JPH10163131A - Method of forming ruthenium oxide film and method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable film forming at high temps. to form a Ru oxide film durable to high temps., by introducing an Ru org. metal compd. and oxidative gas in a film forming region, setting the O partial pressure to specified value, and vapor-phase-depositing an Ru oxide film on a substrate. SOLUTION: A CVD apparatus has a stainless or Al film forming chamber 1 with a gas feed part 4 connected to a first gas feed pipe for feeding O and second gas feed pipe for feeding an Ru-contg. gas. To the gas upstream of the first gas feed pipe 6 an O-bottle is connected through a mass flow controller 6a. An Ru org. metal compd. and oxidative gas are introduced in a film-forming region and the O partial pressure is set to 6Torr or less to grow an Ru oxide film in vapor phase on a substrate W. This allows the Ru oxide film to be formed by the chemical vapor deposition method even at a growing temp. of 500 deg.C or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a ruthenium oxide film and a method for manufacturing a semiconductor device having a ruthenium oxide thin film, and more particularly, to a method for forming a ruthenium oxide film using a raw material of an organometallic compound. The present invention relates to a method and a method for manufacturing a semiconductor device including a process for manufacturing ruthenium oxide.

[0002]

_2. Description of the Related Art Ruthenium oxide film (RuO ₂ ) which is a conductive film
Are applied to devices such as DRAM and FeRAM as capacitor electrodes of thin film capacitors using a ferroelectric / high dielectric substance. Sputtering, as a method of forming RuO ₂
Various methods such as CVD have been employed. A method for producing RuO ₂ by CVD is described in JP-A-6-283438. The CVD uses a CV having a structure as shown in FIG.
This is performed using a D apparatus.

In the CVD apparatus, a vaporized raw material is put into a vaporizer 101, an argon gas (carrier gas) and an oxygen gas are introduced into the heated vaporizer 101, and these gases and the gas of the vaporized raw material are mixed in a reaction chamber 102. To the heated substrate holder 10
3 A film is formed by contacting a gas on the top. For example, 2,2,6,6-tetramethyl-3,5-heptanedioneruthenium (2,2,6,6-Tetramethyl3,5-heptanedioneRutheniu
m, Ru (DPM) ₃ ) is put into the vaporizer 101 and its temperature is set to 12
At 5 ° C., Ar gas is supplied to the vaporizer 101 at a flow rate of 100 ml / min, and oxygen gas is mixed therein at a flow rate of 200 ml / min, and this mixed gas is used as a source gas. Then, the source gas is supplied into the reaction chamber 102 through the gas pipe.

In a reaction chamber 102, a substrate 104 is placed on a stainless steel heating plate (substrate holding table) 103 heated to 360 ° C. by electric heating, and a raw material gas is supplied to the substrate 104 so that Ru is placed on the substrate 104. (DPM) ₃ is thermally decomposed to deposit a RuO ₂ film on the substrate 104. The gas pressure of the reaction system is 5 Torr. The deposition rate of the RuO ₂ film by this film forming method is about 15 nm / min.

[0005]

As described above [0007] In the past, in order to grow the RuO ₂ film, it had gained RuO ₂ film by a low temperature growth of about 120 ° C.. But grown at low temperatures
The RuO ₂ film has an oxide phase other than Ru metal and RuO ₂ on the surface and crystal grain boundaries. Ruthenium (Ru) is an element having a valence of 2 to 8, and its oxides include RuO ₂ and RuO ₄ . RuO ₂ is a solid, whereas RuO ₄ is a gas.When growing a RuO ₂ film by CVD, the substrate temperature is heated to about 500 ° C., and other conditions such as the gas flow rate are described above. When the value is set, a large amount of RuO ₄ is generated and no film is deposited. This is because Ru (DPM) ₃ transported into the reaction chamber 102
At a high temperature of about 500 ° C., it decomposes on the surface of the substrate 104 and reacts with oxygen contained in a large amount of gas to generate RuO ₄ .

Other ruthenium-containing gases include:
2,6-dimethyl-3,5-heptanedioneruthenium (2,6-di
methyl-3,5-heptanedioneRuthenium, Ru (DMHPD) ₃ ),
Bis (sy-penta-dionyl-ruthenium)
clopenta-dienyl) Ruthenium, Ru (C ₅ H ₅ ))
The same result occurs with this raw material. By the way, even if a RuO ₂ film is formed by low-temperature growth, the morphology of the surface of the RuO ₂ film may be rough due to the following reasons.

[0007] The thin film capacitor has a structure in which a dielectric film is sandwiched between electrodes, a RuO ₂ film is used as a lower electrode, and a high dielectric (Ba, Sr) TiO ₃ film is used as the dielectric film. When the structure used is adopted, the morphology of the RuO ₂ film surface becomes rough. This is because (Ba, Sr) TiO _{3 has} a film formation temperature of 500 ° C. or higher, so that when (Ba, Sr) TiO ₃ is grown on the RuO ₂ film, Ru
This is because ruthenium oxide and ruthenium pure metal other than RuO ₂ existing on the surface of the O ₂ film or its crystal grain boundaries react with oxygen at a temperature of 500 ° C. or more and become RuO ₄ , which is easily vaporized.

