺鍍氣體，係使用氬氣，於濺鍍中，係將濺鍍氣體之分壓設為0.1Pa。又，作為比較實驗，係從上述濺鍍裝置SM而將吸附體7卸下，並以相同 之條件來進行了成膜。 Next, in order to confirm the effect of this invention, the following invention experiment was performed. That is, the substrate W is a silicon wafer with a diameter of 300 mm, and the target 2 is

A carbon film of 400 mm was formed on the substrate W using the above-mentioned sputtering apparatus SM. As sputtering conditions, the distance between the target 2 and the substrate W was set to 60 mm, the input power by the sputtering power supply E was set to 2 kW, and the sputtering time was set to 120 seconds. In addition, argon gas was used as a sputtering gas, and the partial pressure of the sputtering gas was set to 0.1 Pa in the sputtering. In addition, as a comparative experiment, the adsorption|suction body 7 was removed from the said sputtering apparatus SM, and film formation was performed under the same conditions.

The number of particles of 0.1 μm or more adhering to the substrate W before and after the film formation was measured to obtain the number of particles adhering to the substrate W during the film formation. Based on this, in the invention experiment, the number was 84, while in the comparative experiment, it was 145, and it was found that the number of particles can be reduced by providing the adsorbent 7 .

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described configuration. In the above-described embodiment, the outer surface portion 52a of the lower plate portion 52 of the shielding plate 5 in the range facing the exhaust gas inflow port 11b of the exhaust space portion 11 is covered with a gap therebetween. The adsorption body 7 is provided, however, as shown in FIG. 3 , the two ends of the adsorption plate 7 can be further extended to the gap between the inner wall surface 1 a of the vacuum chamber 1 and the lower plate portion 52 of the shielding plate 5 . in the method to make settings. In addition, in FIG. 3, arrows represent the flow of the exhaust gas. According to this, the shielding plate 5 can be efficiently cooled, and the carbon particles contained in the exhaust gas can be adsorbed and held efficiently, and thereby, the exhaust gas can be It is advantageous to suppress that the carbon particles in the film flow into the film-forming space 1b and adhere to the substrate W.

In the above-mentioned embodiment, the case where the shielding plate 5 is cooled by the adsorbent 7 has been described as an example, however, even if the cooling is performed on the matter adhering to the carbon particles of the components other than the shielding plate 5 In this case, the present invention can also be applied.

1‧‧‧Vacuum chamber

1a‧‧‧Inner wall of vacuum chamber 1

1b‧‧‧Film-forming space

2‧‧‧Target

3‧‧‧Magnet Unit

4‧‧‧Platform

5‧‧‧Shielding plate

6‧‧‧Gas introduction means

7‧‧‧Adsorbent

7a‧‧‧Lifting mechanism

11‧‧‧Exhaust space

11a‧‧‧Exhaust port

11b‧‧‧Exhaust gas inlet

21‧‧‧Bezel

22‧‧‧Sputtering surface

51‧‧‧Top plate

52‧‧‧Lower plate

52a‧‧‧Outer surface part

61‧‧‧Gas ring

61a‧‧‧Gas injection port

62‧‧‧Gas Pipe

63‧‧‧Mass Flow Controller

Ib‧‧‧Insulator

E‧‧‧Sputtering Power Supply

C1‧‧‧Centerline

Cu‧‧‧Cathode unit

SM‧‧‧Sputtering Equipment

Vp‧‧‧Vacuum pump

W‧‧‧Substrate (object for film formation)

Claims (3)

A sputtering apparatus comprising: a vacuum chamber provided with a carbon-made target, a vacuum pump for evacuating the vacuum chamber, a stage for holding a film-forming object in the vacuum chamber, and a vacuum pump The inner wall of the cavity is provided with a gap and a shielding plate that surrounds the film-forming space between the target and the platform, and after the vacuum pump is used to evacuate the vacuum cavity to a specific pressure, The target is sputtered to form a carbon film on the surface of the film-forming object. The sputtering apparatus is further provided with an adsorbent for cooling the surface to a temperature of 123 K or less. The adsorbent, It is installed at a specific position in the vacuum chamber where heat radiation to the film-forming object is prevented, and there is a gap in the outer surface portion of the shielding plate. The sputtering apparatus according to claim 1, wherein the target and the platform are arranged to face each other, and an exhaust space portion is provided, and the exhaust space portion is positioned opposite to the target material. The extension line connected to the platform is partially protruded in a direction orthogonal to the above-mentioned vacuum pump, and the above-mentioned vacuum pump is connected to the exhaust port opened in the exhaust space portion. The sputtering apparatus according to claim 2, wherein the outer surface portion of the shielding plate is provided in a range facing the exhaust gas inflow port of the exhaust space portion.

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