# Patent

## Title
Silylene compositions and methods of use thereof

## Abstract

A silicon precursor composition is described, including a silylene compound selected from among: silylene compounds of the formula: wherein each of R and R1 is independently selected from organo substituents; amidinate silylenes; and bis(amidinate) silylenes. The silylene compounds are usefully employed to form high purity, conformal silicon-containing films of SiO2, Si3N4, SiC and doped silicates in the manufacture of microelectronic device products, by vapor deposition processes such as CVD, pulsed CVD, ALD and pulsed plasma processes. In one implementation, such silicon precursors can be utilized in the presence of oxidant, to seal porosity in a substrate comprising porous silicon oxide by depositing silicon oxide in the porosity at low temperature, e.g., temperature in a range of from 50° C. to 200° C.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a U.S. national phase under the provisions of 35 U.S.C. §371 of International Patent Application No. PCT/US13/42296 filed May 22, 2013, which in turn claims the benefit of priority under 35 USC 119 of U.S. Provisional Patent Application No. 61/652,010 filed on May 25, 2012 and the benefit of priority under 35 USC 119 of U.S. Provisional Patent Application No. 61/732,900 filed on Dec. 3, 2012 . The disclosures of such international patent application and U.S. priority provisional patent applications are hereby incorporated herein by reference in their respective entireties, for all purposes.


FIELD
The present disclosure relates to silicon-based films for fabrication of microelectronic devices, and to silicon precursors useful in depositing such films by vapor deposition processes.
DESCRIPTION OF THE RELATED ART
Low temperature deposition of silicon-based thin-films is of fundamental importance to current semiconductor device fabrication and processes. For the last several decades, SiO2 thin films have been utilized as essential structural components of integrated circuits (ICs), including microprocessor, logic and memory based devices. SiO2 has been a predominant material in the semiconductor industry and has been employed as an insulating dielectric material for virtually all silicon-based devices that have been commercialized. SiO2 has been used as an interconnect dielectric, a capacitor and a gate dielectric material over the years.
The conventional industry approach for depositing high-purity SiO2 films has been to utilize tetraethylorthosilicate (TEOS) as a thin-film precursor for vapor deposition of such films. TEOS is a stable, liquid material that has been employed as a silicon source reagent in chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD), to achieve high-purity thin-films of SiO2. Other thin-film deposition methods (e.g., focused ion beam, electron beam and other energetic means for forming thin-films) can also be carried out with this silicon source reagent.
As IC device dimensions continually decrease, with corresponding advances in lithography scaling methods and shrinkage of device geometries, new deposition materials and processes are correspondingly being sought for forming high integrity SiO2 thin films. Improved silicon-based precursors (and co-reactants) are desired to form SiO2 films, as well as other silicon-containing thin films, e.g., Si3N4, SiC, and doped SiOx high k thin films, that can be deposited at low temperatures, such as temperatures below 400° C., and more preferably below 200° C. To achieve these low deposition temperatures, chemical precursors are required that decompose cleanly to yield the desired films.
The achievement of low temperature films also requires the use and development of deposition processes that ensure the formation of homogeneous conformal silicon-containing films. Chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes are therefore being refined and implemented, concurrently with the ongoing search for reactive precursor compounds that are stable in handling, vaporization and transport to the reactor, but exhibit the ability to decompose cleanly at low temperatures to form the desired thin films. The fundamental challenge in this effort is to achieve a balance of precursor thermal stability and precursor suitability for high-purity, low temperature film growth processes.
In the search for improved silicon precursors, organosilanes such as teramethoxysilane (TMOS), tetrachlorosilane (TCS), hexachlorodisilane (HCDS) and tris(dimethylamido) silane (TDMAS) have been evaluated for ALD deposition of SiO2. Such silicon precursors can be utilized with oxidizing co-reactants, such as O2, O3, N2O, water and Lewis base species to achieve SiO2 thin-films, or with reducing species such as H2 or NH3, to achieve nitride thin-films.
The art continues to seek improvements and new chemistries for vapor deposition of silicon-containing films for manufacture of microelectronic devices.
SUMMARY
The present disclosure relates to silicon precursors useful in depositing silicon-containing films by vapor deposition processes, to films formed using such precursors, and microelectronic devices including such films.
In one aspect, the disclosure relates to silicon precursor composition comprising a silylene compound selected from among:

    silylene compounds of the formula:






wherein each of R and R1 is independently selected from organo substituents;

    amidinate silylenes; and
    bis(amidinate) silylenes.


