WO2007032193A1

WO2007032193A1 - METHOD FOR MANUFACTURE OF DIELECTRIC FILM HAVING ABOx TYPE of PEROVSKITE-TYPE CRYSTALLINE STRUCTURE

Info

Publication number: WO2007032193A1
Application number: PCT/JP2006/316630
Authority: WO
Inventors: Katsuya Okumura; Takahiro Kitano; Yoshiki Yamanishi; Muneo Harada; Tatsuzo Kawaguchi; Yoshihiro Hirota
Original assignee: Tokyo Electron Limited; Octec Inc.
Priority date: 2005-08-24
Filing date: 2006-08-24
Publication date: 2007-03-22
Also published as: JP2007055846A; TW200714366A

Abstract

A constituent solution for formation of a dielectric body is applied onto a first thin film (31) and then heated/fired, wherein the first thin film (31) has an ABOx type of perovskite-type crystalline structure and contains voids (42) having an average diameter equal to or larger than a predetermined value and the constituent solution contains particles each of which has an ABOx type of perovskite-type crystalline structure and which has an average particle diameter smaller than the average diameter of the voids (42). As a result, a second thin film (32) having an ABOx type of perovskite-type crystalline structure. In this manner, a dielectric film having an ABOx type of perovskite-type structure and composed of a laminate of films each having an ABOx type of perovskite-type structure can be manufactured. The boundary area between the first thin film (31) and the second thin film (32) in the dielectric film becomes dense, since a part of the constituent solution is incorporated into the voids (42) during the application of the constituent solution.

Description

Specification

Method and system for forming dielectric film having ABOx type perovskite crystal structure

Technical field

The present invention relates to a method and 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 has an ABOx-type perovskite crystal structure that can reduce leakage current. Therefore, it is desired to establish a new method and system for forming a dielectric film.

Means for solving the problem

[0006] In order to solve the above problems, the method for forming a dielectric film having an ABOx type perovskite crystal structure according to the present invention includes an ABOx type perovskite crystal including voids having an average diameter of a predetermined value or more. A first dielectric thin film having a structure, a particle having an ABOx-type perovskite crystal structure having an average particle diameter smaller than the average diameter of the voids, and a predetermined solvent; An application process for applying the composition liquid onto the first dielectric thin film, and a resultant product obtained by the application process are baked to form an ABOx-type perovskite crystal structure on the first dielectric thin film. And a firing step for forming the second dielectric thin film.

[0007] Prior to the applying step, a step of applying a predetermined solvent to the surface of the first dielectric thin film and replacing the air in the gap with the predetermined solvent may be further provided.

[0008] The application step may include a step of supplying the dielectric forming composition liquid until a liquid deposit is formed on the first dielectric thin film. In this case, the coating step may further include a step of widening the liquid accumulation portion by rotating the first dielectric thin film.

[0009] Prior to the firing step, an air permeation step may be further included in which air in the gap is sucked and a part of the dielectric forming liquid is infiltrated into the gap.

[0010] In the permeation step, the resultant product obtained in the coating step is placed in a sealed space, and a predetermined pressure (for example, volatilization of the predetermined solvent contained in the dielectric forming composition liquid) is placed in the sealed space. May be provided with a depressurizing step of depressurizing to a pressure equal to or lower than

[0011] Further, in the permeation step, the result obtained in the application step is placed in a sealed space, and the inside of the sealed space is decompressed to a first pressure, and the inside of the sealed space is reduced. A step of increasing pressure from the first pressure to a predetermined pressure, and a second pressure lower than the predetermined pressure force and the first pressure in the sealed space (for example, the dielectric composition-containing composition liquid includes And a second pressure reducing step for reducing the pressure to a level equal to or lower than a pressure at which volatilization of the predetermined solvent is started.

[0012] The first dielectric thin film is formed of the dielectric forming set for forming the second dielectric thin film. Apply a composition liquid for dielectric formation containing particles with ABOx-type perovskite crystal structure with an average particle size larger than the average particle size of particles with ABOx-type perovskite crystal structure contained in the composition to the surface of the substrate A first dielectric thin film having an ABOx type perovskite crystal structure is formed on the substrate by firing a coating process for forming the first dielectric thin film and firing the resultant product obtained in the coating process. The first dielectric thin film is fired for the first dielectric thin film to be formed.

[0013] The base material in this case corresponds to a semiconductor substrate, an electrode formed on the semiconductor substrate, a dielectric thin film, and the like.

[0014] 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. It may be configured to include one or more compounds and a predetermined solvent!

[0015] In this case, the metal species A includes one or more metals selected from lithium, sodium, calcium, strontium, normium and lanthanum, and the metal species B is one of titanium, zirconium, tantalum and niobium. You may make it the structure containing the above metals.

[0016] The dielectric forming composition liquid for forming the first dielectric thin film is obtained by hydrolyzing the dielectric forming composition liquid for forming the second dielectric thin film. May be configured to include particles having an average particle size of lOOnm or less having an integer of 1 or more type crystal structure.

[0017] Further, the dielectric film formation system having an ABOx type perovskite crystal structure of the present invention is provided 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 applying a dielectric 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 a predetermined solvent; and the dielectric by the coating apparatus A firing apparatus for firing the resulting product obtained by applying the body-forming composition liquid to form a second dielectric thin film having an ABOx-type bechbskite crystal structure on the first dielectric thin film; It is characterized by providing.

[0018] The coating apparatus may include a solvent coating unit that coats only the predetermined solvent contained in the dielectric forming composition liquid for forming the second dielectric thin film.

[0019] Air in the gap is sucked, and the induction for forming the second dielectric thin film in the gap is performed. You may further provide the osmosis | permeation apparatus which osmose | permeates a part of composition liquid for electric body formation.

[0020] The permeation device includes a sealed container that contains a resultant product obtained by applying the dielectric forming composition liquid for forming the second dielectric thin film by the coating device, and an inside of the sealed container. A depressurization means for depressurizing to a predetermined pressure (for example, a pressure at which volatilization of the predetermined solvent contained in the dielectric-forming composition liquid for forming the second dielectric thin film is started) or less. Good.

[0021] Further, the permeation device includes a sealed container for accommodating a resultant product obtained by applying the dielectric forming composition liquid for forming the second dielectric thin film by the coating device, and the sealed container. A first pressure reducing means for reducing the pressure in the sealed container to a first pressure, a pressure increasing means for increasing the pressure in the sealed container from the first pressure to a predetermined pressure, and the first pressure in the sealed container from the predetermined pressure. A second pressure that is reduced to below a second pressure lower than the pressure (for example, a pressure at which the volatilization of the predetermined solvent contained in the dielectric forming liquid for forming the second dielectric thin film is started). And a decompression unit.

The invention's effect

[0022] According to the present invention as described above, it is possible to form a dielectric film having an ABOx type bottom bumskite crystal structure having a dense surface and a small leakage current even if it is a thin film. .

Brief Description of Drawings

[0023] FIG. 1 is a cross-sectional view showing an example of a capacitor using a dielectric film having an ABOx-type bottom bumskite crystal structure according to the present invention.

FIG. 2 is a cross-sectional view for explaining a step of forming a first coating film.

FIG. 3 is a cross-sectional view for explaining a heating / firing step for forming a first thin film.

FIG. 4 is a schematic view showing a state of modification of the dielectric film in the heating and firing process for forming the first thin film.

FIG. 5 is a cross-sectional view for explaining the coating film forming process and the process up to the manufacture of the capacitor.

FIG. 6 is a cross-sectional view for explaining the action of a dielectric film having an ABOx-type bottom buxite crystal structure. FIG. 7 is a diagram showing a schematic configuration of a coating unit used in the first embodiment of the coating film forming step, where (a) is a sectional view of the coating unit and (b) is a plan view thereof.

圆 8] A schematic diagram for explaining the first embodiment of the coating film forming step.

9] A cross-sectional view for explaining the operation of the first embodiment of the coating film forming step. FIG. 10 is a schematic diagram for explaining a second embodiment of the coating film forming step.

圆 11] It is a cross-sectional view for explaining the operation of the second embodiment of the coating film forming step. 12] A diagram showing a schematic configuration of a coating unit used in the third embodiment and the fourth embodiment of the coating film forming step, (a) is a sectional view of the coating unit, and (b) is a sectional view of the coating unit. FIG.

FIG. 13 is a perspective view showing a state of application of the application liquid performed by the application unit shown in FIG.

14] A cross-sectional view showing a schematic configuration of a reduced-pressure drying unit used in the third and fourth embodiments of the coating film forming step.

FIG. 15 is a schematic diagram for explaining the third embodiment of the coating film forming step.

