Insulative elements

Methods of forming an insulative element are described, including forming a first metal oxide material having a first dielectric constant, forming a second metal oxide material having a second dielectric constant different from the first, and heating at least portions of the structure to crystallize at least a portion of at least one of the first dielectric material and the second dielectric material. Methods of forming a capacitor are described, including forming a first electrode, forming a dielectric material with a first oxide and a second oxide over the first electrode, and forming a second electrode over the dielectric material. Structures including dielectric materials are also described.

TECHNICAL FIELD

Embodiments of the present disclosure relate to forming an insulative element having a high dielectric constant (k) and a low leakage current. Specific embodiments of the present disclosure relate to forming the insulative element having a high k and low leakage current from a metal oxide material doped with another, different metal oxide material.

BACKGROUND

Capacitors are the basic energy storage devices in random access memory devices, such as dynamic random access memory (“DRAM”) devices. Capacitors include two conductors, such as parallel metal or polysilicon plates, which act as electrodes. The electrodes are insulated from each other by a dielectric material. With the continual shrinkage of microelectronic devices, such as capacitors, the materials traditionally used in integrated circuit technology are approaching their performance limits. Silicon dioxide (“SiO2”) has frequently been used as the dielectric material in capacitors. However, with smaller and smaller capacitor area, SiO2cannot be thinned to provide sufficient capacitance while maintaining low leakage. This deficiency has lead to a search for improved dielectric materials. High quality, thin dielectric materials possessing higher dielectric constants (k) than SiO2are of interest to the semiconductor industry. Examples of materials having dielectric constants (k) greater than SiO2include hafnium oxide (“HfO2”), zirconium oxide (“ZrO2”), and strontium titanate (“SrTiO3”). In general, dielectric materials with a higher dielectric constant also exhibit higher leakage currents. Dielectric materials are typically formed by chemical vapor deposition (“CVD”) or atomic layer deposition (“ALD”). However, CVD is unable to provide good step coverage and film stoichiometry in high aspect ratio containers. Therefore, CVD is not useful to fill high aspect ratio containers. While ALD provides good step coverage, current CVD and ALD techniques each produce high-k dielectric materials that have high leakage.

To produce a capacitor, a bottom electrode is formed on a semiconductor substrate and a dielectric material is deposited over the bottom electrode. The bottom electrode and the dielectric material are annealed, and a top electrode is formed over the dielectric material. The dielectric material is typically annealed before the top electrode is formed.

U.S. Pat. No. 7,101,754 discloses forming mixed dielectric films, composed of a high-k dielectric to produce a certain level of capacitance and a relatively lower-k dielectric to control leakage current, on a conductor material. The dielectric film having a composition of SiO2and TiO2made by a sol-gel process is applied onto a substrate using a spin-on technique. The discontinuous layer is annealed in the presence of a reactive species so that exposed portions of the conductor material are converted to an insulating material. However, forming the mixed dielectric films is difficult due to the, oftentimes, conflicting deposition requirements of the high-k dielectric and the relatively lower-k dielectric.

DETAILED DESCRIPTION

The following description provides specific details, such as material types, material thicknesses, and processing conditions in order to provide a thorough description of embodiments of the present invention. However, a person of ordinary skill in the art will understand that the embodiments of the present invention may be practiced without employing these specific details. Indeed, the embodiments of the present invention may be practiced in conjunction with conventional fabrication techniques employed in the industry.

As used herein, the term “amorphous” means and includes without a real or apparent crystalline form, such as non-crystalline or at least substantially non-crystalline.

As used herein, the term “crystalline” means and includes a monocrystalline or polycrystalline chemical structure or phase. A crystalline phase may include one or more molecules of another material.

As used herein, terms such as “first” and “second” are used to merely differentiate between structures, methods, materials, or other components, and do not necessarily refer to any particular sequence.

As used herein, the term “forming” means and includes any method of creating, building, or depositing a material. For example, forming may be accomplished by atomic layer deposition (ALD), chemical vapor deposition (CVD), sputtering, spin-coating, diffusing, depositing, growing, or any other forming technique known in the art of semiconductor fabrication.

As used herein, the term “substantially” means and includes mostly, essentially, fully, or entirely. By way of example, the phrase “a substantially crystalline material” may refer to a material with a portion in a crystalline state, the portion in the range of from about 90% by volume up to and including about 100% by volume of the material, and a remaining portion (i.e., about 10% to about 0% by volume, respectively) in an amorphous state.

As used herein, the term “substrate” refers to any supporting base material, structure, or construction. By way of example and not limitation, a substrate may be a semiconductor substrate, a base semiconductor layer or structure on a supporting structure, a metal or polysilicon electrode, or a semiconductor substrate having one or more layers, structures, or regions formed thereon. In some embodiments, a semiconductor substrate may have at least a portion thereof doped so as to be conductive, such as an n-doped or p-doped silicon substrate.

