JP2008081820A - Film deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film deposition system capable of suppressing generation of wrinkles of a base sheet attributable to the thermal expansion caused by the temperature rising during the film deposition. <P>SOLUTION: The film deposition system 10 comprises: a gas particle generation unit 13 for generating vapor of lithium or the like to perform the vacuum vapor deposition; a roll 33 being a conveying and supporting member for movably supporting the base sheet 31 with gas particles deposited thereon; a deposition preventive plate 36 for limiting the flight of the gas particles; and a lamp heater 40 for heating the base sheet 31 before the base sheet 31 is brought into contact with the roll 33. The occurrence of wrinkles of the base sheet 31 on the roll 33 is suppressed by heating and thermally expanding the base sheet 31 by the lamp heater 40 before the base sheet 31 is heated by a heating mechanism of the gas particles and the gas particle generation unit 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a film forming apparatus for forming a film of an inorganic material such as a metal, a metal oxide, or a metal nitride, and more particularly to measures for facilitating the film forming operation.

  In recent years, the number of products that use parts made of base material sheets with films made of functional inorganic materials such as metals, metal oxides, and metal nitrides has been increasing. Development of products such as lithium secondary batteries having a structure in which a positive electrode film or a lithium metal film is wound in a cylindrical shape is underway. For example, lithium secondary batteries that use lithium metal as the negative electrode material can achieve high energy density per unit weight and per unit volume. With the advancement of mobile phones, mobile devices such as notebook computers and PDAs, etc. It is possible to cope with higher density of batteries. In such a product manufacturing process, a process of forming a film of a material containing a metal on a base sheet is a particularly important process, and various proposals have been made conventionally.

In Patent Document 1 and Patent Document 2, as a film forming apparatus for forming a thin film on a substrate such as a PET sheet or a metal foil, the diameter of the can roll of the film forming apparatus is large at the center portion and both end portions. A small diameter, that is, a drum shape (crown shape) is known.
JP-A-7-065373 JP-A-10-008249

  When depositing a thin film on a base sheet such as a PET sheet, gas particles that have become hot due to vacuum heating or the like are deposited on the base sheet, so the temperature difference between the hot deposit and the base sheet, etc. As a result, wrinkles may occur in the base sheet. That is, when the base sheet is in contact with the can roll, the base sheet receives a drag due to the contact with the can roll. Therefore, even if trying to expand, the movement of the base sheet in the width direction is limited by the frictional force. . In the wrinkled portion, the thickness of the deposited thin film varies, which may cause a product defect. In particular, when the base sheet is made of an inorganic material such as copper foil, there is a problem that wrinkles remain as plastic deformation.

  In Patent Document 1, by increasing the diameter of the central portion of the can roll corresponding to the central portion of the PET sheet where wrinkles are likely to occur, the contact area is increased, cooling efficiency is increased, and thermal expansion is suppressed. Is disclosed to prevent the generation of wrinkles (see paragraph [0007]). However, this concept does not apply to a base sheet such as a metal foil with low flexibility. On the other hand, in Patent Document 2, when using a metal foil that is less flexible than a PET sheet, at both ends of the crown-shaped can roll, the degree of contact between the metal foil and the can roll is weakened, whereby the substrate It is described that the sheet can easily slide in the width direction and wrinkle generation can be suppressed (see paragraph [0008]).

  However, even if the technique of Patent Document 2 is used, by forming the can roll into a crown shape, the drag received from the can roll concentrates on the central portion of the base sheet with low flexibility, resulting in thermal expansion of the base sheet. The frictional force that hinders movement also increases. As a result, there is one aspect in which the generation of wrinkles is increased, and it has been difficult to reliably prevent the generation of wrinkles by the technique of Patent Document 2.

  An object of the present invention is to reduce the temperature difference between before and after the base sheet is brought into contact with the conveyance support member, focusing on the fact that the cause of wrinkles is the thermal expansion after the base sheet comes into contact with the can roll or the like. It is an object of the present invention to provide a film forming apparatus and a film forming method capable of suppressing the generation of wrinkles.

