WO2004075296A1

WO2004075296A1 - Method for manufacturing ferroelectric capacitor

Info

Publication number: WO2004075296A1
Application number: PCT/JP2003/001773
Authority: WO
Inventors: Mineharu Tsukada; Hideki Yamawaki
Original assignee: Fujitsu Limited
Priority date: 2003-02-19
Filing date: 2003-02-19
Publication date: 2004-09-02
Also published as: JPWO2004075296A1

Abstract

A nitrogen gas is supplied along with a Ru material into an MOCVD chamber. By maintaining this state, a Ru film is formed. While reducing the nitrogen gas to 20 volume%, supply of 80 volume% of oxygen gas as a reaction gas is started, supply of a Bi material is also started, and immediately after that the supply of the Ru material is stopped. As a result, the quantity of Bi in the MOCVD chamber increases, and that of Ru material decreases. During this, a lower conductive compound film is formed. After the introduction of the Ru material into the MOCVD chamber is completely stopped, supply of a Ti material and a La material is started while maintaining the supply of the Bi material. By maintaining this state, a BLT film is formed. The lower conductive compound film suppresses diffusion of Ru into the BLT film, thereby preventing an increase of the leak current.

Description

Manufacturing method of ferroelectric capacitor

The present invention relates to a method of manufacturing a ferroelectric capacitor suitable for manufacturing a Bi layer thin film capacitor used for a ferroelectric nonvolatile memory (FRAM) or the like. Background art

A ferroelectric nonvolatile memory (FRAM) is provided with a thin film capacitor. Conventionally, in manufacturing this thin film capacitor, first, a lower electrode film is formed by a sputtering method, and then a ferroelectric film is formed by a sol-gel method, a sputtering method, or a MOCVD method. Is formed. As the ferroelectric film, a PZT-based ferroelectric film and a Bi-layered ferroelectric film are mainly used.

Also, as the electrode material of a PZT thin film capacitor and B i layer-type thin film capacitor, P t, I r, I R_〇 _2, etc. actually used. Numerous studies on these have been made. At the research stage of PZT-based thin film capacitors in the mid-1990s, Ru-based (including Ru 電極₂ ) electrode materials were also studied. However, if a Ru-based electrode material is used, it is difficult to control the leakage of the capacitor, and it has not been put to practical use. This will react with R u in P b and the electrode film in the ferroelectric, conductive I匕合of such pie port Kuroa structure as _{_{_{P b 2 R u 2 O 6}}} ~ 7 are generated That's why. However, Ru has the advantage that its bullion price is lower than that of Pt and Ir.

Generally, when a PZT film is formed, Pb is contained in the film in an amount larger than the stoichiometric composition. This excess Pb plays an important role in the early stage of crystallization, and also has a role to supplement the evaporation of Pb at high temperature, and exists mainly at the grain boundaries in the PZT film after crystallization. I do. For such a ferroelectric film, if Ru exists at the interface with the PZT film at a high temperature? Is it the above mentioned in response to 1? 1) ₂ 11 ₁₂ ₂₆ to ₇ are generated, and a conductive path is formed at the grain boundary, and the leakage current increases. Japanese Patent No. 3 0 9 5 5 7 4 Pat, this phenomenon for foul trick, between the ferroelectric layer made of the electrode and the PZT consisting of R u 0 _2, deliberately P b _₂ R u ₂技術 A technique for forming a film consisting of ₆ to ₇ is described.

Recently, there has been a demand for reduction of manufacturing time and cost of manufacturing equipment. However, when a Pt film or the like is formed as an electrode film by a sputtering method, it is necessary to transfer a wafer between steps for forming a lower electrode film, a strong dielectric film, and an upper electrode film. A chamber for forming an electrode film and a chamber for forming a ferroelectric film are required. For this reason, such a manufacturing method has limitations in shortening the manufacturing time and reducing the cost of the manufacturing equipment.

Further, when a Ru-based electrode film is used, as described above, there is a drawback that the leak current increases. This drawback is described in Japanese Patent No. 3,095,574. It has not been solved by technology. That is, in this manufacturing method, after forming the R U_〇 ₂ film, a PZT film is formed thereon, these interfaces by Aniru, but forms a _{_{_{P b 2 R u 2 0 6}}} ~ 7, In such a method, an increase in leakage current is inevitable due to grain boundary diffusion during annealing. This phenomenon, in the case of using B i layered system ferroelectric film in place of the PZT system ferroelectric film likewise, B i ₂ R u ₂ 0 of ₇ _ _x such pies port Croix structure Of the conductive compound may be generated.

Patent Document 1

Patent No. 3 095 5 7 4 Disclosure of the Invention

SUMMARY OF THE INVENTION The present invention has been made in view of the difficult problem, and provides a method of manufacturing a ferroelectric capacitor in which a ferroelectric film and an electrode film can be continuously formed in the same chamber. The purpose is to do.

