Method of manufacturing capacitor, capacitor and method of forming dielectric film for use in capacitor

Provided are a method of manufacturing a capacitor capable of achieving a high dielectric constant property and a low leakage current, a capacitor, and a method of forming a dielectric film used in the capacitor. The capacitor is fabricated by forming a lower electrode layer on a substrate; forming a first TiO2 film having an interface control function on the lower electrode layer; forming a ZrO2-based film on the first TiO2 film; performing an annealing process for crystallizing ZrO2 in the ZrO2-based film, after forming the ZrO2-based film; forming a second TiO2 film which serves as a capacity film on the ZrO2-based film; and forming an upper electrode layer on the second TiO2 film.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of Japanese Patent Application No. 2012-023469, filed on Feb. 6, 2012, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing a capacitor, a capacitor, and a method of forming a dielectric film used in the capacitor.

2. Description of the Related Art

Recently, from demands for high integration and high speed LSI (large-scale integration), design rules of a semiconductor device configuring the LSI have been miniaturized further. Accompanying with this, increase of a capacity of a capacitor used in a DRAM is requested, and accordingly, increase of dielectric constant of a dielectric film used in the capacitor is also required.

As a dielectric film having high dielectric constant and used in such a capacitor of a DRAM, a zirconium oxide (ZrO2) film is suggested (for example, as in Patent Document 1).

However, in a case where a ZrO2film alone is applied as a dielectric film of a DRAM capacitor, the ZrO2film cannot meet the high-K property required as a dielectric film of a next generation DRAM. Thus, a titanium oxide (TiO2) film having higher dielectric constant is highlighted as a next generation dielectric film (for example, as in Patent Document 2).

Also, Patent Document 3 discloses a capacitor using a two-layered metal oxide film that contains Ti such as a ZrO2film or a TiO2film as a dielectric film.

As disclosed in the Patent Document 2, when the TiO2film is used as the dielectric film, there is a problem that the TiO2basically has a high leakage current and low stability. Thus, to address the above problem, a technology of mixing a dopant such as AlO with TiO2, using a RuO2film as an electrode material, or forming a Ru film or a Pt film as a base film is being researched; however, the above technology may not provide a sufficient property or have a high technical hurdle. Thus, the DRAM capacitor using the dielectric film that mainly includes the TiO2film has not been commercialized yet.

Also, since the ZrO2film is likely to generate oxygen deficit, even if the dielectric film having a two-layered metal oxide film including Ti such as the ZrO2film and the TiO2film as disclosed in the Patent Document 3 is used, it is difficult to achieve a desired level of high dielectric constant and low leakage current.(Patent Document 1) Japanese Laid-open Patent Publication No. 2001-152339(Patent Document 2) Japanese Laid-open Patent Publication No. 2004-296814(Patent Document 3) International Application Publication No. 2010/082605 Pamphlet

SUMMARY OF THE INVENTION

The present invention provides a method of manufacturing a capacitor capable of achieving both of high dielectric constant and low leakage current properties, a capacitor, and a method of forming a dielectric film used in the capacitor.

According to an aspect of the present invention, there is provided a method of manufacturing a capacitor, the method including: forming a lower electrode layer on a substrate; forming a first TiO2film having an interface control function on the lower electrode layer; forming a ZrO2-based film on the first TiO2film; performing an annealing process for crystallizing ZrO2in the ZrO2-based film, after forming the ZrO2-based film; forming a second TiO2film which serves as a capacity film on the ZrO2-based film; and forming an upper electrode layer on the second TiO2film.

According to another aspect of the present invention, there is provided a capacitor including: a lower electrode layer formed on a substrate; a first TiO2film which is formed on the lower substrate and has an interface control function; a ZrO2-based film which is formed on the first TiO2film and is annealed for being crystallized; a second TiO2film which is formed on the ZrO2-based film and serves as a capacity film; and an upper electrode layer which is formed on the second TiO2film.

According to another aspect of the present invention, there is provided a method of forming a dielectric film, the method including: forming a first TiO2film having an interface control function on a lower electrode layer formed on a substrate; forming a ZrO2-based film on the first TiO2film; performing an annealing process for crystallizing ZrO2in the ZrO2-based film, after forming the ZrO2-based film; and forming a second TiO2film which serves as a capacity film on the ZrO2-based film.

