JPH10135233A - Method of reforming high-dielectric const. film and heat-treating apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bury a metal oxide high-dielectric const. film in holes formed due to oxygen lack and oxidation of C and H atoms, impurity in the film originating from a film forming gas, by a low-temp., little-damage and short-time heat treatment. SOLUTION: A gas, contg. O3 at its partial pressure over the atmospheric pressure is introduced into a high-pressure chamber 1, and a wafer W set in a stage 3 is heated by a heater 4, while an ultraviolet ray hν is fed into the chamber from an ultraviolet lamp 7 through an optical fiber 6 directed to the end face of the wafer, to optically decompose O3 near the wafer to create O-type active species. On the wafer W a high-dielectric contg. film is formed as a capacitor insulating film for DRAM. The heating tamp. is far lower than the durable temp. of a metal layer electrode of a capacitor. If the treating time is short, the active species can be efficiently penetrated at a high pressure to raise the specific dielectric const. ε of the film and lower the leak current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modification method for reducing a leak current of a high dielectric constant film suitable for use as a capacitor insulating film of a DRAM, and a heat treatment apparatus suitably used for the method.

[0002]

2. Description of the Related Art Memory devices such as DRAM and SRAM are
Although semiconductor devices are particularly advanced in miniaturization, in order to keep the soft error rate low and ensure reliability, the capacitor capacity per bit, that is, per memory cell, must be fixed. Value (about 30f
F) It is necessary to secure more than this. Conventionally, a capacitor area is secured by adopting a three-dimensional structure such as a cylindrical type or a multi-stage fin type.
This problem has been solved by using an ixNy film or a SiOx / SixNy laminated film. The SixNy film is
Although the relative dielectric constant [epsilon] is about 4 to 7, it is easy to use because it has a high withstand voltage and can be made thinner. However, as described above, a complex three-dimensional structure having a high aspect ratio has an extremely heavy burden on flattening an interlayer insulating film, and from the viewpoint of reducing leakage current, thinning of a capacitor insulating film is approaching its limit. Therefore, 256
In the generations of MDRAM and 1GDRAM, new technological breakthroughs are required.

Against this background, a high dielectric constant film is expected to be a promising material for a capacitor insulating film. As the high dielectric constant film, Ta ₂ O ₅ (tantalum oxide: ε = 20 to
35) In addition, composite oxide ceramics exhibiting paraelectric, piezoelectric, and pyroelectric properties due to a perovskite-type unit crystal lattice structure are known. Representative examples of such composite oxide ceramics include BST (barium strontium titanate: ε> 400) and PZT (lead zirconate titanate: ε> 1000). If these high dielectric constant films are used as capacitor insulating films, it is possible to secure a sufficient capacity even with a planar capacitor structure, which facilitates device manufacture and improves device reliability. be able to.

In general, vacancies due to oxygen atom vacancies tend to occur in a thin film of a metal oxide, and the leakage current resistance is often deteriorated as compared with the case where there are no vacancies. Further, since atoms and molecules constituting the high dielectric constant film have a low vapor pressure, for example, when these are to be formed by CVD, an organometallic compound is used as a source gas. For example, a Ta ₂ O ₅ film is made of Ta (OC ₂ H ₅ )
₅ can be formed by MOCVD. Further, Pb (C ₂ H ₅ ) ₄ , Zr
_{(C 11 H 19 O 2)} 4, Ti (i-OC 3 H 7) 4 and the like of the gas is used. However, C atoms and H atoms derived from the source gas are inevitably taken into the metal oxide film formed as described above as impurities.