As a result of intensive studies, the inventor of the present application has come up with the following aspects of the invention.

A method for manufacturing a ferroelectric capacitor according to the present invention is directed to a method for manufacturing a ferroelectric capacitor including a Bi layered ferroelectric film.

In the first invention, first, a gas containing a first metal element is placed in a CVD chamber. To form a lower electrode film containing the first metal element. Next, while continuously introducing the gas containing the first metal element into the CVD chamber, further introducing a gas containing Bi and O into the CVD chamber. A first conductive compound film containing a metal element and Bi is formed. Next, the introduction of the first metal element into the CVD champer is stopped. After that, while continuously introducing a gas containing Bi and O into the CVD chamber, the ferroelectric material excluding Bi among the metal elements constituting the Bi layered ferroelectric film is further added. A gas containing a metal element for a film is introduced to form the Bi layered ferroelectric film on the first conductive compound film. Subsequently, introduction of Bi and the metal element for the ferroelectric film into the CVD chamber is stopped. Then, an upper electrode film is formed on the Bi layered ferroelectric film.

In the second invention, first, a lower electrode film is formed. Next, into the CVD champer, a gas containing Bi and a metal element for a ferroelectric dielectric film excluding Bi among metal elements constituting the Bi-layered ferroelectric film and O is introduced. Then, the Bi layered ferroelectric film is formed on the lower electrode film. Next, the introduction of the metal element for a ferroelectric film into the CVD chamber is stopped. Thereafter, while continuously introducing a gas containing Bi and O into the CVD chamber, a gas containing a second metal element is introduced, and the gas containing the second metal element is introduced onto the Bi layered ferroelectric film. Forming a second conductive compound film containing the second metal element and Bi. Subsequently, the introduction of Bi into the CVD chamber is stopped. Then, a gas containing the second metal element is continuously introduced into the CVD champer to form an upper electrode film containing the second metal element on the second conductive compound film. .

As described above, in the conventional manufacturing method, there is a possibility that the metal element in the electrode film such as Ru reacts with the Bi in the Bi-layered ferroelectric film to increase the leakage current. In the present invention, an electrode film (lower electrode film and / or upper electrode film) and a ferroelectric film are formed continuously in the same CVD chamber, and a conductive compound is formed between these films. A material film is formed. Thus, by forming the conductive compound film by the CVD method, it is possible to complete the reaction between Bi and the metal element in this film, and to prevent the reaction in the ferroelectric film. it can. As a result, an increase in leakage current is prevented. Can be stopped. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a timing chart showing a method for manufacturing a ferroelectric memory according to the first embodiment of the present invention.

2A to 2G are cross-sectional views illustrating a method of manufacturing the ferroelectric memory according to the first embodiment of the present invention in the order of steps.

FIG. 3 is a cross-sectional view showing a ferroelectric capacitor manufactured in the first embodiment of the present invention.

FIG. 4 is a timing chart showing a method for manufacturing a ferroelectric memory according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a method for manufacturing a ferroelectric memory according to the second embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a ferroelectric capacitor manufactured in the second embodiment of the present invention. ·

FIG. 7 is a timing chart showing a method for manufacturing a ferroelectric memory according to the third embodiment of the present invention.

FIG. 8 is a cross-sectional view illustrating a method for manufacturing a ferroelectric memory according to the third embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a ferroelectric capacitor manufactured in the third embodiment of the present invention.

FIG. 10 is a timing chart showing a modification of the third embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a method for manufacturing a ferroelectric capacitor according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.

(First Embodiment)

First, a first embodiment of the present invention will be described. In this embodiment, the ferroelectric A ferroelectric memory including a capacitor is manufactured. FIG. 1 is a timing chart showing a method for manufacturing a ferroelectric memory according to the first embodiment of the present invention. 2A to 2G are cross-sectional views showing the same manufacturing method in the order of steps, and FIG. 3 is a cross-sectional view showing the ferroelectric capacitor manufactured in the first embodiment.

First, as shown in FIG. 2A, an element isolation region 12 is formed on the surface of a semiconductor substrate 11 such as a silicon substrate by, for example, STI (shallow trench isolation). Next, a well 13 is formed on the surface of the semiconductor substrate 11 in the element active region partitioned by the element isolation region 12. Subsequently, a gate insulating film 17, a gate electrode 18, a silicide layer 19, a low-concentration diffusion layer 15, a sidewall 20, and a high-concentration diffusion layer 16 are formed on the surface of the well 13. The S transistor 14 is formed. Each MOS transistor 14 has two high-concentration diffusion layers 16 for source and drain, one of which is shared by the two MOS transistors 14.

