Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02107—Forming insulating materials on a substrate
  • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
  • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
  • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
  • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
  • H01L21/0228—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • 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
  • C23C16/22—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 deposition of inorganic material, other than metallic material
  • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
  • C23C16/40—Oxides
  • C23C16/401—Oxides containing silicon
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • 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
  • C23C16/22—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 deposition of inorganic material, other than metallic material
  • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
  • C23C16/40—Oxides
  • C23C16/405—Oxides of refractory metals or yttrium
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • 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]
  • C23C16/45527—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations
  • C23C16/45531—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations specially adapted for making ternary or higher compositions
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • 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]
  • C23C16/45527—Atomic layer deposition [ALD] characterized by the ALD cycle, e.g. different flows or temperatures during half-reactions, unusual pulsing sequence, use of precursor mixtures or auxiliary reactants or activations
  • C23C16/45536—Use of plasma, radiation or electromagnetic fields
  • C23C16/45542—Plasma being used non-continuously during the ALD reactions
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02107—Forming insulating materials on a substrate
  • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
  • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
  • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
  • H01L21/02142—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing silicon and at least one metal element, e.g. metal silicate based insulators or metal silicon oxynitrides
  • H01L21/02159—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing silicon and at least one metal element, e.g. metal silicate based insulators or metal silicon oxynitrides the material containing zirconium, e.g. ZrSiOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
  • H01L21/28008—Making conductor-insulator-semiconductor electrodes
  • H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
  • H01L21/28158—Making the insulator
  • H01L21/28167—Making the insulator on single crystalline silicon, e.g. using a liquid, i.e. chemical oxidation
  • H01L21/28194—Making the insulator on single crystalline silicon, e.g. using a liquid, i.e. chemical oxidation by deposition, e.g. evaporation, ALD, CVD, sputtering, laser deposition
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02107—Forming insulating materials on a substrate
  • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
  • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
  • H01L21/02123—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon
  • H01L21/02142—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing silicon and at least one metal element, e.g. metal silicate based insulators or metal silicon oxynitrides
  • H01L21/02148—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material containing silicon the material containing silicon and at least one metal element, e.g. metal silicate based insulators or metal silicon oxynitrides the material containing hafnium, e.g. HfSiOx or HfSiON
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/02104—Forming layers
  • H01L21/02107—Forming insulating materials on a substrate
  • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
  • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
  • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
  • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
  • H01L21/02274—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]

Definitions

• the present invention relates to metal silicate films.
• the invention concerns methods for forming metal silicate films by atomic layer deposition (ALD).
• ALD atomic layer deposition
• High-k dielectric materials should preferably be able to be deposited on silicon surfaces and remain stable under thermal annealing processes.
• electrically active defects should be minimized or prevented from forming at interfaces between silicon wafers and high-k dielectrics.
• Hafnium silicate (HfSiO x ) and Zirconium silicate (ZrSiO x ) have been used to replace silicon oxide in some applications, such as complementary metal oxide semiconductor (CMOS) applications, because they can offer excellent thermal stability and device performance in integrated circuits with device features sizes of about 65 nanometers (nm) or less.
• CMOS complementary metal oxide semiconductor
• hafnium silicate films with compositional and thickness uniformities suited for current and future generation of ICs have become increasingly difficult to deposit hafnium silicate films with compositional and thickness uniformities suited for current and future generation of ICs.
• halide-based source chemicals e.g., MX 4 and SiY 4 , wherein "M” is a metal and "X” and “Y” are halides
• MX 4 and SiY 4 wherein "M” is a metal and "X” and “Y” are halides
• purely organic source chemicals lead to carbon impurities in the film, which behave as charge centers. At high concentrations, carbon impurities promote leakage currents that lead to increased power consumption in CMOS devices and decreased storage capabilities in DRAM devices.
• ALD methods for forming a metal silicate film comprise alternately contacting a substrate in a reaction space with vapor phase pulses of an alkyl amide metal compound, a silicon halide compound and an oxidizing agent.
• ALD processes for forming a metal silicate film comprise (a) contacting a substrate in a reaction space with a vapor phase pulse of an alkyl amide metal compound; (b) removing excess alkyl amide metal compound and reaction by-products from the reaction space; (c) contacting the substrate with a vapor phase pulse of a first oxidizing agent; (d) removing excess first oxidizing agent and reaction by-products from the reaction space; (e) contacting the substrate with a vapor phase pulse of a silicon halide compound; (f) removing excess silicon halide compound and reaction by-products from the reaction space; (g) contacting the substrate with a vapor phase pulse of a second oxidizing agent; (h) removing excess second oxidizing agent and reaction by-products from the reaction space; and (i) repeating steps (a) through (h) until a hafnium silicate film of desired thickness is formed over the substrate.
