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  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
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  • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
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  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/455—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
  • C23C16/45523—Pulsed gas flow or change of composition over time
  • C23C16/45525—Atomic layer deposition [ALD]
  • C23C16/45555—Atomic layer deposition [ALD] applied in non-semiconductor technology
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Definitions

• the present application relates generally to methods for forming thin films comprising Group VA elements (Sb, As, Bi, P, N) by atomic layer deposition.
• Such films may find use, for example, in phase change memory (PCM) devices and in optical storage media.
• PCM phase change memory
• Thin films comprising group VA elements are used in many different applications, including, for example, non-volatile phase-change memories (PCM), solar cells, III-V compounds and optical storage materials.
• PCM phase-change memories
• III-V compound semiconductors can be used in many different application areas, including transistors, optoelectronics and other application areas, for example, in bipolar transistors, field effect transistors, lasers, IR detectors, LEDs, wide band gap semiconductors, quantum well or quantum dot structures, solar cells and in monolithic microwave integrated circuits.
• the operation of PCM cells is based on the resistivity difference between amorphous and crystalline states of the active material. A resistivity difference of more than three orders of magnitude can be obtained by many different phase change alloys.
• the switching in a PCM cell is generally accomplished by heating the material locally with suitable current pulses, which, depending on the intensity of the pulse, leave the material in a crystalline or amorphous state.
• suitable current pulses which, depending on the intensity of the pulse, leave the material in a crystalline or amorphous state.
• a wide variety of different PCM cell structures have been reported, many of which use trench or pore-like structures. Sputtering has typically been used in preparing PCM materials, but the more demanding cell structures will require better conformality and more control of the deposition process. Sputtering may be capable of forming simple pore and trench structures, however, future PCM applications will require more complicated 3-D cell structures that cannot be formed using sputtering techniques. Processes with greater precision and control, such as atomic layer deposition (ALD), will be required to make these complicated structures. Using an atomic layer deposition process provides greater precision and control over the deposition, including better conformality and better control of the composition of the deposited film.
• ALD atomic layer deposition
• Atomic layer deposition processes for depositing Sb-containing thin films have been limited, in part, by a lack of appropriate precursors.
• the present application relates generally to methods for forming thin films comprising Group VA elements (Sb, As, Bi, P) by atomic layer deposition.
• ALD methods are also disclosed herein for depositing thin films comprising antimony, along with related compositions and structures.
• the methods generally comprise providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a Sb containing thin film wherein the second vapor phase reactant comprises Sb(SiR ! R 2 R 3 ) 3 , wherein R 1 , R 2 , and R 3 are alkyl groups with one or more carbon atoms.
• the first reactant comprises antimony. In some embodiments the first reactant does not comprise oxygen.
• Methods for forming Ge-Sb-Te thin films on a substrate in a reaction chamber by an ALD process are also disclosed herein.
• the methods generally comprise a plurality of Sb deposition cycles, each cycle comprising alternate and sequential pulses of a first precursor and a second Sb precursor comprising Sb(SiR 1 R 2 R 3 ) 3 , wherein R 1 , R 2 , and R are alkyl groups with one or more carbon atoms; a plurality of Te containing deposition cycles, each cycle comprising alternate and sequential pulses of a third precursor and a fourth precursor comprising Te; and a plurality of Ge containing deposition cycles, each cycle comprising alternate and sequential pulses of a fifth precursor and a sixth precursor comprising Ge.
• Methods for forming Ge-Sb-Se thin films on a substrate in a reaction chamber by an ALD process comprise a plurality of Sb deposition cycles, each cycle comprising alternate and sequential pulses of a first precursor and a second Sb precursor comprising Sb(SiR R R ) 3 , wherein R , R , and R are alkyl groups with one or more carbon atoms; a plurality of Se containing deposition cycles, each cycle comprising alternate and sequential pulses of a third precursor and a fourth precursor comprising Se; and a plurality of Ge containing deposition cycles, each cycle comprising alternate and sequential pulses of a fifth precursor and a sixth precursor comprising Ge.
• Method for making Sb precursors comprise forming a first product by reacting a Group IA metal with a compound comprising Sb; and subsequently combining a second reactant comprising R ⁇ R ⁇ iX with the first product, wherein R 1 , R 2 and R 3 are alkyl groups with one or more carbon atoms and X is a halogen atom, thereby forming a compound with the formula S SiR ⁇ R 3 ⁇ .
• Methods for making precursors comprising a group VA element comprise forming a first product by reacting a Group IA metal with a compound comprising a group VA element; and subsequently combining a second reactant comprising R R 2 R 3 SiX with the first product, wherein R 1 , R 2 and R 3 are alkyl groups with one or more carbon atoms and X is a halogen atom, thereby forming a compound with the formula L(SiR R R ) 3 , wherein L is the group VA element , wherein the group VA element is As, Sb, Bi, N or P.
• Methods for making precursors comprising a group VA element are provided herein.
• the methods comprise forming a first product by reacting a Group IA metal with a compound comprising a group VA element; and subsequently combining a
• Atomic layer deposition (ALD) processes for forming group VA element containing thin film on a substrate in a reaction chamber comprise a plurality of Group VA element deposition cycles, each cycle comprising: providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a group VA element containing thin film wherein the second vapor phase reactant comprises X(SiR 1 R2 R 3 ) 3 , wherein R 1 , R2 , and R 3 are alkyl groups with one or more carbon atoms and X is group VA element (Sb, As, Bi, P); and removing excess second reactant and reaction byproducts, if any, from the reaction chamber.
• Atomic layer deposition (ALD) processes for forming As-containing thin films on a substrate in a reaction chamber comprise a plurality of As deposition cycles, each cycle comprising: providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a As containing thin film, wherein the second vapor phase reactant comprises As(SiR R R ) 3 , and wherein R , R , and R are alkyl groups with one or more carbon atoms; and removing excess second reactant and reaction byproducts, if any, from the reaction chamber.
• Atomic layer deposition (ALD) processes for forming Sb-containing thin films on a substrate in a reaction chamber comprise a plurality of Sb deposition cycles, each cycle comprising: providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a Sb containing thin film wherein the second vapor phase reactant comprises Sb(GeR 1 R 2 R 3 ) 3 , wherein R 1 , R 2 , and R 3 are alkyl groups with one or more carbon atoms; and removing excess second reactant and reaction byproducts, if any, from the reaction chamber.
• Atomic layer deposition (ALD) processes for forming group VA element containing thin films on a substrate in a reaction chamber comprise a plurality of Group VA element deposition cycles, each cycle comprising: providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a group VA element containing thin film wherein the second vapor phase reactant comprises a group VA atom that is bonded to one or more of Si, Ge, or Sn and wherein the group VA element is Sb, As, Bi or P; and removing excess second reactant and reaction byproducts, if any, from the reaction chamber.
• Atomic layer deposition (ALD) processes for forming thin films comprising a group VA element on a substrate in a reaction chamber comprise a plurality of Group VA element deposition cycles, each cycle comprising: providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a thin film comprising a group VA element, wherein the second vapor phase reactant comprises a group VA atom that is bonded to one or more of Si, Ge, or Sn, wherein the group VA element is Sb, As, Bi, N, or P, and wherein the first vapor phase reactant does not comprise a transition metal, Si, or Ge when the group VA atom in the second vapor phase reactant is N; and removing excess second
• Atomic layer deposition (ALD) processes for forming nitrogen- containing thin films on a substrate in a reaction chamber comprise a plurality of deposition cycles, each cycle comprising: providing a pulse of a first vapor phase reactant into the reaction chamber to form no more than about a single molecular layer of the reactant on the substrate, wherein the first vapor phase reactant does not comprise transition metal; removing excess first reactant from the reaction chamber; providing a pulse of a second vapor phase reactant to the reaction chamber such that the second vapor phase reactant reacts with the first reactant on the substrate to form a nitrogen containing thin film, wherein the second vapor phase reactant comprises N(AR R R ) X R 3-X , and wherein x is from 1 to 3, A is Si, Ge or Sn, and R, R ,
• R 2 , and R 3 can be independently selected to be linear, cyclic, branched or substituted alkyl, hydrogen or aryl groups; and removing excess second reactant and reaction byproducts, if any, from the reaction chamber.
• ALD atomic layer deposition
• the methods comprise a first deposition cycle comprising alternate and sequential pulses of a first precursor and a second precursor, the second precursor comprising A(SiR 1 R 2 R 3 ) x , wherein R 1 , R 2 , and R 3 are alkyl groups with one or more carbon atoms and A is Sb, Te, or Se, wherein x is 3 when A is Sb and x is 2 when A is Te or Se; and a second deposition cycle comprising alternate and sequential pulses of a third precursor and a fourth precursor, the fourth precursor comprising A(SiR R R ) x , wherein R , R , and R are alkyl groups with one or more carbon atoms and A is Sb, Te, or Se, and wherein x is 3 when A is Sb and x is 2 when A is Te or Se.
• ALD methods are also disclosed herein for depositing thin films comprising: Sb-Te, Ge-Te, Ge-Sb, Ge-Sb-Te, Al-Sb, In-Sb, Ga-Sb, Zn-Sb, Co-Sb, Ga-As, As-Te, As-Se, In-As, In-Ga-As, As-S, Al-As, Bi, Bi-Te, Bi-Se, In-Bi, Sb-Bi, Ga-Bi, Al- Bi, P-Te, P-Se, In-P, Ga-P, Cu-P, Al-P, B-N, Al-N, Ga-N, In-N and combinations thereof, along with related compositions and structures.
• nanolaminate films can be formed comprising the materials disclosed herein.
• nanolaminates are formed using multiple ALD cycles to deposit a first film followed by multiple ALD cycles to form a second film having a composition different from the first film.
• FIG. 1 a flow chart generally illustrating a method for forming a Sb film in accordance with one embodiment.
• FIG. 2 a flow chart generally illustrating a method for forming a Ge-Sb film in accordance with one embodiment.
• FIG. 3 is a graph of the average growth rate per cycle for Sb thin films versus precursor pulse length.
• FIG. 4 is a gracing incidence x-ray diffractogram of a Sb thin film
• FIG. 5 is a graph of the composition of a Sb-Te film as measured by energy dispersive x-ray (EDX) analysis.
• EDX energy dispersive x-ray
• FIG. 6 is a graph of the average growth rate per cycle for Sb-Te thin films versus the cycling ratio between Sb-Te and Sb cycles.
• FIG. 7 is a gracing incidence x-ray diffractogram of Sb-Te thin films of various compositions.
• FIG. 8 is a graph of the composition of various Ge-Sb films for various Ge-Sb to Sb cycling ratios as measured by EDX analysis.
• FIG. 9 is a graph of the average growth rate per cycle for Ge-Sb thin films versus the cycling ratio between Ge-Sb and Sb cycling ratio.
• FIG. 10 a flow chart generally illustrating a method for synthesizing a compound having the formula Sb(SiR R R ) 3 in accordance with one embodiment.
• FIG. 11 is a graph of nanolaminate composition as a function of the amount of GeTe and Sb 2 Te 3 subcycles.
• FIG. 12 is a graph of resistivity of GeTe, Sb 2 Te 3 , GST and the nanolaminates as a function of annealing temperature.
• FIG. 13 A and 13B are a HTXRD measurement from room temperature to 405 °C of samples D (13 A) and C (13B).
• FIG. 14 is a graph of the average growth rate per cycle for Sb thin films versus deposition temperature.
• FIG. 15 is a time-of-flight elastic recoil detection analysis (TOF- ERDA) of a Sb film deposited at 100°C by ALD.
• TOF- ERDA time-of-flight elastic recoil detection analysis
• FIG. 16(a) illustrates a Sb film deposited on a high aspect ratio trench structure and FIGS. 16(b)-(d) are Sb nanotubes.
• FIG. 17 is a graph illustrating various compositions of Ge-Te-Sb thin films formed by various ALD processes.
• FIG. 18 is a graph of the average growth rate per cycle for Ga-Sb thin films versus GaCl 3 precursor pulse length.
• FIG. 19 is a graph of the average growth rate per cycle for Ga-Sb thin films versus (Et 3 Si) 3 Sb precursor pulse length.
• FIG. 20 is a graph of the composition of a Al-Sb film as measured by EDX analysis.
• FIG. 21 is a TOF-ERDA depth profile of a Ge 22 Sb 78 thin film deposited by ALD.
• FIG. 22 is a thermal gravimetric analysis (TGA) graph of Sb(SiMe 3 )3, Sb(SiEt 3 ) 3 , As(SiEt 3 ) 3 and Bi(SiEt 3 ) 3 , which have been synthesized.
• TGA thermal gravimetric analysis
• PCM cells can have a variety of different configurations.
• the PCM cell includes a transistor and a resistor between a top metal contact and a resistive bottom electrode. Additional PCM configurations are disclosed, for example, in "Phase change memories: State-of-the-art, challenges and perspectives" by Lacaita, Solid-State Electronics 50 (2006) 24-31, which is herein incorporated by reference in its entirety.
