US20080057224A1

US20080057224A1 - Method of forming a thin film and methods of manufacturing a gate structure and a capacitor using same

Info

Publication number: US20080057224A1
Application number: US11/790,445
Authority: US
Inventors: Youn-Joung Cho; Jung-Ho Lee; Jun-Hyun Cho; Seung-min Ryu; Kyoo-chul Cho; Jung-Sik Choi
Original assignee: Individual
Current assignee: Samsung Electronics Co Ltd
Priority date: 2006-08-30
Filing date: 2007-04-25
Publication date: 2008-03-06
Also published as: KR20080020114A; KR100829608B1

Abstract

A method of manufacturing a thin film includes providing a metal organic precursor onto a substrate where the metal organic precursor is heated to a temperature of about 60° C. to about 95° C. and has a saturated vapor pressure of about 1 Torr to about 5 Torr. An oxidizing agent including oxygen for oxidizing the metal organic precursor is provided onto the substrate. The metal organic precursor and the oxidizing agent are chemically reacted to form the thin film including metal oxide. The thin film is easily available in a gate insulation layer of a gate structure, a dielectric layer of a capacitor, and similar circuit components.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
Example embodiments of the present invention relate to a method of forming a thin film utilizing a metal organic precursor and methods of manufacturing a gate structure and a capacitor using the thin film method.
This U.S. non-provisional patent application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 2006-0083075 filed on Aug. 30, 2006, the entire contents of which are hereby incorporated by reference.
2. Discussion of Related Art
Thin films having a high dielectric constant have been used to form gate insulation layers of a metal oxide semiconductor (MOS) transistor, dielectric layers of a capacitor in a semiconductor device and dielectric layers of a flash memory device. When the film is formed using the material having the high dielectric constant, the film may have a thin equivalent oxide thickness (EOT). Additionally, leakage current generated between a gate electrode and a channel layer or between a lower electrode and an upper electrode may be sufficiently reduced, and a coupling ratio of a flash memory device may be improved. Examples of the material having the high dielectric constant may include tantalum oxide, yttrium oxide, hafnium oxide, zirconium oxide, niobium oxide, barium titanium oxide, strontium titanium oxide, etc.
The hafnium oxide layer may be formed using a hafnium precursor and an oxidant where the hafnium precursor may include tetrakis-ethyl-methyl-amino hafnium (TEMAH, Hf(NC2H5CH3)4), hafnium-tetrakis butoxide [HTTB, Hf(OC4H9)4], etc. When TEMAH is used as the hafnium precursor, it is heated in a canister to a temperature of about 90° C. into a gaseous state and a saturated vapor pressure in the canister maintains a low value of at most about 1 Torr. When TEMAH has a low saturated vapor pressure, delivering the hafnium precursor into a process chamber to form the hafnium oxide layer requires additional time. This additional delivery time reduces the throughput of a semiconductor manufacturing process. Further, TEMAH may deteriorate when it is heated to a temperature above about 90° C. Thus, raising the saturated vapor pressure of the hafnium precursor has its limitation.
Accordingly, a novel metal organic precursor and a method of forming a metal oxide layer using the novel metal organic precursor are needed to manufacture a metal oxide layer having substantially the same dielectric characteristics as those of a conventional metal oxide layer and to manufacture a metal oxide layer more productively. In addition, the metal organic precursor used is required to have a saturated vapor pressure above about 1 Torr at a temperature below about 90° C. and to have a good reactivity with an oxidizing agent.

