JPH06290984A - High dielectric-constant capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a high dielectric-constant capacitor, which is used as a capacitor for a semiconductor storage device and in which capacitor characteristics are not deteriorated even in the heat treatment in a manufacturing process, while providing the capacitor having a high dielectric constant and small leakage currents regardless of heat treatment, manufacture thereof and a dielectric film for the capacitor. CONSTITUTION:A dielectric film 4 consisting of a dielectric material mainly comprising a metallic oxide and a pair of lower and upper electrodes 3, 5 oppositely faced while holding the dielectric film are formed, and a protective film 1 preventing oxygen deficiency is formed onto the upper electrode 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor for a semiconductor memory device, which is mainly composed of a metal oxide and uses a dielectric film having a large dielectric constant, a method for manufacturing the same, a manufacturing apparatus therefor, and a dielectric film for a capacitor.

[0002]

2. Description of the Related Art A capacitor used in a current semiconductor memory device is an electrode made of a pair of polycrystalline silicon or the like in which a dielectric film made of a silicon oxide film or a silicon nitride film or a laminated body of them is opposed. It has a structure sandwiched between. A capacitor of this structure is a DRAM (Dyna
mic Random Access Memory)
It is widely used in memory cells of.

Such a semiconductor memory device has been integrated more and more due to the recent progress of miniaturization technology. The progress of integration has forced the reduction of the chip area, and consequently the occupied area of the capacitor cell with respect to the chip area. However, the reduction of the capacitor area leads to the reduction of the accumulated charge capacity of the capacitor. Since a certain amount of accumulated charge is required to function as a memory device, a capacitor cell having a three-dimensional structure has been developed so far in order to increase the electrode area of the capacitor.

However, a complicated manufacturing process is required to manufacture a cell having a three-dimensional structure, resulting in an increase in manufacturing equipment cost and manufacturing cost, which is a factor to put pressure on the semiconductor business. Therefore, there is a strong demand to reduce the manufacturing cost by simplifying the capacitor cell structure.

On the other hand, by manufacturing a capacitor with a dielectric material having a large dielectric constant in place of the conventional silicon oxide or silicon nitride, a capacitor having a simple planar structure can be constructed even if the degree of integration increases. . As a dielectric material for this high dielectric constant capacitor, SrTiO ₃ system, PZT (PbZrO ₃ -PbTiO ₃ ) have been used so far.
Materials based on solid solution) and metal oxides such as Ta ₂ O ₅ have been developed.

A conventional capacitor is disclosed in, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent No. 110861, Japanese Patent Laid-Open No. 3-126252, Japanese Patent Laid-Open No. 60-205913, etc., a lower electrode, a dielectric film and an upper electrode are laminated on a silicon wafer substrate with an insulating film interposed therebetween. Is formed. A barrier layer may be formed between the lower electrode and the dielectric film. In many cases, platinum Pt is used for the upper and lower electrodes.

[0007]

The high dielectric constant material containing a metal oxide as a main component is required to have capacitor characteristics such as a high dielectric constant and a sufficiently small leakage current. However, it is known that many metal oxides suffer from oxygen deficiency in their production processes and various environments, resulting in deterioration of the characteristics as a dielectric and, in some cases, semiconductivity. Therefore, there is a problem that desired capacitor characteristics cannot be obtained depending on the film forming conditions of the capacitor and the processing method after the film formation.

Further, the manufacturing process of a semiconductor device is composed of many steps, and the number thereof may reach several hundreds. High dielectric constant capacitors are also exposed to the environment in these various manufacturing processes, but under the conditions there should be no degradation of their capacitor characteristics. For example, Pt
In a normal high dielectric constant capacitor using the upper electrode made of, there is a problem that when a temperature of 450 ° C. or higher is applied in a nitrogen atmosphere or in a vacuum, the dielectric characteristics are significantly deteriorated and the capacitor does not function.

Further, among the above-mentioned materials having a large dielectric constant such as SrTiO ₃ series and PZT series, there is a demand for a dielectric material for capacitors having a larger dielectric constant and a smaller leakage current.

The present invention has been made to solve the above problems, and an object thereof is to provide a capacitor in which the capacitor characteristics due to oxygen deficiency do not deteriorate even in the heat treatment process after the formation of the capacitor.

The present invention further provides a method of manufacturing a capacitor which has a large dielectric constant and a small leakage current even in the initial characteristics after the heat treatment process after the capacitor is formed, its manufacturing apparatus, and a dielectric film for a capacitor. Is intended to provide. Therefore, in the present invention,
A new dielectric material having improved permittivity or leakage current characteristics of the conventional material by adding an element having an effect of reducing the leakage current of the conventional dielectric material such as SrTiO ₃ system or PZT system provide.

[0012]

A high dielectric constant capacitor of the present invention comprises a dielectric film made of a high dielectric constant dielectric material containing a metal oxide as a main component, and a pair of opposed dielectric films sandwiching the dielectric film. In the high dielectric constant capacitor including the electrode, the protective film for suppressing oxygen deficiency of the dielectric material is formed on the upper electrode formed on the dielectric film.

The material of the protective film is (a) Ti, Al,
A nitride of at least one metal selected from the group consisting of W, Mo, Ta, Nb, V, Cr, Zr and Ga,
(B) an oxide of at least one metal selected from the group consisting of Ti, Al, Ta, Nb, Zr, Re, Mg and Sr, (c) Ti, W, Pt, Mo, Ta, Nb,
A silicate of at least one metal selected from the group consisting of V, Cr, Zr and Co, and (d) Ti,
It is desirable to be composed of at least one substance selected from the group consisting of at least one metal selected from the group consisting of W, Ta, Cu, Ge, Ni and Cr, or an alloy thereof.

Further, the protective film is preferably formed by laminating at least two kinds of the materials.

The high dielectric constant capacitor of the present invention is a semiconductor memory device comprising a dielectric film made of a dielectric material containing a metal oxide as a main component, and a pair of electrodes facing each other with the dielectric film sandwiched therebetween. A capacitor, wherein the dielectric film is 2
It is characterized in that it is composed of a laminated film of more than one kind of dielectric material.

According to a fifth aspect of the present invention, in the method of manufacturing a capacitor, a dielectric film made of a dielectric material containing a metal oxide as a main component is provided on the lower electrode, and the upper electrode is provided on the dielectric film. A method of manufacturing a capacitor for a semiconductor memory device, comprising:
After the dielectric film is formed, the dielectric film is cooled in an oxidizing atmosphere at a rate of 15 ° C./minute or less.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a capacitor in which a dielectric film made of a dielectric material containing a metal oxide as a main component is provided on a lower electrode, and an upper electrode is provided on the dielectric film. A method of manufacturing a capacitor for a semiconductor memory device, comprising:
After forming the upper electrode on the dielectric film, heat treatment is performed in an oxidizing atmosphere.

According to a seventh aspect of the present invention, there is provided a method for manufacturing a capacitor, in which a lower electrode is provided with a dielectric film made of a dielectric material containing a metal oxide as a main component, and the upper electrode is provided on the dielectric film. A method of manufacturing a capacitor for a semiconductor memory device, comprising:
After the dielectric film is formed, the heat treatment is performed in an oxidizing atmosphere in which the partial pressure of the oxidizing gas is 1 atm or more.

