JP2001158964A - Semiconductor system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film deposition method by which an iridium thin film or an iridium oxide thin film excellent in the coverability of the surface of difference in level and small in the variation of film thickness is deposited, to provide a semiconductor system using the same iridium thin film or iridium oxide thin film, and also to provide a method for producing the same. SOLUTION: By a chemical vapor phase growth method using Ir(DPM)3 as the raw material, an iridium thin film or an iridium oxide thin film is deposited. Even on a base substrate having surface ruggedness, the iridium thin film or iridium oxide thin film excellent in coverability can be deposited. Moreover, the variation of the film thickness can be suppressed to a small degree.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a thin film, and more particularly to a method of forming a thin film for forming an iridium thin film or an iridium oxide thin film, a semiconductor device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An iridium thin film is made of SrTiO ₃ , (B
a, Sr) is used as an electrode of a high dielectric material ₃ such as TiO. Conventionally, in the manufacturing process of semiconductor devices,
A sputtering method has been mainly used for forming an iridium thin film.

FIG. 11 shows an example of a sputtering apparatus. In a film forming chamber 84 for forming an iridium thin film, a target 86 made of iridium bulk and a substrate 88 for depositing the iridium thin film are arranged to face each other.
A DC power supply 90 is connected between the target 86 and the substrate 88 so that a large negative voltage can be applied to the target 86 serving as a cathode. An Ar (argon) gas supply pipe 92 is further connected to the film forming chamber 84 so that Ar, which is a sputtering gas, can be introduced into the film forming chamber 84. Further, the substrate holding section 94 is provided with a heater 96 for heating the substrate 88 as required during film formation.

Next, a method for forming an iridium thin film by a sputtering method will be described. First, the inside of the film forming chamber 84 is exhausted 9
After the pressure is reduced by a vacuum pump (not shown) connected to 8, Ar gas is introduced into the film formation chamber 84 from an Ar gas supply pipe 92, and the pressure in the film formation chamber 84 is adjusted. For example, Ar
By setting the gas flow rate to 10 to 100 sccm, the pressure is adjusted to about 1 to 5 × 10 ⁻³ Torr.

Next, a DC voltage is applied between the substrate 88 and the target 86 to generate Ar plasma. As a result, the dissociated Ar ions collide with the target 86 serving as the cathode to sputter iridium atoms. When the sputtered iridium atoms reach the substrate 88, an iridium thin film is deposited on the substrate 88. Thus, the iridium thin film was formed by the sputtering method.

Recently, Japanese Patent Application Laid-Open No. 6-290789 has disclosed
Japanese Patent Laid-Open Publication No. HEI 7-264, proposes a method of forming an iridium thin film by a CVD (Chemical Vapor Deposition) method using an organic compound of iridium.

[0007]

However, in the thin film forming method for forming an iridium thin film using the above-mentioned conventional sputtering method, when an iridium thin film is deposited on a substrate on which a concavo-convex pattern is drawn, the upper surface and the side surface of the step are formed. However, there is a problem that a film cannot be deposited with the same thickness.

For this reason, it is difficult to deposit an iridium thin film on a complicated pattern.
(Dynamic Random Access Memory) There is a problem that it cannot be used as an electrode of a high dielectric material in a grooved capacitor cell and a stacked capacitor cell structure. Further, when an iridium thin film is deposited by the method described in JP-A-6-290789, the coatability on a substrate having a concavo-convex pattern is much better than when deposited by a sputtering method. When, for example, iridium acetylacetonate (hereinafter referred to as Ir (acac) ₃ ) is used as a source of iridium, it is difficult to stably supply the source gas, and the thickness of the formed iridium thin film varies. There was a problem that it became large. In addition, there has not been found any raw material capable of reducing the variation in the thickness of the iridium thin film when formed by the CVD method.

An object of the present invention is to provide a thin film forming method for depositing an iridium thin film and an iridium oxide thin film having small film thickness variations by a CVD method having excellent step surface coverage, a semiconductor device using the iridium thin film and the iridium oxide thin film. It is to provide a manufacturing method thereof.

[0010]

An object of the present invention is to provide an Ir (DP)
M) A thin film forming method characterized by forming an iridium thin film or an iridium oxide thin film by a chemical vapor deposition method using ₃ as a raw material. In the above-mentioned thin film forming method, it is preferable that the substrate on which the iridium thin film or the iridium oxide thin film is formed is heated to a temperature of 500 to 600 ° C.