[0005] Journal of Electrochemical
Society Vol.143, No.3 (1996) (J. Elctroch)
em. Soc., Vol. 143, No. 3, March 1996) includes Ta (O
Ta ₂ O formed by MOCVD using C ₂ H ₅ ) _5
The results of a detailed study of the leakage current generation mechanism for the _five films are described. According to this document, in an amorphous Ta ₂ O ₅ film, a Frenkel-Pool type conduction caused by impurities such as C atoms and H atoms forms a main part of a leak current. This leak current has a pressure of 0.5 To
heat treatment at 700 ° C. for 10 minutes in an rr O ₂ atmosphere, or a pressure of 0.3 Torr and an RF power of 0.35 W / c
m ² (RF frequency = 13.56 MHz), 400 ° C, 1
It is significantly reduced by the O ₂ plasma treatment for 0 minutes. Ta ₂ after the above heat treatment or plasma treatment
From the results of the secondary ion mass spectrometry of the O ₅ film, O atoms in the atmosphere diffuse in the film to oxidize C atoms and H atoms,
It has been confirmed that the a atom is also oxidized.

[0006]

However, when oxidizing C atoms and H atoms, which are impurities in the film, 700 ° C.
Performing the heat treatment in a very high temperature range is not desirable for the device. This is related to the fact that a capacitor using a high-dielectric-constant film as an insulating film usually has an MIM structure (laminated structure of a metal upper electrode-insulator-metal lower electrode). That is, since the high-dielectric-constant film is formed at a high temperature, if this film is formed directly on a lower electrode such as a polysilicon film, Si diffuses into the high-dielectric-constant film,
Frenkel-Pool current flows due to the impurity level formed by The surface of the polysilicon lower electrode is nitrided to prevent Si diffusion, and the capacitor may have a MIS type structure (laminated structure of a metal upper electrode-insulator-semiconductor lower electrode), but the MIM type structure has a higher series resistance. Is low and the operation speed can be increased. For this reason, a metal material such as Pt, Ir, and Ru is required for the lower electrode, and a barrier metal such as TiN is required accordingly.

However, since the upper limit of the heat resistance of the barrier metal is about 700 ° C., the MIM structure cannot be adopted on the premise of the above-described high-temperature heat treatment. On the other hand, if the temperature is to be lowered to about 400 ° C., the heat treatment takes as long as 30 minutes, resulting in a significant decrease in throughput.

In this regard, since the plasma processing can be performed at about 400 ° C., there is no problem in employing the MIM type structure. However, there is a high possibility that metal atoms will be released from the wall of the plasma chamber or the surface of the discharge electrode during plasma discharge, and that metal ions will be contaminated, or impact damage will be caused by accelerated ions in the plasma. It is not necessarily suitable as a method for modifying a capacitor insulating film which is becoming thinner and thinner as the semiconductor device becomes thinner. Therefore, an object of the present invention is to provide a method and an apparatus capable of modifying a high dielectric constant film at low temperature, with low damage and in a short time.

[0009]

According to the present invention, when oxidizing a high-dielectric-constant film made of a metal oxide, the concentration of oxygen-based active species in the immediate vicinity of the high-dielectric-constant film is increased more than before. The above object is achieved. There are two methods for making this possible: (a) a method in which the oxygen-based active species is brought into contact with the high dielectric constant film in the gas phase, and (b) a method in which the contact is performed in the liquid phase.

In the method (a), a high-dielectric-constant film made of a metal oxide is heat-treated in an atmosphere containing a gas capable of generating an oxygen-based active species at a partial pressure of at least 1 atm or at a total pressure. I do. This heat treatment may be performed while irradiating the high dielectric constant film with ultraviolet rays. In the method (b), a liquid capable of generating oxygen-based active species by thermal decomposition is brought into contact.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the above method (a), if heat treatment is performed in an atmosphere containing a gas capable of producing oxygen-based active species at a partial pressure of at least 1 atm or a total pressure,
Even if the heat treatment temperature is lower than before and the heat treatment time is shorter, high-concentration oxygen can be diffused into the oxide film. Therefore, even if the film is formed using an organometallic compound, even if the film has a high dielectric constant containing C atoms or H atoms as impurities in the film, the impurities in the film can be efficiently oxidized to reduce the leak current. Becomes possible.