• ALD methods are provided for forming a metal silicate film for use in a dynamic random access memory (DRAM) device.
• the methods comprise alternately and sequentially providing into a reaction space vapor phase pulses of an alkyl amide metal compound and an oxidizing agent to deposit metal oxide over a substrate in the reaction space.
• the methods further comprise alternately and sequentially providing into the reaction space vapor phase pulses of a silicon halide compound and an oxidizing agent to deposit silicon oxide over the substrate.
• ALD methods for forming a metal silicate film for use as a gate dielectric in a complementary metal oxide semiconductor (CMOS) device comprise providing into a reaction space a vapor phase pulse of an alkyl amide metal compound to deposit at most a monolayer of a metal- containing film on a substrate in the reaction space.
• a vapor phase pulse of an oxidizing agent is provided into the reaction space to oxidize the deposited metal to metal oxide, thereby forming a metal-oxide containing film.
• a vapor phase pulse of a silicon halide compound is provided into the reaction space to deposit silicon on the substrate.
• a vapor phase pulse of an oxidizing agent is provided into the reaction space to oxidize the deposited silicon to silicon oxide, thereby forming the metal silicate film.
• hafnium silicate films are provided.
• the hafnium silicate films preferably comprise carbon impurity concentrations of less than or equal to about 50,000 parts-per-million (ppm) and halogen impurity concentrations of less than or equal to about 20,000 ppm.
• the hafnium silicate films have step coverages greater than or equal to about 85%.
• Figure 1 is a block diagram of a pulsing sequence according to a preferred embodiment of the invention.
• Metal silicate films formed using alkyl amide metal source chemicals i.e., metal source chemicals comprising alkyl amide ligands
• halide- based silicon source chemicals can advantageously permit formation of high quality metal silicate films at substantially lower temperatures, thereby enabling improved step coverage relative to films formed using prior art methods.
• alkyl amide metal source chemicals due to the lower barrier of activation, permit higher growth rates at lower temperatures relative to films formed using only halide-based source chemicals, thus enabling substantial savings in processing costs.
• Films formed according to preferred methods have carbon and halogen impurity levels that offer improved scalability and fixed charge characteristics for various applications, such as gate stacks in CMOS devices, dielectric layers in DRAM devices and components of other capacitor-based devices.
• an ALD process generally refers to a process for producing thin films over a substrate molecular layer by molecular layer using self- saturating chemical reactions.
• the general principles of ALD are disclosed, e.g., in U.S. Pat. Nos. 4,058,430 and 5,711,811, and Suntola, e.g., in the Handbook of Crystal Growth 3, Thin Films and Epitaxy, Part B: Growth Mechanisms and Dynamics, Chapter 14, Atomic Layer Epitaxy, pp. 601-663, Elsevier Science B.V. 1994, the entire disclosures of which are incorporated herein by reference.
• gaseous reactants are conducted separately (usually alternately and sequentially) into a reaction space of an ALD type reactor where they contact a substrate located in the space to provide a surface reaction.
• the pressure and the temperature of the reaction space are adjusted to a range where physisorption (i.e., condensation of gases) and thermal decomposition of the precursors are avoided, hi addition, reactants that do not react with themselves are selected. Consequently, only up to one monolayer (i.e., an atomic layer or a molecular layer) of material is deposited at a time during each pulsing cycle.
• the actual growth rate of the thin film which is typically presented as A/pulsing cycle, depends, for example, on the number of available reactive surface sites and the bulkiness of the reactant molecules. That is, once all available binding sites are filled, no additional surface reactions are possible. Gas phase reactions between precursors and any undesired reaction by-products are inhibited because reactant pulses are separated from each other by time and/or space.
• the reaction space is typically purged with an inert gas (e.g., N 2 , Ar, He, or H 2 ) and/or evacuated, e.g., using a vacuum pump, between reactant pulses to remove excess gaseous reactants and reaction by-products, if any.
• an inert gas e.g., N 2 , Ar, He, or H 2
• reaction space is used to designate a reactor or reaction chamber, or an arbitrarily defined volume therein, in which conditions can be adjusted to effect film growth over a substrate by ALD.