FIG. 16 is a characteristic diagram showing the change over time in the pressure of the sealed container provided in the vacuum drying unit. FIG. 17 is a cross-sectional view for explaining the operation of the third embodiment of the coating film forming step.圆 18] A schematic view for explaining a fourth embodiment of the coating film forming step.

FIG. 19 is a cross-sectional view for explaining the operation of the fourth embodiment of the coating film forming step. FIG. 20 is a plan view showing a dielectric film forming apparatus included in a dielectric film forming system having an ABOx-type mouthbushite crystal structure according to an embodiment of the present invention.

FIG. 21 is a perspective view of a dielectric film forming apparatus according to the embodiment.

FIG. 22 is a cross-sectional view showing a schematic configuration of a heating unit provided in the dielectric film forming apparatus according to the embodiment.

FIG. 23 is a cross-sectional view showing a schematic configuration of a heating furnace provided in the dielectric film formation system according to the embodiment.

24] A perspective view for explaining a measurement sample used in an experiment conducted for confirming the effect of the present invention.

Explanation of symbols 1 Lower electrode

2 Upper electrode

3 Board

5, 51 Spin chuck 6, 56, 63 Coating liquid nozzles a, 3b, 3c Dielectric film 1 First thin film

1a 1st coating film 2 2nd thin film

2a Second coating film 0 Crystal grains

1 solvent

2 Air gap

4 Air

5 thinner

6 Second coating liquid I Carrier station 2 Processing section

, 6 Dispensing unit 2 cup body

7 Solvent nozzle

1 Wafer holder

Vacuum drying unit 0 Airtight container

5 Vacuum pump

Heating unit 1 Cooling plate 2 Hot plate 10 Heating furnace

101 wafer boat

104 Heating means

W Semiconductor wafer

BEST MODE FOR CARRYING OUT THE INVENTION

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

[0026] First, an example of a dielectric film having an ABOx type mouth-bushite 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. 1 (a) 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 3a.

[0027] The dielectric film 3a is a dielectric film having an ABOx type bottom bumskite 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. 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.

[0028] The first thin film 31 is a dielectric thin film having an ABOx type perovskite crystal structure including voids having an average diameter of 10 nm 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).

[0029] 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.

[0030] Metal species A includes Li (lithium), Na (sodium), Ca (calcium), Sr (strontium), One or more metals selected from 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. 1 (b) and FIG. 1 (c) 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 3b configured such that the first thin film 31 is sandwiched between two second thin films 32. In addition, the capacitor shown in FIG. 1 (c) includes a dielectric film 3c configured such that the second thin film 32 is sandwiched between the two first thin films 31.

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

Three

[0033] First, a method of forming the first thin film 31 on the surface of the lower electrode 21 (for example, made of Pt) formed on the substrate 23 which is a silicon substrate will be described. As described above, the first thin film 31 can be generated by applying the first coating liquid to the substrate 23 and heating and baking. The first coating liquid used in the present embodiment is a dielectric forming composition liquid containing an organic solvent and particles having an ABOx type perovskite crystal structure and an average particle diameter of 10 Onm or less.

[0034] 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.

[0035] (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.

[0036] The compound is selected from the group of metal alkoxides, metal carboxylates, metal complexes, and metal hydroxides.

[0037] Metal species A is one or more metals selected from the internal forces of Li, Na, Ca, Sr, Ba, and La. Is preferred. 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.

[0038] The concentration of the metal species A in the solution during dissolution is 0.1 to 0.7 mmol Zg. Similarly, the concentration of metal species B is also 0.1 to 0.7 mmol Zg.

[0039] Examples of the metal alkoxide include, for example, barium alkoxides such as dimethoxybarium, diethoxybarium, dipropoxybarium, diisopropoxybarium, dibutoxybarium, and diisobutoxybarium, dimethoxystrontium, cetoxystrontium, dioxy Use strontium alkoxides such as propoxystrontium, diisopropoxystrontium, dibutoxystrontium, diisobutoxystrontium, tetramethoxytitanium, tetraethoxytitanium, tetrapropoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, tetraisobutoxytitanium, etc. Can do.

[0040] 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.

[0041] Examples of the metal complex include titanium arylacetoacetate triisopropylate, 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.

[0042] The metal hydroxide is a compound in which a hydroxide ion is coordinated to a metal atom. It is represented by general formula (1).

[0043] M ^a (OH) · χΗ Ο · · · Formula (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. [0044] As the organic solvent, for example, alcohol solvents, polyhydric alcohol solvents, ether solvents, ketone solvents, ester solvents and the like can be used.

[0045] As the alcohol solvent, methanol, ethanol, propanol, butanol, amyl alcohol, cyclohexanol, methylcyclohexanol, and the like can be used.

[0046] Examples of the polyhydric alcohol solvent include ethylene glycol monomethyl ether, ethylenic glycolenomonoacetate ester, diethylene glycolenol monomethylenether, jetylene glycolenol monoacetate, propylene glycol monoethyl ether, propylene glycol. Nole monoacetate, dipropylene glycol monoethanolo ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, methoxybutanol, propylene glycol monoethylenoate ethere acetate, propylene glycol monomethyl ether acetate, di Propylene glycol propyl ether, dipropylene glycol monobutyl ether and the like can be used.

[0047] 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.

[0048] 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.

[0049] Examples of the ester solvent include ethyl formate, methyl acetate, ethyl acetate, butyl acetate, cyclohexyl acetate, methyl propionate, ethyl butyrate, ethyl oxyisobutyrate, ethyl acetoacetate, ethyl acetate, methoxybutyl acetate, Jetyl oxalate, jetyl malonate and the like can be used. [0050] The organic solvent may be one of the above solvents or 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.

[0052] (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.

[0053] 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.

[0054] 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 (more preferably 20 to 100 times the molar amount). When water is added in such a molar amount, the crystallinity of the particles is improved and the dispersibility is also improved.

[0055] In addition to adding only water to the solution, a mixture of one or more solvents selected from the plurality of solvents described above and water may be added.

[0056] 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.

[0057] Hydrolysis condensate produced after addition of water is usually 0.5 to 10 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.

[0058] By passing through the above dissolution step and 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.

[0059] (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.

[0060] Examples of the organic solvent used in this case include alcohol solvents, polyhydric alcohol solvents, ether solvents, ketone solvents, and ester solvents. As these organic solvents, those exemplified in the section of the dissolution step can be used.

[0061] (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.

[0062] As a method of 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.

[0063] Examples of the organic solvent used for dispersion include alcohol solvents, polyhydric alcohol solvents, ether solvents, ketone solvents, ester solvents, and the like. Further, the organic solvent used for dispersion may be the same as or different from the organic solvent used in the purification step.

[0064] 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. ).

[0065] 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 char-on surfactant, Cationic surfactants may be used as dispersants!

[0066] As such a surfactant, for example, polyoxyethylene polyoxypropylene It is possible to use glycols, polyoxypropylenes of ethylenediamine, polyoxyethylene condensates (pull-mouth type), sodium alkylbenzene sulfonate, polyethyleneimine, polyvinylpyrrolidone, oligomers containing perfluoroalkyl groups, etc. it can.

[0067] The type and amount of the dispersant 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 0.001 with respect to the crystal particle lOOg.

˜10 g is preferred.

[0068] 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) is obtained. A certain first coating solution can be obtained.

Next, a process for applying the first coating liquid obtained as described above to the substrate 23 will be described. This process is performed in a coating unit (described later).

First, as shown in FIG. 2 (a), a substantially central portion on the back surface side of the substrate 23 having the lower electrode 21 formed on the surface is held by a 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.

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)).

[0072] Thereafter, the substrate 23 is rotated at a predetermined rotation speed (eg, 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)).

[0073] 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.

[0074] Next, a method for forming the first thin film 31 by heating the first coating film 31a formed as described above will be described.

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 (eg, 250 ° C.). Heat for 1 minute ( Beta processing). The organic solvent contained in the first coating film 31a is volatilized by the beta treatment, which is a pretreatment for baking. In addition, hydrolysis occurs and the coating film becomes gelled, and further, a condensation polymerization force S 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 organic solvent volatilizes, agglomeration of crystal particles occurs due to the action of the binder in the coating film, and the crystal particles become large.

[0076] Subsequently, as shown in FIG. 3B, the first coating film 31a formed on the surface of the lower electrode 21 on the substrate 23 is heated to a predetermined temperature by using a baking apparatus described later. (For example, 800 ° C) Heat for 60 minutes (firing process). Due to this baking treatment, the inside of the first coating film 31a is changed to an amorphous state force crystallization state. As a result, as shown in FIG. 4 (c), a first thin film 31 made of a barium titanate film having an ABO X-type bottom buxite crystal structure is formed.

. This ABOx-type perovskite crystal structure has an ABOx X value in the range of 2.5 to 3.5 depending on the oxygen supersaturation or deficiency.