In the above-described thin film forming method, it is preferable that a reaction pressure in a film forming chamber for forming the iridium thin film or the iridium oxide thin film is set to 1 to 20 Torr. In the above-described thin film forming method, when forming the iridium thin film, it is desirable to introduce hydrogen gas into a film formation chamber where the iridium thin film is formed.

In the above-mentioned thin film forming method, it is preferable that the partial pressure of the hydrogen gas is 0.1 to 14 Torr. In the thin film forming method, when forming the iridium oxide thin film, an oxygen gas is supplied to the film forming chamber where the iridium oxide thin film is formed in an amount of 0.5 to 16 To.
It is desirable to introduce at a partial pressure of rr.

The present invention is also achieved by a semiconductor device having an iridium thin film or an iridium oxide thin film formed by the above-described thin film forming method. Also,
In a semiconductor device having a capacitor in which an upper electrode, a dielectric film, and a lower electrode are sequentially laminated, the upper electrode or the lower electrode has an iridium thin film formed by the above-described thin film forming method. This is also achieved by a semiconductor device characterized by the above.

Further, in the above-mentioned semiconductor device, it is preferable that the upper electrode or the lower electrode is a laminated film of the iridium thin film and the iridium oxide thin film. Further, in the above-described semiconductor device, it is preferable that the upper electrode or the lower electrode is a laminated film of the iridium thin film and the platinum thin film. In the above-described semiconductor device, it is preferable that the upper electrode or the lower electrode is a laminated film of the iridium thin film, the iridium oxide thin film, and a platinum thin film.

In the above-described semiconductor device, the iridium oxide thin film is preferably an iridium oxide thin film formed by the above-described thin film forming method. Also,
The present invention is also achieved by a method for manufacturing a semiconductor device, comprising a step of forming an iridium thin film or an iridium oxide thin film by the above-described thin film forming method.

[0016]

According to the present invention, an iridium thin film and an iridium oxide are formed by a CVD method using Ir (DPM) ₃ as a raw material. And an iridium oxide thin film can be formed. Further, as compared with a conventional film forming method using Ir (acac) ₃ as a raw material, variation in film thickness can be suppressed to be small.

Further, the substrate temperature for forming a film is set to 500 to 600.
If the temperature is set to ° C., a high-quality iridium thin film or iridium oxide thin film can be formed. When the reaction pressure in the film formation chamber is set to 1 to 20 Torr, a high-quality iridium thin film and iridium oxide thin film can be formed. In addition, when hydrogen gas is introduced into the film formation chamber during the formation of an iridium thin film, an iridium thin film in which carbon is little mixed into the film can be formed, so that the resistivity of the iridium thin film can be significantly reduced. . Further, the flatness of the surface can be improved.

The partial pressure of the hydrogen gas is set to 0.1 to 14 To
If rr is set, the above effect can be obtained. In addition, when the partial pressure of the oxygen gas introduced into the film formation chamber when forming the iridium oxide thin film is set to 0.5 to 16 Torr, a good quality iridium oxide thin film can be formed.

Further, since a high-quality iridium thin film or iridium oxide thin film having a small thickness variation and a good quality is formed by the above-described thin film forming method, the reliability of the semiconductor device can be improved. Further, the iridium thin film can be applied to a semiconductor device having a capacitor in which an upper electrode, a dielectric film, and a lower electrode are sequentially stacked.

In the above semiconductor device, a laminated film of an iridium thin film and an iridium oxide thin film can be applied to the upper electrode or the lower electrode. In the above semiconductor device, a stacked film of an iridium thin film and a platinum thin film can be applied to the upper electrode or the lower electrode. In the above semiconductor device, a stacked film of an iridium thin film, an iridium oxide thin film, and a platinum thin film can be applied to the upper electrode or the lower electrode.

