JP2010278058A - Semiconductor device and method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device having a ferroelectric capacitor with excellent characteristics. <P>SOLUTION: The semiconductor device 1 includes: the ferroelectric capacitor 3 having a ferroelectric film 32 provided between a lower electrode 31 and an upper electrode 33; a first hydrogen barrier film 35 provided on the ferroelectric capacitor 3; an interlayer dielectric 13 provided on the first hydrogen barrier film 35; a contact hole 36 provided on the upper electrode 33 and on the first hydrogen barrier film 35 and interlayer dielectric 13; a conductive film 37 provided in the contact hole 36 and made of nitride of titanium aluminum; a second hydrogen barrier film 38 provided on the conductive film 37 and made of oxide of titanium aluminum; a plug 39 provided on the second hydrogen barrier film 38 in the contact hole 36; and wiring provided on the conductive film 37. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

  Conventionally, a ferroelectric capacitor using spontaneous polarization of a ferroelectric material is known. When a ferroelectric capacitor is used, a nonvolatile memory element capable of low voltage operation and high speed operation can be configured. One memory cell is basically composed of one transistor and one ferroelectric capacitor. Therefore, it is possible to integrate memory elements as highly as a DRAM and to configure a large-capacity memory device.

A ferroelectric capacitor has a structure in which a lower electrode, a ferroelectric film, and an upper electrode are laminated. Ferroelectric film forming materials (ferroelectric materials) include perovskite oxides such as lead zirconate titanate (Pb (Zr, Ti) O ₃ , hereinafter referred to as PZT), bismuth strontium tantalate (SrBi). ₂ Ta ₂ O ₉₎ bismuth layer compound such like are promising.

  A ferroelectric film is generally made of a metal oxide, and its properties deteriorate when reduced. On the other hand, conductive parts such as wirings and plugs that are electrically connected to the lower electrode and the upper electrode become high resistance when oxidized, and electrical characteristics deteriorate. Under such circumstances, a semiconductor device including a ferroelectric capacitor is provided with a hydrogen barrier film that prevents reduction of the ferroelectric film and an oxygen barrier film that prevents oxidation of the conductive portion (for example, Patent Document 1).

JP 2008-28229 A

  According to the technique of Patent Document 1, since the second barrier film (hydrogen barrier film) is provided between the ferroelectric layer and the first insulating layer (interlayer insulating film), hydrogen gas, moisture, etc. This reducing substance is prevented from directly entering the ferroelectric film from the first insulating film. However, the second barrier film is provided with an opening for electrically connecting the upper electrode to the wiring or the like, and the reducing substance may enter the ferroelectric layer through the opening. As a result, the characteristics of the ferroelectric layer may be deteriorated.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a semiconductor device including a ferroelectric capacitor having good characteristics and a method for manufacturing the same.

  The semiconductor device of the present invention includes a ferroelectric capacitor in which a ferroelectric film is provided between a lower electrode and an upper electrode, a first hydrogen barrier film provided on the ferroelectric capacitor, and the first 1 an interlayer insulating film provided on the hydrogen barrier film, a contact hole provided on the upper electrode and in the first hydrogen barrier film and the interlayer insulating film, and provided in the contact hole A conductive film made of nitride of titanium aluminum, a second hydrogen barrier film made of an oxide of titanium aluminum provided on the conductive film, and the contact hole on the second hydrogen barrier film. And a wiring provided on the conductive film.

  In this case, since the second hydrogen barrier film made of titanium aluminum oxide provided on the conductive film is provided, intrusion of a reducing substance such as hydrogen gas through the contact hole is suppressed.

