JPH03200309A - Laminated thin-film dielectric element and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable forming the title dielectric element according to a thin film thickness by forming double electrode films having SnO2 thin film on the surface and Cr, Ni or Cu thin film on the rear surface and further TiO2 dielectric thin films through causing these films to make an epitaxial growth respectively by means of vapor deposition and by laminating these two sorts of films alternately. CONSTITUTION:The title dielectric element has a fundamental structure, in which double electrode films 2, 3 which the thickness of 10mum and less having SnO2 thin film 3 on the front and Cr, Ni or Cu thin film 2 on the rear and TiO2 dielectric films 4 with the thickness of 10mum and less are alternately laminated on a glass substrate 1. In this case, a part or the whole of plural SnO2/(Cr, Ni or Cu) double electrode films 2, 3, 5, 7 and 9, as internal electrode layers for obtaining capacity, is composed of at least two groups connected with lead-out ends differing from each other. Thus, a low-cost glass substrate 1 is used so that internal electrode thin films can alternately be laminated on the glass substrate according to a thin thickness while holding dielectric thin films 4, 6 and 8 between them.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film dielectric element having a laminated structure and a method for manufacturing the same.

[Conventional technology] Conventionally, ceramic multilayer capacitors have been widely used as dielectric elements with small size and large capacity.In chip-type multilayer capacitors without lead wires, capacitance is obtained by sandwiching thin dielectric ceramic layers. Internal electrode layers are alternately stacked to face each other, and the terminal ends of the internal electrodes are connected to external terminal electrodes that can be directly soldered.

In order to increase the acquisition capacity of the element in this multilayer capacitor, attempts are usually made to reduce the thickness of each dielectric layer. However, in the case of multilayer ceramic capacitors, in order to realize a ceramic dielectric layer with a thickness of 101t1a or less, there are many steps such as creating a thin green sheet, sheet attack of electrode paste, pressure molding, and controlling the particle size of dielectric particles after firing. Due to difficult technical issues, the current dielectric layer thickness is 511! Ceramic multilayer capacitors with a diameter of less than m have not been announced.

On the other hand, using vapor deposition techniques such as vapor deposition and sputtering,
Attempts have been made to fabricate thin film capacitors with high capacitance, but thin films based on ferroelectric materials such as barium titanate and lead-based perovskite, which can be expected to obtain high capacitance, have a crystalline phase when passing the Curie point. Good quality dielectric thin films have not been obtained due to the problem of distortion caused by dislocation. In addition, in order to avoid the problem of distortion that occurs during this crystal phase transition, there is a method of epitaxial growth from a base substrate, but the base substrate is made of an expensive single crystal (for example, SrTiO3, PT, etc.).
Since it is limited to , there is no prospect of practical application.

[Problems to be Solved by the Invention] As mentioned above, despite various studies being conducted to meet the demand for further miniaturization of multilayer ceramic capacitors, products with a dielectric film thickness of less than 5 mm have been developed. has not been put into practical use, and even thin film capacitors using vapor deposition have the drawbacks mentioned above. Therefore, there has been no technology for simply laminating high-quality dielectric films at a thickness of less than 10 m, preferably less than 5 m, at low cost.

An object of the present invention is to provide a multilayer thin film dielectric element formed of a dielectric thin film having a thickness of less than 10 μm, preferably less than 5 μm, without using an expensive single crystal substrate.

[Means and effects for solving the problem] In order to achieve the above object, the inventors of the present invention have conducted research using an inexpensive glass substrate, and deposited a thin film of SnO2 on the surface and a Cr5Ni or Cr5Ni film on the back surface using an evaporation method. A double electrode film (hereinafter abbreviated as 5nOz/(Cr, Ni or Cu) double electrode film) having a Cu thin film was formed by epitaxially growing a TiO2 dielectric thin film, and these two types of films were It has been discovered that by alternately laminating layers, it is possible to obtain a laminated thin film dielectric element having a structure similar to that of a conventional laminated ceramic capacitor, and having a film thickness preferably thinner than 5 LOss, but even about 1 LOuss. We have arrived at the present invention.

That is, the present invention first provides a laminated thin film dielectric element as described below.

