WO2007023909A1

WO2007023909A1 - DIELECTRIC FILM HAVING ABOx-TYPE PEROVSKITE CRYSTALLINE STRUCTURE, CAPACITOR USING THE DIELECTRIC FILM, AND METHOD AND SYSTEM FOR FORMATION OF DIELECTRIC FILM HAVING ABOx-TYPE PEROVSKITE CRYSTALLINE STRUCTURE

Info

Publication number: WO2007023909A1
Application number: PCT/JP2006/316631
Authority: WO
Inventors: Katsuya Okumura; Kinji Yamada; Tomotaka Shinoda; Daohai Wang; Takahiro Kitano; Yoshiki Yamanishi; Muneo Harada; Tatsuzo Kawaguchi; Yoshihiro Hirota; Kenji Matsuda
Original assignee: Tokyo Electron Limited; Octec Inc.; Ibiden Co., Ltd.
Priority date: 2005-08-24
Filing date: 2006-08-24
Publication date: 2007-03-01
Also published as: JP4912081B2; JP2007088437A; TW200731466A

Abstract

Disclosed is a dielectric film (3) having an ABOx-type perovskite structure which is composed of a laminate of films each having an ABOx-type perovskite structure. The dielectric film (3) can be produced by, onto a first thin film (31) which has an ABOx-type perovskite crystalline structure and has voids (42) having an average diameter equal to or larger than a predetermined value, applying a second coating solution containing particles each of which has an ABOx-type perovskite crystalline structure and which has an average particle diameter smaller than the average diameter of the voids (42) and then heating and firing the resulting product to form a second thin film (32) having an ABOx-type perovskite crystalline structure on the first thin film (31). The dielectric film (3) is characterized in that the density at the boundary between the first thin film (31) and the second thin film (32) is higher than the density at any other area of the dielectric film (3).

Description

Specification

Dielectric film having ABOx type perovskite crystal structure, capacitor using the dielectric film, and method and system for forming dielectric film having ABOx type perovskite crystal structure

Technical field

The present invention relates to a dielectric film having an ABOx type perovskite crystal structure, a capacitor using the dielectric film, and a method and a system for forming a dielectric film having an ABOx type perovskite crystal structure.

Background art

[0002] In recent years, a technique for making the distance between a capacitor and a CPU on a board substantially zero from the viewpoint of stably supplying power to a computer CPU has been studied. A dielectric film (for example, barium titanate) having an ABOx type perovskite crystal structure has attracted attention as a dielectric film constituting the capacitor in this case.

A sol-gel method is known as a method for producing a dielectric film having this ABOx type perovskite crystal structure. However, the dielectric film obtained by the sol-gel method is characterized by low crack resistance. Specifically, cracks occur when the thickness of the dielectric film per layer to be formed exceeds lOOnm. Therefore, the film thickness per layer needs to be 100 ηm or less. However, this reduces the distance between the electrodes and increases the leakage current. As a result, the capacitor is not suitable for stable power supply.

[0004] Generally, in order to use as a dielectric film for a capacitor, the film thickness must be 300 nm or more from the viewpoint of reducing leakage current. Therefore, multilayer coating is performed, for example, to increase the thickness of the entire barium titanate thin film. However, if baking is repeated in a multi-layer coating, the barium titanate crystals in the coating film cause grain growth, increasing the surface roughness. For this reason, while the film thickness can be increased, the gap between crystal grains becomes a leakage point, and conversely, the leakage current may be increased.

Disclosure of the invention Problems to be solved by the invention

[0005] From the above, it is desired to establish a new method for forming a dielectric film having an ABOx type perovskite crystal structure capable of reducing leakage current.

Means for solving the problem

[0006] In order to solve the above problems, a dielectric film having an ABOx type perovskite crystal structure of the present invention includes a first dielectric thin film having an ABOx type perovskite crystal structure, and the first dielectric thin film. A dielectric film in which a second dielectric thin film having an ABOx-type bettobushite crystal structure is formed on the dielectric thin film, and the average particle size of the crystal particles constituting the second dielectric thin film is In the boundary region between the first dielectric thin film and the second dielectric thin film, which is smaller than the average particle diameter of crystal grains constituting the first dielectric thin film, the first dielectric thin film is The crystal grains constituting the second dielectric thin film are mixed with the crystal grains constituting the second dielectric thin film.

[0007] In the dielectric film having the ABOx type perovskite crystal structure configured as described above, a density of a boundary region between the first dielectric thin film and the second dielectric thin film is higher than that of the first dielectric thin film. It is desirable that the density of other regions and the density of the second dielectric thin film be higher.

[0008] A capacitor using a dielectric film having an ABOx type perovskite crystal structure according to the present invention is characterized in that a pair of electrodes are formed on a pair of main surfaces of the dielectric film having the above characteristics. To do.

[0009] The method for forming a dielectric film having an ABOx-type bottom bskite structure according to the present invention provides a first dielectric thin film having an ABOx-type bottom bumskite crystal structure including voids having an average diameter of a predetermined value or more. A first dielectric thin film comprising: a first dielectric thin film comprising: a step of forming a dielectric composition composition comprising: an ABOx-type perovskite crystal structure having an average particle size smaller than the average diameter of the voids; A coating process to be applied on top and a resultant product obtained by the coating process are baked to form a second dielectric thin film having an ABOx-type bobsite crystal structure on the first dielectric thin film. And a firing step.

[0010] The dielectric-forming composition liquid for forming the second dielectric thin film comprises a metal species A selected from the group consisting of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides. You may make it the structure containing 1 or more types of compounds containing the metal seed | species B. FIG. In this case, the concentration of the metal species A is preferably 0.1 to 0.7 mmol Zg, and the concentration of the metal species B is preferably 0.1 to 0.7 mmol / g. In addition, the metal species A includes one or more metals selected from lithium, sodium, calcium, strontium, barium, and lanthanum, and the metal species B includes one or more metals selected from titanium, zirconium, tantalum, and niobium. It may be configured to include metal.

[0011] In addition, the organic solvent contained in the dielectric forming composition liquid for forming the second dielectric thin film is selected from the group strength of alcohol solvents, ether solvents, ketone solvents, and ester solvents. It may be configured to include one or more organic solvents.

[0012] The step of preparing the first dielectric thin film includes an average particle diameter of particles having an ABOx-type perovskite crystal structure contained in the dielectric forming composition liquid for forming the second dielectric thin film. A first dielectric thin film forming coating step of coating a surface of a substrate with a dielectric forming composition liquid containing particles having an ABOx-type bavskite crystal structure having a larger average particle size, and the coating step And firing the resulting product to form a first dielectric thin film having an ABOx-type perovskite crystal structure on the substrate. May be.

[0013] In the first dielectric thin film forming coating step, the substrate is rotated to extend the dielectric forming composition liquid for forming the first dielectric thin film onto the substrate. After the first extension step, after the first extension step, a solvent is applied to the surface side peripheral portion of the substrate, and the surface side peripheral portion of the substrate is cleaned, and after the first cleaning step, A first drying step of rotating the substrate at a predetermined rotation speed for a predetermined time to dry the surface side peripheral portion of the substrate, and the coating step for forming the second dielectric thin film comprises A second extending step of rotating the substrate to extend the dielectric forming composition liquid for forming the second dielectric thin film on the substrate; and a surface side of the substrate after the second extending step. A second cleaning step of applying a solvent to the peripheral portion and cleaning the peripheral portion of the surface side of the substrate; and after the second cleaning step, before The substrate is rotated a predetermined time at a predetermined rotational speed, a second drying step of drying the surface-side peripheral edge of the substrate, may be configured with a.

[0014] The dielectric forming composition liquid for forming the first dielectric thin film is the second dielectric. The dielectric composition forming liquid for thin film formation may include particles having an average particle diameter of lOOnm or less having an ABOx type crystal structure obtained by hydrolysis.

[0015] The system for forming a dielectric film having an ABOx type perovskite structure according to the present invention has the above-described system on the first dielectric thin film having an ABOx type bebbitite crystal structure including voids having an average diameter of a predetermined value or more. A coating apparatus for coating a dielectric forming composition liquid containing particles having an ABOx type perovskite crystal structure having an average particle size smaller than the average diameter of the voids, and coating of the dielectric forming composition liquid by the coating apparatus And a firing device for firing the resultant product obtained by the above-described method to form a second dielectric thin film having an ABOx type bebskite crystal structure on the first dielectric thin film.

