JP4111963B2 - Capacitor manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a capacitor used for, for example, charge storage of a memory cell in a DRAM (Dynamic Random Access Memory).

As a stacked capacitor, there is one in which a capacitive insulating film is made of tantalum oxide (Ta ₂ O ₅ ) having a high dielectric constant and a withstand voltage. Amorphous silicon is formed on the inner wall of the opening of the interlayer insulating film, and is polycrystallized and conductive by heat treatment to form a lower electrode. A silicon nitride film (SiN) is formed on the surface of the lower electrode of polysilicon, a capacitive insulating film of tantalum oxide, and an upper electrode of a titanium nitride film (TiN).

Here, in order to increase the effective electrode surface area and increase the capacitance, HSG (Hemi Spherical Grain) nuclei composed of hemispherical crystal grains are formed on the surface of amorphous silicon. That is, the oxide film on the surface of the amorphous silicon that becomes the base of the lower electrode is removed to form a surface uneven portion. An amorphous silicon film is further deposited on the surface irregularities by chemical vapor deposition (CVD), and this is used as the lower electrode. Next, the oxide film is removed by washing with a chemical solution to form HSG (Hemi Spherical Grain) nuclei composed of hemispherical crystal grains, and heat treatment is performed to form HSG-Si. Then, the silicon nitride film, the tantalum oxide capacitive insulating film, and the upper electrode of the titanium nitride film are formed thereon.
Japanese Patent Application Laid-Open No. 2002-124650 (page 5-7, FIG. 3-10)

By the way, tantalum oxide The capacitor has the following problems. Since the electric field is locally concentrated at the protrusions of particles or HSG-Si grain boundaries (crystal grain boundaries) generated during the formation of HSG-Si, TDDB (Time Dependent Dielectric Breakdown) characteristics deteriorate. In addition, since the tantalum oxide film has a small potential barrier, a large leakage current is generated.

In addition, reducing gas such as hydrogen sintering (heat treatment) or film formation using NH ₃ gas may be used in the lower electrode formation to wiring process, etc., but the tantalum oxide film is reduced to metal tantalum by the reducing gas, The TDDB characteristic is deteriorated.

  Also, in the wiring process after the formation of the upper electrode, plasma treatment may be performed to form an interlayer insulating film and an adhesion layer at the contact. However, the tantalum oxide film is damaged by the plasma treatment, and the TDDB characteristic is reduced. to degrade.

  The present invention has been made in view of such circumstances, and provides a capacitor using a metal oxide film having a high dielectric constant, a high capacity, a small leakage current, and a low TDDB characteristic, and a method for manufacturing the same. With the goal.

According to another aspect of the present invention, there is provided a first capacitor manufacturing method comprising: forming an opening in an interlayer insulating film on a semiconductor substrate; and forming a lower electrode made of polycrystalline silicon having an uneven surface on the inner wall of the opening. Forming a chemical oxide film by oxidizing the surface of the lower electrode having the surface irregularities, and then nitriding the surface of the surface irregularities of the lower electrode via the chemical oxide film , forming a step of modifying the chemical oxide film on the silicon oxynitride film, then forming a capacitor insulating film made of a metal oxide film on the silicon oxynitride film, an upper electrode on the capacitive insulating film The process to perform is included.

  According to the above configuration, the chemical oxide film is formed on the surface of the surface uneven portion of the lower electrode before the silicon oxynitride film is formed. As a result, the chemical oxide film rounds the boundary protrusions of the particle protrusions or the surface irregularities, thereby suppressing the occurrence of electric field concentration in the protrusions. As a result, it is possible to suppress an increase in leakage current due to the protrusion and deterioration of the TDDB characteristics.

  The step of forming the chemical oxide film can be realized by cleaning the surface uneven portion of the lower electrode to expose the silicon clean surface of the surface uneven portion, and subsequently performing a wet treatment with a chemical solution having oxidizing power. . Thereby, the rounding by oxidation with respect to the boundary protrusion of a particle protrusion or a surface uneven | corrugated | grooved part improves the efficiency.