The high dielectric constant film subjected to the modification treatment in the present invention includes Ta ₂ O ₅ , PbTiO ₃ (lead titanate), B
aTiO ₃ (barium titanate), Bi ₄ Ti ₃ O
₁₂ (bismuth titanate), BST (barium titanate
Strontium), STO (strontium titanate), PZT (lead zirconate titanate), PLZT (lead lanthanum zirconate titanate), and SBT (strontium bismuth tantalate) can be exemplified.

The gas capable of producing the oxygen-based active species is as follows:
Of course, it may be used alone, or may be used as a mixture with a rare gas such as He or Ar. The total pressure in the case of using the gas alone or the partial pressure in the case of using the gas in a mixture is preferably set in the range of about 3 atm or more and 700 atm or less. In a pressure range lower than 3 atm, a sufficient oxygen diffusion rate may not be obtained depending on a combination with a heating temperature. On the other hand, in a pressure range higher than 700 atmospheres, a pressurizing device having a high capacity and a container having a high pressure resistance are required, and there is a great possibility that cost performance may be reduced. As the above gas, O ₃ can be typically used.

The above method (a) can be performed by using, for example, a high-pressure heat treatment apparatus as shown in FIG.
The apparatus includes a stage 13 for mounting a wafer W inside a cylindrical high-pressure chamber 11 made of stainless steel.
Is housed. An exhaust port 12 is provided on the bottom side of the high-pressure chamber 11, and the inside thereof is exhausted by an exhaust device (not shown) connected in the direction of arrow A as necessary. On the other hand, a gas introduction pipe 15 is inserted through the ceiling of the high-pressure chamber 11 so that a gas capable of generating oxygen-based active species is introduced from the direction of arrow B by a pressurizing device (not shown). Further, the stage 13 has a built-in heater 14.
The high-permittivity film on the wafer W is heated by the heat conduction through.

FIG. 1 shows an apparatus according to the present invention in which the generation of oxygen active species is promoted by combining heating under a pressurized atmosphere with ultraviolet irradiation. In this apparatus, a stage 3 for mounting a wafer W in a cylindrical high-pressure chamber 1 is accommodated. An exhaust port 2 is provided on the bottom side of the low-pressure chamber 1, and the inside thereof is exhausted by an exhaust device (not shown) connected in the direction of arrow A as necessary. On the other hand, a gas introduction pipe 5 is inserted into the ceiling side of the high-pressure chamber 1 so that a gas capable of generating oxygen-based active species can be introduced from the direction of arrow B by a pressurizing device (not shown). Further, the stage 3 has a built-in heater 4 for heating the high dielectric constant film on the wafer W by heat conduction through the stage 3.

However, the greatest feature of this apparatus is that a bundle of optical fibers 6 is inserted into the ceiling of the high-pressure chamber 1 and the end faces of the bundle are opposed to each other in the vicinity of the wafer W surface. The point is that the wafer surface can be irradiated with ultraviolet light hν which is directly incident from the ultraviolet lamp 7 or reflected by the reflecting mirror 8 and incident. Here, the distance between the end face of the optical fiber 6 and the wafer surface was about 10 mm here. The reason that the end face of the optical fiber 6 is brought close to the surface of the wafer W in this way is to prevent oxygen-based active species due to O ₃ photolysis from being deactivated before reaching the wafer surface as much as possible, and to efficiently activate the active species. This is to make available. As the ultraviolet lamp 7, for example, a deuterium lamp, an ultra-high pressure mercury xenon lamp, a low pressure mercury lamp, and a metal halide lamp can be used. Alternatively, an excimer laser light source may be used. In particular, for a gas having a so-called wavelength effect in which a generated chemical species changes depending on the excitation wavelength, it is necessary to select a wavelength according to a desired chemical species. The installation positions of the optical fiber 6 and the ultraviolet lamp 7 are not limited to the ceiling side of the high-pressure chamber 1 as long as the ultraviolet light can be guided toward the wafer W. With this configuration, high-pressure heat treatment and ultraviolet irradiation can be performed, and the modification effect and the modification efficiency of the high dielectric film can be significantly increased.