• the reaction space typically includes surfaces subject to all reaction gas pulses from which gases or particles can flow to the substrate, by entrained flow or diffusion, during normal operation.
• the reaction space can be, for example, the reaction chamber in a single-wafer ALD reactor or the reaction chamber of a batch ALD reactor, where deposition on multiple substrates takes place at the same time.
• the reactor can be configured for plasma generation, either in situ or remote.
• Plasma-excited species refers to radicals, ions or other excited species generated via application (or coupling) of energy to a reactant gas. Energy may be applied via a variety of methods, such as, e.g., induction, ultraviolet radiation, microwaves and capacitive coupling.
• the plasma generator may be a direct plasma generator (i.e., in situ or direct plasma generation) or a remote plasma generator (i.e., ex situ or remote plasma generation). In the absence of coupling energy, plasma generation is terminated.
• Plasma-excited species include, without limitation, hydrogen radicals.
• plasma-excited species of a particular vapor phase chemical e.g., O 2
• plasma-excited species are formed external to the reaction space comprising the substrate.
• “Adsorption” is used to designate a chemical attachment of atoms or molecules on a surface.
• “Substrate” is used to designate any workpiece on which deposition is desired. Typical substrates include, without limitation, silicon, silica, coated silicon, copper metal and nitride.
• “Surface” is used to designate a boundary between the reaction space and a feature of the substrate.
• Metal silicate film designates a film that comprises silicon, one or more metals and oxygen.
• a metal silicate film can be generally denoted by M x Si y O z , wherein "M” designates one or more metals and "x", "y” and “z” are numbers greater than zero.
• a metal silicate film can be formed by depositing tiered and alternating layers of silicon oxide (e.g., SiO, SiO 2 ) and a metal oxide.
• a hafnium silicate film may be formed from alternating layers of HfO 2 and SiO 2 .
• a hafnium silicate film can be formed by depositing three layers of hafnium oxide separated by a layer of silicon oxide.
• the metal silicate film has a uniform composition throughout at the microscopic scale.
• the methods presented herein allow controlled deposition of a conformal metal silicate film on a substrate surface.
• Geometrically challenging applications such as deposition in high aspect-ratio features (e.g., vias and trenches), are possible due to the self-limiting nature of the surface reactions using preferred chemistries provided herein.
• ALD process is used to form metal silicate films over a substrate, such as an integrated circuit (IC) workpiece.
• the substrate or workpiece is placed in a reaction space and subjected to alternately repeated surface reactions of a silicon source chemical, a metal source chemical and an oxidizing agent.
• Preferred ALD methods include plasma-enhanced ALD (PEALD) processes, in which plasma-excited species are used as oxidizing agents, and "thermal" ALD processes, in which the substrate is heated during deposition.
• PEALD plasma-enhanced ALD
• each ALD cycle comprises at least four deposition steps or phases and utilizes at least three different reactants.
• first, second, and third reactants these designations do not imply that the reactants have to be introduced in this order.
• an ALD cycle may start with the second reactant or the third reactant.
• a fourth reactant may be employed, for example, if two different oxidizing species are to be used (as discussed in more detail below).
• first, second, third and fourth phases they are not necessarily carried out in this sequence.
• deposition may start with the third phase. Additional phases may be included, depending on, e.g., the desired film composition.
• the first reactant (also referred to as a "metal reactant” herein) is a metal source chemical and will chemisorb no more than about one monolayer of a metal (or a plurality of metals if a source chemical comprising a plurality of metals is used, or if a plurality of metal source chemicals are used) on the substrate surface.
• the metal reactant preferably comprises a transition metal ("metal") species desired in the metal silicate film being deposited.
• the metal reactant is a vapor phase species comprising one or both of zirconium (Zr) and hafnium (Hf).
• the metal reactant is preferably a compound comprising alkyl and/or amide groups, more preferably an alkyl amide metal compound.
• Preferred alkyl amide metal compounds include etrakis(ethylmethylamino)metal (TEMA-m, wherein "m” is the metal), tetrakis(diethylamino)metal (TDEA-m) and tetrakis(dimethylamino)metal (TDMA-m).
• the metal reactant is preferably an alkyl amide Hf source chemical, more preferably a source chemical selected from the group consisting of tetrakis(ethylmethylamino)hafnium (TEMAH), tetrakis(diethylamino)hafhium (TDEAH) and tetrakis(dimethylamino)hafnium (TDMAH).