  The method of manufacturing a semiconductor device according to the present invention includes a step of forming a ferroelectric capacitor in which a ferroelectric film is provided between a lower electrode and an upper electrode, and a first hydrogen barrier film on the ferroelectric capacitor. Forming an interlayer insulating film on the first hydrogen barrier film, and forming a contact hole on the upper electrode and in the interlayer insulating film and the first hydrogen barrier film A step of forming a conductive film made of nitride of titanium aluminum in the contact hole, a step of forming a titanium aluminum film on the conductive film, and the titanium aluminum film and the ferroelectric film. A step of performing a heat treatment in an oxygen atmosphere; a step of forming a plug in the contact hole; and a step of forming a wiring over the conductive film. The emissions aluminum film is oxidized, characterized in that it comprises forming a second hydrogen barrier film consisting of oxides of titanium aluminum.

  In this way, in the heat treatment step, the titanium aluminum film is oxidized to form the second hydrogen barrier film made of an oxide of titanium aluminum, so that intrusion of a reducing substance such as hydrogen gas through the contact hole is suppressed. The

  The semiconductor device manufacturing method of the present invention is characterized in that the crystallinity of the ferroelectric film is recovered in the heat treatment step.

  In this way, the process of forming the second hydrogen barrier film by oxidizing the titanium aluminum film and the process of recovering the crystallinity of the ferroelectric film are common, so that the strong and efficient characteristics are enhanced. A semiconductor device having a dielectric capacitor can be manufactured.

1 is a side sectional view showing a schematic configuration of a ferroelectric memory device according to the present invention. (A)-(c) is process drawing which shows the manufacturing method of a ferroelectric memory device. (A)-(c) is process drawing which continues from FIG.2 (c). (A)-(c) is process drawing which continues from FIG.3 (c). (A)-(c) is process drawing which continues from FIG.4 (c).

  Hereinafter, although one embodiment of the present invention is described, the technical scope of the present invention is not limited to the following embodiment. In the following description, various structures are illustrated using drawings, but in order to show the characteristic parts of the structures in an easy-to-understand manner, the structures in the drawings are shown in different sizes and scales from the actual structures. There is.

  FIG. 1 is a side sectional view schematically showing the configuration of the semiconductor device (ferroelectric memory device) of the present embodiment. The ferroelectric memory device 1 includes a large number of memory cells, one of which is shown in FIG. Each memory cell includes a transistor 2 and a ferroelectric capacitor 3. In this embodiment, the memory cell is a stack type.

  Specifically, a plurality of element isolation regions 11 are formed on the surface layer of the silicon substrate 10, and one memory cell is formed between the element isolation regions 11. A transistor 2 is provided on the surface layer of the silicon substrate 10. A first interlayer insulating film 12 is provided so as to cover the transistor 2. A first plug 41 and a second plug 42 are provided through the first interlayer insulating film 12. A ferroelectric capacitor 3 is provided at a position overlapping the first plug 41 on the first interlayer insulating film 12.

  A second interlayer insulating film (interlayer insulating film) 13 is provided so as to cover the ferroelectric capacitor 3. A conductive film 37 is provided so as to penetrate the second interlayer insulating film 13 and overlap the ferroelectric capacitor 3. A third plug (conductive portion) 43 is provided at a position that penetrates the second interlayer insulating film 13 and overlaps the first plug 41. The third plug 43 is electrically connected to the first plug 41 (hereinafter sometimes referred to as a conductive connection). A wiring layer 4 is provided on the second interlayer insulating film 13. The wiring layer 4 is provided with wirings (conductive portions) such as ground lines and bit lines (not shown).

  Here, the ground line is electrically connected to the transistor 2 via the first plug 41 and the third plug 43. The transistor 2 is electrically connected to the ferroelectric capacitor 3 via the second plug 42. The ferroelectric capacitor 3 is electrically connected to the bit line through the conductive film 37. Hereinafter, the components of the ferroelectric memory device 1 will be described in detail.