  In the second capacitor manufacturing method according to the present invention, in the first capacitor manufacturing method, the step of forming the upper electrode includes forming a titanium nitride film as the upper electrode at a deposition temperature of 650 ° C. to 700 ° C. To do.

According to the above configuration, by forming the TiN film as the upper electrode on the capacitive insulating film at 650 ° C. to 700 ° C., one of the source gases for forming TiN as compared with 550 ° C. to 650 ° C., which is a relatively low temperature. NH ₃ is suppressed from being taken into the TiN film is. Therefore, the reduction of the metal oxide film that is a capacitive insulating film is suppressed, and the life of the TDDB characteristic is further improved. If the film forming temperature is less than 650 ° C., the remaining NH ₃ having a reducing action in the film becomes excessive. On the other hand, when the temperature is higher than 700 ° C., dopant re-diffusion occurs, and the device profile is adversely affected by changing the impurity profile.

In the method for manufacturing a capacitor, the step of forming the chemical oxide film preferably oxidizes the surface of the lower electrode by immersing in a chemical solution having oxidizing power such as hydrogen peroxide water, ozone water, or nitric acid water. . The oxidizing power is in the order of nitric acid> ozone water> hydrogen peroxide water. By using these properly according to conditions, the throughput is improved and the production capacity is improved.

  In the above-described capacitor manufacturing method, the step of forming the upper electrode is preferably performed after the capacitor insulating film is heat-treated in an oxygen atmosphere. By supplying oxygen, the density of defects in the capacitor insulating film is reduced.

  In addition, according to the first method for manufacturing a capacitor of the present invention, the silicon clean surface of the surface uneven portion of the lower electrode is exposed before the silicon oxynitride film is formed, and then wet treatment is performed with a chemical solution having an oxidizing action. Then, a chemical oxide film is formed on the surface of the surface irregularities. As a result, the chemical oxide film has the effect of rounding the particle protrusions on the surface of the lower electrode or the boundary protrusions of the surface irregularities. That is, in a capacitor using a metal oxide film having a high dielectric constant, it is possible to suppress an increase in leakage current and deterioration of TDDB characteristics due to generation of a particle protrusion or a boundary protrusion of a surface uneven portion.

According to the second method for manufacturing a capacitor of the present invention, in addition to the above-described effects, a TiN film as an upper electrode is formed on the capacitor insulating film at 650 ° C. to 700 ° C. Thereby, since NH ₃ which is a raw material gas for forming TiN can be prevented from being taken into the TiN film, there is an effect of suppressing reduction of the metal oxide film which is a capacitive insulating film. That is, in the capacitor using the metal oxide film having a high dielectric constant, the life of the TDDB characteristic can be further improved.

(Subsidiary explanation)
Before describing the embodiment of the present invention, a comparative example that is the basis of the embodiment will be described first in order to facilitate understanding.

Regarding a stacked capacitor using a tantalum oxide (Ta ₂ O ₅ ) film having a high dielectric constant and withstand voltage as a capacitor insulating film, FIG. 15, FIG. 16 will be described. A capacitor diffusion layer 12 is formed on the surface of the silicon substrate 11, and an interlayer insulating film 13 is formed of a silicon oxide film on the entire surface. A contact hole 14 is formed in the interlayer insulating film 13 and filled with amorphous silicon to form a lower electrode 15. Further, an interlayer insulating film 13a is formed, and an opening 14a is formed. The lower electrode 15a is formed on the inner wall of the opening 14a, the surface oxide film is removed after patterning, and the surface uneven portion 16 is formed. An amorphous silicon film (a-Si film) is deposited on the surface irregularities 16 by low pressure chemical vapor deposition (LPCVD). Then, the a-Si film is finely processed and the lower electrode is patterned. Next, it is cleaned with a chemical solution, and the oxide film on the surface of the a-Si film is removed. Inserted into a high vacuum reactor, HSG (Hemi Spherical Grain) nuclei composed of hemispherical crystal grains are formed on the surface of the a-Si film, and heat treatment is performed to form HSG-Si.