• Elemental antimony can also be used as phase change material. Elemental antimony can also be used as an optical material in super-resolution near-field structures (super-RENS).
• Group VA is used herein for clarity although IUPAC nomenclature now uses the term group 15. As used herein Group VA covers the elements of group 15. Group III or IIIA is used herein although IUPAC nomenclature now uses the term group 13. As used herein Group III or IIIA covers the elements of group 13. The term group III- V semiconductor covers a semiconductor with an element from group 15 and an element group 13.
• film and “thin film” are also used herein for simplicity.
• Film and “thin film” are meant to mean any continuous or non-continuous structures deposited by the methods disclosed herein.
• film and “thin film” could include nanorods, nanotubes or nanoparticles.
• embodiments disclosed herein are discussed in the general context of PCM, the skilled artisan will appreciate that the principles and advantages taught herein will have application to other devices and applications.
• processes are disclosed herein, one of ordinary skill in the art will recognize the utility of certain of the disclosed steps in the processes, even in the absence of some of the other disclosed steps, and similarly that subsequent, prior and intervening steps can be added.
• Antimony-telluride including Sb 2 Te and Sb 2 Te 3
• Germanium- telluride including GeTe
• germanium-antimony-telluride GST; Ge 2 Sb 2 Te 5
• bismuth- telluride Bi-Te including Bi 2 Te 3
• zinc-telluride including ZnTe thin films
• ALD cycles for depositing elemental antimony films.
• the elemental antimony cycles can be used with other ALD cycles to deposit a thin film with a precise antimony composition to achieve a thin film with desired properties.
• Antimony has several oxidation states, including -3, +3, 0 and +5, of which +3 is most common.
• Tellurium has several oxidation states, including -2, 0, +2, +4, and +6.
• a stoichiometric Sb-Te film with Te in a -2 oxidation state comprises Sb 2 Te 3 .
• Germanium (Ge) has oxidation states of 0, +2, and +4.
• Tellurium (Te) compounds where Te has an oxidation state of -2, are generally called tellurides.
• Tellurium compounds where Te has an oxidation state of 0, are generally called tellurium compounds.
• These oxidation states in many Te compounds can be just nominal or formal expressions, in reality the situation might be more complex.
• thin films comprising Te are referred to as tellurides.
• films referred to as tellurides herein may contain Te with oxidations states other than -2, for example, oxidation states of 0, +2, +4, and +6. It will be apparent to the skilled artisan when a particular oxidation state is intended.
• ALD type processes are based on controlled, self-limiting surface reactions of precursor chemicals. Gas phase reactions are avoided by feeding the precursors alternately and sequentially into the reaction chamber. Vapor phase reactants are separated from each other in the reaction chamber, for example, by removing excess reactants and/or reactant byproducts from the reaction chamber between reactant pulses.
• a substrate is loaded into a reaction chamber and is heated to a suitable deposition temperature, generally at lowered pressure.
• Deposition temperatures are maintained below the thermal decomposition temperature of the reactants but at a high enough level to avoid condensation of reactants and to provide the activation energy for the desired surface reactions.
• the appropriate temperature window for any given ALD reaction will depend upon the surface termination and reactant species involved.
• the temperature varies depending on the type of film being deposited and is preferably at or below about 400°C, more preferably at or below about 200°C and most preferably from about 20°C to about 200 °C.
• a first reactant is conducted or pulsed into the chamber in the form of a vapor phase pulse and contacted with the surface of the substrate. Conditions are preferably selected such that no more than about one monolayer of the first reactant is adsorbed on the substrate surface in a self-limiting manner. The appropriate pulsing times can be readily determined by the skilled artisan based on the particular circumstances. Excess first reactant and reaction byproducts, if any, are removed from the reaction chamber, such as by purging with an inert gas.
• Purging the reaction chamber means that vapor phase precursors and/or vapor phase byproducts are removed from the reaction chamber such as by evacuating the chamber with a vacuum pump and/or by replacing the gas inside the reactor with an inert gas such as argon or nitrogen.
• Typical purging times are from about 0.05 to 20 seconds, more preferably between about 1 and 10, and still more preferably between about 1 and 2 seconds. However, other purge times can be utilized if necessary, such as where highly conformal step coverage over extremely high aspect ratio structures or other structures with complex surface morphology is needed.
• a second gaseous reactant is pulsed into the chamber where it reacts with the first reactant bound to the surface. Excess second reactant and gaseous byproducts of the surface reaction, if any, are removed from the reaction chamber, preferably by purging with the aid of an inert gas and / or evacuation. The steps of pulsing and purging are repeated until a thin film of the desired thickness has been formed on the substrate, with each cycle leaving no more than a molecular monolayer. Additional phases comprising provision of a reactant and purging of the reaction space can be included to form more complicated materials, such as ternary materials.
• each pulse or phase of each cycle is preferably self-limiting.
• An excess of reactant precursors is supplied in each phase to saturate the susceptible structure surfaces.
• Surface saturation ensures reactant occupation of all available reactive sites (subject, for example, to physical size or "steric hindrance” restraints) and thus ensures excellent step coverage.
• less than one molecular layer of material is deposited with each cycle, however, in some embodiments more than one molecular layer is deposited during the cycle.
• Removing excess reactants can include evacuating some of the contents of the reaction space and/or purging the reaction space with helium, nitrogen or another inert gas.
• purging can comprise turning off the flow of the reactive gas while continuing to flow an inert carrier gas to the reaction space.
• the precursors employed in the ALD type processes may be solid, liquid or gaseous materials under standard conditions (room temperature and atmospheric pressure), provided that the precursors are in vapor phase before they are conducted into the reaction chamber and contacted with the substrate surface.
• "Pulsing" a vaporized precursor onto the substrate means that the precursor vapor is conducted into the chamber for a limited period of time. Typically, the pulsing time is from about 0.05 to 10 seconds. However, depending on the substrate type and its surface area, the pulsing time may be even higher than 10 seconds. Pulsing times can be on the order of minutes in some cases. The optimum pulsing time can be determined by the skilled artisan based on the particular circumstances.
• the mass flow rate of the precursors can also be determined by the skilled artisan.
• the flow rate of metal precursors is preferably between about 1 and 1000 seem without limitation, more preferably between about 100 and 500 seem.
• the pressure in the reaction chamber is typically from about 0.01 to about 20 mbar, more preferably from about 1 to about 10 mbar. However, in some cases the pressure will be higher or lower than this range, as can be determined by the skilled artisan given the particular circumstances.
• the substrate is typically heated to a suitable growth temperature.
• the growth temperature varies depending on the type of thin film formed, physical properties of the precursors, etc. The growth temperatures are discussed in greater detail below in reference to each type of thin film formed.
• the growth temperature can be less than the crystallization temperature for the deposited materials such that an amorphous thin film is formed or it can be above the crystallization temperature such that a crystalline thin film is formed.
• the preferred deposition temperature may vary depending on a number of factors such as, and without limitation, the reactant precursors, the pressure, flow rate, the arrangement of the reactor, crystallization temperature of the deposited thin film, and the composition of the substrate including the nature of the material to be deposited on.
• the specific growth temperature may be selected by the skilled artisan.
• suitable reactors include commercially available ALD equipment such as the F-120 ® reactor, Pulsar ® reactor and Advance ® 400 Series reactor, available from ASM America, Inc of Phoenix, Arizona and ASM Europe B.V., Almere, Netherlands.
• ALD reactors many other kinds of reactors capable of ALD growth of thin films, including CVD reactors equipped with appropriate equipment and means for pulsing the precursors can be employed.
• a flow type ALD reactor is used.
• reactants are kept separate until reaching the reaction chamber, such that shared lines for the precursors are minimized.
• other arrangements are possible, such as the use of a pre-reaction chamber as described in U.S. Application Numbers 10/929,348, filed August 30, 2004 and 09/836,674, filed April 16, 2001, the disclosures of which are incorporated herein by reference.
• the growth processes can optionally be carried out in a reactor or reaction space connected to a cluster tool.
• a cluster tool because each reaction space is dedicated to one type of process, the temperature of the reaction space in each module can be kept constant, which improves the throughput compared to a reactor in which is the substrate is heated up to the process temperature before each run.
• a stand-alone reactor can be equipped with a load-lock. In that case, it is not necessary to cool down the reaction space between each run.
• the examples descried herein illustrate certain preferred embodiments. They were carried out in an F-120TM ALD reactor supplied by ASM Microchemistry Oy, Espoo.
• Sb precursors that may be used include, Sb halides, such as SbCl 3 and Sbl 3 , Sb alkoxides, such as Sb(OEt) 3 and Sb amides.
• the Sb precursor has Sb bound to three silicon atoms.
• it can have a general formula of Sb(AR 1 R 2 R 3 ) 3 , wherein A is Si or Ge, and R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• R 1 , R 2 and R 3 ligands can be selected independently of each other.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• R 1 , R 2 and/or R 3 can be hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• R 1 , R 2 , R 3 can be halogen atoms.
• the Sb precursor have a general formula of Sb(SiR ! R 2 R 3 ) 3 , wherein R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms. .
• R 1 , R 2 and/or R 3 can be unsubstituted or substituted C C 2 alkyls, such as methyl or ethyl groups.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc
• the Sb precursor is Sb(SiMe 2 l Bu) 3 .
• the precursor is Sb(SiEt 3 ) 3 or Sb(SiMe 3 ) 3 .
• the precursor has a Sb-Si bond and most preferably a three Si-Sb bond structure.
• the Sb precursor has a general formula of Sb[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ][A 3 (X 3 R 7 R 8 R 9 ) 3 ] wherein A 1 , A 2 , A 3 can be independently selected to be Si or Ge and wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 , can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• one or more R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be halogen atoms.
• X , X , and X can be Si, Ge, N, or O.
• X , X , and X are different elements.
• Si when X is Si then Si will be bound to three R groups, for example Sb[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ].
• nitrogen when X is N then nitrogen will only be bound to two R groups Sb[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ][Si(NR 5 R 6 ) 3 ].
• the oxygen when X is O, the oxygen will only be bound to one R group, for example SbtSiCOR ⁇ JfS OR ⁇ tS OR 3 ) ⁇ .
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the Sb precursor is selected from the group consisting of: Sb[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ],
• the Sb precursor comprises: a ring or cyclical configuration comprising a Sb atom and multiple Si atoms; or comprises more than one Sb atom.
• R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are selected from the group consisting of alkyl, hydrogen, alkenyl, alkynyl, or aryl groups.
• a partial structure of the precursor formula is represented below:
• the precursor contains multiple atoms of Si and Sb.
• a partial structure of a precursor in one embodiment is represented below: [0076]
• the Si and Sb atoms in the partial formulas pictured above can also be bound to one or more R groups. In some embodiments, any of the R groups described herein can be used.
• the precursor contains a Si-Sb-Si bond structure in a cyclical or ring structure.
• a partial structure of a precursor in one embodiment is represented below.
• the R group can comprise an alkyl, alkenyl, alkynyl, alkylsilyl, alkylamine or alkoxide group. In some embodiments the R group is substituted or branched. In some embodiments the R group is not substituted and/or is not branched.
• the Si and Sb atoms in the partial formula pictured above can also be bound to one or more R groups. In some embodiments, any of the R groups described herein can be used.
• Precursors comprising As that are similar to the precursors comprising Sb.described herein can be used. Formally As have oxidation state -III in compounds described herein.
• the As precursor has As bound to three silicon atoms.
• it can have a general formula of As(AR R R ) 3 , wherein A is Si or Ge, and R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• R 1 , R 2 and/or R 3 can be hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. In some embodiments R 1 , R 2 , R 3 can be halogen atoms. In some embodiments the As precursor have a general formula of
• the R , R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the precursor has an As-Si bond and most preferably a three Si-As bond structure.
• the As precursor is In other embodiments the precursor is As(SiEt 3 ) 3 or As(SiMe 3 ) 3 .
• As(SiMe 3 ) 3 is commercially available and can be used in some embodiments.
• the As precursor has a general formula of As[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ][A 3 (X 3 R 7 R 8 R 9 ) 3 ] wherein A 1 , A 2 , A 3 can be independently selected to be Si or Ge and wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 , can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• R , R R J , R , R R°, R', R°, and R y can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. .
• one or more R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be halogen atoms.
• X , X , and X can be Si, Ge, N, or O. In some embodiments X , X , and X are different elements.
• Si when X is Si then Si will be bound to three R groups, for example As[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ].
• nitrogen when X is N then nitrogen will only be bound to two R groups As[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ][Si(NR 5 R 6 ) 3 ].
• the oxygen when X is O, the oxygen will only be bound to one R group, for example As[Si(OR 1 ) 3 ][Si(OR 2 ) 3 ][Si(OR 3 ) 3 ].