[0016] The dielectric forming composition liquid for forming the second dielectric thin film includes a metal species A and a metal species B selected from the group consisting of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides. You may make it the structure containing a 1 or more type of compound. In this case, it is desirable that the concentration of the metal species A is 0.1 to 0.7 mmolZg and the concentration of the metal species B is 0.1 to 0.7 mmol / g. In addition, the metal species A includes one or more metals selected from lithium, sodium, calcium, strontium, barium, and lanthanum, and the metal species B includes one or more metals selected from titanium, zirconium, tantalum, and niobium. It may be configured to include metal.

The invention's effect

[0017] When the dielectric film having the ABOx type perovskite crystal structure according to the present invention as described above is used for a capacitor, the leakage current can be reduced while securing a desired capacity. Brief Description of Drawings

[0018] FIG. 1 is a cross-sectional view showing an example of a capacitor using a dielectric film having an ABOx type mouth-bushite crystal structure of the present invention.

FIG. 2 is a cross-sectional view for explaining a first application process.

FIG. 3 is a cross-sectional view for explaining a first heating step.

FIG. 4 is a schematic diagram showing how the dielectric film is modified in the first heating step.

FIG. 5 is a cross-sectional view for explaining a second coating step and a second heating step.

FIG. 6 is a cross-sectional view showing an example of a method for manufacturing a capacitor according to the present invention. [7] FIG. 7 is a cross-sectional view for explaining the action of a dielectric film having an ABOx-type bottom buxite crystal structure.

[8] FIG. 8 is a plan view showing a dielectric film forming apparatus having an ABOx type bottom bskite crystal structure according to an embodiment of the present invention.

9] A perspective view of a forming apparatus according to the embodiment.

FIG. 10 is a cross-sectional view showing a schematic configuration of a coating unit included in the forming apparatus according to the embodiment.

FIG. 11 is a cross-sectional view showing a schematic configuration of a heating unit provided in the forming apparatus according to the embodiment.

FIG. 12 is a cross-sectional view showing a schematic configuration of a heating furnace that performs a baking treatment for crystallization of a coating film in the same embodiment.

13] A sectional view showing a schematic configuration of a coating unit according to another embodiment of the present invention. FIG. 14 is a cross-sectional view for explaining a cleaning process and a drying process in the embodiment.

[15] FIG. 15 is a perspective view for explaining a measurement sample used in an experiment conducted for confirming the effect of the present invention.

Explanation of symbols

21 Bottom electrode

22 Upper electrode

23 Board

25, 61 Spin chuck

26, 66 Coating liquid nozzle

3-5 dielectric film

31 First thin film

31a First coating film

32 Second thin film

32a Second coating film

40 crystal grains 41 Solvent

42 Air gap

SI carrier station

S2 processor

51 Carrier placement

6 (6A, 6B) Dispensing unit

62 cup body

63 Liquid receiver

7 (7A, 7B) Heating unit

71 Cooling plate

72 Hot plate

73 Top plate

8 Heating furnace

81 wafer boat

84 Heating means

101 rinse nozzle

W Semiconductor wafer

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a dielectric film having an ABOx type perovskite crystal structure, a capacitor using the dielectric film, and a method and a system for forming an dielectric film having an ABOx type perovskite crystal structure according to the present invention are described below. Embodiments will be described with reference to the drawings.

[0021] First, an example of a dielectric film having an ABOx type mouth bumskite crystal structure according to the present invention will be described with reference to FIG. FIG. 1 shows an example in which the dielectric film according to the present invention is applied to a capacitive element (capacitor). The capacitor shown in FIG. 1A is composed of a lower electrode 21 (for example, made of Pt), an upper electrode 22 (for example, made of A1), and a dielectric film 3.

The dielectric film 3 is a dielectric film having an ABOx-type bobsite crystal structure composed of a first thin film 31 (first dielectric thin film) layer and a second thin film 32 (second dielectric thin film) layer. It is a body membrane. And The lower electrode 21 is provided on the surface on the first thin film 31 side, and the upper electrode 22 is provided on the surface on the second thin film 32 side.

[0023] The first thin film 31 is a dielectric thin film having an ABOx type perovskite crystal structure including voids having an average diameter of lOnm or more, and the film thickness thereof is, for example, about 200 to 300 nm. . The first thin film 31 can be generated by applying a first coating liquid to a semiconductor substrate (for example, a silicon substrate) and heating. In the present embodiment, the first coating liquid is a dielectric forming composition liquid containing particles having an ABOx type perovskite crystal structure and an average particle diameter of lOOnm or less and a solvent (organic solvent).

[0024] The second thin film 32 is a dielectric thin film having an ABOx type bottom bskite crystal structure, and its film thickness is, for example, about lOOnm. The second thin film 32 can be produced by applying a second coating liquid on the first thin film 31 and heating at 700 ° C. to 900 ° C. In this embodiment, the second coating liquid is one or more compounds including a metal species A and a metal species B selected from the group of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides, and a solvent (organic solvent). ) And a dielectric composition forming liquid.

[0025] The metal species A is one or more metals selected from Li (lithium), Na (sodium), Ca (calcium), Sr (strontium), Ba (barium), and La (lanthanum). Metal species B is one or more metals selected from Ti (titanium), Zr (zirconium), Ta (tantalum), and Nb (niobium).

FIG. 1B and FIG. 1C show an example of a capacitor in which the dielectric between the lower electrode 21 and the upper electrode 22 is composed of three layers. The capacitor shown in FIG. 1 (b) includes a dielectric film 4 configured such that the first thin film 31 is sandwiched between two second thin films 32. The capacitor shown in FIG. 1 (c) includes a dielectric film 5 configured in such a manner that the second thin film 32 is sandwiched between the two first thin films 31.

Next, a method for forming the dielectric film 3 having an ABOx type perovskite crystal structure according to this embodiment of the present invention will be described with reference to FIGS. In the following description, it is assumed that barium titanate (BaTi 2 O 3) having a metal type A force ¾a and a metal type B being Ti is used as the dielectric film 3.

Three

[0028] First, the surface of the lower electrode 21 (for example, made of Pt) formed on the substrate 23 which is a silicon substrate Next, a method for forming the first thin film 31 will be described. As described above, the first thin film 31 can be produced by applying the first coating liquid to the substrate 23 (first coating process) and heating and baking (first baking process). The first coating liquid used in the present embodiment is a dielectric composition forming liquid containing particles having an ABOx type perovskite crystal structure and an average particle diameter of lOOnm or less and an organic solvent.

[0029] Here, a powerful method for producing the first coating liquid will be described. The first coating solution is produced through each step of (1) dissolution step, (2) hydrolysis step, (3) purification step, and (4) dispersion step. Hereinafter, these steps will be described in detail.

[0030] (1) Dissolution process

Well-known technologies that include one or more compounds containing metal species A constituting particles having an ABOx-type perovskite crystal structure and one or more compounds containing metal species B constituting particles having an ABOx-type perovskite crystal structure This is a step of dissolving in an organic solvent.

[0031] The compound is selected from the group of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides.

[0032] The metal species A is preferably one or more metals selected from the internal forces of Li, Na, Ca, Sr, Ba and La. The metal species B is preferably one or more metals selected from the internal forces of Ti, Zr, Ta, and Nb. More preferably, the metal species A is one or more metals selected from the internal forces of Sr and Ba, and the metal species B is Ti.

[0033] The concentration of the metal species A in the solution during dissolution is 0.1 to 0.7 mmolZg. Similarly, the concentration of metal species B is also 0.1 to 0.7 mmol Zg.

[0034] Examples of the metal alkoxide include, for example, barium alkoxides such as dimethoxybarium, diethoxybarium, dipropoxybarium, diisopropoxybarium, dibutoxybarium, and diisobutoxybarium, dimethoxystrontium, cetoxystrontium, Use strontium alkoxides such as propoxystrontium, diisopropoxystrontium, dibutoxystrontium, diisobutoxystrontium, tetramethoxytitanium, tetraethoxytitanium, tetrapropoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, tetraisobutoxytitanium, etc. Can do. [0035] Examples of the metal carboxylate include barium acetate, barium propionate, 2 methyl barium propionate, barium pentanoate, barium 2,2-dimethylpropionate, barium butanoate, barium hexanoate, 2 -Barium carboxylates such as ethylbarium hexanoate, barium octylate, barium nonanoate, barium decanoate, strontium acetate, strontium propionate, strontium 2-methylpropionate, strontium pentanoate, 2,2-dimethinorepropi Strontium carboxy such as strontium citrate, strontium butanoate, strontium hexanoate, strontium 2-ethylhexylate, strontium octylate, strontium nonanoate, strontium decanoate, etc. It can be used over door and the like.

