TW201903180A - Sputtering device - Google Patents

Abstract

The present invention is to provide a sputtering apparatus capable of minimizing the number of particles adhering to the surface of a film-formed object. The sputtering apparatus (SM) of the present invention comprises: a vacuum chamber (1) provided with a carbon target (2), a vacuum pump (Vp) for vacuum evacuating the vacuum chamber, and a stage (4) for holding a film-formed object (W) in a vacuum chamber. After vacuum evacuating the vacuum chamber to a specific pressure by the vacuum pump, the target is sputtered, thereby forming a carbon film on the surface of the film-formed object, and the sputtering apparatus (SM) further has an absorbent (7) having a temperature at which the surface is cooled to 123K or less, and the absorbent is disposed at a specific position in the vacuum chamber where the radiation with respect to the film-formed object is prevented from.

Description

Sputtering device

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

In the prior art, such a sputtering apparatus is used to form a carbon film as an electrode film of a non-volatile memory or the like (for example, refer to Patent Document 1). Such a sputtering device includes a vacuum chamber provided with a carbon target, a vacuum pump that evacuates the vacuum chamber, and a vacuum chamber that is disposed opposite the target and holds a film-forming object. Things platform. In the vacuum chamber, a shielding plate is provided. The shield 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 platform. Then, a vacuum pump is used to evacuate the inside of the vacuum chamber to a specific pressure, and then a target is subjected to sputtering to form a carbon film on the surface of the film formation object.

Here, when a carbon target is sputtered and a film is formed on the surface of the film formation object, fine particles may adhere to the surface of the film formation object immediately after the film formation. . Since the adhesion of such particles causes a reduction in the yield of the product, it is necessary to suppress the adhesion of particles to the surface of the film formation object as much as possible. Therefore, the present inventors have made diligent research and found the following knowledge: that is, carbon particles floating in a vacuum chamber are adhered to the film just after being formed as fine particles. On the surface of the object. That is, it can be presumed that this is due to the fact that if a carbon target is sputtered, the carbon particles scattered from the target are not only attached to the film-forming object, but also It will adhere and accumulate on the surface of the parts and shielding plates that exist around the target, but the carbon particles that are attached in this way will be detached again for some reason, and the carbon particles that are detached again The system is not vacuum evacuated, but floats in the vacuum chamber. [Prior Art Literature] [Patent Literature]

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

[Problems to be Solved by the Invention]

The present invention has been made based on the above-mentioned knowledge, and an object thereof is 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. [Means to solve the problem]

In order to solve the above-mentioned problem, the sputtering apparatus of the present invention includes a vacuum chamber provided with a carbon target, a vacuum pump for vacuum-evacuating the vacuum chamber, and a film-forming object held in the vacuum chamber. After the target is vacuumed and the vacuum chamber is evacuated to a specific pressure by vacuum pumping, the target is sputtered, and thereby a carbon film is formed on the surface of the film-forming object. The plating device is characterized in that it further includes an adsorbent for cooling the surface to a temperature of 123 K or less, and the adsorbent is disposed at a specific position in a vacuum chamber for preventing radiation of a film-forming object. Office.

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, the situation of re-detachment is prevented. 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-forming 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 that prevents the radiation of the film-forming object, the film-forming process for the film-forming object will not occur, such as changing the film quality. Problems caused by adverse effects.

In the present invention, when the target material and the platform are oppositely disposed, and the exhaust space portion is partially bulged in a direction orthogonal to an extension line connecting the two, The above-mentioned vacuum pump is connected to an exhaust port provided in the exhaust space section, and the sputtering device is provided with a gap from the inner wall surface of the vacuum chamber and is provided. In the case where the film-forming space between the target and the platform is a surrounding shielding plate, it is preferable that the above-mentioned adsorbent is arranged at the outer surface portion of the shielding plate with a gap. According to this, the shielding plate itself is cooled to a specific temperature by the radiation from the adsorbent, and the shielding plate itself functions as an adsorbent, and the shielding plate is used to partition the film forming space. Carbon particles are adsorbed and held, and the amount of floating carbon particles can be further reduced, which is advantageous.

In this case, it is preferable that the outer surface portion of the shielding plate is set to a range relatively opposed to the exhaust gas inlet of the exhaust space portion. According to this, the presence of the adsorbent in the exhaust path of the exhaust gas from the film-forming space in the vacuum chamber to the exhaust space portion enables the carbon particles to be more easily adsorbed, and As favorable.

In the following, referring to the drawings, a silicon wafer (hereinafter simply referred to as "substrate W") is used as a film formation target, and a carbon target for sputtering is provided above the vacuum chamber, and a substrate As an example, a platform provided with a substrate W will be described as an embodiment of the sputtering apparatus of the present invention.

Referring to FIG. 1 and FIG. 2, SM is a sputtering device of a magnetron method according to an embodiment of the present invention. The sputtering device SM is provided with a vacuum chamber 1, and a cathode unit Cu is detachably mounted on an upper portion of the vacuum chamber 1. The cathode unit Cu is composed of a carbon target 2 and a magnet unit 3 disposed above the target 2.