As used herein, the term “structure” refers to a layer or film, or to a nonplanar mass, such as a three-dimensional mass, having a substantially nonplanar configuration. The term “structure” also may refer to a mass formed of more than one layer, film, non-planar mass, or combination thereof.

Some embodiments of insulative elements including dielectric materials having a high dielectric constant (k) and a low leakage current are shown inFIGS. 1 through 4and are described as follows. Similar structures or components in the various drawings may retain the same or similar numbering for the convenience of the reader; however, the similarity in numbering does not mean that the structures or components are necessarily identical in size, composition, configuration, or any other property. The insulative elements include a first dielectric material and a second dielectric material. During fabrication of the insulative element, the second dielectric material may be formed as a capping material over the first dielectric material and may function as a dopant source for the first dielectric material. Upon exposure to heat, the second dielectric material may form an alloy phase with the first dielectric material. In combination, the first dielectric material and the second dielectric material may form a dielectric material of the insulative element.

In some embodiments, an insulative element10, as shown in any ofFIGS. 1 through 3, may be used as a component of a semiconductor device. By way of example, the insulative element10may be useful as a dielectric material in a capacitor, such as in a planar cell, trench cell, (e.g., double sidewall trench capacitor), or stacked cell (e.g., crown, V-cell, delta cell, multi-fingered, or cylindrical container stacked capacitor). The insulative element10may also be useful as a gate dielectric in a transistor, or as an insulating material between conductive components or portions thereof that are to be isolated electrically. While the intended uses of the insulative elements10are described herein, any application where high-k dielectric materials may be desirable is contemplated by the present disclosure. The insulative element10may be used in a metal-insulator-metal (MIM) capacitor or a metal-insulator-semiconductor (MIS) capacitor or gate stack. The insulative element10may provide a high dielectric constant (k) and a low leakage current to a semiconductor device that includes the insulative element10.

As shown inFIG. 1, some embodiments of the present disclosure include an insulative element10having a high dielectric constant (k) with low leakage current. The insulative element10may include a first dielectric material20and a second dielectric material22over a substrate24. In some embodiments, the substrate24may be or include a conductive material, such as at least one of polysilicon and a metal including, but not limited to, platinum, aluminum, iridium, rhodium, ruthenium, titanium, tantalum, tungsten, alloys thereof, and combinations thereof. If the insulative element10is to be used in a MIM capacitor, the substrate24may be a metal electrode. If the insulative element10is to be used in a MIS capacitor or gate stack, the substrate24may be silicon.

The first dielectric material20and the second dielectric material22may each include at least one metal oxide material, with the first dielectric material20and the second dielectric material22including different metal oxide materials that have different dielectric constants (k). To provide the different dielectric constants (k), the metal oxide materials of the first dielectric material20and the second dielectric material22may differ in the elements present therein or in the stoichiometry of the elements present therein. By way of example and not limitation, the metal oxide material of the first dielectric material20may include one or more of a hafnium oxide (HfyOx, such as HfO2), a zirconium oxide (ZryOx, such as ZrO2), an aluminum oxide (AlyOx, such as Al2O3), a strontium oxide (SryOx, such as SrO), a titanium oxide (TiyOx, such as TiO2), a niobium oxide (NbyOx, such as Nb2O5), a tantalum oxide (TayOx, such as Ta2O5), and a rare earth oxide, wherein each of x and y is an integer greater than or equal to 1. As used herein, the phrase “rare earth oxide” refers to an oxide of a rare earth element, including the elements scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). The first dielectric material20may also include one or more of a silicon oxide (SiyOx, such as SiO2), a germanium oxide (GeyOx, such as GeO2), and an oxynitride (such as SiOxNyor HfOxNy).

The second dielectric material22may include a metal oxide or combinations of metal oxides different from the first dielectric material20. The second dielectric material22may include one or more of the metal oxides described above for the first dielectric material20, such as at least one of HfO2, ZrO2, Al2O3, SrO, TiO2, Nb2O5, Ta2O5, and a rare earth oxide. The second dielectric material22may also include one or more of SiO2, GeO2, and an oxynitride. The composition of the second dielectric material22may differ from the composition of the first dielectric material20in that the second dielectric material22may include different elements than the first dielectric material20or, if the same elements are present, a different stoichiometry of the respective elements. In some embodiments, the second dielectric material22may include one or more of the same metal oxides as the first dielectric material20, in addition to another metal oxide material. For example, where the first dielectric material20includes primarily HfO2, the second dielectric material22may include HfO2in combination with another metal oxide, such as TiO2. Therefore, the overall composition of the second dielectric material22may differ from the overall composition of the first dielectric material20, although some similarity in composition may be present.