As described above, when the morphology of the surface of the RuO ₂ film is rough, large irregularities are generated on the surface. Therefore, when a RuO ₂ film is used as an electrode of a thin-film capacitor and a voltage is applied to this electrode, an electric field is locally concentrated on the convex portion of the electrode surface made of RuO ₂ and dielectric breakdown occurs in the dielectric film between the electrodes. It is easy to occur. As described above, when an attempt is made to grow a ruthenium oxide film at a high temperature in an atmosphere with a high oxygen flow rate, RuO ₄ is preferentially generated and the film does not grow on the substrate, and when a ruthenium oxide film is grown at a low temperature. In addition, not only RuO ₂ but also other ruthenium oxides and ruthenium are present in the film, and when the dielectric film is grown thereon, the ruthenium oxide film surface becomes rough.

The present invention has been made in view of such a problem, and a method of forming a ruthenium oxide film capable of forming a film at a temperature of 500 ° C. or more and withstanding a high temperature of 500 ° C. or more, An object of the present invention is to provide a method for manufacturing a semiconductor device including a step of forming ruthenium oxide.

[0010]

[Means for Solving the Problems]

(Means) As described above, as shown in FIG. 1 and FIG.
And a vapor phase growth of the ruthenium oxide film 32 on the substrate W while setting the oxygen partial pressure to 6 Torr or less.

In the method for forming a ruthenium oxide film, the ruthenium organometallic compound may be Ru (DPM) ₃ or Ru (DPM).
MHPD) ₃ or Ru (C ₅ H ₅ ).
In the method for forming a ruthenium oxide film, the oxidizing gas is a gas obtained by mixing one or more of oxygen (O ₂ ), nitrogen dioxide (NO ₂ ), and nitrogen monoxide (N ₂ O). It is characterized by.

In the above method for forming a ruthenium oxide film, the reaction pressure for performing the vapor phase growth is 5 to 10 Torr.
It is characterized by being. In the method for forming a ruthenium oxide film, the substrate temperature during the vapor phase growth may be set at 50.
It is characterized in that the temperature is set to 0 to 600 ° C. The above-described problem is, as exemplified in FIGS. 6 and 7, a step of forming the first metal film 52 directly on the semiconductor substrate 40 or via an insulating film, and a step of forming the first metal film 52 on the first metal film 52. In a method for manufacturing a semiconductor device including forming a capacitor having a step of forming a dielectric film 54 and a step of forming a second metal film 55 on the dielectric film 54, the first metal film 52 And forming at least one of the second metal film 55 comprises a step of introducing a ruthenium organometallic compound and an oxidizing gas, and setting a partial pressure of oxygen to 6 Torr or less to vapor-grow ruthenium oxide. The problem is solved by a method of manufacturing a semiconductor device characterized by the following.

In the method of manufacturing a semiconductor device described above,
The ruthenium organometallic compound is Ru (DPM) ₃ , Ru (DMHP
D) ₃ , or Ru (C ₅ H ₅ ) ₂ .
In the above-described method for manufacturing a semiconductor device, a reaction pressure for performing the vapor phase growth is 5 to 10 Torr. In the above-described method for manufacturing a semiconductor device, the substrate temperature during the vapor phase growth is set at 500 to 600 ° C.

In the method of manufacturing a semiconductor device described above,
The formation of the dielectric film 54 of the capacitor is performed by (Ba, Sr) T
iO ₃ , SrTiO ₃ , Pb (Zr, Ti) O ₃ , PbTiO ₃ , (Pb, Ln) (Zr, Ti)
It is characterized by being performed by forming O ₃ or Bi ₄ Ti ₃ O ₁₂ . The method for manufacturing a semiconductor device described above may further include, before forming the ruthenium oxide forming the first electrode 52 or the second electrode 55, forming a ruthenium film as a base of the ruthenium oxide. Features.

(Operation) Next, the operation of the present invention will be described. According to the present invention, in order to form a ruthenium oxide film, the condition is that a ruthenium organometallic compound and an oxidizing gas are introduced into the film formation region, and the oxygen partial pressure is set to 6 Torr or less. According to this, even when the growth temperature is set to 500 ° C. or more, it is possible to form a ruthenium oxide film by a vapor phase growth method.

When the growth pressure of the ruthenium oxide film is set to 5 to 10 Torr, the surface morphology can be easily adjusted, and the growth rate can be increased to 50 to 10 Torr.
It can be about 100 nm / min. Surface morphology is controlled by adjusting the oxygen pressure. Further, when the surface morphology of ruthenium oxide is smoothed, local electric field concentration is suppressed when the ruthenium oxide film is applied as an electrode of a capacitor.