• TEMAH tetrakis(ethylmethylamino)hafnium
• TDEAH tetrakis(diethylamino)hafhium
• TDMAH tetrakis(dimethylamino)hafnium
• the metal reactant is preferably an alkyl amide zirconium compound, more preferably a source chemical selected from the group consisting of tetrakis(ethylmethylamino)zirconium (TEMAZ), tetrakis(diethylamino)zirconium (TDEAZ) and tetrakis(dimethylamino)zirconium (TDMAZ).
• TEMAZ tetrakis(ethylmethylamino)zirconium
• TDEAZ tetrakis(diethylamino)zirconium
• TDMAZ tetrakis(dimethylamino)zirconium
• the second reactant (also referred to as "oxidizing agent” or “oxidizing species” herein) comprises an oxidizing agent.
• the oxidizing agent is capable of oxidizing silicon and metals on the substrate surface.
• the oxidizing agent is a vapor phase species selected from the group consisting of water, ozone and plasma-excited species of molecular oxygen (O 2 ).
• the oxidizing agent comprises oxygen ions and/or radicals (i.e., plasma-excited species of oxygen).
• plasma-excited species of oxygen may be generated in the reaction space comprising the substrate using, e.g., a showerhead-type PEALD reactor, such as the reactor disclosed in U.S. Patent Application No. 10/486,311 , the disclosure of which is incorporated herein by reference in its entirety.
• plasma-excited species of oxygen are generated externally (i.e., remote plasma generation) and directed into the reaction space comprising the substrate.
• the oxidizing agent preferably reacts with silicon and/or metal on the substrate surface to form silicon oxide and/or metal oxide.
• Plasma parameters include, without limitation, radio frequency (“RF") power on time, RF power amplitude, RF power frequency, reactant concentration, reactant flow rate, reaction space pressure, total gas flow rate, reactant pulse durations and separations, and RF electrode-to-substrate spacing.
• RF radio frequency
• the spacing between a showerhead and the substrate surface may be selected to direct plasma-excited species of oxygen predominantly to the substrate surface, hi this manner, exposure of plasma-excited species of oxygen at other locations of the reaction space (e.g., reaction space walls not in view of the plasma) may be minimized, if not eliminated.
• the third reactant (also referred to as "silicon reactant” herein) is preferably a vapor phase silicon source chemical (also referred to as “silicon source material” or “silicon halide source chemical” herein) and will chemically adsorb ("chemisorb") on the substrate surface in a self-limiting manner to form no more than about one monolayer of silicon.
• the silicon source chemical is a silicon halide compound, such as, e.g., Si x W y H 2 , wherein "W” is a halide selected from the group consisting of F, Cl, Br and I, "x" and “y” are integers greater than zero, and "z” is an integer greater than or equal to zero.
• the silicon halide compound preferably forms a molecular monolayer (also "monolayer” herein) terminated with halogen ligands on the substrate.
• a silicon halide source chemical may be selected from the group consisting of silicon fluorides (e.g., SiF 4 ), silicon chlorides (e.g., SiCl 4 ), silicon bromides (e.g., SiBr 4 ), and silicon iodides (e.g., SiI 4 ).
• the silicon halide compound is silicon tetrachloride (SiCl 4 ).
• a fourth reactant may be used.
• the fourth reactant is preferably an oxidizing agent, more preferably an oxidizing agent selected from the group consisting of water, ozone and plasma-excited species of molecular oxygen (O 2 ).
• one or more additional reactants may be provided.
• an additional metal reactant may be utilized if more than one metal is to be incorporated in the silicate.
• the substrate may be provided with an initial surface termination.
• a silicon substrate may be contacted with water to form OH surface terminations on one or more surfaces of the substrate.
• a pulse of the metal reactant i.e., metal source chemical
• the amount of metal source chemical that can adsorb on the surface is determined at least in part by the number of available binding sites on the surface and by the physical size of the chemisorbed species (including ligands).
• the metal source chemical which is preferably an alkyl amide source chemical (e.g., TEMAH, TEMAZ), can be provided with the aid of a carrier gas (e.g., N 2 , He, Ar).
• Excess metal source chemical and reaction by-products are removed from the reaction space, for example with the aid of a purge gas (e.g., N 2 , He, Ar) and/or a vacuum generated by a pumping system. If the metal source chemical is supplied with the aid of a carrier gas, excess metal source chemical and reaction by-products may be removed by terminating the flow of the metal source chemical and continuing to supply the carrier gas.