Next, a silicon oxynitride film 21 is formed on the entire surface so as to cover the MOS transistor 14, and a silicon oxide film 22 is further formed on the entire surface by, for example, an organic CVD method. The silicon oxynitride layer 21 is formed to prevent the gate insulating film 17 and the like from forming hydrogen when the silicon oxide film 22 is formed. Thereafter, a contact hole reaching between the high concentration diffusion layers 16 is formed in the silicon oxide film 22 and the silicon oxynitride film 21 to open a plug contact portion. Then, after forming a laminated film composed of a 50 nm TiN film and a 30 nm Ti film as a glue film 23 in the contact hole, a W film is buried by, for example, the CVD method, and the CMP ( The W plug 24 is formed by carrying out and carrying out. Then, as shown in FIG. 2 B, the entire surface R u film (lower electrode film) 2 5, the lower conductive compound film 2 5 a及Pi BLT ((B i, L a ) 4 T i 3 0 1 2) The film 26 is formed continuously by the MOCVD method in the same champer.

Here, a method for forming these B25, 25a and 26 will be described. As these raw materials (precursors), for example, those shown in Table 1 are used. Further, as the solvent, for example, n-hexane is used. It is desirable to use a MOC VD device that can vaporize these raw materials in the same vaporizer. In forming the Ru film 25, first, the temperature of the susceptor in the MOCVD chamber is set to 500 ° C., and then the semiconductor substrate 11 is mounted on the susceptor. Then, after the temperature of the semiconductor substrate 11 becomes constant, a Ru raw material is supplied into the MOCVD chamber together with a nitrogen gas as a carrier gas, as shown in FIG. By maintaining this state, the Ru film 25 is formed.

Next, the nitrogen gas is reduced to 20% by volume, the supply of oxygen gas for 80% by volume as a reaction gas is started, and the supply of Bi raw material is started. Immediately thereafter, the supply of the Ru raw material is stopped. As a result, as shown in FIG. 1, the amount of Bi in the MOCVD chamber increases and the amount of Ru decreases. During this time, the lower conductive compound month trillions (B i _₂ Ru ₂ 0 ₇ one _x film) 25 a is formed.

After the Ru source is no longer introduced into the MOCVD chamber, supply of the Ti source and La source is started while maintaining the supply of the Bi source, as shown in Fig. 1. By maintaining this state, the BLT film 26 is formed.

Next, as shown in FIG. 1, the supply of the Ti raw material and the La raw material is stopped, and immediately thereafter, the supply of the Bi raw material is also stopped.

Through these steps, Ru 25, lower conductive compound film 25a, and BLT film 26 are formed.

After the Bi raw material, the Ti raw material, and the La raw material are no longer completely introduced into the MOCVD chamber, the semiconductor substrate 11 is removed from the MOCVD chamber, and the PLT is deposited on the BLT film 26 as shown in FIG. 2B. A t film (upper electrode film) 27 is formed by sputtering, and annealing is performed for 60 minutes in an oxygen atmosphere at 500 ° C., for example. By this annealing, the plasma damage of the BLT film 26 due to the sputter deposition of the Pt film 27 is recovered. Subsequently, as shown in FIG. 2C, the Pt film 27 and the BLT film are formed by using patterning and etching techniques. 26, By processing the lower conductive compound film 25a and the Ru film 25, a stack structure in which the Pt film 27 is used as the upper electrode, the Ru film 25 is used as the lower electrode, and the BLT film 26 is sandwiched between them. Is formed. In this processing, for example, a laminated film (not shown) of a plasma TEOS (tetraethyl orthosilicate) film and a TiN film is used as a hard mask. The LT film 26, the lower conductive compound film 25a and the Ru film 25 are etched all at once.

Next, as shown in FIG. 2D, an alumina protective film 28 covering the ferroelectric capacitor is formed on the entire surface. The alumina protective film 28 is formed, for example, by the CVD method, and has a thickness of, for example, 5 to 20 nm, and 10 nm in the present embodiment.

Next, as shown in FIG. 2E, after an interlayer insulating film 29 is formed on the entire surface, it is planarized by CMP. As the interlayer insulation layer 29, for example, a silicon oxide film is formed using an HDP (High Density Plasma) CVD apparatus. Further, a TEOS oxide film may be formed as the interlayer insulating film 29. The remaining film thickness after the CMP is, for example, 300 nm on the Pt film 27.

Subsequently, as shown in FIG. 2F, using a patterning and etching technique, the high-concentration diffusion layer 1 shared by the two MOS transistors 14 is added to the interlayer insulating film 29 and the alumina protective film 28. Form a contact hole reaching W plug 24 connected to 6. Next, a glue film 30 is formed in this contact hole, for example, a 50-nm-thick TiN film, and then a W film is buried by, for example, a CVD method, and planarized by CMP (chemical mechanical polishing). Thus, a W plug 31 is formed. After that, the surface of the interlayer insulating film 29 and the surface of the W plug 31 are exposed to N ₂ plasma at 350 ° C., for example. The time of this plasma processing is, for example, 120 seconds.