Further, when the oxygen partial pressure during the growth of ruthenium oxide is set to 6 Torr or less, the ruthenium phase and Ru
There is only a RuO ₂ phase without a ruthenium oxide phase other than O ₂ . Therefore, 5 μm on the ruthenium oxide film
When at 00 ° C. or more high temperature to form an oxide dielectric film, eliminates the generation of RuO ₄ is an oxide of RuO ₂ other than ruthenium oxide and ruthenium at the surface and grain boundaries of ruthenium oxide, the RuO ₄ The morphology of the RuO ₂ film surface does not become rough due to the formation.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 1 shows a CVD apparatus used for forming a film according to an embodiment of the present invention. CV shown in FIG.
The D apparatus has a film forming chamber (chamber) 1 made of stainless steel, aluminum, or the like. In the film forming chamber 1,
A substrate supporting portion 2 for supporting the substrate W, a heater 3 for heating the substrate W, and a gas introducing portion 4 which is a space for introducing a reactive gas.
And a shower plate 5 having a large number of holes for discharging the gas in the gas introduction unit 4 toward the substrate support unit 2.

A first gas supply pipe 6 for introducing oxygen and a second gas supply pipe 7 for introducing a ruthenium-containing gas are connected to the gas introduction section 4. An oxygen cylinder (not shown) is connected to a gas upstream side of the first gas supply pipe 6 via a mass flow controller (MFC) 6a. The upstream end of the second gas supply pipe 7 is inserted into the space of the ruthenium raw material container 11 via on-off valves 8 and 10 and a flow control valve 9.

The ruthenium raw material container 11 is heated to a _first temperature T ₁ by a thermostat 12, and the powdery ruthenium raw material R stored therein is heated and sublimated. In order to send the sublimated ruthenium raw material R into the second gas supply pipe 7, the ruthenium raw material R container 1
A third gas supply pipe 13 for introducing an inert carrier gas such as argon gas is connected to 1 via an on-off valve. On the gas downstream side of the third gas supply pipe 13, on-off valves 14, 15 and a mass flow controller (MF)
C) An argon gas cylinder (not shown) is connected through 16.

As the ruthenium solid raw material stored in the ruthenium raw material container 11, for example, Ru (DPM) ₃ , Ru (DMHPD)
₃ , Ru (C ₅ H ₅ ) and the like. Further, in the film forming chamber 1, a first exhaust pipe 17 is connected to the substrate support section 2 on the side opposite to the gas introduction section 4, and the pressure adjustment connected to the first exhaust pipe 17 is performed. Valve 18, mechanical booster pump 19
The inside of the film forming chamber 1 is depressurized to a predetermined pressure by the dry pump 20.

The second gas supply pipe 7 has an on-off valve 2
The second exhaust pipe 22 is connected through 1. Also,
A bypass pipe 23 is connected to the second gas supply pipe 7 and the third gas supply pipe 13, and an on-off valve 24 is connected to the bypass pipe 23. The on-off valve 24 is opened and the on-off valve 8, By closing 14 and continuing to supply the carrier gas into the second gas supply pipe 7 through the third gas supply pipe 13, the ruthenium-containing gas in the second gas supply pipe 7 is supplied to the first gas supply pipe 6. Alternatively, it is configured to discharge through the second exhaust pipe 22.

The second and third gas supply pipes 7, 13 and the second
Around the exhaust pipe 22 and the gas introduction part 4
Heater 25 for heating the temperature T ₂ higher second than the temperature T ₁ of the and is arranged, thereby, a gas introduction portion 4 pipe, a second exhaust pipe 22, the second and third gas supply Condensation of the gaseous raw material in the tubes 7 and 13 is suppressed.

The reference numeral 26 in the figure denotes the first exhaust pipe 17.
, Which is configured to input data of the measured pressure to the pressure regulating valve 18. Reference numeral 27 denotes a second pressure gauge connected to the second gas supply pipe 7, and the flow rate at the flow control valve 9 attached to the second gas supply pipe 7 is set to a predetermined value according to the pressure. It is adjusted to become.

Using such a CVD apparatus, a ruthenium film and a ruthenium oxide film were formed on the substrate W, and the phase and surface morphology of the ruthenium oxide film were examined. First, the substrate W on which a film is to be formed is attached to the substrate support 2, and then the mechanical booster pump 19 and the like are driven to reduce the pressure in the film forming chamber 1 to 1 to 10 Torr during film formation, and the heater 3 is used. The substrate W is heated to a temperature of 500 to 600C.

Further, when the ruthenium source container 11 is sealed by housing the powdered Ru (DPM) _3, further heating retain Ru (DPM) ₃ at 200 ° C. which is the sublimation temperature by a thermostat 12, Ru (DPM) ₃ sublimates. When argon (Ar) gas is supplied as a carrier gas into the ruthenium raw material container 11 through the third gas supply pipe 13 at a flow rate of about 300 sccm,
The sublimated Ru (DPM) ₃ is supplied to the second gas supply pipe 7 together with Ar gas.
Through the gas inlet 4.