According to an eighth aspect of the method of manufacturing a capacitor of the present invention, a dielectric film made of a dielectric material containing a metal oxide as a main component is provided on the lower electrode, and the upper electrode is provided on the dielectric film. A method of manufacturing a capacitor for a semiconductor memory device, comprising:
The step of forming the dielectric film and the step of performing heat treatment in an oxidizing atmosphere that is continuous with the step of forming the dielectric film are repeated at least twice to provide a dielectric film having a predetermined thickness.

The dielectric film manufacturing apparatus according to the present invention is characterized in that a film forming mechanism, a heat treatment mechanism in an oxidizing atmosphere, and a substrate supporting mechanism having a substrate heating device are installed in one vacuum chamber. And

It is preferable that the heat treatment mechanism can raise the pressure to 1 atm or more.

The capacitor dielectric film of the present invention is
(Ba _1-x Sr _x ) TiO ₃ , a composition represented by a composition formula of 0 ≦ x ≦ 1 is added by adding 0.05 to 5 wt% of Mn element in a molecular formula of oxide Mn ₂ O _3. It is characterized by

The above (Ba _1-x Sr _x ) TiO ₃ , 0 ≦ x ≦
Pb (Zr _1-y Ti _y ) O ₃ , 0 ≦, instead of the composition 1.
By using the composition of y ≦ 1, a high-performance dielectric film for a capacitor can be similarly obtained.

Further, 2 to 1 of Pb element of the composition
It is preferable to replace 5 mol% with Sr.

Further, the dielectric film for a capacitor of the present invention is
In _{(Sr 1-z Ca z)} 3 Ti 2 O 7 having a composition composition of the formula, characterized by comprising a 0.4 ≦ z ≦ 0.8 a composition.

[0026] The _{(Sr 1-z Ca z)} 3 Ti 2 O 7, 0.4
Me ₂ O is added to the composition represented by ≦ z ≦ 0.8.
It is preferable to add 0.05 to 5 mol% of an oxide represented by the composition formula ₃ (Me represents any one of La, Nd, Sm, and Gd). Further, Mn element is added to this material by the molecular formula of Mn ₂ O ₃ of 0.0
It is more preferable to add 5 wt% to 5 wt%.

[0027]

According to the present invention, since the special protective film is provided on the upper electrode of the capacitor, oxygen deficiency during the manufacturing process of the capacitor can be suppressed. As a result, it is possible to suppress the deterioration of the characteristics of the capacitor,
Capacitor performance with stable high dielectric constant and small leakage current can be obtained.

According to the high dielectric constant capacitor of the present invention, which is composed of a laminated film of two or more kinds of dielectric materials, the characteristics of each dielectric material are compounded, so that excellent capacitor characteristics can be obtained.

In the method for producing a dielectric film of the present invention, by gradually cooling in an oxidizing atmosphere after stopping the film formation, oxygen vacancies can be suppressed in the process after the film formation is stopped until the substrate is taken out, which is stable. A characteristic dielectric film can be obtained.

Furthermore, after forming the upper electrode, heat treatment is carried out in an oxidizing atmosphere, whereby oxygen vacancies can be recovered, and a capacitor having excellent capacitor characteristics can be obtained.

Furthermore, after the dielectric film is formed, by performing heat treatment under a partial pressure of the oxidizing gas of 1 atm or more, oxygen deficiency during the heat treatment is suppressed, so that the dielectric film having excellent capacitor characteristics. You can get

Further, by repeating the film forming process and the heat treatment process in an oxidizing atmosphere two or more times, it is possible to form a film while recovering oxygen vacancies in the film forming process, so that an excellent capacitor with few oxygen vacancies can be obtained. It is possible to obtain a dielectric film having characteristics.

According to the dielectric film manufacturing apparatus of the present invention, since the film forming mechanism and the heat treating mechanism are provided in one vacuum apparatus, the film forming step and the heat treating step can be repeated, and oxygen It is possible to obtain a dielectric film having excellent capacitor characteristics with few defects.

Further, in the manufacturing apparatus of the present invention, since the film forming mechanism and the heat treatment mechanism capable of creating a high-pressure oxidizing atmosphere are provided in one vacuum apparatus, the film forming process and the heat treatment in the high-pressure oxidizing atmosphere can be performed. Can be done continuously. Therefore, it is easy to repeat the film forming step and the heat treatment step a plurality of times. As a result, it is possible to obtain a dielectric film having excellent capacitor characteristics with few oxygen defects.

According to the dielectric film for a capacitor of the present invention,
(Ba _1-x Sr _x ) TiO ₃ , 0 ≦ x ≦ 1, Pb (Zr _{1-y
Ti y) O 3, 0 ≦} y ≦ 1 or _{(Sr 1-z Ca z)} 3 Ti 2
By adding a trace amount of Mn element to a composition of O ₇ and 0.4 ≦ z ≦ 0.8, +3 valence ions of Ti element and its +4 valence ions due to oxygen defects generated during film formation are generated. The decrease in resistance due to the exchange of electrons during that period can be prevented by shortening the range of electron exchange by changing the valence of Mn itself. Therefore, a high dielectric property (low leakage current density) can be provided, and a dielectric film having excellent capacitor characteristics with few oxygen vacancies can be obtained.

In the present invention, by using a solid solution of Sr ₃ Ti ₂ O ₇ (relative permittivity = 38) and Ca ₃ Ti ₂ O ₇ (relative permittivity = 59) as the dielectric material, it is possible to obtain an intermediate composition range. The relative permittivity becomes significantly higher than the relative permittivity at both composition ends. Therefore, by selecting the composition range, a dielectric film having a sufficiently large dielectric constant can be obtained.

In the solid solution, the average value of the ionic radii of +2 valent ions of Sr and +4 valent ions of Ti (0.92
Lanthanide series element (L
By adding oxides of a, Nd, Sm, and Gd), the relative dielectric constant can be increased without increasing the leakage current density if the addition amount is up to 5 mol%.

[0038]

The capacitor of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the capacitor of the present invention. In FIG. 1, reference numeral 2 is a semiconductor substrate made of a silicon wafer substrate or the like, and a lower electrode 3 is formed on an insulating film 2a made of an oxide film or a nitride film provided on the surface by a thermal oxidation method, a CVD method, a sputtering method or the like. , The dielectric film 4 and the upper electrode 5 are sequentially formed to form a capacitor. The present invention is characterized in that a protective film 1 for preventing oxygen deficiency of the dielectric film 4 is further provided on the upper electrode 5. In the embodiment shown in FIG. 1 and the embodiment described below, the capacitor is formed on the insulating film provided on the surface of the semiconductor substrate. It is not limited to the example, and it may be formed on another field insulating film, a wiring film, or the like via an interlayer insulating film or the like. When a capacitor is formed on the interlayer insulating film, the lower electrode is connected to the transistor via a plug or the like.

The lower electrode 3 and the upper electrode 5 are made of a material such as platinum, palladium, or gold by, for example, a sputtering method or a vacuum vapor deposition method. Usually, the lower electrode 3 is preferably thinner in order to reduce the step difference. The upper electrode is not particularly limited to a thickness of 50 nm or less, but usually 100 n
It is formed to a thickness of about m.

The dielectric film 4 is preferably made of a material having a high relative dielectric constant of 100 or more, such as SrTi.
O ₃ system, PZT (PbZrO ₃ -PbTiO ₃ solid solution)
It is preferable to use a material containing a metal oxide as a main component, such as a BaTiO ₃ system, a BaTiO ₃ system, or a PLZT system, and using these materials as a target, a film is formed by an RF magnetron sputtering method, a sol-gel method, a CVD method, or laser ablation. The film is formed by a method or the like. The thinner the dielectric film 4 is, the larger the capacitance of the capacitor is, which is preferable.