• the carrier gas serves as the purge gas.
• a pulse of the oxidizing agent is provided into the reaction space.
• the oxidizing agent may be introduced with the aid of a carrier gas (e.g., N 2 , He, Ar).
• the oxidizing agent reacts with the metal-containing film left on the substrate surface by the preceding pulse.
• the oxidizing agent preferably oxidizes metal in the previously deposited film to metal oxide (MO x , wherein "M” is a metal).
• MO x metal oxide
• the oxidizing agent preferably oxidizes hafnium to hafnium oxide HfO x (e.g., HfO, HfO 2 ).
• Excess oxidizing agent and reaction by-products are removed from the reaction space.
• This step may include purging the reaction space with an inert gas (e.g., N 2 , He, Ar) and/or pumping the reaction space with the aid of a pumping system after terminating the pulse of the oxidizing agent.
• an inert gas e.g., N 2 , He, Ar
• the removal step may include terminating power to the plasma generator and purging excess oxidizing agent and reaction by-products, if any, e.g., with the aid of an inert gas.
• molecular oxygen may serve as the purge gas, such that when plasma power is terminated, oxygen is directed through the reaction space to purge reaction by-products, if any. If the oxidizing agent is supplied with the aid of a carrier gas, excess oxidizing agent and reaction by-products, if any, may be removed by terminating the flow of the oxidizing agent and continuing to supply the carrier gas.
• a metal oxide film is formed on the substrate.
• the first phase and the second phase (performed in sequence) can be collectively referred to as the "metal oxide phase”.
• the silicon reactant i.e., silicon source chemical
• the silicon source chemical which is preferably a halogen-containing silicon source chemical (e.g., SiCl 4 )
• SiCl 4 can be provided with the aid of an inert carrier gas.
• Maximum step coverage on the workpiece surface is obtained when no more than about a one monolayer of the silicon source chemical is chemisorbed in each self-limiting pulse. Due to the size of the chemisorbed species and the number of reactive sites, less than a monolayer (ML) is typically deposited in each pulse of the silicon source chemical.
• Excess silicon reactant and reaction by-products are removed from the reaction space.
• This step may include terminating the pulse of the silicon reactant and purging the reaction space with an inert gas (e.g., N 2 , He, Ar) and/or pumping the reaction space with the aid of a pumping system. If the silicon reactant is supplied with the aid of a carrier gas, excess silicon reactant and reaction by-products, if any, maybe removed by terminating the flow of the silicon reactant and continuing to supply the carrier gas.
• an inert gas e.g., N 2 , He, Ar
• a pulse of an oxidizing agent is provided into the reaction space.
• the oxidizing agent may be to the same as the oxidizing agent used in the second phase. However, the skilled artisan will understand that in some cases a different oxidizing agent (i.e., fourth reactant) than that used in the second phase may be used.
• the oxidizing agent reacts with the silicon left on the substrate surface by the preceding pulse to form a silicon oxide (SiO x ). It will be appreciated that SiO x may comprise SiO (partial oxidation) and SiO 2 (complete oxidation). In preferred embodiments, the oxidizing agent completely oxidizes silicon to SiO 2 .
• a silicon oxide film is deposited (or formed) on the substrate.
• the third and fourth phases (performed in sequence) can be collectively referred to as the "silicon oxide phase.”
• a pulsing sequence may include the following sequence of pulses: silicon reactant pulse/ oxidizing agent pulse/ metal reactant pulse/ oxidizing agent pulse, m other embodiments, the reactant pulses may initiate with an oxidizing agent pulse.
• the reactant pulses may include the following sequence of pulses: oxidizing agent pulse/ metal reactant pulse/ oxidizing agent pulse/ silicon reactant pulse/ oxidizing agent pulse.
• formation of the metal silicate film may proceed according to the following sequence of pulses: metal reactant pulse/ silicon reactant pulse/ oxidizing agent pulse.
• the silicon reactant pulse may precede the metal reactant pulse such that the pulsing sequence is silicon reactant pulse/ metal reactant pulse/ oxidizing agent pulse.
• the reactant pulses are preferably separated by a removal step, in which excess reactants and/or reaction byproducts (if any) are removed from the reaction space, preferably with the aid of a purge gas and/or a pumping system, as described above.
• each of the phases may be repeated a predetermined number of times prior to the other phases.
• the metal oxide phase can be repeated five times prior to the silicon oxide phase.