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• Bi precursors comprising Bi that are similar to the precursors comprising Sb.described herein can be used.
• Formally oxidation state of Bi can be either -III or +III in compounds described herein as the electronegativity of Bi is close to Si electronegativity. It must be emphasized that the oxidation state values are just formal, like in As case.
• the Bi precursor has Bi bound to three silicon atoms.
• it can have a general formula of Bi(AR R R ) 3 , wherein A is Si or Ge, and R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure,
• R , R and/or R can be hydrogen, alkenyl, alkynyl or
• R , R , R can be any organic groups containing
• R , R , R can be halogen atoms.
• the Bi precursor have a general formula of
• the R , R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the precursor has a Bi-Si bond and most preferably a three Si-Bi bond structure.
• the Bi precursor is B ⁇ SiMe ⁇ Bu ⁇ .
• the precursor is Bi(SiEt 3 ) 3 or Bi(SiMe 3 ) 3 .
• the Bi precursor has a general formula of Bi[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ][A 3 (X 3 R 7 R 8 R 9 ) 3 ] wherein A 1 , A 2 , A 3 can be independently selected to be Si or Ge and wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 , can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• R , R R J , R R R , R°, R', R°, and R * can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• one or more R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be halogen atoms.
• X , X , and X can be Si, Ge, N, or O. In some embodiments X , X , and X 3 are different elements. In embodiments when X is Si then Si will be bound to three R groups, for example Bi[Si(SiR 1 R R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ]. In embodiments when X is N then nitrogen will only be bound to two R groups Bi[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ][Si(NR 5 R 6 ) 3 ].
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• Precursors comprising P that are similar to the precursors comprising Sb described herein can be used.
• Formally P have oxidation state -III in compounds described herein.
• the P precursor has P bound to three silicon atoms.
• it can have a general formula of P(AR R R ) 3 , wherein A is Si or Ge, and R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• R 1 , R 2 and/or R 3 can be hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. In some embodiments R 1 , R 2 , R 3 can be halogen atoms.
• the P precursor have a general formula of P(SiR 1 R 2 R 3 ) 3 , wherein R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the precursor has a P-Si bond and most preferably a three Si-P bond structure.
• the P precursor is P ⁇ iMe ⁇ Bu ⁇ .
• the precursor is P(SiEt 3 ) 3 or P(SiMe 3 ) 3 .
• P(SiMe 3 ) 3 is commercially available and can be used in some embodiments.
• the P precursor has a general formula of P[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ][A 3 (X 3 R 7 R 8 R 9 ) 3 ] wherein A 1 , A 2 , A 3 can be independently selected to be Si or Ge and wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 , can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• one or more R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be halogen atoms.
• X 1 , X 2 , and X 3 can be Si, Ge, N, or O.
• X 1 , X 2 , and X 3 are different elements.
• Si when X is Si then Si will be bound to three R groups, for example P[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ].
• nitrogen when X is N then nitrogen will only be bound to two R groups P[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ][Si(NR 5 R 6 ) 3 ].
• the oxygen when X is O, the oxygen will only be bound to one R group, for example P[Si(OR 1 ) 3 ][Si(OR 2 ) 3 ][Si(OR 3 ) 3 ].
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• Precursors comprising N that are similar to the precursors comprising Sb described herein can be used in some embodiments.
• a N precursor has N bound to three silicon atoms.
• it can have a general formula of N(AR R R ) X R 3-X , wherein x is from
• A is Si, Ge or Sn and R, R , R , and R are alkyl groups comprising one or more
• R , R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as
• R, R , R and/or R can be
• R, R , R , R can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. In some
• R, R , R , R can be halogen atoms. In some embodiments R, R , R , R are not hydrogen. In some embodiments x is 2 and R is hydrogen.
• a N precursor has a general formula of
• the precursor has a N-Si bond and most preferably a three Si-N bond structure.
• the N precursor is N ⁇ SiM ⁇ 'Bub.
• the precursor is N(SiEt 3 ) 3 or N(SiMe 3 ) 3 .
• the N precursor has a general formula of N[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ][A 3 (X 3 R 7 R 8 R 9 ) 3 ] wherein A 1 , A 2 , A 3 can be independently selected to be Si, Ge or Sn and wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• R , R R J , R , R R°, R', R°, and R * can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• R , R , R R R R°, R', R°, and R * are not hydrogen.
• one or more R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be halogen atoms.
• X can be Si, Ge, N, or O. In some embodiments X and X are different elements. In embodiments when X is Si then Si will be bound to three R groups, for example N[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ]. In embodiments when X is N then nitrogen will only be bound to two R groups ⁇ [8 ⁇ 2 ) 3 ][8 ⁇ 3 ⁇ 4 4 ) 3 ][8 ⁇ 3 ⁇ 4 6 ) 3 ]. In embodiments when X is O, the oxygen will only be bound to one R group, for example NtS OR ⁇ HSiCOR ⁇ HSiCOR 3 ⁇ ].
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the N precursor has a general formula of N[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ]H wherein A 1 , A 2 can be independently selected to be Si, Ge or Sn and wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups. In some embodiments R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are not hydrogen.
• R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. In some embodiments one or more R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be halogen atoms. In some
• X and X can be Si, Ge, N, or O. In some embodiments X and X are different elements. In embodiments when X is Si then Si will be bound to three R groups, for example N[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ]H. In embodiments when X is N then nitrogen will only be bound to two R groups N[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ]H. In embodiments when X is O, the oxygen will only be bound to one R group, for example N[Si(OR 1 ) 3 ][Si(OR 2 ) 3 ]H. R 1 , R 2 , R 3 , R 4 , R 5 and R 6 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• a Group VA element containing precursor has Group VA element bound to three silicon atoms.
• it can have a general formula of L(AR ! R 2 R 3 ) 3 , wherein L is Sb, As, Bi or P, wherein A is Si, Sn, or Ge, and R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• A can be Sn.
• Each of the AR 1 R 2 R 3 -ligands can be independently selected of each other.
• the R 1 , R 2 , and R 3 alkyl groups can also be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• R 1 , R 2 and/or R 3 can be hydrogen, alkenyl, alkynyl or aryl groups. In some embodiments, R , R and/or R can be unsubstituted or substituted Q-C 2 alkyls, such as methyl or ethyl groups. In some embodiments, R 1 , R , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. In some embodiments R 1 , R 2 , R 3 can be halogen atoms.
• the Group VA element containing precursor have a general formula of L(SiR 1 R 2 R 3 ) 3 , wherein L is Sb, As, Bi or P and wherein R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the VA precursor has a formula of I SiM ⁇ Bub.
• the precursor is L(SiEt 3 ) 3 or L(SiMe 3 ) 3 .
• the Group VA element containing precursor comprises a Group VA element bound to one or more of Si, Ge, and Sn. In some embodiments the Group VA element containing precursor has a Group VA element bound to one, two or three atoms selected from Si, Ge, and Sn. In some embodiments the Group VA element containing precursor comprises a Group VA element bound to two or three atoms selected from Si, Ge, and Sn, wherein there are at least two different atoms selected from Si, Ge, and Sn. In some embodiments the Group VA element containing precursor comprises a Group VA element bound to one or more Si atoms.
• L L(AR 1 R 2 R 3 ) X R 3-X , wherein x is from 1 to 3, L is Sb, As, Bi or P, wherein A is Si, Sn, or Ge, and R, R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• R 1 , R 2 and/or R 3 can be unsubstituted or substituted Q-C 2 alkyls, such as methyl or ethyl groups
• A can be Sn.
• R, R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• Each of the AR ! R 2 R 3 -ligands can also be independently selected of each other.
• R, R , R and/or R can be hydrogen, alkenyl, alkynyl or aryl groups.
• R, R 1 , R 2 , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• R, R 1 , R 2 , R 3 can be halogen atoms.
• R can be amino group.
• at least one of the ligands R, R 1 , R 2 , and R 3 is selected from linear, branched or cyclic C C 5 alkyls, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertbutyl, pentyl, isopentyl, tertpentyl.
• the Group VA element containing precursor has
• R 1 9 1 a general formula of L(SiR R R ) X R 3-X , wherein L is Sb, As, Bi or P and wherein R, R , R , and R are alkyl groups comprising one or more carbon atoms. .
• R 1 , R 2 and/or R 3 can be unsubstituted or substituted C 1 -C 2 alkyls, such as
• the R, R , R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the VA precursor has a formula of L(SiMe 2 l Bu) 3 .
• the precursor is L(SiEt 3 ) 3 or L(SiMe 3 ) 3 .
• At least one of the ligands R, R , R , and R is selected from linear, branched or cyclic Ci-C 5 alkyls, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tertbutyl, pentyl, isopentyl, tertpentyl.
• R is a linear, branched, unsubstituted or substituted alkyl, alkenyl, alkynyl, alkylsilyl, alkylamine or alkoxide group.
• the Group VA element containing precursor comprises a Group VA element bound to one or more atoms selected from Si, Ge, Sn with a double bond similar to the Sb precursors described herein.
• a partial structure of the precursor formula is represented below:
• the precursor contains multiple Si or Ge atoms.
• a partial structure of a precursor in one embodiment is represented below:
• Si or Ge and Group VA element atoms in the partial formulas pictured above can also be bound to one or more R groups.
• any of the R groups described herein can be used.
• the precursor contains A-L-A, wherein A is Si or Ge and wherein L is Group VA element atom, bond structure in a cyclical or ring structure.
• A is Si or Ge and wherein L is Group VA element atom, bond structure in a cyclical or ring structure.
• L is Group VA element atom, bond structure in a cyclical or ring structure.
• a partial structure of a precursor in one embodiment is represented below.
• the R group can comprise an alkyl, alkenyl, alkynyl, alkylsilyl, alkylamine or alkoxide group. In some embodiments the R group is substituted or branched. In some embodiments the R group is not substituted and/or is not branched.
• the A and L atoms in the partial formula pictured above can also be bound to one or more R groups. In some embodiments, any of the R groups described herein can be used.
• the Group VA element containing precursor has a general formula of L[A 1 (X 1 R 1 R 2 R 3 ) 3 ][A 2 (X 2 R 4 R 5 R 6 ) 3 ][A 3 (X 3 R 7 R 8 R 9 ) 3 ] wherein L is Sb, As, Bi or P and wherein A 1 , A 2 , A 3 can be independently selected to be Si, Sn, or Ge and wherein R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 , can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• a , A and/or A can be independently selected to be Sn.
• R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• one or more R , R , R R ⁇ R% R°, R', R°, and R y can be halogen atoms.
• X 1 , X 2 , and X 3 can be Si, Ge, N, or O. In some embodiments X 1 , X 2 , and X 3 are different elements.
• Si when X is Si then Si will be bound to three R groups, for example L[Si(SiR 1 R 2 R 3 ) 3 ][Si(SiR 4 R 5 R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ].
• nitrogen when X is N then nitrogen will only be bound to two R groups L[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ][Si(NR 5 R 6 ) 3 ].
• the oxygen when X is O, the oxygen will only be bound to one R group, for example LtSiCOR ⁇ sJtSiCOR ⁇ JtSiCOR 3 ⁇ ].
• L is Sb, As, Bi or P and R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , and R 9 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the Group VA element containing precursor is selected from the group consisting of: L[Si(SiR 1 R R 3 ) 3 ][Si(SiR 4 R s R 6 ) 3 ][Si(SiR 7 R 8 R 9 ) 3 ], L[Si(NR 1 R 2 ) 3 ][Si(NR 3 R 4 ) 3 ][Si(NR 5 R 6 ) 3 ], L[Si(OR 1 ) 3 ][Si(OR 2 ) 3 ][Si(OR 3 ) 3 ], and L[SiR 1 R 2 ][SiR 3 R 4 ][SiR 5 R 6 ] with a double bond between silicon and one of the R groups.
• the Sb precursor comprises: a ring or cyclical configuration comprising a Sb atom and multiple Si atoms; or comprises more than one Sb atom.
• L is Sb, As, Bi or P and R 1 , R 2 , R 3 , R 4 , R 5 and R 6 , are selected from the group consisting of alkyl, hydrogen, alkenyl, alkynyl, or aryl groups.
• L is selected from the group of consisting Sb, As, Bi or P.
• a partial structure of the precursor formula is represented below:
• the precursor contains multiple atoms of Si and L.
• L is selected from the group of consisting Sb, As, Bi or P.
• a partial structure of a precursor in one embodiment is represented below:
• Si and L atoms in the partial formulas pictured above can also be bound to one or more R groups.
• any of the R groups described herein can be used.
• the precursor contains a Si-L-Si bond structure in a cyclical or ring structure.
• L is selected from the group of consisting Sb, As, Bi or P.
• a partial structure of a precursor in one embodiment is represented below.
• the R group can comprise an alkyl, alkenyl, alkynyl, alkylsilyl, alkylamine or alkoxide group. In some embodiments the R group is substituted or branched. In some embodiments the R group is not substituted and/or is not branched.