On the other hand, according to the above method (b), if a liquid capable of generating an oxygen-based active species by thermal decomposition is brought into contact, the high dielectric constant film has a high concentration even at atmospheric pressure or under reduced pressure. As a result, it is possible to come into contact with the oxygen-based active species, and it is also possible to efficiently oxidize impurities in the film. The method (b) can be classified into (b-1) a method of contacting in an aerosol state and (b-2) a method of contacting in a liquid film state, depending on the form of liquid contact.

In the contact method in the aerosol state (b-1), the aerosol is continuously supplied from the vicinity of the high dielectric constant film maintained at a predetermined heating temperature.
The aerosol particles attached to the membrane surface are immediately pyrolyzed,
Oxygen-based active species can be generated. FIG. 3 shows a configuration example of a heat treatment apparatus used for heat treatment in a low-pressure mist atmosphere. This device comprises a cylindrical low pressure chamber 21
, A stage 23 for mounting the wafer W and a shower head 25a for supplying the mist M of the oxidizing chemical liquid L are arranged to face each other. The internal atmosphere of the low-pressure chamber 21 is adjusted to a predetermined pressure determined by the exhaust speed performed in the direction of arrow A through the exhaust port 22 and the flow rate of the mist emitted from the shower head 25a.

The mist M is generated by the vaporizer I. In the vaporizer I, an inert carrier gas is blown into the oxidizing chemical liquid L filled in the closed container 27 through the carrier gas supply pipe 30, and mist M is generated by bubbling. The oxidizing chemical liquid L is supplied from an oxidizing chemical storage tank 28, and the carrier gas is supplied from a carrier gas cylinder 29. Here, the former is exemplified by H ₂ O ₂ and the latter by N ₂ .
The generated mist M is supplied into the low-pressure chamber 21 through the mist supply pipe 25. The flow path between the mist M and the mist M may be covered with a heat insulating material in order to prevent aggregation of the mist M due to cooling. In FIG. 3, the heater 26 is attached to the shower head 25a.
Is also built in to prevent mist M from aggregating.

When the oxidizing chemical L is a chemical that is decomposed by irradiation with ultraviolet rays to generate oxygen-based active species, an ultraviolet irradiation means may be added to the low-pressure chamber 21. For example, a configuration may be adopted in which a quartz window is provided on the side wall surface of the low-pressure chamber 21 and the space between the shower head 25a and the wafer W is irradiated with ultraviolet rays from the lateral direction. The generation of the mist M is not limited to bubbling as described above, and the oxidizing chemical liquid L may be vaporized using, for example, an ultrasonic vibrator.

On the other hand, when the contact is made in a liquid state as in (b-2), for example, a liquid film of a resist developing solution is formed on a wafer in paddle development and left for a while, It is preferable to hold the liquid on the high dielectric constant film by the surface tension of the liquid itself. However,
If the high-dielectric-constant film is heated from the beginning, the liquid evaporates immediately, so the heating is performed after the formation of the liquid film. The heating in this case is conveniently performed, for example, by lamp heating from above the liquid film. As the liquid, aqueous hydrogen peroxide can be typically used.

FIG. 4 shows a configuration example of a heat treatment apparatus suitable for use in the method (b-2). In this apparatus, a stage 33 for mounting a wafer W inside a low pressure chamber 31 having a cylindrical shape is accommodated. An exhaust port 32 is provided on the bottom side of the low-pressure chamber 31, and the inside thereof is exhausted by an exhaust device (not shown) connected in the direction of arrow A as necessary. The side wall surface and the bottom surface of the low-pressure chamber 31 are made of stainless steel, but the ceiling portion is a quartz window 34, so that infrared light hν from an infrared lamp 37 arranged outside the chamber can be taken in. . An oxidizing chemical supply pipe 35 for supplying an oxidizing chemical from the direction of arrow C is inserted into the low-pressure chamber 31, and the chemical is discharged onto the wafer W from a dispenser nozzle 36 attached to the tip thereof. As a result, a liquid film Lf is formed. Further, the stage 13 is rotatable about its support in the direction of arrow D, so that the oxidizing chemical can be quickly applied to the entire surface of the wafer W by centrifugal force. The rotational speed of the stage 13 is variable, and is designed to rotate at a higher speed when the liquid film Lf is shaken off after the heat treatment.