In this case, when the second gas supply pipe 7 is heated by the heater 25 to 210 ° C., which is 10 ° C. higher than the sublimation temperature of the ruthenium raw material R, the condensation of the raw material in the pipe is suppressed, and the raw material is efficiently formed. It is supplied into the chamber 1. And
When a mixed gas of Ru (DPM) ₃ and argon is supplied to the substrate W through the holes of the gas introduction unit 4 and the gas shower plate 5 in the film forming chamber 1, the substrate ₃ is decomposed by the heat from the heater 3, as shown in FIG. A ruthenium (Ru) film 31 as shown in FIG.

After the Ru film 31 is formed, when oxygen (O ₂ ) gas is introduced into the gas introducing section 4 through the first gas supply pipe 6 at a constant flow rate within the range of 10 to 50 sccm by the mass flow controller, the gas is introduced. Oxygen and Ru (D
PM) ₃ and Ar are mixed. The mixed gas is supplied onto the substrate W through the holes of the gas shower plate 5. The present inventors,
When the phase of the ruthenium oxide film was examined by changing the growth pressure and the oxygen partial pressure, the ruthenium oxide film 32 could be formed depending on the conditions as shown in FIG. 2 (b). When the phases of the ruthenium oxide film 32 were examined, it was found that not only the RuO ₂ phase but also the Ru phase were included due to the difference in oxygen partial pressure. Further, it was found that the surface morphology of the ruthenium oxide film 32 was changed by changing the oxygen partial pressure.

For example, the pressure in the film forming chamber 1 is reduced to 10 Torr, the substrate temperature is set to 500 ° C., and the oxygen partial pressure is set to 0.05.
When the oxygen partial pressure was changed to 0.5 Torr, a result as shown in FIG. 3 was obtained. At an oxygen partial pressure of 0.1 Torr or more, a RuO ₂ film containing no unoxidized Ru phase was formed, and is not shown in FIG. But,
A RuO ₂ film containing no Ru phase was formed up to an oxygen partial pressure of 5 Torr, but a ruthenium oxide film was not formed at an oxygen partial pressure higher than 5 Torr.

That is, when the growth pressure is 10 Torr and the oxygen partial pressure is lower than 0.1 Torr, the ruthenium oxide film 32
It was found that unoxidized Ru phase was contained. When a high-dielectric film, which is a composite oxide, is grown on a ruthenium oxide film containing a Ru phase, the ruthenium phase (Ru phase) is oxidized during the formation of the high-dielectric, or the Ru phase becomes oxygen in the high-dielectric. As a result, a ruthenium oxide other than RuO ₂ is produced. When the ruthenium is oxidized, the morphology of the ruthenium surface becomes rough, and the electric field is concentrated at the convex portions generated when a voltage is applied to the capacitor electrode. In addition, oxidation of ruthenium by oxygen in the high dielectric substance becomes a film lacking oxygen and deteriorates the film quality.

When a high dielectric oxide, for example, (Br, Sr) TiO ₃ is degraded, a decrease in dielectric constant and an increase in leak current are caused, and (B
The (r, Sr) TiO ₃ film does not function sufficiently as a dielectric film of the capacitor. When the specific resistance of the RuO ₂ film formed at an oxygen partial pressure of 0.05 to 5.0 Torr was measured by a 4-deep terminal method, it was 50 to 60 μΩcm, which was almost the same value as the bulk crystal.

FIG. 3 was measured by the X-ray diffraction method (XRD), and the phase of the ruthenium oxide film described below was also measured by the same method. Next, the substrate temperature was set to 600
When the ruthenium oxide film 32 was grown in the same manner as in FIG. 2B by changing the oxygen partial pressure while setting the growth pressure at 10 ° C. and 10 Torr, the results shown in Table 1 were obtained, and 0.1 to 6.0.
At an oxygen partial pressure of Torr, a ruthenium oxide film 32 containing no unoxidized Ru phase grew. However, the oxygen partial pressure is 0.07 To
It was found that a film containing a Ru phase was formed below rr, and a ruthenium oxide film did not grow when the partial pressure of oxidation became 7.0 Torr.

[0033]

[Table 1]

As described above, when the growth chamber pressure is set to 10 Torr and the substrate temperature is set in the range of 500 to 600 ° C., the Ru phase is not contained at the oxygen partial pressure of 0.1 to 6.0 Torr.
The growth of RuO ₂ film became possible. Next, a conventional RuO ₂ film formed by sputtering, and RuO ₂ film containing no Ru phases grown in the above conditions were separately formed by a CVD method, these samples, the oxygen gas flow rate 5 slm, atmospheric pressure ( Heating was performed at a temperature of 500 ° C. for 60 minutes in an atmosphere of 760 Torr). The conventional RuO ₂ film formed by sputtering has a substrate heating temperature of 3
Prepared at 50 ° C. The thickness of each sample is 100 nm. The surface morphology of each sample changed as shown in Table 2.