On the glass substrate, SnO2 thin film on the front surface, Cr and N on the back surface.
A basic structure in which dual electrode films with a thickness of 1 or less, preferably 5 or less, and a TiO2 dielectric film with a thickness of 10 or less, preferably 5 or less, having a thin Cu or Cu thin film are laminated alternately. and some or all of the plurality of SnO2/(CrSNi or Cu) double electrode films are composed of at least two groups connected to mutually different lead-out ends as internal electrode layers for obtaining capacitance. A multilayer thin film dielectric element characterized by:

Second, the present invention provides a method of manufacturing a laminated thin film dielectric element as described below.

(a) A glass substrate with a thickness of 1OI11n or less, preferably 57ZII+, having a predetermined shape and area by CVD method.
The following SnO2/ (Cr, Ni or Cu) double electrode film (SnO2 thin film on the surface, Cr5Ni or Cu on the back side)
A first SnO2/(C
(r, Ni or Cu) dual electrode film (r) (r) Double electrode film (D); to form a TiO□ dielectric film with a thickness of 10 μm or less, preferably 5 μm or less, and remove unnecessary portions by dry etching to form a first TiO2 film (1); (c) the above TiO2 film; (CV on top of D
Epitaxially grown using the D method to a thickness of lOZ/ff
S n 02 / (
CrSN i or Cu) double electrode film is formed, unnecessary portions are removed by wet etching, and the second Sn
02/(Cr.

Ni or Cu) double electrode film (■); (d) above S
n 02 / (Cr, Ni or Cu) double electrode film (
A second TiO2 film is formed on the substrate in the same manner as in (b), and all or a part of the above (a) to (d) are repeated to form the following dielectric element, that is, a glass substrate. above,
SnO2 thin film on the front surface, Cr on the back surface.

A double electrode film with a thickness of 10W or less, preferably 5uItl or less, with a Ni or Cu thin film and a thickness of 101! It has a basic structure in which TiO2 dielectric films of ja or less are laminated alternately, and the plurality of SnO2/
A laminated thin film dielectric element characterized in that part or all of the double electrode film is composed of at least two groups connected to different lead-out ends as internal electrode layers for obtaining capacitance. manufacturing method.

FIG. 1 is a schematic cross-sectional view showing the film forming order in manufacturing a laminated thin film dielectric element of the present invention. As shown in FIG. It has a structure in which a double electrode film made of Cr film and a dielectric TiO2 film are alternately laminated, and the double electrode film is drawn out as an external terminal, and has substantially the same structure as a conventional multilayer ceramic capacitor. are doing. In addition, in order to improve adhesion to the glass substrate or dielectric film, a C film is placed on the back side of the electrode film to create a double structure. It is possible to provide a laminated thin film dielectric element having a dielectric film thinner than, preferably, 5 or more.

The present invention will be further explained below with reference to Examples.

[Example 1] The order of fabrication of the laminated thin film dielectric element of the present invention will be explained according to the above-mentioned FIGS. 1(a) to 1(g).

(a) Borosilicate glass substrate (Corning #705
9) SnO2 film 3 and Cr film 2 are placed on top and bottom of 1, respectively.
to form a double film each having a thickness of 0.5 μm,
One end of this double film was removed by wet etching to obtain a 5 film 02/Cr double electrode film (1).

(b) TiO2 film 4 is applied to this double electrode film 4 by CVD method.
By epitaxial growth on the underlying SnO2 film,
A TiO2 film (1) was formed by forming a film with a thickness of 1 μm, and removing both end portions of this TiO2 film by dry etching.

(c) This TiO2 film ■ has SnO2/C as described above.
A double electrode film 5 was formed with a thickness of 0.5 mm each, and one end was removed by wet etching to obtain a double electrode film (2).

(d) Next, the TiO2 film 6 is deposited on the base layer S by the CVD method.
The nO2 film is epitaxially grown to a thickness of one layer, and both ends are removed by dry etching as shown in the figure (d) to form a TiO2 film.
The O2 film (2) is directly bonded to the TiO2 film (2) to form a shape that covers one end of the double electrode film (0).

