JP2019052359A - Sputtering apparatus and thin film manufacturing method - Google Patents

Abstract

Disclosed is a sputtering apparatus that prevents adhesion of a dielectric material to a deposition plate that is an anode electrode, reduces the effective area of the anode electrode, and does not reduce the growth rate of a thin film.
A low resistance film 7 formed by thermal spraying of Al is provided on the surface of a deposition preventing plate 17 surrounding a sputtering space 12 sandwiched between a sputtering target 16 and a substrate placement portion 13. A sputtering apparatus in which Li and Al from Li ₃ PO ₄ sputtered particles adhering to the surface form an alloy to reduce the resistance of the adhesion film formed on the deposition preventing plate 17.
[Selection] Figure 1

Description

  The present invention relates to a technology of a sputtering apparatus, and more particularly to an RF sputtering apparatus and a thin film manufacturing method for forming a LiPON thin film.

  Conventionally, an RF sputtering method has been used to form a dielectric thin film. In the RF sputtering method, a thin film is formed using a dielectric material that cannot be formed by a DC sputtering method or the like as a sputtering target. At the time of RF sputtering, a high frequency voltage is applied between an anode electrode and a backing plate on which a sputtering target is disposed as a cathode electrode, and a sputtering target of a dielectric material is sputtered.

By the way, in the inside of the vacuum chamber of the sputtering apparatus, in order to prevent an adhesion film from being deposited on components such as an inner wall surface of the vacuum chamber and a sensor disposed in the vacuum chamber, a deposition plate is disposed, When the deposited adhesion film grows to a certain thickness, it is removed and reused. The deposition preventing plate is taken out of the vacuum chamber and the adhesion film is removed.
Therefore, a strong metal material such as stainless steel is used for the deposition preventing plate.

  Since no other member is disposed between the deposition preventing plate and the sputtering target and the deposition preventing plate is made of metal, a deposition preventing plate is generally used for the anode electrode. ing.

  Since the sputtering target is a dielectric material and the thin film to be formed is also a dielectric, the adhesion film deposited on the adhesion-preventing plate by sputtering is also a dielectric, and when the film thickness value of the adhesion film increases, the anode electrode The effective area decreases, and the discharge becomes unstable and the deposition rate on the substrate decreases due to insufficient anode electrode area.

  With respect to such an anode area reduction phenomenon, there is a countermeasure in the prior art that ensures a certain anode area or more by forming a region on the surface of the anode electrode where particles sputtered from the sputtering target do not adhere. In many cases, the structure is complicated, and an increase in the number of parts, cost increase, and limitation of the chamber structure are problems.

JP 2013-122080 A Japanese Patent Laying-Open No. 2015-093996

  The inventors of the present invention use a deposition plate whose surface is coated with an Al thin film when depositing LiPON, which is one of solid electrolyte materials for Li secondary batteries, on a substrate by RF sputtering. As a result, it has been found that when a LiPON thin film is formed on a plurality of substrates, a decrease in the deposition rate is suppressed.

When the adhesion prevention board was taken out from the vacuum chamber and the resistance value of the adhesion film formed on the surface was confirmed, it was found that it was smaller than the resistance value of the adhesion film normally measured.
If so, it is considered that the amount of decrease in the effective area of the anode electrode has been reduced by reducing the resistance of the adhesion film formed on the deposition preventing plate.

  The present invention is an invention created based on the above findings, and an object of the present invention is to provide a LiPON thin film sputtering apparatus having a high film formation rate.

It was found that the decrease in the film formation rate was suppressed by coating Al reacting with LiPON on the SUS-made deposition plate (conventional: 14.9 nm / min⇒Al coating: 17). .1 nm / min).
After the film formation, the chamber was opened and the resistance value on the adhesion-preventing plate was confirmed. As a result, it was found that the attached film had a low resistance.