[0035]

[Table 2]

According to Table 2, it is found that the RuO ₂ film containing no Ru phase formed by the CVD method has a small change in surface morphology due to heating after growth. on the other hand,
According to the RuO ₂ film formed by sputtering, the surface morphology becomes large, and when this RuO ₂ film is used as an electrode of a capacitor, the unevenness of the electrode surface becomes large, electric field concentration occurs locally, and dielectric breakdown easily occurs. Become.

The surface morphology occurs because pure ruthenium metal existing on the RuO ₂ film surface and the RuO ₂ crystal grain boundary, or ruthenium oxide other than RuO ₂ is oxidized to RuO ₂ and RuO _4.
And precipitates or vaporizes on the surface and the grain boundaries. RuO ₂ is stably present even when heated at 500 ° C. in an oxygen atmosphere, but pure ruthenium metal and ruthenium oxide other than RuO ₂ are oxidized.

Next, the growth pressure in the growth chamber was set to 5 Torr, the oxygen partial pressure was changed to form a ruthenium oxide film, and the phase of the ruthenium oxide film was examined. As ruthenium raw material
Ru (DPM) ₃ was used, and argon gas was used as the carrier gas. In this case, the substrate temperature was set to 600 ° C.
Table 3 shows the phases of the ruthenium oxide film grown under these conditions.
It became as shown in. According to Table 3, the oxygen partial pressure was 2.5
At Torr, it was found that the RuO ₂ film did not grow.

[0039]

[Table 3]

According to Table 3, by setting the growth pressure at 5 Torr and the oxygen partial pressure within the range of 0.1 to 2.0 Torr, a RuO ₂ film containing no unoxidized Ru phase was formed. From the above, when Ru (DPM) ₃ is used as the ruthenium raw material, when the substrate temperature is 600 ° C. and the growth pressure is in the range of 5 to 10 Torr, the oxygen partial pressure is set in the range of 0.1 to 6.0 Torr. As a result, a RuO ₂ film containing no Ru phase is grown.

Further, Ru (DPM) ₃ was introduced into the growth chamber 1 with argon gas, and a RuO ₂ film was grown at a substrate temperature of 600 ° C. and a growth pressure of 5 Torr and 10 Torr.
FIG. 4 shows the relationship between the oxygen partial pressure and the surface morphology (unevenness). According to FIG. 4, if the growth pressure is further reduced below 5 Torr, it is difficult to set the surface morphology to a desired size by adjusting the oxygen partial pressure. On the other hand, when the growth pressure to 10 Torr, because the adjustment of the surface morphology is relatively easy, the growth rate of the RuO ₂ film is reduced at higher growth pressures undesirable.

Next, instead of Ru (DPM) ₃ as a reaction gas,
Using Ru (C ₅ H ₅ ) ₂ , a substrate temperature of 600 ° C. and a growth pressure of 5
When the relationship between the surface morphology (irregularities) at 10 Torr and the oxygen partial pressure was examined, the results shown in FIG. 5 were obtained. In other words, it was found that the smaller the growth pressure, the more difficult it was to adjust the size of the surface morphology.
Below Torr is not preferred.

According to Tables 1 and 3, as the oxygen partial pressure increases, the RuO ₂ film does not grow. this is,
Raw material gas in which Ru (DPM) ₃ or Ru (C ₅ H _{5) 2} is decomposed and the oxidizing gas, when generating the ruthenium oxide react to than the production of RuO ₂ than RuO ₂ generation of RuO ₄ Is superior, and the film does not grow and the product is vaporized. Next, Ru (C ₅ H ₅ ) ₂ was used instead of Ru (DPM) ₃ as a reaction gas, the substrate temperature was set to 600 ° C., and the growth pressure was set to 5 Torr. Table 4 shows the relationship. Also,
Table 5 shows the oxygen partial pressure and the phase of the ruthenium oxide film when the same reaction gas was used, the same substrate temperature was used, and the growth pressure was 10 Torr.

[0044]

[Table 4]

[0045]

[Table 5]

From Tables 4 and 5, it can be seen that Ru (C ₅ H ₅ ) ₂
Although a RuO ₂ film containing no phase was able to be formed, the oxygen partial pressure for obtaining a RuO ₂ film containing no Ru phase was reduced by an order of magnitude compared to the case where Ru (DPM) ₃ was used. It was found that it was difficult to adjust the oxygen partial pressure to form a RuO ₂ film containing no oxygen. When Ru (DMHPD) ₃ was used as the raw material gas, the same results were obtained as when Ru (DPN) ₂ was used. (Explanation of Capacitor Forming Step) Next, a description will be given of a step of forming a thin film capacitor using the above-described RuO ₂ film as an electrode in a DRAM cell manufacturing step.