SUMMARY OF THE INVENTION

Example embodiments of the present invention are directed to a method of forming a thin film including metal oxide. The thin film has electrical characteristics similar to those of a hafnium oxide layer formed using TEMAH and increases the throughput of a semiconductor manufacturing process. The thin film method includes providing a metal organic precursor onto a substrate. The metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated to a temperature of about 60° C. to about 90° C. An oxidizing agent that includes oxygen is provided onto the substrate and is configured to oxidize the metal organic precursor. The metal organic precursor is chemically reacted with the oxidizing agent to form the thin film including a metal oxide on the substrate.
According to one aspect of the present invention, there is provided a method of forming a thin film. In the method of forming the thin film, a metal organic precursor represented by a formula (1) is provided onto a substrate. The metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated upto a temperature of about 60° C. to about 90° C. An oxidizing agent including oxygen for oxidizing the metal organic precursor is provided onto the substrate. The thin film including metal oxide is formed on the substrate by chemically reacting the metal organic precursor with the oxidizing agent.
According to another aspect of the present invention, there is provided a method of forming a thin film. In the method of forming the thin film, a first reactive material including a metal organic precursor represented by a formula (1) is provided onto a substrate. The metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated upto a temperature of about 60° C. to about 95° C. A first portion of the first reactive material is chemically adsorbed onto the substrate and a second portion of the first reactive material is physically adsorbed onto the substrate. An oxidizing agent including oxygen is provided onto the substrate. A first solid material including a metal oxide is formed on the substrate by chemically reacting the first portion of the first reactive material with the oxidizing agent. A second reactive material including an aluminum organic precursor is provided onto the first solid material. A first portion of the second reactive material is chemically adsorbed onto the first solid material and a second portion of the second reactive material is physically absorbed onto the first solid material. An oxidizing agent is provided onto the first solid material. A second solid material including aluminum oxide is formed on the first solid material by chemically reacting the first portion of the second reactive material with the oxidizing agent. As a result, a solid material including metal-aluminum oxide is completed.
R3-N=M(N(R1)(R2))2 (1)
Here, R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents zirconium or hafnium.
According to still another aspect of the present invention, there is provided a method of manufacturing a gate structure of a semiconductor device. In the method of manufacturing a gate structure of a semiconductor device, a metal organic precursor represented by a formula (2) is provided on a substrate. The metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated upto a temperature of about 60° C. to about 95° C. in a canister. An oxidizing agent including oxygen for oxidizing the metal organic precursor is provided onto the substrate. A gate insulation layer including metal oxide is formed on the substrate by chemically reacting the metal organic precursor with the oxidizing agent. A conductive layer is formed on the gate insulation layer. A gate structure including and a gate insulation layer pattern and a gate conductive pattern is formed on the substrate by patterning the conductive layer and the gate insulation layer.
According to still another aspect of the present invention, there is provided a method of manufacturing a capacitor of a semiconductor device. In the method of manufacturing the capacitor of the semiconductor device, a lower electrode is formed on a substrate. A metal organic precursor represented by a formula (2) is provided onto the substrate. The metal organic precursor is heated upto a temperature of about 60° C. to about 95° C., and has a saturated vapor pressure of about 1 Torr to about 5 Torr. An oxidizing agent including oxygen for oxidizing the metal organic precursor is provided onto the substrate. A dielectric layer including a metal oxide is formed on the lower electrode by chemically reacting the metal organic precursor with the oxidizing agent. An upper electrode is formed on the dielectric layer. As a result, a capacitor including the lower electrode, a dielectric layer that includes the metal oxide and the upper electrode is formed on the substrate.
R3-N=M(N(R1)(R2))2 (2)
Here, R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents zirconium or hafnium.
In an example embodiment of the present invention, the metal organic precursor in a gaseous state may be formed by heating a metal organic precursor in a liquid state at a temperature of about 75° C. to about 85° C. in a canister, and the metal organic precursor in the gaseous state may have a saturated vapor pressure of about 3 Torr to about 5 Torr.
In an example embodiment of the present invention, the metal organic precursor may be provided onto the substrate with a carrier gas. Examples of the carrier gas may include argon gas, nitrogen gas, helium gas, etc.
In an example embodiment of the present invention, a first purge process using a purge gas may be further performed on the substrate after the metal organic precursor is provided onto the substrate, and a second purge process using the purge gas may be further performed on the substrate after the oxidizing agent is provided onto the substrate. The thin film may be formed at a temperature of about 250° C. to about 400° C. and under a pressure of about 0.5 Torr to about 3.0 Torr.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 5 are cross-sectional views illustrating a method of forming a thin film in accordance with embodiments of the present invention;

FIG. 6 is a flow chart illustrating a method of forming a thin film in accordance with embodiments of the present invention;

FIGS. 7-10 are cross-sectional views illustrating methods of manufacturing a gate structure in accordance with embodiments of the present invention;

FIGS. 11-14 are cross-sectional views illustrating methods of manufacturing a capacitor in accordance with embodiments of the present invention;

FIG. 15 is a graph illustrating changes in saturated vapor pressures of hafnium precursors according to a change in temperature;

FIG. 16 is a graph illustrating a change in a saturated vapor pressure of zirconium precursor according to a change in temperature;

FIG. 17 is a graph illustrating results of thermo-gravimetric analysis (TGA) in TEMAH and tertiary-butyl-imido bis-metyl-ethyl-amino zirconium;

FIG. 18 is a graph illustrating a leakage current of a capacitor having a hafnium oxide layer as a dielectric layer in accordance with an embodiment of the present invention;

FIG. 19 is a graph illustrating a leakage current of a capacitor formed using a zirconium-aluminum oxide layer in accordance with an embodiment of the present invention; and

FIG. 20 is a graph illustrating step coverage of zirconium oxide layers in accordance with an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements throughout.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Furthermore, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature in relation to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may otherwise be oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Method of Forming a Thin Film