  The transistor 2 is formed using, for example, a surface layer of a silicon substrate 10 made of single crystal silicon as an active layer. Specifically, a source region 21 and a drain region 22 are formed on the surface layer of the silicon substrate 10. In the surface layer of the silicon substrate 10, a region between the source region 21 and the drain region 22 is a channel region. A gate insulating film 23 is provided to cover the source region 21, the drain region 22, and the channel region. A gate electrode 24 is provided on a portion of the gate insulating film 23 that overlaps the channel region in a planar manner. A side wall 25 is provided around the gate electrode 24 so as to be in contact with the side wall of the gate electrode 24. Each of the source region 21 and the drain region 22 includes a high concentration impurity region and a low concentration impurity region, and a portion overlapping with the sidewall 25 is a low concentration impurity region. The high concentration impurity region of the source region 21 is electrically connected to the first plug 41. The high concentration impurity region of the drain region 22 is electrically connected to the second plug 42.

  The first interlayer insulating film 12 is made of an insulating material such as silicon oxide or silicon nitride. A contact hole that penetrates through the first interlayer insulating film 12 and leads to the high concentration region of the source region 21 and a contact hole that leads to the high concentration region of the drain region 22 are formed. A first plug 41 and a second plug 42 are embedded in the contact holes, respectively. The first plug 41 and the second plug 42 are made of a conductive material such as tungsten, molybdenum, tantalum, titanium, or nickel. Here, the first plug 41, the second plug 42, the third plug 43, and the fourth plug 39 are all made of tungsten.

  The ferroelectric capacitor 3 includes a lower electrode 31, a ferroelectric film 32, and an upper electrode 33. Here, a base conductive portion 34 is provided between the lower electrode 31 and the first interlayer insulating film 12. The base conductive portion 34 is provided in a portion overlapping the second plug 42 and is conductively connected to the second plug 42. The base conductive portion 34 prevents oxidation of the second plug 42 and controls the crystal orientation of the ferroelectric film 32. The base conductive portion 34 is made of a conductive material having self-orientation properties and oxygen barrier properties, such as titanium aluminum nitride (titanium aluminum nitride, TiAlN).

  The lower electrode 31 is provided on the base conductive portion 34 and is electrically connected to the base conductive portion 34. The upper electrode 33 is provided on the ferroelectric film 32. The lower electrode 31 and the upper electrode 33 are composed of a single layer or a plurality of layers of a conductive material. As a film constituting the lower electrode 31 and the upper electrode 33, a film made of at least one of iridium, platinum, ruthenium, rhodium, palladium and osmium, a film made of an alloy thereof, or an oxide thereof Selected from membranes and the like. When a film made of a noble metal such as iridium or platinum is used, the lower electrode 31 is thermally and chemically stable. Here, the lower electrode 31 and the upper electrode 33 are made of a single-layer iridium film.

The ferroelectric film 32 is made of a ferroelectric material whose general formula is ABO ₃ . The A-site metal is composed of, for example, lead or a part of lead replaced with lanthanum, calcium, or strontium. The B-site metal is made of, for example, zirconium or titanium, and one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, and magnesium may be added thereto.

Specific examples of the ferroelectric material include lead zirconate titanate ((Pb (Zr, Ti) O ₃ , hereinafter sometimes referred to as PZT), PZTN added with niobium as the B-site metal, and the like. From the viewpoint of increasing the amount of spontaneous polarization, it is preferable to make the Ti content higher than the Zr content, in which case the crystal structure belongs to a tetragonal crystal from the viewpoint of improving the hysteresis characteristics ( In this case, the ferroelectric film 32 is made of PTZN and has a (111) -oriented perovskite crystal structure belonging to tetragonal crystal.

  A first hydrogen barrier film 35 is provided so as to cover the side and top surfaces of the ferroelectric capacitor 3 and the peripheral portion of the ferroelectric capacitor 3. The first hydrogen barrier film 35 prevents the ferroelectric film 32 from being reduced. The first hydrogen barrier film 35 is made of, for example, aluminum oxide.