First, as shown in FIG. 6A, a LO is formed around the transistor formation region on the surface of the silicon substrate 40W.
The field oxide film 41 is formed by the COS method. Next, the gate electrodes 43 of the MOS transistors 44 and 45 are formed in the transistor formation region via the gate oxide film 42. The gate electrode 43 extends on the field oxide film 41 and also serves as a word line. On both sides of the gate electrode 43, impurity diffusion layers 46a and 46b serving as sources and drains of the MOS transistors 44 and 45 are formed. In FIG. 6A, one of the two adjacent MOS transistors 44 and 45 has the same impurity diffusion layer 44, and the impurity diffusion layer 44 is connected to the bit line BL. Note that the gate electrode 43 is covered with an insulating film 47 such as SiO ₂ .

[0048] In this state, as shown in FIG. 6 (b), the MOS transistors 44, 45 and the field oxide film 41 was covered with an interlayer insulating film 48 such as SiO _2, MO
A contact hole 48 is formed above impurity diffusion layer 46b on the side of S transistors 44 and 45 not connected to bit line BL.
a is formed. Thereafter, as shown in FIG. 6C, after a plug 49 made of tungsten or polysilicon is formed in the contact hole 48a, a titanium (Ti) film 50 is formed.
And a titanium nitride (TiN) film 51 are formed by sputtering. These Ti layer 50 and TiN layer 51 function as a barrier metal. Typical deposition conditions for the Ti film 50 are a deposition pressure of 1 mTorr, a deposition substrate temperature of 300 ° C., and a flow rate of argon gas introduced into the deposition atmosphere of 40 sccm. In the case of the TiN film 51, the film is formed by introducing nitrogen gas at a flow rate of 30 sccm together with argon gas introduced under the conditions for forming the Ti film 50.

Next, as shown in FIG. 6 (d), as the storage electrode 52 of the capacitor, using the above-described CVD apparatus,
A Ru film 52a and a RuO ₂ film 52b are formed on the N film 51.
The Ru film 52a is prevented from reacting with the lower layer by the Ti layer 50 and the TiN layer 51 functioning as a barrier metal. RuO ₂
As described above, the formation of the film 52b is set to a condition not including the Ru phase.

Subsequently, a first resist 53 is formed on the RuO ₂ film surface.
Is applied, and this is exposed and developed, and is left only in the plug 49 and its surrounding area. Then, as shown in FIG. 6E, using the first resist 53 as a mask, the RuO ₂ film 52 not covered with the mask is formed by ion milling.
b, Ru film 52a, TiN film 51 and Ti film 50 are etched. The conditions of ion milling were as follows: acceleration voltage 1 kV, pressure 2
× 10 ^-4 Torr, the incident angle of ions is 15 degrees with respect to the normal direction of the film, and the etching time is 7 minutes and 30 seconds.

After the ion milling, the first resist 5
After stripping 3, as shown in FIG. 7 (a), a high dielectric (Ba, Sr) TiO ₃ is formed as a dielectric film 54 to a thickness of about 180 nm by sputtering. Regarding the sputtering conditions, the sputtering pressure was 25 mTorr, and the substrate temperature was not heated.
The power is 1 kW, and the sputtering time is 5 minutes. Next, FIG.
As shown in (b), a Ru film or Ru
An O ₂ film or a laminated film of these (which may be any lower side) is formed. The formation conditions are the same as those for forming the storage electrode 52.

After that, a second resist 56 is applied to the surface of the counter electrode 55, and is exposed and developed to leave the second resist 56 in a region wider than the storage electrode 52. Then, as shown in FIG. 7C, using the second resist 56 as a mask, the counter electrode 55 and the dielectric film 54 not covered with the mask are etched by ion milling. Regarding the conditions of ion milling, the accelerating voltage is 1k
V, the pressure is 2 × 10 ⁻⁴ Torr, the incident angle of ions is 15 degrees with respect to the normal direction of the film, and the etching time is 9 minutes.

By this patterning, the shape of the capacitor is
Finish the configuration. Next, SiO 2 is deposited by thermal CVD._TwoMembrane 57
Formed to a thickness of 00 nm_TwoCondensation by membrane 57
Cover the sensor. That SiO_TwoAs a growth condition of the film 57, Si
H_FourAnd NO _TwoSubstrate temperature of 300 ° C and pressure using
10 Torr and the deposition time is 10 minutes.

Thereafter, an opening (not shown) is formed in the SiO ₂ film 57 using a resist mask and the RIE method.
A titanium nitride film is formed by sputtering on the SiO ₂ film and its opening, and the wiring 58 is formed by patterning the titanium nitride film. Through the above process, a DRAM cell having a capacitor having a thin film stack structure is manufactured.
The electrical characteristics of the capacitor were a current density of 10 ⁻⁸ A / cm ² and a relative dielectric constant of 200 when 2 V was applied.