FIGS. 1 to 5 are cross-sectional views illustrating a method for forming a thin film on a substrate 10 in a process chamber 50. When an internal temperature of the process chamber 50 is under about 250° C., a reactivity of a metal organic precursor in a gaseous state may be disadvantageously low in subsequent processes. When the internal temperature of the process chamber 50 is over about 450° C., the thin film formed on the substrate 10 may be disadvantageously crystallized and deposited with characteristics of chemical vapor deposition (CVD). Therefore, the internal temperature of the process chamber 50 should be in the range of about 250° C. to about 450° C. and preferably in the range of about 250° C. to about 400° C. By way of example, a thin film formed in the process chamber 50 at a temperature of about 300° C. exhibits good characteristics of atomic layer deposition (ALD).
When an internal pressure of the process chamber 50 is under about 0.5 Torr, reactivity of the metal organic precursor in subsequent processes may be disadvantageously low. However, when the internal pressure of the process chamber 50 is over about 0.3 Torr, a process for forming the thin film is not easily controlled. Therefore, the internal pressure of the process chamber 50 should be in the range of about 0.5 Torr to 3.0 Torr and preferably in the range of about 0.05 Torr to about 2.0 Torr. By way of example, a thin film formed under an internal pressure of the process chamber 50 at about 1.0 Torr exhibits good characteristics of an ALD.
A metal organic precursor represented by formula (1) (identified below) is provided into the process chamber 50 at the above-mentioned temperature and pressure. The metal organic precursor may be provided into the process chamber 50 using a canister or a liquid delivery system for about 0.5 seconds to 5 seconds. For example, the metal organic precursor is provided into the process chamber 50 and vaporized at a temperature of about 100° C. to about 150° C. for approximately 1 second. As a result, a first portion 12 of the metal organic precursor may be chemically adsorbed (chemisorbed) onto the substrate 10, and a second portion 14 (i.e., a remaining portion of the metal organic precursor excluding the first portion 12) may be physically adsorbed (physisorbed) onto the first portion 12 to have a weak bonding, or the second portion 14 may be floated in the process chamber 50. Some portions of the metal organic precursor chemisorbed on the substrate 10 may be decomposed by internal heat of the process chamber 50. Therefore, a core metal of the metal organic precursor may be chemisorbed on the substrate 10 and some ligands coupled with the core metal may be separated from the core metal. The metal organic precursor is represented by:
R3-N=M(N(R1)(R2))2 (1)
where R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents titanium, zirconium or hafnium. For example, R1, R2 and R3 may independently include a methyl group, an ethyl group, a prophyl group, a tertiary butyl group, etc. The metal organic precursor represented by formula (1) may include tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2] or tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2]. The metal organic precursor may be in a liquid state at room temperature and may be vaporized into a gaseous state at a temperature of about 60° C. to about 95° C., thereby generating inert gas bubbles. When the metal organic precursor is vaporized in a canister, the vaporized precursor may have a saturated vapor pressure of about 1 Torr to 5 Torr. In other words, the metal organic precursor may be generated until the metal organic precursor in the gaseous state becomes saturated.
When the metal organic precursor in the liquid state represented by formula (1) is heated to a temperature of about 65° C. to about 75° C. in the canister, a vaporized metal organic precursor may have a saturated vapor pressure of about 1 to about 3 Torr. The metal organic precursor may include, for example, a hafnium precursor or a zirconium precursor. When the metal organic precursor in the liquid state is heated to about 85° C. to about 95° C., it is vaporized and has a saturated vapor pressure of about 3 to about 5 Torr. Thus, the metal organic precursor represented by formula (1) has a higher saturated vapor pressure than that of a conventional hafnium precursor such as TEMAH, and the metal organic precursor may have good reactivity with an oxidizing agent. The time required for providing the metal organic precursor into a process chamber to form a thin film may be reduced. Additionally, less of a carrier gas provided along with the vaporized metal organic precursor may be consumed and the amount of metal organic precursor provided into the process chamber may also be reduced. In this manner, when the metal organic precursor represented by formula (1) is employed in a thin film, a thin film having a relatively higher dielectric constant and a relatively lower leakage current than conventional thin films may be manufactured. Consequently, the throughput of a semiconductor manufacturing process may be increased.
Referring to FIG. 2 where a zirconium precursor is used as the metal organic precursor, an inert gas is used as a purge gas and provided into process chamber 50 for about 1 to about 30 seconds. In this example, the inert gas is included in the chamber for about 30 seconds and the inert gas may include argon gas, nitrogen gas, etc. By providing the purge gas into the process chamber 50, the second portion 14 which is physisorbed on the first portion 12 of the metal organic precursor or floated in the chamber 50 may be removed. As a result, zirconium precursor molecules 12 a remain as the first portion 12 on the substrate 10.
Instead of providing the purge gas and maintaining the process chamber 50 in a vacuum condition for about 1 to about 30 seconds, the second portion 14 physisorbed on the first portion 12 of metal organic precursor or floated in the process chamber 50 may be removed. Alternatively, by providing the purge gas into process chamber 50 and maintaining the chamber in a vacuum condition, the second portion 14 physisorbed to the first portion 12 of the metal organic precursor or floated in the process chamber 50 may be removed.
Referring to FIG. 3, an oxidizing agent 16 including oxygen is provided into the chamber 50. Examples of the oxidizing agent 16 may include ozone (O3), oxygen (O2), water (H2O), plasma oxygen, remote plasma oxygen, etc., which may be used alone or in combination. The oxidizing agent 16 is provided into the process chamber 50 for about 0.5 to about 5.0 seconds. By way of example, ozone (O3) may be used as the oxidizing agent 16 and is provided into the process chamber 50 for about 2.0 seconds. The oxidizing agent 16 chemically reacts with the zirconium precursor molecules 12 a which is the first portion 12 of a reactant chemisorbed on substrate 10 to oxidize the zirconium precursor molecules 12 a.
Referring to FIG. 4, a purge gas is provided into the process chamber 50 where the type of purge gas and time in the chamber 50 is substantially the same as described with reference to FIG. 2. By providing the purge gas into the process chamber 50, the oxidizing agent 16 that remains chemically unreacted may be removed. In this manner, a solid material 18 including zirconium oxide may be formed on the substrate 10.