[0036] Examples of the metal complex include titanium arylacetoacetate triisoproxide, titanium dibutoxide (bis 2,4 pentanedionate), titanium diisoproxyside (bis 2,4 pentanedio). Nate), titanium dibutoxide bis (tetramethyl heptane dionate), titanium diisoproxide bis (tetramethyl heptane dionate), titanium dibutoxide bis (ethinoreacetoacetate), titanium diisopropoxide bis ( Ethinoacetate acetate) and the like can be used.

[0037] The metal hydroxide is a compound in which a hydroxide ion is coordinated to a metal atom, and is represented by the following general formula (1).

[0038] M ^a (OH) · χΗ Ο · · · · Equation (1)

a 2

[In the formula (1), M represents a metal selected from Li, Na, Ca, Sr, Ba, La, Ti, Zr, Ta, and Nb. a is an integer of 1 to 7 according to the valence of metal M. X is an integer of 1-8. [0039] As the organic solvent, for example, alcohol solvents, polyhydric alcohol solvents, ether solvents, ketone solvents, ester solvents and the like can be used.

[0040] As the alcohol solvent, methanol, ethanol, propanol, butanol, amyl alcohol, cyclohexanol, methylcyclohexanol and the like can be used.

[0041] Examples of the polyhydric alcohol solvent include ethylene glycol monomethyl ether, ethylenic glycolenomonoacetate ester, diethylene glycolenol monomethylenether ether, jetylene glycol monoethyl acetate, propylene glycol monoethyl ether, propylene glycol. Ricohone Monoacetate, Dipropylene Glycolol Monoethyl Ethanolate, Propylene Glycol Monomethyl Ether, Propylene Glycol Monopropyl Ether, Methoxybutanol, Propylene Glycolol Monoethyl Ethenoate Ethyl Acetate, Propylene Glycol Monomethyl Ether Acetate, Dipropylene glycol propyl ether, dipropylene glycol monobutyl ether, and the like can be used.

[0042] As the ether solvent, methylal, jetyl ether, dipropyl ether, dibutyl ether, diamyl ether, jetyl acetal, dihexyl ether, trioxane, dioxane and the like can be used.

[0043] Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl cyclohexyl ketone, jetyl ketone, ethyl butyl ketone, trimethylnonanone, acetonyl acetone, dimethyl oxide. , Horn, cyclohexanone, diacetone alcohol and the like can be used.

[0044] Examples of the ester solvent include ethyl formate, methyl acetate, ethyl acetate, butyl acetate, cyclohexyl acetate, methyl propionate, ethyl butyrate, ethyl oxyisobutyrate, ethyl acetate, ethyl acetate, methoxybutyl acetate, Jetyl oxalate, jetyl malonate and the like can be used.

[0045] The organic solvent may be one of the above-mentioned solvents, or may be a combination of two or more solvents.

Note that the solution generated in the dissolution step corresponds to a second coating solution for forming the second thin film 32.

[0047] (2) Hydrolysis step

In this step, water is added to the solution produced in the dissolution step, and the precursor in the solution is hydrolyzed to obtain crystal particles.

[0048] During hydrolysis, the solution temperature is usually kept in the range of -78 ° C to 200 ° C from the viewpoint of reaction efficiency. In this case, it is preferably −20 ° C. to 100 ° C., and more preferably 0 to 50 ° C.

[0049] The amount of water added to the solution during hydrolysis is usually 5 to 300 times the molar amount of 1 mol of metal species A. In this case, the molar amount is preferably 10 to 200 times (20 A molar amount of ~ 100 times is even more preferable. ). When water is added in such a molar amount, the crystallinity of the particles is improved and the dispersibility is also improved.

[0050] In addition to adding only water to the solution, a mixture of one or more solvents selected from the above-described plurality of solvents and water may be added.

[0051] Further, the water to be added contains a catalyst! For example, acid catalysts such as inorganic acids (eg hydrochloric acid, sulfuric acid, nitric acid), organic acids (eg acetic acid, propionic acid, butyric acid, maleic acid), sodium hydroxide, potassium hydroxide, barium hydroxide, ammonia, Inorganic or organic alkali catalysts such as monoethanolamine, diethanolamine, and tetramethylammonium hydroxide can be used as the catalyst.

[0052] Hydrolysis condensate produced after adding water is usually 0.5 to 10 at 200 to 200 ° C.

Hold for 200 hours. In this case, it is preferable to hold for 1 to: LOO time at 20 to 150 ° C.

It is more preferable to hold at 30 to 100 ° C for 3 to 20 hours.

[0053] Through the dissolution step and the hydrolysis step, crystal particles having an ABOx type perovskite crystal structure and an average particle size of lOOnm or less (preferably an average particle size of 20 to 80 nm) can be obtained.

[0054] (3) Purification step

In this step, the crystal particles obtained in the hydrolysis step are purified with an organic solvent. As a method for purifying the crystal particles with an organic solvent, any method may be used as long as the crystal particles and the organic solvent can be separated after purification. For example, first, an organic solvent is added to the crystal particles, and the decantation is! /, Sediments the crystal particles by centrifugation, and removes the supernatant. Then, there is a method in which the process of adding the organic solvent to the precipitated crystal particles and heating again is repeated 2 to 5 times.

[0055] Examples of the organic solvent used in this case include alcohol solvents, polyhydric alcohol solvents, ether solvents, ketone solvents, ester solvents, and the like. As these organic solvents, those exemplified in the section of the dissolution step can be used.

[0056] (4) Dispersion process

In this step, the crystal particles purified by the purification step are dispersed in an organic solvent. Specifically, first, the crystal particles obtained in the purification step are separated from an organic solvent which is a washing solution. Then, the separated crystal particles are put into a new organic solvent and dispersed to produce a crystal particle dispersion.

[0057] As a method for dispersing the crystal particles in the organic solvent, any method may be used as long as the crystal particles can be uniformly dispersed in the organic solvent. For example, adopt a method in which crystal particles are dispersed in a solvent while performing mechanical stirring, stirring using ultrasonic waves, or the like.

[0058] Examples of the organic solvent used for dispersion include alcohol solvents, polyhydric alcohol solvents, ether solvents, ketone solvents, and ester solvents. Further, the organic solvent used for dispersion may be the same as or different from the organic solvent used in the purification step.

[0059] In consideration of the stability of the crystal particle dispersion, the content of the crystal particles in the crystal particle dispersion is 1 to 20% by weight (preferably 3 to 15% by weight) of the entire crystal particle dispersion as a solid content concentration. ).

[0060] In order to facilitate the dispersion of the crystal particles, when dispersing the separated (purified) crystal particles in a new organic solvent, a non-one surfactant, a key-on surfactant, Cationic surfactants may be used as dispersants!

[0061] Examples of such surfactants include polyoxyethylene polyoxypropylene glycol, polyoxypropylene polyoxyethylene condensate of ethylenediamine (pull-mouth type), sodium alkylbenzene sulfonate, polyethylene Imine, polyvinylpyrrolidone, perfluoroalkyl group-containing oligomers and the like can be used.

[0062] The type and amount of the dispersing agent can be appropriately selected and used depending on the type of crystal particles and the type of solvent in which the crystal particles are dispersed. In this case, considering the dielectric properties of the dielectric film obtained in the present embodiment, the amount of additive is preferably 0.001 to 10 g with respect to the crystal particle lOOg.

[0063] By passing through the above steps, a dielectric forming composition liquid comprising an organic solvent and particles having an ABOx type perovskite crystal structure and an average particle size of 100 nm or less (preferably an average particle size of 20 to 80 nm) A certain first coating solution can be obtained.