In any of the above methods (a) and (b), in the present invention, the heating temperature during the heat treatment is set to about 30.
The temperature is preferably set to 0 ° C. or higher. In a lower temperature range, a sufficient oxygen diffusion rate may not be obtained depending on a combination with the gas pressure. On the other hand, regarding the upper limit of the heating temperature, particularly when the high dielectric constant film is a capacitor insulating film laminated on the metal lower electrode, it is important that the temperature range be lower than the heat resistant temperature of the metal lower electrode. is there. This temperature depends on the type of metal constituting the lower electrode, but is preferably about 600 ° C. or less. Note that the metal lower electrode described here includes a barrier metal. Within the above temperature range, the metal constituting the capacitor electrode diffuses into the capacitor insulating film with the deterioration of the barrier metal to form a new impurity level, or has already been formed in the underlying substrate. There is almost no concern that the impurity profile of the impurity diffusion layer changes due to re-diffusion. A typical constituent material of the metal lower electrode is I
n, Pt, Ir, Ru, W, and the like.

When the metal lower electrode is formed of a metal material that forms an insulating oxide, when oxygen penetrating through the high dielectric constant film reaches the interface with the metal lower electrode, the metal lower electrode is formed there. An insulating film is formed, which results in increasing the substantial thickness of the capacitor insulating film and reducing the capacitance of the capacitor. Therefore, in the present invention, it is particularly preferable that the metal lower electrode is made of a metal material that gives a conductive oxide, in any of the above methods (a) and (b). Representative examples of such metallic materials include I
n, Ru, and Ir.

Hereinafter, specific embodiments of the present invention will be described. Example 1 In this example , the Ta ₂ O ₅ film was modified using the heat treatment apparatus shown in FIG. 2 and a gas containing O ₃ . First, the structure of the used sample wafer will be described with reference to FIG. This figure shows a state in the course of manufacturing a DRAM having a planar capacitor using a Ta ₂ O ₅ film as a capacitor insulating film. To briefly explain the steps so far, first, a field oxide film 42 is formed on a silicon 41 substrate by, for example, the LOCOS method, and then a gate oxide film is formed in an element formation region defined by the field oxide film 42, and a word line 43 is formed. Patterning,
LDD ion implantation, LDD sidewall formation, and source / drain ion implantation are sequentially performed. Subsequently, the entire surface of the wafer W is covered with an interlayer insulating film 45, a contact hole opening for bit line contact, formation of a bit line 46, formation of an interlayer insulating film 45 again, contact hole opening for storage node contact, pad Filling contact holes with electrodes 47, depositing the entire surface of storage node electrode 48, batch patterning of pad electrode 47 and storage node electrode 48,
Then, the entire surface of the Ta ₂ O ₅ film 49 as the capacitor insulating film is sequentially formed, and the state shown in the figure is obtained. However, in this state, the capacitor 51 has not been completed yet, and after the modification process of the Ta ₂ O ₅ film 49 is finished, the plate electrode 50 is formed thereon before the capacitor 51 is formed.

The pad electrode 47 is, for example, an impurity-containing polysilicon film, and the storage node electrode 48 is about 2 mm thick.
It is formed of Ru of 00 nm. In addition, the above Ta ₂ O
₅ Film 49 is made of pentaethoxy tantalum Ta (OC ₂ H ₅ )
_The film is formed to a thickness of about 10 nm by MOCVD using _5, and contains some C atoms and H atoms derived from the source gas as impurities in the film. Here, a Ta ₂ O ₅ film 49 having a relative dielectric constant ε of 16 immediately after film formation was used.