In another aspect, the disclosure relates to a method of forming a silicon-containing film on a substrate, comprising volatilizing a silicon precursor composition of the present disclosure to produce corresponding precursor vapor, and contacting the precursor vapor with the substrate under vapor deposition conditions to form the silicon-containing film on the substrate.
In a further aspect, the disclosure relates to a microelectronic device comprising a silicon-containing film deposited by such method.
A further aspect of the disclosure relates to a silicon-containing film deposited by such method.
The disclosure in a further aspect relates to a method of maintaining amorphous character of an amorphous hafnium oxide or zirconium oxide material during elevated temperature processing thereof, said method comprising incorporating silicon in said amorphous hafnium oxide or zirconium oxide material from a silicon precursor composition of the present disclosure.
Another aspect of the present disclosure relates to a method of making a capacitor, comprising:

    forming a bottom electrode;
    depositing on the bottom electrode an HfSiO amorphous film by a vapor deposition process, using a silicon precursor composition of the present disclosure, an organohafnium precursor, and an oxic medium in the vapor deposition process; and
    forming a top electrode on the HfSiO amorphous film.


Yet another aspect of the present disclosure relates to a method of making a ferroelectric field effect transistor, comprising:

    forming a base comprising source and drain regions;
    depositing on the base, in contact with the source and drain regions, an oxide layer;
    forming on the oxide layer a HfSiO material by a vapor deposition process, using a silicon precursor composition of the present disclosure, an organohafnium precursor, and an oxic medium in the vapor deposition process;
    depositing a metal-containing layer on the HfSiO material; and
    annealing the HfSiO material to form ferroelectric HfSiO material.


In another aspect, the disclosure relates to a method of sealing porosity in a substrate comprising porous silicon oxide, comprising volatilizing a silicon precursor of the present disclosure, to produce corresponding precursor vapor, and contacting the precursor vapor with the substrate under vapor deposition conditions including (i) temperature in a range of from 50° C. to 200° C. and (ii) presence of oxidant, to deposit silicon oxide in said porosity of the substrate for sealing thereof.
Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plot of thermogravimetric analysis and differential scanning calorimetry (TG/DSC) data for bis(N-t-amyl)ethylenediamine silylene.
FIG. 2 is a plot of vapor pressure, in torr, as a function of inverse temperature, 1/T(° K) for bis(N-t-amyl)ethylenediamine silylene.
FIG. 3 is a plot of deposited film thickness, in Angstroms, as a function of position, in centimeters, of a silicon oxide film deposited by atomic layer deposition (ALD) using bis(N-t-amyl)ethylenediamine silylene as the silicon precursor.
FIG. 4 is a plot of thermogravimetric analysis and differential scanning calorimetry (TG/DSC) data for bis(N-i-propyl)-t-butyl-amidinate bis(trimethylsilyl)amido silylene.
FIG. 5 is a schematic illustration of a metal-insulator-metal capacitor structure utilizing a silicon-containing hafnium oxide film formed using a silicon precursor of the present disclosure.
FIG. 6 is a schematic illustration of a ferroelectric field effect transistor (FeFET) incorporating a ferroelectric HfSiO film formed using a silicon precursor of the present disclosure.