The a-Si film is polycrystallized by the heat treatment. Next, by performing PH3 annealing, the polycrystallized Si is made conductive to form the lower electrode 15a. Then, heat treatment is performed in an atmosphere of ammonia (NH ₃ ) gas to nitride the surface of the lower electrode 15a of the polysilicon film, thereby forming the SiN film 17. Further, after forming SiO ₂ , SiON, Ta ₂ O ₅ or the like to be the capacitive insulating film 18, an upper electrode 19 made of a TiN film is formed by CVD using TiCl ₄ and NH ₃ as raw materials to complete the capacitor.

This Ta ₂ O ₅ capacitor and its manufacturing method have the following problems.

  Due to the particles generated during HSG-Si formation or the grain boundary (crystal grain boundary) of HSG-Si, the electric field is locally concentrated on the protrusions of the particles and HSG-Si grain boundary, and TDDB (Time Dependent Dielectric) Breakdown characteristics are degraded. In addition, since the potential barrier becomes small, a large leakage current is generated.

In some cases, a reducing gas such as hydrogen sintering (heat treatment) or film formation using NH ₃ gas is used in the lower electrode formation to wiring process, etc., but the Ta ₂ O ₅ film is reduced by the reducing gas, and TDDB. Characteristics deteriorate.

Further, in the wiring process after the formation of the upper electrode 19, plasma treatment may be performed for forming an interlayer insulating film and an adhesion layer at the contact. However, the Ta ₂ O ₅ film is damaged by the plasma treatment, The TDDB characteristic is deteriorated.

  In order to eliminate the inconvenience in this comparative example, the following devices are devised in the embodiment of the present invention.

(Description of Embodiment)
Embodiments of a capacitor and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
The manufacturing method of the capacitor according to the first embodiment of the present invention is shown in FIG. 1 and FIG. 2-FIG. 9 will be used for explanation.

  In the first step, an interlayer insulating film 3a is formed along with the formation of the cell region by dry etching (see FIG. 2).

  In the second step, amorphous silicon for the lower electrode 5a is deposited in the opening 4a of the interlayer insulating film 3a (see FIG. 3).

  In the third step, the oxide film on the amorphous silicon surface is removed by wet cleaning.

  In the fourth step, the surface irregularities 6 of HSG-Si are formed on the amorphous silicon surface (see FIG. 4).

  In the fifth step, the lower electrode 5a made of amorphous silicon is patterned (see FIG. 5).

  In the sixth step, a chemical oxide film 7 is formed on the surface of amorphous silicon HSG-Si (see FIG. 6). The main points are enlarged (FIG. 7 to FIG. 9 are the same).

  In the seventh step, the chemical oxide film 7 is modified by nitriding to form a silicon oxynitride film 8 (see FIG. 7).

  In the eighth step, a capacitive insulating film 9 is formed on the silicon oxynitride film 8 (see FIG. 8).

  In the ninth step, RTA (Rapid Thermal Anneal) or RTO (Rapid Thermal Oxidation) is performed.

  In the tenth step, the upper electrode 10 is formed (see FIG. 9).

  Hereinafter, each of the above steps will be described sequentially.

  (1) FIG. As shown in FIG. 2, a capacitor diffusion layer 2 is formed on the surface of the silicon substrate 1. Then, an interlayer insulating film 3 is formed on the entire surface. The interlayer insulating film 3 is composed of a silicon oxide film or a BPSG film (a silicon oxide film containing boron glass and phosphorus glass). A contact hole 4 reaching the surface of the capacitor diffusion layer 2 is formed in the interlayer insulating film 3, the contact hole 4 is filled with amorphous silicon, and a lower electrode 5 connected to the capacitor diffusion layer 2 is formed. Next, an interlayer insulating film 3a is further formed on the lower electrode 5, and dry etching (D / E) is performed to form a memory cell region, thereby forming an opening 4a in the interlayer insulating film 3a.