The wafer W was placed on the stage 13 of the heat treatment apparatus shown in FIG. 2, and the inside of the high-pressure chamber 11 was evacuated using a vacuum evacuation system (not shown). The internal volume of the high-pressure chamber 11 is about 1.0 liter. At the same time, the wafer W was heated to 450 ° C. using the heater 14. Next, O ₃ and He are mixed in the high-pressure chamber 11 at 1:
A mixed gas mixed at a molar ratio of 3 was introduced from the gas introduction pipe 15 and pressurized, and was further maintained for 10 minutes when the inside of the chamber reached 100 atm.

In this process, the oxygen-based active species generated from O ₃ rapidly diffused into the Ta ₂ O ₅ film 49 under high pressure conditions to fill the voids due to oxygen vacancies and oxidize impurities in the film. . As a result, in the present invention, the relative dielectric constant ε of the Ta ₂ O ₅ film 49 increases to 22 even though the heat treatment is performed for a short time in a temperature range slightly higher than the conventional plasma processing, Also, the leak current was reduced by about 5 orders (electrolytic strength = 1 MV / cm). Also, a Ta ₂ O ₅ film 4
Since Ru is used for the storage node electrode 48, which is the base of No. 9, oxygen-based active species diffuse to the interface between the Ta ₂ O ₅ film 49 and the storage node electrode 48, and the surface of the storage node electrode 48 is oxidized. Even so, the generated oxide RuO ₂ has conductivity. Therefore, there were no problems such as an increase in the apparent thickness of the capacitor insulating film and a decrease in the capacitance of the capacitor due to the increase in the apparent thickness.

Example 2 In this example, the Ta ₂ O ₅ film constituting the capacitor insulating film of the DRAM was also modified by using the heat treatment apparatus shown in FIG. 1 and the gas containing O ₃ . . The used sample wafer is the same as that used in Example 1. The wafer W was placed on the stage 3 of the heat treatment apparatus in FIG. 1, and the inside of the high-pressure chamber 1 was evacuated using a vacuum evacuation system (not shown). The internal volume of the high-pressure chamber 1 is about 1.0 liter. At the same time, the heater 4
Was used to heat the wafer W to 450 ° C. Next, a mixed gas obtained by mixing O ₃ and He in a molar ratio of 1: 3 is introduced into the high-pressure chamber 1 through the gas introduction pipe 5 and pressurized. Was turned ON, and this state was maintained for 10 minutes. Here, a low-pressure mercury lamp was used as the ultraviolet lamp 7.

[0030] O ₃ has a light absorption band called Hartley (Hartley) band in the ultraviolet region, when irradiated with ultraviolet light having a wavelength of at most 310 nm, the following reaction scheme _{O 3 + hν → O 2 (} 1 Δ) + O ^{* (1} D) by generating singlet oxygen radicals O ^* a ⁽¹ D). O ₃
Is decomposed by visible light, but the decomposition product at this time is 3
It is singlet oxygen and has lower energy than singlet oxygen.
The singlet oxygen radical O ^* ( ¹ D) thus generated
There effectively act results in the Ta ₂ O ₅ film 49, also increases the dielectric constant ε 23 of the Ta ₂ O ₅ film 49 in this embodiment, also the leakage current is also about 5 orders of magnitude (electric field intensity = 1 MV / cm A) reduced.

Example 3 In this example, the heat treatment apparatus shown in FIG. 3 and H ₂ O ₂ as an oxidizing chemical were used to modify a Ta ₂ O ₅ film also constituting a capacitor insulating film of a DRAM. Was done. The used sample wafer is the same as that used in Example 1. The wafer W was placed on the stage 23 of the heat treatment apparatus in FIG. 3, and the inside of the low-pressure chamber 21 was evacuated using a vacuum evacuation system (not shown). At the same time, the wafer W was heated to 450 ° C. using the heater 24, and the shower head was also heated to about 100 ° C. using the heater 26.