• the Si and L atoms in the partial formula pictured above can also be bound to one or more R groups. L is selected from the group of consisting Sb, As, Bi or P. In some embodiments, any of the R groups described herein can be used.
• an additional precursor to be used in combination with the Group VA element containing precursors described herein is not an oxygen source.
• oxygen source comprises oxygen precursors, such as water, ozone, alcohol, oxygen atoms, oxygen plasma and oxygen radicals, typically used in ALD for depositing metal oxides.
• the other precursor is not water, ozone, or alcohol.
• plasma is not used.
• the other precursor to be used in combination with the Group VA element-containing precursors described herein can also contain the same Group VA element as the Group VA-element containing precursor, such that the deposited film is an elemental film comprising the Group VA element.
• the other precursor may be, for example, a halide of a Group VA element, such as chloride, fluoride, bromide or iodide.
• the other precursor is SbCl 3 or BiCl 3 and the films deposited are elemental Sb or elemental Bi films, respectively.
• any of the precursors disclosed herein can be used to deposit a thin film comprising a Group VA element.
• elemental Group VA elements are deposited.
• elemental Sb, As, Bi, or P is deposited.
• the deposited film comprising a Group VA element comprises one or more additional elements.
• a metal, non- metal, or metalloid can also be included in the deposited thin films comprising a Group VA element.
• the substrate temperature when depositing the thin film comprising a Group VA element is from about 20 °C to about 500 °C. In some embodiments the temperature is from about 50 °C to about 400 °C. In some embodiments the temperature is from about 50 °C to about 300 °C.
• the growth rate per cycle when depositing thin films comprising a Group VA element can vary based on the precursors used and the reactor process conditions.
• the growth rate per cycle as used herein refers to the average growth rate per cycle with the cycle including the provision of one pulse of two different reactants.
• the average growth rate per cycle is from about 0.05A/cycle to about 2.5 A/cycle.
• the average growth rate per cycle is from about 0.1 A/cycle to about 1.5 A/cycle.
• the average growth rate per cycle is from about 0.2A/cycle to about 1.0 A/cycle.
• Group VA element containing thin films are doped with one or more dopants selected but not limited to those from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi.
• N precursors disclosed herein can be used to deposit a thin film comprising N.
• the thin film does not comprise a transition metal.
• one or more elements in the thin films are selected from the group consisting of elements from Groups IIIA to VIA i.e. Groups 13 to 16 according to the IUPAC.
• one or more elements in the thin films are selected from the group consisting of N, B, Al, Ga and In.
• the thin films are selected from the group consisting of BN, A1N, GaN and InN.
• the thin film comprising N is deposited that is not SiN or does not contain Si or Ge.
• the deposited film comprising N comprises one or more additional elements.
• the deposited film comprising N is used for doping a phase change material, such as Ge-Sb-Te, with nitrogen.
• the precursor comprising N can be used in deposition cycles in combination with the Ge, Sb, and Te deposition cycles disclosed herein to deposit a thin film comprising Ge-Sb-Te doped with nitrogen.
• the substrate temperature when depositing the thin film comprising N is from about 20 °C to about 500 °C. In some embodiments the temperature is from about 50 °C to about 400 °C. In some embodiments the temperature is from about 50 °C to about 300 °C.
• the growth rate per cycle when depositing thin films comprising N can vary based on the precursors used and the reactor process conditions.
• the growth rate per cycle as used herein refers to the average growth rate per cycle with the cycle including the provision of one pulse of two different reactants.
• the average growth rate per cycle is from about 0.05A/cycle to about 2.5 A/cycle.
• the average growth rate per cycle is from about 0.1 A/cycle to about 1.5 A/cycle.
• the average growth rate per cycle is from about 0.2A/cycle to about 1.0 A/cycle.
• the N containing thin films are doped with one or more dopants selected but not limited to those from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi.
• the Group VA element containing precursor comprises a Group VA element bound to three tin (Sn) atoms.
• the Group VA element containing precursor can have a general formula of L(SnR R R ) 3 , wherein L is Sb, As, Bi or P, and R , R , and R are alkyl groups comprising one or more carbon atoms.
• the R , R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility,
• R , R and/or R can be hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• R 1 , R 2 , R 3 can be halogen atoms.
• the Group VA the Group VA
• element containing precursor have a general formula of L(SnR R R ) 3 , wherein L is Sb,
• R , R , and R are alkyl groups comprising one or more carbon atoms.
• the R , R , and R alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the VA precursor has a formula of In other embodiments the precursor is L(SnEt 3 ) 3 or L(SnMe 3 ) 3 .
• elemental antimony (Sb) films are deposited by ALD preferably without the use of plasma.
• ALD deposition cycles that deposit elemental antimony are useful in a variety of applications.
• antimony can be used in many applications including optical storage materials, semiconductor mixtures (compound, ternary, and quaternary mixtures) and non-volatile phase change memories.
• Sb precursors for use in an ALD process without plasma allows for deposition of elemental antimony.
• elemental antimony can be used as a phase change material.
• Sb deposition cycles can also be used in combination with deposition cycles of other materials. The ratio of cycles can be selected to control the stoichiometry, including Sb content, in the deposited film to achieve a film with a desired composition and structure.
• phase change memory films comprising Sb-Te, Ge-Sb-Te, and Ge-Sb can be deposited.
• FIG. 1 is a flow chart generally illustrating a method for forming a Sb thin film 10 in accordance with one embodiment.
• an elemental Sb thin film is formed on a substrate in a reaction chamber by an ALD type process comprising multiple Sb deposition cycles, each deposition cycle comprising: providing a first vapor phase reactant pulse comprising a first Sb precursor 11 into the reaction chamber to form no more than about a single molecular layer of the Sb precursor on the substrate;
• Each Sb deposition cycle typically forms at most about one monolayer of Sb.
• the Sb deposition cycle is repeated until a film of a desired thickness is formed 19.
• a Sb film of from about 10 A to about 2000 A, preferably from about 50 A to about 500 A is formed.
• the deposition cycle begins with provision of the first Sb precursor
• the deposition cycle begins with the provision of the second Sb precursor. It will be understood by the skilled artisan that provision of the first Sb precursor and second Sb precursor are interchangeable in the ALD cycle.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the first Sb precursor has a formula of SbX 3 , wherein X is a halogen element. More preferably the Sb source is SbCl 3 , SbBr 3 or Sbl 3 .
• the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors described herein is not an oxygen source.
• oxygen source refers to reactants that comprise oxygen, such as water, ozone, alcohol, oxygen atoms, oxygen plasma and oxygen radicals, typically used in ALD for depositing metal oxides.
• the other precursor is not water, ozone or alcohol.
• the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein is not an aminogermanium precursor, such as tetraaminogermanium or organotellurium precursor. In some embodiments the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein is not a chalcogenide precursor. In some embodiments the other reactant to be used in combination with the Sb(SiR'R 2 R 3 ) 3 precursors disclosed herein does not contain plasma or an excited species.
• the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein does not contain nitrogen. In some embodiments the other reactant to be used in combination with the Sb(SiR 1 R2 R 3 ) 3 precursors disclosed herein is not an alkoxide substituted precursor. In some embodiments the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein is not an amino substituted precursor. In some embodiments the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein is not an alkyl substituted precursor. In some embodiments the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein does not contain a direct Sb-C bond.
• the Sb, As, Bi, N and P center atoms of the Sb, As, Bi, N and P precursors disclosed herein can be bonded to Si, Ge, or Sn atoms.
• Sb, As, Bi, N and P are more electronegative than Si, Ge or Sn, which will create polarity in bonds and thus a partial negative charge on the Sb, As, Bi, N and P center atoms of the Sb, As, Bi, N and P precursors disclosed herein.
• the Sb, As, Bi, N and P center atoms can have a negative oxidation state.
• the slight partial negative charge of the center atom in the precursors disclosed herein for example the slight partial negative charge of As in As(SiEt 3 ) 3 or Sb in Sb(SiEt 3 ) 3
• the partial positive charge of the center atom in the other precursor for example the partial positive charge of Ga in GaCl 3 or Sb in SbCl 3
• the precursor combination successful and film deposition for example Ga-As or Sb film deposition, possible.
• the other reactant to be used in combination with the Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein is not a reducing agent, such as hydrogen, H 2 /plasma, amine, imine, hydrazine, silane, silyl chalcogenide, germane, ammonia, alkane, alkene or alkyne.
• a reducing agent refers to a compound capable of reducing an atom of the other reactant, usually the atom which will be deposited in the film in an ALD process and sometimes to elemental form. At the same time the reducing agent can be oxidized.
• the Sb(SiR R R ) 3 precursors disclosed herein acts as a reducing agent in an ALD process.
• the other reactant to be used in combination with Sb(SiR 1 R 2 R 3 ) 3 precursors disclosed herein is an oxidizing precursor, such as SbCl 3 .
• the oxidizing precursor is not water, alcohol or ozone.
• an oxidizing precursor is a precursor, which has a partial positive charge in the center atom of the molecule, such as Sb in case of SbCl 3 or Ga in case of GaCl 3 , and thus center atoms can be considered to have positive oxidation states. .
• the partial positive charge of the oxidizing precursors will be decreased in the deposited film i.e. the center atom of the molecule can be considered to be somewhat reduced although no real oxidation state increase has happened.
• the antimony deposition cycle only uses two reactive compounds.
• the second reactant is a Sb precursor with a formula of Sb(SiR R R ) 3 , wherein R , R , and R are alkyl groups comprising one or more carbon atoms.
• R 1 , R 2 , and R 3 alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the first Sb precursor is SbCl 3 and the second Sb precursor is Sb(SiEt 3 ) 3 .
• the substrate temperature during forming the Sb thin film deposition is preferably less than 250°C and more preferably less than 200°C and even more preferably below 150°C.
• Pressure of the reactor can vary much depending from the reactor used for the depositions. Typically reactor pressures are below normal ambient pressure.
• the skilled artisan can determine the optimal reactant evaporation temperatures based on the properties of the selected precursors.
• the evaporation temperatures for the second Sb precursor, such as Sb(SiEt 3 ) 3 which can be synthesized by the methods described herein, is typically about 85°C.
• the evaporation temperature for the first Sb precursor, such as SbCl 3 is typically about 30°C to 35°C.
• the skilled artisan can determine the optimal reactant pulse times through routine experimentation based on the properties of the selected precursors and the desired properties of the deposited Sb thin film.
• the first and second Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds, and most preferably about 1 to 2 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds, and most preferably 1 to 2 seconds in length.
• the growth rate of the elemental Sb thin films will vary depending on the reaction conditions. As described below, in initial experiments, the growth rate varied between about 0.3 and about 0.5 A/cycle.
• a Sb thin film is deposited on a substrate and forms the active material in a PCM cell.
• the Sb thin film is deposited on a substrate and used in a super-RENS device.
• the Sb thin film preferably has a thickness of about 10 A to about 2000 A.
• one or more dopants selected from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi, but not limited to those, is introduced into film.
• the precursor comprising dopant reacts preferably, but not necessarily, with the Sb precursors described herein.
• Elemental Sb thin films were formed using alternating and sequential pulses of SbCl 3 and Sb(SiEt 3 ) 3 . 1000 cycles were applied.
• the elemental Sb thin films were formed on soda lime glass and silicon substrates with native oxide.
• Sb(SiEt 3 ) 3 is a liquid at room temperature and was evaporated from an open boat at a temperature of 85°C. The substrate temperature during deposition was 95°C.
• the pulse and purge length for the SbCl 3 precursor was 1 second and 2 seconds, respectively.
• the pulse length for Sb(SiEt 3 )3 was varied between 0.5 and 2.0 seconds, with a purge length of 2 seconds.
• FIG. 3 shows the average growth rate per cycle for Sb films deposited at 0.5, 1.0, and 2.0 second pulse lengths of (Et 3 Si) 3 Sb.
• FIG. 3 shows a maximum growth rate of around 0.45 A/cycle.
• the antimony films were clear and mirror like as deposited.
• FIG. 4 shows a gracing incidence XRD (GIXRD) pattern of the Sb film deposited as described in reference to FIG. 3 using a 1 second (Et 3 Si) 3 Sb pulse length.
• GIXRD gracing incidence XRD
• the GIXRD pattern shows a polycrystalline Sb film with all of the reflections identified as rhombohedral Sb (iron black, PDF 00-035-0732).
• the deposited film was also studied by energy dispersive x-ray (EDX) measurement.
• EDX energy dispersive x-ray
• the precursors used for ALD in combination with the Sb, As, Bi, and P precursors disclosed herein includes precursors that will react on the surface with the adsorbed Sb, As, Bi, and P precursors disclosed herein.
• a multi-component film such as a Ge-Sb-Te film, may comprise multiple deposition cycles for different binary materials, such as in the case of GST, using Ge-Te cycles, Sb-Te cycles, and optionally Sb deposition cycles.