Next, a W oxidation preventing film (not shown) is formed on the entire surface. As the W oxidation preventing film, for example, a SiON film can be used, and its thickness is, for example, about 10 程度 ηηι. Then, using a patterning and etching technique, as shown in FIG. 2G, a contact hole reaching the Pt film 27 serving as the upper electrode is formed in the W oxidation preventing film and the interlayer insulating film 29. I do. Subsequently, an anneal is applied to recover the damage caused by the etching. This Aniru, for example 5 5 0 ° C in may be a furnace Aniru 0 ₂ atmosphere, the time is for example for 60 minutes. After this annealing, the W oxidation preventing film is removed by etch back.

Next, a glue film, a wiring material film, and a glue film are sequentially deposited. As the lower glue film, for example, a laminated film of a 70 nm thick TiN film and a 5 nm Ti film may be formed. 100 nm A 1—Cu alloy film The upper glue film may be, for example, a laminated film of a 30 nm thick TiN film and a 6011111 thin film.

Next, an anti-reflection film is formed on the upper glue film by coating, and a resist is further applied. Subsequently, the resist film is processed so as to match the wiring pattern, and the antireflection film, the upper glue film, the wiring material film, and the lower glue film are etched using the processed resist film as a mask. For example, a SiON film can be used as the antireflection film, and its thickness is, for example, about 30 nm. By such etching, as shown in FIG. 2G, a glue film 32, a wiring 33 and a glue film 34 are formed.

Then, further, an interlayer insulating film is formed, a contact plug is formed, and wirings for the second and subsequent layers from the bottom are formed. Then, a cover film made of, for example, a TEOS oxide film and a SiN film is formed to complete a ferroelectric memory having a ferroelectric capacitor.

As described above, in the present embodiment, when the Ru film 25 as the lower electrode film and the BLT film 26 as the ferroelectric film are continuously formed in the same chamber, the order of starting and stopping the supply of the raw material is determined. The lower conductive compound film 25a is formed before the BLT film 26 is formed, and the reaction between Ru and Bi is completed in the lower conductive compound film 25a. . Therefore, when the BLT film 26 is formed, the diffusion of Ru into the BLT film 26 is prevented by the lower conductive compound film 25a. Therefore, according to the present embodiment, even if the Ru film 25 is used as the lower electrode, the leak current does not increase as before.

Here, the result of the inventors of the present invention verifying the manufacturing method according to the first embodiment will be described. In this verification, a SiO ₂ film and a Ti N film were formed on a Si substrate (wafer), and a ferroelectric capacitor was formed thereon. The conditions for forming the ferroelectric capacitor are the same as in the first embodiment. However, the thickness of the Ru film 25 was about 10 Onm, and the thickness of the BLT film 26 was about 100 nm.

Before forming the Pt film 27, the composition in the thickness direction of the stacked film including the BLT film 26 and the Ru film 25 was analyzed by SIMS. A region where Bi and Ru coexist is observed over a thickness of about 20 nm. Was. This region is the lower conductive compound film 25a. Also, no diffusion of 1 u into the BLT film 26 was observed.

Further, a Pt film 27 as an upper electrode film was formed by a sputtering method using a metal through mask, and after annealing for 60 minutes in an oxygen atmosphere at 500 ° C., a leakage current of 5 V was obtained. was measured density, the current density was O over da one ^{1 X 1 0- 6 a / cm} 2. Also, the 1.5 V switch charge amount Qsw indicating the polarization characteristic was about 30 μC / cm ² . As a result, according to the first embodiment, it was confirmed that a ferroelectric capacitor having good characteristics could be obtained.

(Second embodiment)

Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the method of manufacturing a strong dielectric capacitor. FIG. 4 is a timing chart showing a method for manufacturing a ferroelectric memory according to the second embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating a method of manufacturing a ferroelectric memory according to a second embodiment of the present invention, and FIG. 6 illustrates a ferroelectric capacitor manufactured according to the second embodiment. It is sectional drawing. FIG. 5 corresponds to FIG. 2B showing a part of the steps of the first embodiment.

In the present embodiment, first, the steps up to the formation of the W plug 24 are performed in the same manner as in the first embodiment.

Next, as shown in FIG. 5, an Ir film (lower electrode film) 35 is formed on the entire surface by sputtering.

Then, as shown in FIG. 5, BL TB 26, upper conductive compound B 37 a and RuO ₂ film 37 are continuously formed in the same chamber by the M〇C VD method. .

Here, a method of forming these films 26, 37a and 37 will be described. As these raw materials (precursors) and solvents, for example, those shown in Table 1 and n-hexane are used as in the first embodiment. As in the first embodiment, it is desirable to use an MOC VD apparatus capable of degassing these raw materials in the same vaporizer, as in the first embodiment.