FIG. 5 illustrates a substrate 10 on which the processes described with reference to FIGS. 1 to 4 are performed at least once. As a result, a thin film 20 having a multi-layer structure of a solid material 18 may be formed on the substrate 10 where the thin film 20 includes zirconium oxide. A thickness of the thin film 20 may be controlled according to repetition times of the processes. The thin film 20 may include zirconium oxide or hafnium oxide formed using a zirconium precursor or a hafnium precursor on the substrate 10. The zirconium precursor or the hafnium precursor has a saturated vapor pressure higher than that of a conventional precursor so that the thin film 20 may have a relatively higher dielectric constant and a lower leakage current. In an alternative embodiment, instead of an ALD process in which the zirconium precursor and the oxidizing agent are used, the thin film 20 may be formed by a CVD process in which the zirconium precursor and the oxidizing agent are simultaneously provided into the process chamber 50.
When the thin film 20 including the solid material 18 is formed on the substrate 10, the zirconium precursor in the gaseous state and the oxidizing agent are introduced simultaneously to the substrate 10 in the process chamber 50. The zirconium precursor and the oxidizing agent chemically react with each other over the substrate 10 to form zirconium oxide. The zirconium oxide is chemisorbed onto the surface of the substrate 10 to form the solid material 18. The zirconium oxide is successively chemisorbed onto the solid material 18 to form the thin film 20 where the thickness of the thin film 20 is controlled by the CVD duration.
FIG. 6 is a flow chart illustrating a method of forming a thin film in accordance with the present invention where a substrate is disposed in a chamber in step S110. The internal temperature of the chamber is in the range of about 250° C. to about 450° C. and preferably at 300° C. A first reactive material is provided onto the substrate in step S120 where the first reactive material is a metal organic precursor including a hafnium precursor and a zirconium precursor. For example, the hafnium precursor includes tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2], and the zirconium precursor includes tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2]. Preferably, the first reactive material is provided onto the substrate for about 0.5 to about 3 seconds and specifically for about 1 second by a liquid delivery system. When tertiary-butyl-imido bis-metyl-ethyl-amino zirconium is provided onto the substrate, a first portion of the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium may be chemisorbed onto the substrate and a second portion of the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium may be physisorbed onto the substrate.
In step S130, argon gas is provided onto the substrate to perform a first purge process on the substrate. Preferably, argon gas is provided onto the substrate for about 0.5 to about 3 seconds and specifically for 1 second. When argon gas is provided onto the substrate, the second portion of the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium may be removed. That is, when argon gas is provided onto the substrate, a hydrocarbon radical contained in the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium may be taken from the substrate. Although argon gas is provided onto the substrate, zirconium contained in the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium may still remain chemisorbed on the substrate. By maintaining the chamber in a vacuum condition for about 2 to about 3 seconds, the hydrocarbon radical may be taken-off from the substrate.
An oxidizing agent including oxygen is provided onto the substrate in step S140. Examples of an oxidizing agent include ozone (O3), water vapor (H2O), hydrogen peroxide (H2O2), methyl alcohol (CH3OH), ethyl alcohol (C2H5OH), etc. which may be used alone or in combination. In an example embodiment of the present invention, ozone is used as the oxidizing agent. Preferably, ozone is provided onto the substrate for about 1 to about 5 seconds and specifically for about 3 seconds. When the oxidizing agent is provided onto the substrate, zirconium chemisorbed on the substrate may be oxidized. As a result, a first solid material containing zirconium oxide is formed on the substrate.
In step S150, a second purge process using argon gas is performed on the substrate. Preferably, argon gas is provided onto the substrate for about 1 to about 5 seconds and specifically for about 3 seconds. When argon gas is provided onto the substrate, an oxidizing agent remaining in the chamber is removed. In this manner, the first solid material including zirconium oxide is formed on the substrate. By repeatedly providing tertiary-butyl-imido bis-metyl-ethyl-amino zirconium, argon gas, an oxidizing agent and argon gas, a zirconium oxide layer including the first solid material may be formed having a predetermined thickness.
In step S160, a second reactive material is provided onto the first solid material formed in step S140. The second reactive material includes an aluminum precursor. Examples of the aluminum precursor may include tri-methyl-aluminum (TMA), tri-ethy-aluminum (TEA), tri-isobuthyl-aluminum, etc. Preferably, the second reactive material is provided onto the first solid material for about 1 second. By providing TEA as the second reactive material onto the first solid material, a first portion of the TEA may be chemisorbed onto the first solid material and a second portion of the TEA may be physisorbed onto the first solid material.
A third purge process using argon gas is performed on the substrate in step S170. Preferably, argon gas is provided onto the first solid material for about 1 second as a purge gas and the second portion of the TEA physisorbed on the first solid material may be removed. An oxidizing agent is provided onto the first solid material in step S180. The oxidizing agent may be substantially the same as that described in step S140. Ozone (O3) as the oxidizing agent may be provided onto the first solid material for about 3 seconds. When the oxidizing agent is provided onto the first solid material, aluminum chemisorbed on the first solid material is oxidized. As a result, a second solid material including aluminum oxide may be formed on the first solid material.
In step S190, a fourth purge process using argon gas is performed on the substrate. Preferably, argon gas as a purge gas is provided onto the second solid material for about 3 seconds and the oxidizing agent remaining in the chamber may be removed. Accordingly, the second solid material including aluminum oxide is formed on the first solid material. By repeatedly providing TEA, argon gas, an oxidizing agent and argon gas, an aluminum oxide layer including the second solid material having a predetermined thickness may be formed. Here, a cycle is defined by the number of processes performed that provide a precursor, argon gas, an oxidizing agent and argon gas to form a metal oxide layer. By controlling the number of cycles for forming the first solid material that includes zirconium oxide using the zirconium precursor and cycles for forming the second solid material that includes aluminum oxide using the aluminum precursor, a composite metal oxide layer including zirconium-aluminum oxide that has a desired composition ratio of zirconium and aluminum may be formed in step S200. Alternatively, instead of the zirconium precursor, a hafnium precursor may be used. By controlling the number of cycles for forming the first solid material that includes hafnium oxide using the hafnium precursor and the number of cycles for forming the second solid material that includes aluminum oxide using the aluminum precursor, a composite metal oxide layer including hafnium-aluminum oxide that has a desired composition ratio of hafnium and aluminum may be formed.

