JP2014049205A - Method of manufacturing thin film lithium secondary battery, mask, apparatus of manufacturing thin film lithium secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for preventing precipitation of a dendrite metal between a mask and a base metal layer, when forming a layer composed of a material having insulation properties and lithium ion conductivity on a substrate in the vacuum by sputtering through a mask.SOLUTION: A method of manufacturing a thin film lithium secondary battery having a solid electrolyte layer 23, composed of a material having insulation properties and lithium ion conductivity, on a substrate 9 is provided. When forming a solid electrolyte layer 23 on the substrate 9 in the vacuum by sputtering through the patterning aperture 12 of a mask 10, a gap forming recess 15 is provided in the deposition side surface 14 of the mask 10, so that a portion of the deposition side surface 14 of the mask 10 contiguous to the patterning aperture 12 does not come into contact with a positive electrode collector layer 21.

Description

  The present invention mainly relates to a technique for manufacturing a lithium secondary battery using a material having both insulating properties and lithium ion conductivity, such as a solid electrolyte, and particularly to a technique for manufacturing a lithium secondary battery by a thin film in a vacuum.

  Conventionally, lithium ion secondary batteries have been widely known as power sources for mobile phones and personal computers. However, since lithium ion secondary batteries use liquid electrolytes, liquid leakage or ignition may occur. There are safety issues.

Therefore, in recent years, an all-solid-state lithium secondary battery using a solid material as an electrolyte material has been proposed, and the development thereof is progressing (for example, see Patent Document 1).
In particular, as an all-solid-state lithium secondary battery using a solid material, an all-solid-type lithium secondary battery including a thin film is expected as a power source for a card-type electronic component or the like.

Such an all-solid-state thin film lithium secondary battery is known, for example, using Li ₃ PO ₄ as a target and forming a solid electrolyte layer made of LiPON on the positive electrode layer on the substrate by sputtering. Such a conventional technique has a problem in that a dendrite-like metal is deposited between the mask and the base metal layer when the pattern is formed using the mask.

JP 2007-12324 A

  The present invention has been made in view of the problems of the prior art as described above. The object of the present invention is to provide an insulating material such as a solid electrolyte and lithium as a main material by sputtering through a mask in a vacuum. An object of the present invention is to provide a technique for preventing dendrite-like metal from being deposited between a mask and an underlying metal layer when a layer made of a material having ion conductivity is formed.

  As a result of diligent efforts to solve the above-mentioned problems, the inventor formed a layer having both insulating properties and lithium ion conductivity on a substrate by sputtering through a mask in a vacuum. It has been found that by providing a gap so that the metal portion adjacent to the opening for pattern formation does not contact the base metal layer, it is possible to prevent the dendritic metal from being deposited between the mask and the base metal layer. It came to completion.

The present invention based on such knowledge is a method for producing a thin film lithium secondary battery having a positive electrode current collecting layer, a positive electrode layer, a solid electrolyte layer, a negative electrode current collecting layer, and a negative electrode layer on a substrate, Sputtering through a mask pattern forming opening in a vacuum having a step of forming a layer having both insulating properties and lithium ion conductivity on the positive electrode current collecting layer or the negative electrode current collecting layer which is a base metal layer When forming a layer having both insulating properties and lithium ion conductivity on the substrate, the metal portion adjacent to the opening for pattern formation on the side surface of the mask forming film is not in contact with the base metal layer. It is a thin film lithium secondary battery manufacturing method including a step of forming a film by providing a gap between a metal portion and the base metal layer.
In the present invention, it is also effective when the layer having both insulating properties and lithium ion conductivity is one or more layers selected from the group consisting of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer. is there.
The present invention is also effective when the solid electrolyte layer is made of a lithium phosphate oxynitride glass electrolyte.
The present invention provides a mask for carrying out any one of the above-described methods for manufacturing a thin film lithium secondary battery, wherein a predetermined depth is formed in a metal portion adjacent to the pattern forming opening on a film formation side surface of the mask. The gap forming recess is provided.
The present invention is a thin-film lithium secondary battery manufacturing apparatus that includes a vacuum chamber for sputtering and is configured so that the above-described mask is disposed close to a substrate in the vacuum chamber.