Further, even if the protective film 1 is heat-treated in the manufacturing process of the semiconductor memory device after the formation of the capacitor, oxygen in the dielectric film 4 escapes and the leakage current in the dielectric film 4 does not increase. As described above, it prevents the escape of oxygen.
For example, the following materials can be used as the material of the protective film 1. (1) Ti, Al, W, Mo, Ta, Nb, V, Cr,
Metal nitrides such as Zr or Ga, eg Ti
N, AlN, WN, MoN, Ta ₄ N ₅ , NbN, VN,
Cr ₂ N, ZrN, GaN or the like is used. By using these nitrides as a protective film, they are stable against heat treatment in a nitrogen atmosphere, and therefore are excellent when there is a heat treatment in a nitrogen atmosphere in a subsequent step. (2) Oxides of metals such as Ti, Al, Ta, Nb, Zr, Re, Mg or Sr, for example, TiO ₂ , Al ₂ O
₃ , Ta ₂ O ₅ , Nb ₂ O ₅ , ZrO ₂ , ReO ₃ , MgO,
SrTiO ₃ or the like is used. Since these oxides can withstand heat treatment in an oxidizing atmosphere or in a high vacuum, they are excellent when there is a heat treatment in an oxygen atmosphere in a subsequent process. (3) Ti, W, Pt, Mo, Ta, Nb, V, Cr,
Silicates of metals such as Zr or Co, eg Ti
Si ₂ , WSi ₂ , PtSi ₂ , MoSi ₂ , TaSi ₂ ,
NbSi ₂ , VSi ₂ , CrSi ₂ , ZrSi ₂ or the like is used. These silicates are excellent because good contact is obtained when polysilicon is used for wiring. (4) A metal film such as Ti, W, Ta, Cu, Ge, Ni or Cr is used. Providing such a metal film on the upper electrode 5 is excellent in that it can withstand heat treatment in a vacuum or in a reducing atmosphere.

The protective film 1 is a single-layer film made of the above-mentioned various materials or a nitride film in each of the groups (1), (2), (3) and (4) or in a plurality of groups (for example, a nitride of (1)). Two or more layers of different materials may be laminated between the oxides of (2). In this case, a dielectric film having the advantages of each film can be obtained. To form these dielectric films, for example, RF magnetron sputtering method, CVD
(Chemical Vapor Deposition
n) method, MBE (Molecular Beam Epi)
The film can be formed by a taxy method, a vacuum evaporation method, a laser ablation method, or the like, and the film forming method is not particularly limited. The thickness of the film is not particularly limited as long as it is 50 nm or more, but it is preferably 300 nm or less in order to suppress a step on the capacitor, and 50 to 15
More preferably, it is 0 nm.

Next, specific examples will be described in more detail.

[Embodiment 1] The structure shown in FIG.
100 nm as a lower electrode 3 on a silicon wafer substrate 2 on which an insulating film 2a made of a thermal oxide film of 00 nm is formed
Platinum was deposited to a thickness of 1 by a sputtering method. On this substrate, a dielectric film 4 made of SrTiO _{3 having} a thickness of about 100 nm was formed at a substrate temperature of about 600 ° C. by an RF magnetron sputtering method using a SrTiO ₃ ceramic target. Further, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method similarly to the lower electrode to obtain a capacitor. In this embodiment, a TiN film is formed on the upper electrode 5 of the capacitor as a protective film 1 by sputtering with a target of metal Ti in a nitrogen atmosphere by sputtering.
It was formed to a thickness of 0 nm. Table 1 shows a comparison of the capacitor characteristics when the protective film according to the present invention is formed and when the protective film is not formed. It can be seen that when a capacitor without a protective film is heat-treated in a nitrogen atmosphere at about 800 ° C., the leak current significantly increases and does not function as a capacitor. In the capacitor of this example, deterioration of characteristics due to this heat treatment is not recognized. In addition, W shown in Table 1
N, AlN, MoN, Ta ₄ N ₅ , ZrN, GaN, Cr
The same effect was obtained by using a protective film made of ₂ N.
Further, similar effects can be obtained for NbN and VN.
In Table 1, “unmeasurable” means that the upper limit of the measuring device of 1 × 10 ⁻³ A / cm ² is exceeded (the same applies below).

[0046]

[Table 1] [Embodiment 2] Platinum having a thickness of about 100 nm is sputtered as a lower electrode 3 on a silicon wafer substrate 2 having a structure shown in FIG. 1 and having an insulating film 2a made of a thermal oxide film of about 300 nm formed thereon. A film was formed. SrT on this substrate
An S magnet having a thickness of about 85 nm at about 600 ° C. by an RF magnetron sputtering method using an iO ₃ ceramic target.
A dielectric film 4 made of rTiO ₃ was formed. Further, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method similarly to the lower electrode to obtain a capacitor. In this embodiment, as a protective film on this capacitor, an Al ₂ O ₃ ceramic is used as a target in a sputtering method of about 150 nm.
A protective film 1 made of Al ₂ O ₃ was formed. Then about 8
Heat treatment was performed at 00 ° C. in a nitrogen atmosphere, and the capacitor characteristics before and after the heat treatment are shown in Table 2. A capacitor without the protective film 1 does not function as a capacitor after this heat treatment. On the other hand, in the capacitor according to this example, deterioration of the capacitor characteristics due to this heat treatment was not recognized. TiO ₂ , ZrO ₂ , ReO ₃ , Ta ₂ O ₅ , Nb shown in Table 2
Similar results were obtained with ₂ O ₅ , MgO and SrTiO ₃ . Since the oxide film is generally stable, it has the advantage that it can withstand heat treatment in an oxygen atmosphere or in a high vacuum.

[0047]

[Table 2] [Embodiment 3] Platinum having a thickness of about 100 nm is formed as a lower electrode 3 on a silicon wafer substrate 2 having a structure shown in FIG. 1 and an insulating film 2a made of a thermal oxide film having a thickness of about 300 nm by a sputtering method. A film was formed. SrT on this substrate 2
Approximately 100 n at a substrate temperature of approximately 600 ° C. by an RF magnetron sputtering method using an iO ₃ ceramic target.
m dielectric film 4 was formed. Further, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method similarly to the lower electrode to obtain a capacitor. In this embodiment, a TiSi ₂ compound target is used on this capacitor,
Approximately 100 nm Ti using argon gas as sputtering gas
The Si ₂ protective film 1 was formed. Table 3 shows a comparison of the capacitor characteristics when the protective film according to the present invention is formed and when it is not formed. Without the protective film, heat treatment of the capacitor in vacuum at about 800 ° C. significantly increased the leak current. On the other hand, no deterioration of the characteristics was observed in the capacitor of this example. In addition, PtS shown in Table 3
i ₂ , WSi ₂ , MoSi ₂ , ZrSi ₂ , TaSi ₂ , C
The same effect was obtained by using a protective film made of rSi ₂ . Similar effects can be obtained with VSi ₂ and NbSi ₂ .