The present invention was created based on the above knowledge, and the present invention includes a vacuum chamber, a backing plate disposed in the vacuum chamber, a sputtering target provided in the backing plate, and the vacuum chamber. And a sputtering space between the sputtering target and the substrate placement portion, a substrate placement portion on which a film formation target is placed, a sputtering power source that applies an AC voltage having a frequency of 2 MHz or more to the backing plate, and The sputtering target is a dielectric containing Li, and when the sputtering target is sputtered by a sputtering gas, the film-forming target placed on the substrate placement portion A sputtering apparatus in which a thin film containing Li is formed on the surface, On the surface facing the sputtering space of the deposition preventing plate, a sputtering apparatus low resistance film containing a metal that forms a Li alloy is formed.
In the present invention, the low resistance film may be a metal film made of one of Al and Mg.
In the present invention, the low resistance film may be an aluminum sprayed film formed by spraying aluminum.
In the present invention, the sputtering target may be Li ₃ PO ₄ formed into a plate shape.
Moreover, this invention arrange | positions the film-forming target object in the board | substrate arrangement | positioning part provided in the vacuum chamber, applies the alternating voltage of a frequency of 2 MHz or more to the backing plate arrange | positioned in a vacuum chamber, Sputtering a sputtering target, which is a dielectric that contains Li, and sputtered particles sputtered from the sputtering target, the surface of the film formation target disposed in the substrate placement portion, the sputtering target and the substrate placement A thin film manufacturing method for forming a thin film containing Li on the surface of the film formation target object, wherein the surface of the deposition target is formed on the surface of the film formation target object. A low resistance film containing a metal that forms an alloy with Li is formed on the surface facing the sputter space, and reaches the deposition preventing plate. Said sputtered particles are deposited in the low resistance film that, the lower the resistance value than the thin film, a thin film manufacturing method for forming an alloy of the metal and Li in the deposition preventing plate surface.
Further, the present invention is a thin film manufacturing method using a metal film made of one of Al and Mg as the low resistance film.
The present invention is also a thin film manufacturing method using an aluminum sprayed film formed by spraying aluminum on the low resistance film.
Further, the present invention is the sputtering target is a thin film manufacturing method using the Li ₃ PO ₄ that is formed in a plate shape.

  In the technique for producing a dielectric film by the RF sputtering method, securing the anode area is a very important factor. Until now, it was a countermeasure only with a hard structure, but there were many devices with a structure in which the structure in the actual chamber was limited and stable discharge was not possible.

  The technique for solving the problem by changing the adhesion film itself as in the present invention is a useful technique because it can be solved even when it cannot be solved by a hard structure. In the present invention, the film formation in which a LiPON thin film is formed is used. Even if the number of objects increases, the deposition rate of the LiPON thin film does not drop significantly.

Sputtering apparatus according to an example of the present invention

FIG. 1 is an internal side view of a sputtering apparatus 2 according to an example of the present invention, and the sputtering apparatus 2 has a vacuum chamber 11.
Inside the vacuum chamber 11, there is provided a substrate placement portion 13 including a substrate holder for holding the substrate and a table on which the substrate is placed. The target device 14 is arranged.

  The target device 14 includes a backing plate 15 and a sputtering target 16 fixed to the backing plate 15, and the target device 14 is arranged so that the surface of the sputtering target 16 faces the substrate placement unit 13. .

  An RF power source 23, a sputtering gas source 26, and a vacuum exhaust device 27 are disposed outside the vacuum chamber 11. The inside of the vacuum chamber 11 is evacuated by a vacuum evacuation device 27 to form a vacuum atmosphere. While maintaining the vacuum atmosphere, a film formation target is carried into the vacuum chamber 11 and placed on the substrate placement unit 13. Then, a sputtering gas is introduced into the vacuum chamber 11 from the sputtering gas source 26. A reference numeral 10 in FIG.

  Next, when a high-frequency voltage is applied from the RF power source 23 to the backing plate 15 using the backing plate 15 as a cathode electrode, sputtering gas plasma is formed in the vicinity of the surface of the sputtering target 16, and the sputtering target 16 is sputtered. Sputtered particles jump out of the surface of 16.

  In the present invention, a high frequency voltage of 2 MHz or higher is applied to the backing plate 15. A magnetron magnet 19 is disposed behind the backing plate 15, and magnetron sputtering is performed in the sputtering apparatus 2.