  The film forming apparatus of the present invention includes a heating device that heats the base sheet in a region before the base sheet contacts a conveyance support member such as a can roll.

  As a result, since the base sheet is heated and thermally expanded and then comes into contact with the transport support member, the thermal expansion when heated by gas particles or the like on the transport support member is reduced, and the heat on the transport support member is reduced. The generation of wrinkles due to expansion can be suppressed.

  Since the film forming apparatus of the present invention has the following limitations, additional effects can be obtained.

  The temperature before and after the base sheet comes into contact with the transport support member because the heating temperature of the base sheet by the heating device is within the range of the temperature of the base sheet at the portion in contact with the transport support member ± 10 ° C. Generation | occurrence | production of the wrinkle of a base material sheet can be reliably suppressed because a difference becomes small.

  Since the heating region of the base sheet by the heating device includes the contact region of the base sheet with the conveyance support member, the temperature of the base sheet can be maintained as high as possible until gas particles are deposited.

  An adhesion preventing plate is provided between the gas particle generating unit and the conveyance support member, and the heating device is installed on the side facing the gas particle generating unit with the adhesion preventing plate interposed therebetween. Generation | occurrence | production of the wrinkle of a base material sheet can be suppressed, restrict | limiting the accumulation area | region of the gas particle from a production | generation part.

  The l film-forming method of the present invention is a method in which a base sheet on which gas particles are deposited is continuously supplied onto a transport support member while applying tension, and the base sheet is heated before contacting the transport support member. And by this method, the above-mentioned effect can be produced and generation of wrinkles of the base sheet can be suppressed.

  According to the film forming apparatus or the film forming method of the present invention, it is possible to suppress the generation of wrinkles on the base material sheet on which the inorganic material is deposited.

(Embodiment)
FIG. 1 is a side view schematically showing a main part in a film forming apparatus 10 according to an embodiment of the present invention. As shown in the figure, the film forming apparatus 10 according to the present embodiment includes a vacuum chamber 11, a gas particle generation unit 13 having a tungsten boat attached to the floor of the vacuum chamber 11, and the chamber 11. And a vacuum pump 21 connected to the vacuum chamber 11 by an exhaust pipe 22. The gas particle generating unit 13 and the film forming unit 14 are partitioned by an adhesion preventing plate 36. The gas particles generated by the gas particle generating unit 13 by the deposition preventing plate 36 (in this embodiment, Si The passage range of the alloy vapor) to the film forming section 14 is limited. That is, in this Embodiment, the case where it forms into a film on the base material sheet 31 by the vacuum evaporation method is taken as an example. However, the present invention is not necessarily limited to the vacuum evaporation method, and can be generally applied to a film forming technique in which gas particles are generated at a high temperature and deposited on a base sheet.

  Although not shown in detail, the gas particle generator 13 is provided with an Si alloy ingot heated by a known resistance heating mechanism. In the present embodiment, the Si alloy film 35 used as the negative electrode material of the lithium ion secondary battery is formed on the base sheet 31 that is a copper foil. The thickness of the base sheet 31 is about 0.01 to 0.03 mm, and the thickness of the Si alloy film 35 is about 3 to 10 μm. The substrate sheet 31 is a conductor sheet such as a copper foil or an ITO film when used in a lithium ion battery, but is not necessarily limited to a conductor sheet depending on the type of film to be deposited. The composition of the Si alloy is that Si is 75 wt%, and any one of Fe, Ni, and Co, or the total of these is 25 wt%.