  A second interlayer insulating film 13 is provided so as to cover the first hydrogen barrier film 35 and the first interlayer insulating film 12. Similar to the first interlayer insulating film 12, the second interlayer insulating film 13 is made of an insulator such as silicon oxide. A contact hole that penetrates through the second interlayer insulating film 13 and communicates with the first plug 41 is provided. A third plug 43 is embedded in the contact hole. Further, a contact hole 36 that penetrates through the second interlayer insulating film 13 and communicates with the upper electrode 33 is provided.

  A conductive film 37 made of titanium aluminum nitride is provided continuously on the side wall in the contact hole 36 and on the upper electrode 33. A second hydrogen barrier film 38 made of titanium aluminum oxide is provided to cover the conductive film 37 in the contact hole 36. In the contact hole 36, a fourth plug 39 is embedded in a recess having the second hydrogen barrier film 38 as a side wall and a bottom. The conductive film 37 is electrically connected to the bit line.

  In the ferroelectric memory device 1 configured as described above, when a voltage is applied to the gate electrode 24 of the transistor 2, the channel region is turned on. When an electrical signal is supplied from the bit line to the source region 21 with the channel region turned on, the electrical signal is transmitted to the lower portion via the channel region, the drain region 22, the second plug 42, and the base conductive portion 34. It is transmitted to the electrode 31. As a result, a voltage is applied between the lower electrode 31 and the upper electrode 33, and charges (data) are accumulated in the ferroelectric film 32. The ferroelectric memory device 1 is capable of writing data to the ferroelectric capacitor 3 and reading data from the ferroelectric capacitor 3 by switching an electric signal with the transistor 2.

  Since the ferroelectric capacitor 3 holds data by utilizing the polarization inversion of the ferroelectric film 32, the necessity of holding the data by rewriting (refreshing) the data is reduced. Therefore, a memory device with low power consumption can be configured by using the ferroelectric capacitor 3.

In general, when data is repeatedly rewritten in a ferroelectric capacitor, the read signal amount decreases from the initial state. For example, when the rewriting of approximately 10 ¹¹ times the ferroelectric capacitor, it may signal amount becomes unreadable. As a cause of a decrease in signal amount due to rewriting, deterioration of the ferroelectric film is considered. The ferroelectric film is made of a metal oxide or the like, and the reduced portion (deteriorated portion) in the ferroelectric film does not contribute to the polarization inversion. Therefore, the amount of signal decreases as the proportion of the deteriorated portion in the ferroelectric film increases.

  In the ferroelectric memory device 1 of the present embodiment, the side wall and the upper surface of the ferroelectric capacitor 3 are covered with the first hydrogen barrier film 35, so that the deterioration of the ferroelectric film 32 is reduced. . In order to make electrical connection with the ferroelectric capacitor 3, an opening is provided in the first hydrogen barrier film 35 on the upper electrode 33, and a reducing substance (for example, hydrogen) may enter through the opening. It can be. However, the contact hole 36 including the opening of the first hydrogen barrier film 35 is covered with the conductive film 37 on the side wall and the bottom (the top of the upper electrode 33), and the conductive film 37 further forms the second hydrogen barrier film 38. Since it is covered, the reduction of the reducing substance from the opening of the first hydrogen barrier film 35 to the ferroelectric film 32 is significantly reduced. As described above, in the ferroelectric memory device 1, the deterioration of the ferroelectric film 32 is remarkably reduced, and the hysteresis characteristics of the ferroelectric capacitor 3 are excellent. Therefore, the ferroelectric memory device 1 has high durability and high reliability. It is a thing.

  Next, an embodiment of a method for manufacturing a semiconductor device according to the present invention will be described based on the configuration of the ferroelectric memory device 1. FIGS. 2A to 2C, FIGS. 3A to 4C, FIGS. 4A to 4C, and FIGS. 5A to 5C illustrate a method for manufacturing a semiconductor device according to this embodiment. FIG. In FIG. 2B and subsequent figures, the lower layer structure of the first interlayer insulating film 12 is not shown.