Next, a process of connecting a capacitor and a MOS transistor by local interconnection will be described. First, a MOS transistor similar to that shown in FIG. 6A is formed. Next, as shown in FIG. 8A, a Ru film 61a and a RuO ₂ film 61b are sequentially formed on the whole, and then a Ru film 6 is formed by using a resist mask (not shown) and ion milling.
The 1a and the RuO ₂ film 61b are patterned and left on the insulating film 60 around the MOS transistor to form the storage electrode 61.

These films are grown using the above-described CVD apparatus, and the Ru film 52a and the RuO ₂ film 52b shown in FIG.
The film is formed under the same film forming conditions and the same film thickness. Further, the RuO ₂ film 61b is formed under the above-described conditions such that the Ru phase does not exist. The conditions of the ion milling method were as follows: an acceleration voltage of 1 kV, a pressure of 2 × 10 ⁻⁴ Torr, an ion incident angle of 15 ° with respect to the normal direction of the film, and an etching time of 7 minutes 3
0 seconds.

Subsequently, as shown in FIG. 8B, a dielectric film 62 made of Pb (Zr, Ti) O _{3 as} a ferroelectric is formed to a thickness of 180 nm by Rf sputtering. As for the sputtering conditions, the sputtering pressure is 25 mTorr, the substrate W is at room temperature, the power is 1 kW, and the sputtering time is 5 minutes. Next, as shown in FIG. 8 (c), a counter electrode 63 made of a laminated film of Ru and RuO ₂ (whichever may be on the upper side) or a Ru film or a RuO ₂ film is formed. The film forming conditions are as follows:
1 is the same as that of the film. Subsequently, a resist 54 is applied on the counter electrode 63, and is exposed and developed to be left on and around the storage electrode 61.

Thereafter, as shown in FIG. 9A, the counter electrode 63 and the dielectric film 62 exposed from the resist 64 are removed by etching. The etching is performed by an ion milling method with an acceleration voltage of 1 kV and a pressure of 2 × 10 ^−4.
Torr, the incident angle of ions is 15 degrees with respect to the normal direction of the film,
The etching time is 9 minutes. The resist 54 after removal, as shown in FIG. 9 (b), the SiO ₂ film 65 on the entire CV
Formed to a thickness of 200nm by Method D, followed by, SiO ₂ film 6
5, first to third through holes 65 a to 65 c are formed on the counter electrode 65 of the capacitor and on the pair of impurity diffusion layers 46 a and 46 b of the MOS transistor.

The conditions for forming the SiO ₂ film 65 are as follows: SiH ₄ gas and N ₂ O
Using gas, substrate temperature 300 ℃, growth pressure 10To
rr, the deposition time is 10 minutes. Next, after forming a titanium nitride film on the whole, as shown in FIG. 9 (c), the titanium nitride film is patterned to form a capacitor from the second through hole 65b on one impurity diffusion layer 46b of the MOS transistor. First through-hole 65 on counter electrode 65
to form a local interconnection 66 that extends to a, to form a the bit lines BL ₁ to be connected to the third through hole 65c on the other of the impurity diffusion layers 46a of the MOS transistor. Further, an interlayer insulating film 67 is entirely formed, and a wiring 68 made of TiN is formed thereon.

Ru film used as an electrode for a capacitor
Thickness 10-50nm, RuO_TwoThe film should be 50-100 nm
preferable. The storage electrode of the capacitor described above, facing
One of the electrodes may be formed from a metal such as platinum.
No. Note that the dielectric film used for the above capacitor is
(Ba, Sr) TiO _Three, Pb (Zr, Ti) O_ThreeBesides, Sr
TiO_Three, PbTiO_Three, (Pb, Ln) (Zr, Ti) O_Three, Bi_FourTi_ThreeO₁₂Using
Is also good. In addition, as a counter electrode, a Ru film and RuO_TwoSubstitute for membrane
Alternatively, a platinum film formed by sputtering may be used. Further
In addition, not only oxygen but also oxygen (O_Two),
Nitrogen dioxide (NO_Two ), Nitric oxide (N_TwoO) a kind of
Alternatively, the same effect can be obtained even with a gas obtained by mixing a plurality of gases.
can get.

[0061]

As described above, according to the present invention, in order to form a ruthenium oxide film, a ruthenium organometallic compound and an oxidizing gas are introduced into the film formation region, and the oxygen partial pressure is reduced to 6 Torr.
Since the conditions are set as follows, it is possible to form a ruthenium oxide film by a vapor phase growth method even when the growth temperature is set to 500 ° C. or higher.

When the growth pressure of the ruthenium oxide film is set at 5 to 10 Torr, the surface morphology can be easily adjusted, and the growth rate can be increased to 50 to 10 Torr.
It can be about 100 nm / min. Surface morphology can be controlled by adjusting the oxygen pressure. Also, if the surface morphology of ruthenium oxide is reduced,
When the ruthenium oxide film is used as an electrode of a capacitor, local electric field concentration is suppressed.