[0064] Next, a process of applying the first coating solution obtained as described above to the substrate 23 (first coating process) will be described. This process is performed in a coating unit (described later). The

First, as shown in FIG. 2 (a), the center part on the back surface side of the substrate 23 on which the lower electrode 21 is formed is held by the spin chuck 25. Then, the first coating liquid is discharged from the coating liquid nozzle 26, and the first coating liquid is applied to the surface of the lower electrode 21.

[0066] Subsequently, the substrate 23 is rotated by the spin chuck 25 at a predetermined rotation speed (for example, about 2000 rpm). Then, the first coating liquid extends toward the peripheral edge of the substrate 23 by the centrifugal force of rotation (see FIGS. 2 (b) and 2 (c)).

[0067] Thereafter, the substrate 23 is rotated at a predetermined rotation speed (for example, about 1500 rpm). Then, the excess first coating liquid is shaken off, and a coating film (first coating film 31a) of the first coating liquid having a predetermined thickness (for example, 200 ηm) is formed on the surface of the lower electrode 21 ( (See Figure 2 (d)).

FIG. 4 (a) schematically shows the state of the first coating film 31a formed as described above. As shown in FIG. 4 (a), it is presumed that most of the crystal particles 40 are dispersed in the solvent 41, and a part of them generates barium titanate.

Next, a method of forming the first thin film 31 by heating the first coating film 31a formed as described above will be described.

[0070] First, in the heating unit described later, as shown in FIG. 3 (a), the first coating film 31a formed on the surface of the lower electrode 21 is subjected to a predetermined temperature (for example, 250 ° C). Heat for 1 minute (beta treatment). By the beta treatment, which is a pretreatment for the baking, the solvent 41 contained in the first coating film 31a is volatilized. In addition, hydrolysis occurs and the coating film becomes gelled, and further condensation occurs. As a result, as shown in Fig. 4 (b), it is presumed that a network structure of barium titanate, which is a precursor film of barium titanate having an ABOx type perovskite crystal structure, is formed. Further, when the solvent 41 volatilizes, crystal particles aggregate due to the action of the binder in the coating film, and the crystal particles become large.

Subsequently, as shown in FIG. 3 (b), the first coating film 31a formed on the surface of the lower electrode 21 on the substrate 23 is subjected to a predetermined temperature by using a baking apparatus described later. (For example, 800 ° C) Heat for 60 minutes (first firing step). By this baking treatment, a change proceeds to an amorphous state force crystallization state in the first coating film 31a. As a result, as shown in FIG. 4 (c), a first thin film 31 made of a barium titanate film having an ABOx type bottom bumskite crystal structure is formed. Is done. This ABOx-type perovskite crystal structure ranges from 2.5 to 3.5 in terms of the X O value of AB Ox depending on the oxygen supersaturation or deficiency.

[0072] The first thin film 31 formed in this way is a thin film containing barium titanate crystal particles having an average particle diameter of 50 nm or more and lOO nm or less. And the film thickness is 200ηπ! ~ 300nm. The first thin film 31 has a porous structure, and a large number of fine voids having an average diameter of lOnm or more are formed.

Next, a method for forming the second thin film 32 on the surface of the first thin film 31 formed as described above will be described.

First, the step of applying the second coating liquid to the surface of the first thin film 31 (second coating step) will be described. This step is performed in a coating unit (described later) in the same manner as the first coating step described above. The second coating liquid, which is a dielectric forming composition liquid, is generated in the manufacturing process of the first coating liquid (more specifically, the above-described dissolution process).

[0075] If the concentration of the first coating solution is too high, the first coating solution will not enter the voids of the first thin film 31, as will be described later. Accordingly, it is desirable that the concentration of the metal species A contained in the first coating solution is 0.1 to 0.7 mmolZg and the concentration of the metal species B is 0.1 to 0.7 mmolZg. Further, when the above-described alcohol solvent, ether solvent, ketone solvent, ester solvent or the like having good wettability with respect to the first thin film 31 is used as the organic solvent, the permeability is further increased.

[0076] The second coating liquid as described above is supplied almost to the center of the first coating film 31 on the substrate 23.

(See Figure 5 (a)). Subsequently, the substrate 23 is rotated at a predetermined rotation speed (for example, about 2000 rpm). Then, the first coating liquid extends toward the peripheral side of the substrate 23 by the centrifugal force of rotation. Thereafter, the substrate 23 is rotated at a predetermined rotation speed (for example, about 1500 rpm). Then, the excess second coating liquid is shaken off, and a coating film (second coating film 32a) of the second coating liquid having a predetermined thickness (for example, 180 nm) is formed on the surface of the first thin film 31. (See Fig. 5 (b)). In this state, most of the crystal particles are in a state of being dispersed in the solvent, and it is presumed that a part of them generates barium titanate.

[0077] Next, a method for forming the second thin film 32 by heating the second coating film 32a formed as described above will be described. First, in the heating unit described later, as shown in FIG. 5 (c), the second coating film 32a formed on the surface of the first thin film 31 is subjected to a predetermined temperature (eg, 250 ° C.). Heat for 1 minute at (heat treatment). The organic solvent contained in the second coating film 32a is volatilized by the heat treatment before firing (that is, beta treatment). In addition, hydrolysis occurs, the coating film becomes gelled, and further condensation polymerization occurs. As a result, a network structure of barium titanate is formed which becomes a precursor film of barium titanate having an ABOx type perovskite crystal structure.

[0079] Subsequently, as shown in Fig. 5 (d), the second coating film 32a is applied to a temperature of about 700 ° C to 900 ° C (for example, 800 ° C) in a baking apparatus described later. For 60 minutes (second baking step). By this baking treatment, the state changes into an amorphous state force crystallization state inside the second coating film 32a. As a result, a second thin film 32 made of a barium titanate film having an ABOx-type bottom buxite crystal structure is formed. In this ABOx-type mouthbushite crystal structure, the X value of ABOx is in the range of 2.5 to 3.5 depending on the oxygen supersaturation or deficiency.

[0080] The second thin film 32 formed in this way has an ABOx type perovskite crystal structure, and its film thickness is about lOOnm. The second thin film 32 is a thin film containing barium titanate crystal particles having an average particle size smaller than that of the first thin film 31. More specifically, the average particle diameter of the crystal particles is 10 nm or more and 50 nm or less. This average particle diameter was calculated by the present inventors based on a photograph taken with a SEM (scanning electron microscope, manufactured by Hitachi High-Tech).

[0081] Further, like the first thin film 31, the second thin film 32 also has a porous structure, and many finer voids are formed than the voids (average diameter is lOnm or more) of the first thin film 31. RU

As described above, dielectric film 3 (see FIG. 1 (a)) having an ABOx type perovskite crystal structure is formed.

Here, when the electrode (upper electrode 22) is formed on the upper surface of the dielectric film 3, the capacitor shown in FIG. 1 (a) is obtained. Specifically, as shown in FIG. 6 (a), the upper electrode 22 can be formed by sputtering the upper side force of the second thin film 32 with, for example, A1 using a sputtering apparatus (not shown) (FIG. 6 (b)). )reference).

As described above, according to the dielectric film having the ABOx type perovskite crystal structure and the method for forming the same according to the embodiment of the present invention, the following excellent actions and effects are obtained. To do.

[0085] (1) The first coating solution is a special solution obtained by hydrolyzing and dispersing the second coating solution, and as described above, the first coating film 31a is subjected to a beta treatment. Therefore, aggregation of particles occurs when the organic solvent in the first coating film 31a is volatilized. Therefore, even if the second thin film 32 is formed by substantially the same process, the average grain size of the crystal particles constituting the first thin film 31 is larger than that of the crystal particles constituting the second thin film 32. Specifically, the average grain size of the crystal grains constituting the first thin film 31 is not less than 50 nm and not more than lOOnm. For this reason, it is possible to secure a film thickness of, for example, about 200 nm to 300 nm by applying the first coating liquid once.

[0086] Since the second thin film 32 can secure a film thickness of, for example, about lOOnm by one application, the first thin film 31 and the second thin film 32 are stacked one by one. Thus, the dielectric film 3 having an ABOx type perovskite crystal structure with a thickness of 300 nm to 400 nm can be formed. That is, the number of stacked layers when forming a dielectric film having a desired thickness can be reduced. Thus, since the number of times of heating can be reduced while securing a desired capacitor capacity, the grain growth of barium titanate can be suppressed, and the occurrence of leakage current caused by this can be suppressed.