The present invention has the following effects.
That is, in the prior art, when forming a layer having both insulating properties and lithium ion conductivity, such as a solid electrolyte layer, a positive electrode layer, or a negative electrode layer, on a substrate by sputtering using a mask having a metal part, the underlying metal layer When the mask is mounted on the positive electrode or negative electrode current collecting layer, the metal portion of the mask contacts the base metal layer and is connected in a circuit.

  When a layer having both insulating properties and lithium ion conductivity is formed on the base metal layer, a closed circuit is formed by the mask, the base metal layer, and the layer having both insulating properties and lithium ion conductivity. An electric field generated in a layer having both insulating properties and lithium ion conductivity causes a bias of lithium ions, and dendritic metal deposition occurs due to ion migration.

  On the other hand, in the present invention, the gap is formed by, for example, a gap-forming recess so that the metal portion adjacent to the pattern-forming opening on the film-forming side surface of the mask does not come into contact with the positive electrode or the negative electrode current collecting layer as the base metal layer. By forming a layer having both insulating properties and lithium ion conductivity, such as a solid electrolyte layer and a positive electrode layer or a negative electrode layer, on a substrate by sputtering through a mask pattern formation opening in a vacuum, Since the contact between the metal part of the mask and the underlying metal layer can be prevented, when a layer having both insulating properties and lithium ion conductivity is formed on the underlying metal layer, the mask, the underlying metal layer, the insulating property and the lithium ion It is possible to prevent the formation of a closed circuit due to the layer having conductivity.

Accordingly, it is possible to prevent the dendritic metal from being deposited between the mask and the base metal layer, so that a short circuit between the negative electrode and the positive electrode can be suppressed, and the yield in the manufacturing process can be improved.
In addition, according to the present invention, deterioration of film quality caused by dendritic metal deposits can be prevented, so that long-term reliability of the battery can be improved.

Sectional drawing which shows the internal structure of the lithium secondary battery manufacturing apparatus of embodiment of this invention (A) (b): Plan views showing the mask of the present embodiment Sectional drawing which shows the structural example of the thin film lithium secondary battery created by this invention The top view which shows the magnitude relationship of the positive electrode current collection layer in this Embodiment, a positive electrode layer, and a solid electrolyte layer (A): Plan view showing a pattern forming opening and a gap forming recess in the mask of the present embodiment (b): AA line sectional view of FIG. 6A and 6B are explanatory diagrams of the principle of the present embodiment, in which FIG. 6A illustrates the prior art, and FIG. 6B illustrates the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing the internal configuration of the lithium secondary battery manufacturing apparatus of the present embodiment.
As shown in FIG. 1, the lithium secondary battery manufacturing apparatus 1 of the present embodiment includes a vacuum chamber 3 connected to a vacuum exhaust system 2 having, for example, a turbo molecular pump and a dry pump. The vacuum chamber 3 is configured such that a sputtering gas such as nitrogen gas is introduced through a gas introduction source 4.

In the vacuum chamber 3, a cathode electrode 6 that is integrally formed and has a sputtering target 5 is provided.
The cathode electrode 6 is connected to a high frequency power source 7 provided outside the vacuum chamber 3, and is configured to apply a high frequency power of, for example, 13.56 Mhz to the sputtering target 5.

A stage 8 is provided at a position facing the sputtering target 5 in the vacuum chamber 3, a substrate 9 is disposed on the stage 8, and a mask 10 to be described later is disposed on the substrate 9. It has become.
In the case of the present embodiment, the substrate 9 is arranged to have a floating potential.

2A and 2B are plan views showing the mask of the present embodiment. FIG. 2A shows the target side surface, and FIG. 2B shows the film formation side surface.
As shown in FIGS. 2A and 2B, the mask 10 of the present embodiment has a flat mask body 11 made of metal, for example, and a plurality of pattern forming openings 12 in the mask body 11. Is provided.

  In the present embodiment, a gap forming concave portion 15 to be described later is provided in the vicinity of each pattern forming opening 12 on the film forming side surface 14 which is the surface opposite to the target side surface 13 of the mask main body 11. Yes.