[0077] The first thin film 31 thus formed 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.

[0079] First, the second coating liquid is applied to the surface of the first thin film 31 (application process), and as shown in FIG. 5 (a), the second coating film 32a is formed (coating film formation). Process). The present invention is characterized by the method for forming the coating film 32a. This feature will be described in detail later.

[0080] The second coating liquid which is the dielectric forming composition liquid is generated in the manufacturing process of the first coating liquid (more specifically, the above-described dissolution step). If the concentration of the first coating solution is too high, the first coating solution will not enter the gap of the first thin film 31 as will be described later. Therefore, 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 also 0.1 to 0.7 mmol / g. In addition, as the organic solvent, the alcohol-based solvent, ether-based solvent, ketone-based solvent, ester-based solvent described above having good wettability with respect to the first thin film 31. The use of a rutile solvent or the like further increases the degree of penetration.

Next, in the heating unit described later, as shown in FIG. 5 (b), the second coating film 32a formed on the surface of the first thin film 31 is subjected to a predetermined temperature (eg, 250 ° C.). ) For 1 minute (heat treatment). The organic solvent contained in the second coating film 32a is volatilized by the heat treatment before firing (that is, beta treatment) (heating step). In addition, hydrolysis occurs, the coating film gels, and condensation polymerization occurs. As a result, a network structure of barium titanate that forms a precursor film of norium titanate having an ABOx type perovskite crystal structure is formed.

Subsequently, as shown in FIG. 5 (c), 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. Heat for 60 minutes (firing process). As a result of 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 bobsite crystal structure is formed. This ABOx-type perovskite crystal structure has an ABOx X value in the range of 2.5 to 3.5 depending on the oxygen supersaturation or deficiency.

[0083] The second thin film 32 thus formed 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 lOnm 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).

[0084] 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, the dielectric film 3a (see FIG. 1 (a)) having the ABOx type perovskite crystal structure is formed.

Here, when the electrode (upper electrode 22) is formed on the upper surface of the dielectric film 3a, the capacitor shown in FIG. 1 (a) is obtained. Specifically, as shown in FIG. 5 (d), the upper electrode 22 can be formed by sputtering the upper side force of the second thin film 32 with, for example, A1 in a sputtering apparatus (not shown) (FIG. 5 (e)). )reference).

[0087] As described above, the ABOx-type perovskite crystal structure according to this embodiment of the present invention According to the method of forming a dielectric film having the following, the following excellent actions and effects can be obtained.

(1) The first coating solution is a special solution obtained by hydrolyzing and dispersing the second coating solution. As described above, the first coating solution 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.

[0089] Further, 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 laminated one by one. Thus, the dielectric film 3a 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 3a 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. 6 (a), the average diameter of the voids 42 formed between the crystal grains 40 in the first thin film 31 is not less than lOnm. Therefore, the surface of the first thin film 31 is uneven due to the presence of voids in the porous structure, and both the crystal grains 40 and the voids 42 are large, and thus the flatness is poor.

[0091] 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. 6 (b), in the step of applying the second coating liquid to the surface of the first thin film 31, it is generated in the surface side region of the first thin film 31. The particles 43 constituting the second coating liquid enter the voids 42 that open, and penetrate into the interior. As a result, as shown in FIG. 6C, 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 voids 42 of the first thin film 31 are 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.

[0092] Actually, 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 void 42 of the first thin film 31 It was observed that the second coating solution entered the

[0093] As described above, since the void 42 formed on the surface of the first thin film 31 is blocked by the particles 43 constituting the second coating liquid, the flatness of the surface of the first thin film 31 is improved. improves. In addition, since the second thin film 32 is formed on the surface of the first thin film 31 with good flatness, the flatness of the surface of the second thin film 32 is also improved.

[0094] Further, 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.

[0096] In addition, the second reason is that a dense layer (a layer having a high density) is formed at the boundary between the first thin film 31 and the second thin film 32, so that the Pt particles of the lower electrode 21 Even if it penetrates from the lower side of the first thin film 31 due to thermal diffusion, it exceeds the boundary between the first thin film 31 and the second thin film 32. Therefore, it is difficult to penetrate into 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 conductive path of the dielectric film 3a having the ABOx type bevskite crystal structure composed of the first thin film 31 and the second thin film 32 can be suppressed. The generation of current can be suppressed.

Note that the capacitors having the structures shown in FIGS. 1 (b) and 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. A dielectric film 3b or a dielectric film 3c having an orbskite 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 3b 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 is flattened. In the case of the capacitor having the structure shown in FIG. 1 (c), the first thin film 31 located on the first layer (on the lower electrode 21 side) of the dielectric film 3c 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 preferred example of the coating film forming process for forming the second coating film 32a will be described. As described above, the dielectric film according to the present invention forms the second thin film 32 on the surface of the first thin film 31, so that the void 42 of the first thin film 31 constitutes the second thin film 32. It is characterized by being filled with crystal grains. By the way, since the coating solution of the second thin film 32 (that is, the second coating solution) has a high viscosity, when the second coating solution is applied directly onto the first thin film 31 by spin coating, It is difficult to penetrate into the gap 42 of the first thin film 31. This is because the gap 42 is filled with a gas such as air before application of the second coating liquid, and this gas inhibits the entry of the particles 43 constituting the second coating liquid. It is assumed that there is. In the coating film forming step of the dielectric film forming method according to the present invention, this point is improved, and by using the method, the second coating liquid penetrates into the voids 42 of the first thin film 31. It becomes easy. Hereinafter, this point will be described in detail. [0099] [First embodiment of coating film forming step]

First, a first embodiment of the coating film forming process will be described with reference to FIGS. FIG. 7 is a schematic configuration diagram of the coating unit 5 which is a coating apparatus for performing this process. In the coating unit 5 shown in FIG. 7, reference numeral 51 denotes a spin chuck for sucking and sucking and holding the central portion of the back side of a semiconductor wafer (hereinafter referred to as “wafer”) W as a substrate. The spin chuck 51 is configured to be rotatable and vertically movable about a vertical axis. On the outer periphery of the wafer W held by the spin chuck 51, there is provided a cup body 52 that opens on the upper side so as to surround the wafer W. On the bottom side of the cup body 52, a recess-shaped liquid receiving portion 53 is provided on the lower peripheral side of the wafer W over the entire circumference. Reference numeral 54a denotes a drainage path for discharging the drain of the second coating liquid and the like, and 54b denotes an exhaust path.

Reference numeral 56 denotes a coating liquid nozzle that supplies the second coating liquid to the wafer W held on the spin chuck 51. Reference numeral 57 denotes a solvent nozzle (solvent application means) for supplying an organic solvent (for example, thinner one liquid) contained in the second application liquid. Reference numeral 55 denotes a nozzle unit in which a coating liquid nozzle 56 and a solvent nozzle 57 are integrally provided. The nozzle unit 55 can be moved up and down by an elevating mechanism 58a, and can be moved in the X direction by a moving mechanism 58c along a guide rail 58b extending in the X direction. As a result, the nozzle unit 55 supplies the second coating liquid or thinner liquid to the wafer W (the position shown in FIG. 7 (a)) and the standby position outside the cup body 52 (FIG. 7 ( It is possible to move between the positions shown in b).

Further, the coating liquid nozzle 56 is connected to a second coating liquid supply source 56b via a coating liquid supply path 56a provided with a valve VI. Further, the solvent nozzle 57 is connected to a supply source 57b of an organic solvent (a thinner liquid in this embodiment) via a solvent supply path 57a provided with a valve V2. The application unit 5 of the present embodiment applies the second application liquid by spin coating, but the first application liquid of the first thin film 31 described above can also be applied using the apparatus.

[0102] Next, the second coating film forming process performed in the coating unit 5 will be described. First, the spin chuck 51 is positioned above the cup body 52. And illustrated However, the wafer w transported by the transport means is placed on the spin chuck 51 by a cooperative action with the lifting pins, not shown. Next, the spin chuck 51 is lowered to the processing position shown in FIG. Here, it is assumed that the first thin film 31 is formed on the wafer W on the wafer W transferred to the coating unit 5.

Next, as shown in FIG. 8 (a), the nozzle unit 55 is moved so that the discharge port at the tip of the solvent nozzle 57 faces the substantially center of the wafer W held by the spin chuck 51. Then, the thinner one liquid 45 is supplied from the solvent nozzle 57 to the approximate center of the wafer W without rotating the wafer W. In this way, the thinner liquid 45 gradually spreads concentrically toward the peripheral edge side of the substantially central force of the wafer W, and is applied to the entire surface of the wafer W.