In some embodiments, the first dielectric material20includes one or more of HfO2and ZrO2and, optionally, one or more of Al2O3and SiO2, and the second dielectric material22includes one or more of SrO, TiO2, Nb2O5, Ta2O5, and the rare earth oxide. For example, the first dielectric material20may include at least one of HfO2and ZrO2and at least one of SiO2and Al2O3, the latter of which, if present, may account for a relatively small proportion of the first dielectric material20. The second dielectric material22may, optionally, also include one or more of SiO2, Al2O3, ZrO2, and another material, in addition to the one or more of SrO, TiO2, Nb2O5, Ta2O5, and the rare earth oxide. The first dielectric material20may also include at least a portion (such as the portion closest to the second dielectric material22) within which molecules of the second dielectric material22are dispersed. In other words, the portions of the first dielectric material20may be “doped” with metal oxide molecules of the second dielectric material22. As used herein, the term “dispersed” means and includes located within, and may refer to varying concentrations across a region (i.e., heterogeneous) or may refer to a substantially constant concentration across a region (i.e., homogeneous). Molecules dispersed in a structure or material may refer to molecules located at various positions in the structure or material. For example, dispersed molecules may include molecules of the second dielectric material22incorporated into the crystalline phase of the first dielectric material20, located between the grain boundaries of the crystalline phase of the first dielectric material20, located in an amorphous portion of the first dielectric material20, or combinations thereof.

The metal oxide material of the second dielectric material22may be selected to have a dielectric constant (k) higher than the dielectric constant (k) of the metal oxide material of the first dielectric material20. For example, if the first dielectric material20includes primarily HfO2, which has a dielectric constant (k) of about 25, the second dielectric material22may include primarily Nb2O5, which has a dielectric constant (k) of about 41. However, the selection of metal oxide materials of the first and second dielectric materials20,22may be altered such that the metal oxide material of the second dielectric material22has a dielectric constant (k) lower than the dielectric constant (k) of the metal oxide material of the first dielectric material20. The difference in dielectric constant (k) between the first and second dielectric materials20,22may be less than about 5.

In some embodiments, a material forming a majority of a region or material may be referred to as a matrix, and a material forming a smaller portion of the region may be referred to as a dopant. The matrix may have the dopant(s) dispersed therein. By way of example, the first dielectric material may function as the matrix while the metal oxide of the second dielectric material may function as the dopant(s).

In some embodiments, there may be no clear interface or boundary between the first dielectric material20and the second dielectric material22. For example, some regions of the first dielectric material20may exhibit a relatively higher concentration of metal oxide molecules from the second dielectric material22and other regions of the first dielectric material20may exhibit a relatively lower concentration of metal oxide molecules from the second dielectric material22. However, for convenience and clarity, the first and second dielectric materials20,22are illustrated herein as having a distinct interface between adjacent materials.

The first dielectric material20may be formed at a greater thickness than the second dielectric material22. For example, the first dielectric material20may have a thickness of between about 30 Angstroms (Å) and about 80 Å, and the second dielectric material22may have a thickness of between about 5 Å and about 30 Å. The second dielectric material22may be sufficiently thin such that its contribution to the total thickness of the dielectric material14(the first dielectric material20and the second dielectric material22, seeFIG. 4) is minimal compared to its contribution to the dielectric constant of the first dielectric material20and the second dielectric material22. Depending on the intended use of the insulative element10, one or both of the first and second dielectric materials20,22may be thicker or thinner than the ranges recited.

The first dielectric material20of the insulative element10may be substantially crystalline, although some portions of the first dielectric material20may be amorphous. In some embodiments, the second dielectric material22may be substantially crystalline. However, in other embodiments, the second dielectric material may be substantially amorphous. In some embodiments, at least a portion of the metal oxides of the second dielectric material22may be distributed in the first dielectric material20. In other words, at least some of the metal oxide molecules of the second dielectric material22may be incorporated into or distributed within or between the lattice or crystalline phase of the first dielectric material20. As described in more detail below, molecules of the metal oxide of the second dielectric material22may diffuse into the first dielectric material20, doping the first dielectric material20with the metal oxide of the second dielectric material22. A crystalline dielectric material generally has a higher dielectric constant (k) compared to the same dielectric material in an amorphous phase or state. Thus, the dielectric constant (k) of the insulative element10may be tailored by crystallizing none, some, portions of, or substantially all of the first and second dielectric materials20,22, for example.

The crystalline phase of one or both of the first and second dielectric materials20,22may be achieved by annealing one or both of the metal oxide materials of the first and second dielectric materials20,22. Additionally, the dispersion of molecules of the second dielectric material22within the first dielectric material20(also referred to as “doping” of the first dielectric material20) may be accomplished by annealing the metal oxide material of the first and second dielectric materials20,22. As used herein, “annealing” refers to subjecting to elevated temperatures, or heating, for a period of time. A more detailed description of annealing and crystallizing the metal oxide materials is provided below. Annealing one or both of the metal oxide materials of the first and second dielectric materials20,22may provide the insulative element10having the higher k compared to a so-called “mixed dielectric” in which a material including a mixture of two dielectric materials is formed and then annealed.