According to another aspect of the present invention, there is provided a recording medium storing a program operating in a computer for controlling a film forming apparatus, wherein the program controls the computer to make the film forming apparatus execute the method of forming the dielectric film according to the above aspect of the present invention.

The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention achieved on the basis of the findings given above will now be described with reference to the accompanying drawing. In the following description, the constituent elements having substantially the same function and arrangement are denoted by the same reference numerals, and a repetitive description will be made only when necessary.

Hereinafter, the present invention will be described in detail by explaining exemplary embodiments of the invention with reference to the attached drawings.

<Embodiments of a Method of Fabricating a Capacitor>

First, a method of manufacturing a capacitor according to an embodiment of the present invention will be described below. Here, a cylinder type capacitor is exemplary shown.

FIG. 1is a flowchart describing a method of manufacturing a capacitor according to an embodiment of the present invention, andFIGS. 2A through 2Gare cross-sectional views showing processes for manufacturing the capacitor.

First, on a semiconductor wafer W in which a plurality of contacts114formed of, for example, Ti are formed to correspond to locations where capacitors will be formed, an insulation layer102formed of SO2or the like is formed, and then, portions of the insulation layer102, which correspond to the contacts114, are removed by an etching process to form recess portions116of high aspect ratio. In addition, a lower electrode layer104is formed on a surface of the structure which is formed by the above processes to electrically connect to the contacts114, and an entire surface is polished by, for example, a chemical mechanical polishing (CMP) method, so that the lower electrode layer104only remains on inner walls of the concave portions116(operation1,FIG. 2A).

The lower electrode layer104is typically formed as a TiN film, and may be formed by a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method by using, for example, a TiCl4gas as a Ti material gas and using, for example, a NH3gas as a nitriding gas.

Next, the insulation layer102is removed by a wet etching process to remain the lower electrode layer104of a cylindrical shape (operation2,FIG. 2B).

In addition, a first TiO2film106is formed on the lower electrode layer104of the cylindrical shape (operation3,FIG. 2C). The first TiO2film106is formed to provide an interface control in regard to the lower electrode layer104, and restrains leakage current. In order to obtain the above function, the first TiO2film106may have a thin thickness of about 0.2 to 1.5 nm. If the thickness is less than about 0.2 nm, it is difficult to form the film, and if the thickness is greater than about 1.5 nm, an equivalent oxide thickness (EOT) or a capacitance equivalent thickness (CET) of the dielectric film is increased too much. More preferably, the thickness of the first TiO2film106may be about 0.2 to 1.0 nm. The first TiO2film106may be appropriately formed by the CVD method or the ALD method, as will be described later. The first TiO2film106may be doped with Al, Si, Ta, Nb, or the like.

Next, a ZrO2-based film108is formed on the first TiO2film106(operation4,FIG. 2D). The ZrO2-based film108is crystallized through a subsequent annealing process and serves to increase a dielectric constant of a second TiO2film110formed thereon. To do this, the ZrO2-based film108may have a thickness of about 1 to 10 nm. If the thickness is less than about 1 nm, it is difficult to crystallize the ZrO2through the annealing, and if the thickness is greater than about 10 nm, the dielectric constant of the dielectric film may be insufficient. More preferably, the thickness of the ZrO2— based film108may be about 1 to 5 nm. The ZrO2— based film108may be appropriately formed by the CVD method or the ALD method, as will be described later. The ZrO2-based film108may include ZrO2alone. ZrO2doped with Al, Si, or the like, a ZAZ structure, in which a ZrO2film and Al2O3film are stacked, and a LAZO structure, in which a ZrO2film and an Al2O3film are alternately formed by an ALD method.

Next, an annealing process for improving crystallization property of the ZrO2is performed to the structure in which the ZrO2-based film108is formed (operation5,FIG. 2E). The annealing is preferably performed within a temperature range from about 300° C. to 600° C. If the annealing temperature is less than about 300° C., it is difficult to crystallize the ZrO2in the ZrO2-based film108, and if the annealing temperature is higher than about 600° C., devices that have been formed before forming the capacitor may be thermally affected. More preferably, the annealing may be performed within a temperature range of about 350° C. to 600° C. The annealing may be performed under an oxygen atmosphere using an O2gas, an inert gas atmosphere using an N2gas, or a reduction atmosphere using an H2gas.