(2) By forming the second thin film 32 on the upper layer side of the first thin film 31, the voids of the first thin film 31 can be filled with particles constituting the second thin film 32. Thereby, a dense (high density) layer is formed on the surface of the first thin film 31, and the flatness of the surface of the dielectric film 3 is improved. Specifically, the first thin film 31 has a porous structure when heated for crystallization as described above, and the average grain size of the crystal grains constituting the thin film is 50 nm or more and lOOnm or less. For this reason, as shown in FIG. 7 (a), the average diameter of the voids 42 formed between the crystal particles 40 in the first thin film 31 is not less than lOnm. Accordingly, the surface of the first thin film 31 is uneven due to the presence of voids in the porous structure. However, since both the crystal particles 40 and the voids 42 are large, the flatness is poor and is in a state.

[0088] However, the average diameter of the voids 42 is larger than the average particle diameter of the particles serving as the precursor of the second thin film 32 contained in the second coating liquid. For this reason, as shown in FIG. 7 (b), in the step of applying the second coating liquid onto the surface of the first thin film 31 (second coating step), the gap 42 is filled with the second Particles 43 that make up the coating liquid enter and penetrate into the interior. As a result, as shown in FIG. 7C, in the boundary region between the first thin film 31 and the second thin film 32, the particles 43 are embedded in the voids 42. That is, the void 42 of the first thin film 31 is blocked by the particles 43 constituting the second thin film 32 (second coating liquid). Therefore, in this boundary region, it is presumed that the film becomes denser than the second thin film 32 composed of fine crystal particles.

[0089] In this case, as described above, the concentrations of the metal species A and the metal species B in the second coating solution are 0.1 to 0. 0.

When the organic solvent is set to 7 mmolZg and an organic solvent having good wettability with respect to the first thin film 31 is selected, the second coating liquid can easily penetrate into the voids 42 of the first thin film 31. In fact, when the present inventors observed with a TEM (transmission electron microscope, manufactured by Hitachi High-Tech) and SEM (scanning electron microscope, manufactured by Hitachi, Tech), the first thin film 31 had a gap 42. It was observed that the coating solution of 2 entered and went away.

[0090] As described above, the voids 42 formed on the surface of the first thin film 31 are blocked by the particles 43 constituting the second coating liquid, so that the flatness of the surface of the first thin film 31 is improved. . In addition, since the second thin film 32 is formed on the surface of the first thin film 31 having high flatness, the flatness of the surface of the second thin film 32 is also improved.

In addition, by adopting a configuration in which the second thin film 32 is formed on the first thin film 31, the leakage characteristics of the dielectric film can be improved. The reason for this is as follows. The first reason is that the crystal grains of the second thin film 32 are very small. That is, as described above, since the crystal particles of the second thin film 32 are very small (average particle size is about 20 nm), even if a porous structure is formed by heating for crystallization, voids formed thereby are formed. Is quite small.

Accordingly, in the step of forming the upper electrode 22 by sputtering A1 on the surface of the second thin film 32, the second thin film 32 has a small gap, so that the snow / tag particles are difficult to enter. Therefore, even when the first thin film 31 is fired or the second thin film 32 is fired, even if the Pt particles of the lower electrode 21 penetrate from the lower side of the first thin film 31 due to thermal diffusion, It can be said that it is difficult to contact. Therefore, it is possible to suppress the generation of a leakage current that is difficult to form a conductive path between the Pt particles and the sputtered particles.

[0093] The second reason is that a dense layer (high density) is formed at the boundary between the first thin film 31 and the second thin film 32. Even if the Pt particles in the lower electrode 21 penetrate from the lower side of the first thin film 31 due to thermal diffusion, the vicinity of the boundary between the first thin film 31 and the second thin film 32 is formed. It is difficult to penetrate beyond the second thin film 32 side. This also applies to the case where A1 (sputtered particles) penetrates into the second thin film 32 during the process of forming the upper electrode 22 by sputtering A1 on the surface of the second thin film 32. It is the same. That is, since the boundary region between the first thin film 31 and the second thin film 32 is denser than the second thin film 32, the sputtered particles permeate the first thin film 31 side beyond the region. Is difficult! For this reason, the formation of the vertical conduction path of the dielectric film 3 having the ABOx type bevskite crystal structure composed of the first thin film 31 and the second thin film 32 is suppressed, and as a result, leakage occurs. Generation of current can be suppressed.

It should be noted that the capacitors having the structures shown in FIG. 1 (b) and FIG. 1 (c) also have an ABOx type base having a desired film thickness by laminating the first thin film 31 and the second thin film 32. The dielectric film 4 or the dielectric film 5 having an oral bskite crystal structure can be obtained. Specifically, in the case of the capacitor having the structure shown in FIG. 1 (b), the first thin film 31 located in the middle of the dielectric film 4 and the second layer located on the third layer (on the upper electrode 22 side) are located. The boundary area with the thin film 32 becomes dense, and the boundary surface becomes flat. In the case of the capacitor having the structure shown in FIG. 1 (c), the first thin film 31 located on the first layer of the dielectric film 5 (on the lower electrode 21 side) and the second thin film 32 located in the middle The boundary area becomes dense, and the boundary surface becomes flat. Therefore, a desired capacitor capacity can be secured for both capacitors, and the occurrence of leakage current can be suppressed.

Next, a system for forming a dielectric film having an ABOx type perovskite crystal structure according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 8 is a schematic plan view of a forming apparatus provided in the dielectric film forming system according to the present embodiment, and FIG. 9 is a perspective view of the forming apparatus. 8 and 9, S1 is a carrier station. In S1, a carrier placing part 51 and delivery means 52 are provided. The carrier placement unit 51 places a carrier C that stores a plurality of (for example, 25) wafers W. The delivery means 52 delivers the wafer W to and from the carrier C.

[0097] A processing unit S2 surrounded by a casing 53 is connected to the back side of the delivery means 52. A main transfer means 54 is provided in the center of the processing section S2. Near main transport means 54 In the vicinity, there are a plurality of coating units 6 and shelf units Ul, U2, U3, each of which is a stack of heating and cooling units and the like. Further, as the coating unit 6, a first coating unit 6A (not shown) for performing the coating process of the first coating liquid and a second coating unit 6B (not shown) for performing the coating process of the second coating liquid. ) Is prepared.

[0098] The shelf units Ul, U2, U3 are configured by combining various units for performing pre-processing and post-processing of the coating unit 6 and the like. The combination includes a heating unit 7 for performing a heating process (baking process) and a delivery unit for the wafer W, which is one of the shelves of the shelf unit U3. The heating unit 7 functions as a heating device that heats (beta) W and W coated with the coating liquid on the surface by the coating unit 6 and volatilizes the solvent in the coating liquid. Further, as the heating unit 7, a first heating unit 7A (not shown) for performing the heat treatment of the first coating film 31a and a second heating unit 7B (not shown) for performing the heat treatment of the second coating film 32a. Is prepared). The main transport means 54 is configured to be movable in the vertical direction and the horizontal direction and to be rotatable about the vertical axis. By virtue of the powerful configuration, the main transport means 54 can transfer wafers W between the units constituting the coating unit 6 and the shelf units Ul, U2, U3.

The flow of each process performed by the dielectric film forming apparatus having the above configuration will be described. First, the carrier C force in which UENO and W are stored is taken in from the outside and placed on the carrier placing portion 51. On the surface of the wafer W accommodated in the carrier C, a lower electrode 21 is formed. Next, the wafer W is taken out from the carrier C by the delivery means 52 and delivered to the main transport means 54 via the delivery unit which is one of the shelves of the shelf unit U 3. The main transfer means 54 transfers the wafer W to the first coating unit 6A.

[0100] In the first unit 6A, a process of applying the first application liquid onto the surface of the lower electrode 21 on the transferred wafer W is performed. Thereafter, the wafer W is transferred to the first heating unit 7A and subjected to heat treatment (beta treatment). After the beta processing, the wafer W is once returned into the carrier C on the carrier mounting portion 51 via the main transfer means 54 and the delivery means 52. The wafer W returned to the carrier C is transferred to a baking apparatus described later and is baked by the baking apparatus. Thereby, the first thin film 31 is formed (first firing step).