In the above semiconductor device, if the iridium oxide thin film is formed by the above thin film forming method,
Since a high-quality iridium oxide thin film can be formed, reliability and the like of a semiconductor device can be improved. In addition, when an iridium thin film or an iridium oxide thin film is formed by the above thin film forming method, a high-quality semiconductor device can be manufactured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a thin film according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of a CVD apparatus used in the thin film forming method according to the present embodiment.
Is an X-ray diffraction spectrum of the iridium thin film and the iridium oxide thin film formed by the thin film forming method according to the present embodiment, FIG. 3 is a graph showing a change in the film thickness of the iridium thin film with respect to the film formation time, and FIG. FIG. 5 is a graph showing the relationship between the resistivity and FIG. 5 is a graph showing the relationship between the hydrogen partial pressure and the surface irregularities of the iridium thin film.

The CV used in the thin film forming method according to this embodiment
The D device will be described with reference to FIG. A vacuum pump 12 is connected to the film forming chamber 10 for growing a thin film, so that the pressure inside the film forming chamber 10 can be reduced. A susceptor 16 for mounting a substrate 14 on which a film is to be formed is provided inside the film forming chamber 10. The susceptor 16 is provided with a heater (not shown) for heating the substrate 14 during film formation.

The film forming chamber 10 further contains H ₂ (hydrogen) or O ₂
A gas supply pipe 18 for introducing (oxygen) gas and a gas supply pipe 20 for introducing a gas containing an organic metal material are connected. Further, a shower head 22 is formed in the film forming chamber 10 so that the gas introduced into the film forming chamber 10 in this way is uniformly supplied into the film forming chamber 10. The other end of the gas supply pipe 20 is connected to a gas control device 24 that heats and sublimates the metal compound and introduces the metal compound into the film formation chamber 10 together with the carrier gas.

The gas control device 24 has a general formula

[0026]

Embedded imageIridium dipivaloyl meta, a metal raw material represented by
(Hereinafter Ir (DPM) _ThreeRaw material volume)
A vessel 26 is provided. Ir (DPM)_ThreeIs at room temperature
Is an orange powder.
Sublimate and use. For this reason, the raw material container 26 is
26 to a temperature of about 150 to 200 ° C.
It is placed inside the warm bath 28.

A gas supply pipe 30 for introducing Ar gas, which is a carrier gas, is further connected to the raw material container 26. By introducing Ar gas from the gas supply pipe 30 into the raw material container 26, sublimation is performed together with Ar gas. Ir
(DPM) ₃ can be introduced into the film forming chamber 10. A heater 32 is provided in the film forming chamber 10, the gas supply pipes 18 and 20, and the pipe between the film forming chamber 10 and the raw material container 26 in order to suppress gas condensation in the pipe. Is kept at 150 to 210 ° C. which is higher than the sublimation temperature of Ir (DPM) ₃ by, for example, about 5 ° C.

Next, the method of forming a thin film according to the present embodiment is shown in FIG.
This will be described with reference to FIG. After the pressure in the film forming chamber 10 is reduced by the vacuum pump 12, the substrate 14 on which the iridium thin film is deposited is heated by the heater of the susceptor 16. Next, an Ar gas as a carrier gas is flowed at a predetermined flow rate and introduced into the film formation chamber together with the sublimated Ir (DPM) ₃ . At the same time, by introducing H ₂ gas from the gas supply pipe 18, Ir (DPM) ₃ and H ₂ gas react on the substrate 14, and an iridium thin film is deposited on the substrate 14.

When depositing an iridium oxide thin film on the substrate 14, O ₂ gas is introduced into the film forming chamber 10 instead of H ₂ gas, and Ir (DPM) ₃ and O ₂ gas are deposited on the substrate 14. The reaction may be carried out. FIG. 2 shows that the pressure in the film forming chamber 10 is 10 T
This is a result of measuring an iridium thin film and an iridium oxide thin film formed by setting the carrier gas flow rate to 300 sccm and the partial pressure of H ₂ gas or O ₂ gas to 0.5 Torr by X-ray diffraction. In the figure, (a) shows the diffraction spectrum from the silicon substrate on which the iridium oxide thin film was grown,
(B) shows a diffraction spectrum from the silicon substrate on which the iridium thin film was grown.

The iridium thin film grows on a (100) silicon substrate, and the iridium oxide thin film grows on a (100) silicon substrate.
It grew on a 20 nm iridium thin film deposited on a silicon substrate. The deposition rates were both 100 nm / min. As shown, in each case, a typical diffraction peak was observed, which indicates that an iridium thin film and an iridium oxide thin film were grown.