  Sputtered particles that have jumped out of the surface of the sputtering target 16 fly through the sputtering space 12 that is a space sandwiched between the sputtering target 16 and the substrate placement portion 13, reach the surface of the film formation target 10, and reach the surface of the film formation target 10. A thin film is grown on the surface.

A ground electrode plate 18 and a deposition preventing plate 17 are disposed inside the vacuum chamber 11.
The ground electrode plate 18 and the adhesion preventing plate 17 have a ring shape, and the target device 14 is arranged in a region surrounded by the ground electrode plate 18, that is, the target device 14 is surrounded by the ground electrode plate 18. The discharge on the side surface of the target device 14 is prevented.

  Similarly, the sputter space 12 is surrounded by an adhesion prevention plate 17 so that the sputtered particles that have jumped out from the surface of the sputtering target 16 do not reach the inner wall surface of the vacuum chamber 11 or the members disposed inside the vacuum chamber 11. Has been.

  The deposition preventing plate 17 and the ground electrode plate 18 are in contact with the vacuum chamber 11 so as to have the same potential as the vacuum chamber 11, and since the vacuum chamber 11 is connected to the ground potential, The ground electrode plate 18 is placed at a ground potential together with the vacuum chamber 11. Since the deposition preventive plate 17 faces the sputter space 12, when the high frequency voltage is applied to the target device 14, the deposition preventive plate 17 is used as an anode electrode.

The deposition preventing plate 17 and the ground electrode plate 18 are each made of stainless steel, and at least a portion of the surface of the deposition preventing plate 17 and the surface of the ground electrode plate 18 facing the sputter space 12. On the portion of the ground electrode plate 18 facing the target device 14, low resistance films 7 and 8 are formed, respectively.
As a result, the sputtered particles that jump out of the sputtering target 16 and fly in the direction of the deposition preventing plate 17 reach the surface of the low resistance film 7.

In this sputtering apparatus 2, a dielectric containing Li, P, and O is used for the sputtering target 16, and a part of Li ₃ PO ₄ is nitrided on the surface of the film formation target 10. A LiPON thin film (LiPON thin film) is formed. Specifically, a plate of Li ₃ PO ₄ is used here for the sputtering target 16. This sputtering target 16 has a resistivity of 1 kΩ · cm or more.

  Further, nitrogen gas is used as the sputtering gas, and a plasma of nitrogen gas is formed on the surface of the sputtering target 16, and the substance constituting the sputtering target 16 and nitrogen react chemically to bring nitrogen into the chemical structure. A thin film of the compound is formed as a LiPON thin film on the surface of the film formation target 10. In this embodiment, the sputtering gas does not contain a rare gas such as argon gas, but the rare gas may also be contained within a predetermined range.

  By the way, it is known that metals such as Fe, Cu, Ni, and Ti do not form an alloy with Li, whereas metals such as Al and Mg form an alloy with Li. In the present invention, the low resistance film 7 made of an Al film is formed on the surface of the deposition preventing plate 17, and Li is contained in the low resistance film 7 from the sputtering particles containing Li adhering to the surface of the low resistance film 7. An adhesion film is formed on the surface of the low resistance films 7 and 8 by the residue after diffusion of Li. The residue after Li diffusion has a lower resistance than the LiPON thin film.

  Since the surface of the film formation target 10 does not contain Al or Mg, Li does not diffuse from the sputtering particles attached to the surface of the film formation target 10, and Li decreases on the surface of the film formation target 10. No, a LiPON film grows. The LiPON thin film has a higher resistance than the deposited film formed on the low resistance films 7 and 8 by the residue after Li diffusion.

  As the low resistance films 7 and 8, an Al thin film formed by a vapor deposition method or a sputtering method can be used, but an Al sprayed film formed by spraying Al on the surface of the deposition preventing plate 17 is used as the low resistance film 7. If it is provided on the surface of the deposition preventing plate 17, the surface area of the low resistance film 7 is increased, the amount of Li diffused into the low resistance film 7 is increased, and the resistance of the adhesion film is reduced. As a result, the effective area of the anode electrode is prevented from being reduced. As a result, even if the number of deposition objects 10 on which the LiPON film is formed increases, the decrease in the growth rate of the LiPON thin film on the deposition object 10 is alleviated. .