FIG. 3 is a cross-sectional view showing a structural example of a thin film lithium secondary battery produced by the present invention.
As shown in FIG. 3, a thin film lithium secondary battery 20 produced according to the present invention includes a positive electrode current collecting layer 21, a positive electrode layer 22, a solid electrolyte layer 23, a negative electrode current collecting layer 24, a negative electrode on the substrate 9 described above. The layer 25 and the sealing layer 26 are sequentially formed.

The substrate 9 is made of, for example, glass, and is formed in, for example, a rectangular shape.
When a glass substrate is used as the substrate 9, it is preferable because reactivity with each layer formed on the substrate 9 is low.

The positive electrode current collecting layer 21 that is a base metal layer is formed of a metal such as a platinum / titanium (Pt / Ti) alloy, for example, and is configured such that the end 21a on the connection terminal side is exposed.
The positive electrode current collecting layer 21 can be formed by DC sputtering using, for example, a target made of platinum and a target made of titanium.

The positive electrode layer 22 is made of, for example, lithium cobalt oxide (LiCoO ₂ ).
The positive electrode layer 22 can be formed by RF sputtering using a sputtering target made of lithium cobalt oxide.

The solid electrolyte layer 23 which is a layer having both insulating properties and lithium ion conductivity is formed of, for example, a lithium phosphate oxynitride glass electrolyte (LIPON).
The solid electrolyte layer 23 can be formed by RF sputtering using a sputtering target made of lithium phosphate (Li ₃ PO ₄ ).

The negative electrode current collecting layer 24 that is a base metal layer is formed of a metal such as a nickel / chromium (Ni / Cr) alloy.
The negative electrode current collecting layer 24 can be formed by DC sputtering using a target made of nickel and a target made of chromium, for example.

The negative electrode layer 25 is made of, for example, metallic lithium (Li).
The negative electrode layer 25 can be formed by vacuum deposition using metallic lithium as an evaporation source.

The sealing layer 26 is formed, for example, by laminating an alumina (Al ₂ O ₃ ) layer 27 and a polyurea layer 28.
Here, the alumina layer 27 can be formed by RF sputtering using a target made of aluminum (Al) in an oxygen (O ₂ ) gas atmosphere, for example.

On the other hand, the polyurea layer 28 can be formed, for example, by vapor deposition polymerization.
In this case, as a raw material monomer for vapor deposition polymerization, for example, 1,12-diaminododecane can be suitably used as a diamine monomer, and for example, 1,3-bis (isocyanatomethyl) cyclohexane can be suitably used as an acid component monomer.

FIG. 4 is a plan view showing the magnitude relationship among the positive electrode current collecting layer, the positive electrode layer, and the solid electrolyte layer in the present embodiment.
As shown in FIG. 4, in the present embodiment, the length in the longitudinal direction is smaller than that of the positive electrode current collector layer 21 at the portion opposite to the connection terminal side end 21 a of the rectangular positive electrode current collector layer 21. A positive electrode layer 22 is formed, and a solid electrolyte layer 23 is further formed so as to cover the entire surface of the positive electrode layer 22.

  In such a configuration, when the solid electrolyte layer 23 is formed using the mask 10 described above, the region outside the pattern forming opening 12 of the mask body 11, that is, the connection terminal side of the positive electrode current collecting layer 21. The exposed region 21b of the mask 10 faces the film formation side surface 14 of the mask 10.

When the exposed region 21 b of the positive electrode current collecting layer 21 comes into contact with the mask 10 during film formation, a dendritic metal is deposited between the mask 10 and the positive electrode current collecting layer 21.
Therefore, in the present embodiment, the mask 10 is provided with the following means.

FIG. 5A is a plan view showing a pattern forming opening and a gap forming recess in the mask of the present embodiment, and FIG. 5B is a cross-sectional view taken along line AA of FIG. 5A. .
As shown in FIGS. 5A and 5B, in the mask 10 of the present embodiment, the pattern is formed on the side surface 14 of the mask body 11 so as to correspond to the exposed region 21b of the positive electrode current collecting layer 21 described above. A gap forming recess 15 having a predetermined depth is provided in a portion adjacent to the forming opening 12, that is, a portion corresponding to the exposed region 21 b on the connection terminal side of the positive electrode current collecting layer 21.