(2) Next, FIG. As shown in FIG. 3, an a (amorphous) -Si film 5a (having a film thickness of 25 to 50 nm) is deposited by a low pressure CVD (Chemical Vapor Deposition) method using SiH ₄ or Si ₂ H ₆ as a reaction gas. Here, the film forming temperature is set in a range of 500 ° C. to 550 ° C.

  (3) Then, FIG. As shown in FIG. 4, the semiconductor substrate is immersed in dilute hydrofluoric acid that is a mixed chemical solution of hydrofluoric acid and pure water, and the natural oxide film and the like on the surface of the a-Si film are removed (oxide film removal). Here, the fluorine concentration in dilute hydrofluoric acid was 0.50 vol. %.

(4) Subsequently, a semiconductor substrate is inserted into a high-vacuum reactor in the process chamber, and heat treatment (pressure is about 1 × 10 ⁻⁵ Pa, temperature is about 600 ° C. to 650 ° C., SiH ₄ flow rate is 50 sccm) Apply. As a result, HSG nuclei are formed on the surface of the a-Si film, and HSG-Si which is hemispherical crystal grains is further formed. The a-Si film is polycrystallized by this heat treatment. Next, the polycrystalline Si film having the surface irregularities 6 is made conductive by performing PH3 annealing to form a lower electrode 5a. In this way, the lower electrode 5a of the capacitor made of polycrystalline silicon having the surface irregularities 6 on the surface is formed.

  (5) Next, FIG. As shown in FIG. 5, the lower electrode 5a is finely processed and patterned by a photolithography technique and a dry etching technique.

  (6) Next, FIG. As shown in FIG. 6, it is immersed in dilute hydrofluoric acid, which is a mixed chemical solution of hydrofluoric acid and pure water, and the surface of the surface irregularities 6 of HSG-Si is removed (oxide film removal). Then, a chemical oxide film 7 having a thickness of 0.5 to 1.5 nm in terms of a silicon oxide film is formed on the HSG-Si surface by dipping in a chemical solution having an oxidizing action such as hydrogen peroxide water, ozone water, or nitric acid water. .

Here, if the film thickness of the chemical oxide film 7 is less than 0.5 nm, it is difficult to control the film thickness. On the other hand, if the thickness of the chemical oxide film 7 is larger than 2.0 nm, the capacitor has a series structure of an SiO ₂ film and a metal oxide film, and the capacity reduction becomes remarkable. Therefore, the thickness of the chemical oxide film 7 is preferably 0.5 to 1.5 nm.

  In addition, since said chemical | medical solution has high oxidizability in order of nitric acid water> ozone water> hydrogen peroxide water, a throughput can be improved by selecting the chemical | medical solution with oxidizing power, and it can improve production capacity.

  (7) Next, FIG. As shown in FIG. 7, plasma treatment is performed in a nitrogen atmosphere at a pressure of 30 Pa, an RF power of 250 W, and a wafer stage temperature of 400 ° C. Thereby, the HSG-Si surface is nitrided through the chemical oxide film 7, and the chemical oxide film 7 is modified into a silicon oxynitride film 8 having a film thickness of 1.0 to 3.5 nm.

(8) Next, FIG. As shown in FIG. 8, a Ta ₂ O ₅ capacitive insulating film 9 is formed to 8 to 12 nm on the silicon oxynitride film 8 by CVD. As formation conditions, the pressure is about 30 Pa, the temperature is about 450 ° C. to 500 ° C., the source gas pentaethoxytantalum (Ta (OC ₂ H ₅ ) ₅ ) is about 0.1 cc, and the O ₂ gas is about 500 sccm. .

(9) After that, heat treatment of RTA (instantaneous thermal annealing) at 800 ° C. for about 90 seconds is performed in an oxygen atmosphere in order to densify the Ta ₂ O ₅ film and reduce the defect density by supplying oxygen.