The inventor of the present application has proposed that the iridium thin film grown in this way can be used in the conventional Ir (acac)
_{According to 3,} we have newly found that the stability of the manufacturing process is superior to the case of growing an iridium thin film. This will be described in detail below. FIG. 3 shows a change in film thickness when film formation with the same film thickness is repeatedly performed. The film forming conditions are as shown in Table 1.

[0032]

[Table 1] As shown, when Ir (DPM) ₃ is used as the metal raw material, the thickness of the deposited iridium thin film hardly changes. On the other hand, when Ir (acac) ₃ is used, the variation in film thickness is very large.
When the operation is performed for 0 hours or more, the film thickness decreases.

The reason why the film thickness variation is large when using Ir (acac) ₃ is that Ir (acac) ₃ cannot obtain stable sublimation characteristics. That is, if the sublimation characteristics are not stable, the supply amount of the source gas introduced into the film forming chamber 10 changes, and the film formation speed depending on the supply amount of the source gas changes, so that the film thickness varies. When Ir (acac) ₃ is used, the film thickness is reduced by operating for 20 hours or more.
c) This is due to deterioration of ₃ . Over time Ir (DPM) and an organometallic raw material ₃ Ir (acac) ₃
Degrades, but the rate of degradation is mainly due to temperature.
Therefore, Ir (acac) ₃ having a high sublimation temperature has an Ir
(DPM) Deterioration is faster than that of ₃ , resulting in a decrease in film thickness.

From these facts, the raw material for forming the iridium thin film by the CVD method is Ir (ac
It is considered that Ir (DPM) ₃ is more suitable than ac) ₃ . Next, the effect of H ₂ gas introduced when forming an iridium thin film will be described.

FIG. 4 is a graph showing a change in resistivity with respect to a hydrogen partial pressure, and FIG. 5 is a graph showing a change in surface unevenness with respect to a hydrogen partial pressure. As shown in the figure, when H ₂ gas is not introduced at the time of film formation, the resistivity of the iridium thin film is 179.
2 [Ω · cm]. However, when H ₂ gas is introduced during film formation, the value sharply decreases. For example, when the hydrogen partial pressure is about 0.3 [Torr], the value is 148 [Ω · c].
m]. When the hydrogen partial pressure is further reduced, the resistivity becomes 42.8 [Ω · when the hydrogen partial pressure is about 0.625 [Torr].
cm] and a hydrogen partial pressure of about 0.7 [Torr], the resistivity becomes 33.8 [Ω · cm], and the specific resistance can be reduced with an increase in the hydrogen partial pressure. The reason that the resistivity depends on the hydrogen partial pressure is due to the effect of the carbon concentration contained in the film.

As a material for forming an iridium thin film, Ir
When (DPM) ₃ is used, since the raw material contains a large amount of carbon, the formed iridium thin film also contains carbon. Although such introduction of carbon causes an increase in resistivity, if the added H ₂ gas reacts with carbon in the film, hydrogen and oxygen react with each other in the gas phase or in the substrate surface to generate hydrocarbons. Therefore, the concentration of carbon introduced into the film can be reduced.

As shown in FIG. 5, the introduction of H ₂ gas at the time of film formation has an effect of reducing the surface irregularities of the formed iridium thin film. As described above, according to this embodiment, since the iridium thin film and the iridium oxide thin film are grown by the CVD method using Ir (DPM) ₃ , the film is formed with good coverage even on the substrate on which the uneven pattern is drawn. can do.

Further, since the iridium thin film is grown by introducing hydrogen into the reaction chamber, it is possible to form an iridium thin film having a low resistivity and containing less carbon in the film. According to the inventor of the present application, in order to form a high-quality iridium thin film, the substrate is heated to a temperature of about 500 to 600 ° C. during film formation, and the pressure in the film forming chamber during film formation is 1 to 500 ° C. 20To
It is preferable to set the pressure to about rr and the hydrogen partial pressure to about 0.1 to 14 Torr.