[0101] The wafer W that has finished the first baking step is transferred to the second through the delivery means 52 and the main transfer means 54. It is conveyed to the coating unit 6B. In the second coating unit 6B, a process of coating the second coating solution on the surface of the first thin film 31 formed on the transferred wafer W is performed. After that, the wafer W is transferred to the second heating unit 7B and subjected to heat treatment (beta treatment). After the beta processing, the wafer W is once returned into the carrier C on the carrier mounting portion 51 via the main transfer means 54 and the delivery means 52. The wafer W returned to the carrier C is transferred to a baking apparatus described later and is baked by the baking apparatus (baking process). Thereby, the second thin film 32 is formed (second baking step).

[0102] Next, the application unit 6 that performs the application process will be briefly described with reference to FIG. FIG. 10 is a cross-sectional view showing a schematic configuration of the coating unit 6 according to the present embodiment. The first coating unit 6A and the second coating unit 6B have the same configuration as the coating unit 6.

In FIG. 10, reference numeral 61 denotes a spin chuck configured to be rotatable and movable up and down around a vertical axis in order to suck and adsorb the central portion on the back side of the wafer W and hold it substantially horizontally. A cup body 62 having an opening on the upper side so as to surround the wafer W is provided outside the periphery of the wafer W held by the spin chuck 61. On the bottom side of the cup body 62, a recess-shaped liquid receiving portion 63 is provided on the lower peripheral edge of the wafer W over the entire circumference.

[0104] Reference numeral 64 denotes a drainage path for discharging a drain such as a coating liquid, and reference numeral 65 denotes an exhaust path. Reference numeral 66 denotes a coating liquid nozzle for supplying a first coating liquid (second coating liquid) to the wafer W held on the spin chuck 61.

[0105] The coating process performed in the coating unit 6 configured as described above will be described.

First, the spin chuck 61 is positioned above the cup body 62. Then, V (not shown) and the wafer W transferred by the transfer means are placed on the spin chuck 61 by a cooperative action with the lift pins (not shown). Next, the spin chuck 61 is lowered to the processing position shown in FIG. Then, the first coating liquid (second coating liquid) is applied from the coating liquid nozzle 66 to approximately the center of the wafer W held by the spin chuck 61. Further, by rotating the wafer W by the spin chuck 61, the first coating liquid (second coating liquid) spreads over the entire surface of the wafer W.

Subsequently, the heating unit 7 that performs the beta process will be described with reference to FIG. The first The first heating unit 7A and the second heating unit 7B have the same configuration as the heating unit 7. As shown in FIG. 11 (a), a base 75 formed in a cylindrical shape with a bottom is provided inside the casing 70 of the heating unit 7. In addition, for example, a circular heat plate 72 is provided in the base 75. When the wafer W is loaded onto the cooling plate 71 in the housing 70, the wafer W is transferred to the hot plate 72 by the cooling plate 71. When the wafer W is placed on the hot plate 72, as shown in FIG. 11 (b), the rectifying top plate 73 is lowered and the peripheral portion of the top plate 73 and the base are placed via the O-ring 74. 75 peripheral portions are in close contact with each other. As a result, the periphery of the wafer W becomes a sealed space. Thereafter, for example, while supplying gas into the sealed space from the gas supply unit 76, suction and exhaust are performed from the exhaust port 78 in the center of the top plate 73 by the suction mechanism 77. In this way, the heat treatment is performed while forming an airflow (see the arrow in FIG. 11 (b)) directed from the outer periphery of the wafer W toward the center.

[0107] Next, a firing apparatus provided in the dielectric film formation system according to the present embodiment will be described. FIG. 12 is a schematic configuration diagram of a heating furnace 8 which is an example of a baking apparatus. The heating furnace 8 is a baking apparatus for changing the internal state of the coating film after the beta treatment into an amorphous state force crystallization state. As shown in FIG. 12, the heating furnace 8 includes a vertical reaction tube 80 having a double tube structure, for example. A plurality of wafers W are accommodated in the wafer boat 81 in the reaction tube 80 at a predetermined interval in the vertical direction. In this state, for example, gas is supplied from the gas supply pipe 82 into the reaction pipe 80 and the suction pipe 83 is used to suck and exhaust the reaction pipe 80. In this way, the wafer W is baked by the heating means 84 provided outside the reaction tube 80 while forming a gas stream.

[0108] Next, another embodiment of the present invention will be described. The method for forming the dielectric film 3 having an ABOx-type perovskite crystal structure according to the present embodiment is the first coating film 31a on the surface of the substrate (wafer W) on which the lower electrode 21 is formed as shown in FIG. After the surface is formed, a first cleaning step (side rinsing treatment) for cleaning the peripheral edge of the surface of the substrate with a solvent, and a first drying step (spinning) for rotating the substrate to dry the solvent After the second coating film 32a is formed on the surface of the first thin film 31, as shown in FIG. 5, the second cleaning step (side Rinse treatment) and a second drying step (spin drying treatment) for rotating the substrate to dry the solvent. The other features are the same as those of the above-described embodiment.

First, the application unit 6 (6A, 6B) that performs the side rinse process and the spin drying process will be briefly described with reference to FIG. In FIG. 13, parts having the same configuration as the coating unit 6 shown in FIG. 10 described above are denoted by the same reference numerals and description thereof is omitted.

As shown in FIG. 13, in the coating unit 6 of the present embodiment, the rinse nozzle 101 for supplying the solvent R to the peripheral portion on the surface side of the wafer W is provided so as to be inclined outward and downward. The discharge port of the lens nozzle 101 is configured such that the discharged solvent R reaches the peripheral edge of the wafer W from above and from the inside. The rinse nozzle 101 is connected to a solvent supply source 103 via a supply device group 104 including a solvent supply pipe 102, a valve, a flow rate adjusting unit, and the like.

[0111] Further, the coating liquid nozzle 66 can move from the standby region 69 provided on the outer side of one end side (right side in FIG. 13) of the cup body 62 to the other end side and move in the vertical direction. It is configured. Further, the rinse nozzle 101 is configured to be able to move from one standby side 107 provided on the outside of the other end side (left side in FIG. 13) of the cup body 62 to one end side and to move in the vertical direction. RU

Next, the operation of the present embodiment will be described with reference to FIG. First, the wafer W on which the lower electrode 21 is formed is placed on the spin chuck 61 by the cooperative operation of the main transfer means 54 (see FIG. 8) and the spin chuck 61. Subsequently, the first coating solution is applied to the central portion on the front side of the wafer W by the method described above (see FIG. 2 (a)) (FIG. 14 (a)). In FIG. 2 (a), the force that applies the first coating liquid 31 to the center of the front side of the wafer W while the wafer W is stopped. The surface of the wafer W is rotated when the wafer W rotates. You may apply | coat the 1st coating liquid 31 to the side center part.

[0113] Then, after the first coating solution 31 has spread over the entire surface of the wafer W by the method described above (see Figs. 2 (b) and 2 (c)), the method described above (Fig. 2 (d ))), The excess first coating solution 31 is spun off to form the first coating film 31a (FIG. 14 (b)).

[0114] Next, a predetermined amount of solvent is applied from the rinse nozzle 101 to a range of, for example, 3 mm from the surface side peripheral edge to the center of the wafer W while rotating the wafer W at a low speed. Then, the solvent R applied to the peripheral edge of the front surface of the wafer W spreads toward the peripheral edge, and the surface side of the wafer W The first coating film 31a at the peripheral edge is dissolved (so-called side rinse). As shown in FIG. 14C, the dissolved first coating film 31a is shaken off together with the solvent R by the rotation of Ueno and W (first cleaning process). Thereafter, the wafer W is rotated at a predetermined rotation speed (for example, 200 Orpm or more) for a predetermined time (for example, 20 seconds or more) to perform swing-off drying (so-called spin drying), as shown in FIG. 14 (d). Thus, the solvent R remaining on the peripheral edge of the wafer W is volatilized (first drying step). In this spin drying, it is preferable to rotate at a rotation speed of 5000 rpm or more for 20 seconds or more (more preferably, rotation at a rotation speed of 5000 rpm or more for 60 seconds or more).

[0115] Next, in the heating unit, the first coating film 31a formed on the surface of the lower electrode 21 of the wafer W is heated by the above-described method (see FIG. 3A) (beta treatment). . Subsequently, in the baking apparatus, the first thin film 31 is formed by performing the baking process by the method described above (see FIG. 3B).