  According to the experiment, when the deposition preventing plate 17 on which the low resistance reducing film 7 is not formed is used as the anode electrode, the deposition rate (thin film growth thickness on the deposition target surface per unit time) is 14.9 nm / On the other hand, when the deposition plate 17 having the Al sprayed film formed on the surface as the low resistance film 7 is used as the anode electrode, a thin film growth rate of 17.1 nm / min is obtained. It can be seen that the reduction in the effective area of the anode electrode is prevented by reducing the resistance of the film.

  It is expected that such an effect can be obtained when the low resistance film 7 containing a metal that forms an alloy with Li is formed on the surface of the deposition preventing plate 17. Specifically, in addition to the Al film, Mg A film or an alloy film containing Al and Mg is conceivable.

  Even if the low resistance films 7 and 8 are not high resistance and are formed on the ground electrode plate 18, sputtering of the side surfaces of the sputtering target 16 and the backing plate 15 is prevented.

  Here, a low resistance film 8 having the same composition as that of the low resistance film 7 formed on the adhesion preventing plate 17 is also formed on the surface of the ground electrode plate 18, and the effective effect of the ground electrode plate 18 by the adhesion film is formed. A reduction in area is also prevented. Stable sputtering can be performed also by the low resistance film 8 formed on the surface of the ground electrode plate 18.

2 ... Sputtering device 7 ... Low resistance film 10 ... Deposition target 11 ... Vacuum chamber 13 ... Substrate placement portion 15 ... Backing plate 16 ... Sputtering target 17 ... Anti-adhesion plate 23 ... RF Power supply 26 …… Sputtering gas source

Claims (8)

A vacuum chamber;
A backing plate disposed in the vacuum chamber;
A sputtering target provided on the backing plate;
A substrate placement portion provided in the vacuum chamber and on which a film formation target is placed;
A sputtering power source for applying an AC voltage having a frequency of 2 MHz or more to the backing plate;
An adhesion preventing plate surrounding a sputtering space between the sputtering target and the substrate placement portion;
Have
The sputtering target is a dielectric containing Li,
When the sputtering target is sputtered by a sputtering gas, a sputtering apparatus in which a thin film containing Li is formed on the surface of the film formation target disposed in the substrate placement portion,
A sputtering apparatus in which a low resistance film containing a metal that forms an alloy with Li is formed on a surface of the deposition preventing plate facing the sputtering space.   The sputtering apparatus according to claim 1, wherein the low resistance film is a metal film made of any one of Al and Mg.   The sputtering apparatus according to claim 1, wherein the low resistance film is an aluminum sprayed film formed by spraying aluminum. The sputtering apparatus according to claim 1, wherein the sputtering target is Li ₃ PO ₄ formed into a plate shape. Place the film formation target on the substrate placement part provided in the vacuum chamber,
An alternating voltage having a frequency of 2 MHz or more is applied to a backing plate disposed in a vacuum chamber, a sputtering target that is a dielectric containing Li provided on the backing plate is sputtered, and sputtered particles that have jumped out of the sputtering target And reaching the surface of the deposition target disposed on the substrate placement section and the surface of the deposition plate surrounding the sputtering space between the sputtering target and the substrate placement section, A thin film manufacturing method for forming a thin film containing Li on the surface of
A low-resistance film containing a metal that forms an alloy with Li is formed on the surface of the deposition plate facing the sputter space, and the sputtered particles that reach the deposition plate are reduced in the low resistance. A thin film manufacturing method in which an alloy of the metal and Li having a lower resistance value than that of the thin film is formed on the surface of the deposition preventing plate.   6. The thin film manufacturing method according to claim 5, wherein a metal film made of one of Al and Mg is used for the low resistance film.   The thin film manufacturing method according to claim 5, wherein an aluminum sprayed film formed by spraying aluminum is used for the low resistance film. The thin film manufacturing method according to any one of claims 5 to 7, wherein Li ₃ PO ₄ formed into a plate shape is used for the sputtering target.

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