Next, as shown in FIG. 8B, the nozzle unit 55 is moved so that the discharge port at the tip of the coating liquid nozzle 56 faces the substantially center of the wafer W held by the spin chuck 51. Then, the second coating liquid 46 is supplied from the coating liquid nozzle 56 to the approximate center of the wafer W while the wafer W is rotated by the spin chuck 51 at a rotational speed of about 100 to 1000 rpm, for example. In this way, the second coating liquid 46 is applied to the entire surface of the wafer W by the substantially central force of the wafer W extending toward the peripheral side due to the centrifugal force of the rotation of the wafer W. Become.

Next, as shown in FIG. 8C, the wafer W is rotated at a rotational speed of, for example, about 1500 rpm, and the excess second coating liquid 46 is shaken off. Thereafter, as shown in FIG. 8 (d), the second coating liquid 46 is dried by rotating the wafer W at a rotational speed of about 2000 rpm, for example. As described above, the second coating film 32a having a thickness of, for example, 180 nm is formed on the surface of the first thin film 31 on the wafer W (see FIG. 5A). In this state, most of the particles of the compound containing Ba and the compound containing Ti in the second coating film 32a are dispersed in the solvent, and a part of the particles is barium titanate. It is inferred that

[0106] After performing the above-described coating film forming step, the second thin film 32 is formed by successively performing the heating step and the baking step, which are the pretreatments of the baking described above.

When the coating film forming step according to the first embodiment described above is performed, an effect that the second coating liquid 46 easily enters the gap 42 of the first thin film 31 is obtained. The reason for this is as follows. And explain. As shown in FIG. 9 (a), before applying the thinner liquid 45, the air 44 is in the gap 42 of the first thin film 31. By the way, since thinner liquid 45 is 2-methoxyethanol, it has the property of being easily replaced with air. Accordingly, when the thinner liquid 45 is applied to the surface of the first thin film 31 in the above-described state, the thinner liquid 45 becomes air 44 that has entered the gap 42 of the first thin film 31 as shown in FIG. 9 (b). Is replaced with As a result, the gap 42 of the first thin film 31 is filled with the thinner liquid 45.

[0108] Further, the above replaceability is improved by not rotating the wafer W during the supply of the thinner liquid 45. That is, in the non-rotating state, the substantially central force of the wafer W is also directed toward the peripheral side, and a liquid flow of the thinner liquid 45 is generated. As a result, the thinner liquid is entirely applied to the first thin film 31 on the wafer W. 45 will be applied. In other words, compared with the case where the thinner liquid 45 is applied while rotating the wafer W, the thinner liquid is applied while slowly penetrating. As a result, the substituting property between the air 44 in the gap 42 of the first thin film 31 and the thinner liquid 45 is enhanced. It is not always necessary to be in a non-rotating state. For example, if it is a low-speed rotation of 20 rpm or less, the same effect can be obtained and the time can be reduced.

Subsequently, the second coating liquid 46 is applied in the state where the thinner liquid 45 is present on the surface of the first thin film 31 as described above. Then, as shown in FIGS. 9 (c) and 9 (d), the thinner liquid 45 and the second coating liquid 46 are replaced in the gap 42 of the first thin film 31. In this case, since both are liquids, the replacement proceeds much faster than the replacement between the second coating liquid 46 and the air 44, that is, between the liquid and the gas.

[0110] For this reason, by applying a thinner liquid 45 to the surface of the first thin film 31, and applying the second coating liquid 46 before the thinner liquid 45 is volatilized, the voids in the first thin film 31 are obtained. 42 can be quickly filled with the second coating liquid 46.

[0111] As described above, when the coating film forming step according to the first embodiment is performed, the second coating liquid 46 can more easily permeate into the gap 42 of the first thin film 31, and the second force can be reduced. If the amount of the coating liquid 46 is reduced, the application time can be shortened. Therefore, a denser layer, that is, a layer having a higher density, is formed on the surface of the first thin film 31, and the flatness is improved. As described above, when the second thin film 32 is formed on the first thin film 31 having high flatness, as a result, the flatness of the surface of the dielectric film 3a having the ABOx-type perovskite crystal structure is improved. [0112] Further, when the capacitor is generated by forming the lower electrode 21 and the upper electrode 22 on both surfaces of the dielectric film 3a (see Fig. 1 (a)), the generation of leakage current is further suppressed. be able to . This is because the formation of a highly dense (dense) film near the boundary between the first thin film 31 and the second thin film 32 makes it difficult to form a conductive path in the dielectric film 3a. Depending on the reason

[0113] [Second embodiment of coating film forming step]

Next, a second embodiment of the coating film forming process will be described. Note that the coating apparatus used in this process is the same as that of the first embodiment (coating unit 5 shown in FIG. 7). The description of the configuration will be omitted.

[0114] First, the spin chuck 51 is positioned above the cup body 52. Then, V (not shown) and the wafer W transferred by the transfer means are placed on the spin chuck 51 by a cooperative action with the lift pins (not shown). Next, the spin chuck 51 is lowered to the processing position shown in FIG. Here, it is assumed that the first thin film 31 is formed on the wafer W on the wafer W transferred to the coating unit 5.

Next, as shown in FIG. 10 (a), the nozzle unit 55 is moved so that the discharge port at the tip of the coating liquid nozzle 56 faces the substantially center of the wafer W held by the spin chuck 51. Then, the second coating liquid 46 is supplied from the coating liquid nozzle 56 to the approximate center of the wafer W without rotating the spin chuck 51 or rotating at a low speed of 10 rpm or less. This supply is continued until the second coating liquid 46 reaches the peripheral edge on the wafer W. By supplying the second coating liquid 46 in this manner, the substantially central force of the wafer W of the second coating liquid 46 is also directed toward the peripheral side. Then, as shown in FIG. 10 (b), when the second coating solution 46 reaches the peripheral edge on the wafer W, a liquid coating portion of the second coating solution 46 is generated on the surface of the first thin film 31. To do. In this case, the thickness of the liquid deposit is, for example, about 2 m.

Next, as shown in FIG. 10C, the wafer W is rotated by the spin chuck 51 at a rotational speed of, for example, about 1500 rpm. The second coating liquid 46 spreads on the surface of the first thin film 31 by the centrifugal force due to this rotation, and is coated with an appropriate thickness. Also, the excess second coating liquid 46 is shaken off. After this, as shown in FIG. The second coating liquid 46 is dried by rotating at a rotational speed of about. As described above, the second coating film 32a (see FIG. 5A) having a thickness of, for example, 180 nm is formed on the surface of the first thin film 31 on the wafer W. In this state, most of the particles of the compound containing Ba and the compound containing Ti in the second coating film 32a are dispersed in the solvent, and a part of the particles is titanic acid. It is presumed that barium is produced.

[0117] After performing the above-described coating film forming step, the second thin film 32 is formed by successively performing the heating step and the baking step, which are the pretreatments of the baking described above.

When the coating film forming step according to the second embodiment described above is performed, an effect that the second coating liquid 46 easily enters the gap 42 of the first thin film 31 is obtained. The reason for this will be explained below. In the coating film forming step according to the second embodiment, the second coating liquid 46 is supplied without rotating the wafer _W or while rotating at a low speed, and the supply is performed by the second coating liquid 46. Continue until it reaches the entire surface of wafer W. Then, during this time, the liquid coating portion of the second coating liquid 46 is generated, and this prevents the volatilization of the thinner liquid 45 in the second coating liquid 46. Therefore, in the gap 42 of the first thin film 31, the second coating liquid 46 easily enters the gap 42 due to the presence of the thinner liquid 45 in the second coating liquid 46.

[0119] This point will be described in more detail. The liquid deposition of the second coating liquid 46 proceeds slowly with the substantially central force of the wafer W also directed toward the peripheral side. At that time, the thinner liquid 45 contained in the second coating liquid 46 extends to the peripheral side while volatilizing, so it can be said that it is easier to extend forward than the precursor component of the second coating liquid. . Further, as described above, the thinner liquid 45 is 2-methoxyethanol and can be easily replaced with air. For this reason, as shown in FIGS. 11 (a) and 11 (b), during the slow extension of the second coating solution 46, first, the thinner solution 45 in the second coating solution 46, Replacement with the air 44 in the air gap 42 occurs. Then, as shown in FIG. 11 (c), replacement of the thinner liquid 45 in the gap 42 with the remaining components of the second coating liquid 46 (ie, components other than the thinner liquid 45) is performed. As a result, it is presumed that the second coating liquid 46 can be quickly filled into the gap 42 of the first thin film 31.