DETAILED DESCRIPTION
The present disclosure relates to silicon precursors that are amenable to use in low temperature vapor deposition processes such as CVD and ALD, to form silicon-based thin films.
As used herein, the term “film” refers to a layer of deposited material having a thickness below 1000 micrometers, e.g., from such value down to atomic monolayer thickness values. In various embodiments, film thicknesses of deposited material layers in the practice of the invention may for example be below 100, 10, or 1 micrometers, or in various thin film regimes below 200, 100, or 50 nanometers, depending on the specific application involved. As used herein, the term “thin film” means a layer of a material having a thickness below 1 micrometer.
It is noted that as used herein and in the appended claims, the singular forms “a”, “and”, and “the” include plural referents unless the context clearly dictates otherwise.
As used herein, the identification of a carbon number range, e.g., in C1-C12 alkyl, is intended to include each of the component carbon number moieties within such range, so that each intervening carbon number and any other stated or intervening carbon number value in that stated range, is encompassed, it being further understood that sub-ranges of carbon number within specified carbon number ranges may independently be included in smaller carbon number ranges, within the scope of the invention, and that ranges of carbon numbers specifically excluding a carbon number or numbers are included in the invention, and sub-ranges excluding either or both of carbon number limits of specified ranges are also included in the invention. Accordingly, C1-C12 alkyl is intended to include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl, including straight chain as well as branched groups of such types. It therefore is to be appreciated that identification of a carbon number range, e.g., C1-C12, as broadly applicable to a substituent moiety, enables, in specific embodiments of the invention, the carbon number range to be further restricted, as a sub-group of moieties having a carbon number range within the broader specification of the substituent moiety. By way of example, the carbon number range e.g., C1-C12 alkyl, may be more restrictively specified, in particular embodiments of the invention, to encompass sub-ranges such as C1-C4 alkyl, C2-C8 alkyl, C2-C4 alkyl, C3-C5 alkyl, or any other sub-range within the broad carbon number range. In other words, a carbon number range is deemed to affirmatively set forth each of the carbon number species in the range, as to the substituent, moiety, or compound to which such range applies, as a selection group from which specific ones of the members of the selection group may be selected, either as a sequential carbon number sub-range, or as specific carbon number species within such selection group.
“Alkyls” as used herein include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, s-butyl, t-butyl, pentyl and isopentyl and the like. “Aryls” as used herein includes hydrocarbons derived from benzene or a benzene derivative that are unsaturated aromatic carbocyclic groups of from 6 to 10 carbon atoms. The aryls may have a single or multiple rings. The term “aryl” as used herein also includes substituted aryls. Examples include, but are not limited to phenyl, naphthyl, xylene, phenylethane, substituted phenyl, substituted naphthyl, substituted xylene, substituted phenylethane and the like.
The disclosure, as variously set out herein in respect of features, aspects and embodiments thereof, may in particular implementations be constituted as comprising, consisting, or consisting essentially of, some or all of such features, aspects and embodiments, as well as elements and components thereof being aggregated to constitute various further implementations of the disclosure. The disclosure is described herein in various embodiments, and with reference to various features and aspects. The disclosure contemplates such features, aspects and embodiments in various permutations and combinations, as being within the scope of the present description.
The silicon precursors of the present disclosure are silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents, e.g., H, C1-C12 alkyl, silylalkyl, silylamide, alkylamide, dialkylamide, or aryl. The alkyl moiety in silylalkyl, alkylamide, and dialkylamide substituents may include C1-C12 alkyl substituents, and aryl substituents may include any suitable aromatic substituents, including, for example, C6-C15 aryl substituents.

The silicon (II) compounds of the above formula enable low-temperature CVD and/or ALD formation of silicon-based thin films such as SiO2 and Si3N4. Such compounds exhibit high volatility and chemical reactivity, but are stable with respect to thermal degradation at temperatures involved in volatilization of the precursor and transport of the resulting precursor vapor to the deposition chamber. The chemical reactivity of these precursors allows for film growth at low temperatures at which traditional silicon precursor materials such as TEOS are inert and thus exhibit little to no deposition behavior. The thermal stability of these precursors ensures process stability by limiting undesired decomposition of the silylene during delivery and deposition.
The silicon (II) compounds of the present disclosure can be readily synthesized in good yields from common starting materials, within the skill of the art based on the disclosure herein, without undue effort. The substituents R and R1 in such compounds can be varied to produce a corresponding variety of precursors useful for vapor deposition, e.g., ALD or CVD, with respect to properties such as melting point, thermal stability, and volatility.
An illustrative silicon precursor of the foregoing general formula is bis(N-t-amyl)ethylenediamine silylene:




Thermal analysis data are shown in FIG. 1 for such compound, including thermogravimetric analysis and differential scanning calorimetry (TG/DSC) data. The differential scanning calorimetry curve (DSC curve) in the thermal analysis plot in FIG. 1 shows a melting point of 49° C., and the thermogravimetric plot (TG plot) shows efficient thermal transport with a t50 value of 162° C. (t50 is the temperature corresponding to transport of half of the precursor material). The TG plot also shows a residual mass of less than 1%. Such low residual mass indicates that the compound is stable with respect to thermal degradation at the temperature of the TG determination.
FIG. 2 is a plot of vapor pressure, in torr, as a function of inverse temperature, 1/T(° K) for bis(N-t-amyl)ethylenediamine silylene. The vapor pressure was determined by calibrated isothermal weight loss technique, and the data show a vapor pressure of 1 torr (133.3 Pa) at approximately 82° C.
In addition to the foregoing, the thermal stability of bis(N-t-amyl)ethylenediamine silylene has been explored at 160° C., and it has been found that when pure samples of such precursor were heated for 24 hours, no decomposition of the precursor was observable by proton NMR spectroscopy.
FIG. 3 is a plot of deposited film thickness, in Angstroms, as a function of position, in centimeters, of the deposited film, for a silicon oxide film deposited by atomic layer deposition (ALD) using bis(N-t-amyl)ethylenediamine silylene as the silicon precursor. 200 ALD cycles were carried out in a cross-flow reactor, with the precursor being supplied from an ampoule maintained at temperature of 35° C., and with 30 boost doses/cycle being provided. 20 wt % ozone was utilized as a co-reactant. The process involved the cycle identified in FIG. 3, as conducted at the specified temperature. The ALD deposition rate was approximately 0.2 Å/cycle at temperature of 50° C.-200° C. The thickness was measured by spectroscopic ellipsometry assuming optical properties of SiO2.
The foregoing reflect the superior character of bis(N-t-amyl)ethylenediamine silylene as a representative precursor composition of the present disclosure. Such compound can be delivered to a deposition reactor at high flux at 82° C. and 1 torr (133.3 Pa) pressure. At a delivery temperature above 49° C., and 1 torr (133.3 Pa) pressure, bis(N-t-amyl)ethylenediamine silylene remains a liquid in the precursor delivery system, thereby facilitating precursor liquid delivery and avoiding the challenges associated with solid delivery techniques. In addition, such compound is resistant to thermal decomposition, thereby ensuring process stability by limiting undesired decomposition of the silylene precursor during delivery and deposition.
To illustrate the broad range of possible precursor compounds of the above-described broad formula, a mixed-ligand silylene precursor, (amidinate bis-trimethylsilylamide) silylene, was synthesized as shown below.




Thermal analysis data for the product bis(N-i-propyl)-t-butyl-amidinate bis(trimethylsilyl)amido silylene are shown in FIG. 4, including thermogravimetric analysis and differential scanning calorimetry (TG/DSC) data. The differential scanning calorimetry curve (DSC curve) in the thermal analysis plot in FIG. 4 shows a melting point of 43° C., and the thermogravimetric plot (TG plot) shows efficient thermal transport with a t50 value of 228° C. Bis(N-i-propyl)-t-butyl-amidinate bis(trimethylsilyl)amido silylene thus exhibits good thermal stability and efficient transport characterized by residual mass of less than 1%.
The present disclosure further contemplates bis(amidinate) silylenes of the formula




wherein each R is independently selected from organo substituents, e.g., H, C1-C12 alkyl, silylalkyl, or silylamide, alkylamide, dialkylamide, or aryl. The alkyl moiety in silylalkyl, alkylamide, and dialkylamide substituents may include C1-C12 alkyl substituents, and aryl substituents may include any suitable aromatic substituents, including, for example, C6-C15 aryl substituents.

The silylene precursors of the present disclosure can be used to deposit high-purity thin silicon-containing films by any suitable vapor deposition techniques, including, without limitation, CVD, digital CVD, ALD and pulsed plasma processes. Co-reactants can be used to deposit specific thin-film compositions. For example, water, O2, O3 and N2O can be used to react with the silylene precursors to form SiO2 films. NH3 or alkylamines, e.g., diisopropyl amine, with H2 can be used to form Si3N4 films. Carbon sources, such as methane or ethane can be used to form SiC films. Doped silicate high k films can be formed, involving co-reaction of the dopant species with the silylene precursors, in an oxidizing environment. Other film growth co-reactants can be readily determined by those skilled in the art of thin-film formation methods, for forming other silicon-containing films within the scope of the present disclosure.
The silylene precursors of the present disclosure can be utilized to form conformal silicon-containing films, such as may be required for high aspect ratio features in microelectronic device substrates, e.g., high-density, high-performance integrated circuit devices. Silicon-containing films thus formed can be used in the fabrication of microprocessor, logic and memory devices in which high-quality thin films are required. Further, the amenability of such silylene precursors to low temperature deposition enables silicon-containing films to be formed and thermally sensitive substrates, such as may be encountered in flexible substrate applications and in the manufacture of flat-panel displays.
Silylene precursors of the present disclosure can be utilized in solid delivery systems, such as those employing solid precursor vaporizers, e.g., vaporizers of the type commercially available from ATMI, Inc. (Danbury, Conn., USA) under the trademark ProE-Vap.
Silylene precursors of the present disclosure can also be dissolved in appropriate organic solvents to facilitate liquid delivery of the precursor into standard as well as specialized deposition reactors.
In general, the silylene precursors can be delivered to microelectronic device substrates for contacting therewith in any suitable manner. In the liquid delivery applications, the use of solvent must be compatible with the silylene precursor, and avoid any deleterious reaction or premature decomposition of the precursor in the delivery and process system.
Thus, the disclosure contemplates silicon precursor compositions comprising a silylene compound selected from among:

    silylene compounds of the formula:






wherein each of R and R1 is independently selected from organo substituents;

    amidinate silylenes; and
    bis(amidinate) silylenes.


In such silicon precursor compositions, the silylene compound may comprise a compound of the formula:




wherein each of R and R1 is independently selected from H, C1-C12 alkyl, silylalkyl, silylamide, alkylamide, dialkylamide, and aryl. In one embodiment, the silylene compound comprises bis(N-t-amyl)ethylenediamine silylene.

In another embodiment, the silylene compound may comprise an amidinate silylene, such as bis(N-i-propyl)-t-butyl-amidinate bis(trimethylsilyl)amido silylene.
In a further embodiment, the silylene compound comprises a bis-amidinate silylene, a bis(amidinate) silylene of the formula




wherein each R is independently selected from organo substituents. In a specific embodiment, each R is independently selected from H, C1-C12 alkyl, silylalkyl, silylamide, alkylamide, dialkylamide, and aryl.

The disclosure contemplates a method of forming a silicon-containing film on a substrate, comprising volatilizing a silicon precursor composition of the present disclosure to produce corresponding precursor vapor, and contacting the precursor vapor with the substrate under vapor deposition conditions to form the silicon-containing film on the substrate. The vapor deposition conditions may comprise temperature below 400° C., and preferably comprise temperature in a range of from 50° C. to 200° C.
The silicon-containing film formed in such method may comprise SiO2, or Si3N4. The contacting conducted in such method may be carried out in a chemical vapor deposition process, or an atomic layer deposition process, and may include a liquid delivery process, a solid delivery process, or other suitable delivery scheme whereby the precursor vapor is delivered to the deposition chamber of a reactor system. The contacting may be carried out with a co-reactant, e.g., an oxic co-reactant selected from the group consisting of water, O2, O3 and N2O, or a nitrogenous co-reactant selected from the group consisting of NH3 and alkylamine/H2 mixtures, or a carbonaceous co-reactant selected from the group consisting of methane and ethane.
Such silicon-containing film formation method may in a specific embodiment for the comprise doping the silicon-containing film. The substrate in the various methods of silicon-containing film formation can comprise a microelectronic substrate, e.g., comprising a high aspect ratio feature on which the silicon-containing film is deposited.
The disclosure further contemplates microelectronic device comprising a silicon-containing film deposited by a method of the present disclosure, and further contemplates silicon-containing films deposited by such method, e.g., comprising SiO2, or Si3N4.
The disclosure therefore provides silylene precursor compositions as sources for low temperature deposition of high-purity silicon-containing thin films. The silylene precursor compositions may comprise symmetrical or unsymmetrical alkyl substitution, and may include mixed ligands. The silylene precursor compositions of the disclosure enable the formation of silicon containing conformal thin films of high purity character, by techniques including CVD, pulsed CVD, ALD, and pulsed plasma processes. The silicon-containing thin films enabled by the precursors of the present disclosure include thin films of SiO2, Si3N4, SiC and doped silicates, as used for high k capacitor or gate dielectric films. The silicon-containing films of the disclosure may be deposited on polymeric, plastic or other substrates, in the production of semiconductor products, flat-panel displays, and solar panels.
In various embodiments, the silicon precursors of the disclosure can be used to deposit silicon-containing materials in atomic layer deposition (ALD), chemical vapor deposition (CVD) and pulsed CVD processes, e.g., to deposit silicon-containing films comprising material selected from the group consisting of SiO, SiN, SiO2, SiON, HfSiO, and ZrSiO. In such processes, the silicon precursor may be introduced to the vapor deposition process with a co-reactant such as NH3, N2O, NO, O2, H2O, O3, H2O2, or the like. Vapor deposition processes utilizing the silicon precursors of the present disclosure can be carried out at low deposition temperatures such as temperature in a range such as from 50° to 400° C., more preferably in a range of from 250° to 380° C., still more preferably in a range of from 280° to 350° C., and most preferably in a range of from 300° to 350° C. It will be appreciated that the properties of the silicon-containing material that is deposited will vary with temperature, and that specific temperatures or temperature ranges can be readily determined within the skill of the art, based on the disclosure herein, for the achievement of specific film properties.