(10) Finally, FIG. As shown in FIG. 9, a TiN film to be the upper electrode 10 is formed by a CVD method using TiCl ₄ (17.5 sccm) and NH ₃ (400 sccm) as raw materials at a pressure of 40 Pa and a film formation temperature of 550 ° C. to 650 ° C. Further, a resist pattern (not shown) serving as a mask for patterning the upper electrode 10 is formed thereon. Using this resist pattern as a mask, unnecessary portions of the TiN film are etched to form the upper electrode 10 made of the TiN film, thereby completing the production of the Ta ₂ O ₅ capacitor.

  The capacitor and the manufacturing method thereof according to the present embodiment described above have the following advantages.

Prior to the formation of the capacitive insulating film 9 made of a Ta ₂ O ₅ film (metal oxide film), the chemical oxide film 7 is formed by wet treatment of HSG-Si of the conductive lower electrode 5a. Thereby, the particle | grain protrusion which generate | occur | produced on HSG-Si of the lower electrode 5a, or a HSG-Si grain boundary protrusion can be rounded off. As a result, it is possible to suppress the occurrence of electric field concentration in the protrusion, and to reduce the leakage current and extend the life of the TDDB characteristic.

Further, by forming the chemical oxide film 7 on the surface of the conductive HSG-Si, a potential barrier superior to that of the Ta ₂ O ₅ film is formed, thereby reducing the leakage current and extending the life of the TDDB characteristics. be able to.

  According to the present embodiment, a capacitor with a small leakage current and a sufficiently long TDDB characteristic life can be manufactured with a relatively low thermal budget of 800 ° C. and 90 sec at the maximum. .

(Embodiment 2)
Next, a method for manufacturing the capacitor according to the second embodiment of the present invention will be described. This embodiment is shown in FIG. In step 9, the deposition temperature of the TiN film that becomes the upper electrode 10 is made higher than that in the first embodiment (550 ° C. to 650 ° C.) (about 50 ° C. to 100 ° C. higher).

In the same manner as in the first embodiment, FIG. 2 to FIG. Step 8 is executed. Then, FIG. As shown in FIG. 9, a TiN film to be the upper electrode 10 is formed by a CVD method using TiCl ₄ (17.5 sccm) and NH ₃ (400 sccm) as raw materials at a pressure of 40 Pa and a film forming temperature of 650 ° C. to 700 ° C. The deposition temperature of this TiN film is higher by about 50 ° C. to 100 ° C. than 550 ° C. to 650 ° C. in the first embodiment. This is because NH ₃ has a reducing action but reduces the residual concentration of NH _{3 in} the TiN film and suppresses the deterioration of the TDDB characteristics.

In the formation of a TiN film having a film formation temperature of less than 650 ° C. (for example, 630 ° C.), the residual concentration of NH _{3 in} the TiN film becomes excessive as compared with 650 ° C. or more (for example, 680 ° C.). On the other hand, when the temperature is higher than 700 ° C., it is considered that dopant re-diffusion occurs and the impurity profile is changed to influence the device characteristics. Therefore, the deposition temperature of the TiN film is set to 650 ° C. to 700 ° C.

Thereafter, a resist pattern (not shown) serving as a mask for patterning the upper electrode 10 is formed thereon. Using this resist pattern as a mask, unnecessary portions of the TiN film are etched to form the upper electrode 10 made of the TiN film, thereby completing the production of the Ta ₂ O ₅ capacitor.

As described above, in the capacitor manufacturing method of the present embodiment, in addition to the advantages of the first embodiment, by increasing the deposition temperature of the TiN film, the residual concentration of NH _{3 in} the TiN film is reduced. Since the reducing action of the Ta ₂ O ₅ film is suppressed, it has a function of suppressing the deterioration of the TDDB characteristics.

(Measurement results of the embodiment)
Next, FIG. 10-FIG. The measurement result of the present embodiment will be described with reference to FIG.

  FIG. 10 is the same as that shown in FIG. 6 is a TDDB characteristic graph according to the presence or absence of a chemical oxide film formation process of No. 6. The measurement environment was a 64 Kbit scale and a measurement temperature of 100 ° C.