  First, as shown in FIG. 2A, an element isolation region 11 is formed on a silicon substrate 10 by, for example, a LOCOS method or an STI method. Then, a gate insulating film 23 is formed on the silicon substrate 10 between the element isolation regions 11 by thermal oxidation or the like. Then, a gate electrode 24 made of polycrystalline silicon or the like is formed on the gate insulating film 23. Then, impurities are implanted at a low concentration into the surface layer of the silicon substrate 10 between the element isolation regions 11 using the gate electrode 24 as a mask. Then, the sidewall 25 is formed using an etch back method or the like. Then, impurities are implanted into the surface layer of the silicon substrate 10 between the element isolation regions 11 using the gate electrode 24 and the sidewall 25 as a mask. Thereby, the source region 21 and the drain region 22 including the low concentration impurity region and the high concentration impurity region are obtained. As described above, the transistor 2 is formed.

  Then, a silicon oxide film is formed on the silicon substrate 10 on which the transistor 2 is formed by, for example, a CVD method to form a first interlayer insulating film 12. Then, the first interlayer insulating film 12 on the source region 21 and the drain region 22 is etched to form a contact hole that exposes the source region 21 and a contact hole that exposes the drain region 22. Then, tungsten is formed in the contact hole and on the first interlayer insulating film 12 by, for example, a CVD method, and tungsten is buried in the contact hole. Then, the tungsten on the first interlayer insulating film 12 is removed by polishing the first interlayer insulating film 12 by a CMP method or the like. In this way, the first plug 41 is embedded in the contact hole on the source region 21, and the second plug 42 is embedded in the contact hole on the drain region 22.

Next, as shown in FIG. 2B, the base conductive portion 34 and the ferroelectric capacitor 3 are formed on the second plug 42 and the first interlayer insulating film 12 around the second plug 42.
Specifically, a nitride of titanium aluminum, for example, is formed on the second plug 42 and the first interlayer insulating film 12 as a material for forming the base conductive portion 34 by sputtering.
Then, for example, iridium is formed as a material for forming the lower electrode 31 on the titanium aluminum nitride film by a sputtering method or the like.
On the iridium film, for example, PZTN is formed as a material for forming the ferroelectric film 32 in an oxygen atmosphere by a sol-gel method (CSD method), an MOCVD method, a sputtering method, or the like.
Then, for example, iridium is formed as a material for forming the upper electrode 33 on the PZTN film by a sputtering method or the like.
Then, a mask pattern such as a hard mask is formed on the upper iridium film. Using the mask pattern as an etching mask, the upper iridium film, PZTN film, lower iridium film, and titanium aluminum nitride film are etched. As described above, the ferroelectric capacitor 3 is formed.

  Since the titanium aluminum nitride is a material having self-orientation, the crystal orientation of the titanium aluminum nitride film is improved. The iridium film and the PZTN film have a good crystal orientation reflecting the crystal orientation of the titanium aluminum nitride film as a base. Further, although the PZTN film is formed in an oxygen atmosphere, since the titanium aluminum nitride film has an oxygen barrier property, oxidation of the first plug 41 and the second plug 42 is prevented.

  Next, as shown in FIG. 2C, the first and second insulating interlayers 12 are continuously covered so as to continuously cover the side wall and upper surface of the ferroelectric capacitor 3, the side wall of the base conductive portion 34, and the periphery of the base conductive portion 34. A hydrogen barrier film 35 is formed. Here, an aluminum oxide film is formed over almost the entire area above the silicon substrate 10, and the first hydrogen barrier film 35 is formed by patterning this film.

  Next, as shown in FIG. 3A, a second interlayer insulating film 13 is formed so as to cover the first hydrogen barrier film 35 and the first interlayer insulating film 12. Here, a silicon oxide film is formed by a CVD method using a source gas containing tetraethoxysilane to form the second interlayer insulating film 13. Reducing substances such as hydrogen gas and moisture may be generated by the reaction of the raw material gas. Since the ferroelectric capacitor 3 is covered with the first hydrogen barrier film 35, the deterioration due to the reduction of the ferroelectric film 32 is remarkably reduced.