The silicon precursors of the disclosure are usefully employed in various embodiments to incorporate silicon into HfO2 and ZrO2 films. When ZrCl4 and HfCl4 are utilized as precursors with H2O as a co-reactant to form high k films on semiconductor surfaces without excessive oxidation of the surface at temperatures on the order of 250 to 350° C., SiCl4 has been used to incorporate SiO2 where increased stability to crystallization of the product high k film is desired, but the process of silicon incorporation is difficult to control and the production of chlorine-free films is difficult to achieve in this temperature regime. The silicon precursors of the present disclosure provide an alternative to the use of chlorosilicon precursors and thereby obviate the deficiencies attendant the use of such chlorosilicon precursors in the formation of high k films, particularly in SiO2 vapor deposition processes such as ALD.
The silicon precursors disclosed herein are also useful in the formation of silicon hafnium oxide ferroelectric films, in which small amounts of silicon are incorporated in HfO2 films.
Further, the silicon precursors of the present disclosure are usefully employed to incorporate silicon in hafnium oxide or zirconium oxide films for maintaining amorphous character in such films. For such purpose, an amorphizingly effective amount of silicon is incorporated in the HfO2 or ZrO2 film by deposition from a silylene precursor of the present disclosure. Such incorporation of silicon may for example be carried out in an atomic layer deposition process, utilizing cyclic exposure of a substrate to a silicon precursor of the disclosure, and an organohafnium or organozirconium precursor, as applicable, with ozone or other oxygen-containing gas. The resulting silicon-containing hafnium oxide films or silicon-containing zirconium oxide films are respectively designated herein as HfSiO and ZrSiO films, wherein the corresponding HfSiO and ZrSiO materials may have any suitable stoichiometric constituency appropriate to their end use application.
Thus, the disclosure contemplates methods in which silicon from precursor vapor formed by volatilization of a silicon precursor of the present disclosure is incorporated in HfO2 material on a substrate to form a HfSiO film as a silicon-containing film. Alternatively, silicon from precursor vapor formed by volatilization of a silicon precursor of the present disclosure may be incorporated in ZrO2 material on the substrate to form a ZrSiO film as the silicon-containing film.
In a specific embodiment, the disclosure contemplates a method of maintaining amorphous character of an amorphous hafnium oxide or zirconium oxide material during elevated temperature processing thereof, comprising incorporating silicon in said amorphous hafnium oxide or zirconium oxide material from a silicon precursor composition of the present disclosure.
Methods of forming silicon-containing films are also contemplated, in which vapor deposition conditions comprise performance of an atomic layer deposition process including deposition of silicon from a silicon precursor composition of the disclosure, deposition of hafnium or zirconium from an organohafnium or organozirconium precursor, and exposure to an oxygen-containing gas. The oxygen-containing gas in such methodology may comprise ozone or other suitable oxygen-containing gas.
As a specific example, a capacitor device 10 having a structure as shown in FIG. 5 may be formed by deposition of silicon from the silylene precursor and hafnium from a suitable organohafnium precursor in an oxic environment, to provide an amorphous film of HfSiO 14 on a bottom electrode 16 formed of titanium nitride or other metal composition. A top electrode 12 formed of titanium nitride or other metal composition then may be deposited on the HfSiO film, to constitute the metal-insulator-metal (MIM) capacitor structure that comprises the amorphous HfSiO film, with the capacitor structure then being submitted to elevated temperature annealing, e.g., at temperature in a range of from 500° C. to 1200° C., or more preferably in a range of from 800° C. to 1200° C., to produce a crystalline Si:HfO film in the product capacitor device.
A corresponding generalized method is therefore provided for making a capacitor, comprising:

    forming a bottom electrode;
    depositing on the bottom electrode an HfSiO amorphous film by a vapor deposition process, using a silicon precursor composition of the disclosure, an organohafnium precursor, and an oxic medium in the vapor deposition process; and
    forming a top electrode on the HfSiO amorphous film.