  Depending on the presence or absence of the chemical oxide film formation step, the lifetime of the TDDB characteristic was about 1 year without the chemical oxide film treatment, but about 25 years with the chemical oxide film treatment, about 1 digit, It was found that the service life was extended. Here, the lifetime of the TDDB characteristic was estimated by the lifetime at 0.825V. The basis for the calculation is as follows.

  The lifetime value corresponding to 0.825 V is 7.5 in the comparative example, and 8.9 in the embodiment of the present invention.

When converted,
10 ^7.5 (sec) = x1 (year) × (60 × 60 × 24 × 365)
Than,
x1 = 1.0 (year)
10 ^8.9 (sec) = x2 (year) × (60 × 60 × 24 × 365)
Than,
x2 = 25.2 (year)
FIG. 11 is the same as FIG. 6 is a leakage current-voltage characteristic graph depending on the presence or absence of a chemical oxide film forming step of FIG. The measurement environment was room temperature.

  It can be seen that both when the positive bias is applied and when the negative bias is applied, the leakage level is improved by about one digit compared to the case where the chemical oxide film is present but not.

  FIG. 12 corresponds to the FIG. 9 is a TDDB characteristic graph when the TiN film is formed at a low temperature (630 ° C.) and at a high temperature (680 ° C.). The measurement environment was a 64 Kbit scale and a measurement temperature of 100 ° C.

  In the case of forming the TiN film as the upper electrode at a low temperature, the lifetime of the TDDB characteristic was about 25 years. In contrast, in the case of high-temperature film formation with a chemical oxide film treatment, it has been found that the life has been significantly extended over about 100,000 years. Here, the lifetime of the TDDB characteristic was estimated by the lifetime at 0.825V. The basis for the calculation is as follows.

  The lifetime value corresponding to 0.825 V is 8.9 for low temperature film formation and 10.2 for high temperature film formation.

When converted,
10 ^8.9 (sec) = x2 (year) × (60 × 60 × 24 × 365)
Than,
x2 ≒ 25.2 (years)
10 ^12.7 (sec) = x3 (year) × (60 × 60 × 24 × 365)
Than,
x3 ≒ 15.9 × 10 ⁴ (year)
Next, SIMS (Secondary Ion Mass Spectroscopy) analysis results of the capacitor structure of the embodiment of the present invention and the capacitor structure of the comparative example are shown in FIG. It is shown in FIG. FIG. 14 in FIG. The processing flow of the sample used in 13 is shown.

  FIG. 13 shows that the oxygen intensity distribution at m / e = 18 is more distributed to the Poly-Si side in the embodiment of the present invention (with chemical oxide film) as compared with the comparative example. I understand. This is shown in FIG. 6 is a silicon oxide layer (chemical oxide film) formed by chemical oxidation of FIG. 7 is subjected to the modification treatment to the silicon oxynitride film by the plasma treatment of FIG. 8 shows that part of oxygen in the silicon oxide layer has diffused to the lower electrode side by the RTA treatment after the capacitor insulating film 8 is formed.

In the case of the comparative example, FIG. As shown in FIG. 17, a sample of SIMS analysis was prepared by depositing a poly-Si film as a virtual HSG-Si on Bare-Si at 200 nm at 620 ° C., and then in dilute hydrofluoric acid, which is a mixed chemical solution of hydrofluoric acid and pure water. Immersion is performed to remove the natural oxide film on the Si film surface (oxide film removal). Here, the fluorine concentration of dilute hydrofluoric acid was 0.50 vol. %. Thereafter, the same plasma nitriding treatment as in Embodiments 1 and 2 and the formation of a Ta ₂ O ₅ film (10 nm) which is a capacitive insulating film were followed by an RTO treatment at 800 ° C. for 90 seconds in an oxygen atmosphere.