• the silicon oxide phase can be repeated eight times prior to the metal oxide phase. This can allow control of the stoichiometry of the metal silicate film being formed. If a metal-rich metal silicate film is desired, the metal oxide phase may be repeated several times prior to the silicon oxide phase. On the other hand, if a silicon-rich metal silicate film is desired, the silicon oxide phase can be repeated several times prior to the metal oxide phase. A film with more than one type of metal can be formed by adding additional metal phases.
• a phase is generally considered to immediately follow another phase if only a purge or other reactant removal step intervenes.
• an ALD cycle comprises:
• formation of the metal silicate film proceeds via formation of a metal oxide film followed by formation of a silicon oxide film.
• the sequence of steps (steps 1-8) described above may be repeated to form a metal silicate film of desired thickness.
• the ALD sequence described above begins with the vapor phase pulse of the silicon source chemical (step 5), which is sequentially followed by steps 6, 7, 8, 1, 2, 3 and 4.
• steps 6, 7, 8, 1, 2, 3 and 4. formation of the metal silicate film may proceed via formation of a silicon oxide film followed by formation of a metal oxide film.
• the substrate may be heated during one or more of the processing steps above.
• the substrate may be heated during steps 1 and 5 to provide activation energy for reaction between the silicon surface or a previously- deposited film and the metal or silicon reactant.
• the substrate may be heated during steps 1-8.
• providing an oxidizing agent includes introducing molecular oxygen (O 2 ) into the reaction space comprising the substrate and generating plasma-excited species of oxygen in situ (i.e., in the reaction space). Power is provided to an RF electrode to generate the plasma. After a desired exposure time, plasma production is terminated and excess O 2 and reaction by-products (if any) are removed from the reaction space using a purge and/or evacuation step (steps 4 and 8).
• plasma-excited species of oxygen are generated in a chamber in fluid communication with the reaction space comprising the substrate, and subsequently directed into the reaction space.
• steps 1-8 can be repeated a desired number of times prior to subsequent steps, hi some cases, this can provide a desired level of metal and/or silicon coverage on the substrate surface.
• steps 1-4 the metal oxide phase
• steps 5-8 the silicon oxide phase
• steps 5-8 can be repeated ten times, more preferably about 7 or 8 times, prior to steps 1-4.
• the substrate temperature and/or reaction space pressure can be selected to optimize growth of the metal silicate film. Films are formed at a substrate temperature preferably between about 15O 0 C and 500 0 C, more preferably between about 25O 0 C and 35O 0 C.
• the pressure of the reaction space during formation of the metal silicate film is preferably between about 0.1 and 100 Torr, more preferably between about 0.5 and 10 Torr.
• FIG. 1 An exemplary pulsing sequence according to methods of preferred embodiments is illustrated in Figure 1.
• the metal silicate film being formed is hafnium silicate. It will be appreciated, however, that these methods can be applied to forming metal silicate films comprising other metals, such as zirconium, in which case the metal source chemical used can be selected as described above.
• a metal reactant or source material is supplied 102 into the reaction space comprising the substrate, hi the illustrated embodiment, the metal reactant is TEMAH, which is supplied into the reaction space with the aid of a carrier gas (e.g., N 2 , He, or Ar).
• a carrier gas e.g., N 2 , He, or Ar.
• the metal reactant pulse 102 self-saturates the workpiece surfaces in such a way that any excess constituents of the metal reactant pulse do not further react with the monolayer formed by this process. Self-saturation is facilitated by ligands, terminating the monolayer, which protect the layer from further reaction with the reactant.
• Step 104 may entail stopping the flow of the metal reactant or chemistry while continuing to flow a carrier gas for a sufficient time to diffuse or purge excess reactants and reaction by-products from the reaction space.
• the purge gas is different from the carrier gas.
• the carrier gas serves as the purge gas during the reactant removal step 104.
• the reaction space is purged with greater than about two reaction space volumes of the purge gas, more preferably with greater than about three reaction space space volumes.
• the removal 104 comprises flowing purge gas for between about 0.1 seconds and 20 seconds after stopping the flow of the metal reactant pulse.
• step 104 may entail terminating the flow of the metal source chemical and introducing an inert gas into the reaction space.
• the reaction space may be pumped down between alternating chemistries. See, for example, PCT publication number WO 96/17107, published Jun. 6, 1996, entitled “Method and Apparatus for Growing Thin Films," the entire disclosure of which is incorporated herein by reference.