In forming the BLT film 26, first, the temperature of the susceptor of the MOC VD chamber is set to 500 ° C., and the semiconductor substrate 11 is placed on the susceptor. And half MOCVD After the temperature of the conductor substrate 11 becomes constant, as shown in FIG. 4, the oxygen gas 80 vol ^_0/0 as nitrogen gas 20 vol ^_0/0 and the reaction gas as a carrier gas, a B i starting material Supply into the chamber. Immediately after that, supply of Ti raw material and La raw material is started. By maintaining this state, the BLT film 26 is formed. Next, the supply of the Ti raw material and the La raw material was stopped, and after the Ti raw material and the La raw material were not completely introduced into the MOCVD chamber, the supply of the Ru raw material was started as shown in FIG. Immediately thereafter, the supply of the Bi raw material is stopped. As a result, as shown in FIG. 4, the amount of Ru in the MOCVD champer increases and the amount of Bi decreases. During this time, the upper conductive tens raw compound film _{_{_{(B i 2 Ru 2 0 7}}} _ x film) 37 a is formed. After the B i material could be introduced completely MOCVD chamber also, as shown in FIG. 4, by continuing the supply of the Ru material, 11_Rei ₂ film 37 is made form. The reason why the RuO ₂ film 37 is formed instead of the Ru film is that the supply of oxygen gas is maintained in the present embodiment, unlike the case of forming the Ru film 25 in the first embodiment. .

Then, as shown in FIG. 4, the supply of the Ru raw material is stopped.

Through these steps, the BLT film 26, the upper conductive compound film 37a and the RuO ₂ film 37 are formed.

Then, after the Ru raw material is not completely introduced into the MOCVD chamber, the semiconductor substrate 11 is taken out of the MOCVD chamber, and the processes after the ferroelectric capacitor are processed as in the first embodiment. Complete a ferroelectric memory having a ferroelectric capacitor.

In the present embodiment, before the RuO ₂ film 37 serving as the upper electrode film is formed, the upper conductive compound film 37a is formed, and the reaction between Ru and Bi in the upper conductive compound film 37a is performed. Has been completed. Therefore, when forming the RuO ₂ film 37, the diffusion of Ru into the BLT film 26 is prevented by the upper conductive compound film 37a. Therefore, according to the present embodiment, even if the RuO ₂ film 37 is used as the upper electrode, the leak current does not increase as before.

Here, the results of verification of the manufacturing method according to the second embodiment by the present inventor will be described. In this verification, as in the first embodiment, on the Si substrate (wafer) Then, a SiO ₂ film and a Ti N film were formed, and a ferroelectric capacitor was formed thereon. The conditions for forming the ferroelectric capacitor are the same as in the second embodiment. However, the thickness of the BLT film 26 was about 100 nm, and the thickness of the Ru ₂ film 37 was about 100 nm.

Then, after forming the Ru_〇 ₂ film 37, composition of the film thickness direction of the laminated film including a Ru_〇 ₂ film 37 and BLT film 26 was analyzed by S IMS, R u O ₂ film 37 and the B LT film 26 In between, a region where Bi and Ru coexist was observed over a thickness of about 20 nm. This region is the upper conductive compound film 37a. Further, diffusion of Ru into the BLT film 26 was not observed.

Further, by photolithography, patterning the thick portions of 1 20 nm, which corresponds to Ru0 ₂ layer 37 and the upper conductive compound film 37 a, after the Aniru for 60 minutes in an oxygen atmosphere at 500 ° C When the leakage current density of 5 V was measured, the current density was on the order of 1 × 10 ¹⁶ AZcm ² . Further, the 1.5 V switch charge amount Qsw indicating the polarization characteristic was about 30 μCZcm ² . As a result, according to the second embodiment, it was confirmed that a ferroelectric capacitor having good characteristics could be obtained.

(Third embodiment)

Next, a third embodiment of the present invention will be described. The third embodiment differs from the first and second embodiments in the method of manufacturing a strong dielectric capacitor. FIG. 1 is a timing chart showing a method for manufacturing a ferroelectric memory according to a third embodiment of the present invention. FIG. 8 is a cross-sectional view illustrating a method of manufacturing a ferroelectric memory according to the third embodiment of the present invention, and FIG. 9 illustrates a ferroelectric capacitor manufactured according to the third embodiment. It is sectional drawing. FIG. 8 corresponds to FIG. 2B showing some steps of the first embodiment.

Next, as shown in FIG. 8, Ru film (lower electrode film) 25, lower conductive film 25a, BLT film 26, upper conductive compound film 37a, and RuO ₂ film (upper surface) are formed on the entire surface. Electrode films) 37 are continuously formed by MOCVD in the same chamber. Here, a method for forming these films 25, 25a, 26, 37a and 37 will be described. As these raw materials (precursors) and solvents, for example, those shown in Table 1 and n-hexane are used as in the first embodiment. As in the first embodiment, it is desirable to use a MOCVD apparatus capable of vaporizing these raw materials in the same vaporizer, as in the first embodiment.