In this state, H generated in the vaporizer I
The mist M of ₂ O ₂ was sent into the low pressure chamber 21.
The mist M converts the carrier gas N ₂ to 1000 SC
It was produced by blowing into the closed container 27 at the flow rate of CM. At this time, H ₂ O ₂ was supplied into the low-pressure chamber 21 at a rate of 5.0 g / min (H ₂ O ₂ concentration was 65%). The pressure in the chamber when the mist M was supplied was 10 Torr, and the heat treatment time was 15 minutes. In the above process, the H ₂ O ₂ particles in contact with the heated wafer W immediately undergo thermal decomposition, and the generated oxygen-based active species becomes Ta.
_This contributed to the modification of the ₂ O ₅ film. Also in this example, the relative dielectric constant ε of the Ta ₂ O ₅ film 49 was increased to 21, and the leak current was reduced by about 5 digits (electrolytic strength = 1 MV / cm).

Embodiment 4 In this embodiment , the heat treatment apparatus shown in FIG. 4 and H ₂ O ₂ as an oxidizing chemical were used, and the Ta ₂ O ₅ film 49 also constituting a capacitor insulating film of a DRAM was modified. The quality went. The used sample wafer is the same as that used in Example 1. The wafer W was placed on the stage 33 of the heat treatment apparatus in FIG. 4, and the inside of the low-pressure chamber 21 was evacuated using a vacuum evacuation system (not shown). The evacuation at this time is performed at such an evacuation speed that the liquid film Lf of the oxidizing chemical liquid L formed on the wafer W is not rapidly evaporated and that the liquid film Lf shaken off after the heat treatment can be sucked. It should be good.

In this state, the H ₂ O ₂ aqueous solution was gently discharged from the dispenser nozzle 36, and the stage 33 was rotated to spread the H ₂ O ₂ solution over the entire surface of the wafer W. continue,
The infrared lamp 37 was turned on to irradiate infrared light hν.
Since the infrared light matches the basic absorption band of the silicon substrate 41, the temperature of the wafer W can be raised quickly, and thereby, Ta ₂ O ₅ due to decomposition products of H ₂ O ₂ can be obtained.
The modification of the film 49 could be promoted. Note that the oxidizing chemical liquid L may be appropriately replenished during infrared irradiation. Also according to the present embodiment, the relative dielectric constant ε of the Ta ₂ O ₅ film 49 increases to 21 and the leak current also increases by about 5 digits (electrolytic strength = 1 MV / c).
m) reduced.

As mentioned above, four specific embodiments of the present invention have been described, but the present invention is not limited to these embodiments. For example, in each of the above embodiments, a Ta ₂ O ₅ film as a high dielectric constant film, O ₃ as a gas capable of generating oxygen-based active species, H ₂ O ₂ as an oxidizing chemical, and Ru as a constituent metal of the storage node electrode. Although the case of selection is described, the material is not limited to these, and the materials exemplified in this specification can be used in appropriate combination. In addition, the details of the configuration of the heat treatment apparatus, the configuration of the sample wafer, the film thickness of each part, the heat treatment conditions, and the like, and combinations thereof, can be appropriately changed and selected.

[0036]

As is apparent from the above description, according to the present invention, it is possible to improve the film quality of a high dielectric constant film at a lower temperature than in the conventional case.
It can be performed with low damage and in a short time. Therefore, when this high dielectric constant film is applied to a capacitor insulating film of a DRAM, it is possible to provide a DRAM which is suitable for high integration and has high speed and high reliability. In addition, among the high dielectric constant films described above, perovskite-based composite oxides other than Ta ₂ O ₅ are also ferroelectrics and have both piezoelectricity and focus. Therefore, by modifying the high dielectric constant film according to the present invention, the performance of devices such as a piezoelectric element, an electro-optical element, an infrared detecting element, and a ceramic capacitor is remarkably improved. Very large.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one configuration example of a heat treatment apparatus of the present invention provided with ultraviolet irradiation means including an optical fiber and a high-pressure chamber.