• the removal step 104 may entail simultaneously purging and pumping the reaction space. Together, the adsorption 102 and reactant removal 104 represent a first phase 120 of the illustrated ALD cycle.
• an oxidizing agent is pulsed 106 to the substrate.
• the oxidizing agent desirably reacts with or adsorbs upon the monolayer left by the metal reactant.
• the oxidizing agent is H 2 O, which oxidizes hafnium to hafnium oxide (HfO x ), such as, e.g., HfO and HfO 2 .
• the H 2 O pulse is terminated and excess water vapor and any reaction by-products are removed 108 from the reaction space, preferably with the aid of a purge gas pulse and/or a vacuum generated by a pumping system.
• the removal step 108 may be as described for step 104 above.
• steps 106 and 108 represent a second phase 130 of the illustrated ALD process.
• a silicon reactant or source material is supplied 110 to the substrate.
• the silicon reactant pulse 110 comprises providing a volatile halogen-containing silicon source chemical. Accordingly, in step 110 a halogen-containing silicon film is formed on the hafnium oxide film formed in the first and second phases 120 and 130.
• the silicon reactant is silicon tetrachloride (SiCl 4 ) and the silicon reactant pulse 110 leaves no more than a monolayer of a silicon-containing film on the substrate.
• step 112 preferably comprises stopping the flow of the third chemistry (silicon reactant) and continuing to flow carrier gas for a time period sufficient to remove excess reactants and any reaction by-products from the reaction space.
• the silicon reactant pulse 110 and removal step 112 represent a third phase 140 of the illustrated ALD process.
• the oxidizing agent H 2 O
• Water desirably reacts with the monolayer left by the silicon reactant.
• Water oxidizes the silicon deposited in step 110 to silicon oxide, preferably a silicon oxide selected from the group consisting of SiO and SiO 2 , thereby forming a silicon oxide film on the substrate.
• Exposure of the film to water may be accompanied by the formation of HCl, which evolves into the gas phase.
• halogen atoms may remain in the film following step 114.
• water is used in illustrated step 114, the oxidizing agent used in step 114 may differ from that used in step 106.
• plasma-excited species of oxygen may be used in step 114.
• the pulse of the oxidizing agent (H 2 O) is terminated and excess water vapor and any reaction by-products are removed 116 from the reaction space, preferably with the aid of a purge gas pulse and/or a vacuum generated by a pumping system.
• the removal step 116 can be as described for step 104 above.
• steps 114 and 116 represent a fourth phase 150 of the illustrated ALD process.
• the first phase 120, second phase 130, third phase 140 and fourth phase 150 are repeated 160 until a hafnium silicate film of desired thickness is formed on the substrate.
• the four phases may be repeated 10 times, 100 times, 1000 times or more to form a compositionally uniform hafnium silicate film.
• the ALD sequence illustrated in Figure 1 begins with the third phase 140 and is sequentially followed by the fourth phase 150, the first phase 120 and the second phase 130.
• the sequence of steps includes: silicon source chemical pulse/ reactant removal/ oxidizing species pulse/ reactant removal/ metal source chemical pulse/ reactant removal/ oxidizing species pulse/ reactant removal. This sequence may be repeated until a hafnium silicate film of desired thickness is formed on the substrate.
• a hafnium silicate film may be formed by an ALD cycle comprising the following vapor phase pulsing sequence: SiCl 4 / inert gas/ H 2 O/ inert gas/ TEMAH/ inert gas/ H 2 O/ inert gas.
• the ALD sequence illustrated in Figure 1 begins with the first phase 120 and is sequentially followed by the third phase 140 and the fourth phase 150. hi such a case, the second phase is omitted. Accordingly, the sequence of steps includes: metal reactant pulse/ reactant removal/ silicon reactant pulse/ reactant removal/ oxidizing agent pulse/ reactant removal. This sequence may be repeated until a hafnium silicate film of desired thickness is formed on the substrate. As a particular example, a hafnium silicate film may be formed by an ALD cycle comprising the following vapor phase pulsing sequence: TEMAH/ inert gas/ SiCl 4 / inert gas/ H 2 O/ inert gas.
• Metal silicate films formed according to preferred methods preferably have thicknesses between about 0.5 and 40 nm, more preferably between about 1 and 15 nm. It will be understood that thicknesses can vary with application. For example, in gate dielectrics for CMOS devices, the metal silicate films preferably have thicknesses between about 1 and 5 nm. As another example, in DRAM devices, the metal silicate films preferably have thicknesses between about 3 and 15 nm. The skilled artisan will be able to select an appropriate thickness for a particular application.