Referring now toFIG. 2, in some embodiments, one or more additional materials may be present as a part of the insulative element10. For example, an additional dielectric material26may be located between the first dielectric material20and the second dielectric material22. The additional dielectric material26may function as a barrier material, preventing or reducing the diffusion and dispersion of molecules of the second dielectric material22across the additional dielectric material26.

In some embodiments, the insulative element10may include the additional dielectric material26located over the second dielectric material22(i.e., on the side of the second dielectric material22opposite the first dielectric material20, shown by dashed lines inFIG. 2as additional dielectric material26a) or located between the substrate24and the first dielectric material20(shown by dashed lines inFIG. 2as additional dielectric material26b), rather than or in addition to between the first and second dielectric materials20,22. The additional dielectric material26may modulate diffusion of the second dielectric material22into the first dielectric material20.

The additional dielectric material26may include one or more of HfO2, SiO2, ZrO2, Al2O3, GeO2, and a rare earth oxide. The additional dielectric material26may have a different composition than the first dielectric material20, the second dielectric material22, or both the first and second dielectric materials20,22. In some embodiments, the additional dielectric material26may include one or more similar metal oxides to the metal oxide(s) of the first, second, or first and second dielectric materials20,22. By way of example and not limitation, in an embodiment where the first dielectric material20includes primarily HfO2and the second dielectric material22includes primarily TiO2, the additional dielectric material26may include primarily SiO2or Al2O3. The overall composition of the additional dielectric material26may differ from the overall composition of one or both of the first and second dielectric materials20,22, although some similarity in composition may occur.

The additional dielectric material26may, in some embodiments, have a thickness that is less than a thickness of the first dielectric material20. In some embodiments, the additional dielectric material26may have a thickness that is less than both a thickness of the first dielectric material20and a thickness of the second dielectric material22. By way of example and not limitation, the dielectric material26may have a thickness in the range of from about one monolayer to about 5 Å.

In some embodiments, the thickness of the additional dielectric material26may not be clearly defined due to diffusion of the additional dielectric material26into one or both of the first dielectric material20and the second dielectric material22. In some embodiments, the first dielectric material20may include at least portions (such as those closest to the second dielectric material22) wherein molecules of the metal oxides of the second dielectric material22are dispersed. In other words, the portions of the first dielectric material20may be “doped” with molecules of the second dielectric material22.

Referring now toFIG. 3, in some embodiments, the first dielectric material20may have a first region33being at least substantially free of molecules of the metal oxide material of the second dielectric material22, and a second region34including molecules of the second dielectric material22dispersed therein. A majority by volume of the first region33and a majority by volume of the second region34of the first dielectric material20may include the same dielectric material, although the second region34may additionally include a higher concentration of molecules of the second dielectric material22dispersed therein than the first region33. In some embodiments, the first region33and the second region34may each be substantially crystalline. In some embodiments, the first region33, the second region34, and the second dielectric material22may each be substantially crystalline.

While embodiments of the insulative element10have been described and illustrated with the first and second dielectric materials20,22having specific compositions and shown to be in specific configurations, it is to be understood that these descriptions may be altered. For example, a material with a composition similar or identical to the second dielectric material22may be formed on a substrate24first, and a material with a composition similar or identical to the first dielectric material20may be formed over the second dielectric material22. In some embodiments, overall properties (e.g., dielectric constant, capacitance, leakage current) of the insulative element10may be changed or tailored by altering the configuration of the first dielectric material20and the second dielectric material22.

Referring now toFIG. 4, some embodiments of the invention include a semiconductor device structure30including a first electrode12, a second electrode16, and dielectric material14, at least portions of which are located between the first electrode12and the second electrode16. The first electrode12, dielectric material14, and second electrode16may be collectively referred to as a capacitor18.

The first electrode12may be a conductive element, which may include, for example, one or more of polysilicon and a metal, including, but not limited to, platinum, aluminum, iridium, rhodium, ruthenium, titanium, tantalum, tungsten, alloys thereof, and combinations thereof. The dielectric material14may be formed over the first electrode12. The second electrode16may also be a conductive element, which may likewise include, for example, one or more of polysilicon and a metal, including, but not limited to, platinum, aluminum, iridium, rhodium, ruthenium, titanium, tantalum, tungsten, alloys thereof, and combinations thereof.

The dielectric material14may include one of the insulative elements10illustrated and described in reference toFIGS. 1 through 3above and, therefore, may include first and second dielectric materials20and22, which may, by way of example, have a composition as described with reference to any ofFIGS. 1 through 3above or variations and equivalents thereof. For example, the dielectric material14may include the first dielectric material20and the second dielectric material22. The first dielectric material20may be at least substantially crystallized and have a first dielectric constant. The first dielectric material20may be at least partially doped with the second dielectric22material having a second dielectric constant.