• Such multi-component materials may contain other precursors than precursors described herein, which are not favorable to use directly in the same cycle with the Sb, As, Bi, and P precursors disclosed herein, but are favorable to use in a multi- component material process in other cycles.
• Sb, As, Bi, and P precursors disclosed herein are used in an ALD reaction with an other reactant that is not water, alcohol or ozone.
• the reactant used for ALD in combination with Sb, As, Bi, and P precursors disclosed herein is not an aminogermanium precursor, such as tetraaminogermanium or an organotellurium precursor.
• the other reactant to be used in combination with the Sb, As, Bi, and P precursors disclosed herein is not a chalcogenide precursor.
• the precursors used for ALD in combination with the Sb, As, Bi, and P precursors disclosed herein do not contain plasma.
• the precursors used for ALD in combination with the Sb, As, Bi, and P precursors disclosed herein do not contain nitrogen.
• the other reactant to be used in combination with the Sb, As, Bi, and P precursors disclosed herein is not an alkoxide substituted precursor.
• the other reactant to be used in combination with the Sb, As, Bi, and P precursors disclosed herein is not an amino substituted precursor.
• the other reactant to be used in combination with the Sb, As, Bi, and P precursors disclosed herein is not an alkyl substituted precursor.
• the precursors used for ALD in combination with the Sb, As, Bi, and P precursors disclosed herein are not reducing precursors, such as hydrogen, H 2 /plasma, amine, imines, hydrazine, silane, silyl chalcogenide, germane, ammonia, alkane, alkene or alkyne.
• the Sb, As, Bi, and P precursors disclosed herein act as a reducing agent in an ALD process.
• the precursor used for ALD in combination with the Sb, As, Bi, and P precursors disclosed herein is an oxidizing precursor, such as SbCl 3 .
• the oxidizing precursor does not contain oxygen.
• the oxidizing precursor is not alcohol, water, or ozone.
• the metal precursor is metal-organic or organometallic precursor. In some embodiments the metal precursor is a metal-organic or organometallic precursor, which does not contain nitrogen. In some embodiments the metal precursor is a halide precursor. In some embodiments the metal precursor is a halide precursor and does not contain any organic groups as ligands. In some embodiments the metal precursor contains only fluorides or chlorides, preferably chlorides, as ligands. In some embodiments the metal precursor is an adduct precursor.
• Adducts are not considered as a ligands and adducted precursor can organic groups as adducts without having organic groups as ligands, for example, here it is considered that GeCl 2 -dioxane does not have any organic groups as ligands.
• Ligands are groups or atoms which are directly bonded with the center atom.
• the reactants are selected such that a dehalosilylation reaction occurs between the reactants.
• a metal precursor is selected so that a dehalosilylation reaction occurs between the metal reactant and a Sb, As, Bi, or P precursor disclosed herein in an ALD processes.
• the metal precursor is selected so that a comproportionation reaction occurs between the metal reactant and a Sb, As, Bi, or P precursor disclosed herein in an ALD process.
• Preferred precursors include, but are not limited to metal halides, alkyls, alkoxides, amides, silylamides, amidinates, cyclopentadienyls, carboxylates, betadiketonates and betadiketoimines.
• Preferred metals in metal precursors include, but are not limited to Ga, Al, Ge, Bi, Zn, Cu, In, Ag, Au, Pb, Cd, Hg, Sn, Co, Ni, Si.
• the preferred metal can possibly be rare earth or alkaline rare earth metal.
• More preferred Sb precursors include, any of the Sb precursors described herein and Sb halides, such as SbCl 3 , SbBr 3 and Sbl 3 , Sb alkoxides, such as Sb(OEt) 3 and Sb amides.
• Ge precursors include Ge halides, such as GeCl 2 and GeBr 2 , adducted derivatives of GeCl 2 , GeF 2 and GeBr 2 , such as GeCl 2 -dioxane.
• Ge halides such as GeCl 2 and GeBr 2
• adducted derivatives of GeCl 2 , GeF 2 and GeBr 2 such as GeCl 2 -dioxane.
• the oxidation state of Ge is +11.
• More preferred Al precursors include Al halides, such as A1C1 3 , and Al alkyls, such as trimethylaluminum (TMA).
• Al halides such as A1C1 3
• Al alkyls such as trimethylaluminum (TMA).
• More preferred Bi precursors include Bi halides, such as BiCl 3 .
• More preferred Ga precursors include Ga halides, such as GaCl 3 , and Ga alkyls, such as trimethylgallium (TMG) .
• Ga halides such as GaCl 3
• Ga alkyls such as trimethylgallium (TMG) .
• More preferred Zn precursors include elemental Zn, Zn halides, such as ZnCl 2 , and alkyl zinc compounds such Zn(Et) 2 or Zn(Me) 2 .
• More preferred Cu compounds include Cu carboxylates, such as Cu(II)-pivalate, Cu halide, such as CuCl or CuCl 2 , Cu betadiketonates, such as Cu(acac) 2 or Cu(thd) 2 and Cu-amidinates.
• Cu carboxylates such as Cu(II)-pivalate
• Cu halide such as CuCl or CuCl 2
• Cu betadiketonates such as Cu(acac) 2 or Cu(thd) 2 and Cu-amidinates.
• More preferred In compounds include In halides, such as InCl 3 and In alkyl compounds, such as In(CH 3 ) 3 .
• More preferred Pb compounds include Pb alkyls, such as tetraphenyl lead Ph 4 Pb or tetraethyl lead EtjPb.
• More preferred Si precursors include Si halides, such as SiCl 4 , and aminosilanes.
• More preferred Sn precursors include Sn halides, such as SnCl 4 .
• Ni precursors include metalorganic Ni compounds, such as Ni(acac) 2 or Ni(Cp) 2 .
• More preferred Co precursors include metalorganic Co compounds, such as Co(acac) 2 or Co(thd) 2 .
• Metal precursors can be used with the precursors comprising nitrogen that are disclosed herein to deposit thin films comprising nitrogen.
• the metal precursor does not comprise a transition metal i.e. a metal selected from Groups 3 through 12 according to the IUPAC. In some embodiments the metal precursor does not comprise Si or Ge. In some embodiments the metal precursor comprises Al, B, Ga, In, Sn or Pb.
• the metal precursor is a metal-organic or organometallic precursor. In some embodiments the metal precursor is a halide precursor. In some embodiments the metal precursor is a halide precursor and does not contain any organic groups as ligands. In some embodiments the metal precursor contains only fluorides or chlorides, preferably chlorides, as ligands. In some embodiments the metal precursor is an adduct precursor.
• Preferred precursors include, but are not limited to metal halides, alkyls, alkoxides, amides, silylamides, amidinates, cyclopentadienyls, carboxylates, betadiketonates and betadiketoimines, wherein the metal is not a transition metal.
• More preferred Al precursors include Al halides, such as A1C1 3 , and Al alkyls, such as trimethylaluminum (TMA).
• Al halides such as A1C1 3
• Al alkyls such as trimethylaluminum (TMA).
• More preferred Ga precursors include Ga halides, such as GaCl 3 , and Ga alkyls, such as trimethylgallium (TMG).
• Ga halides such as GaCl 3
• Ga alkyls such as trimethylgallium (TMG).
• More preferred In compounds include In halides, such as InCl 3 and In alkyl compounds, such as In(CH 3 ) 3 .
• More preferred Pb compounds include Pb alkyls, such as tetraphenyl lead PhjPb or tetraethyl lead EtPb.
• More preferred Sn precursors include Sn halides, such as SnCl 4 . Te and Se precursors for atomic layer deposition
• Te and Se precursors are disclosed in U.S. Application Serial No. 12/429,133 filed April 23, 2009 entitled “Synthesis and Use of Precursors for ALD of Tellurium and Selenium Thin Films". The disclosure of which is incorporated by reference herein in its entirety.
• any of the following precursors can be used in the various ALD processes disclosed herein.
• precursors comprising Te and Se are disclosed.
• the Te or Se precursor has Te or Se bound to two silicon atoms.
• it can have a general formula of A(SiR 1 R 2 R 3 ) 2 , wherein A is Te or Se and R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• the R 1 , R 2 , and R 3 alkyl groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• R 1 , R 2 and/or R 3 can be hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 can be any organic groups containing heteroatoms, such as N, O, F, Si, P, S, CI, Br or I. In some embodiments R 1 , R 2 , R 3 can be halogen atoms.
• the Te precursor is TeCSiMe ⁇ Bu and the Se precursor is Se(SiMe 2 l Bu) 2 . In other embodiments the precursor is Te(SiEt 3 ) 2 ,Te(SiMe 3 ) 2 , Se(SiEt 3 ) 2 or Se(SiMe 3 ) 2 . In more preferred embodiments the precursor has a Te-Si or Se-Si bond and most preferably Si-Te-Si or Si-Se-Si bond structure.
• the Te or Se precursor has a general formula of [R ⁇ R ⁇ k-Si-A-Si-rx R ⁇ wherein A is Te or Se; and wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 , can be independently selected to be alkyl, hydrogen, alkenyl, alkynyl or aryl groups.
• R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be any organic groups containing also heteroatoms, such as N, O, F, Si, P, S, CI, Br or I.
• R 1 , R 2 , R 3 , R 4 , R 5 and R 6 can be halogen atoms.
• X 1 and X 2 can be Si, N, or O.
• X and X are different elements.
• Si when X is Si then Si will be bound to three R groups, for example [R R R Si] 3 -Si-A-Si- [SiR 4 R 5 R 6 ] 3 .
• nitrogen will only be bound to two R groups ([R 1 R 2 N]3-Si-A-Si-[NR 3 R 4 ] 3 ).
• R 1 , R 2 , R 3 , R 4 , R 5 and R 6 groups can be selected independently of each other in each ligand based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc
• the Te or Se precursors is selected from the group consisting of: R ⁇ R ⁇ i-Si-A-Si-SiR ⁇ R 6 ; R ⁇ N-Si-A-Si-NR ⁇ 4 ; R'-O-Si-A-Si- O-R 2 ; or R ! R 2 Si-A-SiR 3 R 4 with a double bond between silicon and one of the R groups.
• the Te or Se precursor comprises: a ring or cyclical configuration comprising a Te or Se atom and multiple Si atoms; or comprises more than one Te atoms or more than one Se atoms.
• A is Te or Se and R 1 , R 2 , R 3 , R 4 , R 5 and R 6 , are selected from the group consisting of alkyl, hydrogen, alkenyl, alkynyl, or aryl
• the Te or Se precursor is not A(SiR R R ) 2 .
• a partial structure of the precursor formula is represented below:
• the precursor contains multiple atoms of Si and Te or Se.
• A is Te or Se:
• Si atoms in the partial formula pictured above can also be bound to one or more R groups.
• any of the R groups described herein can be used.
• the precursor contains a Si-Te-Si or Si-Se-Si bond structure in a cyclical or ring structure.
• a partial structure of a precursor in one embodiment is represented below, wherein A is Te or Se.
• the R group can comprise an alkyl, alkenyl, alkynyl, alkylsilyl, alkylamine or alkoxide group. In some embodiments the R group is substituted or branched. In some embodiments the R group is not substituted and/or is not branched.
• the Si atoms in the partial formula pictured above can also be bound to one or more R groups. In some embodiments, any of the R groups described herein can be used.
• Sb-Te, preferably Sb 2 Te 3 , films are deposited by ALD preferably without the use of plasma, however in some cases plasma might be used, if needed.
• plasma such as hydrogen plasma, hydrogen radicals or atomic hydrogen, may be used.
• Another use for plasma is doping of the films, for example doping by O, N or Si may be done using plasma.
• an Sb 2 Te 3 thin film is formed on a substrate in a reaction chamber by an ALD type process comprising multiple Sb-Te deposition cycles, each deposition cycle comprising:
• a first vapor phase reactant pulse comprising a Sb precursor into the reaction chamber to form no more than about a single molecular layer of the Sb precursor on the substrate;
• each Sb-Te deposition cycle typically forms at most about one monolayer of Sb 2 Te 3 .
• the Sb-Te deposition cycle is repeated until a film of a desired thickness is formed.
• the deposition cycle begins with provision of the Sb precursor, in other embodiments the deposition cycle begins with the provision of the Te precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Te or Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the Sb source is SbX 3 , wherein X is a halogen element. More preferably the Sb source is SbCl 3 or Sbl 3 .
• the Te precursor has a formula of Te(SiR R R ) 2 , wherein
• R 1 , R2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• the R 1 , R2 , and R 3 alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the Te precursor is Te(SiMe 2 Bu) 2 .
• the precursor is Te(SiEt 3 ) 2 or Te(SiMe 3 ) 2 .
• the Te precursor is Te(SiEt 3 ) 2 and the Sb precursor is SbCl 3 .
• one or more dopants selected from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi, but not limited to those, is introduced into film.