[0048]

[Table 3] [Embodiment 4] Platinum having a thickness of about 100 nm is sputtered as a lower electrode 3 on a silicon wafer substrate 2 having a structure shown in FIG. 1 and having an insulating film 2a made of a thermal oxide film of about 300 nm formed thereon. A film was formed. SrTi on this substrate
About 100 nm at a substrate temperature of about 600 ° C. by an RF magnetron sputtering method using an O ₃ ceramic target.
A dielectric film 4 made of SrTiO ₃ was formed. Next, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the same sputtering method as the lower electrode to obtain a capacitor.
In this embodiment, metal Ti is further formed on the capacitor.
Using a target, a Ti protective film 1 having a thickness of about 100 nm was formed using argon gas as a sputtering gas. Table 4 shows a comparison of the capacitor characteristics between when the protective film according to this example is formed and when it is not formed. Without the protective film, heat treatment of the capacitor in vacuum at about 800 ° C. significantly increased the leak current. In the capacitor of this example, deterioration of characteristics due to this heat treatment was not recognized.
In addition, W, Ni-Cr, Ta, and Ge shown in Table 4 are used.
In addition to the above, the same effect was obtained by using a Cu film as a protective film. It should be noted that the use of the metal film as the protective film has an advantage that it can withstand heat treatment in a vacuum or in a reducing atmosphere.

[0049]

[Table 4] [Embodiment 5] FIG. 2 is a schematic sectional view showing the structure of a capacitor according to a fifth embodiment of the present invention. On the silicon wafer substrate 2 on which the insulating film 2a made of a thermal oxide film having a thickness of about 300 nm was formed, platinum was deposited as the lower electrode 3 to a thickness of about 100 nm by a sputtering method. SrT on this substrate 2
A dielectric film 4 having a thickness of about 100 nm was formed at about 600 ° C. by an RF magnetron sputtering method using an iO ₃ ceramic target. Further, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method similarly to the lower electrode to obtain a capacitor. In this embodiment, a TiN film (about 50 nm) 7a similar to that of the first embodiment is formed on the upper electrode, and then an Al ₂ O ₃ film (about 5 nm) similar to that of the second embodiment is formed thereon.
0 nm) 6a was deposited to form a protective film 1 having a laminated structure. This capacitor was heat-treated at about 800 ° C. in a nitrogen atmosphere, and the capacitor characteristics before and after the heat treatment are shown in Table 5.
A capacitor without a protective film does not function as a capacitor after this heat treatment. In the capacitor according to this example, deterioration of the capacitor characteristics due to heat treatment was not recognized. Table 5
Similar results were obtained when TiSi ₂ and Ti shown in ( ₃ ) were formed to the same thickness on the TiN film 7a. When the oxidizing process, the nitrogen atmosphere, or the heat treatment in vacuum is performed in one manufacturing process, it is effective to prevent the capacitor film from deteriorating by forming the protective film in a laminated structure. The laminated structure of the protective film may be any combination of two or more kinds of materials as long as the materials are enumerated in Examples 1 to 4, and there is no particular limitation. It is preferable that the oxide film and the nitride film are laminated in this order. Further, the thickness of the entire protective film is preferably 150 nm or less in order to reduce the step. Therefore, a two-layer or three-layer structure is preferable.

[0050]

[Table 5] [Embodiment 6] FIG. 3 is a schematic sectional view showing the structure of a capacitor according to a sixth embodiment of the present invention. On the silicon wafer substrate 2 on which the insulating film 2a made of a thermal oxide film of about 300 nm was formed, about 100 nm of platinum was formed as the lower electrode 3 by the sputtering method. On this substrate, an SrTiO ₃ dielectric film 4 of about 100 nm was formed at about 600 ° C. by an RF magnetron sputtering method using a SrTiO ₃ ceramic target. Further, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method similarly to the lower electrode to obtain a capacitor. In this embodiment, a SiO ₂ film (50 nm) 7b similar to that of the second embodiment is formed as the protective film 1, and then a TiN film (50 nm) similar to that of the first embodiment is formed thereon.
6b was deposited to form a protective film 1 having a laminated structure. Then,
RIE (Reactive Ion Etching)
A hole having an opening diameter of about 5 μm was formed in the protective film 1 by the method. After that, aluminum 1 is formed in the opening 10 by a sputtering method.
1 was embedded to form an electrode wiring 11 electrically connected to the upper electrode 5. In this embodiment, good electrical connection with the upper electrode 5 of the capacitor can be achieved regardless of the type of material of the protective film 1.

In this embodiment, the material for the electrode wiring may be polysilicon, tungsten, titanium, chromium, cobalt, silicon compounds or nitrides thereof, aluminum alloy, copper alloy, etc., in addition to aluminum. The method for forming the electrode wiring is not particularly limited, and other than the sputtering method, it can be formed by the CVD method, the MBE method, the vapor deposition method, the laser ablation method, or the like.

[Embodiment 7] FIG. 4 is a schematic sectional view showing the structure of a capacitor according to a seventh embodiment of the present invention. About 300
On the silicon wafer substrate 2 on which the insulating film 2a made of a thermal oxide film having a thickness of 10 nm was formed, about 100 nm of platinum was deposited as the lower electrode 3 by a sputtering method. SrT on this substrate
Approximately 100 n at a substrate temperature of approximately 600 ° C. by an RF magnetron sputtering method using an iO ₃ ceramic target.
m SrTiO ₃ film 4a was formed. Next, using a ceramic target made of aluminum nitride,
An aluminum nitride film 4b having a thickness of 50 nm was formed by using a mixed gas of Ar and N ₂ to obtain a dielectric film 4 having a laminated structure.
Further, platinum was formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method similarly to the lower electrode to obtain a capacitor. Heat treatment was performed in a nitrogen atmosphere at about 800 ° C., and the capacitor characteristics before and after the heat treatment are shown in Table 6. In the capacitor according to this example, deterioration of the capacitor characteristics due to this heat treatment was not recognized.

[0053]

[Table 6] [Embodiment 8] FIG. 5 is a schematic sectional view showing the structure of an eighth embodiment of the capacitor of the present invention. On the silicon wafer substrate 2 on which the insulating film 2a made of a thermal oxide film of about 300 nm was formed, about 100 nm of platinum was formed as the lower electrode 3 by the sputtering method. An SrTiO ₃ film 4a was formed on this substrate by RF magnetron sputtering using a SrTiO ₃ ceramic target at a temperature of about 600 ° C. and a thickness of about 70 nm. On top of that (Ba _0.7 Sr _0.3 ) TiO ₃
Using the ceramic target having the composition, the (Ba, Sr) TiO ₃ film 4c was formed to a thickness of about 70 nm to form the dielectric film 4. Further, platinum is formed as the upper electrode 5 to a thickness of about 100 nm by the sputtering method like the lower electrode,
I got a capacitor. As a comparative example, a capacitor having a film thickness of about 150 nm and made only of the (Ba, Sr) TiO ₃ film 4c and a capacitor made of only the SrTiO ₃ film 4a were formed by the same method, and the characteristics at room temperature are shown in Table 7. Using a prober equipped with a heat stage, the temperature change of the relative dielectric constant was measured. The results are shown in Fig. 6. In this embodiment, the dielectric constant is large and the leakage current is slightly large (Ba, S
r) By stacking the TiO ₃ film and the SrTiO ₃ film having a relatively small dielectric constant but a small leakage current, an excellent capacitor having a large dielectric constant and a small leakage current was obtained. From FIG. 6, it is clear that the capacitor is also a capacitor whose dielectric constant changes little with temperature. In addition to this example, if a capacitor having a large dielectric constant but a large leakage current and a capacitor having a small leakage current even if the dielectric constant is not so large are laminated, a capacitor having the respective advantages can be obtained. For example, a combination of a PZT film having a large dielectric constant and an SrTiO ₃ film having a poor dielectric constant but excellent leakage current characteristics may be used. As described above, by stacking the dielectric films in this embodiment, it is possible to obtain a capacitor having excellent characteristics as compared with a capacitor made of a film having a single structure.