Next, the second TiO2film110is formed on the ZrO2-based film110(operation6,FIG. 2F). The second TiO2film110is formed as a main capacity film. The second TiO2film110may be formed by the CVD or ALD method, as will be described later. The TiO2may have two kinds of crystal structures, that is, anatase type and rutile type. The anatase is a low temperature phase and has a relative dielectric constant of about 40, whereas the rutile is a high temperature phase and has a relative dielectric constant of 80 or greater. Under a temperature of about 300° or lower where the film is formed by using the CVD method or the ALD method, the anatase of the low temperature phase is grown, and thus. It is difficult to obtain a high dielectric constant. However, when the ZrO2-based film108is crystallized by the annealing process, the second TiO2film110formed on the ZrO2-based film108has the rutile structure. Therefore, the second TiO2film110has a high dielectric constant, and contributes to a low EOT (low CET). Also, since the second TiO2film110has the rutile type crystal structure, a leakage current to an upper electrode layer112formed on the second TiO2film110may be reduced. The second TiO2film110may have a film thickness of about 1 to 20 nm. If the film thickness is less than about 1 nm, the leakage current is increased even though the EOT is good. If the film thickness is greater than about 20 nm, the EOT is increased although the leakage current is reduced. More preferably, the film thickness may be about 1 to 10 nm, and most preferably, about 5 to 10 nm. The second TiO2film110may be doped with Al, Si, Ta, Nb, or the like.

Next, the upper electrode layer112is formed on the second TiO2film110to complete the capacitor (operation7,FIG. 2G). Like the lower electrode layer104, the upper electrode layer112is typically formed as a TiN film via the CVD method or the ALD method by using, for example, a TiCl4gas as a Ti material gas and using, for example, an NH3gas as a nitriding gas.

The capacitor120includes the lower electrode layer104, the first TiO2film106, the ZrO2-based film108that is crystallized by the annealing process, the second TiO2film110, and the upper electrode layer112. Among these, the first TiO2film106, the ZrO2-based film108, and the second TiO2film110constitute a dielectric film. A total thickness of the dielectric film may be about 5 to 25 nm, and more preferably, about 5 to 15 nm.

As described above, since the thin first TiO2film106for interface control is formed on the lower electrode layer104, the leakage current to the lower electrode layer104may be restrained. In addition, after forming the ZrO2-based film108on the first TiO2film106, the annealing process for crystallizing the ZrO2is performed, and thus, the ZrO2of the ZrO2-based film108may be crystallized, and the second TiO2film110which is formed on the ZrO2-based film108and serves as a capacity film can be grown to have the rutile structure. Accordingly, the dielectric constant of the second TiO2film110can be improved, and the leakage current can be restrained. As such, the high dielectric constant property, that is, the low EOT (low CET), and the low leakage current can be compatibly achieved. Also, a TiN film that is conventionally used can be used as an electrode material, and a special material or a base layer is not necessary. Thus, there is no difficulty in manufacturing the capacitor.

The structure of the capacitor is not limited to the cylinder type, but may be formed as various types. For example, the capacitor may have a filler type structure that is more advantageous for the fine structure. As shown inFIG. 3, a filler type capacitor120′ is fabricated by forming the first TiO2film106on a filler-shaped lower electrode layer104′, forming the ZrO2-based film108, crystallizing the ZrO2of the ZrO2-based film108through the annealing process, forming the second TiO2film110, and forming the upper electrode layer112, in the same order as that of manufacturing the above capacitor120.

<Method of Forming a Dielectric Film>

Next, a method of forming a dielectric film including the first TiO2film106, the ZrO2-based film108, and the second TiO2film110will be described in more detail below.

[Example of a Film Forming Apparatus Used to Form the Dielectric Film]

FIG. 4is a longitudinal sectional view of an example of a film forming apparatus100for forming the dielectric film, andFIG. 5is a transverse sectional view of the film forming apparatus100ofFIG. 4. InFIG. 5, a heating apparatus is omitted.

The film forming apparatus100includes a processing chamber1formed as a cylinder having opened lower end and a ceiling. The processing chamber1may be entirely formed of, for example, quartz A ceiling plate2formed of quartz is provided and sealed on the ceiling in the processing chamber1. A manifold3formed of, for example, a stainless steel cylinder, is connected to the lower opening of the processing chamber1via a sealing member104such as an O-ring.