  In this case, the depth of the gap forming recess 15 provided in the mask 10 is not particularly limited. However, when the depth exceeds a predetermined value, the cathode current collecting layer 21 is caused by the wraparound of sputtered particles during film formation. May be covered with an insulating film and the resistance value may increase.

Therefore, in the case of the present invention, from the viewpoint of preventing the exposed region 21b of the positive electrode current collecting layer 21 from coming into contact with the mask 10 and preventing spattering of sputtered particles during film formation, The depth (the distance d between the film-forming side surface 14 of the mask 10 and the bottom surface of the gap forming recess 15 shown in FIG. 5B) is configured to be greater than the thickness of the solid electrolyte layer 23 and 1 mm or less. It is more preferable.
In addition, the solid electrolyte layer 23 in this invention is formed in the range of 1-10 micrometers.

  In the case of the present invention, the distance between the edge of the gap forming recess 15 of the mask 10 and the edge of the exposed region 21b of the positive electrode current collecting layer 21 (distance p shown in FIG. 5A) is particularly limited. However, it is more preferably set to 0.1 to 30 mm from the viewpoint of reliably preventing the precipitation of dendritic metal during film formation.

  In the present embodiment having such a configuration, when the solid electrolyte layer 23 is formed on the substrate 9, the positive electrode current collecting layer 21 and the positive electrode layer 22 are formed in advance using the sputtering apparatus shown in FIG. 1. The placed substrate 9 is placed on the stage 8 in the vacuum chamber 3, and the above-described mask 10 is attached to the substrate 9.

Then, the vacuum evacuation system 2 is operated to bring the pressure in the vacuum chamber 3 into an ultra-high vacuum state, nitrogen gas is introduced into the vacuum chamber 3 and magnetron sputtering is performed (for example, pressure 0.3 Pa, power 2 kW), and the substrate A solid electrolyte layer 23 (LiPON film) having both insulating properties and lithium ion conductivity is formed on the substrate 9.
Thereafter, the negative electrode current collecting layer 24, the negative electrode layer 25, and the sealing layer 26 described above are formed on the solid electrolyte layer 23, whereby the target thin film lithium secondary battery 20 is obtained.

The above-described embodiment has the following effects.
That is, in the case of the prior art, as shown in FIG. 6A, when forming the solid electrolyte layer 23 having both insulating properties and lithium ion conductivity on the substrate 9 by sputtering using the mask 10 made of metal, the base metal By mounting the mask 10 on the positive electrode current collecting layer 21, which is a layer, the film formation side surface 14 of the mask 10 comes into contact with the connection terminal side end 21 a of the positive electrode current collecting layer 21 and is connected in circuit.

  When the solid electrolyte layer 23 is formed on the positive electrode current collecting layer 21, a closed circuit is formed by the mask 10, the positive electrode current collecting layer 21, and the solid electrolyte layer 23, and as a result, the solid electrolyte layer 23 is generated. Lithium ions are biased by the electric field, and dendritic metal 30 is deposited by ion migration at the interface between the solid electrolyte layer 23 and the mask 10.

  In contrast, in the present embodiment, as shown in FIG. 6B, the positive electrode current collecting layer in which the portion adjacent to the pattern forming opening 12 on the film formation side surface 14 side of the mask 10 is a base metal layer By providing the gap forming recess 15 so as not to come into contact with 21, the solid electrolyte layer 23 having both insulating properties and lithium ion conductivity on the substrate 9 by sputtering through the pattern forming opening 12 of the mask 10 in vacuum. Since the contact between the mask 10 and the end portion 21a on the connection terminal side of the positive current collecting layer 21 can be prevented, the mask is formed when the solid electrolyte layer 23 is formed on the positive current collecting layer 21. 10, the positive electrode current collecting layer 21 and the solid electrolyte layer 23 can be prevented from forming a closed circuit.