[0054]

[Table 7] [Ninth Embodiment] FIG. 7 is a schematic sectional view of the structure of a ninth embodiment of the capacitor of the present invention. On the silicon wafer substrate 2 on which the insulating film 2a made of a thermal oxide film of about 300 nm was formed, about 100 nm of platinum was formed as the lower electrode 3 by the sputtering method. A dielectric film 4 of about 70 nm was formed on this substrate at about 600 ° C. by an RF magnetron sputtering method using a SrTiO ₃ ceramic target. Immediately after the film formation, oxygen gas was introduced, and the substrates were
150 at speeds of 40 ° C, 25 ° C, 15 ° C and 5 ° C per minute
After cooling to ℃, it was taken out into the atmosphere, and then the upper electrode 5 was provided. Table 8 shows the capacitor characteristics for each cooling rate. As a result, when cooled at a rate of 15 ° C./min or less, it fell below the regulation value of leakage current of 6 × 10 ⁻⁸ A / cm ^2, and a good capacitor was obtained.

[0055]

[Table 8] [Embodiment 10] With the structure shown in FIG. 7, about 100 nm of platinum was deposited as the lower electrode 3 by sputtering on the silicon wafer substrate 2 on which the insulating film 2a of about 300 nm of thermal oxide film was formed. . On this substrate 2 SrTiO
_A dielectric film 4 made of SrTiO ₃ having a thickness of about 70 nm was formed at a substrate temperature of about 600 ° C. by RF magnetron sputtering using a ceramic target. further,
Platinum having a film thickness of about 70 nm was formed as the upper electrode 5 by the same sputtering method as the lower electrode to obtain a capacitor. This was held at about 700 ° C. in an oxygen atmosphere for about 30 minutes. Table 9 shows the capacitor characteristics at that time. When the upper electrode 5 is formed after the same heat treatment is performed in a state where the upper electrode 5 is not formed, the capacitor characteristics are deteriorated. The thickness of the upper electrode 5 is not particularly limited as long as it is 50 nm or more. In the manufacturing method of the present invention, the improvement of the capacitor characteristics is recognized.

[0056]

[Table 9] [Example 11] Platinum was formed as a lower electrode by sputtering to a thickness of about 100 nm on a silicon wafer substrate on which an insulating film made of a thermal oxide film of about 300 nm was formed. On this substrate, an SrTiO ₃ ceramic target was used to produce about 600 by RF magnetron sputtering.
A dielectric film having a thickness of about 70 nm was formed at a temperature of ° C. Further, platinum is used as the upper electrode in the same manner as the lower electrode by the sputtering method to about 100.
A capacitor having a thickness of nm was obtained. This is oxygen H
IP (Hot Isostatic Pressin
g) Put in the device, change the oxygen mixing ratio so that the oxygen partial pressure becomes 100 atm and 10 atm, and about 15 ° C at about 600 ° C.
Hold for minutes. Table 10 shows the characteristics of the capacitors subjected to the heat treatment according to the present invention. The capacitor characteristics when the same capacitor is heat-treated in a vacuum apparatus with oxygen partial pressures of 1 atm, 0.3 atm and 0.1 atm are also shown. According to the present invention, as is clear from Table 10, the heat treatment under the oxygen partial pressure of 1 atm or more can reduce the leak current of the capacitor film to a value lower than that at the time of film formation. The heat treatment temperature may be 450 ° C. or higher, but if it is 800 ° C. or higher, improvement in characteristics cannot be expected. It is preferably in the range of 500 to 700 ° C.

[0057]

[Table 10] [Example 12] Platinum having a thickness of about 100 nm was formed as a lower electrode by a sputtering method on a silicon wafer substrate on which an insulating film made of a thermal oxide film having a thickness of about 300 nm was formed. A dielectric film was formed on this substrate by RF magnetron sputtering using a SrTiO ₃ ceramic target at a substrate temperature of about 600 ° C. for about 5 minutes. After that, annealing was performed in an oxidizing atmosphere for about 10 minutes under an oxygen pressure of about 200 Torr without exposing to the atmosphere. The operations of the film forming step and the annealing step were both repeated 12 times and repeated twice. The total thickness of the dielectric films was about 100 nm. Next, platinum was formed on each of them as an upper electrode to a thickness of about 100 nm to obtain capacitors. Obtained in this example,
Table 11 shows the capacitor characteristics of the capacitors. As a comparative example, Table 11 also shows the characteristics of capacitors when a film is formed at a substrate temperature of about 600 ° C. for about 60 minutes. It is clear that the leak current is reduced in this embodiment. The effect of the present invention is that the film formation step and the heat treatment step are at least 2
It may be more than 30 times, but is preferably 30 times or less in order not to reduce the throughput of the capacitor film forming process. Furthermore, 10 to 20 times is most preferable. There is no limitation on the thickness of the film formed at one time, but it is usually 5 to 10 nm.

[0058]

[Table 11] [Embodiment 13] FIG. 8 is a schematic sectional view of an embodiment of an apparatus for manufacturing a dielectric film according to the present invention. 14 is a vacuum chamber made of stainless steel. Reference numeral 15 is a region having a mechanism for forming a dielectric film, and 16 is a region having a mechanism capable of performing heat treatment in an oxidizing atmosphere. In FIG. 8, 17
Is a substrate, 18 is a sputtering target, and 19 is a heater for heating the substrate. Reference numeral 20 is a nozzle for introducing an oxidizing gas. Reference numeral 21 is a mechanism for rotating the substrate. The substrate 17 is first formed in the dielectric film forming region 15 and then immediately rotated by the substrate rotating mechanism 21 to the heat treatment region 16 for heat treatment. The series of film forming steps and the heat treatment step in an oxidizing atmosphere can be performed a predetermined number of times. The film forming condition and the heat treatment condition are controlled by a control device (not shown) so that the temperature, time, gas partial pressure, and gas composition are set to predetermined conditions. In this embodiment, a sputtering apparatus is used as the film forming mechanism, but when using a CVD apparatus, as shown in FIG. 9, a source gas nozzle 30 is provided in the film forming region to supply the source gas from the source gas supply system 29. The same can be done by supplying. When an MBE apparatus is used, the same can be done by providing a metal evaporation source 31 and a shutter 32 on the surface of the substrate and forming a film by a normal MBE method as shown in FIG. Further, in the case of laser ablation, FIG.
As shown in FIG. 7, the same effect as that of the present embodiment can be obtained by condensing the laser light from the laser light source 33 with the lens 35 through the slit 34 and performing the sputtering while rotating the target 18 with the target rotating mechanism 36. That is clear.