In forming the Ru film 25, as in the first embodiment, first, the temperature of the susceptor in the MOCVD chamber is set to 500 ° C., and then the semiconductor substrate 11 is mounted on the susceptor. Then, after the temperature of the semiconductor substrate 11 becomes constant, a Ru raw material is supplied into the MOCVD chamber together with a nitrogen gas as a carrier gas as shown in FIG. By maintaining this state, the Ru film 25 is formed.

Next, the nitrogen gas is reduced to 20% by volume, the supply of oxygen gas of 80% by volume as a reaction gas is started, and the supply of Bi raw material is started. Immediately thereafter, the supply of the Ru raw material is stopped. As a result, as shown in FIG. 7, the amount of Bi in the MOCVD champer increases and the amount of Ru decreases. During this time, the lower conductive compound film _{_{_{(B i 2 Ru 2 0 7}}} - x film) 25 a is formed.

After the Ru source is no longer completely introduced into the MOCVD champer, as shown in Fig. 7, the supply of the Ti source and the La source is started while the supply of the Bi source is maintained. By maintaining this state, the BLT film 26 is formed.

Next, the supply of the Ti raw material and the La raw material was stopped, and after the Ti raw material and the La raw material were not completely introduced into the MOCVD chamber, the supply of the Ru raw material was started as shown in FIG. Immediately thereafter, the supply of the Bi raw material is stopped. As a result, as shown in FIG. 7, the Ru amount in the MOCVD chamber increases and the Bi amount decreases. During this time, the upper conductive compound film _{_{_{(B i 2 Ru 2 0 7}}} x film) 37 a is formed. After the B i material could be introduced completely MOCVD chamber also, as shown in FIG. 7, by continuing the supply of the Ru material, length 10 ₂ film 37 is made form.

Thereafter, as shown in FIG. 7, the supply of the Ru raw material is stopped.

Through these steps, a 111 film 25, a lower conductive compound film 25a, a BLT film 26, an upper conductive compound film 37a and a RuO ₂ film 37 are formed. Then, after the Ru raw material is not completely introduced into the MOCVD chamber, the semiconductor substrate 11 is taken out of the MOCVD chamber, and the processes after the ferroelectric capacitor are processed as in the first embodiment. Complete a ferroelectric memory having a ferroelectric capacitor.

In the present embodiment, before forming the BLT film 26, the lower conductive compound film 25a is formed, and the reaction between Ru and Bi is completed in the lower conductive compound film 25a. ing. Further, before forming the Ru〇 ₂ film 37 serving as the upper electrode film, an upper conductive compound Moon 37a is formed, and the reaction with Ru and Bi in the upper conductive compound film 37a is performed. Has been completed. Therefore, when the BLT film 26 is formed, the diffusion of Ru from the Ru film 25 into the BLT film 26 is prevented by the lower conductive film 25 a, and the Ru ₂ film 37 is formed. At the time of formation, diffusion of Ru from the 11 膜₂ film 37 into the BLT film 26 is prevented by the upper conductive compound film 37a. Therefore, according to the present embodiment, even if the Ru film 25 is used as the lower electrode and the RuOj 37 is used as the upper electrode, the leak current does not increase as in the related art. Here, a description will be given of the result of the inventors of the present application verifying the manufacturing method according to the third embodiment. In this verification, a SiO ₂ film and a Ti N film were formed on a Si substrate (wafer), and a ferroelectric capacitor was formed thereon. The conditions for forming the ferroelectric capacitor are the same as in the third embodiment. However, the thickness of 1¾ 11 film 25 is 100 ₁ 1111 extent, the thickness of the BLT layer 26 is about 100 nm, the thickness of the Ru_〇 ₂ film 37 was set to about 1 00 nm.

Then, after forming the Ru0 ₂ layer 37, composition of the film thickness direction of the laminated film including a scale 11_Rei ₂ film 37, 81 ^ Chomaku 26 and R u film 25 was analyzed by S IMS, R u O ₂ Between the film 37 and the BLT film 26 and between the BLT film 26 and the Ru film 25, regions where Bi and Ru coexist over a thickness of about 20 nm were observed. This region is the upper conductive compound film 37a and the lower conductive compound film 25a, respectively. In addition, diffusion of Ru into the BLT film 26 was not observed.

Furthermore, by using photolithography technology, a portion with a thickness of 120 nm corresponding to the RuOj 37 and the upper conductive compound film 37a was patterned, and an annealing was performed for 60 minutes in an oxygen atmosphere at 500 ° C. Later, 5 V leakage current density was measured However, the current density was on the order of 1 × 10 ¹⁶ A / cm ² . Moreover, 1. 5 V switches amounts Q sw of showing a polarization characteristic was 30 C / cni ² about. As a result, according to the second embodiment, it was confirmed that a ferroelectric capacitor having good characteristics could be obtained.