Method of Manufacturing a Gate Structure

FIGS. 7-10 are cross-sectional views illustrating methods of manufacturing a gate structure in accordance with example embodiments of the present invention. Referring to FIG. 7, a conventional isolation process is performed to define an active region and a field region 102 in a substrate 100. Here, examples of the substrate 100 may include silicon substrate, silicon-on-insulator (SOI) substrate, etc. A gate insulation layer 104 including, for example, a metal oxide is formed on the substrate 100 which has a relatively low EOT and sufficiently reduces a leakage current between a gate electrode and a channel region. In particular, the gate insulation layer 104 may include hafnium oxide or zirconium oxide, and may be formed by an ALD process that is substantially the same as that shown for forming the thin film in FIGS. 1 to 5. Alternatively, the gate insulation layer 104 may include zirconium-aluminum oxide and may be formed by an ALD process that is substantially the same as that for forming the thin film as shown in FIG. 6. A metal organic precursor used in the ALD process may be represented by:
R3-N=M(N(R1)(R2))2 (2)
where R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents titanium, zirconium or hafnium. R1, R2 and R3 may, for example, independently include a methyl group, an ethyl group, a prophyl group, and a tertiary butyl group, etc. The metal organic precursor represented by formula (2) may include tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2] or tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2]. The metal organic precursor may be in a liquid state at room temperature and may be vaporized into a gaseous state at a temperature of about 60° C. to about 95° C. When the metal organic precursor is vaporized in a canister, the vaporized metal organic precursor may have a saturated vapor pressure of about 1 Torr to 5 Torr. Methods for forming the gate insulation layer 104 are substantially the same as those illustrated with reference to FIGS. 1 to 5.
In an example embodiment of the present invention, the gate insulation layer 104 including zirconium oxide may be formed on the substrate 100 by performing an ALD process using a hafnium precursor or a zirconium precursor. A silicon oxide layer having a thickness of about 5 Å may also be formed on the gate insulation layer 104. The silicon oxide layer may be formed in-situ after the gate insulation layer 104 including zirconium oxide is formed.
Referring to FIG. 8, a gate conductive layer 110 is formed on the gate insulation layer 104. The gate conductive layer 110 may be formed to have a multi-layered structure, i.e., a poly-crystalline silicon layer 106 and a metal silicide layer such as a tungsten silicide are sequentially stacked. A capping insulation layer 112 including silicon oxide may be formed on the gate conductive layer 110.
Referring to FIG. 9, the capping insulation layer 112, the gate conductive layer 110 and the gate insulation layer 104 on the substrate 100 are sequentially patterned by a photolithography process. As a result, a gate structure 115 including a gate insulation layer pattern 104 a, a gate conductive pattern 110 a and a capping insulation layer pattern 112 a is formed on the substrate 100. FIG. 10 illustrates a source/drain region 120 formed at an upper portion of the substrate 100 adjacent to gate structure 115. The source/drain region 120 may be formed before forming the gate insulation layer 104 or after forming a spacer 114 on the gate structure 115. The gate insulation layer pattern 104 a including hafnium oxide or zirconium oxide that has a high dielectric constant may have a relatively low EOT which sufficiently reduces a leakage current between a gate conductive pattern 106 a and the substrate 100. When the gate insulation layer 104 is formed using a metal organic precursor represented by formula (2), a process time for manufacturing the gate insulation layer 104 may be reduced so that the gate structure 115 formed faster.