The target 2 is formed in a circular shape in plan view in accordance with the contour of the substrate W. The target 2 is mounted on the baffle 21 with its sputtered surface 22 facing downward, and is mounted on the vacuum chamber 1 via an insulator Ib provided on the upper wall of the vacuum chamber 1. On the top. In addition, a sputtering power source E having a known structure is connected to the target 2 and is configured to be capable of inputting DC power having a negative potential when a film is formed by sputtering. The magnet unit 3 disposed above the target 2 generates a magnetic field in a space below the sputtering surface 22 of the target 2 and is ionized below the sputtering surface 22 during sputtering. Electron or the like is provided with a latching magnetic field or a cusp magnetic field structure for capturing and efficiently ionizing the sputtered particles scattered from the target 2. As the magnet unit itself, a well-known structure can be used. Therefore, further detailed description is omitted.

In the center of the bottom of the vacuum chamber 1, a platform 4 is disposed opposite to the target material 2 with other insulators Ib interposed therebetween. Although the platform 4 is not particularly shown and described, it 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 film formation, the substrate W can be adsorbed and held. In addition, since the structure of the electrostatic chuck is a known structure such as a unipolar type or a bipolar type, further detailed description is omitted here. In addition, a passage or a heater for circulating a refrigerant may be built in the abutment, and the substrate W may be controlled to a specific temperature during film formation.

In the vacuum chamber 1, a shielding plate 5 is provided. The shield plate 5 is provided with a gap from the inner wall 1 a of the vacuum chamber 1 and surrounds the film forming space 1 b between the target 2 and the platform 4. The shielding plate 5 is provided with a slightly cylindrical upper plate portion 51 that surrounds the periphery of the target 2 and extends below the vacuum chamber 1, and a slightly cylinder that surrounds the periphery of 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 integrally formed, or the system 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 a gas introduction means 6 for introducing a specific gas. The gas includes not only a rare gas such as argon gas which is introduced when a plasma is formed in the film forming space 1b, but also a reaction gas such as oxygen or nitrogen which is suitably introduced in accordance with the film formation. The gas introduction means 6 includes a gas ring 61 provided on the outer periphery of the upper plate portion 51, and a gas pipe 62 penetrating the side wall of the vacuum chamber 1 connected to the gas ring 61. The gas pipe 62 is connected via The mass flow controller 63 is connected to a gas source (not shown). In this case, although a detailed illustration is omitted, a gas diffusion section is attached to the gas ring 61, and the sputtering gas system from the gas pipe 62 is diffused by the gas diffusion section and becomes a slave. At the gas ring 61, the gas injection ports 61a provided at regular intervals in the circumferential direction penetrate the sputtering gas at the same flow rate. The sputtering gas sprayed from the gas injection port 61a is introduced into the film formation space 1b at a specific flow rate from a gas hole (not shown) formed in the upper plate portion 51, and is formed in the film formation. In this case, the pressure distribution in the film forming space 1b can be made equal to cover the entire area. In addition, the same method for covering the entire pressure distribution in the film-forming space 1b is not limited to this, and other known methods can be suitably used.

Further, the vacuum chamber 1 is provided with an exhaust space portion 11 that partially bulges in a direction orthogonal to the center line (extension line) Cl connecting the target 2 and the platform 4. An exhaust port 11a is opened on the bottom wall surface of the exhaust space portion 11 to define the exhaust space. The exhaust port 11a is a vacuum pump Vp connected to a cryopump, a turbo molecular pump, or the like via an exhaust pipe. During the film formation, a part of the sputtering gas introduced into the film formation space 1b becomes an exhaust gas, and passes from the joint portion of the shielding plate 5 and the gap between the shielding plate 5 and the target 2 or the platform 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 is directed toward the vacuum helper via the exhaust port 11a Pump Vp for vacuum exhaust. At this time, a pressure difference between the film formation space 1b and the exhaust space portion 11 is about several Pa.

In the case where the substrate W is formed into a specific thin film, the substrate W is transferred to the platform 4 by a vacuum transfer robot (not shown), and the substrate W is set on the suction plate of the platform 4 (in this case) The upper surface of the substrate W becomes a film-forming surface). After that, the vacuum transfer robot is retracted, and a specific voltage is applied from the chuck power source to the electrode for the electrostatic chuck to electrostatically adsorb the substrate W on the chuck plate. Then, if the inside of the vacuum chamber 1 a vacuum evacuated to the prescribed pressure ^{(e.g., 1 × 10 - 5 Pa)} , then the system through the gas introduction means 6 to the gas constant of the flow rate introduced into the argon as sputtering gases, and Specific power is input to the target 2 from the sputtering power source E. As a result, a plasma is formed in the film forming space 1b, and the target material is sputtered by the argon ions in the plasma, and the sputtered particles (carbon particles) from the target 2 are adhered. On the substrate W, a carbon film is formed. In the case where the target material 2 was sputtered and a carbon film was formed as described above, it was found that the carbon particles floating in the vacuum chamber 1 were attached as fine particles to the composition immediately after the film formation. On the surface of the film object. It can be presumed that this is due to the fact that the carbon particles scattered from the target are not only attached to the substrate W, but also attached to and deposited on the parts 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 due to some reasons. The carbon particles that are detached again are not evacuated in vacuum, but are in the vacuum chamber 1. Floating.