[Embodiment 14] FIG. 12 is a schematic sectional view of another embodiment of the dielectric film manufacturing apparatus according to the present invention. 22
Is a vacuum chamber made of stainless steel. Reference numeral 23 is an area provided with a mechanism for forming a dielectric film. Reference numeral 24 is an area provided with a high-pressure heat treatment mechanism. In FIG. 12, 17 is a substrate, 18 is a sputter target, and 19 is a heater for heating the substrate. Reference numeral 21 is a mechanism for rotating the substrate. The substrate 17 is first formed into a film in the film forming region 23, and then immediately rotated by the rotating mechanism 21 to the high-pressure heat treatment region 24. High-pressure heat treatment area 24 is hydraulically driven 2
It is brought into close contact with the substrate support mechanism by 5. The oxidizing gas is pressurized by the compressor 26 and is supplied to the pressurizing chamber through the gas nozzle. In this way, the dielectric film is heat-treated under a pressure not lower than atmospheric pressure. Deposition conditions and heat treatment conditions are controlled by a controller (not shown) such as temperature, time, gas partial pressure,
The gas composition is controlled so as to meet a predetermined condition. Although the sputtering method is used as the film forming mechanism in this embodiment, the CV is used as the film forming mechanism as in the thirteenth embodiment.
It is clear that the same effects as in this embodiment can be obtained by D, MBE and laser ablation.

[Embodiment 15] The dielectric film of the capacitor is R
Since it is produced by the F magnetron sputtering method, (Ba
_1-x Sr _x ) TiO ₃ , of the composition represented by the composition formula of 0 ≦ x ≦ 1, Mn ₂ O ₃ is 1.5 wt% at x = 0.75.
A sputtering target having the following composition was produced. As a raw material, the raw materials were barium carbonate (BaCO ₃ ) and strontium carbonate (Sr) each having a purity of 99.9%.
CO ₃ ), titanium oxide (TiO ₂ ), and dimanganese trioxide (Mn ₂ O ₃ ) powders were used, and alcohol wet ball mill mixing using zirconia balls so as to have a desired composition was carried out for 12 hours. The product was taken out, dried, press-molded at a pressure of about 0.5 ton / cm ² , and then calcined at about 1200 ° C. for about 2 hours in the atmosphere. The reaction product was roughly crushed for about 1 hour using a ladle mill, and then wet crushed for about 20 hours using a ball mill in the same manner as during the mixing. After taking out and drying, press-molding is carried out at about 0.5 ton / cm ² so as to form a disk shape with a diameter of about 4 inches after sintering, and it is sintered at about 1350 ° C. for about 3 hours in an oxygen atmosphere. I went. The sintered body was ground to a thickness of about 5 mm to obtain a target.

A sputtered film was produced under the following conditions using the produced target. As a substrate, a 3-inch silicon wafer substrate on which a Pt lower electrode having a thickness of 200 nm was formed by a sputtering method was used. The dielectric film of the capacitor having the above composition has an atmosphere of O ₂ 50%, A
r50%, pressure about 30 mTorr, substrate temperature about 600
A dielectric film for a capacitor having a film thickness of 80 nm was formed at a temperature of about 200 W, a sputtering power of about 200 W and a sputtering time of about 15 minutes. For the evaluation of electric characteristics, a Pt upper electrode having a diameter of 1 mm or 0.5 mm was formed on the dielectric film of the capacitor by a sputtering method.

The content of Mn ₂ O ₃ added is 0.03 wt%,
0.05wt%, 3.00wt%, 5.00wt%,
In the case of 5.50 wt%, a sample for electrical characteristic evaluation was prepared under the same conditions as in the above-described preparation method. The film thicknesses at this time were all between 79 and 81 nm.

For comparison, a sample for evaluating a dielectric film of a conventional capacitor in which Mn ₂ O ₃ was not added was prepared in the same manner as above. The film thickness was about 82 nm.

Table 12 shows the measurement results of the silicon oxide equivalent film thickness and the leakage current density (when 2V is applied) of the dielectric films of these prototype capacitors at room temperature.

As a sputtering target, a method of compacting powder on a metallic dish such as copper in the state of powder before sintering, which has been subjected to calcination reaction and crushing, to obtain a target can also be used. Although the film formation rate is lower than that of the dense sintered body target, a similar dielectric film of a capacitor can be obtained by increasing the sputtering time.

[0066]

[Table 12] As shown in Table 12, Mn ₂ O ₃ is added from 0.05 to 5.00.
It was found that the leakage current density of the dielectric film of the capacitor containing the addition of wt% is reduced to 6 × 10 ⁻⁸ A / cm ² or less at room temperature, which is a practical requirement from the refresh time of DRAM.

When the content of Mn ₂ O ₃ is less than 0.05 wt% or exceeds 5.00 wt%, there is almost no improvement as compared with when it is not contained, or rather the leakage current density increases.

Although the case of x = 0.75 is shown here, it is confirmed that the same effect of addition addition of Mn ₂ O ₃ is obtained for any value of x of 0 ≦ x ≦ 1. It was

Example 16 Pb (Zr _1-y Ti _y ).
Of the compositions represented by O ₃ and 0 ≦ y ≦ 1, y =
At 0.48, a sputtering target having a composition in which 1.5 wt% of Mn ₂ O ₃ was added was prepared.
99.9% purity as a raw material for target production
Lead oxide (PbO), zirconium oxide (ZrO ₂ ),
Titanium oxide (TiO ₂ ), dimanganese trioxide (Mn
₂ O ₃ ) powder was used. At this time, the composition of lead, which is an element that re-evaporates significantly during sputtering, was increased by 20% from the stoichiometric ratio so that the film composition became the stoichiometric ratio.

Targets were produced under the same conditions as in Example 15 except that the calcination reaction temperature was about 950 ° C. and the sintering temperature was about 1250 ° C.

Using the above target, a dielectric film for a capacitor was formed under the same substrate and conditions as in Example 15. The film thickness at this time was about 120 nm.

The addition content of Mn ₂ O ₃ is 0.03 wt%,
0.05wt%, 3.00wt%, 5.00wt%,
In the case of 5.50 wt%, a sample for electrical characteristic evaluation was prepared under the same conditions as in the above-mentioned preparation method. The film thicknesses at this time were all between 118 and 122 nm.

For comparison, a sample for evaluating a dielectric film of a conventional capacitor in which Mn ₂ O ₃ was not added was prepared in the same manner as above. The film thickness was about 135 nm.

Table 13 shows the measurement results of the silicon oxide-equivalent film thickness and the leakage current density (when 2 V is applied) of these manufactured capacitor films at room temperature.

[0075]

[Table 13] As shown in Table 13, the dielectric film of the capacitor containing Mn ₂ O ₃ added in an amount of 0.05 wt% to 5.00 wt% has a leakage current density at room temperature which is a practical requirement from the refresh time of DRAM. It was found to be reduced to 6 × 10 ⁻⁸ A / cm ² or less.

If the Mn ₂ O ₃ content is less than 0.05 wt% or exceeds 5.00 wt%, there is almost no improvement, or the leakage current density increases.

Although the case of y = 0.48 is shown here, the same M value is obtained for any y value of 0 ≦ y ≦ 1.
It was confirmed that the effect of adding n ₂ O ₃ was included.

[Example 17] Even when 2 to 15 mol% of lead was replaced with Sr, strontium carbonate (SrC) was used as a raw material for the Sr element of the sputtering target.
O ₃ ) powder was used and carried out under the same conditions as described in Example 16. Tables 14, 15, and 16 show the results when 2 mol%, 10 mol%, and 15 mol% of lead were replaced with Sr, respectively.

[0079]

[Table 14]

[0080]

[Table 15]

[0081]

[Table 16] As shown in Tables 14, 15 and 16, 0.05 w of Mn ₂ O ₃ was added.
It has been found that the leakage current density is reduced in the capacitor film containing t to 5.00 wt% added.