  Next, as shown in FIG. 3B, the upper surface of the upper electrode 33 is exposed through the second interlayer insulating film 13 and the first hydrogen barrier film 35 on the upper electrode 33 of the ferroelectric capacitor 3. A contact hole 36 is formed. Note that oxygen defects or the like in the ferroelectric film 32 may be repaired by heat-treating the ferroelectric capacitor 3 in an oxygen atmosphere before forming the second interlayer insulating film 13 or after forming the contact hole 36. it can.

  Next, as shown in FIG. 3C, the upper surface of the upper electrode 33 exposed in the contact hole 36, the side wall of the contact hole 36, and the second interlayer insulating film 13 around the contact hole 36 are continuously covered. Then, a titanium aluminum nitride film 37a is formed. Then, a titanium aluminum film 38a is formed so as to cover the titanium aluminum nitride film 37a. Here, the titanium aluminum nitride film 37a and the titanium aluminum film 38a are successively formed by a sputtering method. Specifically, the silicon substrate 10 in which the contact hole 36 is formed is installed in a film forming chamber of a sputtering apparatus. Titanium aluminum is used as a target, and nitrogen gas is circulated as a reaction gas in the film formation chamber to form a titanium aluminum nitride film. Then, the supply of nitrogen gas is stopped and titanium aluminum film is formed as it is.

  Next, as shown in FIG. 4A, the crystallinity of the ferroelectric film 32 is recovered by heat-treating the silicon substrate 10 on which the titanium aluminum nitride film 37a and the titanium aluminum film 38a are formed in an oxygen atmosphere. The titanium aluminum film 38a is oxidized by this heat treatment to form a titanium aluminum oxide film 38b.

  Next, as shown in FIG. 4B, the titanium interlayer nitride film 37a and the titanium aluminum oxide film 38b on the second interlayer insulating film 13 are removed by polishing the second interlayer insulating film 13 by CMP. . In this manner, a conductive film 37 made of titanium aluminum nitride is formed on the side wall in the contact hole 36. Further, a second hydrogen barrier film 38 made of titanium aluminum oxide and covering the conductive film 37 in the contact hole 36 is formed.

  Next, as shown in FIG. 4C, a contact hole 43 a that penetrates the second interlayer insulating film 13 on the first plug 41 and exposes the upper surface of the first plug 41 is formed. Since the first plug 41 is covered with the second interlayer insulating film 13 after the second interlayer insulating film 13 is formed and before the contact hole 43a is formed, the oxidation of the first plug 41 is reduced. .

  Next, as shown in FIG. 5A, in the contact hole 43a, in the contact hole 36, in the recess having the second hydrogen barrier film 38 as the inner wall, and on the second interlayer insulating film 13, the third Tungsten is formed in a reducing atmosphere as a material for forming the plug 43. Since tungsten is formed in a reducing atmosphere, a low-resistance tungsten film 43b can be formed. Further, when a part of the first plug 41 is oxidized, the first plug 41 is also reduced and becomes low resistance. As for the ferroelectric film 32, the second hydrogen barrier film 38 is provided so as to cover the side wall side and the bottom side in the contact hole 36, so that the ferroelectric film 32 is prevented from being reduced.

  Next, as shown in FIG. 5B, the tungsten film 43b on the second interlayer insulating film 13 is removed by polishing the second interlayer insulating film 13 by CMP. In this manner, the third plug 43 is embedded in the contact hole 43a, and the fourth plug 39 is embedded in a portion (in the recess) surrounded by the second hydrogen barrier film 38. Further, after the third plug 43 is buried, the fourth plug 39 may be buried by forming the contact hole 43a. As shown in FIG. 5C, the ferroelectric memory device 1 shown in FIG. 1 is obtained by forming the wiring layer 4 on the second interlayer insulating film 13 or the like.