Method of Manufacturing a Capacitor

FIGS. 11 to 14 are cross-sectional views illustrating methods of manufacturing a capacitor in accordance with example embodiments of the present invention. FIG. 11 illustrates a substrate 100 having an insulating interlayer 124 including a contact hole 126 that exposes a contact plug 122. A conductive layer 132 for a lower electrode is continuously formed on an inner sidewall and a bottom portion of a contact hole 126 through the insulating interlayer 124 to form an electrical connection with a contact plug 122. When a semiconductor device such as a dynamic random access memory (DRAM) is formed on the substrate 100, a semiconductor structure including a gate 115 having a spacer 114, a bit line (not shown), the contact plug 122, etc., may be formed on the substrate 100. The conductive layer 132 may be formed using a material such as polycrystalline silicon, titanium nitride, tantalum nitride, tungsten nitride, ruthenium, etc. which may be used alone or in a combination.
FIG. 12 illustrates a lower electrode 140 formed to electrically connect to the contact plug 122. After a sacrificial layer (not shown) is formed on the conductive layer 132, the sacrificial layer is removed until an upper face of the conductive layer 132 is exposed. The conductive layer 132 on the insulating interlayer 124 is removed to form a lower electrode 140 on the inner sidewall and bottom of the contact hole 126. The sacrificial layer remaining in the contact hole 126 and the insulating interlayer 124 is removed to complete the lower electrode 140. The lower electrode 140 may have a cylindrical shape in which a width of an upper portion is wider than that of a lower portion of the lower electrode 140.
Referring to FIG. 13, a dielectric layer 150 is formed on the lower electrode 140 having a relatively thin EOT and a relatively high dielectric constant which may sufficiently reduce a leakage current between the lower electrode 140 and an upper electrode. In an example embodiment, the dielectric layer 150 a is formed using a thin film including a metal oxide. For example, the thin film may include hafnium oxide or zirconium oxide and may be formed by an ALD process that is substantially the same as that for forming the thin film as shown in FIGS. 1 to 5. Alternatively, the thin film may include zirconium-aluminum oxide, and may be formed by an ALD process that is substantially the same as that for forming the thin film as referenced in FIG. 6. A metal organic precursor may include tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2] or tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2]. The dielectric layer 150 including hafnium oxide may be formed on the lower electrode 140 by an ALD process using the metal organic precursor.
Referring to FIG. 14, after the dielectric layer 150 is formed, it is thermally treated to remove a contaminant and restore oxygen vacancies. The heat treatment process may include an ultraviolet ozone (UV-O3) treatment, a plasma treatment, etc. An upper electrode 160 may be formed on the dielectric layer 150 using polycrystalline silicon, titanium nitride, tantalum nitride, tungsten nitride, ruthenium, etc. which may be used alone or in combination. Thus, a capacitor that includes the lower electrode 140, the dielectric layer 150 having hafnium oxide, and the upper electrode 160 is formed on the substrate 100. In another embodiment, a thin solid film including hafnium oxide that has a high dielectric constant is formed as dielectric layer 150 having a relatively low EOT
Saturated vapor pressures of tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2] and tetrakis-ethyl-methyl-amino hafnium [TEMAH, Hf(NC2H5CH3)4] that are hafnium precursors of a thin film including hafnium oxide were respectively measured. The measurement was performed by measuring changes in saturated vapor pressures according to different temperatures after the hafnium precursors were contained in a 10 L canister and the hafnium precursors were heated into a gaseous phase. Results of measured changes in an inner pressure of the canister at a temperature of about 20° C. to about 90° C. are illustrated in the graph of FIG. 15. Here, the saturated vapor pressures of the hafnium precursors are substantially the same as the inner pressure of the canister. As shown in the graph, tertiary-butyl-imido bis-methyl-ethyl-amino hafnium has a vapor pressure of about 1 Torr when the tertiary-butyl-imido bis-methyl-ethyl-amino hafnium is heated to a temperature of about 72° C., thus, the inner pressure of the canister is about 1 Torr. Additionally, tertiary-butyl-imido bis-methyl-ethyl-amino hafnium has a vapor pressure of about 3 Torr when the tertiary-butyl-imido bis-methyl-ethyl-amino hafnium is heated to a temperature of about 90° C., thus the inner pressure of the canister is about 3 Torr. However, TEMAH (i.e., a conventional hafnium precursor) has a vapor pressure of about 0.4 Torr when the TEMAH is heated to a temperature of about 72° C., thus the inner pressure of the canister is about 0.4 Torr. Additionally, TEMAH has a vapor pressure of about 1 Torr when the TEMAH is heated to a temperature of about 90° C. and the inner pressure of the canister is about 1 Torr. As a result, when the thin film including hafnium oxide is formed, tertiary-butyl-imido bis-methyl-ethyl-amino hafnium has a vapor pressure that is about twice as high as that of TEMAH. Therefore, when the thin film is formed using tertiary-butyl-imido bis-methyl-ethyl-amino hafnium, a process time for forming the thin film may be reduced and consequently the throughput of a semiconductor manufacturing process may be increased.
A change in the saturated vapor pressure of tertiary-butyl-imido bis-metyl-ethyl-amino zirconium as a zirconium precursor was measured according to different temperatures by substantially the same method as that illustrated with reference to FIG. 15, the results of which are illustrated in FIG. 16. A saturated vapor pressure of the zirconium precursor is substantially the same as an inner pressure of a canister. As shown in the graph, tertiary-butyl-imido bis-metyl-ethyl-amino zirconium as a zirconium precursor has a vapor pressure of about 1 Torr when the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium is heated to a temperature of about 72° C., thus, the inner pressure of the canister is about 1 Torr. Additionally, tertiary-butyl-imido bis-metyl-ethyl-amino zirconium has a vapor pressure of about 2.7 Torr when the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium is heated to a temperature of about 90° C., thus the inner pressure of the canister is about 3 Torr. Therefore, when the thin film is formed using tertiary-butyl-imido bis-metyl-ethyl-amino zirconium, a process time for forming the thin film may be reduced and consequently the throughput of a semiconductor manufacturing process may be increased.
FIG. 17 is a graph illustrating results of a thermo-gravimetric analysis (TGA) in TEMAH and tertiary-butyl-imido bis-metyl-ethyl-amino zirconium. The TGA is an analysis that registers a weight change in a sample according to time and temperature while increasing a temperature of the sample at a constant speed or isothermally maintaining the temperature of the sample. As a result, a weight increase or a weight decrease according to pyrolysis, sublimation, vaporization and oxidation may be analyzed by a thermogram. While heating tertiary-butyl-imido bis-methyl-ethyl-amino hafnium and tertiary-butyl-imido bis-metyl-ethyl-amino zirconium that were metal organic precursors from a room temperature to about 400° C. by 5° C./min, weight loss of each precursor was measured. At a temperature in a range of about 130° C. to about 220° C., the weight loss of the each precursor abruptly occurred. That is, tertiary-butyl-imido bis-methyl-ethyl-amino hafnium, tertiary-butyl-imido bis-metyl-ethyl-amino zirconium and TEMAH were vaporized from a liquid phase to a gaseous phase. Based on the above analysis, tertiary-butyl-imido bis-methyl-ethyl-amino hafnium and tertiary-butyl-imido bis-metyl-ethyl-amino zirconium were confirmed as proper metal organic precursors for an ALD process like TEMAH.
FIG. 18 is a graph illustrating a leakage current of a capacitor having the hafnium oxide layer as a dielectric layer in accordance with an embodiment of the present invention. A leakage current of a cell capacitor including a hafnium oxide was measured after a hafnium oxide layer employed in the cell capacitor was formed by an ALD process using tertiary-butyl-imido bis-methyl-ethyl-amino hafnium. The hafnium oxide layer had a thickness of about 13.7 Å. The cell capacitor including the hafnium oxide layer formed using tertiary-butyl-imido bis-methyl-ethyl-amino hafnium indicated a relatively low leakage current of about 1.00 E-15 A/cm2 at a voltage of about 0.5V. Additionally, the cell capacitor indicated a relatively low leakage current of about 1.00 E-13 A/cm2 at a voltage of about 1.3V. The cell capacitor including the hafnium oxide layer was confirmed to have good leakage current and cell capacitance characteristics. Thus, tertiary-butyl-imido bis-methyl-ethyl-amino hafnium precursor was confirmed to be available in a semiconductor manufacturing apparatus.
FIG. 19 is a graph illustrating a leakage current of a capacitor formed using a zirconium-aluminum oxide layer in accordance with an embodiment of the present invention. A leakage current of a cell capacitor including a composite metal oxide layer was measured after the composite metal oxide layer employed in the cell capacitor was formed by an ALD process using the tertiary-butyl-imido bis-methyl-ethyl-amino hafnium precursor and a tri-methyl-aluminum (TMA) precursor. The composite metal oxide layer has a stacked structure including a first zirconium oxide (ZrO2) layer of about 70 Å, an aluminum oxide layer (Al2O3) of about 4 Å and a second zirconium oxide (ZrO2) layer of about 40 Å. The cell capacitor including the zirconium-aluminum oxide layer formed using a tertiary-butyl-imido bis-metyl-ethyl-amino zirconium precursor indicated a relatively low leakage current of about 1.00 E-17 A/cm2 at a voltage of about 0.4 V. Additionally, the cell capacitor indicated a leakage current of about 1.00 E-16 A/cm2 at a voltage of about 2.1 V. The cell capacitor including the zirconium-aluminum oxide layer was confirmed to have good leakage current and cell capacitance characteristics. Thus, the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium precursor was confirmed to have good characteristics when the tertiary-butyl-imido bis-metyl-ethyl-amino zirconium precursor may be used in a semiconductor manufacturing apparatus.