When the content of Mn ₂ O ₃ is less than 0.05 wt% or exceeds 5.00 wt%, there is almost no improvement as compared with the case where no Mn ₂ O ₃ is contained, or rather the leakage current density increases. Further, by replacing lead with Sr element, the relative dielectric constant increases and the silicon oxide equivalent film thickness decreases, but the leakage current density tends to increase. By adding Mn element, the leakage current density decreases. The utility can be increased.

Here, if the substitution amount of the Sr element is less than 2 mol%, the degree of improvement of the relative dielectric constant is small, and it is 15 mo.
When it exceeds 1%, the leakage current density becomes large and the practical advantage is lost.

Further, here, when y = 0.48, the substitution amount of Sr with respect to Pb was 2 mol%, 10 mol%, 15 mo.
In the case of 1%, any y value of 0 ≦ y ≦ 1 is obtained, and at the same time, 2 mol% to 15 mol% of Sr
It was confirmed that the same effect of adding Mn ₂ O ₃ was obtained for any of the values.

[0085] [Example _{18] (Sr 1-z Ca} z) 3 Ti 2 O
₇ , of the composition represented by 0.40 ≦ z ≦ 0.80, z
A sputtering target having a composition of = 0.50 was prepared. The manufacturing method is 9
Using 9.9% strontium carbonate (SrCO ₃ ), calcium carbonate (CaCO ₃ ) and titanium oxide (TiO ₂ ) powder, alcohol wet ball mill mixing using zirconia balls to obtain a desired composition was performed for 15 hours. Carried out. After taking out and drying, about 0.4 ton / c
After press forming with a pressure of m ² , about 1150 in air
A calcination reaction was carried out at ℃ for 3 hours. The reaction product was roughly crushed for about one and a half hours with a raker, and then wet crushed with a ball mill for about 20 hours in the same manner as during the mixing. take out,
After drying, press-molding was performed at a rate of 0.7 ton / cm ² so as to form a disk with a diameter of about 4 inches after sintering, and about 1
Sintering was performed in an oxygen atmosphere at 550 ° C. for about 4 hours. The sintered body was ground to a thickness of about 5 mm to obtain a target.

A sputtered film was produced under the following conditions using the produced target. As a substrate, a 3-inch silicon wafer substrate on which a Pt lower electrode having a thickness of about 200 nm was formed by a sputtering method was used. The capacitor film of the composition has an atmosphere of O ₂ 50%, Ar 50
%, A pressure of about 30 mTorr, a substrate temperature of about 600 ° C., a sputtering power of about 200 W, and a sputtering time of about 15 minutes to form a dielectric film of a capacitor having a thickness of about 40 mm. For the evaluation of electrical characteristics, an upper electrode made of Pt having a diameter of about 1 mm or about 0.5 mm was formed on the capacitor film by a sputtering method. z = 0.35, 0.40, 0.45,
0.55, 0.60, 0.65, 0.70, 0.75,
In the case of 0.80 and 0.85, samples for measuring electric characteristics were prepared in the same manner. All film thicknesses were between 39 and 41 nm.

Table 17 shows the measurement results of the silicon oxide-equivalent film thickness and the leakage current density (when 2 V is applied) of the dielectric film of these prototype capacitors at room temperature.

[0088]

[Table 17] As shown in Table 17, when 0.40 ≦ z ≦ 0.80, the relative permittivity is large and high insulation is exhibited, and the silicon oxide film equivalent film thickness and the leakage current density are changed from the DRAM refresh time, respectively. It can be reduced to 6 × 10 ⁻⁸ A / cm ² or less at room temperature when the converted film thickness is 1.5 nm or less, which is a practical requirement.

According to the present embodiment, as the density of DRAM becomes higher, the requirement that the dielectric film of the capacitor also be made thinner can be met for morphological reasons. That is, because the material is excellent in insulation,
Even if the film thickness is reduced (at this time, the silicon oxide equivalent film thickness is naturally reduced), the state in which the leakage current density is small can be realized.

[Example 19] As a raw material for a sputtering target of each additive element of La, Nb, Sm, and Gd, La ₂ O ₃ , Nb ₂ O ₃ , Sm ₂ O ₃ , and Gd having a purity of 99.9% were used. ₂
O ₃ powder was used. Target production conditions and sputtering conditions during film formation were almost the same as in Example 17. Here, (Sr _1-z Ca _z ) _{3 of} Example 18
In the case of z = 0.50 of Ti ₂ O ₇ , La ₂ O ₃ ,
The electrical characteristics of the addition effects of Nb ₂ O ₃ , Sm ₂ O ₃ , and Gd ₂ O ₃ are shown in Table 18, Table 19, Table 20, and Table 21, respectively. The film thickness at this time was about 41 nm.

[0091]

[Table 18]

[0092]

[Table 19]

[0093]

[Table 20]

[0094]

[Table 21] As shown in Table 18, Table 19, Table 20, and Table 21, by adding La ₂ O ₃ , Nb ₂ O ₃ , Sm ₂ O ₃ , and Gd ₂ O ₃ as an additive, Can be achieved (due to the improvement of the relative dielectric constant). That is, by adding an additive to a material having excellent insulating properties, the dielectric constant can be increased and a composite effect can be obtained. In this case, if it is less than 0.05 mol%, the silicon oxide conversion film thickness is not so much improved, and
If the amount added exceeds mol%, the leakage current density increases, so that the advantage as a dielectric film of a capacitor cannot be obtained.

[Embodiment 20] A dielectric film for a capacitor was formed by sputtering in the same manner as that described in Embodiment 19. The film thickness at this time is about 41 nm.
Met. In _{(Sr 1-z Ca z)} 3 Ti 2 O 7 z =
0.50 to which ₃ mol% La ₂ O ₃ and 5 m
The results of the electrical characteristics of the dielectric film of the capacitor in which Mn ₂ O ₃ was added to the composition containing ol% (corresponding to the materials of Sample 3 and Sample 4 in Table 18, respectively) are shown. 22 and Table 23.

[0096]

[Table 22]

[0097]

[Table 23] As shown in Tables 22 and 23, the leakage current density is remarkably improved by the addition content of Mn ₂ O ₃ . Where Mn ₂
If the amount of O ₃ added is less than 0.05 wt%, no sufficient effect can be seen in reducing the leakage current density. In addition, Mn ₂
If the amount of O ₃ added exceeds 5.00 wt%, the leakage current density rather increases greatly.

[0098]

As described above, according to the present invention, the protective film formed on the upper electrode film suppresses the oxygen deficiency of the high dielectric constant dielectric film during the process and prevents the deterioration of the capacitor characteristics. It can be prevented. Therefore, a capacitor having high characteristics can be obtained in a small area, and further high integration of a semiconductor memory device or the like can be achieved.

Further, after the film formation process is stopped, oxygen that has been lost can be compensated by gradual cooling in an oxidizing atmosphere, heat treatment in a high-pressure oxidizing atmosphere after film formation, or heat treatment after forming the upper electrode. A dielectric film having excellent capacitor characteristics can be obtained.

Further, by repeating the film forming process and the heat treatment process continuously and plural times in one vacuum chamber, it is possible to obtain a dielectric film having good capacitor characteristics with few oxygen vacancies.