• the precursor comprising dopant reacts preferably, but not necessarily, with the Te precursors described herein.
• Sb x Te y films having a desired composition can be deposited using Sb and Sb-Te cycles.
• the ratio of Sb-Te to the total number of cycles can be varied such that a Sb x Te y film is deposited with a desired composition.
• the variables x and y can be expressed as atomic ratios, atomic percentage, or the atomic composition per molecule. The units of expression of x and y should be apparent to the skilled artisan.
• the ratio of Sb cycles to Sb-Te cycles is between about 1 :100 and 100:1.
• the ratio of Sb-Te cycles to Sb and Sb-Te cycles is selected to deposit an Sb x Te y thin film having a desired composition.
• Sb 2 Te 3 is deposited.
• x is preferably between about 30% and about 50%. In some embodiments, x preferably is between about 35% and 45%.
• y is preferably between about 50% and 70%. In some embodiments, y is preferably between about 55% and 65%.
• x is preferably about 2. In some embodiments, y is between 0 and about 3. In some embodiments, x is 2 and y is 1. In some embodiments the Sb film is doped with Te and therefore the y is from about 1 % to about 10 % and x is from about 99 % to 90 %, respectively,
• the Sb-Te thin film is crystalline as deposited. In some embodiments, the Sb-Te thin film can be amorphous as deposited. In some embodiments, the thin film can be annealed to convert an amorphous thin film to a crystalline thin film.
• any of the process conditions described herein can be used.
• the reactants, reactant flow rates and concentrations, temperature, etc. described herein can be used for the Sb or Sb-Te deposition cycles.
• one or more dopants selected from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi, but not limited to those, is introduced into Sb-Te film.
• the Sb-Te film is doped with Ag and In and have a composition of approximately Ago.o5 5 Ino.o 65 Sb 0 . 5 9Te 0 .29.
• Sb x Te y films were grown using Sb deposition cycles and Sb 2 Te 3 deposition cycles.
• the substrate temperature was about 95°C during the deposition cycles.
• Sb 2 Te 3 was deposited with SbCl 3 and Te(SiEt 3 ) 2 using a deposition cycle comprising:
• Sb was deposited by a Sb deposition cycle with SbCl 3 and Sb(SiEt 3 ) 3 comprising:
• FIG. 5 shows the composition of the deposited films versus the ratio of
• FIG. 5 shows two linear regions with different slopes.
• the first region has a first slope for ratios from 0 to about 0.66.
• the slope changes for the second linear region for cycle ratios from about 0.66 to 1.
• the data in FIG. 5 indicates that the composition of the deposited Sb-Te film can be tailored based on the ratio of Sb cycles to St3 ⁇ 4Te 3 cycles.
• FIG. 6 illustrates the average growth rate per cycle versus the ratio of Sb 2 Te 3 cycles to the total number of Sb and Sb 2 Te 3 cycles.
• the average growth rate for the Sb deposition cycle is about 0.45 A/cycle.
• the average growth rate for a Sb 2 Te 3 deposition cycle is about 0.15 A/cycle.
• FIG. 6 illustrates that the average growth rate per cycle approaches the 83 ⁇ 4 ⁇ 3 growth rate per cycle for a cycle ratio of about 0.66.
• FIG. 7 illustrates GIXRD data for Sb-Te films of varying compositions, including Sb 70 Te 30 , Sb 83 Te 17 , and Sb 86 Tej 4 . All three films illustrated in FIG. 7 were crystalline. No chlorine was detected by EDX measurements of the deposited films.
• a Ge x Sb y thin film is formed by ALD without the use of plasma.
• FIG. 2 is a flow chart generally illustrating a method for forming a Ge- Sb thin film 20 in accordance with one embodiment.
• a Ge-Sb thin film is formed on a substrate by an ALD type process comprising multiple Ge-Sb deposition cycles, each deposition cycle comprising:
• Ge-Sb deposition cycle This can be referred to as the Ge-Sb deposition cycle.
• Each Ge-Sb deposition cycle typically forms at most about one monolayer of Ge-Sb.
• the Ge-Sb deposition cycle is repeated until a film of a desired thickness is formed 29. In some embodiments a Ge-Sb film of from about 10 A to about 2000 A is formed.
• the x and y values and composition of the Ge x Sb y film can vary. In some embodiments, x and y are less than 1. In some embodiments, the sum of x and y is equal to about 1, or 100 if the x and y values are expressed as a percentage.
• the deposition cycle begins with provision of the Ge precursor, in other embodiments the deposition cycle begins with the provision of the Sb precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Ge or Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the Ge source is GeX 2 or GeX 4 , wherein X is a halogen element.
• X is a halogen element.
• the oxidation state of Ge is +11.
• the Ge source is GeBr 2 .
• the Ge source is germanium halide with coordinating ligands, such as dioxane ligands.
• the Ge source with coordinating ligands is germanium dihalide complex, more preferably a germanium dichloride dioxane complex GeCl 2 -C 4 H 8 0 2 .
• the Sb precursor can be any of the Sb precursors described herein.
• the second Sb precursor has a formula of Sb(SiR 1 R 2 R 3 ) 2 , wherein R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• R 1 , R 2 , and R 3 alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the substrate temperature during forming the Ge-Sb thin film is preferably less than 250°C and more preferably less than 200°C and even more preferably below 100°C. If an amorphous thin film is desired the temperature can be lowered even further down to at or below about 90°C. In some embodiments the deposition temperature can be below about 80°C, below about 70°C, or even below about 60°C.
• the Ge and Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds, and most preferably about 1 to 4 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds, In some cases like in batch ALD reactors the pulse and purge times can vary much more and longer pulse times may be used even in order of minutes.
• the deposited Ge-Sb thin films are amorphous. In some embodiments, the deposited Ge-Sb thin films are crystalline.
• the deposited Ge-Sb film can be annealed.
• Ge-Sb films were deposited on substrates at approximately 95°C using Sb(SiEt 3 ) 3 as the Sb source and GeCl 2 -C 4 H 8 0 2 as the Ge source, using a deposition cycle comprising:
• the growth rate per cycle was calculated at about 0.23 A/cycle.
• X-ray diffractogram results indicated that the deposited film was amorphous.
• Energy dispersive x-ray (EDX) analysis showed that the deposited film was Ge 0.82 Sb 0.18 (82 at% Ge and 18 at% Sb).
• Ge x Sb y films having a desired composition can be deposited using Sb and Ge-Sb cycles.
• the ratio of Ge-Sb to the total number of cycles can be varied such that a Ge x Sb y film is deposited with a desired composition.
• the variables x and y can be expressed as atomic ratios, atomic percentage, or the atomic composition per molecule. The units of expression of x and y should be apparent to the skilled artisan.
• the ratio of Sb to Ge-Sb cycles is between about 1 :100 and 100:1.
• the ratio of Sb to Sb and Ge-Sb is selected to deposit a Ge- Sb thin film having a desired composition.
• x is preferably between about 5% and about 20%. In some embodiments, y is preferably between about 80% and 95%. In one embodiment, a film with eutectic composition, Ge 15 Sb 8 5, is deposited. In some embodiments the Sb film is doped with Ge and therefore the y is from about 1 % to about 10 % and x is from about 99 % to 90 %, respectively.
• the Ge-Sb thin film is crystalline as deposited. In some embodiments, the Ge-Sb thin film can be amorphous as deposited. In some embodiments, the thin film can be annealed to convert an amorphous thin film to a crystalline thin film.
• any of the process conditions described herein can be used.
• the reactants, reactant flow rates and concentrations, temperature, etc. described herein can be used for the Sb or Ge-Sb deposition cycles.
• Example 4 one or more dopants selected from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi, but not limited to those, is introduced into film.
• Ge-Sb films of varying compositions were deposited using Sb deposition cycles and Ge-Sb deposition cycles.
• the Sb was deposited by a Sb deposition cycle using SbCl 3 and Sb(SiEt 3 ) 3 comprising:
• the Ge-Sb films were deposited using Sb(SiEt 3 ) 3 as the Sb source and GeCl 2 -C 4 H 8 0 2 as the Ge source, using a deposition cycle comprising:
• FIGS. 8 and 9 illustrate composition and growth rate for the deposited Ge-Sb films versus the ratio of Ge-Sb cycles to the total number of cycles.
• FIG. 8 illustrates a linear relationship between the ratios of Ge-Sb cycles to total number of cycles versus composition of the deposited film.
• FIG. 9 also illustrates a linear relationship between the average growth rate per cycle and the ratio of Ge-Sb cycles to total cycles.
• the Ge 0.23 Sb 0.77 and Ge 0 82 Sbo .18 films were characterized by EDX analysis.
• the Ge 0.23 Sb 0.77 and Geo .82 Sb 0. i 8 films were amorphous as deposited.
• EDX analysis also found that some chlorine was present in the deposited Ge-Sb films.
• the amount of chlorine increased with the amount of Ge present in the deposited film. It is likely that the chlorine comes from the GeCl 2 -C 4 H 8 0 2 precursor.
• the chlorine contribution from the GeCl 2 -C 4 H 8 0 2 precursor may not adversely affect device performance.
• Ge x Sb y Te z (GST) thin films are formed on a substrate by an ALD type process comprising multiple deposition cycles.
• Sb, Te and Ge deposition cycles are provided to deposit a GST thin film with a desired stoichiometry and desired thickness.
• the particular ratio and order of cycles can be selected to achieve a thin film having a desired composition
• Sb, Sb-Te, Ge-Te deposition cycles are provided to deposit a GST thin film with a desired stoichiometry and desired thickness.
• the particular ratio and order of cycles can be selected to achieve the desired composition.
• Sb, Sb-Te, Ge-Te and Ge-Sb deposition cycles are provided to deposit a GST thin film with a desired stoichiometry and desired thickness.
• the particular ratio and order of cycles can be selected to achieve the desired composition.
• a GST thin film having the formula Ge 2 Sb 2 Te 5 is deposited.
• an Sb rich GST film, such as Ge 3 Sb 6 Te 5j is deposited.
• a thin film having the formula GeSb 2 Te 4 is deposited.
• a thin film having the formula GeSb 4 Te 7 is deposited.
• the GST deposition process begins with a Sb deposition cycle and in other embodiments the GST deposition process begins with an Sb-Te deposition cycle, Ge-Te or Ge-Sb cycle.
• multiple Sb deposition cycles can be performed consecutively prior to a Sb-Te or Ge-Sb cycle
• multiple Sb-Te deposition cycles can be performed consecutively prior to a subsequent Sb or Ge-Sb deposition cycle
• multiple Ge-Sb deposition cycles can be performed consecutively prior to a subsequent Sb, Ge-Te or Sb-Te deposition cycle.
• any of the process conditions described herein can be used.
• the reactants, reactant flow rates and concentrations, temperature, etc. described herein can be used for the Sb, Ge-Sb, Sb-Te, Ge-Te deposition cycles.
• the GST thin film can be crystalline as deposited.
• an amorphous GST thin film is deposited.
• the amorphous thin film can be annealed in the presence of an inert gas, such as nitrogen.
• the substrate and thin film can also be heated during the annealing step at a temperature above the deposition temperature.
• the substrate temperature during the annealing step is above about 130°C.
• the substrate temperature during the annealing step is above about 250°C. Most preferably the temperature during the annealing step is above 300°C.
• the annealing step can change the crystallinity of the thin film. In some embodiments an amorphous thin film can crystallize during the annealing step. In some embodiments the crystallinity of a crystalline GST thin film can change during the annealing step.
• Ge x Sb y Se z thin films are formed on a substrate by an ALD type process comprising multiple deposition cycles.
• Sb, Sb-Se, Ge-Se and Ge-Sb deposition cycles are provided to deposit a thin film with a desired stoichiometry and desired thickness.
• the particular ratio and order of cycles can be selected to achieve the desired composition.
• the Sb, Sb-Se, Ge-Se and Ge-Sb deposition cycles can be performed in any order.
• the deposition process begins with a Sb deposition cycle and in other embodiments the deposition process begins with an Sb-Se deposition cycle, Ge-Se or Ge-Sb cycle.
• multiple Sb deposition cycles can be performed consecutively prior to a Sb-Se or Ge-Sb cycle
• multiple Sb-Se deposition cycles can be performed consecutively prior to a subsequent Sb or Ge-Sb deposition cycle
• multiple Ge-Sb deposition cycles can be performed consecutively prior to a subsequent Sb, Ge-Se or Sb-Se deposition cycle.
• any of the process conditions described herein can be used.
• the reactants, reactant flow rates and concentrations, temperature, etc. described herein can be used for the Sb, Ge-Sb, Sb-Se, and Ge-Se deposition cycles.
• the thin film can be crystalline as deposited.
• an amorphous thin film is deposited.
• the amorphous thin film can be annealed in the presence of an inert gas, such as nitrogen.
• the substrate and thin film can also be heated during the annealing step at a temperature above the deposition temperature.