Conformality of a Metal Oxide Layer

TABLE 1

Process condition

	Second	Chamber	Canister	Carrier
First Reactant	Reactant	Temperature	Temperature	Gas

(t-	O3	340° C.	80° C.	1000
BuN)Zr(N(Me)(Et))2				sccm
TEMAZ	O3	320° C.	80° C.	1000
				sccm

Zirconium oxide layers were formed on a cylindrical structure having an aspect ratio of about 10:1 by an ALD process according to the process conditions specified in Table 1. Step coverage of the zirconium oxide layers was measured and the results illustrated in FIG. 20. Step coverage is a ratio of a first thickness of the zirconium oxide layer formed on an upper portion of the structure with respect to a second thickness of the zirconium oxide layer formed on a bottom of a hole contained in the structure. FIG. 20 is a graph illustrating step coverages of zirconium oxide layers in accordance with an embodiment of the present invention. A zirconium oxide layer including tertiary-butyl-imido bis-metyl-ethyl-amino zirconium precursor has relatively high step coverage of about 87%, whereas a zirconium oxide layer including tetra-ethyl-methyl-amid zirconium precursor has a relatively low step coverage of about 64%. As a result, tertiary-butyl-imido bis-metyl-ethyl-amino zirconium precursor may be employed in a process for forming a dielectric layer of a cylindrical capacitor.
Accordingly, when a metal organic precursor represented by R3-N=M(N(R1)(R2))2 is used for forming a thin film including metal oxide, the metal organic precursor may have a higher saturated vapor pressure than those of conventional metal organic precursors such as TEMAH or TEMAZ. Additionally, the metal organic precursor may have a high reactivity with an oxidizing agent. Thus, throughput and step coverage in a thin film manufacturing process may be improved. Additionally, a thin film formed using the metal organic precursor may have good leakage current characteristics. Therefore, the thin film may be employed in a gate insulation layer of a gate structure, a dielectric layer of a capacitor, etc., so that the electrical reliability of a semiconductor device may be improved.
Although the present invention has been described in connection with the embodiment of the present invention illustrated in the accompanying drawings, it is not limited thereto. It will be apparent to those skilled in the art that various substitution, modifications and changes may be thereto without departing from the scope and spirit of the invention.