(e) Furthermore, a TiO2 film (SnO as mentioned above)
A 2/Cr double electrode film (each film thickness 0.5IIM) 7 was formed, and one end was removed by wet etching to obtain a double electrode film G). As a result, a structure is obtained in which one end of the double electrode film (1) and the double electrode film (2) are in direct contact.

(f) Furthermore, the TiO2 film 8 is coated with SnO as an underlayer by CVD method.
Two films were formed with a thickness of IIIM by epitaxial growth, and both sides of this TiO2 film were removed by dry etching to form a TiO2 film (2). At this time, TiO2
The film O) is directly bonded to the TiO2 film (G) to form a double electrode film G.
) is shaped to cover one end of the

(g) On the laminated film obtained from the above steps, the SnO2/Cr double electrode film (each film thickness 0.5 M) as described above was applied.
was formed, and one end was removed by wet etching to form a double electrode film).

(h) By repeating the steps (a) to (g) above, T
A multilayer thin film dielectric element with substantially the same structure as a conventional multilayer ceramic capacitor is formed, in which SnO2/Cr dual electrode films are alternately connected to end electrodes with i02 dielectric films in between. be done.

By this method, the highest electrostatic capacitance can be obtained when comparing the same number of laminated layers.

[Example 2] The order of manufacturing a laminated thin film dielectric element of the present invention will be explained with reference to FIGS. 2(a) to (k).

(a) Borosilicate glass substrate (Corning #705
9) SnO2 film 3 and Cr film 2 are placed on top and bottom of 1, respectively.
A double film having a thickness of 0.5-2 was formed, and both ends of this double film were removed by wet etching to form a Sn 02 /Cr double electrode film q). .

(b) TiO□ film 4 is applied to this double electrode film ② by CVD method.
By epitaxial growth on the underlying SnO film,
A TiO 2 film (1) was formed by dry etching to remove both ends of this TiO□ film.

(c) A SnO2 film and a Cr double electrode film 5 as described above are formed on this TiO film 5 with a thickness of 0.5 mm each, and one end is removed by wet etching to form a double electrode film. (
It was.

(d) Next 1:, CV D Method 1: T i O2I
T! 6 was epitaxially grown on the underlying S n O2 film to a thickness of one layer, and both ends were removed by dry etching as shown in the figure (d) to form a TiO2 film. is directly bonded to the TiO2 film (2) and has a shape that covers one end of the double electrode film (2).

(e) Furthermore, a TiO2 film (SnO2/
A Cr double electrode film (each film thickness: 0.5 nm) 7 was formed, and one end portion was removed by wet etching to obtain a double electrode film (2).

(f) Furthermore, the TiO2 film 8 is coated with SnO as an underlayer by CVD method.
A TiO2 film was formed with a thickness of one layer by epitaxial growth, and both sides of this TiO2 film were removed by dry etching to obtain a TiO2 film. At this time, TiO
The two films ■ are the TiO2 films (which are directly bonded to the double electrode films ■
It has a shape that covers one end of the.

(g) On the laminated film obtained from the above steps, the SnO2/Cr double electrode film (each film thickness 0.5 &) as described above is applied.
was formed, and one end was removed by wet etching to form a double electrode film). As a result, a structure is obtained in which the double electrode film (one end of the wire and the double electrode film) is in direct contact.

(h) CVD method Niori TiO2 film 10 is formed to a thickness of lum by epitaxial growth on the underlying SnO2 film, and both sides of this TiO2 film are removed by dry etching to form a TiO2 film. (to the membrane). At this time, the TiO □ film) is directly joined to the TiO 2 film ■, forming a shape that covers one end of the dual electrode film).

(i) On the laminated film obtained from the above steps, the SnO2/Cr double electrode film (each film thickness 0.5 nm) as described above is applied.
II was formed, and one end was removed by wet etching to obtain a double electrode film 6). As a result, the double electrode film■
The structure is such that one end of the double electrode film (1) is in direct contact with the double electrode film (2).

(j) Further+Z CVD method Niori TiO2 film 12 was formed on the base SnO2 film by epitaxial growth to a certain thickness, and both sides of this TiO□ film were removed by dry etching to form a TiO2 film ■. At this time,
The TiO2 film (2) is directly bonded to the Ti02 film (A) and has a shape that covers one end of the double electrode film (2).