In order to form a high-quality iridium oxide thin film, the temperature of the substrate is raised to about 500 to 600 ° C. during the film formation, and the pressure in the film forming chamber during the film formation is 1 to 20 Torr.
r, and the oxygen partial pressure is desirably set to about 0.5 to 16 Torr. Next, a semiconductor device and a method of manufacturing the same according to a second embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a view showing a structure of the semiconductor device according to the present embodiment, FIG. 7 is a sectional view showing a method of manufacturing the semiconductor device according to the present embodiment, and FIGS. It is a figure showing the structure of an apparatus. In this embodiment,
As an example of applying the iridium thin film formed by the thin film manufacturing method according to the first embodiment to a semiconductor device, a structure and a manufacturing method of a thin film capacitor using the iridium thin film as a lower electrode will be described.

First, the structure of the semiconductor device according to the present embodiment will be explained with reference to FIG. On an insulating film 42 formed on a silicon substrate 40, a lower electrode 48 formed by sequentially laminating an iridium thin film 44 and an iridium oxide thin film 46
Are formed. On the lower electrode 48, SrTiO ₃
The capacitor dielectric film 50 is formed. On the capacitor dielectric film 50, an upper electrode 52 made of TiN is formed. An insulating film 54 is formed on the capacitor thus formed, and a through-hole 56 formed in the insulating layer 54 has a wiring layer 58 connected to the upper electrode 52 and the lower electrode 48.
Are formed.

Next, the method for fabricating the semiconductor device according to the present embodiment will be explained with reference to FIG. First, an iridium thin film 44 serving as a lower electrode 48 is formed on a silicon substrate 40 on which an insulating film 42 is formed by CV using Ir (DPM) ₃ as a raw material.
It is deposited by the D method. The conditions for forming the iridium thin film 44 include, for example, a sublimation temperature of 150 ° C., a flow rate of Ar gas as a carrier gas of 300 sccm, and a flow rate of H ₂ gas of 1
00 to 300 sccm, substrate temperature 500 to 600 ° C., film forming pressure 1 to 10 Torr, film forming speed 10 nm / min,
The thickness is set to 100 nm.

Next, the surface of the iridium thin film 44 thus formed is subjected to, for example, RTA (short annealing:
Oxidized using Rapid Thermal Annealing)
An iridium oxide thin film 46 having a thickness of about 0 to 50 nm is formed. The RTA conditions are, for example, a processing temperature of 600 ° C. and a processing time of 10 to 20 seconds. Subsequently, the iridium thin film 44 is formed by ordinary lithography and ion milling techniques.
The lower electrode 48 is formed by patterning a laminated film composed of the thin film and the iridium oxide thin film 46.

Thereafter, an SrTiO ₃ film serving as the capacitor dielectric film 50 is deposited by a sputtering method. The sputtering conditions include, for example, SrTiO ₃ as a target, Ar gas containing 10% O ₂ as a sputtering gas, a growth degree of vacuum of 10 mTorr, a substrate temperature of 450 ° C., and a film thickness of 100 nm.
And Next, a TiN film to be the upper electrode 52 is deposited by a sputtering method. The sputtering conditions include, for example, A containing Ti as a target and 20% N ₂ as a sputtering gas.
r gas, growth vacuum degree 10 mTorr, substrate temperature 2
The temperature is set to 00 ° C. and the thickness is set to 100 nm.

Subsequently, the TiN film is processed by reactive ion etching to pattern the upper electrode 52 (FIG. 7A). The etching conditions include, for example, Cl ₂ as an etching gas, a pressure of 200 mTorr, a substrate temperature of 60 ° C., and an input power of 200 W. Then, after patterning the resist 60 by a normal lithography technique, the SrTiO ₃ film is patterned by wet etching to form a capacitor dielectric film 50 (FIG. 7B).

Next, an insulating film 54 is deposited on the capacitor thus formed by the CVD method. The film forming conditions are, for example, using a mixed gas of SiH ₄ , N ₂ O, and N ₂ as a reaction gas, a pressure of 1 Torr, and a film forming speed of 130 nm / m.
in, substrate temperature 320 ° C., input power 20 W, film thickness 250
nm. Subsequently, a through hole 56 for leading a wiring from the lower electrode 48 and the upper electrode 52 is opened in the insulating film 54 (FIG. 7C). Reactive ion etching is used to form through holes. The etching conditions are, for example, a mixed gas of CF ₄ and CHF ₃ as a reaction gas, a pressure of 200 mTorr, and an etching rate of 70 nm.
/ Min, the substrate temperature is 40 ° C., and the input power is 200 W.