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

According to the above structure, once the carbon particles floating in the vacuum chamber 1 are adsorbed on the adsorbent body 7, the surface of the adsorbent body 7 is cooled to a temperature below 123K, so the situation of re-detachment is prevented. . 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 adsorbent 7 is disposed at a specific position in the vacuum chamber in which the radiation to the substrate W is prevented, it is not caused by the film-forming process for the substrate W, such as a change in film quality. Problem of adverse effects. In addition, the shielding plate 5 itself is cooled to a temperature of 123K or less by the radiation from the adsorption body 7. The shielding plate 5 itself functions as an adsorption body, and by dividing the film forming space 1b The shielding plate 5 absorbs carbon particles and holds them, and the amount of floating carbon particles can be further reduced, which is advantageous. In this case, it is desirable to separate the substrate W from the shielding plate 5 by 10 mm or more so as not to cool the substrate W due to radiation from the cooled shielding plate 5. .

Next, in order to confirm the effect of the present invention, the following invention experiments were performed. That is, the substrate W is made of a silicon wafer having a diameter of 300 mm, and the target 2 is made of carbon of φ400 mm, and a carbon film is formed on the substrate W using the sputtering device SM described above. As the sputtering conditions, the distance between the target 2 and the substrate W was set to 60 mm, the input power caused by the sputtering power source E was set to 2 kW, and the sputtering time was set to 120 seconds. Also, as the sputtering gas, argon gas was used, and during the sputtering, the partial pressure of the sputtering gas was set to 0.1 Pa. In addition, as a comparative experiment, the adsorbent 7 was detached from the 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 film formation was measured, and the number of particles adhering to the substrate W during film formation was obtained. According to this, in the invention experiment, the number is 84, while in the comparison experiment, it is 145. It can be seen that by providing the adsorbent 7, the number of particles can be reduced.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said structure. In the embodiment described above, the outer surface portion 52a of the lower plate portion 52 of the shielding plate 5 in a range facing the exhaust gas inflow port 11b of the exhaust space portion 11 is covered with gaps. The adsorption body 7 is provided, but it can also be as shown in FIG. 3, so that both ends of the adsorption plate 7 further extend between the inner wall surface 1a of the vacuum chamber 1 and the lower plate portion 52 of the shielding plate 5. The way to set in the gap. In FIG. 3, arrows indicate 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 efficiently adsorbed and held, and thus, the exhaust gas can be cooled. It is advantageous that the carbon particles in the film formation space 1b flow onto the substrate W to suppress the occurrence of the carbon particles on the substrate W.

In the embodiment described above, the case where the shielding plate 5 is cooled by the adsorbent 7 is described as an example, but even if the carbon particles constituting parts other than the shielding plate 5 are cooled, In the case of the present invention, the present invention can also be applied.

SM‧‧‧Sputtering Device

Vp‧‧‧Vacuum Pump

W‧‧‧ substrate (film formation object)

1‧‧‧vacuum chamber

1a‧‧‧Inner wall surface of vacuum chamber 1

11‧‧‧Exhaust space department

11a‧‧‧ exhaust port

2‧‧‧ Target

4‧‧‧ platform

5‧‧‧shield

7‧‧‧ adsorbent

[Fig. 1] A schematic cross-sectional view showing a sputtering apparatus according to an embodiment of the present invention. [Fig. 2] is a sectional view taken along line II-II in Fig. 1. [Fig. 3] is a diagram showing a modified example of this embodiment.

Claims (3)

A sputtering device is provided with a vacuum chamber provided with a carbon target, a vacuum pump for evacuating the vacuum chamber, and a platform for holding a film-forming object in the vacuum chamber. After the vacuum pump is used to evacuate the vacuum chamber to a specific pressure, sputtering is performed on the target, thereby forming a carbon film on the surface of the film formation object. The sputtering device is characterized by: The system further includes an adsorbent for cooling the surface to a temperature of 123 K or less, and the adsorbent is disposed at a specific position in a vacuum chamber for preventing radiation of a film-forming object. The sputtering device described in item 1 of the scope of the patent application, wherein the target is arranged opposite to the platform, and an exhaust space section is provided. The exhaust space section is opposed to the two. The connected extension lines swell locally in orthogonal directions. The exhaust ports provided in the exhaust space section are connected with the aforementioned vacuum pumps, and are provided with a vacuum chamber. A shielding plate is provided on the inner wall surface with gaps and the film-forming space between the target and the platform is surrounded. The aforementioned adsorbent is attached to the outer surface of the shielding plate and is provided with gaps. . The sputtering device according to item 2 of the scope of the patent application, wherein is a range in which the outer surface portion of the shielding plate is opposed to the exhaust gas inlet of the exhaust space portion.