Some embodiments of methods of forming insulative elements10or a semiconductor device structure30, such as those shown inFIGS. 1 through 4, are shown inFIGS. 5A through 7Fand are described as follows. First and second oxide materials29,32may be formed over a substrate24and the first and second oxide materials29,32annealed to modulate the interaction between the matrix of the first oxide material29and the dopant of the second oxide material32. The first and second dielectric materials20,22may be formed in this manner. The timing of the anneal in the process flow may determine whether dopant interdiffusion is promoted or inhibited. The timing of the anneal in the process flow may provide the semiconductor device structure30having increased k through enhanced diffusion of the dopant or decreased k by hindering the diffusion of the dopant.

One embodiment of a method showing the formation of an insulative element10(as shown inFIG. 1, for example) or a capacitor is shown inFIGS. 5A through 5D. A first metal oxide material29may be formed on a substrate24, as shown inFIG. 5A. By way of example and not limitation, the substrate24may be or include a capacitor electrode, a portion of a transistor, a semiconductive film, a doped portion of a semiconductor material, any other structure whereon a metal oxide material may be formed, or any combination thereof. The first metal oxide material29may be substantially amorphous at formation. In some embodiments, certain formation techniques, such as CVD, may produce sufficient heat to cause the crystallization of one or more portions of the first metal oxide material29upon formation. However, at least a portion of the first metal oxide material29may remain amorphous during the formation thereof.

By way of example and not limitation, the first metal oxide material29may be formed to a thickness sufficiently thin to enable small feature sizes of an integrated circuit to be formed and to enable high capacitance (which is inversely related to the distance from one electrode to another, i.e., the thickness of the dielectric material14, seeFIG. 4). At the same time, the first metal oxide material29may be formed to be of sufficient thickness to reduce defects and undesirable properties, such as leakage current, in the semiconductor device structure30. By way of example and not limitation, the first metal oxide material29, as formed, may have a thickness in the range of from about 30 Å to about 80 Å.

The first metal oxide material29may be formed from at least one or more of HfO2, ZrO2, Al2O3, SrO, TiO2, Nb2O5, Ta2O5, and a rare earth oxide. The first metal oxide material29may also be formed to include one or more of SiO2, GeO2, and an oxynitride. By way of example and not limitation, the first metal oxide material29may be formed from one or more of HfO2and ZrO2and, optionally, one or more of Al2O3, and SiO2.

A second metal oxide material32may be formed over the first metal oxide material29or portions thereof. The second metal oxide material32may be formed from a material(s) selected to have a different dielectric constant (k) than the first metal oxide material29. For example, the second metal oxide material32may be a material(s) selected to have a higher dielectric constant (k) than the first metal oxide material29. In some embodiments, at least a substantial portion of the second metal oxide material32may be a material with a higher dielectric constant than the first metal oxide material29. By way of example, the second metal oxide material32may be formed from one or more of SrO, TiO2, Nb2O5, Ta2O5, and a rare earth oxide when the first metal oxide material29is formed from one or more of HfO2, ZrO2, SiO2, and Al2O3. Optionally, the second metal oxide material32may also include a material(s) having a relatively lower dielectric constant (k), such as, for example, one or more of SiO2, Al2O3, ZrO2, and HfO2.

The second metal oxide material32may be formed to be at least substantially amorphous at formation. In some embodiments, certain formation techniques, such as CVD, may produce sufficient heat to cause the crystallization of some of the second metal oxide material32at formation. However, at least a portion of the second dielectric material22may remain amorphous during the formation thereof.

The second metal oxide material32may be formed to be sufficiently thin to limit its contribution to the total thickness of the dielectric material14. However, the second metal oxide material32may have sufficient thickness to provide a doping effect on the first metal oxide material29. The doping may occur when molecules of the second metal oxide material32diffuse or migrate into the first metal oxide material29. In other words, the second metal oxide material32may be formed at a sufficient thickness to provide an effective amount of material to dope the first metal oxide material29to tailor the properties (e.g., dielectric constant (k) and leakage current) of the overall insulative element10or semiconductor device structure30. The second metal oxide material32may have a thickness that is the same or different than the thickness of the first metal oxide material29. In some embodiments, the thickness of the second metal oxide material32may be less than the thickness of the first metal oxide material29. By way of example and not limitation, the second metal oxide material32may have a thickness, as formed, in the range of from about 5 Å to about 30 Å.

In one embodiment, the first metal oxide material29is ZryOxand the second metal oxide material32is a mixture of ZryOxand NbyOx. In one embodiment, the first metal oxide material29is ZryOxand the second metal oxide material32is a mixture of SryOxand NbyOx. In one embodiment, the first metal oxide material29is ZryOxand the second dielectric material22is a mixture of SryOx, NbyOx, and TiyOx. In one embodiment, the first metal oxide material29is ZryOx, the second dielectric material32is a mixture of TiyOxand SiOx, and the additional dielectric material26is AlyOx.