The manifold3supports a lower portion of the processing container1. A wafer boat5that is formed of quartz and holds a plurality of semiconductor wafers W (hereinafter, referred to as wafers) as processing targets, for example, about 50 to 100 semiconductor wafers W, in multiple stages is configured to be inserted into the processing container1from a lower portion of the manifold3. The wafer boat5includes three pillars6(refer toFIG. 5), and the plurality of wafers W are supported by grooves formed in the pillars6.

The wafer boat5is placed on a table8via a thermos tube7formed of quartz. The table8is supported on a rotary shaft10that penetrates through a cover unit9which opens/closes the lower opening of the manifold3and is formed of, for example, stainless steel.

A magnetic fluid seal11, for example, is provided on a penetration portion of the rotary shaft10so as to airtightly seal and rotatably support the rotary shaft10, A sealing member12formed of, for example, an O-ring, is provided between a peripheral portion of the cover unit9and the lower end portion of the manifold3. Accordingly, a sealing property in the processing container1may be held.

The rotary shaft10is attached to a leading edge of an arm13supported by an elevation mechanism (not shown), for example, a boat elevator, so that the wafer boat5, the cover unit9, and the like are integrally elevated to be inserted into/withdrawn from the processing chamber1. Otherwise, the table8is fixedly formed at the cover unit9so as to perform processes of the wafers W without rotating the wafer boat5.

The film forming apparatus100includes an oxidizing agent supply mechanism14for supplying a oxidizing agent gas, for example, an O3gas, into the processing chamber1, a Zr source gas supply mechanism15for supplying a Zr source gas (Zr material gas) into the processing chamber1, and a Ti source gas supply mechanism16for supplying a Ti source gas (Ti material gas) into the processing chamber1. Also, the film forming apparatus100also includes a purge gas supply mechanism30for supplying an inert gas, for example, an N2gas, as a purge gas into the processing chamber1.

The oxidizing agent supply mechanism14includes an oxidizing agent supply source17, an oxidizing agent pipe18for inducing the oxidizing agent from the oxidizing agent supply source17, and an oxidizing agent diffusion nozzle19which is connected to the oxidizing agent pipe18, is formed of a quartz pipe, penetrates into the manifold3through a side wall of the manifold3, bends upward and extends perpendicularly. A plurality of gas ejection holes19aare formed in the oxidizing agent diffusion nozzle19at predetermined intervals at the perpendicular portion of the oxidizing agent diffusion nozzle19, so that the oxidizing agent, for example, the O3gas, may be evenly discharged from the gas ejection holes19atoward the processing chamber1in a horizontal direction. An H2O gas, an O2gas, an NO2gas, an NO gas, and an N2O gas may be used as the oxidizing agent, in addition to the above O3gas. A plasma generation mechanism may be provided to plasmatize the oxidizing agent so as to improve reactivity. Also, an O2gas and an H2gas may be used to cause radical oxidation. When using the O3gas, an ozonizer generating the O3gas is used as the oxidizing agent supply source17.

The Zr source gas supply mechanism15includes a Zr source storage container20in which Zr source formed of a Zr compound is stored, a Zr source pipe21for inducing liquid Zr source from the Zr source storage container20, a vaporizer22connected to the Zr source pipe21for vaporizing the Zr source, a Zr source gas pipe23for inducing a Zr source gas generated by the vaporizer22, and a Zr source gas diffusion nozzle24which is formed of quartz pipe, is connected to the Zr source gas pipe23, penetrates into the manifold3through a side wall of the manifold3, bends upward and extends perpendicularly. A carrier gas pipe22afor supplying an N2gas as a carrier gas is connected to the vaporizer22. A plurality of gas ejection holes24aare formed in the Zr source gas diffusion nozzle24at predetermined intervals in a length direction of the Zr source gas diffusion nozzle24, so that the Zr source gas may be evenly discharged from the gas ejection holes24ain a horizontal direction.

As the Zr compound, for example, a Zr compound including a cyclopentadienyl ring, such as cyclopentadienyl tris(dimethylamino)zirconium (ZrCp(NMe2)3; CPDTMZ), methycyclopentadienyl tris(dimethylamino)zirconium (Zr(MeCp)(NMe2)3; MCPDTMZ), and the like may be appropriately used.