[0116] Subsequently, in the second coating unit 6B having the same configuration as the first coating unit 6A described above, the second thin film 32 is formed in the same manner as the first thin film 31 forming method described above. Form . That is, the second coating solution is applied to the front surface side central portion of the wafer W on which the first thin film 31 is formed (FIG. 14 (a)), spread over the entire surface of the wafer W, and an extra second coating solution. The liquid 32 is shaken off to form a second coating film 32a (FIG. 14 (b)). Then, after performing the side rinse process (second cleaning process) shown in FIG. 14 (c) and the spin drying process (second drying process) shown in FIG. 14 (d), the baking process and the baking process are executed. Thus, the second thin film 32 is formed.

As described above, the dielectric film 3 having the ABOx type perovskite crystal structure according to the present embodiment is formed.

[0118] Here, when the electrode (upper electrode 22) is formed on the upper surface of the second thin film 32 by the above-described method using a sputtering apparatus (not shown), as shown in FIG. 1 (a). A dielectric film having an ABOx type perovskite crystal structure in which a first thin film 31 and a second thin film 32 are laminated in this order between the lower electrode 21 and the upper electrode 22 in this order. Capacitors with can be obtained.

As described above, according to the present embodiment, after removing the first coating film 31a (second coating film 32a) on the surface side peripheral portion of the wafer W with the solvent R, the wafer W is moved at high speed (for example, 5000rpm The solvent R remaining on the peripheral edge of the wafer W can be sufficiently volatilized by rotating for a predetermined time (for example, 60 seconds or more) in the above manner. If beta treatment or baking treatment is performed while the solvent R remains on the peripheral edge of the wafer W, the non-volatile solvent R inhibits crystallization of the barium titanate (BaTi03) at high temperatures. As a result, the barium titanate constituting the first coating film 31a (second coating film 32a) becomes a crystal with a broken composition ratio. When the first coating film 31a (second coating film 32a) is in such a state, the solvent R penetrates and the solvent R adheres to the film. As a result, a conduction path is formed by the carbon contained in the solvent R, and the leakage current increases.

Therefore, by performing spin drying at a predetermined rotational speed for a predetermined time after the side rinse treatment as in the present embodiment to volatilize the solvent R at the peripheral edge of the wafer W, it is possible to suppress the leakage current due to the energization path. it can.

Example

[0121] Next, examples of experiments conducted to confirm the electrical characteristics of the dielectric film having the ABOx type perovskite crystal structure will be described.

(Example 1)

In this example, a sample for measuring electrical characteristics as shown in FIG. 15 was used. Here, a procedure for manufacturing a sample for measuring electrical characteristics used in this example will be described. First, the surface of the silicon substrate 91 is oxidized and a Si02 film 92 having a thickness of about lOO nm is formed on the upper layer side. Then, a Pt layer 93 as a lower electrode is formed thereon. The thickness of the Pt layer 93 is about 3 Onm.

Next, the dielectric film 3 having an ABOx type perovskite crystal structure to be measured is formed on the upper surface of the Pt layer 93. Then, an aluminum (A1) layer 94 as an upper electrode is formed on the upper surface of the dielectric film 3. Subsequently, this A1 layer 94 is put into a disk shape having a diameter of about 0.25 mm to 10 mm. Then, the dielectric film 3 is patterned into the shape shown in FIG. 15, and the Pt layer 93 is exposed.

[0123] In addition, the dielectric film 3 to be measured is a titanium film having an ABOx-type perovskite crystal structure on a first thin film 31 having a thickness of 200 nm and made of ABOx-type bottom-bushite crystal structure. A second thin film 32 made of barium oxide and having a thickness of lOOnm is laminated. This The first thin film 31 and the second thin film 32 are formed by the method described in the above embodiment.

[0124] The measurement device 95 is connected to the electrical property measurement sample manufactured as described above (connected between the Pt layer 93 and the A1 layer 94), and the leakage current of the dielectric film 3 and the dielectric The capacitance of membrane 3 was measured.

[0125] With respect to the leakage current of dielectric film 3, a 2 V bias voltage was applied between Pt layer 93 and A1 layer 94 for 15 seconds at room temperature, and the unit area flowing in dielectric film 3 at that time was The average value of the current per contact was detected.

[0126] Also, regarding the electric capacity of dielectric film 3! /, At room temperature, bias voltage is OV or IV, Vrms (capacitance measurement AC voltage) is 10mV, and frequency is lkHz to lMHz. A voltage was applied between the Pt layer 93 and the A1 layer 94, the current and frequency flowing at that time were detected, and the resultant force was also calculated.

As a result, the leakage current of the dielectric film 3 in which the first thin film 31 and the second thin film 32 are laminated is ^8.1 × 10 ^_8 AZcm ² , and the electric capacity is ^1.2 μY. It was / cra.

[0128] (Comparative Example 1)

As the dielectric film 3 used for the electrical property measurement sample, a dielectric film having only a 200 nm-thick first thin film 31 made of barium titanate having an ABOx type perovskite crystal structure was prepared. Using this, the leakage current and the electric capacity were measured in the same manner as in Example 1. The first thin film 31 is formed by the method described in the above embodiment. As a result, the leakage current is 1. a 3 X 10 ^_2 AZcm ^2, the electric capacity is rarely at 0. 9 F / cm.

[0129] (Comparative Example 2)

As the dielectric film 3 used for the electrical property measurement sample, a dielectric film having only a second thin film 32 of lOOnm thickness made of barium titanate having an ABOx type perovskite crystal structure was prepared. Using this, the leakage current and the electric capacity were measured in the same manner as in Example 1. The second thin film 32 is formed by the method described in the above embodiment. As a result, the leakage current was 2.8 X 10 ^_3 AZcm ² and the electric capacity was 0.7 F, cm 2. [0130] From the above results, when the dielectric film 3 having the first thin film 31 and the second thin film 32 (Example 1) is used, the first thin film 31 is used. It was confirmed that the leakage current was larger and the leakage current was smaller than in the case of using only the configuration including only the first thin film (Comparative Example 1) and the configuration including only the second thin film 32 (Comparative Example 2). As a result, the dielectric film 3 having the ABOx type bottom bskite crystal structure of the present invention including the first thin film 31 and the second thin film 32 formed on the upper layer side is used as a dielectric thin film of the capacitor. It is understood that high electrical characteristics can be secured when used.

[0131] (Example 2)

The sample for measuring electrical characteristics used in this example uses the dielectric film 3 formed through the above-described side rinse treatment and spin drying treatment (see FIG. 14). Except this point, the sample is the same as the sample for measuring electrical characteristics of Example 1. Using this, the leakage current and the capacitance were measured under the same conditions as in Example 1. In the spin drying process, the rotation speed and rotation time of the silicon substrate 91 were set to 5000 rpm and 60 seconds, respectively.

[0132] As a result, the leakage current of the dielectric film 3 is 1. a 3 X 10 ^_9 AZcm ^2, electrical capacitance, 1. 4 μ Y / cm (? Rarely.

[0133] (Example 2-1)

The electrical property measurement sample used in this example uses a dielectric film 3 formed through a side rinse process and a spin drying process as in the second example. Then, using this, the leakage current and the capacitance were measured under the same conditions as in Example 1. In the spin drying process, the rotation speed and rotation time of the silicon substrate 91 were set to 2000 rpm and 20 seconds, respectively.

As a result, the leakage current of the dielectric film 3 was 8. IX 10 ^_8 AZcm ² , and the electric capacity was 1.2 μ ¥ / cm (?

[0135] (Example 2-2)

The electrical property measurement sample used in this example uses a dielectric film 3 formed through a side rinse process and a spin drying process as in the second example. Then, using this, the leakage current and the capacitance were measured under the same conditions as in Example 1. In the spin drying process, the rotation speed and rotation time of the silicon substrate 91 are set to 4000 rpm and 20 rpm, respectively. Seconds.

As a result, the leakage current of the dielectric film 3 was ^8.8 × 10 ^_8 AZcm ² , and the electric capacity was 1.2 μ ¥ / cm (?