In the third embodiment, as shown in FIG. 7, immediately after the supply of the Bi raw material is started, the supply of the Ru raw material is stopped. However, as shown in FIG. The supply of the Ru raw material may be stopped after the supply amount of Ru reaches a steady state. Further, as shown in FIG. 7, immediately after the supply of the Ru raw material was started, the supply of the Bi raw material was stopped, but as shown in FIG. 10, the supply amount of the Ru raw material reached a steady state. After that, the supply of the Bi raw material may be stopped. These are the same in the first and second embodiments. In any embodiment, 1 11 use Ite 1 110 ₂ film generations Wari membrane may be used Ru film instead of Ru_〇 ₂ film. Further, the material of the electrode film is not particularly limited.

Further, the ferroelectric film of B i layered system is not limited to the B LT film, for example, instead of BLT _{film, SBT (S r B i 2} T a 2 0 7) film, SBN (S r B i _₂ Nb ₂ O _g) film or a _{_{BIT (B i 4 T i 3}} 0 12) may be formed film. When these films are formed, instead of the La raw material and the Ti raw material in forming the BLT film, for example, an Sr raw material and a Ta raw material may be supplied, or three raw materials and three raw materials may be used. 1) The power to supply the raw materials or only the Ti raw materials may be supplied.

Next, a MOCVD apparatus suitable for implementing the present invention will be described. In the conventional MOC VD apparatus, a vaporizer is provided for each raw material, and raw gas is supplied from these vaporizers to a mixer via each pipe, and after each raw material gas is mixed in the mixer, Some are supplied from the shower head into the chamber. On the other hand, recently, a MOCVD apparatus in which a plurality of raw materials are degassed in one vaporizer to generate a raw material gas, and these powers are mixed and supplied from a shower head into a chamber. It has been developed.

In the conventional MOC VD device, a long pipe is required from when the gas is vaporized in the vaporizer to when it is supplied into the chamber. Before feed gas is supplied into the chamber, And the like may generate particles inside. In contrast, the recently developed MOC VD device suppresses the generation of such particles.

In particular, in the present invention, there are many steps of simultaneously supplying a plurality of source gases into the chamber, and it is necessary to appropriately switch on / off of the supply of these gases, so that a recently developed MOC VD apparatus is used. The effect of suppressing generation of particles is remarkable. In addition, the recently developed MOC VD device requires only one vaporizer, so when using many types of raw gas, the cost can be reduced by reducing the number of vaporizers. In using such a vaporizer, a Bi layered system such as a Bi raw material (organic compound of Bi), a La raw material (organic compound of La), and a Ti raw material (organic compound of Ti) is used. It is desirable to use a ferroelectric film raw material supply system connected to a Ru raw material (organic compound of a metal element) supply system.

In any of the embodiments, the temperature of the shower head and the temperature of the substrate are changed from the start of gas supply into the MOC VD chamber to the end of film formation in the MOC VD chamber. Is preferably kept constant. By keeping these constant, it becomes possible to form each film more stably. Industrial applicability

As described in detail above, according to the present invention, the formation of the electrode film and the formation of the ferroelectric film can be performed continuously in one chamber. For this reason, the manufacturing time can be reduced, and the cost of the manufacturing equipment can be reduced. Further, since the number of times of wafer transfer is reduced, contamination that may occur during transfer is suppressed, and high reliability can be obtained. Further, by forming the conductive compound film, a leak current in the ferroelectric film can be significantly reduced. Ru raw material Ru (EtCp), (Ru (C ₅ H ₄ C ₂ H ₅ ) ₂ : Bis-ethyl-cyclo.

Bi raw material Bi (Ph) ₃ (Bi (C ₆ H ₅ ) ₃ : trifenyl-bismuth)

L a raw material _{La (dibm) 3 (La (} C 8 H 15 0 2) 3:! Door) S - Shea ,, isophthalic Rirumetana - door - lantern)

Ti raw material Ti (0iPr) ₄ (Ti [0CH (CH ₃ ) ₂ ] ₄ : tetra-isofuran oxy-titanium)

Claims

The scope of the claims

1. The method for manufacturing a ferroelectric capacitor with a Bi (bismuth) layered ferroelectric film is as follows.

A step of introducing a gas containing a first metal element into the C VD champer to form a lower electrode film containing the first metal element;

While continuously introducing the gas containing the first metal element into the CVD chamber, a gas containing Bi (bismuth) and O (oxygen) is further introduced, and the gas on the lower electrode film is formed on the lower electrode film. Forming a first conductive compound film containing a first metal element and Bi (bismuth);

Stopping the introduction of the first metal element into the CVD chamber; and continuously introducing a gas containing Bi (bismuth) and O (oxygen) into the CVD chamber. (Bismuth) A gas containing a metal element for a ferroelectric film other than Bi (bismuth) among the metal elements constituting the layered ferroelectric film is introduced into the first conductive compound film. Forming the B i (bismuth) layered ferroelectric film in

Stopping the introduction of Bi (bismuth) and the metal element for the ferroelectric film into the CVD chamber;

Forming an upper electrode film on the Bi (bismuth) layered ferroelectric film.