Following this, (aSb), (CSd), (
All or part of the operations e, f) (or gSh) (or L j) can be repeated, but are omitted here.

(k) On the laminated film obtained from the above steps, the SnO2/Cr double electrode film (each film thickness 0.5 M) as described above was added 1
3 was formed, and both end portions were removed by wet etching to obtain a double electrode film (6). As a result, the SnO2/
The Cr double electrode film becomes a third electrode independent from the terminal electrodes on both sides.

As a result of the above, with a dielectric layer made of TiO2 film in between,
A structure in which SnO2/Cr double electrodes are alternately stacked, and all or some of the SnO2 electrodes have their ends gathered at the ends of the element, resulting in three (or more) electrodes that do not touch each other. was provided.

[Example 3.4] Steps of Example 1, (a), (c), (e), (g), (
In h), all the steps were the same as in Example 1 except that the Cr/SnO2 double electrode film was changed as shown in Table 1.

[Example 5.6] (a), (c), (e), (g), (i) of Example 2,
(k)l: The same method as in Example 1 was repeated except that the 01750022 double electrode film was changed as shown in Table 1.

Table 1 [Effects of the Invention] As explained above, according to the present invention, although the structure is similar to that of a conventional multilayer ceramic capacitor, an inexpensive glass substrate is used and a dielectric thin film is sandwiched thereon. It is possible to provide a laminated thin film dielectric element in which internal electrode thin films are alternately laminated with a thickness of less than 10 m, preferably less than 5111 m.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the sequence of film formation in an embodiment of the multilayer thin film dielectric element of the present invention. FIG. 2 is a schematic cross-sectional view showing the sequence of film formation in another embodiment of the present invention. Explanation of symbols 1... Glass substrate 7... Double electrode film (ri 8... TiO2 film (3) 9... Double electrode film) 10... TiO2 film ) 11...Double electrode film■ 12...TiO2 film■ 13...Double electrode film (6)

Claims (2)

[Claims] (1) A basic structure in which dual electrode films with a thickness of 10 μm or less and TiO_2 dielectric films with a thickness of 10 μm or less are alternately laminated on a glass substrate, with a SnO_2 thin film on the front surface and a Cr, Ni, or Cu thin film on the back surface. structure, the plurality of SnO
Part or all of the _2/(Cr, Ni or Cu) double electrode film is composed of at least two groups connected to different lead-out ends as internal electrode layers for obtaining capacitance. Characteristic multilayer thin film dielectric elements. (2) (a) SnO_2/(Cr with a thickness of 10 μm or less with a predetermined shape and area by CVD method on a glass substrate,
Ni or Cu) double electrode film (SnO_2 thin film on the surface,
(Double electrode film with Cr, Ni or Cu thin film on the back side)
and remove unnecessary portions by wet etching to form a first SnO_2/(Cr, Ni or Cu)2
As a heavy electrode film (1); (b) TiO_2 with a thickness of 10 μm or less is epitaxially grown on the SnO_2 base film by the CVD method on this SnO_2/(Cr, Ni or Cu) double electrode film (1). A dielectric film is formed and unnecessary portions are removed by dry etching to obtain a first TiO_2 film (1); (c) Epitaxial growth is performed on the TiO_2 film (1) by CVD to a thickness of 10 μm or less. SnO_2
/(Cr, Ni or Cu) double electrode film is formed, unnecessary parts are removed by wet etching, and the second S
nO_2/(Cr, Ni or Cu) double electrode film (2)
(d) The above SnO_2 / (Cr, Ni or Cu)2
A second TiO layer is placed on the heavy electrode film (2) in the same manner as in (b).
_2 Film (2) is formed on the following dielectric element, which consists of repeating all or part of the above (a) to (d), that is, on a glass substrate,
Dual electrode film with a thickness of 10 μm or less and a thin film of SnO_2 on the surface and a thin film of Cr, Ni or Cu on the back surface and a thickness of 10 μm
It has a basic structure in which TiO_2 dielectric films of less than A method for manufacturing a laminated thin film dielectric element, characterized in that the internal electrode layer comprises at least two groups connected to different lead-out ends.