The Ti source gas supply mechanism16includes a Ti source storage container25in which a Ti source formed of a Ti compound is stored, a Ti source pipe26for inducing a liquid state Ti source from the Ti source storage container25, a vaporizer27connected to the Ti source pipe26to vaporize the Ti source, a Ti source gas pipe28for inducing a Ti source gas generated by the vaporizer27, and a Ti source gas diffusion nozzle29which is formed of a quartz pipe, is connected to the Ti source gas pipe28, penetrates into the manifold3through a side wall of the manifold3, bends upward and extends perpendicularly. A carrier gas pipe27afor supplying an N2gas as a carrier gas is connected to the vaporizer27. A plurality of gas ejection holes29aare formed in the Ti source gas diffusion nozzle29at predetermined intervals in a length direction of the Ti source gas diffusion nozzle29, so that the Ti source gas may be evenly discharged from the gas ejection holes29ainto the processing chamber1in a horizontal direction.

As the Ti compound, for example, a compound including a cyclopentadienyl ring, such as methycyclopentadienyl tris(dimethylamino)titanium (Ti(MeCp)(NMe2)3; MCPDTMT) may be appropriately used.

Additionally, the purge gas supply mechanism30includes a purge gas supply source31, a purge gas pipe32for inducing a purge gas from the purge gas supply source31, and a purge gas nozzle33connected to the purge gas pipe32and penetrating a side wall of the manifold3. An inert gas, for example, an N2gas, may be used as the purge gas.

An opening/closing valve18aand a flow controller18bsuch as a mass flow controller are provided in the oxidizing agent pipe18so that the oxidizing agent gas can be supplied while controlling a flow rate thereof. Also, an opening/closing valve32aand a flow controller32bsuch as a mass flow controller are provided in the purge gas pipe32so that the purge gas can be supplied while controlling a flow rate thereof.

A Zr source pressure feed pipe20ais inserted in the Zr source storage container20, and the liquid type Zr source is fed into the Zr source pipe21by supplying a pressure feed gas such as a He gas from the Zr source pressure feed pipe20a. A flow controller21asuch as a liquid mass flow controller is provided in the Zr source pipe21, and a valve23ais provided in the Zr source gas pipe23.

A Ti source pressure feed pipe25ais inserted in the Ti source storage container25, and the Ti source liquid is fed into the Ti source pipe26by supplying a pressure feed gas such as a He gas from the Ti source pressure feed pipe25a. A flow controller26asuch as a liquid mass flow controller is provided in the Ti source pipe26, and a valve28ais provided in the Ti source gas pipe28.

The oxidizing agent diffusion nozzle19for discharging the oxidizing agent is provided in a recess portion1aof the processing chamber1, and the Zr source gas diffusion nozzle24and the Ti source gas diffusion nozzle29are provided so that the oxidizing agent diffusion nozzle19can be interposed therebetween.

An exhaust hole37for vacuum exhausting the processing chamber1is formed at a side opposite to the oxidizing agent diffusion nozzle19, the Zr source gas diffusion nozzle24, and the Ti source gas diffusion nozzle29in the processing chamber1. The exhaust hole37is formed thin and long by shaving off the side wall of the processing chamber1in an up-and-down direction. An exhaust hole cover member38having a U-shaped cross-section to cover the exhaust hole37is welded and attached to a portion which corresponds to the exhaust hole37in the processing chamber1. The exhaust hole cover member38extends upward along the side wall of the processing chamber1, and defines a gas outlet39at an upper portion of the processing chamber1. A vacuum exhaustion mechanism (not shown) which includes a vacuum pump and the like and performs vacuum suction is provided to the gas outlet39. A heating unit40formed as a cylinder for heating the processing chamber1and the wafers W in the processing chamber1is provided to surround an outer circumference of the processing chamber1.

Also, as described above, the ZrO2-based film may be doped with Al, Si, or the like, and may have the ZAZ structure or the LAZO structure, and the first and second TiO2films may be doped with Al, Si, Ta, Nb, and the like. In this case, a supply mechanism for supplying a material of doped element or a material of Al when forming the ZAZ structure or the LAZO structure may be additionally provided.