On the other hand, in the spin coating in which the application of the second coating liquid 46 is performed while rotating the wafer W at a high speed, the second coating liquid 46 is applied so as to spread rapidly to the peripheral side of the wafer W. Therefore, it can be said that the thinner liquid 45 in the second coating liquid 46 is likely to volatilize. Also When the wafer W is rotated at a high speed of 2000 rpm, an air flow is generated by the rotation, and the thinner 45 is easily volatilized. Therefore, when the second coating solution 46 is extended, the thinner solution 45 is volatilized almost simultaneously. Accordingly, it is assumed that the thinner liquid 45 in the second coating liquid 46 cannot enter the gap 42, and as a result, the second coating liquid 46 hardly penetrates into the gap 42.

When the coating film forming step according to the second embodiment is performed as described above, the second coating liquid 46 is more easily penetrated into the gaps 42 of the first thin film 31, and the first thin film 31 A denser layer, that is, a layer having a higher density, is formed on the surface of the film, and the flatness is improved. Thus, when the second thin film 32 is formed on the first thin film 31 having high flatness, as a result, the flatness of the surface of the dielectric film 3a having the ABOx type bevskite crystal structure is improved.

[0122] Further, when the capacitor is formed by forming the lower electrode 21 and the upper electrode 22 on both surfaces of the dielectric film 3a (see Fig. 1 (a)), the generation of leakage current can be further suppressed. it can. This is because a denser (higher density) film is formed near the boundary between the first thin film 31 and the second thin film 32, thereby making it difficult to form a conductive path in the dielectric film 3a. Because

[Third Embodiment of Coating Film Forming Process]

Next, a third embodiment of the coating film forming process will be described. FIG. 12 is a schematic configuration diagram of the coating unit 6 which is a coating apparatus for carrying out this process. The coating unit 6 shown in FIG. 12 has a configuration in which the second coating liquid is applied in the manner of a single stroke!

[0124] In the coating unit 6 shown in Fig. 12, reference numeral 61 denotes a wafer holding unit for sucking and adsorbing the back side central portion of the wafer W and holding it horizontally. The wafer holding unit 61 is configured to be movable up and down by a lifting mechanism 61a. Reference numeral 60 denotes a case body, and a slit 62 extending in the X direction is formed in the top plate 60a of the case body 60. In the slit 62, a coating liquid nozzle 63 is provided so as to be movable in the X direction. Reference numeral 64a is a guide portion extending in the X direction. Reference numeral 64b denotes a ball screw portion. Reference numeral 64c is a moving body to which the coating liquid nozzle 63 is attached and screwed with the ball screw portion 64b. The coating solution nozzle 63 can move in the X direction via the moving body 64c by rotating the ball screw 64b by the motor M2. It has become so. The coating liquid nozzle 63 is connected to a second coating liquid supply source 63b via a supply path 63a having a valve V3.

[0125] The movable table 65c is configured to be movable in the Y direction while being guided by the guide portion 65b by a ball screw portion 65a driven by the motor Ml. With this configuration, the wafer holding unit 61 disposed on the moving table 65c can move intermittently in the Y direction. Reference numeral 66 denotes a mask that covers the peripheral area of the wafer W but opens the portion corresponding to the coating film forming area. The mask 66 is provided in order to prevent the second coating liquid from adhering to and wrapping around the peripheral area and back side of the wafer W.

[0126] Next, the second coating film forming process performed in the coating unit 6 configured as described above will be described. First, as shown in FIG. 13, for example, alignment is performed so that one end side of the wafer W in the Y direction is positioned directly below the coating solution nozzle 63. This positional force wafer holder 61 moves intermittently at a predetermined pitch in the Y direction toward the other end side of the wafer W in the Y direction. On the other hand, the coating solution nozzle 63 reciprocates in the X direction in accordance with the timing of intermittent movement of the wafer W. That is, the coating liquid nozzle 63 moves from one end side in the X direction to the other end side while discharging the coating liquid onto the wafer W while the wafer W is stationary. Then, after such reciprocation of the coating solution nozzle 63 once, the wafer W is moved in the Y direction by a predetermined amount (predetermined pitch) by the wafer holder 61. The coating solution nozzle 63 is folded back at the other end side in the X direction, and moves while discharging the coating solution onto the wafer W with a force toward one end side in the X direction. In this way, the second coating solution 46 is applied onto the wafer W in the manner of a single stroke.

Next, the reduced pressure drying unit 7 (penetration device) to which the wafer W is transferred after the coating process of the second coating liquid 46 is performed by the coating unit 6 will be described with reference to FIG. In FIG. 14, reference numeral 70 denotes a sealed container. Reference numeral 71 denotes a mounting table on which the wafer W is mounted. The mounting table 71 is provided with temperature adjusting means 72 for adjusting the temperature of the wafer W. Reference numeral 71 a is a protrusion for holding the back side of the wafer W. Reference numeral 73 denotes a lid, and reference numeral 74 denotes a lid lifting mechanism that lifts and lowers the lid 73. By the lid lifting / lowering mechanism 74, the lid 73 is raised when the wafer W is loaded / unloaded, and is lowered when vacuum drying is performed. When the lid 73 is lowered to the lowest point, the hermetic container 70 is configured by the lid 73 and the mounting table 71. Also, near the center of the ceiling of lid 73 The exhaust path 76 is connected. A vacuum pump 75 as a vacuum exhaust means is connected to the exhaust path 76 via a valve V4. A purge gas supply source 78 is connected to the exhaust passage 76 via a valve V5 and a supply passage 77.

Next, the reduced-pressure drying process (permeation process) performed by the reduced-pressure drying unit 7 configured as described above will be described. First, in a state where the lid 73 is positioned above, the wafer W is loaded onto the protrusion 71a by the cooperative action of a lift pin (not shown) and a transfer means. Next, the lid 73 is lowered and the sealed container 70 is closed. Next, the valve V4 is opened, the vacuum pump 75 is operated, the inside of the sealed container 70 is decompressed, and the wafer W is dried. After the wafer W is dried under reduced pressure in this way, the valve V4 is closed. Next, the valve V 5 is opened, and a purge gas (for example, N2) gas is caused to flow into the sealed container 70 to return the inside of the sealed container 70 to atmospheric pressure. Then, the lid 73 of the hermetic container 70 is raised and the wafer W is unloaded and transferred to the next process.

[0129] The second coating film forming process in the coating film forming step of the present embodiment is performed by the coating unit 6 and the reduced pressure drying unit 7 as follows. First, as shown in FIG. 15 (a), the coating unit 6 applies the second coating liquid 46 to the wafer W on which the first thin film 31 is formed as described above in the manner of one stroke. Next, the wafer W with the second coating liquid 46 applied on the surface of the first thin film 31 is transferred to the vacuum drying unit 7 and is placed on the mounting table 71 of the sealed container 70 as shown in FIG. Placed on. Then, under the condition of a temperature of 20 ° C., the valve V4 is opened and the vacuum pump 75 is operated to depressurize the sealed container 70 for a predetermined time (for example, about 3 minutes) (decompression step). As a result, the inside of the sealed container 70 is depressurized to a pressure lower than the pressure at which the solvent 45, which is a solvent, starts to be volatilized (for example, about lOOPa), as will be described later. Most of the thinner 45 in the coating 46 is volatilized.

Here, the change with time of the pressure in the sealed container 70 will be described with reference to FIG. 16 (a). First, when the pressure reduction in the sealed container 70 is started at time tl, the pressure in the sealed container 70 (substantially equal to the atmospheric pressure at the time tl) reaches the time t2 when the pressure becomes P1 (for example, a pressure of about lOOPa). It decreases rapidly. After reaching P1, the state remains constant until time t3, but decreases more rapidly after time t3. Here, Ueno, W The state of the first thin film 31 and the second coating liquid 46 on the surface will be described. First, when the pressure inside the sealed container 70 is also reduced, the air 44 entering the gap 42 of the first thin film 31 is gradually sucked from the gap 42 and removed. Then, when the pressure P1 (time tl) is reached, volatilization of the thinner liquid 45 as the solvent starts from the second coating liquid 46. This volatilization continues for a while while the pressure in the sealed container 70 is P1 (time t2 to time t3).

[0131] By performing vacuum drying on the second coating liquid 46 on the wafer W in this manner, the second coating film 32a having a thickness of, for example, 180 nm is formed on the surface of the first thin film 31 of the wafer W. (See Fig. 5 (a)). In this state, it is presumed that part of particles of the compound containing Ba and the compound containing Ti in the second coating film 32a generate barium titanate.

[0132] Then, after such vacuum drying is performed, the valve V4 is closed and the valve V5 is opened, and the purge gas is supplied into the sealed container 70 as described above to return the inside of the sealed container 70 to atmospheric pressure. Then, the lid 73 is opened, the wafer W is unloaded, and is transferred to a heating unit described later in the next process. Thereafter, the thinner liquid 45 remaining in the second coating film 32a is volatilized by the heating process, which is the pretreatment for baking described above. In addition, hydrolysis and condensation polymerization occur to form a barium titanate network structure that becomes a precursor film of barium titanate having an AB Ox-type bobsite crystal structure. Further, the second thin film 32 is formed by performing a baking process thereafter.