  The film forming unit 14 includes a sheet supply roll 32 around which the base sheet 31 is wound, a can roll 33 that is a transport support member that movably supports the base sheet 31 fed from the sheet supply roll 32, and a film forming unit 14. A winding roll 34 for winding the filmed base sheet 31 is disposed. Although not shown, the axes of the rolls 32, 33, and 34 are fixed to the ceiling surface of the vacuum chamber 11. Although not shown, the can roll 33 is cooled by cooling water passing through the inside. In this example, tension is applied to the base material sheet 31 by the braking force of the supply roll 32 and the rotational driving force of the take-up roll 34. The can roll 33 is not a crown shape but a substantially right cylindrical shape. However, a crown shape may be used within a range in which a large stress concentration does not occur, for example, only a portion extremely close to the end portion of the can roll 33 is reduced in diameter.

  The deposition preventing plate 36 has an opening formed in a region located below the can roll 33. Although the vapor | steam of Si alloy produced | generated in the gas particle production | generation part 13 is scattered in a wide range, only the gas particle which passed the opening reaches | attains the base material sheet 31. FIG. Therefore, gas particles are deposited on the continuously fed base sheet 31 while it is located within the deposition region Rdp shown by the broken line hatching in FIG.

  The base material sheet 31 is made of copper or a copper alloy serving as a negative electrode base material for a lithium secondary battery. In the deposition region Rdp, Si alloy vapor adheres to the lower surface of the base sheet 31 and solidifies and deposits to form a Si alloy film 35 that becomes a negative electrode material of the lithium ion secondary battery. In principle, the deposition region Rdp is limited to the region where the base sheet 31 is in contact with the can roll 33. This is because when the film is formed in the region where the base sheet 31 is not in contact with the can roll 33, the variation in the thickness of the film may increase or wrinkles may occur.

  Moreover, in this Embodiment, the lamp heater 40 for heating the base material sheet 31 is provided. The lamp heater 40 is arranged on the side facing the gas particle generating unit 13 with the deposition preventing plate 36 interposed therebetween, that is, on the film forming unit 14. And the base material sheet 31 sent continuously is heated by the radiation from the lamp heater 40 in the heating area | region Rht shown by the broken-line hatching of FIG. In the present embodiment, the heating region Rht always includes a region before the base sheet 31 first contacts the can roll 33 (point P1). In the present embodiment, the heating region Rht further exceeds the point P1. The contact area with the can roll 33 is included.

  According to the present embodiment, the base sheet 31 that is continuously fed by the lamp heater 40 is heated in the region before contacting the can roll 33, so that the base sheet 31 is preheated and heated. It contacts the can roll 33 while expanding. Therefore, in the deposition region Rdp, even if the base sheet 31 is heated by the resistance heating mechanism of the gas particle generation unit 13 or gas particles (Si alloy vapor in the present embodiment), the base sheet 31 contacts the can roll 33. In the meantime, since the large thermal expansion does not occur, the generation of wrinkles due to the thermal expansion of the base sheet 31 can be suppressed.

  In the present embodiment, the heating temperature by the lamp heater 40 is set in the range of the temperature ± 50 ° C. of the base sheet 31 in the deposition region Rdp. For example, the temperature in the deposition region Rdp is about 350 ° C., and the set value of the preheating temperature is about 300 ° C. Thereby, since the temperature difference between the temperature in the deposition region Rdp and the preheating temperature can be reduced, the generation of wrinkles can be reliably suppressed. However, if the heating temperature by the lamp heater 40 is in the range of the temperature of the base sheet 31 in the deposition region Rdp ± 100 ° C., the generation of wrinkles is suppressed depending on conditions such as the feed speed and tension of the base sheet. be able to.

  In particular, in the present embodiment, since the heating region Rht includes a region ahead of the point P1 where the base sheet 31 contacts the can roll 33, the temperature rise of the base sheet 31 due to preheating can be more reliably sustained. There are advantages.

  FIG. 2 shows the waveness (μm) which is the undulation of the surface of the example sample in which the Si alloy film 35 is formed on the base sheet 31 while preheating the base sheet with a heater. The dotted line position in the figure is the position at which the reference value of the webiness is determined. This data was measured with a surface roughness meter (trade name DETEK). The large dent present in the figure is an error when fixing the sample during measurement, and does not indicate waving. That is, in the sample of the embodiment, the webiness can be suppressed within 5 μm.