In the case of the embodiment of the present invention, FIG. As shown in FIG. 14, after forming Poly-Si as virtual HSG-Si on Bare-Si at 200 nm at 620 ° C., it is immersed in dilute hydrofluoric acid, which is a mixed chemical solution of hydrofluoric acid and pure water, and the surface of the Si film The natural oxide film is removed (oxide film removal). Subsequently, a chemical oxide film is formed to a thickness of about 1.1 nm by treating with ozone water. Here, the fluorine concentration of dilute hydrofluoric acid was 0.50 vol. %. Thereafter, the same plasma nitriding treatment as in Embodiments 1 and 2 and a Ta ₂ O ₅ film (10 nm) as a capacitive insulating film were formed, followed by an RTO treatment at 800 ° C. for 90 seconds in an oxygen atmosphere.

  The present invention is not limited to the above-described embodiment, and can be variously modified and implemented within the scope of its technical idea.

  The capacitor of the present invention is useful as a capacitor for storing electric charge of a memory cell in a DRAM, which has a high dielectric constant insulating film having a small leakage current and a sufficiently long dielectric breakdown (TDDB) life.

3 is a flowchart illustrating a method for manufacturing a capacitor according to the first and second embodiments of the present invention. It is process sectional drawing (the 1) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 2) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 3) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 4) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 5) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 6) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 7) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is process sectional drawing (the 8) explaining the manufacturing method of the capacitor of Embodiment 1 and 2 of this invention. It is a TDDB characteristic diagram of the capacitor according to the first embodiment of the present invention. It is an IV characteristic diagram of the capacitor according to the first embodiment of the present invention. It is a TDDB characteristic view of the capacitor according to the second embodiment of the present invention. It is a figure which shows the SIMS data in the capacitor structure of embodiment of this invention and a comparative example. It is a creation flow figure of a SIMS sample in the capacitor structure of an embodiment of the invention. It is a cross-section figure of the stacked capacitor of a comparative example. It is a manufacturing process figure of the stacked capacitor of a comparative example. It is a creation flowchart of the SIMS sample in the capacitor structure of a comparative example.

Explanation of symbols

1,11 Silicon substrate 2,12 Capacitance diffusion layer 3,13 Interlayer insulating film (lower layer)
3a, 13a Interlayer insulation film (upper layer)
4,14 Contact hole 5,15 Lower electrode (lower part)
5a, 15a Lower electrode (upper)
6,16 Surface convex part (HSG-Si)
7 Chemical oxide film 8 Silicon oxynitride film 17 Silicon nitride film 9, 18 Capacitance insulating film (Ta ₂ O ₅ film)
10,19 Upper electrode (TiN film)

Claims (5)

Forming an opening in an interlayer insulating film on a semiconductor substrate;
Forming a lower electrode made of polycrystalline silicon having surface irregularities on the inner wall of the opening;
Oxidizing the surface of the lower electrode having the surface irregularities to form a chemical oxide film;
afterwards,
Nitriding the surface of the surface uneven portion of the lower electrode through the chemical oxide film, and modifying the chemical oxide film into a silicon oxynitride film;
afterwards,
Forming a capacitive insulating film made of a metal oxide film on the silicon oxynitride film;
Forming an upper electrode on the capacitive insulating film;
The manufacturing method of the capacitor containing this. The step of forming the chemical oxide film includes:
Cleaning the surface irregularities of the lower electrode to expose the silicon clean surface of the surface irregularities;
Subsequently, wet treatment is performed with a chemical solution having oxidizing power.
The method of manufacturing a capacitor according to claim 1 . The step of forming the upper electrode includes:
A titanium nitride film is formed as the upper electrode at a deposition temperature of 650 ° C. to 700 ° C .;
The method of manufacturing a capacitor according to claim 1 . The step of forming the chemical oxide film includes:
The surface of the lower electrode is oxidized by immersing it in a chemical solution with oxidizing power such as hydrogen peroxide, ozone or nitric acid.
The method of manufacturing a capacitor according to claim 1 . The step of forming the upper electrode includes:
Performed after heat-treating the capacitive insulating film in an oxygen atmosphere;
The method of manufacturing a capacitor according to claim 1 .

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