SrTiO ₃ system, PZT system, (Sr, C
a) Leakage current can be reduced by adding a trace amount of Mn element to the ₃ Ti ₂ O ₇ based dielectric material. (S
Leakage current can be reduced by incorporating a small amount of lanthanum element in the r, Ca) ₃ Ti ₂ O ₇ based dielectric material.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view of the structure of an embodiment of a capacitor of the present invention.

FIG. 2 is an explanatory cross-sectional view of a capacitor structure of Example 5.

FIG. 3 is a cross-sectional explanatory diagram of a capacitor structure according to a sixth embodiment.

FIG. 4 is a cross-sectional explanatory diagram of a capacitor structure according to a seventh embodiment.

FIG. 5 is an explanatory cross-sectional view of a capacitor structure of Example 8.

FIG. 6 is a diagram showing changes in the relative dielectric constant of the dielectric film of Example 8 with temperature.

FIG. 7 is an explanatory cross-sectional view of the capacitor structure of Example 9.

FIG. 8 is a cross-sectional explanatory view of a dielectric film forming apparatus of Example 13.

FIG. 9 is a cross-sectional explanatory view of another example of the dielectric film forming apparatus according to the thirteenth embodiment.

FIG. 10 is a cross-sectional explanatory view of still another example of the dielectric film forming apparatus according to the thirteenth embodiment.

FIG. 11 is a sectional explanatory view of still another example of the dielectric film forming apparatus of the thirteenth embodiment.

FIG. 12 is a cross-sectional explanatory view of a dielectric film forming apparatus of Example 14;

[Explanation of symbols]

 1 Protective film 3 Lower electrode 4 Dielectric film 5 Upper electrode

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shinichi Kinouchi 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Material Devices Research Laboratory (72) Inventor Hideoki Uchikawa 8-1-1 Tsukaguchihonmachi, Amagasaki Mitsubishi Electric Corporation Material Device Research Center (72) Inventor Hisao Watai 8-1-1 Tsukaguchi Honmachi, Amagasaki City Mitsubishi Electric Corporation Material Device Research Institute (72) Inventor Noboru Mikami 8-1-1 Tsukaguchi Honcho, Amagasaki City No. Mitsubishi Electric Corporation Material Devices Research Laboratory (72) Inventor Go Horikawa 8-1-1 Tsukaguchi Honcho, Amagasaki City Mitsubishi Electric Corporation Material Devices Research Laboratory (72) Inventor Tomohito Okuhira 4-Mizuhara Itami City Mitsubishi Electric Incorporated LSE Research Institute (72) Inventor Yoshihiro Kusumi 8 Tsukaguchi Honcho, Amagasaki City Chome 1-1 No. 1 Central Research Laboratory, Mitsubishi Electric Corporation

Claims (16)

[Claims] 1. A high dielectric constant capacitor comprising a dielectric film made of a high dielectric constant dielectric material containing a metal oxide as a main component, and a pair of electrodes facing each other with the dielectric film sandwiched therebetween. A high dielectric constant capacitor comprising a protective film for suppressing oxygen deficiency of the dielectric material formed on an upper electrode formed on the dielectric film. 2. The material of the protective film is (a) Ti, A
l, W, Mo, Ta, Nb, V, Cr, Zr and Ga
(B) Ti, Al, Ta, Nb, Zr, Re, Mg of at least one metal selected from the group consisting of
And (c) Ti, W, Pt, Mo, Ta, N, an oxide of at least one metal selected from the group consisting of
a silicate of at least one metal selected from the group consisting of b, V, Cr, Zr and Co, and (d) T
The high dielectric constant capacitor according to claim 1, wherein the high dielectric constant capacitor is made of at least one metal selected from the group consisting of i, W, Ta, Cu, Ge, Ni and Cr, or an alloy thereof. . 3. The high dielectric constant capacitor according to claim 1, wherein the protective film is formed by laminating at least two kinds of materials according to claim 2. 4. A capacitor of a semiconductor memory device comprising a dielectric film made of a dielectric material containing a metal oxide as a main component, and a pair of electrodes facing each other with the dielectric film interposed therebetween. Is a high dielectric constant capacitor composed of a laminated film of two or more kinds of dielectric materials. 5. A method of manufacturing a capacitor of a semiconductor memory device, comprising: providing a dielectric film made of a dielectric material containing a metal oxide as a main component on a lower electrode, and providing an upper electrode on the dielectric film. A method for manufacturing a capacitor, comprising: after forming the dielectric film, cooling the dielectric film in an oxidizing atmosphere at a rate of 15 ° C./minute or less. 6. A method of manufacturing a capacitor of a semiconductor memory device, comprising: providing a dielectric film made of a dielectric material containing a metal oxide as a main component on a lower electrode, and providing an upper electrode on the dielectric film. A method for manufacturing a capacitor, comprising forming an upper electrode on the dielectric film, and then performing heat treatment in an oxidizing atmosphere. 7. A method of manufacturing a capacitor of a semiconductor memory device, comprising: providing a dielectric film made of a dielectric material containing a metal oxide as a main component on a lower electrode, and providing an upper electrode on the dielectric film. After the dielectric film is formed, a heat treatment is performed in an oxidizing atmosphere in which the partial pressure of the oxidizing gas is 1 atm or more, and a method for manufacturing a capacitor. 8. A method of manufacturing a capacitor of a semiconductor memory device, comprising: providing a dielectric film made of a dielectric material containing a metal oxide as a main component on a lower electrode, and providing an upper electrode on the dielectric film. A method for manufacturing a capacitor, characterized in that the step of forming the dielectric film and the step of performing heat treatment in an oxidizing atmosphere that is continuous with the step of forming the dielectric film are repeated at least twice to provide a dielectric film having a predetermined thickness. 9. A dielectric film manufacturing apparatus in which a film forming mechanism, a heat treatment mechanism in an oxidizing atmosphere, and a substrate supporting mechanism including a substrate heating device are installed in one vacuum chamber. 10. The heat treatment mechanism in the oxidizing atmosphere comprises:
10. The dielectric film manufacturing apparatus according to claim 9, wherein the pressure can be raised to 1 atm or more. 11. (Ba _1-x Sr _x ) TiO ₃ , 0 ≦ x ≦
In the composition represented by the composition formula 1, the Mn element is added to the oxide M.
A dielectric film for a capacitor, which contains 0.05 to 5 wt% of n ₂ O _{3 as} a molecular formula. 12. Pb (Zr _1-y Ti _y ) O ₃ , 0 ≦ y ≦
In the composition represented by the composition 1, the Mn element is added to the oxide Mn.
_A dielectric film for a capacitor, which contains 0.05 wt% to 5 wt% of a molecular formula of ₂ O ₃ . 13. A dielectric film for a capacitor, wherein 2 to 15 mol% of the Pb element in the composition according to claim 12 is replaced with Sr. 14. A dielectric film for a capacitor, wherein a composition represented by a composition formula (Sr ₁ -z _Caz ) ₃ Ti ₂ O _{7 has} a composition of 0.4 ≦ z ≦ 0.8. . 15. _{(Sr 1-z Ca z)} 3 Ti 2 O 7, 0.4
Me ₂ O is added to the composition represented by ≦ z ≦ 0.8.
_{3 A} dielectric film for a capacitor, which is obtained by adding 0.05 to 5 mol% of an oxide represented by a composition formula (Me represents La, Nd, Sm, or Gd). 16. The material according to claim 15, further comprising Mn
Element is Mn ₂ O ₃ molecular formula from 0.05 wt% to 5 wt%
A dielectric film for a capacitor, which is added and contained.