In some embodiments, the first and second metal oxide materials29,32may be heated, as shown by arrows40inFIG. 5C. Heating (i.e., annealing) may cause at least some crystallization of the first metal oxide material29, producing first dielectric material20. The annealing may also cause or induce the migration or diffusion of at least some of the metal oxides of the second metal oxide material32into the first metal oxide material29. In other words, the first metal oxide material29may become at least partially doped with molecules of the second metal oxide material32through the annealing. The first and second metal oxide materials29,32are denoted inFIGS. 5C and 5Das first and second dielectric materials20,22to indicate that the materials have been annealed. The interface between the first and second dielectric materials20,22may not be as distinct or clear as is illustrated inFIG. 5C. For example, in some embodiments, the interface may more accurately be represented by a gradient of varying concentration of metal oxides of the second dielectric material22in the first dielectric material20. In some embodiments, substantially all of the second dielectric material22may be incorporated into the first dielectric material20by way of diffusion.

In some embodiments, annealing may also cause at least some crystallization of the second metal oxide material32. The temperature used to anneal and crystallize a dielectric material may depend on the composition of the dielectric material. The amount of time to which the first and second metal oxide materials29,32are exposed to heat may depend on the anneal temperature. At a relatively high anneal temperature, the amount of time to induce crystallization may be less than the amount of time to induce crystallization at a relatively lower temperature. The anneal temperature and anneal time may be chosen to tailor the level of crystallization of at least portions of at least one of the first and second dielectric materials20,22. The anneal temperature and anneal time may also be selected to tailor the amount of dopant diffusion between the first and second dielectric materials20,22. By way of example and not limitation, the anneal temperature may be in the range of from about 300° C. to about 700° C., such as from about 500° C. to about 700° C., and the anneal time may be in the range of from about 1 minute to about 60 minutes, such as from about 3 minutes to about 5 minutes. The anneal may be conducted by increasing the temperature in a gradient or stepwise manner, or by raising the temperature to the desired temperature.

Annealing may take place in any atmosphere, depending on the desired properties of the first and second dielectric materials20,22for their intended use. For example, annealing may take place in an inert (e.g., non-reactive) atmosphere, such as N2, Ar, or He, in an oxidizing atmosphere, or in a reducing atmosphere.

Optionally, the first metal oxide material29may be annealed and at least partially crystallized before the second metal oxide material32is formed thereon (not shown). After the second metal oxide material32is formed, the first and second metal oxide materials29,32may be annealed again. This process may result in an insulative element10including first and second dielectric materials20,22having an effective dielectric constant that is lower than an effective dielectric constant resulting from a process in which the anneal and crystallization of the first metal oxide material29is not conducted before the formation of the second metal oxide material32. Without being bound to a particular theory, it is believed that molecules from the second metal oxide material32diffuse more readily into an at least partially amorphous first metal oxide material29than into an at least partially crystallized first metal oxide material29. The amount of diffusion between the first and second metal oxide materials29,32may affect the overall dielectric constant of an insulative element10that includes the first and second dielectric materials20,22.

In some embodiments, the crystallization of at least portions of one or more of the first metal oxide material29and the second metal oxide material32may be induced through process acts involving heat that occur after forming the first and second metal oxide materials29,32, and not by a separate anneal act as described with reference toFIG. 5C. Additionally, the dispersion of molecules (also referred to as “doping”) from the second metal oxide material32into the first metal oxide material29may be accomplished through process acts involving heat that occur after forming the first and second metal oxide materials29,32, and not by a separate anneal act as described with reference toFIG. 5C. For example, the first and second metal oxide materials29,32may at least partially include one or more amorphous regions at formation. After formation of the first and second metal oxide materials29,32over the substrate24, one or more further processing acts, such as a backend process, may occur that subject the first and second metal oxide materials29,32to heat for a desired period of time. By way of example, later deposition, diffusion, or anneal acts involved in forming or modifying one or more other structures (such as, for example, an electrode, a capping layer, contacts, or insulating layers) of the semiconductor device structure30may produce sufficient heat to crystallize one or more portions of the first and second dielectric metal oxide materials29,32, thus promoting dispersion of molecules from the second metal oxide material32into the first dielectric metal oxide material29(i.e., doping). In such embodiments, a separate anneal act (as described with reference toFIG. 5C) may not be utilized to achieve the crystallization and doping that may be desired in a specific application.

Referring now toFIG. 5D, optionally, one or more additional materials38may be formed over the second dielectric material22. For example, in embodiments where the first and second dielectric materials20,22are used as a capacitor dielectric (e.g., as the dielectric material14shown inFIG. 4), the substrate24may be or include a first electrode and the one or more additional materials38may be or include a second electrode. The second electrode may be formed by conventional semiconductor fabrication techniques, which are not described in detail herein.