  FIG. 3 shows the surface waveness (μm) of the comparative example sample in which the Si alloy film 35 is deposited on the base sheet 31 without preheating with a heater. As shown in FIG. 3, it can be seen that the comparative example sample that is not preheated by the heater cannot suppress the webiness resulting from the plastic deformation of the wrinkles, and the webiness reaches about 40 μm. In other measurement results, there are cases where the webiness reaches about 200 μm.

(Other embodiments)
In the above embodiment, the can roll 33 has a substantially cylindrical shape. However, the can roll may be crowned within a range in which a large stress concentration does not occur, for example, only a portion extremely close to the end of the can roll has a small diameter. . However, in order to suppress variations in the film thickness of the film formed on the base sheet 31, the can roll 33 is preferably substantially in the shape of a right cylinder.

  Moreover, it may replace with the can roll 33, and may provide the feed support mechanism which supports a base material sheet | seat so that it can move using a slide, such as a fixed roll, without rotating. Also in that case, generation of wrinkles of the base sheet can be suppressed by preheating the base sheet with a heater before the base sheet comes into contact with the transport support member.

  In the above embodiment, the function of applying tension to the base sheet 31 is obtained by the braking force of the supply roll 32 and the rotational driving force of the take-up roll 34. A pair of pinch rolls that sandwich the base sheet from both sides may be provided on both or any one of the above. In that case, the roll on the side where the pinch roll is provided in the supply roll 31 or the take-up roll 34 is not necessarily required. This is because the base sheet may be simply folded.

  In the embodiment described above, the lamp heater 40 is used as a heating device for heating the base sheet. However, instead of the lamp heater 40, a heating device using another method such as a laser heating device or an induction heating device may be used.

  The structure of the embodiment of the present invention disclosed above is merely an example, and the scope of the present invention is not limited to the scope of these descriptions. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The film forming apparatus of the present invention can be used for forming a Si alloy film or the like used for a lithium secondary battery or the like.

It is a side view which shows a part of principal part of the film-forming apparatus in embodiment of this invention by sectional structure. It is a figure which shows the webiness of the surface of the Example sample which formed the Si alloy film on the base material sheet, preheating a base material sheet. It is a figure which shows the webiness of the surface of the comparative example sample which deposited Si alloy film on the base material sheet, without performing preheating.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film-forming apparatus 11 Vacuum chamber 13 Gas particle production | generation part 14 Film-forming part 31 Base sheet 32 Supply roll 33 Can roll 34 Winding roll 35 Si alloy film 36 Depositing plate 40 Lamp heater Rdp Deposition area Rht Heating area

Claims (5)

A gas particle generation unit for generating gas particles of an inorganic material;
A supply unit for continuously supplying a base sheet for depositing the gas particles;
A transport support member provided opposite to the gas particle generation unit and movably supporting the base sheet supplied from the supply unit;
A storage section for storing the base material sheet on which the gas particles are deposited;
A heating device that heats the base sheet at least in a region before the base sheet contacts the transport support member;
A film forming apparatus comprising: The film forming apparatus according to claim 1,
The film forming apparatus, wherein the heating temperature of the base sheet by the heating device is in the range of the temperature of the base sheet at a portion in contact with the transport support member ± 10 ° C. In the film-forming apparatus of Claim 1 or 2,
The heating region of the base sheet by the heating device includes a contact region of the base sheet with the transport support member. In the film-forming apparatus in any one of Claims 1-3,
Further comprising a deposition plate provided between the gas particle generation unit and the transport support member, and having an opening in a region facing the gas particle generation unit of the transport support member;
The said heating apparatus is a film-forming apparatus installed in the side facing the said gas particle production | generation part on both sides of the said adhesion prevention board. A process of continuously supplying a base material sheet on which gas particles of an inorganic material are deposited on a conveyance support member while applying tension;
Heating the base sheet before the base sheet contacts the transport support member; and
A film forming method including:

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