Control of each of the components of the film forming apparatus100, for example, supplying and stopping of each gas by opening/closing the opening/closing valves18a,23a,28a, and32a, controlling of the flow rate of the gas or the liquid source by using the flow controller18b,21a,26a, and32b, switching of the gas introduced in the processing chamber1, controlling of the heating unit40, and the like are performed by a controller50formed of, for example, a micro processor (computer). A user interface51including a keyboard that receives an input operation of a command or the like for an operator to control the film forming apparatus100or a display that visibly displays an operating state of the film forming apparatus100is connected to the controller50.

In addition, a memory unit52for storing a controlling program for performing the various processes performed in the film forming apparatus100under a control of the controller50or storing a program for performing a process in each of components of the film forming apparatus100according to processing condition, that is, a recipe, is connected to the controller50. The recipe is recorded in a recording medium of the memory unit52. The recording medium may be a fixed unit such as a hard disk, or a portable unit such as a CD-ROM, a DVD, a flash memory, or the like. Also, the recipe may be appropriately transferred from another device via, for example, an exclusive line.

In addition, if necessary, a certain recipe is called out of the memory unit52by a command or the like from the user interface51, and executed in the controller50, and thus a predetermined process in the film forming apparatus100is performed under the control of the controller50. That is, the recording medium of the memory unit52stores a program (that is, a processing recipe) for executing a film forming method that will be described below, and the program controls the film forming apparatus100to make the controller50execute the film forming method of the dielectric film that will be described below.

[Forming of a Dielectric Film by the Film Forming Apparatus]

Next, a method of forming the dielectric film by the film forming apparatus100configured as above will be described below.

First, the wafer boat5on which a plurality of, for example, about 50 to 100, wafers W are placed under room temperature is elevated to be loaded in the processing chamber1at a predetermined temperature from a lower portion of the processing chamber1, and the cover unit9closes the lower opening of the manifold3to seal the processing chamber1. In addition, the inside of the processing chamber1is maintained at predetermined processing pressure by performing a vacuum suction of the inside of the processing chamber1, and at the same time, a power supply to the heating unit40is controlled to increase the temperature of the wafers W to maintain the processing temperature. Then, a film forming process begins in a state where the wafer boat5is rotated.

When forming the dielectric film, as described above, processes of forming the first TiO2film, forming the ZrO2-based film, annealing, and forming the second TiO2film are performed, and the above processes are performed as below.

1. Process of Forming the First TiO2Film

The first TiO2film is formed by using the above described Ti source gas formed of the Ti compound and the oxidizing agent, while the heating unit40heats the so processing chamber1to a temperature of about 200 to 300° C. In particular, as shown in a timing chart ofFIG. 6, a TiO2film having a predetermined film thickness is formed by performing, repeatedly and a plurality of times, a cycle of TiO2film forming operation via the ALD method, herein a cycle of TiO2film forming operation includes a step S1for supplying the Ti source gas to the processing chamber1to be adsorbed on a ZrO2film, a step S2for purging the inside of the processing chamber1by using a purge gas, a step S3for supplying a oxidizing agent gas, for example, an O3gas, to the processing chamber1to oxidize the Ti source gas, and a step S4for purging the inside of the processing chamber1with the purge gas. Also, as described above, the first TiO2film can be doped with the Al, Si, Ta, Nb, and the like, and in this case, a step of supplying a material of the element by the number of times according to a doped amount may be inserted in the repeated cycle.

In the step S1, the Ti source storage container25of the Ti source gas supply mechanism16supplies the Ti compound that is the Ti source, the vaporizer27vaporizes the Ti compound to generate the Ti source gas, and the Ti source gas is supplied to the processing chamber1for a time period of T1from the gas ejection holes29avia the Ti source gas pipe28and the Ti source gas diffusion nozzle29. Accordingly, the Ti source gas is adsorbed on the lower electrode.

The time period T1of the step S1may be, for example, about 0.1 to 1800 sec. In addition, a flow rate of the Ti source may be, for example, about 0.01 to 10 ml/min (ccm). Also, at that time, a pressure in the processing chamber1may be, for example, about 0.3 to 66650 Pa.

In the step S3for supplying the oxidizing agent, the oxidizing agent, for example, the O3gas, is ejected from the oxidizing agent supply source17of the oxidizing agent supply mechanism14via the oxidizing agent pipe18and the oxidizing agent diffusion nozzle19. Accordingly, the Ti source adsorbed on the lower electrode is oxidized to form the TiO2film.