When the coating film forming step according to the third embodiment described above is performed, an effect that the second coating liquid 46 easily enters the gap 42 of the first thin film 31 is obtained. The reason for this will be explained below. As shown in FIG. 17 (a) and FIG. 17 (b), the air 44 4 entering the gap 42 of the first thin film 31 is obtained by the above-described reduced-pressure drying process performed after the second coating liquid 46 is applied. Is forcibly sucked out. Thus, the second coating liquid 46 enters the gap 42 from which the air 44 has been removed. As a result, it is presumed that the second coating liquid 46 can be quickly filled into the gaps 42 of the first thin film 31 as shown in FIG. 17 (c).

As described above, when the coating film forming step according to the third embodiment is performed, the second coating liquid 46 is more easily penetrated into the voids 42 of the first thin film 31, and the first thin film 31 A denser layer, that is, a layer having a higher density, is formed on the surface of the film, and the flatness is improved. As described above, when the second thin film 32 is formed on the first thin film 31 having high flatness, the result is an ABOx type base. The flatness of the surface of the dielectric film 3a having the mouth bskite crystal structure is improved.

[0135] When the capacitor is formed by forming the lower electrode 21 and the upper electrode 22 on both surfaces of the dielectric film 3a (see Fig. 1 (a)), the generation of leakage current can be further suppressed. it can. This is because a denser (higher density) film is formed near the boundary between the first thin film 31 and the second thin film 32, thereby making it difficult to form a conductive path in the dielectric film 3a. Because

[Fourth Embodiment of Coating Film Forming Process]

Next, a fourth embodiment of the coating film forming process will be described. In the coating film forming process of the present embodiment, as in the third embodiment, after the coating process of the second coating liquid 46, the vacuum drying process (penetration) Step). Then, the coating unit 6 and the vacuum drying unit 7 are used as in the third embodiment.

[0137] The second coating film forming process in the coating film forming step of the present embodiment is performed as follows. First, as shown in FIG. 18 (a), the coating unit 6 applies the second coating liquid 46 to the wafer W on which the first thin film 31 is formed in the manner of one stroke as described above. The Next, the wafer W having the surface of the first thin film 31 coated with the second coating liquid 46 is transferred to the vacuum drying unit 7, and on the mounting table 71 of the hermetic container 70 as shown in FIG. Placed on. Then, the valve V4 is opened, and the vacuum pump 75 is operated to start depressurization in the sealed container 70, and the pressure is higher than a predetermined pressure (for example, the pressure P1 (for example, lOOPa) under a temperature of 20 ° C. Pressure) until it reaches (pressure) (first decompression step). Here, the volatilization of the thinner liquid 45 in the second coating liquid 46 starts after the pressure P1 is reached, so it is presumed that at this stage, the thinner liquid 45 is volatilized and is in a state.

Next, the valve V4 is closed, and as shown in FIG. 18 (c), the valve V5 is opened and purge gas is supplied into the sealed container 70 to return the inside of the sealed container 70 to atmospheric pressure (pressure increase process). . Next, the valve V5 is closed, and as shown in FIG. 18 (d), the valve V4 is opened again, and the pressure reduction in the sealed container 70 is started by the vacuum pump 75. Then, the pressure is reduced for a predetermined time (for example, about 5 minutes) until the pressure in the sealed container 70 becomes lower than the pressure P1 under the condition of a temperature of 20 ° C. (second pressure reduction step). In this case, volatilization of the thinner liquid 45 in the second coating liquid 46 starts when the pressure in the sealed container 70 reaches the pressure P1. For this reason, the second decompression step If performed, most of the thinner liquid 45 in the second coating liquid 46 on the surface of the UENO W will volatilize.

Here, the change with time of the pressure in the sealed container 70 will be described with reference to FIG. 16 (b). First, when pressure reduction in the hermetic container 70 is started at time t4, the pressure in the hermetic container 70 (substantially equal to the atmospheric pressure at time t4) decreases rapidly. However, when the purge gas is supplied into the closed container 70 at the timing (time t5) before the pressure P1 decreases, the pressure in the container 70 returns to the atmospheric pressure at the time t6. Next, in the second depressurization step, the pressure decreases rapidly to the pressure P1 again. Then, after reaching pressure P1 (time t7), the pressure remains constant until time t8, but decreases more rapidly after time t8. Here, the state of Ueno, the first thin film 31 on the W surface, and the second coating liquid 46 when such pressure reduction is performed will be described. First, when the inside of the sealed container 70 is depressurized from the atmospheric pressure, as described above, the air 44 that has entered the gap 42 of the first thin film 31 is sucked (extruded) from the gap 42 and removed. Next, pressure reduction in the sealed container 70 is started again at time t6, and when the pressure decreases to pressure P1 (time t7), volatilization of the thinner liquid 45 in the second coating liquid 46 starts and the time until time t8 is reached. Volatilization continues.

[0140] By performing vacuum drying on the second coating liquid 46 on the wafer W in this manner, the second coating film 32a having a thickness of, for example, 180 nm is formed on the surface of the first thin film 31 of the wafer W. (See Fig. 5 (a)). In this state, it is presumed that part of particles of the compound containing Ba and the compound containing Ti in the second coating film 32a generate barium titanate.

[0141] Then, after such drying under reduced pressure, the purge gas is supplied into the sealed container 70 as described above to return the inside of the sealed container 70 to atmospheric pressure. Then, the lid 73 is opened and the wafer W is unloaded and transferred to a heating unit, which will be described later. Thereafter, the thinner liquid 45 remaining in the second coating film 32a is volatilized by the heating process, which is a pretreatment for the firing described above. In addition, hydrolysis and condensation polymerization occur, and a network structure of barium titanate that forms a precursor film of barium titanate having an ABOx type perovskite crystal structure is formed. Further, the second thin film 32 is formed by performing a baking process thereafter.

[0142] When the coating film forming step according to the fourth embodiment described above is performed, an effect is obtained that the second coating liquid 46 easily enters the gap 42 of the first thin film 31. The reason for this is as follows. And explain. As described above, in the first reduced-pressure drying (first decompression step), the inside of the sealed container 70 is increased to a pressure higher than the pressure P1, and the pressure is not reduced, so the thinner 45 in the second coating solution 46 is not reduced. Volatilization does not start. That is, as shown in FIG. 19 (a), only the air 44 that has entered the gap 42 of the first thin film 31 is removed. Then, when the reduced-pressure sealed container 70 returns to atmospheric pressure again (pressure increasing step), as shown in FIG. 19 (b), the air 44 with sufficient force to escape from the gap 42 is compressed and becomes smaller. As a result, the space of the gap 42 becomes larger, and the second coating liquid 46 enters here. Subsequently, by depressurizing the hermetic container 70 again (second depressurization step), as shown in FIG. 19 (c), the air 44 further escapes from the gap 42, and the thinner liquid 45 also volatilizes. Thus, the second coating liquid 46 further enters the gap 42 from which the air 44 has been removed. As a result, it is presumed that, as shown in FIG. 19 (d), the second coating liquid 46 can be quickly filled into the gaps 42 of the first thin film 31.

As described above, when the coating film forming step according to the fourth embodiment is performed, the second coating liquid 46 is more easily penetrated into the gaps 42 of the first thin film 31, and the first thin film 31 A denser layer, that is, a layer having a higher density, is formed on the surface of the film, and the flatness is improved. Thus, when the second thin film 32 is formed on the first thin film 31 having high flatness, as a result, the flatness of the surface of the dielectric film 3a having the ABOx type bevskite crystal structure is improved.

[0144] In addition, when the capacitor is formed by forming the lower electrode 21 and the upper electrode 22 on both surfaces of the dielectric film 3a (see Fig. 1 (a)), the generation of leakage current can be further suppressed. it can. This is because a denser (higher density) film is formed near the boundary between the first thin film 31 and the second thin film 32, thereby making it difficult to form a conductive path in the dielectric film 3a. Because

[0145] In the decompression step of the third embodiment and the first and second decompression steps of the fourth embodiment, the atmosphere in which the wafer W coated with the second coating liquid 46 is placed is defined as The air 44 entering the gap 42 of the thin film 31 is removed, but the reduced pressure atmosphere may be set so that the thinner liquid 45 does not volatilize (evaporate) from the second coating liquid 46. In addition, the reduced-pressure drying process may be completed while a large amount of the thinner liquid 45 remains in the second coating liquid 46 while setting the reduced-pressure atmosphere in which the thinner liquid 45 volatilizes from the second coating liquid 46. Good.