In the semiconductor device manufacturing method of the present embodiment as described above, the titanium aluminum film 38a is continuously formed in the same film forming chamber using the same target as the titanium aluminum nitride film 37a. The titanium aluminum film 38a can be formed efficiently. In addition, by performing heat treatment in an oxygen atmosphere, the crystallinity of the ferroelectric film 32 is recovered and the titanium aluminum film 38a is oxidized, so that the crystallinity of the ferroelectric film 32 can be improved. In addition, the second hydrogen barrier film 38 can be formed efficiently. Since the second hydrogen barrier film 38 is formed covering the inner wall side and the bottom side of the contact hole 36, the third plug 43 is formed in a reducing atmosphere while preventing the ferroelectric film 32 from being reduced. be able to. As a result, the ferroelectric capacitor 3 can have good hysteresis characteristics, and the conductive portions such as the third plug 43 that transmit an electrical signal to the ferroelectric capacitor 3 can have good electrical characteristics. .
As described above, according to the semiconductor device manufacturing method of the present embodiment, the ferroelectric memory device 1 having good characteristics can be efficiently manufactured at low cost.

  The technical scope of the present invention is not limited to the above embodiment. Various modifications are possible without departing from the gist of the present invention. For example, the contact hole 43a may be formed together with the contact hole 36. In this case, nitride of titanium aluminum and titanium aluminum are continuously formed in a lump in the contact hole 36, the contact hole 43a, and the second interlayer insulating film 13. Then, by performing heat treatment in an oxygen atmosphere, the crystallinity of the ferroelectric film 32 is restored and titanium aluminum is oxidized. Then, tungsten is formed to cover the titanium aluminum oxide film. Then, the tungsten film, titanium aluminum oxide film, and titanium aluminum nitride film on the second interlayer insulating film 13 are removed by CMP. In this way, the contact hole 43a can be formed together with the contact hole 36, and the tungsten film can be removed together with the titanium aluminum oxide film and the titanium aluminum nitride film. Therefore, the number of steps can be reduced, and a ferroelectric memory device can be manufactured efficiently at low cost.

DESCRIPTION OF SYMBOLS 1 ... Ferroelectric memory device (semiconductor device), 2 ... Transistor, 3 ... Ferroelectric capacitor, 31 ... Lower electrode, 32 ... Ferroelectric film, 33 ... Upper part Electrode 35 ... first hydrogen barrier film 36 ... contact hole 37 ... conductive film 38 ... second hydrogen barrier film 43 ... third plug (conductive part)

Claims (3)

A ferroelectric capacitor in which a ferroelectric film is provided between the lower electrode and the upper electrode;
A first hydrogen barrier film provided on the ferroelectric capacitor;
An interlayer insulating film provided on the first hydrogen barrier film;
A contact hole on the upper electrode and provided in the first hydrogen barrier film and the interlayer insulating film;
A conductive film made of titanium aluminum nitride provided in the contact hole;
A second hydrogen barrier film made of titanium aluminum oxide provided on the conductive film;
A plug provided on the second hydrogen barrier film and in the contact hole;
Wiring provided on the conductive film;
A semiconductor device comprising: Forming a ferroelectric capacitor in which a ferroelectric film is provided between the lower electrode and the upper electrode;
Forming a first hydrogen barrier film on the ferroelectric capacitor;
Forming an interlayer insulating film on the first hydrogen barrier film;
Forming a contact hole on the upper electrode and in the interlayer insulating film and the first hydrogen barrier film;
Forming a conductive film made of nitride of titanium aluminum in the contact hole;
Forming a titanium aluminum film on the conductive film;
Heat-treating the titanium aluminum film and the ferroelectric film in an oxygen atmosphere;
Forming a plug in the contact hole;
Forming a wiring on the conductive film,
The method of manufacturing a semiconductor device, wherein the heat treatment step includes oxidizing the titanium aluminum film to form a second hydrogen barrier film made of an oxide of titanium aluminum.   3. The method of manufacturing a semiconductor device according to claim 2, wherein the crystallinity of the ferroelectric film is recovered in the heat treatment step.

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