A time period T3of the step S3may be within a range of about 0.1 to 1800 sec. A flow rate of the oxidizing agent may vary depending on the number of loaded wafers W or a kind of the oxidizing agent; however, when the O3gas is used as the oxidizing agent gas and the number of loaded wafers W is about 50 to 100, the flow rate of the oxidizing agent may be, for example, about 1 to 500 g/Nm3. Also, the pressure in the processing chamber1may be, for example, about 0.3 to 66650 Pa.

The steps S2and S4are performed to remove remaining gas in the processing chamber1after the step S1and step S3, so as to generate a desired reaction in a next step. The purge gas, for example, an N2gas, is supplied to the processing chamber1from the purge gas supply source31of the purge gas supply mechanism30via the purge gas pipe32and the purge gas nozzle33, so as to purge the inside of the processing chamber1. In this case, the vacuum suction and the supply of the purge gas are performed repeatedly to improve an efficiency of removing the remaining gas. Time periods T2and T4for performing the step S2and S4may be, for example, about 0.1 to 1800 sec. In addition, the pressure in the processing chamber1may be, for example, about 0.3 to 66650 Pa. Here, in the step S2after the step S1for supplying the Ti source gas and in the step S4after the step S3for supplying the oxidizing agent, a time for vacuum suction and a time for supplying the purge gas may be switched due to a difference of properties of the gas discharge. In particular, it takes longer to discharge the gas after performing the step S1than after the step S3and accordingly the time for performing the step S2after the step S1may be increased.

2. Process of Forming the ZrO2-Based Film

The ZrO2-based film is formed by using the above described Zr source gas formed of the Zr compound and the oxidizing agent, while heating the inside the processing chamber1to a temperature of about 200 to 300° C. by using the heating unit40. In more detail, as shown in a timing chart ofFIG. 7, a ZrO2-based film having a predetermined film thickness is formed by performing, repeatedly and a plurality of times, a cycle of ZrO2film forming operation via the ALD method, herein the cycle of ZrO2film forming operation includes a step S11for supplying the Zr source gas to the processing chamber1to be adsorbed on the first TiO2film, a step S12for purging the inside of the processing chamber1by using a purge gas, a step S13for supplying a oxidizing agent gas, for example, an O3gas, to the processing chamber1to oxidize the Zr source gas, and a step S14for purging the inside of the processing chamber1with the purge gas. Also, as described above, the ZrO2-based film may be doped with the Al, Si, or the like, or may have the ZAZ structure and the LAZO structure, and in this case, following operation may be performed. First, when the ZrO2-based film is doped with the Al, Si, or the like, a step of supplying a material of the element may be inserted in the cycle of the steps S11through S14, by the number of times according to the doped amount. In a case where the ZAZ structure is used, an Al compound supply mechanism is additionally provided, and then, a ZrO2film of a predetermined film thickness is formed by using the ALD operation for a predetermined times, an Al2O5film is formed by the same ALD operation, and additionally, a ZrO2film is formed by the ALD method. Also, in a case where the LAZO structure is used, the Al compound supply mechanism is additionally provided as described above, and then, a Zr source gas supplying step, an oxidizing step, an Ar source gas supplying step, and an oxidizing step are alternately and repeatedly performed.

In the step S11, the Zr source storage container20of the Zr source gas supply mechanism15supplies the Zr compound that is the Zr source, the vaporizer22vaporizes the Zr compound to generate the Zr source gas, and the Zr source gas is supplied to the processing chamber1for a time period of T1from the gas ejection holes24avia the Zr source gas pipe23and the Zr source gas diffusion nozzle24. Accordingly, the Zr source gas is adsorbed on the wafer W.

The time period T1of the step S11may be, for example, about 0.1 to 1800 sec. In addition, a flow rate of the Zr source may be, for example, about 0.01 to 10 ml/min (ccm). Also, a pressure in the processing chamber1may be, for example, about 0.3 to 66650 Pa.

The step S13for supplying the oxidizing agent, and the steps S12and S14for purging are performed in the same manner as the step S3for supplying the oxidizing agent and the purging steps S2and S4when forming the first TiO2film. Time periods T13, T12, and T14are the same as T3, T2, and T4.