By way of another example, in embodiments where the first and second dielectric materials20,22are used as a gate dielectric in a volatile transistor (not shown), the substrate24may be a semiconductor substrate and the one or more additional materials38may be an electrically conductive gate structure. The conductive gate structure may be formed by conventional semiconductor fabrication techniques, which are not described in detail herein. By way of yet another example, in embodiments where the first and second dielectric materials20,22are used as a dielectric structure in a non-volatile transistor (not shown), the substrate24may be a conductive charge retaining material and the one or more additional materials38may be a conductive control gate material. The conductive control gate material may be formed by conventional semiconductor fabrication techniques, which are not described in detail herein.

Another embodiment of a method of forming an insulative element10(as shown inFIG. 2, for example) or a capacitor is shown inFIGS. 6A through 6E.

A first metal oxide material29may be formed on a substrate24, as shown inFIG. 6Aand as described above in relation toFIG. 5A. An additional oxide material27may be formed over the first metal oxide material29, as shown inFIG. 6B. In some embodiments, the additional oxide material27may be a thin layer (relative to the thickness of the first metal oxide material29) of material having a different dielectric constant than the first metal oxide material29. For example, the additional oxide material27may be formed to have a thickness in the range of about one monolayer to about 5 Å at formation.

The additional oxide material27may function as a diffusion barrier to reduce, control, or eliminate diffusion or migration of dopants across the thickness of the additional oxide material27in a subsequent process involving heating of the insulative element10. The additional oxide material27may be formed to include, by way of example, one or more of HfO2, SiO2, Al2O3, GeO2, an oxynitride, and a rare earth oxide. For example, the additional oxide material27may be or include a metal oxide material.

A second metal oxide material32may be formed over the additional oxide material27, as shown inFIG. 6Cand as explained above with reference toFIG. 5B. The second metal oxide material32may be selected to have a different dielectric constant than the first metal oxide29and the additional oxide material27. For example, the second metal oxide material32may have a higher dielectric constant than the first metal oxide material29.

The first metal oxide material29, second metal oxide material32, and additional oxide material27may be annealed to induce one or more of crystallization and diffusion, as shown by arrows40inFIG. 6D. Without being bound to a particular theory, the presence of the additional oxide material27between the first and second metal oxide materials29,32may substantially reduce, control, or eliminate diffusion (e.g., doping) of the first metal oxide material29with molecules of the second metal oxide material32during the annealing process. However, the anneal may cause molecules from the additional oxide material27to diffuse into at least one of the first metal oxide material29and the second metal oxide material32. One or more of the first metal oxide material29, second metal oxide material32, and additional oxide material27may be at least partially crystallized by the annealing. For example, substantially all of the first metal oxide material29may be crystallized by the annealing.

Optionally, the annealing may not occur at this point in the process. Instead, the annealing may occur during a subsequent process act, such as by heating from a backend process. By way of example and not limitation, any other subsequent deposition, diffusion, or anneal acts in conjunction with forming the semiconductor device structure30incorporating an insulative element10formed by this method may provide sufficient heat to crystallize at least a portion of the first metal oxide material29. The heat from the backend process may also induce diffusion of dopants between the additional oxide material27and at least one of the first metal oxide material29and the second metal oxide material32.

The annealing or heating from a backend process may induce crystallization and doping of one or more of the first metal oxide material29, second metal oxide material32, and additional oxide material27, resulting in an insulative element including a first dielectric material20, a second dielectric material22, and an additional dielectric material26, as illustrated inFIG. 6D.

Optionally, one or more additional materials38may be formed over the second dielectric material22, as shown inFIG. 6Eand as explained above with reference toFIG. 5C. For example, the dielectric material formed by this method may function as a capacitor dielectric, and the substrate24may be or include a first electrode and the one or more additional materials38may be or include a second electrode. The second electrode may be formed by conventional semiconductor fabrication techniques, which are not described in detail herein.

The method described with reference toFIGS. 6A through 6Emay, in some embodiments of the invention, be altered by forming the additional dielectric material26at a different location. For example, the additional dielectric material26may be formed before the first metal oxide material29(i.e., the additional dielectric material26may be located between the substrate24and the first dielectric material20) (not shown). By way of another example, the additional dielectric material26may be formed after the second metal oxide material32(i.e., the additional dielectric material26may be located between the second dielectric material22and the one or more additional materials38) (not shown). In some embodiments, more than one additional dielectric material26may be formed, and multiple locations in the dielectric structure may have an additional dielectric material26. Each variation in location of the one or more additional dielectric materials26may change the properties (e.g., capacitance, dielectric constant, leakage current) of the insulative element10formed by the methods described. In this manner, the properties of the dielectric structure may be tailored to the specific application contemplated.