  As a result, it is possible to prevent the dendrite-like metal 30 from being deposited between the mask 10 and the positive electrode current collecting layer 21, so that a short circuit between the negative electrode and the positive electrode can be suppressed, and the yield in the manufacturing process can be improved. Since deterioration of film quality caused by dendritic metal deposits can be prevented, long-term reliability of the battery can be improved.

The present invention is not limited to the above-described embodiment, and various changes can be made.
For example, in the above-described embodiment, the case of a solid electrolyte made of lithium phosphate oxynitride glass electrolyte (LIPON) is described as an example of the material of the layer having both insulating properties and lithium ion conductivity. Without limitation, all solid electrolytes containing lithium (for example, Li ₂ O—B ₂ O ₅ + N, Li ₂ S—P ₂ S ₅ , Li ₂ S—SiS and other glass-based solid electrolytes, Li ₂ Ti ₃ O ₇ , Li ₃ N, La _0.5 Li _0.5 TiO _3, etc., and materials having both insulating properties and lithium ion conductivity, such as a positive electrode layer made of lithium iron phosphate (LiFePO ₄ ) or lithium titanate It can be applied when forming a negative electrode layer made of (Li ₄ Ti ₅ O ₁₂ ).

  In the above-described embodiment, the case where the mask is made of a metal material has been described as an example. However, the present invention is not limited to this, and the present invention is also applicable to a mask made of, for example, ceramics and having a metal portion on a film formation side surface. be able to.

  That is, in the prior art, there are problems such as dendrite-like metal precipitation between the metal that fixes the mask made of ceramics and, for example, the solid electrolyte layer, generating particles and increasing the stress of the film. According to the present invention, such a problem can be solved.

  Furthermore, in the above-described embodiment, a gap forming recess is provided on the mask film forming side surface so that the metal portion adjacent to the pattern forming opening on the film forming side surface of the mask has both insulating properties and lithium ion conductivity. However, the present invention is not limited to this. For example, by providing a protrusion-like spacer on the mask, the metal portion adjacent to the pattern forming opening on the side surface of the mask forming film can be provided. It is also possible to configure so as not to contact a layer having both insulating properties and lithium ion conductivity.

DESCRIPTION OF SYMBOLS 1 ... Lithium secondary battery manufacturing apparatus 3 ... Vacuum chamber 9 ... Substrate 10 ... Mask 11 ... Mask main body 12 ... Pattern formation opening 14 ... Film-forming side surface 15 ... Gap formation recessed part 20 ... Thin film lithium secondary battery 21 ... Positive electrode Current collecting layer 22 ... Positive electrode layer 23 ... Solid electrolyte layer 24 ... Negative electrode current collecting layer 25 ... Negative electrode layer 26 ... Sealing layer

Claims (5)

A method for producing a thin film lithium secondary battery having a positive electrode current collecting layer, a positive electrode layer, a solid electrolyte layer, a negative electrode current collecting layer, and a negative electrode layer on a substrate,
Forming a layer having both insulating properties and lithium ion conductivity on the positive electrode current collecting layer or the negative electrode current collecting layer which is a base metal layer on the substrate;
When forming a layer having both insulation and lithium ion conductivity on the substrate by sputtering through a mask pattern formation opening in a vacuum, adjacent to the pattern formation opening on the side of the film formation of the mask A method for producing a thin film lithium secondary battery, comprising: forming a film by providing a gap between the metal part and the base metal layer so that the metal part to be touched does not contact the base metal layer.   2. The thin film lithium secondary battery according to claim 1, wherein the layer having both insulating properties and lithium ion conductivity is one or more layers selected from the group consisting of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer. Production method.   The method for producing a thin film lithium secondary battery according to claim 1, wherein the solid electrolyte layer is made of a lithium phosphate oxynitride glass electrolyte. A mask for carrying out the method for producing a thin film lithium secondary battery according to claim 1,
A mask in which a gap forming recess having a predetermined depth is provided in a metal portion adjacent to the pattern forming opening on the film forming side surface of the mask.   An apparatus for manufacturing a thin film lithium secondary battery, comprising: a vacuum chamber for sputtering, wherein the mask according to claim 4 is arranged close to the substrate in the vacuum chamber.

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