Claims

1. A method of forming a thin film comprising:

providing a metal organic precursor onto a substrate, wherein the metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated to a temperature of about 60° C. to about 90° C.;

providing an oxidizing agent including oxygen onto the substrate, the oxidizing agent configured to oxidize the metal organic precursor; and

forming the thin film including a metal oxide on the substrate by chemically reacting the metal organic precursor with the oxidizing agent.

2. The method of claim 1, wherein providing a metal organic precursor is represented by R3-N=M(N(R1)(R2))2 wherein R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents zirconium or hafnium.

3. The method of claim 1, wherein the metal organic precursor comprises tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2].

4. The method of claim 1, wherein the metal organic precursor comprises tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2].

5. The method of claim 1, wherein the metal organic precursor is in a gaseous state having a saturated vapor pressure of about 3 Torr to about 5 Torr, the precursor formed by heating the precursor in a liquid state at a temperature of about 75° C. to about 85° C. in a canister.

6. The method of claim 1, wherein the metal organic precursor is provided onto the substrate with at least one carrier gas selected from the group consisting essentially of argon gas, nitrogen gas and helium gas.

7. The method of claim 1, further comprising:

performing a first purge process on the substrate using a purge gas after the metal organic precursor is provided onto the substrate, and

performing a second purge process on the substrate using the purge gas after the oxidizing agent is provided onto the substrate.

8. The method of claim 7, wherein the thin film is formed at a temperature of about 250° C. to about 400° C. under a pressure of about 0.5 Torr to about 3.0 Torr.

9. The method of claim 8, wherein the metal organic precursor is provided onto the substrate by a liquid delivery system, the method further comprising vaporizing the metal organic precursor at a temperature of about 100° C. to about 150° C. in the liquid delivery system.

10. A method of forming a thin film including metal-aluminum oxide, the method comprising:

(a) providing a first reactive material including a metal organic precursor onto a substrate, the metal organic precursor having a saturated vapor pressure of about 1 Torr to about 5 Torr when the precursor is heated to a temperature of about 60° C. to about 95° C., the metal organic precursor represented by R3-N=M(N(R1)(R2))2 wherein R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents zirconium or hafnium.

(b) chemically adsorbing a first portion of the first reactive material onto the substrate and physically adsorbing a second portion of the first reactive material onto the substrate;

(c) providing an oxidizing agent including oxygen onto the substrate;

(d) forming a first solid material including a metal oxide on the substrate by chemically reacting the first portion of the first reactive material with the oxidizing agent;

(e) providing a second reactive material including an aluminum organic precursor onto the first solid material;

(f) chemically adsorbing a first portion of the second reactive material onto the first solid material and physically adsorbing a second portion of the second reactive material onto the first solid material;

(g) providing an oxidizing agent onto the first solid material; and

(h) forming a second solid material including aluminum oxide on the first solid material by chemically reacting the first portion of the second reactive material with the oxidizing agent,

11. The method of claim 10, further comprising:

removing the second portion of the first reactive material physically adsorbed on the substrate;

removing a portion of the oxidizing agent, the portion configured not reactive with the first portion of the first reactive material;

removing the second portion of the second reactive material physically adsorbed on the substrate; and

removing a portion of the oxidizing agent, the portion configured not reactive with the first portion of the second reactive material.

12. The method of claim 10, wherein steps (a)-(d) are repeatedly performed at least once, respectively.

13. The method of claim 10, wherein steps (e)-(h) are repeatedly performed at least once.

14. The method of claim 10, wherein steps (a)-(h) are repeatedly performed at least once.

15. The method of claim 10, wherein the metal organic precursor comprises tertiary-butyl-imido bis-methyl-ethyl-amino hafnium [(t-BuN)Hf(N(CH3)(C2H5))2] tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2].

16. The method of claim 10, wherein the metal organic precursor comprises tertiary-butyl-imido bis-metyl-ethyl-amino zirconium [(t-BuN)Zr(N(CH3)(C2H5))2].

17. A method of manufacturing a gate structure of a semiconductor device, the method comprising:

providing a metal organic precursor onto a substrate, wherein the metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated to a temperature of about 60° C. to about 95° C. in a canister, the metal organic precursor represented by R3-N=M(N(R1)(R2))2 where R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents zirconium or hafnium;

providing an oxidizing agent including oxygen onto the substrate, the oxidizing agent configured to oxidize the metal organic precursor;

forming a gate insulation layer including a metal oxide on the substrate by chemically reacting the metal organic precursor with the oxidizing agent provided on the substrate;

forming a conductive layer on the gate insulation layer; and

forming the gate structure including a gate insulation layer pattern and a gate conductive pattern sequentially stacked on the substrate by patterning the conductive layer and the gate insulation layer.

18. A method of manufacturing a capacitor, comprising:

forming a lower electrode on a substrate;

providing a metal organic onto the substrate, wherein the metal organic precursor has a saturated vapor pressure of about 1 Torr to about 5 Torr when the metal organic precursor is heated up to a temperature of about 60° C. to about 95° C., the metal organic precursor represented by R3-N=M(N(R1)(R2))2 where R1, R2 and R3 independently represent hydrogen or an alkyl group having one to five carbon atoms, and M represents zirconium or hafnium;

forming a dielectric layer including a metal oxide on the lower electrode by chemically reacting the metal organic precursor with the oxidizing agent provided on the substrate; and

forming an upper electrode on the dielectric layer.