FIG. 2 is a schematic cross-sectional view showing one configuration example of a heat treatment apparatus used for heat treatment under a high-pressure atmosphere in the present invention.

FIG. 3 is a schematic cross-sectional view showing one configuration example of a heat treatment apparatus used for heat treatment in a low-pressure mist atmosphere in the present invention.

FIG. 4 is a schematic cross-sectional view showing one configuration example of a heat treatment apparatus used for heat treatment by infrared irradiation in the present invention.

FIG. 5 is a schematic cross-sectional view showing a configuration example of a DRAM using a high dielectric constant film modified by the present invention as a capacitor insulating film of a planar capacitor.

[Explanation of symbols]

1,11 high-pressure chamber 3,13,23,33 stage 4,14,24,26 heater 5,15 gas introduction tube 6 optical fiber 7,37 ultraviolet lamp
8, 38: Reflecting mirror 21, 31: Low pressure chamber 27:
Sealed container 34 ... Quartz window 35 ... Oxidizing chemical supply pipe 3
6 ... dispenser nozzles 48 ... storage node electrode (lower electrode) 49 ... T ₂ O ₅ film (capacitor insulating film) 5
0: plate electrode (upper electrode) 51: capacitor W
... Wafer I ... Vaporizer M ... Mist L ... Chemical liquid Lf ... Oxidizing liquid film

Claims (13)

[Claims] 1. A high-dielectric-constant film made of a metal oxide is heat-treated in an atmosphere containing a gas capable of generating oxygen-based active species at a partial pressure of at least 1 atm or a total pressure. A method for modifying a high dielectric constant film. 2. The method for modifying a high dielectric constant film according to claim 1, wherein the heat treatment is performed while irradiating the high dielectric constant film with ultraviolet rays. 3. The method according to claim 1, wherein the high dielectric constant film is a capacitor insulating film laminated on a metal lower electrode, and the heat treatment is performed in a temperature range equal to or lower than a heat resistant temperature of the metal lower electrode. The method for modifying a high dielectric constant film as described above. 4. The method for modifying a high dielectric constant film according to claim 3, wherein the metal lower electrode is formed using a metal material capable of generating a conductive oxide. 5. The method according to claim 1, wherein O ₃ is used as said gas. 6. A method for modifying a high dielectric constant film, wherein a heat treatment is performed while a liquid capable of generating oxygen-based active species by thermal decomposition is brought into contact with the high dielectric constant film made of a metal oxide. 7. The method for modifying a high dielectric constant film according to claim 6, wherein the liquid is brought into contact with the heated high dielectric constant film in an aerosol state. 8. The method for modifying a high dielectric constant film according to claim 6, wherein the liquid is held on the high dielectric constant film by the surface tension thereof before the start of the heat treatment. 9. The method according to claim 6, wherein the high dielectric constant film is a capacitor insulating film laminated on a metal lower electrode, and the heat treatment is performed in a temperature range equal to or lower than a heat resistant temperature of the metal lower electrode. The method for modifying a high dielectric constant film as described above. 10. The method for modifying a high dielectric constant film according to claim 6, wherein the metal lower electrode is formed using a metal material capable of generating a conductive oxide. 11. The method according to claim 6, wherein a hydrogen peroxide solution is used as the liquid. 12. A pressure vessel for accommodating the object to be processed, an atmosphere adjusting means for generating a pressurized atmosphere in the pressure vessel, a stage for holding the object in the pressure vessel, A heat treatment apparatus comprising: a heating unit that heats a body; and an ultraviolet irradiation unit that irradiates the object to be processed with ultraviolet light. 13. The heat treatment apparatus according to claim 12, wherein said ultraviolet irradiation means includes an optical fiber disposed so that an ultraviolet light emitting end face faces a workpiece.