The annealing process is performed for a predetermined time after finishing the forming of the ZrO2-based film, in a state where the pressure in the processing chamber1becomes a decompression state of a predetermined pressure while introducing a predetermined atmospheric gas to the processing chamber1and the heating unit40heats the processing chamber1to a temperature of about 300 to 600° C., as described above. If the annealing process is performed under an inert environment, the N2gas, i.e., may be introduced to the processing chamber1from the purge gas supply source31. If the annealing process is performed under an oxidizing environment, the oxidizing agent may be introduced to the processing chamber1from the oxidizing agent supply source17or an O2gas may be introduced from O2gas introduction mechanism which is additionally provided. Also, if the annealing process is performed under a reduction environment, a mechanism for introducing a reducing gas such as an H2gas may be additionally provided.

4. Process of Forming the Second TiO2Film

Like the first TiO2film, the second TiO2film can be formed by using the Ti source gas formed of the Ti compound and the oxidizing agent, according to the ALD method shown in the timing chart ofFIG. 6. Also, as described above, the second TiO2film can be doped with the Al, Si, Ta, Nb, and the like, and in this case, a step of supplying a material of the element by a number of times according to a doped amount may be inserted in the repeated cycle.

As described above, the first and second TiO2films are formed by using the Ti source gas and the oxidizing agent via the ALD method, and the ZrO2-based film is formed by using the Zr source gas and the oxidizing gas via the ALD method, and thus, a film having less impurities and defects may be obtained under a relatively low temperature. In particular, in a case where a compound containing the cyclopentadienyl ring is used as the Ti source gas and the Zr source gas, an side opposite to the cyclopentadienyl ring becomes an adsorption site, and thereby performing the adsorbing and arranging regularly and obtaining a dense film having less impurities and defects.

<Experimental Result for Identifying Effects of the Present Invention>

Next, experimental results for identifying the effects of the present invention will be described below.

Here, on a TiN film as a lower electrode, a first TiO2film was formed to a thickness of about 1 nm, a ZrO2film was formed on the first TiO2film to a thickness of about 5 nm, and then, an annealing was performed at a temperature of about 500° C. for about 10 minutes under an N2gas environment, and a second TiO2film was formed on the ZrO2film to a thickness of about 5 nm, thereby forming a dielectric film having a total thickness of about 11 nm. Then, a TiN film as an upper electrode was formed on the second TiO2film to manufacture a flat capacitor sample.

The first and second TiO2films were formed by using an MCPDTMT as the Ti source and the O3gas as the oxidizing agent in the ALD method having the sequences shown in the timing chart ofFIG. 6by the film forming apparatus100shown inFIG. 4. Also, the ZrO2film was formed by using a CPDTMZ as the Zr source and the O3gas as the oxidizing agent in the ALD method having the sequences shown in the timing chart ofFIG. 7by the film forming apparatus shown inFIG. 4.

With respect to the sample obtained through the above processes, a CET and a leakage current (J+1V) when Vg is 1V were measured, and the CET was about 0.437 nm and J+1V was about 1.6×10−6A/cm2that result in good values.

The present invention may be variously modified without limiting to the above embodiments. For example, in the above embodiment, the first and second TiO2films and the ZrO2-based film are formed by using the ALD method; however, the present invention is not limited thereto, and the above films may be formed by using the CVD method. Also, the forming of the first and second TiO2films and the ZrO2-based film are formed by a batch-type film forming apparatus, in which the film forming operations are performed in a lump with respect to a plurality of wafers W loaded therein; however, the present invention is not limited thereto, and may be applied to a single-wafer type film forming apparatus which performs the film forming operation on one wafer at a time.

According to the present invention, the first TiO2film is formed on the lower electrode for interface control, and thus, the leakage current to the lower electrode may be restrained. Also, after forming the ZrO2-based film on the first TiO2film, the annealing process for crystallizing the ZrO2is performed, and thus, the ZrO2in the ZrO2-based film can be crystallized. Thus, the second TiO2film formed on the ZrO2-based film and serving as a capacity film can be grown to have the rutile structure. Accordingly, the dielectric constant of the second TiO2film is increased, and the leakage current to the upper electrode can be also restrained. As such, the high dielectric constant property and the low leakage current can be achieved compatibly. Also, the TiN film that is conventionally used can be used as the electrode material, and thus, a unique electrode material or a base is not necessary, and there is no difficulty in fabricating the capacitor.