After that, Al to be the wiring layer 58 is formed by sputtering and patterned to form the wiring layer 5.
8 (FIG. 7D). The sputtering conditions include, for example, Ar gas as a sputtering gas, a pressure of 1 mTorr, a film forming speed of 600 nm / min, a substrate temperature of room temperature, a power of 7 kW, and a film thickness of 600 nm. The etching condition is, for example, that Cl ₂ is used as an etching gas and the pressure is 200 mT.
orr, an etching rate of 500 nm / min, a substrate temperature of 40 ° C., and an input power of 200 W.

As a result of evaluating the leak characteristics of the thin film capacitor thus formed, an area of 100 × 100 μm was obtained.
The leakage current when a 10 V bias is applied between the upper electrode 52 and the lower electrode 48 of the m ² capacitor is 1 × 1
It was 0 ^-6 cm ^-2 . The relative dielectric constant of the capacitor dielectric film 50 was 200, and a capacitor having a high relative dielectric constant and excellent leak characteristics could be formed.

As described above, according to the present embodiment, Ir (D
PM)_ThreeFormed by CVD method using aluminum as raw material
Since the capacitor electrode is formed of a thin film of SrT
iO _ThreeUsing a high dielectric material such as
Sita can be formed. Note that, in the above embodiment,
Although the membrane capacitor was formed as a single unit, other devices
A capacitor may be applied.

For example, as shown in FIG. 8, the present invention can be applied to a DRAM capacitor. That is, the element isolation film 62
In the device region on the silicon substrate 40 defined by
A transfer transistor Tr including the source diffusion layer 64, the drain diffusion layer 66, and the gate electrode 68 is formed. On the drain diffusion layer 66, a wiring layer 70 forming a bit line is formed. On the silicon substrate 40 on which the transfer transistor Tr is formed, an interlayer insulating film 5 having a through hole 72 formed on a source diffusion layer 64 is formed.
4 are formed.

On the interlayer insulating film 74, a lower electrode 48 made of iridium and a S
Capacitor dielectric film 50 formed of rTiO ₃
And a capacitor C having an upper electrode 52 made of TiN. The lower electrode 48 is connected to the source diffusion layer 64 via a barrier layer 76 and a conductive plug 78 embedded in the through hole 72. An interlayer insulating film 80 is formed on the capacitor C, and a wiring layer 82 is formed thereon.

Thus, a DRAM composed of one transistor and one capacitor can be formed. In addition, since the iridium thin film is deposited by the CVD method, the iridium thin film has excellent coverage at the step. Therefore, the capacitor need not be the planar type capacitor shown in FIG. For example, as shown in FIG. 9, a capacitor having a simple stack structure can be formed.

In the above embodiment, a laminated film of the iridium thin film 44 and the iridium oxide thin film 46 is used as the lower electrode 48, and SrTi is used as the capacitor dielectric film 50.
Although an O ₃ film was used and a TiN film was used as the upper electrode 52, the present invention is not limited to these. For example, instead of SrTiO ₃ as the capacitor dielectric film 50,
(Ba, Sr) TiO ₃ may be used, or Pb (Z
(r, Ti) O ₃ or the like may be used.

The lower electrode 48 may be formed only of the iridium thin film 44 as shown in FIG. Also, an iridium oxide thin film 4 such as Pb (Zr, Ti) O ₃
When a material that reacts with P.6 is used as the capacitor dielectric film 50, the lower electrode 48 may be formed of a laminated film of the iridium thin film 44 and the Pt (platinum) film 47 as shown in FIG. Alternatively, as shown in FIG. 10C, the iridium thin film 44, the iridium oxide thin film 46, and Pt
It may be formed by a laminated film with the (platinum) film 47.

The upper electrode 52 may have the same structure as the lower electrode 48. Note that the upper electrode 52 is formed by a laminated film.
May be formed by reversing the stacking order of the respective layers with that of the lower electrode 48. In the above embodiment, the iridium oxide thin film 46 is formed by oxidizing the surface of the iridium thin film 44. However, as shown in the first embodiment, the iridium oxide thin film 46 is formed by a CVD method using Ir (DPM) _3. May be.

[0056]

As described above, according to the present invention, Ir (D
Since the iridium thin film and the iridium oxide are formed by the CVD method using PM) ₃ as a raw material, the iridium thin film and the iridium oxide thin film having excellent covering properties can be formed even on a base substrate having surface irregularities.