Another embodiment of a method of forming an insulative element10(as shown inFIG. 3, for example) or a capacitor is shown inFIGS. 7A through 7F.

A first region35of a first metal oxide material29may be formed on a substrate24, as shown inFIG. 7Aand as described above in relation toFIG. 5A. The first region35may be at least substantially amorphous at formation. Next, the first region35may be annealed to induce at least some crystallization of the first region35of the first metal oxide material29, as shown by the arrows42representing a first anneal inFIG. 7B. This first anneal may result in an at least partially crystallized first region33of a first dielectric material20(seeFIG. 3). In some embodiments, at least substantially all of the first region33may be crystallized through the first anneal.

After the first region33is annealed and at least partially crystallized, a second region36of the first metal oxide material29may be formed over the first region33, as shown inFIG. 7C. The second region36may be at least substantially amorphous at formation. The relative thicknesses of the first region35and the second region36may be adjusted to tailor the dielectric constant (k) of the insulative element10.

A second metal oxide material32may be formed over the second region36, as shown inFIG. 7Dand as explained above with reference toFIG. 5B. The second metal oxide material32may be selected to have a different dielectric constant than the first and second regions35,36of the first metal oxide material29. For example, the second metal oxide material32may be selected to have a higher dielectric constant than the first metal oxide material29.

The first region33, the second region36, and the second metal oxide material32may be annealed, as shown by arrows44representing a second anneal, to induce one or more of crystallization and diffusion, as shown inFIG. 7E. Without being bound to a particular theory, the initial crystallization or pre-crystallization of the first region35of the first metal oxide material29(forming an at least partially crystallized first region33) may reduce, control, or eliminate doping of the first region33with molecules from the second metal oxide material32during the annealing process, while the amorphous state of the second region36of the first metal oxide material29may enable at least some doping of the second region36with molecules of the second metal oxide material32during the annealing process. By way of example and not limitation, this method may result in a first region33of a first dielectric material20being at least substantially free of dopants from the second metal oxide material32and a second region34of a first dielectric material20including dopants from the second metal oxide material32dispersed therein (seeFIGS. 7E and 7F).

Optionally, one or more additional materials38may be formed over the second dielectric material22, as shown inFIG. 7Fand as explained above with reference toFIG. 5C. In embodiments where this method is used to form a capacitor, the substrate24may be or include a first electrode and the one or more additional materials38may be or include a second electrode. The second electrode may be formed by conventional semiconductor fabrication techniques, which are not described in detail herein.

The method described with reference toFIGS. 7A through 7Fmay, in some embodiments of the invention, be altered by omitting the second anneal represented by arrows44inFIG. 7Eand replacing it with heat produced by a backend process. For example, any other subsequent deposition, diffusion, or anneal in conjunction with forming an integrated circuit incorporating an insulative element10formed by this method may provide sufficient heat to crystallize at least a portion of the second region36and to induce diffusion of at least some dopants from the second metal oxide material32into the second region36, forming an at least partially crystallized and doped second region34of the first dielectric material20. In this manner, the heat sufficient to crystallize at least a portion of the second region34and to induce diffusion of at least some dopants from the second metal oxide material32into the second region34may be provided by a backend process rather than by a separate anneal act (as shown inFIG. 7E).

CONCLUSION

In one embodiment, a method of forming an insulative element is described including forming a first metal oxide material on a substrate, forming a second metal oxide material over at least a portion of the first metal oxide material, and heating at least one of the first metal oxide material and the second metal oxide material to crystallize at least a portion thereof.

In a further embodiment, a method of forming an insulative element is described, including forming a substantially crystalline dielectric material on a substrate, forming a metal oxide material having a greater dielectric constant than the substantially crystalline dielectric material over the substantially crystalline dielectric material, and heating the substantially crystalline dielectric material and the metal oxide material to induce diffusion of dopants from the metal oxide material into the substantially crystalline dielectric material.

In an additional embodiment, a method of forming a capacitor is described, including forming a first electrode, forming a dielectric material over and in contact with the first electrode including forming a first oxide and a second oxide, heating at least one of the first and second oxides, and forming a second electrode over the dielectric material. The heating of the at least one of the first and second oxides at least partially crystallizes at least one of the first and second oxides.

In another embodiment, an insulative element is described, including a substantially crystalline first dielectric material having a first dielectric constant on a substrate and a second dielectric material having a second dielectric constant different than the first dielectric constant positioned over the first dielectric material. The first dielectric material may include dopants of the second dielectric material dispersed therein. The dielectric structure may also include an additional dielectric material.

In an additional embodiment, an insulative element is described, including a substrate and a first dielectric material in contact with at least a portion of the substrate. The first dielectric material may include an at least substantially crystalline metal oxide matrix and a metal oxide dopant dispersed within at least a portion thereof. The metal oxide matrix may include a first region including the metal oxide dopant dispersed therein and a second region being substantially free of the metal oxide dopant.