Such method may further comprise annealing the HfSiO amorphous film to effect crystallization thereof.
In another application, the silylene precursor may be utilized in forming a ferroelectric field effect transistor (FeFET) 20 as illustrated in FIG. 6. Such transistor device includes a base 28 comprising source region 30 and drain region 32, on which is an oxide layer 26, e.g., formed of silicon dioxide (SiO2). Overlying oxide layer 26 is the ferroelectric HfSiO layer 24, capped with a layer 22 of titanium nitride or other metal composition.
In the fabrication of such FeFET device, the ferroelectric HfSiO layer 24 can be formed by vapor deposition process such as chemical vapor deposition or atomic layer deposition, utilizing a silylene precursor of the present disclosure as a silicon source compound, together with an organohafnium precursor, such as tetrakis-dialkylamino hafnium, and ozone or other oxygen containing gas, to effect the formation of the ferroelectric material layer, in which the HfSiO material is in a ferroelectric orthorhombic phase.
FeFET devices of the foregoing type may be utilized in nonvolatile memory applications, in which the nonvolatile memory comprises a multiplicity of such HfSiO FeFETs. The HfSiO films in such FeFETs may be on the order of 3-20 nm, containing a concentration of silicon, measured as Sift, that may for example be in a range of from 1-10 mole percent SiO2 of the HfSiO film. The HfSiO film may be deposited in an amorphous state, and thereafter subjected to elevated temperature annealing, e.g., in a nitrogen ambient, to induce crystallization and formation of the ferroelectric orthorhombic phase, e.g., after deposition of titanium nitride or other electrode material on such film.
Accordingly, a generalized method is provided for making a ferroelectric field effect transistor, comprising:

    forming a base comprising source and drain regions;
    depositing on the base, in contact with the source and drain regions, an oxide layer;
    forming on the oxide layer a HfSiO material by a vapor deposition process, using a silicon precursor composition of the present disclosure, an organohafnium precursor, and an oxic medium in the vapor deposition process;
    depositing a metal-containing layer on the HfSiO material; and
    annealing the HfSiO material to form ferroelectric HfSiO material.


In such method, the oxide layer may comprise SiO2, the metal-containing layer may comprise TiN, the organohafnium precursor may comprise tetrakis-dialkylamino hafnium, the oxic medium may comprise ozone, and the annealing may be carried out to form the ferroelectric HfSiO material comprising an orthorhombic phase.
In another aspect, silylene precursors of the present disclosure can be utilized for low temperature pore sealing of porous silicon oxide substrates of devices comprising copper-based films such as copper metallization in the device structure. Such use takes advantage of the character of silylenes as high reactivity Si(II) compounds. Silylene precursors of the present disclosure have appropriate volatility characteristics and are usefully employed in deposition processes in which such precursors can react with an activated silicon surface at low temperature to deposit silicon in the form of an oxide when the deposition processes carried out in the presence of an oxidant, e.g., ozone or water. Such oxide deposition may for example be carried out in a non-self-limited film growth mode at temperature in a range of from 50° C. to 200° C., to seal pores in porous silicon networks at low temperatures. This low temperature process is conducted at temperatures that limit damage to copper-based films that are already present in the device structure that comprises the substrate on which the silicon oxide is deposited.
Accordingly, the disclosure contemplates a method of sealing porosity in a substrate comprising porous silicon oxide, comprising volatilizing a silicon precursor composition of the present disclosure to produce corresponding precursor vapor, and contacting the precursor vapor with the substrate under vapor deposition conditions including (i) temperature in a range of from 50° C. to 200° C. and (ii) presence of oxidant, to deposit silicon oxide in said porosity of the substrate for sealing thereof. In such method, the substrate may comprise copper, which as discussed above is benefited by the low temperature character of the porosity-sealing process, and an oxidant such as ozone or water may be employed in the process to enable deposition of silicon oxide as a sealant medium in the substrate porosity.
While the disclosure has been set out herein in reference to specific aspects, features and illustrative embodiments, it will be appreciated that the utility of the disclosure is not thus limited, but rather extends to and encompasses numerous other variations, modifications and alternative embodiments, as will suggest themselves to those of ordinary skill in the field of the present disclosure, based on the description herein. Correspondingly, the invention as hereinafter claimed is intended to be broadly construed and interpreted, as including all such variations, modifications and alternative embodiments, within its spirit and scope.