Further, compared with the conventional film forming method using Ir (acac) ₃ as a raw material, the variation in film thickness can be suppressed. Further, the substrate temperature for forming a film is set to 500 to
When the temperature is set to 600 ° C., a high-quality iridium thin film or iridium oxide thin film can be formed. Also,
When the reaction pressure in the film formation chamber is set to 1 to 20 Torr, a high-quality iridium thin film and iridium oxide thin film can be formed.

In addition, when hydrogen gas is introduced into the film formation chamber during the formation of the iridium thin film, the iridium thin film can be formed with less carbon in the film, and the resistivity of the iridium thin film is greatly reduced. be able to. Further, the flatness of the surface can be improved. If the partial pressure of the hydrogen gas is set to 0.1 to 14 Torr, the above effect can be obtained.

When the iridium oxide thin film is formed, the partial pressure of the oxygen gas introduced into the film forming chamber is set to 0.5 to 16 Torr.
By setting r, a high-quality iridium oxide thin film can be formed. In addition, since a high-quality iridium thin film or iridium oxide thin film with small thickness variation is formed by the above thin film forming method, reliability and the like of a semiconductor device can be improved.

The above iridium thin film can be applied to a semiconductor device having a capacitor formed by sequentially stacking an upper electrode, a dielectric film, and a lower electrode. In the above semiconductor device, a stacked film of an iridium thin film and an iridium oxide thin film can be used for the upper electrode or the lower electrode. In the above semiconductor device, a stacked film of an iridium thin film and a platinum thin film can be applied to the upper electrode or the lower electrode.

In the above semiconductor device, a laminated film of an iridium thin film, an iridium oxide thin film, and a platinum thin film can be applied to the upper electrode or the lower electrode. . Further, in the above-described semiconductor device, when the iridium oxide thin film is formed by the above-described thin film formation method, a high-quality iridium oxide thin film can be formed, so that the reliability and the like of the semiconductor device can be improved.

Further, if an iridium thin film or an iridium oxide thin film is formed by the above-described thin film forming method, a high quality semiconductor device can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view of a CVD apparatus used in a thin film forming method according to a first embodiment of the present invention.

FIG. 2 is an X-ray diffraction spectrum of the iridium thin film and the iridium oxide thin film formed by the thin film forming method according to the first embodiment of the present invention.

FIG. 3 is a graph showing a change in film thickness of an iridium thin film with respect to a film forming time.

FIG. 4 is a graph showing the relationship between the hydrogen partial pressure and the resistivity of an iridium thin film.

FIG. 5 is a graph showing a relationship between a hydrogen partial pressure and surface irregularities of an iridium thin film.

FIG. 6 is a diagram showing a structure of a semiconductor device according to a second embodiment of the present invention.

FIG. 7 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment of the present invention.

FIG. 8 is a diagram (part 1) illustrating a structure of a semiconductor device according to a modification of the second embodiment of the present invention;

FIG. 9 is a diagram (part 2) illustrating a structure of a semiconductor device according to a modification of the second embodiment of the present invention;

FIG. 10 is a diagram (part 3) illustrating a structure of a semiconductor device according to a modification of the second embodiment of the present invention;

FIG. 11 is a diagram illustrating a conventional thin film forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Film-forming chamber 12 ... Vacuum pump 14 ... Substrate 16 ... Susceptor 18 ... Gas supply piping 20 ... Gas supply piping 22 ... Shower head 24 ... Gas control device 26 ... Material container 28 ... Constant temperature bath 30 ... Gas supply piping 32 ... Heater Reference Signs List 40 silicon substrate 42 insulating film 44 iridium thin film 46 iridium oxide thin film 47 platinum film 48 lower electrode 50 capacitor dielectric film 52 upper electrode 54 insulating film 56 through hole 58 wiring layer 60 resist 62 element isolation film 64 source diffusion layer 66 drain diffusion layer 68 gate electrode 70 wiring layer 72 through hole 74 interlayer insulating film 76 barrier layer 78 plug 80 interlayer insulating film 82 wiring layer 84 Film forming chamber 86 ... Target 88 ... Substrate 90 ... DC power supply 92 ... Ar gas supply pipe 94 ... Substrate holder 96 ... heater 98 ... exhaust port

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[Procedure amendment]