[0146] In the coating film forming step according to the third embodiment and the fourth embodiment, the coating unit 6 is used as the coating apparatus. However, the first embodiment and the second embodiment are described. The coating unit 5 may be used in the same manner as the coating film forming step according to the state.

[0147] Next, a dielectric film forming system having an ABOx type perovskite crystal structure according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 20 is a schematic plan view of a forming apparatus provided in the dielectric film forming system according to the present embodiment, and FIG. 21 is a perspective view of the forming apparatus. In FIG. 20 and FIG. 21, S1 is a carrier station. In S1, a carrier placing portion 81 and a delivery means 82 are provided. The carrier placement unit 81 places a carrier C containing a plurality of (for example, 25) wafers W. The delivery means 82 delivers Weno and W with the carrier C.

[0149] A processing unit S2 surrounded by a casing 83 is connected to the back side of the delivery means 82. A main transport means 84 is provided at the center of the processing section S2. In the vicinity of the main transport means 84, shelf units Ul, U2 and U3 are arranged in which coating units 5 and Z or coating unit 6 forming a plurality of coating devices, heating and cooling units, etc. are stacked in multiple stages, respectively. ing. As for the coating unit 5 (6), the first coating liquid coating process and the second coating liquid coating process may be performed in different coating units 5 (6). 5 (6) may be used. In the latter case, only the coating solution needs to be changed.

[0150] The shelf units Ul, U2, and U3 are configured by combining various units for performing pre-processing and post-processing of the coating unit 5 (6). The combination includes a heating unit 9 for performing a beta treatment, a vacuum drying unit 7, a wafer W delivery unit, and the like. The heating unit 9 functions as a heating device that heats (bakes) the wafer W whose surface is coated with the coating liquid by the coating unit 5 (6) and volatilizes the solvent in the coating liquid. As for the heating unit 9, the heat treatment of the first coating film 31a and the heat treatment of the second coating film 32a may be performed by different heating units 9, or the same heating unit 9 is used. May be implemented.

[0151] Further, the main transport means 84 is configured to be movable in the vertical and horizontal directions and to be rotatable around the vertical axis. Due to the configuration, the main transfer means 84 can transfer the wafer W between the units constituting the coating unit 5 (6) and the shelf units Ul, U2, U3. 會 It is wrong.

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 81. On the surface of the wafer W accommodated in the carrier C, a lower electrode 21 is formed. Next, the wafer W is also taken out from the carrier C by the delivery means 82 and delivered to the main transport means 84 via the delivery unit which is one of the shelves of the shelf unit U 3. The main transfer means 84 transfers the wafer W to the coating unit 5 (6).

In the coating unit 5 (6), a process of coating the first coating liquid on the surface of the lower electrode 21 on the transported wafer and W is performed. Thereafter, the wafer W is transferred to the heating unit 9 and subjected to a heat treatment (beta treatment). After the beta processing, the wafer W is once returned into the carrier C on the carrier mounting portion 81 via the main transfer means 84 and the delivery means 82. The wafer W returned to the carrier C is transferred to a baking apparatus (described later) for performing a baking process, and heated by the baking apparatus (baking process). Thereby, the first thin film 31 is formed.

The wafer W on which the first thin film 31 is formed is transferred to the coating unit 5 (6) that performs the coating process of the second coating liquid 46 via the delivery unit 82 and the main transfer unit 84. In the second coating unit 5 (6), a process of coating the second coating solution 46 on the surface of the first thin film 31 formed on the transferred wafer W is performed. Thereafter, the wafer W is transferred to the reduced pressure drying unit 7 when necessary, where the reduced pressure drying process is performed. Next, the wafer W is transferred to the heating unit 9 and subjected to a heat treatment (beta treatment). After the beta process, the wafer W is once returned into the carrier C on the carrier mounting portion 81 via the main transfer means 84 and the delivery means 82. The wafer W returned to the carrier C is transferred to a baking apparatus (to be described later) for performing a baking process and heated by the baking apparatus (baking process). Thereby, the second thin film 32 is formed.

[0155] Next, the heating unit 9 for performing the beta treatment will be briefly described with reference to FIG. As shown in FIG. 22 (a), a base 95 formed in a cylindrical shape with a bottom is provided inside the casing 90 of the heating unit 9. In addition, for example, a circular hot plate 92 is provided in the base 95. When the wafer W is loaded onto the cooling plate 91 in the housing 90, the wafer W is transferred to the hot plate 92 by the cooling plate 91. When wafer W is placed on hot plate 92 As shown in FIG. 22B, the rectifying top plate 93 is lowered, and the peripheral portion of the top plate 93 and the peripheral portion of the base 95 are brought into close contact with each other via the O-ring 94. As a result, the periphery of the wafer W becomes a sealed space. Thereafter, for example, while supplying gas from the gas supply unit 96 into the sealed space, suction and exhaust are performed from the exhaust port 98 at the center of the top plate 93 by the suction mechanism 97. In this way, the heat treatment is performed while forming an air current (see the arrow in FIG. 22B) that is directed from the outer periphery to the center of the wafer W.

Next, a firing apparatus provided in the dielectric film formation system according to the present embodiment will be described. FIG. 23 is a schematic configuration diagram of a heating furnace 10 which is an example of a baking apparatus. The heating furnace 10 is a baking apparatus for changing (baking) the internal state of the coating film after the beta treatment into an amorphous state force crystallization state. As shown in FIG. 23, the heating furnace 10 includes a vertical reaction tube 100 having a double tube structure, for example. Further, a plurality of wafers W are accommodated in the wafer boat 101 in the reaction tube 100 at a predetermined interval in the vertical direction. In this state, for example, gas is supplied into the reaction tube 100 from the gas supply tube 102 and the suction tube 103 is evacuated and exhausted. In this manner, the wafer W is heated by the heating means 104 provided outside the reaction tube 100 while forming a gas stream, whereby the baking process is performed.

Example

[0157] Next, an example of the experiment 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. 24 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 111 is oxidized and an SiO film 112 having a thickness of about lOOnm is formed on the upper layer side.

2 Form. Then, a Pt layer 113 having a thickness of about 30 nm as a lower electrode is formed thereon.

Next, a dielectric film 3a having an ABOx type perovskite crystal structure to be measured is formed on the upper surface of the Pt layer 113. Then, an aluminum (A1) layer 114 as an upper electrode is formed on the upper surface of the dielectric film 3a. Subsequently, the A1 layer 114 is put into a disk shape having a diameter of about 0.25 mm to 10 mm. Next, the dielectric film 3a is put into the shape shown in FIG. Then, the Pt layer 113 is exposed.

[0159] The dielectric film 3a to be measured is formed on the first thin film 31 made of barium titanate having an ABOx type perovskite crystal structure and barium titanate having an ABOx type perovskite crystal structure. And a second thin film 32 having a thickness of lOOnm. The dielectric film 3a is formed through the technique described in the first embodiment of the coating film forming step.

[0160] The measurement device 115 is connected to the electrical property measurement sample manufactured as described above (connected between the Pt layer 113 and the A1 layer 114), and the leakage current and dielectric of the dielectric film 3a are measured. The electric capacity of the body membrane 3a was measured.

[0161] Regarding the leakage current of the dielectric film 3a, at room temperature, a bias voltage of 2V was applied between the Pt layer 113 and the A1 layer 114 for 15 seconds, and per unit area flowing through the dielectric film 3a at that time. The average value of current was detected.

[0162] Regarding the electric capacity of the dielectric film 3a, the bias voltage is OV or IV at room temperature.

Applying a voltage between Pt layer 113 and A1 layer 114 under the conditions of Vrms (capacitance measurement AC voltage) of 10 mV and frequency of lkHz to lMHz, the current and frequency flowing at that time are detected. Calculated force.

As a result, the leakage current of the dielectric film 3a in which the first thin film 31 and the second thin film 32 are laminated is

9. an 8 X 10 ^_9 AZcm ^2, the electric capacity was 1. 5 μ Y / cra.

[0164] (Example 2)

The sample for measuring electrical characteristics used in this example is obtained by using the dielectric film 3a formed through the technique described in the second embodiment of the coating film forming step. 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.

[0165] leakage current result, the dielectric film 3a is 9. a 4 X 10 ^_9 AZcm ^2, electrical capacitance, mediation 7 this in 1. 46 ^ ¥ / cm.

[Example 3]

The sample for measuring electrical characteristics used in this example is obtained by using the dielectric film 3a formed by the method described in the third embodiment of the coating film forming step. Other than this point This 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.

[0167] As a result, the leakage current of the dielectric film 3a is 9. 7 X 10 ^_9 AZcm ^2, electric capacity,

1. 7 pieces at 62 μ ¥ / cm.