## Claims

1. A silicon precursor composition comprising a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from H, C1-C12 alkyl, silylalkyl, silylamide, alkylamide, dialkylamide, and aryl;
(ii) amidinate silylenes; and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl, wherein the silylene compound comprises bis (N-t-amyl) ethylenediamine silylene.

2. A silicon precursor composition comprising a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents,
(ii) amidinate silylenes, and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl, wherein the silylene compound comprises an amidinate silylene.

3. The silicon precursor composition of claim 2, wherein the silylene compound comprises bis (N-i-propyl)-t-butyl-amidinate bis(trimethylsilyl)amido silylene.

4. A silicon precursor composition comprising a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents,
(ii) amidinate silylenes, and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl,
wherein the silylene compound comprises a bis-amidinate silylene.

5. The silicon precursor composition of claim 4, wherein the bis(amidinate) silylene has the formula




wherein each R is independently selected from organo substituents.

6. The silicon precursor composition of claim 5, wherein each R is independently selected from H, C1-C12 alkyl, silylalkyl, silylamide, alkylamide, dialkylamide, and aryl.

7. A method of maintaining amorphous character of an amorphous hafnium oxide or zirconium oxide material during elevated temperature processing thereof, said method comprising incorporating silicon in said amorphous hafnium oxide or zirconium oxide material from a silicon precursor composition comprising a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents,
(ii) amidinate silylenes; and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl.

8. A method of making a capacitor, comprising:
forming a bottom electrode;
depositing on the bottom electrode an HfSiO amorphous film by a vapor deposition process, using a silicon precursor composition, an organohafnium precursor, and an oxic medium in the vapor deposition process; and
forming a top electrode on the HfSiO amorphous film, wherein the silicon precursor composition comprises a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents;
(ii) amidinate silylenes; and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl.

9. The method of claim 8, further comprising annealing the HfSiO amorphous film to effect crystallization thereof.

10. The method of claim 9, wherein said annealing is conducted at temperature in a range of from 500° C. to 1200° C.

11. A method of making a ferroelectric field effect transistor, comprising:
forming a base comprising source and drain regions;
depositing on the base, in contact with the source and drain regions, an oxide layer;
forming on the oxide layer a HfSiO material by a vapor deposition process, using a silicon precursor composition, an organohafnium precursor, and an oxic medium in the vapor deposition process;
depositing a metal-containing layer on the HfSiO material; and
annealing the HfSiO material to form ferroelectric HfSiO material,
wherein the silicon precursor composition comprises a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents;
(ii) amidinate silylenes; and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl.

12. The method of claim 11, wherein the oxide layer comprises SiO2.

13. The method of claim 11, wherein the metal-containing layer comprises TiN.

14. The method of claim 11, wherein the organohafnium precursor comprises tetrakis-dialkylamino hafnium.

15. The method of claim 11, wherein the oxic medium comprises ozone.

16. The method of claim 11, wherein the annealing is carried out to form the ferroelectric HfSiO material comprising an orthorhombic phase.

17. A method of sealing porosity in a substrate comprising porous silicon oxide, comprising volatilizing a silicon precursor composition to produce corresponding precursor vapor, and contacting the precursor vapor with the substrate under vapor deposition conditions including (i) temperature in a range of from 50° C. to 200° C. and (ii) presence of oxidant, to deposit silicon oxide in said porosity of the substrate for sealing thereof,
wherein the silicon precursor composition comprises a silylene compound selected from among:
(i) silylene compounds of the formula:




wherein each of R and R1 is independently selected from organo substituents;
(ii) amidinate silylenes, and
(iii) bis(amidinate) silylenes,
wherein when each R1 is H, each R is not butyl.

18. The method of claim 17, wherein the oxidant comprises water or ozone.