• the substrate temperature during the annealing step is above about 130°C.
• the substrate temperature during the annealing step is above about 250°C. Most preferably the temperature during the annealing step is above 300°C.
• the annealing step can change the crystallinity of the thin film. In some embodiments an amorphous thin film can crystallize during the annealing step. In some embodiments the crystallinity of a crystalline thin film can change during the annealing step.
• a Al x Sb y thin film is formed by ALD without the use of plasma.
• An Al-Sb thin film is formed on a substrate by an ALD type process comprising multiple Al-Sb deposition cycles, each deposition cycle comprising:
• a first vapor phase reactant pulse comprising a Al precursor into the reaction chamber to form no more than about a single molecular layer of the Al precursor on the substrate;
• a second vapor phase reactant pulse comprising a Sb precursor to the reaction chamber such that the Sb precursor reacts with the Al precursor on the substrate;
• Al-Sb deposition cycle This can be referred to as the Al-Sb deposition cycle.
• Each Al-Sb deposition cycle typically forms at most about one monolayer of Al-Sb.
• the Al-Sb deposition cycle is repeated until a film of a desired thickness is formed. In some embodiments a Al-Sb film of from about 10 A to about 2000 A is formed.
• the x and y values and composition of the Al x Sb y film can vary. In some embodiments, x and y are less than 1. In some embodiments, the sum of x and y is equal to about 1, or 100 if the x and y values are expressed as a percentage. [0281] Although the illustrated Al-Sb deposition cycle begins with provision of the Al precursor, in other embodiments the deposition cycle begins with the provision of the Sb precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Al or Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the Al source is A1X 3 , wherein X is a halogen element.
• the Al source is A1C1 3 .
• Al source is aluminum alkyl compound, such as trimethylaluminum (TMA).
• the Sb precursor can be any of the Sb precursors described herein.
• the second Sb precursor has a formula of Sb(SiR I R 2 R 3 )3, wherein R 1 , R 2 , and R are alkyl groups comprising one or more carbon atoms.
• R , R , and R alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the substrate temperature during forming the Al-Sb thin film is preferably less than 500°C and more preferably less than 350°C and even more preferably below 200°C. If an amorphous thin film is desired the temperature can be lowered even further down to at or below about 90°C. In some embodiments the deposition temperature can be below about 80°C, below about 70°C, or even below about 60°C.
• the Al and Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds.
• the pulse and purge times can vary much more and longer pulse times may be used even in order of minutes
• the deposited Al-Sb thin films are amorphous. In some embodiments, the deposited Al-Sb thin films are crystalline.
• the deposited Al-Sb film can be annealed.
• a In x Sb y thin film is formed by ALD without the use of plasma.
• An In-Sb thin film is formed on a substrate by an ALD type process comprising multiple In-Sb deposition cycles, each deposition cycle comprising:
• a first vapor phase reactant pulse comprising a In precursor into the reaction chamber to form no more than about a single molecular layer of the In precursor on the substrate;
• Each In-Sb deposition cycle typically forms at most about one monolayer of In-Sb.
• the In-Sb deposition cycle is repeated until a film of a desired thickness is formed. In some embodiments a In-Sb film of from about 10 A to about 2000 A is formed.
• the x and y values and composition of the In x Sb y film can vary. In some embodiments, x and y are less than 1. In some embodiments, the sum of x and y is equal to about 1, or 100 if the x and y values are expressed as a percentage.
• the deposition cycle begins with provision of the In precursor
• the deposition cycle begins with the provision of the Sb precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of In or Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the In source is InX 3 , wherein X is a halogen element.
• the In source is InCl 3 .
• In source is indium alkyl compound, such as trimethylindium (TMI).
• TMI trimethylindium
• the In source is an indium betadiketonate, such as indium acetylacetonate In(acac) 3 .
• the In source is InCp or a substituted Cp-derivative thereof.
• the Sb precursor can be any of the Sb precursors described herein.
• the second Sb precursor has a formula of Sb(SiR'R 2 R 3 ) 3 , wherein R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• R 1 , R 2 , and R 3 alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the substrate temperature during forming the In-Sb thin film is preferably less than 500°C and more preferably less than 350°C and even more preferably below 200°C. If an amorphous thin film is desired the temperature can be lowered even further down to at or below about 90°C. In some embodiments the deposition temperature can be below about 80°C, below about 70°C, or even below about 60°C.
• the In and Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds.
• the pulse and purge times can vary much more and longer pulse times may be used even in order of minutes.
• the deposited In-Sb thin films are amorphous. In some embodiments, the deposited In-Sb thin films are crystalline.
• the deposited In-Sb film can be annealed.
• a Ga x Sb y thin film is formed by ALD without the use of plasma.
• An Ga-Sb thin film is formed on a substrate by an ALD type process comprising multiple Ga-Sb deposition cycles, each deposition cycle comprising:
• Ga precursor on the substrate removing excess first reactant from the reaction chamber; providing a second vapor phase reactant pulse comprising a Sb precursor to the reaction chamber such that the Sb precursor reacts with the Ga precursor on the substrate; and
• Ga-Sb deposition cycle This can be referred to as the Ga-Sb deposition cycle.
• Each Ga-Sb deposition cycle typically forms at most about one monolayer of Ga-Sb.
• the Ga-Sb deposition cycle is repeated until a film of a desired thickness is formed. In some embodiments a Ga-Sb film of from about 10 A to about 2000 A is formed.
• the x and y values and composition of the Ga x Sb y film can vary. In some embodiments, x and y are less than 1. In some embodiments, the sum of x and y is equal to about 1, or 100 if the x and y values are expressed as a percentage.
• the illustrated Ga-Sb deposition cycle begins with provision of the Ga precursor
• the deposition cycle begins with the provision of the Sb precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Ga or Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the Ga source is GaX 3 , wherein X is a halogen element.
• the Ga source is GaCl 3 .
• Ga source is gallium alkyl compound, such as trimethylgallium (TMG).
• TMG trimethylgallium
• the Ga source is a gallium betadiketonate.
• the Sb precursor can be any of the Sb precursors described herein.
• the second Sb precursor has a formula of Sb(SiR 1 R 2 R 3 ) 3 , wherein R 1 , R 2 , and R 3 are alkyl groups comprising one or more carbon atoms.
• R 1 , R 2 , and R 3 alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc. .
• the substrate temperature during forming the Ga-Sb thin film is preferably less than 500°C and more preferably less than 350°C and even more preferably below 200°C. If an amorphous thin film is desired the temperature can be lowered even further down to at or below about 90°C. In some embodiments the deposition temperature can be below about 80°C, below about 70°C, or even below about 60°C. [0312] The skilled artisan can determine the optimal reactant evaporation temperatures based on the properties of the selected precursors.
• the Ga and Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds.
• the pulse and purge times can vary much more and longer pulse times may be used even in order of minutes.
• the deposited Ga-Sb thin films are amorphous. In some embodiments, the deposited Ga-Sb thin films are crystalline.
• the deposited Ga-Sb film can be annealed.
• a thin film comprising Co and Sb is formed by
• a thin film comprising Co and Sb is formed on a substrate by an ALD type process comprising multiple deposition cycles, each deposition cycle comprising:
• Co-Sb deposition cycle This can be referred to as the Co-Sb deposition cycle.
• Each Co-Sb deposition cycle typically forms at most about one monolayer of Co-Sb.
• the Co-Sb deposition cycle is repeated until a film of a desired thickness is formed. In some embodiments a Co-Sb film of from about 10 A to about 2000 A is formed.
• the x and y values and composition of the Co x Sb y film can vary. In some embodiments, x and y are less than 1. In some embodiments, the sum of x and y is equal to about 1, or 100 if the x and y values are expressed as a percentage.
• the illustrated Co-Sb deposition cycle begins with provision of the Co precursor
• the deposition cycle begins with the provision of the Sb precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Sb or Co precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the Co source is Co-amidinate or Co-betadiketonate, such as Co(acac) 2 , Co(acac) 3> Co(thd) 2 or Co(thd) 3 .
• the Sb precursor can be any of the Sb precursors described herein.
• the second Sb precursor has a formula of Sb(SiR 1 R 2 R 3 ) 3 , wherein R 1 , R 2 , and R are alkyl groups comprising one or more carbon atoms.
• R , R , and R alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• Further materials or dopants that can be included in the Co-Sb deposition cycles include transition metals such as Fe, La or Ce.
• the substrate temperature during forming the Co-Sb thin film is preferably less than 500°C and more preferably less than 350°C and even more preferably below 200°C. If an amorphous thin film is desired the temperature can be lowered even further down to at or below about 90°C. In some embodiments the deposition temperature can be below about 80°C, below about 70°C, or even below about 60°C.
• the skilled artisan can determine the optimal reactant pulse times through routine experimentation based on the properties of the selected precursors and the desired properties of the deposited Co-Sb thin film.
• the Co and Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds. In some cases like in batch ALD reactors the pulse and purge times can vary much more and longer pulse times may be used even in order of minutes.
• the deposited Co-Sb thin films are amorphous. In some embodiments, the deposited Co-Sb thin films are crystalline.
• the deposited Co-Sb film can be annealed.
• ZnSb has also been studied for its potential use as a thermoelectric material.
• a thin film comprising Zn-Sb is formed by ALD without the use of plasma.
• An Zn-Sb thin film is formed on a substrate by an ALD type process comprising multiple Zn-Sb deposition cycles, each deposition cycle comprising:
• a first vapor phase reactant pulse comprising a Zn precursor into the reaction chamber to form no more than about a single molecular layer of the Zn precursor on the substrate;
• Each Zn-Sb deposition cycle typically forms at most about one monolayer of Zn-Sb.
• the Zn-Sb deposition cycle is repeated until a film of a desired thickness is formed. In some embodiments a Zn-Sb film of from about 10 A to about 2000 A is formed.
• the x and y values and composition of the Zn x Sb y film can vary. In some embodiments, x and y are less than 1. In some embodiments, the sum of x and y is equal to about 1, or 100 if the x and y values are expressed as a percentage. [0334] Although the illustrated Zn-Sb deposition cycle begins with provision of the Zn precursor, in other embodiments the deposition cycle begins with the provision of the Sb precursor.
• the reactants and reaction by-products can be removed from the reaction chamber by stopping the flow of Zn or Sb precursor while continuing the flow of an inert carrier gas such as nitrogen or argon.
• the Zn source is ZnX 2 , wherein X is a halogen element.
• the Zn source is ZnCl 2 .
• Zn source is zinc alkyl compound, such as dimethylzinc or ditehylzinc.
• the Sb precursor can be any of the Sb precursors described herein.
• the second Sb precursor has a formula of Sb(SiR R R ) 3 , wherein R , R , and R are alkyl groups comprising one or more carbon atoms.
• R , R , and R alkyl groups can be selected based on the desired physical properties of the precursor such as volatility, vapor pressure, toxicity, etc.
• the substrate temperature during forming the Zn-Sb thin film is preferably less than 500°C and more preferably less than 350°C and even more preferably below 200°C. If an amorphous thin film is desired the temperature can be lowered even further down to at or below about 90°C. In some embodiments the deposition temperature can be below about 80°C, below about 70°C, or even below about 60°C.
• the Zn and Sb reactants are pulsed for about 0.05 to 10 seconds, more preferably about 0.2 to 4 seconds.
• the purge steps in which excess reactant and reaction by-products, if any, are removed are preferably about 0.05 to 10 seconds, more preferably about 0.2-4 seconds.
• the pulse and purge times can vary much more and longer pulse times may be used even in order of minutes.
• the deposited Zn-Sb thin films are amorphous. In some embodiments, the deposited Zn-Sb thin films are crystalline.
• the deposited Zn-Sb film can be annealed.
• precursors comprising As, Bi, or P can be substituted for any of the Sb precursors described herein.
• the As precursor is AsiSilV ⁇ Bu ⁇ , As(SiEt 3 ) 3 , or As(SiMe 3 ) 3 .
• the Bi precursor is Bi(SiMe2 l Bu)3, Bi(SiEt 3 ) 3 , or Bi(SiMe 3 ) 3 .
• the P precursor is PCSiMe ⁇ Bub, P(SiEt 3 ) 3 , or P(SiMe 3 ) 3 .
• thin films comprising As can be made including: As-Te, As-Se, In-As, Ga-As, In-Ga-As, As-S and Al-As. Any of the precursors and compounds described herein can be used with the As precursors. In some preferred embodiments the As precursor is As ⁇ iMe ⁇ Bub, As(SiEt 3 ) 3 , or As(SiMe 3 ) 3 .
• thin films comprising Bi can be made including: elemental Bi, Bi-Te, Bi-Se, In-Bi, Sb-Bi, Ga-Bi, and Al-Bi. Any of the precursors and compounds described herein can be used with the Bi precursors.