Further, when the oxygen partial pressure during the growth of ruthenium oxide is set at 6 Torr or less, the ruthenium phase in the film is not contained, and when the dielectric film is formed thereon at a high temperature of 500 ° C. or more, the surface of the ruthenium oxide is reduced. In addition, generation of gaseous RuO ₄ from the crystal grain boundaries becomes difficult, and generation of rough surface morphology due to heat of the ruthenium oxide film can be suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for growing a ruthenium film and a ruthenium oxide film grown in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the growth of a ruthenium film and a ruthenium oxide film in the embodiment of the present invention.

FIG. 3 is a diagram showing an analysis result of a phase of a ruthenium oxide film by an X-ray diffraction method in the embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the surface morphology of a ruthenium oxide film formed using Ru (DPM) ₃ as a raw material and the oxygen partial pressure in the embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a surface morphology of a ruthenium oxide film formed using Ru (CP) ₂ as a raw material and an oxygen partial pressure in the embodiment of the present invention.

FIG. 6 is a cross-sectional view (part 1) illustrating a manufacturing process of a first DRAM cell including a growth process of a ruthenium film and a ruthenium oxide film in the embodiment of the present invention.

FIG. 7 is a cross-sectional view (part 2) illustrating a process for manufacturing a first DRAM cell including a process for growing a ruthenium film and a ruthenium oxide film in the embodiment of the present invention.

FIG. 8 is a cross-sectional view (part 1) illustrating a process for manufacturing a second DRAM cell including a process for growing a ruthenium film and a ruthenium oxide film in the embodiment of the present invention.

FIG. 9 is a cross-sectional view (part 2) illustrating a process for manufacturing a second DRAM cell including a process for growing a ruthenium film and a ruthenium oxide film in the embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a conventional apparatus for growing a ruthenium oxide film.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Film-forming chamber 2 Substrate support part 3 Heater 4 Gas introduction part 5 Shower plate 11 Ruthenium material container 31 Ru film 32 RuO ₂ film

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI H01L 27/108 H01L 27/10 651 21/8242

Claims (11)

[Claims] 1. A ruthenium oxide film, comprising: introducing a ruthenium organometallic compound and an oxidizing gas into a film forming region; and setting a partial pressure of oxygen to 6 Torr or less to vapor-grow a ruthenium oxide film on a substrate. Forming method. 2. The ruthenium organometallic compound is Ru (DP
_2. The method for forming a ruthenium oxide film according to claim 1, wherein the method is any one of M) ₃ , Ru (DMHPD) ₃ , and Ru (C ₅ H ₅ ) ₂ . 3. The method according to claim 1, wherein the oxidizing gas is a gas obtained by mixing one or more of oxygen, nitrogen dioxide, and nitric oxide. 4. The reaction pressure for performing said vapor phase growth is 5 to 5.
2. The method for forming a ruthenium oxide film according to claim 1, wherein the pressure is 10 Torr. 5. The method according to claim 1, wherein said substrate temperature during said vapor phase growth is 500.
2. The method for forming a ruthenium oxide film according to claim 1, wherein the temperature is set to a temperature in a range from to 600 [deg.] C. 6. A step of forming a first metal film directly on a semiconductor substrate or via an insulating film, a step of forming a dielectric film on the first metal film, and a step of forming a dielectric film on the first metal film. A method of manufacturing a semiconductor device including forming a capacitor having a step of forming a second metal film thereon, wherein the step of forming at least one of the first metal film and the second metal film comprises: ruthenium A method for manufacturing a semiconductor device, comprising a step of introducing an organometallic compound and an oxidizing gas, and setting a partial pressure of oxygen to 6 Torr or less to vapor-grow ruthenium oxide. 7. The ruthenium organometallic compound is Ru (DP
7. The method according to claim 6, wherein the semiconductor device is any one of M) ₃ , Ru (DMHPD) ₃ , and Ru (C ₅ H ₅ ) ₂ . 8. The reaction pressure for performing said vapor phase growth is 5 to 5.
7. The method according to claim 6, wherein the pressure is 10 Torr. 9. The method according to claim 1, wherein said substrate temperature during said vapor phase growth is 500.
7. The method for forming a ruthenium oxide film according to claim 6, wherein the temperature is set to a temperature in a range from to 600 [deg.] C. 10. The formation of the dielectric film of the capacitor includes (Ba, Sr) TiO ₃ , SrTiO ₃ , Pb (Zr, Ti) O ₃ , PbTiO ₃ ,
b, Ln) (Zr, Ti ) O 3 or Bi ₄ Ti ₃ O ₁₂ formation method of ruthenium oxide film according to claim 6, characterized in that by forming. 11. The method according to claim 6, further comprising a step of forming a ruthenium film as a base of said ruthenium oxide before forming said ruthenium oxide forming said first electrode or said second electrode. A method for forming a ruthenium oxide film as described above.