2. The method of manufacturing a ferroelectric capacitor with a Bi (bismuth) layered ferroelectric film is as follows.

Forming a lower electrode film;

In the CVD chamber, B i (bismuth), a metal element for a ferroelectric film excluding B i (bismuth) among the metal elements constituting the layered ferroelectric film, and O ( Introducing a gas containing oxygen) to form the Bi (bismuth) layered ferroelectric film on the lower electrode film;

Stopping the introduction of the metal element for the ferroelectric film into the CVD chamber; A gas containing a second metal element is introduced into the CVD chamber while a gas containing Bi (bismuth) and O (oxygen) is continuously introduced into the CVD chamber. Forming a second conductive compound film containing the second metal element and Bi (bismuth) on the ferroelectric film;

Stopping the introduction of Bi (bismuth) into the CVD chamber; and continuously introducing a gas containing the second metal element into the CVD chamber; Forming an upper electrode film containing the second metal element on the film;

Having.

3. The method for manufacturing a ferroelectric capacitor according to claim 1,

The step of stopping the introduction of Bi (bismuth) and the metal element for the ferroelectric film into the CVD champer includes:

A step of stopping the introduction of the metal element for the ferroelectric film into the CVD chamber, and a step of continuously introducing a gas containing Bi (bismuth) and O (oxygen) into the CVD chamber. A gas containing the second metal element is introduced to form a second conductive compound film containing the second metal element and Bi (bismuth) on the Bi (bismuth) layered ferroelectric film. Forming,

Stopping the introduction of Bi (bismuth) into the CVD champer;

The step of forming the upper electrode film,

Forming a top electrode film containing the second metal element on the second conductive compound film by continuously introducing a gas containing the second metal element into the CVD chamber; Have.

4. The method for manufacturing a ferroelectric capacitor according to claim 1,

The first metal element is Ru (ruthenium).

5. The method for manufacturing a ferroelectric capacitor according to claim 2,

The second metal element is Ru (ruthenium).

6. The method for producing a ferroelectric capacitor according to claim 1! The step of stopping the introduction of the first metal element into the CVD chamber is performed after a supply amount of a gas containing Bi (bismuth) and O (oxygen) reaches a steady state.

7. In the method of manufacturing a ferroelectric capacitor according to claim 1,

The step of stopping the introduction of the first metal element into the CVD chamber is performed before the supply amount of the gas containing Bi (bismuth) and O (oxygen) reaches a steady state.

8. The method for manufacturing a ferroelectric capacitor according to claim 2!

The step of stopping the introduction of Bi (bismuth) into the CVD chamber is performed after the supply amount of the gas containing the second metal element reaches a steady state.

9. The method for manufacturing a ferroelectric capacitor according to claim 2,

The step of stopping the introduction of Bi (bismuth) into the CVD chamber is performed before the supply amount of the gas containing the second metal element reaches a steady state.

10. The method of manufacturing a ferroelectric capacitor according to claim 4,

The lower electrode film, R u (ruthenium) layer or R U_〇 ₂ (oxide ruthenium) is a membrane.

11. The method for manufacturing a ferroelectric capacitor according to claim 5.

The upper electrode film, R u (ruthenium) layer or R U_〇 ₂ (ruthenium oxide) is a membrane.

12. The method of manufacturing a ferroelectric capacitor according to claim 4,

The lower conductive film is composed of Ru (ruthenium), Bi (bismuth) and O (oxygen). '

13. The method for producing a ferroelectric capacitor according to claim 5,

The upper conductive compound film is composed of Ru (ruthenium), Bi (bismuth), and O (oxygen).

14. The method for manufacturing a ferroelectric capacitor according to claim 1, wherein

The organic compound of Bi (bismuth), the metal element for the ferroelectric film, and the organic compound of the metal element are vaporized using the same vaporizer.

15. The method for manufacturing a ferroelectric capacitor according to claim 2, wherein The organic compound of Bi (bismuth), the metal element for the ferroelectric film, and the organic compound of the metal element are vaporized using the same vaporizer.

16. A method for manufacturing a ferroelectric capacitor according to claim 14, wherein

A supply means for supplying an organic compound of Bi (bismuth) and the metal element for the ferroelectric film, and a supply means for supplying the organic compound of the metal element are connected to the vaporizer.

17. The method for manufacturing a ferroelectric capacitor according to claim 15, wherein

18. The method for manufacturing a ferroelectric capacitor according to claim 1, wherein

The temperature of the shower head and the substrate temperature in the CVD chamber are kept constant from the start of gas supply into the CVD chamber to the end of film formation in the CVD chamber. Keep in ₀

1 9. The method for manufacturing a ferroelectric capacitor according to claim 2! /,hand,

From the start of gas supply into the CVD chamber to the end of film formation in the CVD chamber, the temperature of the showerhead and the substrate in the CVD chamber are kept constant. To hold.