• the Bi precursor is Bi(SiMe 2 t Bu) 3 , Bi(SiEt 3 ) 3 , or Bi(SiMe 3 ) 3 .
• thin films comprising P can be made including: P-Te, P-Se, In-P, Ga-P, Cu-P and Al-P. Any of the precursors and compounds described herein can be used with the P precursors.
• the P precursor is PCSiMe ⁇ Bu ⁇ , P(SiEt 3 ) 3 , or P(SiMe 3 ) 3 .
• a Ga-As film is deposited using GaCl 3 and As(SiH 3 ) 3 as precursors.
• a film comprising a Group III-V compound semiconductor film is deposited having a formula of (M , M , M )(A , A , A ) i.e. M 1 x M 2 yM 3 2 A 1 pA 2 k A 3 i s where M's can be selected from Al, Ga or In and A's can be selected from P, As, Sb.
• the Group III-V compound semiconductor film is a ternary compound, such as (Ga, Al)As, Ga(As,Sb) or (Ga, In) As film.
• the Group III-V compound semiconductor film is a quaternary compound film, such as a (Ga, In)(As, P) film or a (Al, In, Ga)P film.
• Ga-As films were deposited using GaCl 3 and As(SiEt 3 ) 3 as precursors. 500 cycles of Ga-As were used to deposit Ga-As on a silicon substrate with native oxide. Reaction temperatures were 100 °C and 120 °C. The As(SiEt 3 ) 3 source temperature was from about 50 °C to about 70 °C. The GaCl 3 was held at room temperature. Each Ga-As cycle was:
• the Ga-As films were characterized by EDX analysis as Gao .58 As 0.42 .
• the growth rate for the Gao. 58 As 0 . 4 2 films were approximately from about 0.5 A/cycle to about 0.7 A/cycle.
• EDX analysis also found that some chlorine and oxygen was present in the deposited Ga-As films. It is to be noted that these processes are not optimized and therefore some impurities in the films are not uncommon.
• precursors comprising N can be substituted for the Sb precursors described herein and used in the ALD cycles.
• the precursor comprising N is N(SiMe 2 l Bu) 3 , N(SiH 3 ) 3 , N(SiEt 3 ) 3 , or N(SiMe 3 ) 3 .
• the precursor comprising N is N(SiMe 3 )H.
• the precursor comprising N described herein is not N(SiH 3 ) 3 .
• the precursors comprising N can be used in an ALD cycle with a precursor comprising B, Al, Ga, or In to deposit a thin film including: B-N, Al-N, Ga-N and In-N.
• a film comprising a Group III-V compound semiconductor film is deposited having a formula of (M 1 , M 2 , M 3 )N i.e. M 1 x M 2 y M 3 z N, where M's can be selected from Al, Ga or In.
• the Group III-V compound semiconductor film comprises a ternary compound, such as (Ga,In)N, Ga(N,P), (Ga,Al)N or (Al, In)N film.
• the Group III-V compound semiconductor film comprises a quaternary compound, such as (Ga,In)(N,P), (Ga, In)(As, N), (Al, In)(N, P) or (Al, In, Ga)N.
• a quaternary compound such as (Ga,In)(N,P), (Ga, In)(As, N), (Al, In)(N, P) or (Al, In, Ga)N.
• Controlling the composition of materials with three or more elements (ternary or higher) can be difficult. However, it is easier to control the composition of binary materials deposited by ALD.
• multiple ALD cycles can be used to deposit a first film followed by multiple ALD cycles to form a second film having a composition different from the first film. In some embodiments, two or more cycles are used to deposit the first film. In some embodiments, two or more cycles are used to deposit the second film.
• the stoichiometry of the resulting film can be precisely controlled by varying the ratio of the second cycles.
• the thickness of each deposited layer can be controlled by selecting the number ALD cycles.
• multiple ALD cycles can be used to deposit about a nanometer or more of the first or second film. In some embodiments, preferably about 1 to 6 nm of material is deposited.
• first and second films are formed.
• the first and second cycles can be alternated to form alternating thin films of the first and second films.
• three or more films with different compositions can be used to form a film having a desired composition, crystal structure, and other physical properties.
• the first and second films can be any of the materials described herein.
• the deposited film can comprise one or more of: Sb, Sb-Te, GeTe, Ge-Sb-Te, Sb 2 Te 3 , Sb 2 Te, Ge-Sb, Ge 2 Sb 2 Se 5 , Bi-Te, Bi-Se, Zn-Te, ZnSe,CuInSe 2 , and Cu(In,Ga)Se 2 .
• one or more dopants selected from the group consisting of O, N, C, Si, Sn, Ag, Al, Ga, P, Fe, Ge, In, Ag, Se, Te or Bi, but not limited to those, is introduced into film.
• the thin film can comprise a dielectric material.
• the dielectric material can comprise Si0 2 , Ti0 2 , A1 2 0 3 , Zr0 2 , and Hf0 2 .
• a dielectric material can be formed in combination with the phase change materials disclosed herein.
• Si0 2 can be deposited with Ge-Sb-Te thin films. The use of a dielectric layer with a phase change material can modify the crystallization temperatures, resistivity, stability and other characteristics of the deposited film.
• nanolaminates materials for example, CVD, RTCVD, etc.
• Sb-Te and Ge-Te cycles are used to deposit alternating layers of Sb 2 Te 3 and Ge-Te.
• the stoichiometry of the resulting film can be precisely controlled by varying the ratio of the Sb-Te and Ge-Te cycles.
• the thickness of each deposited layer can be controlled by selecting the number of Sb-Te and Ge-Te cycles.
• Sb, Sb-Te, and Ge-Te cycles are used to deposit alternating layers of Sb, St3 ⁇ 4Te 3 , and Ge-Te.
• Sb-Se and Ge-Se cycles are used to deposit alternating layers of Sl3 ⁇ 4Se 3 and Ge-Se.
• Sb, Sb-Se, and Ge-Se cycles are used to deposit alternating layers of Sb, St ⁇ Ses, and Ge-Se.
• the thin film is crystalline as deposited. In some embodiments, the thin film is amorphous as deposited.
• the thin film can be annealed in the presence of an inert gas, such as nitrogen. In some embodiments, annealing can modify the crystal structure of the deposited thin film.
• the nanolaminate thin films can have superior properties to bulk films. For example, a nanolaminate with 2-6 nm thick individual layers can exhibit lower programming currents and faster working times than a bulk GST film with the same total thickness.
• the group VA element is As, Sb, Bi, or P.
• precursors are synthesized having a formula of LCSiR 1 -* 2 -* 3 ⁇ , wherein L is As, Sb, Bi, or P and R 1 , R 2 , and R 3 are preferably alkyl groups with one or more carbon atoms.
• the Group VA precursor that is synthesized has a formula of L(SiMe 3 ) 3 and in other embodiments has a formula of L(SiEt 3 ) 3 with L being As, Sb, Bi, or P.
• Sb precursors having a formula of Sb(SiR R R ) 3 , wherein R 1 , R 2 , and R 3 are preferably alkyl groups with one or more carbon atoms can be synthesized.
• the Sb precursor that is synthesized is Sb(SiMe 3 ) 3 and in other embodiments is Sb(SiEt 3 ) 3 .
• FIG. 10 is a flowchart generally illustrating methods for forming Sb precursors.
• the process for making a Sb precursor comprises:
• R , R and R are alkyl groups with one or more carbon atoms
• X is a halogen atom, thereby forming Sb(SiR R R ) 3 .
• a Group IA elemental metal such as Li, Na, K, etc. is combined with elemental Sb.
• the Group IA element is provided as a powder or flakes and the elemental Sb is provided as a metal powder.
• a solvent preferably a hydrocarbon, either aromatic or non-aromatic compound, which has a suitable boiling point, such as tetrahydrofuran (THF, (CH 2 ) 4 0), or dimethoxyethane (DME, CH 3 OCH 2 CH 2 OCH 3 ) is added to the Group IA metal and Sb.
• THF tetrahydrofuran
• DME dimethoxyethane
• naphthalene C 10 H 8
• ammonia can be used to catalyze the reaction instead of naphthalene.
• the solvent is toluene or xylene.
• the solvent is s ether, with suitable boiling point.
• the mixture is heated and a reflux condenser is used to reflux the solution under an inert gas, such as argon, until completion of the reaction.
• a pressure vessel heated to a desired temperature can also be used instead of a reflux condenser. After a desired intermediate product is formed, the solution can be cooled down.
• a silicon containing compound is then added to
• the silicon containing compound has a formula of R R R SiX, wherein R , R , and R are preferably alkyl groups with one or more carbon atoms and X
• R , R , and R can be chosen based on the desired precursor properties of the final product, including vapor pressure, melting point, etc. In some
• R , R , and R can all be the same group. In other embodiments, R , R , and R ,
• R , R , and R can all be different groups.
• R , R , and R are all ethyl groups (Et).
• R , R , and R are all methyl groups (Me). In other words,
• R and R are methyl groups and R is a tertbutyl group (Me 2 Bu).
• X is CI.
• the silicon containing compound has a formula of Et 3 SiCl or Me 3 SiCl.
• the mixture is continuously stirred until the reaction is complete. In some embodiments the mixture is refluxed or heated under inert gas until completion of the reaction. After the reaction is substantially complete, the final product is separated and isolated from any solvents, by-products, excess reactants, or any other compounds that are not desired in the final product.
• the product can be a solid or liquid at standard temperature and pressure.
• (R 3 Si) 3 Sb compounds can be produced by reacting R 3 SiH with SbR 3 compounds.
• (SiR 3 ) 3 Sb compounds can be produced by reacting R 3 SiLi with SbCl 3 compounds.
• Sb(SiMe 3 ) 3 was produced by the following process. First, 2.02 g of sodium and was added to 200 ml of dry THF. 3.56 g of Sb powder and 0.1 g (5.47 mmol) of naphthalene were added to the sodium and THF mixture in a 350 ml Schlenk bottle. The resultant mixture was stirred and refluxed for 48 hours. The mixture was then cooled to room temperature.
• the recovered product weighed about 2.5 g resulting in a calculated reaction efficiency of about 25%.
• the composition of the product was verified to be Sb(SiMe 3 ) 3 by nuclear magnetic resonance (NMR) and mass spectroscopy (MS).
• the Sb(SiMe 3 ) 2 produced had a boiling point of about 88°C at a pressure of 2 Torr.
• Sb(SiEt 3 ) 3 was produced by a process similar to that described in Example 7. First, 0.45 g of lithium was added to 300 ml of dry THF along with 2.60 g of Sb powder and 0.1 g of naphthalene in a 350 ml Schlenk bottle. The resultant mixture was stirred and refluxed for 48 hours. The mixture was then cooled to room temperature.
• Sb(SiEt 3 ) 3 was produced by a process similar to that described in Example 7. First 4.2 g of sodium was added to 200 ml of dry DME (dimethoxyethane, CH 3 OCH 2 CH 2 OCH 3 ) along with 7.4 g of Sb powder and 0.4 g naphthalene in 600 ml Schlenk bottle. The resultant mixture was stirred and refluxed for approximately 70 hours. The mixture was then cooled to room temperature.
• the recovered product weighed about 21.3 g giving a yield of 77.5%.
• the composition of the product was verified to be Sb(SiEt 3 ) 3 by nuclear magnetic resonance (NMR) and mass spectroscopy (MS).
• the Sb(SiEt 3 ) 3 produced had a boiling point of about 150 °C at a pressure of 1 torr.
• As(SiEt 3 ) 3 was produced by a process similar to that described in Example 7. First 0.86 g of sodium was added to 150 ml of dry DME (dimethoxyethane, CH 3 OCH 2 CH 2 OCH 3 ) along with 0.89 g of As powder and 0.1 g naphthalene in 350 ml Schlenk bottle. The resultant mixture was stirred and refluxed for approximately 24 hours. The mixture was then cooled to -10 °C.
• the recovered product weighed about 2.8 g giving a yield of 56%.
• the composition of the product was verified to be As(SiEt 3 ) 3 by nuclear magnetic resonance (NMR) and mass spectroscopy (MS).
• Bi(SiEt 3 ) 3 was produced by a process similar to that described in Example 7. First 0.76 g of sodium was added to 100 ml of dry DME (dimethoxyethane, CH 3 OCH 2 CH 2 OCH 3 ) along with 2.31 g of Bi powder and 0.1 g naphthalene in 350 ml Schlenk bottle. The resultant mixture was stirred and refluxed for approximately 24 hours plus 4 days at room temperature. The mixture was then cooled to -10 °C.
• the recovered product weighed about 3.2 g giving a yield of 52%.
• the composition of the product was verified to be Bi(SiEt 3 ) 3 by nuclear magnetic resonance (NMR) and mass spectroscopy (MS).
• Precursors comprising As, Bi and P, such as (R 3 Si) 3 As, (R 3 Si) 3 P, and (R 3 Si) 3 Bi can also be synthesized using similar methods to those described here for Sb.

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