• metal silicate films formed according to preferred methods have step coverages greater than or equal to about 80%, preferably greater than or equal to about 85%, and more preferably greater than or equal to about 95%, and most preferably about 100%, and dielectric constants preferably between about 4 and 50, more preferably between about 8 and 30.
• Metal silicate films formed according to methods described herein preferably have carbon impurity concentrations less than or equal to about 50,000 parts-per-million (ppm), preferably less than or equal to about 25,000 ppm, more preferably less than or equal to about 15,000 ppm and most preferably less than or equal to about 10,000 ppm.
• Halogen (e.g., chlorine) impurity concentrations are less than or equal to about 20,000 parts-per-million (ppm), preferably less than or equal to about 10,000 ppm, more preferably less than or equal to about 5,000 ppm and most preferably less than or equal to about 2,000 ppm.
• Metal silicate films formed according to methods described hererin preferably have "within wafer” (WIW) uniformities (1 sigma) of less than about 1% on surfaces comprising high aspect ratio trenches and vias.
• Leakage current densities are preferably less than or equal to about IxIO "3 A/cm 2 at an effective oxide thickness (EOT) of about 1.5 nm, more preferably less than or equal to about 1x10 "4 A/cm 2 at an EOT of about 1.5 nm, and most preferably less than or equal to about Ix 10 "5 A/cm2 at an EOT of about 1.5 nm.
• Metal silicate films formed according to methods described herein preferably have metal and silicon concentrations between about 40% metal/ 60% Si to about 90% metal/ 10% Si.
• metal silicate films comprising hafnium and zirconium (i.e., Hf x Zr y O x , wherein "x", "y” and “z” are numbers greater than zero).
• the metal silicate film may be formed by depositing alternating layers of hafnium oxide (HfOx) (or zirconium oxide (ZrO x ))/ silicon oxide/ zirconium oxide (or Hf oxide).
• a hafnium-zirconium silicate may be deposited from the following series of ALD cycles: hafnium oxide/ silicon oxide/ zirconium oxide/ silicon oxide/ hafnium oxide/ silicon oxide/ zirconium oxide.
• forming a hafnium-zirconium silicate may comprise depositing a hafnium-zirconium mixed oxide (HfZrO x ) layers and intervening silicon oxide layers, hi such a case, the hafnium-zirconium silicate may be deposited by ALD cycles: HfZrO x / SiO x / HfZrO x / SiO x .
• alkyl amide hafnium and zirconium source chemicals may be simultaneously or alternately pulsed into the reaction space.
• a source chemical comprising zirconium and hafnium may be used as the metal reactant in this case.
• a hafnium silicate film was deposited on a 300 mm silicon wafer using a PulsarTM reactor manufactured by ASM America, Inc.
• the wafer included trenches with depth-to-width aspect ratios greater than about 50:1.
• Deposition was conducted at a substrate temperature in the range of about 250 to 32O 0 C.
• the sequence processing steps included the following:
• Steps (l)-(8) were repeated until a hafnium silicate film with a thickness of about 34 A was formed on the silicon wafer. Uniform coverage was achieved within the trenches. A step coverage in excess of 95% was achieved. The film had a uniformity (1 sigma) of about 0.78%.
• a hafnium silicate film was grown on a 300 mm silicon wafer at a wafer temperature of about 300 0 C.
• TEMAH was used as the metal reactant
• S ⁇ C14 was used as the silicon reactant
• water was used as the oxidizing agent.
• the pulsing sequence was TEMAH/H 2 O/SiCl 4 /H 2 ⁇ .
• the reaction space was purged with Ar between each of said pulses.
• Each cycle included a TEMAH/H 2 O pulsing sequence followed by five SiCl 4 /H 2 O pulsing sequences ⁇ i.e., Hf/Si pulse ratio was 1:5).
• the growth rate of the hafnium silicate film was about 0.95 A / cycle.
• the hafnium silicate film formed had a hafnium concentration of about 18%, a silicon concentration of about 15% and an oxygen concentration of about 66%. Carbon and chlorine impurity levels were less than about 1% (i.e., 10,000 ppm) and 0.2% (i.e., 2000 ppm), respectively, as determined by nuclear reaction analysis (NEA) and rutherford backscattering spectrometry (RBS).
• the hafnium silicate film had a step coverage of about 100%.

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