[0137] (Example 2-3)

The electrical property measurement sample used in this example uses a dielectric film 3 formed through a side rinse process and a spin drying process as in the second example. Then, using this, the leakage current and the capacitance were measured under the same conditions as in Example 1. In the spin drying process, the rotation speed and rotation time of the silicon substrate 91 were set to 5000 rpm and 20 seconds, respectively.

As a result, the leakage current of the dielectric film 3 was ^9.5 × 10 ^_8 AZcm ² , and the electric capacity was ^1.3 μY / cm 2 (?).

[0139] (Results and discussion)

In Example 2-1 to Example 2-3, leakage current and electric capacity substantially the same as those in Example 1 were obtained. In addition, it was confirmed that Example 2 gave much better results than Example 1 (that is, leakage current was small and electric capacity was large). For this reason, in order to obtain a dielectric film with small leakage current and good performance, the silicon substrate 91 is rotated at a rotational speed of 2000 rpm or more for 20 seconds or more in the spin drying process after the side rinse process. I can understand that. In Example 2, since the leakage current was smaller and the electric capacity was larger than in Examples 2-1 to 2-3, the rotation speed and rotation time of the silicon substrate 91 were set to 5000 rpm and 60 seconds, respectively. Then, it can be estimated that the excess solvent R remaining on the peripheral edge of the wafer W is sufficiently volatilized.

[0140] The dielectric film according to the present invention is composed of strontium titanate, calcium titanate, barium zirconate, etc. in addition to barium titanate as long as it is a dielectric film having an ABOx type perovskite crystal structure. May be.

[0141] Regarding this application, Japanese Patent Application No. 2005-2 43286 filed on August 24, 2005, Japanese Patent Application No. 2006- 221998, filed August 16, 2006 Claim the priority based on No. and incorporate all the contents of the basic application into this application. Industrial applicability

When the dielectric film having an ABOx type perovskite crystal structure according to the present invention is used for a capacitor, generation of a leakage current can be suppressed as much as possible while securing a desired electric capacity. Therefore, it is expected to be applied to capacitors mounted on circuits that require more stability, such as power supply circuits for CPUs.

Claims

The scope of the claims

[1] The first dielectric thin film having an ABOx-type mouth bumite crystal structure, and the second dielectric thin film having the ABOx-type mouth-bushite crystal structure formed on the first dielectric thin film. An electrical membrane,

In the first dielectric thin film, the average particle size of the crystal particles constituting the second dielectric thin film is smaller than the average particle size of the crystal particles constituting the first dielectric thin film. 2 in the boundary region with the dielectric thin film, the crystal grains constituting the first dielectric thin film and the crystal grains constituting the second dielectric thin film are mixed.

A dielectric film having an ABOx-type bebbitite crystal structure.

[2] The density of the boundary region between the first dielectric thin film and the second dielectric thin film is the density of the other region of the first dielectric thin film and the density of the second dielectric thin film. 2. The dielectric film having an ABOx type perovskite crystal structure according to claim 1, wherein the dielectric film is higher.

[3] A capacitor using a dielectric film having an ABOx type perovskite crystal structure, wherein a pair of electrodes are formed on a pair of main surfaces of the dielectric film according to [1].

[4] A method for forming a dielectric film having an ABOx type perovskite structure composed of a laminated film of films having an ABOx type perovskite structure.

Providing a first dielectric thin film having an ABOx-type bottom bumskite crystal structure including voids having an average diameter not less than a predetermined value;

A dielectric composition forming liquid containing particles having an ABOx type bottom bumskite crystal structure having an average particle size smaller than the average diameter of the voids and a predetermined organic solvent is applied onto the first dielectric thin film. An application process to

Firing the resultant product obtained in the coating step to form a second dielectric thin film having an ABOx type bevbskite crystal structure on the first dielectric thin film; and

A method for forming a dielectric film having an ABOx-type mouth-bumskite structure.

[5] The dielectric-forming composition liquid for forming the second dielectric thin film comprises a metal species A selected from the group consisting of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides. 5. The method for forming a dielectric film having an ABO X-type bevacuskite structure according to claim 4, comprising one or more compounds including metal species B.

6. The ABOx type according to claim 5, wherein the concentration of the metal species A is 0.1 to 0.7 mmolZg, and the concentration of the metal species B is 0.1 to 0.7 mmolZg. Perovskite A method for forming a dielectric film having a crystal structure.

[7] The metal species A includes one or more metals selected from lithium, sodium, calcium, strontium, norlium, and lanthanum, and the metal species B includes one or more metals selected from titanium, zirconium, tantalum, and niobium. 6. The method for forming a dielectric film having an ABO X-type bottom bumskite crystal structure according to claim 5, comprising:

[8] The organic solvent contained in the dielectric composition liquid for forming the second dielectric thin film is a kind selected from the group consisting of alcohol solvents, ether solvents, ketone solvents, and ester solvents. 5. The method of forming a dielectric film having an ABO X-type bebskite crystal structure according to claim 4, comprising the organic solvent described above.

[9] The step of preparing the first dielectric thin film includes:

Having an ABOx type perovskite crystal structure having an average particle size larger than an average particle size of particles having an ABOx type bebskite crystal structure contained in the dielectric forming composition liquid for forming the second dielectric thin film A first dielectric thin film forming coating step of applying a dielectric-forming composition liquid containing particles on the surface of the substrate;

Firing the resultant obtained in the coating step to form a first dielectric thin film having an ABOx type perovskite crystal structure on the substrate;

The method for forming an insulator film having an ABOx-type perovskite structure according to claim 4, comprising:

[10] The first dielectric thin film forming coating step includes a step of rotating the substrate to extend the dielectric forming composition liquid for forming the first dielectric thin film on the substrate. After the first extension step, after the first extension step, a solvent is applied to the surface side peripheral portion of the substrate, and the surface side peripheral portion of the substrate is cleaned, and after the first cleaning step, The substrate is rotated at a predetermined rotation speed for a predetermined time to dry the surface side peripheral portion of the substrate. And a drying process of

The coating process for forming the second dielectric thin film includes a second extending process of rotating the substrate and extending the dielectric forming composition liquid for forming the second dielectric thin film on the substrate. After the second extension step, a solvent is applied to the surface side peripheral portion of the substrate, and the surface side peripheral portion of the substrate is cleaned, and after the second cleaning step, the substrate is removed. A second drying step of rotating the surface side peripheral portion of the substrate by rotating at a predetermined rotation speed for a predetermined time,

10. The method for forming a dielectric film having an ABOx type perovskite structure according to claim 9.

[11] The dielectric forming composition liquid for forming the first dielectric thin film is an ABOx type obtained by hydrolyzing the dielectric forming composition liquid for forming the second dielectric thin film. 10. The method for forming a dielectric film having an ABOx type perovskite crystal structure according to claim 9, comprising particles having a crystal structure and an average particle diameter of lOOnm or less.

[12] In a system for forming a dielectric film having an ABOx type perovskite structure composed of a laminated film of films having an ABOx type perovskite structure,

On the first dielectric thin film having an ABOx type bottom bumskite crystal structure containing voids whose average diameter is not less than a predetermined value, the average diameter of the ABOx type perovskite crystal structure is smaller than the average diameter of the voids. A coating device for applying a dielectric forming composition liquid containing particles having a particle; and a resultant obtained by applying the dielectric forming composition liquid by the coating device to sinter the first dielectric thin film. A firing apparatus for forming a second dielectric thin film having an ABOx-type bottom buxite crystal structure thereon;

A system for forming a dielectric film having an ABOx type mouth bumskite structure.

[13] The dielectric forming composition liquid for forming the second dielectric thin film includes a metal species A and a metal species B selected from the group consisting of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides. 13. The system for forming a dielectric film having an AB Ox type perovskite structure according to claim 12, comprising at least one compound.

[14] The concentration of the metal species A is 0.1 to 0.7 mmol Zg, and the concentration of the metal species B is 0.1. 14. The system for forming a dielectric film having an ABOx type perovskite crystal structure according to claim 13, wherein the dielectric film has a structure of ˜0.7 mmol / g.

The metal species A includes one or more metals selected from lithium, sodium, calcium, strontium, barium, and lanthanum, and the metal species B includes one or more metals selected from titanium, zirconium, tantalum, and tube. 14. The system for forming a dielectric film having an AB Ox type perovskite crystal structure according to claim 13.