[Submission date] October 6, 2000 (2000.10.
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

[Title of the Invention] Semiconductor device

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

An object of the present invention is to provide a semiconductor device having one conductivity type.
Formed on a semiconductor substrate with a gate insulating film interposed
The gate electrode of the MIS transistor connected to the
Before being formed in the semiconductor substrate on both sides of the gate electrode
Opposite source to be the source / drain of MIS transistor
An electric diffusion layer and a bit connected to one of the diffusion layers
Line and on the semiconductor substrate including the MIS transistor
An insulating film formed on the insulating film and the diffusion film formed on the insulating film
A contact hole reaching the other side of the layer, and the contact
A buried conductive layer buried in the hole;
Formed on the insulating film including only the conductive layer,
A barrier layer electrically connected to the conductive layer, and the barrier layer
An iridium thin film formed thereon, and the iridium thin film
The iridium oxide thin film formed thereon, and the iridium oxide
Electrode including a platinum film formed on a thin film of platinum
And a capacitor insulating film formed on the surface of the lower electrode
And an upper electrode formed on the surface of the capacitor insulating film.
Achieved by a semiconductor device characterized by having
You.

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The reason why the film thickness variation is large when using Ir (acac) ₃ is that Ir (acac) ₃ cannot obtain stable sublimation characteristics. That is, if the sublimation characteristics are not stable, the supply amount of the source gas introduced into the film forming chamber 10 fluctuates, and the film formation speed depending on the supply amount of the source gas changes, so that the film thickness varies. When Ir (acac) ₃ is used, the film thickness is reduced by operating for 20 hours or more.
c) This is due to deterioration of ₃ . As time passes, Ir (DPM) ₃ and Ir (acac) ₃ which are organometallic raw materials
Degrades, but the rate of degradation is mainly due to temperature.
Therefore, Ir (acac) ₃ having a high sublimation temperature has an Ir
(DPM) Deterioration is faster than that of ₃ , resulting in a decrease in film thickness.

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Claims (13)

[Claims] 1. A thin film forming method comprising forming an iridium thin film or an iridium oxide thin film by a chemical vapor deposition method using Ir (DPM) ₃ as a raw material. 2. The thin film forming method according to claim 1, wherein the substrate on which the iridium thin film or the iridium oxide thin film is formed is heated to a temperature of 500 to 600 ° C. 3. The thin film forming method according to claim 1, wherein a reaction pressure of a film forming chamber for forming the iridium thin film or the iridium oxide thin film is set to 1 to 20 Torr. . 4. The thin film forming method according to claim 1, wherein, when forming the iridium thin film, introducing a hydrogen gas into a film forming chamber for forming the iridium thin film. Characteristic thin film forming method. 5. The method for forming a thin film according to claim 4, wherein the partial pressure of the hydrogen gas is 0.1 to 14 Torr. 6. The thin film forming method according to claim 1, wherein when the iridium oxide thin film is formed, oxygen gas is supplied to a film forming chamber for forming the iridium oxide thin film. .5-
A method for forming a thin film, wherein the method is introduced at a partial pressure of 16 Torr. 7. A semiconductor device comprising an iridium thin film or an iridium oxide thin film formed by the thin film forming method according to claim 1. 8. A semiconductor device having a capacitor formed by sequentially stacking an upper electrode, a dielectric film, and a lower electrode, wherein the upper electrode or the lower electrode is any one of claims 1 to 5. A semiconductor device comprising an iridium thin film formed by the thin film forming method according to any one of the preceding claims. 9. The semiconductor device according to claim 8, wherein said upper electrode or said lower electrode is a laminated film of said iridium thin film and iridium oxide thin film. 10. The semiconductor device according to claim 8, wherein the upper electrode or the lower electrode is a laminated film of the iridium thin film and a platinum thin film. 11. The semiconductor device according to claim 8, wherein said upper electrode or said lower electrode is a laminated film of said iridium thin film, iridium oxide thin film, and platinum thin film. 12. The semiconductor device according to claim 9, wherein the iridium oxide thin film is an iridium oxide thin film formed by the method for forming a thin film according to claim 1, 2, 3, or 6. Semiconductor device. 13. A method for manufacturing a semiconductor device, comprising the step of forming an iridium thin film or an iridium oxide thin film by the thin film forming method according to claim 1.