[Example 4]

The sample for measuring electrical characteristics used in this example uses the dielectric film 3a formed by the method described in the fourth embodiment of the coating film forming step. 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.

[0169] leakage current result, the dielectric film 3a is 9. was 8 X 10 ^_9 AZcm ^2, electrical capacitance, mediation 7 this in 1. 64 ^ Y / cm.

[0170] (Comparative Example 1)

A dielectric film having a configuration in which a second thin film 32 is laminated on a first thin film 31 was prepared as a dielectric film 3a used for a sample for measuring electrical characteristics. The second thin film 32 of the dielectric film 3a is formed by applying the second coating liquid 46 directly on the surface of the first thin film 31 by spin coating under the same conditions as the first thin film 31, and then performing a heating process. And formed through a firing step. In the same manner as in Example 1, the leakage current and electric capacity of the dielectric film 3a were measured.

As a result, the leakage current of the dielectric film 3a is ^8.1 X 10 ^_8 AZcm ² , and the electric capacity is

1. It was 2 μ ¥ / cm.

[0172] (Comparative Example 2)

As the dielectric film 3a 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. Then, 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 was 1.3 X 10 ^_2 AZcm ² , and the electric capacity was 0.9 F / cm ² . [0174] (Comparative Example 3)

As the dielectric film 3a used for the sample for measuring electrical characteristics, a dielectric film having a configuration including only the second thin film 32 of lOOnm thickness made of barium titanate having an ABOx type perovskite crystal structure was prepared. Then, 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 is 2. an 8 X 10 ^_3 AZcm ^2, the electric capacity was 0. 7 μ Y / cm.

[0175] From the above results, when the dielectric film 3a having the first thin film 31 and the second thin film 32 (Examples 1 to 4, Comparative Example 1) was used. Compared to the configuration using only the first thin film 31 (Comparative Example 2) and the configuration including only the second thin film 32 (Comparative Example 3), the leakage current with a larger electric capacity is larger. It was confirmed to be smaller.

[0176] Even if the dielectric film 3a includes the first thin film 31 and the second thin film 32, the second thin film 32 is formed through the method of the coating film forming process of the present invention. In this case (Examples 1 to 4), it was confirmed that the leakage current was large and the electric current was large compared to the case where the first thin film 31 was formed by the same method (Comparative Example 1). As a result, the dielectric film 3a having the ABOx type bottom bumskite crystal structure including the first thin film 31 and the second thin film 32 formed on the upper layer side is formed into the coating film forming step of the present invention. It is understood that when this method is used, high electrical characteristics can be secured when this dielectric film 3a is used as a dielectric film of a capacitor.

[0177] 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.

[0178] Regarding this application, the Japanese Patent Application Patent Application No. 2005-2 filed on August 24, 2005.

The priority based on No. 43317 is claimed, and all the contents of the basic application are incorporated in the present application.

Industrial applicability

[0179] When a dielectric film obtained by the method or system for forming a dielectric film having an ABOx type perovskite crystal structure according to the present invention is used for a capacitor, leakage current is generated. The raw can be suppressed as much as possible. Therefore, the dielectric film having an ABOx type perovskite crystal structure obtained by the present invention is expected to be applied to a capacitor mounted on a circuit that requires more stability such as a power supply circuit for a CPU.

Claims

The scope of the claims

[1] 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;

Application in which a dielectric forming composition 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 solvent is applied onto the first dielectric thin film Process,

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.

[2] The method further includes a step of applying a predetermined solvent to the surface of the first dielectric thin film before the applying step, and replacing the air in the gap with the predetermined solvent. The method for forming a dielectric film having an ABOx type perovskite structure according to claim 1.

[3] The ABOx type according to [1], wherein the coating step includes a step of supplying the dielectric forming composition liquid until a liquid deposit is formed on the first dielectric thin film. A method for forming a dielectric film having a velovskite structure.

[4] The ABOx type perovskite structure according to [3], wherein the coating step includes a step of widening the liquid accumulation portion by rotating the first dielectric thin film. A method for forming a dielectric film.

[5] The method according to claim 1, further comprising a permeation step of sucking air in the gap and allowing a part of the composition liquid for dielectric formation to penetrate into the gap before the firing step. A method for forming a dielectric film having an ABOx type perovskite structure as described.

6. The infiltration step includes a depressurization step of placing the resultant product obtained in the application step in a sealed space and depressurizing the sealed space to a predetermined pressure or less. A method for forming a dielectric film having an ABOx type perovskite structure.

[7] In the pressure reducing step, the inside of the sealed space is contained in the dielectric forming composition liquid. 7. The method for forming a dielectric film having an ABOx type perovskite structure according to claim 6, wherein the pressure is reduced to a pressure equal to or lower than a pressure at which volatilization of a predetermined solvent is started.

[8] The infiltration step includes a first depressurization step of placing the resultant product obtained in the application step in a sealed space and depressurizing the sealed space to a first pressure;

A pressure increasing step for increasing the pressure in the sealed space from the first pressure to a predetermined pressure; and a second pressure reducing pressure for reducing the pressure in the sealed space from the predetermined pressure to a second pressure lower than the first pressure. Process,

The method for forming an insulator film having an ABOx type perovskite structure according to claim 5, comprising:

[9] In the second depressurizing step, the inside of the sealed space is depressurized to a pressure below which the volatilization of the predetermined solvent contained in the dielectric forming composition liquid is started. Item 9. A method for forming a dielectric film having an ABOx type perovskite structure according to Item 8.

[10] The step of preparing the first dielectric thin film comprises:

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 coating a surface of the substrate with a dielectric forming composition liquid containing particles;

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; and a firing step for the first dielectric thin film. 2. The method for forming an insulator film having an ABOx type perovskite structure according to claim 1.

[11] The dielectric 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. 2. The method for forming a dielectric film having an ABOx type perovskite structure according to claim 1, comprising at least one compound and a predetermined solvent.

[12] 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. The AB according to claim 11, characterized in that A method for forming a dielectric film having an Ox-type perovskite crystal structure.

[13] The dielectric forming composition liquid for forming the first dielectric thin film is obtained by hydrolyzing the dielectric forming composition liquid for forming the second dielectric thin film. 11. The method for forming a dielectric film having an ABOx-type perovskite crystal structure according to claim 10, characterized in that it includes particles having an average particle diameter of lOOnm or less having an integer of 1 or more) -type crystal structure.

[14] In a system for forming a dielectric film having an ABOx type perovskite structure composed of a laminated film 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, it is smaller than the average diameter of the above-mentioned voids. A coating apparatus for applying a dielectric forming composition liquid containing particles having a predetermined solvent and a predetermined solvent;

The resultant obtained by applying the dielectric forming composition liquid by the coating apparatus is baked to form a second dielectric thin film having an ABOx type bobsite crystal structure on the first dielectric thin film. A baking apparatus to be formed;

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

[15] The application is characterized in that the coating apparatus includes a solvent applying unit that applies only the predetermined solvent contained in the dielectric forming composition liquid for forming the second dielectric thin film. Item 15. A dielectric film formation system having an ABOx type perovskite structure according to Item 14.

[16] The apparatus further comprises a permeation device that sucks air in the gap and infiltrates a part of the dielectric forming liquid for forming the second dielectric thin film into the gap. 15. A dielectric film forming system having an ABOx type perovskite structure according to claim 14.

[17] The permeation device includes a sealed container that accommodates a result obtained by applying the dielectric forming composition liquid for forming the second dielectric thin film by the coating device;

17. The system for forming a dielectric film having an ABOx type perovskite structure according to claim 16, further comprising: a decompression unit that decompresses the inside of the sealed container to a predetermined pressure or less.

[18] The depressurizing means depressurizes the sealed container to a pressure equal to or lower than a pressure at which volatilization of the predetermined solvent contained in the dielectric forming composition liquid for forming the second dielectric thin film is started. 18. The dielectric film forming system having an ABOx type perovskite structure according to claim 17.

[19] The permeation device includes a sealed container that accommodates a result obtained by applying the dielectric forming composition liquid for forming the second dielectric thin film by the coating device;

First decompression means for depressurizing the inside of the sealed container to a first pressure;

A pressure increasing means for increasing the pressure in the sealed container from the first pressure to a predetermined pressure, and a second pressure reducing pressure for reducing the pressure in the sealed container from the predetermined pressure to a second pressure lower than the first pressure. The system for forming a dielectric film having an A BOx type perovskite structure according to claim 16, further comprising: means.

[20] The second depressurizing means depressurizes the sealed container to a pressure equal to or lower than a pressure at which the predetermined solvent contained in the dielectric forming composition liquid for forming the second dielectric thin film is started. 20. The dielectric film forming system having an ABOx type perovskite structure according to claim 19,