Method for producing a metal-containing or metalloid-containing film

Abstract

The present invention belongs to the field of methods for preparing films containing inorganic metals or inorganic semi-metals. The method for preparing a film containing an inorganic metal or an inorganic semi-metal comprises: (a) depositing a metal-containing or semi-metal-containing compound from the gaseous state onto a solid substrate and (b) contacting the solid substrate having the deposited metal-containing or semi-metal-containing compound with a compound of general formula (I) or (II); wherein Z is NR2, PR2, OR, SR, CR2, SiR2, X is H, R' or NR'2, wherein at least one X is H, n is 1 or 2, and R and R' are alkyl, alkenyl, aryl or silyl.

Description

[0001] The present invention belongs to the field of methods for producing films containing inorganic metals or inorganic semi-metals on a substrate, in particular atomic layer deposition methods.

[0002] With the continuous development of miniaturization, for example, in the semiconductor industry, the demand for inorganic thin films on substrates has increased, and the quality requirements for such films have become more stringent. Thin films of metals or semi-metals are used for different purposes, such as barrier layers, conductive features, or capping layers. Several methods for producing films of metals or semi-metals are known. One of them is to deposit a film-forming compound from the gas phase onto a substrate. In order to convert metal or semi-metal atoms into the gas phase at a moderate temperature, volatile precursors must be provided, for example, by complexing the metal or semi-metal with suitable ligands. These precursors must be stable enough for evaporation, but on the other hand, they need to be reactive enough to react with the deposition surface.

[0003] EP 1 788 116 A1 discloses a method for depositing aluminum films from dialkylamidoaluminum dihydride precursors. However, films other than aluminum films cannot be obtained by this method.

[0004] In order to convert the deposited metal or semi-metal complex into a metal or semi-metal film, the deposited metal or semi-metal complex usually has to be exposed to a reducing agent. Usually, hydrogen gas is used to convert the deposited metal or semi-metal complex into a metal or semi-metal film. Although hydrogen gas can act as a reducing agent for some metals, it usually requires plasma activation. Plasma methods are limited by a lower aspect ratio and can cause damage to the substrate plasma. Therefore, it is desirable to use a reducing agent that does not require any plasma activation.

[0005] WO 2019 / 201 692 A1 discloses a method for depositing metal films using bicyclic aluminum hydride compounds as reducing agents. Although this reducing agent usually gives good results, for some demanding applications, higher vapor pressures, stabilities, and / or reduction potentials are required.

[0006] Therefore, the object of the present invention is to provide a method for producing a film containing an inorganic metal or an inorganic semi-metal with fewer impurities in the film. The method materials should be easy to handle; in particular, they should be evaporated with as little decomposition as possible. In addition, the method materials should not decompose on the deposition surface under the method conditions, but at the same time should be reactive enough to participate in surface reactions. All reaction by-products should be volatile to avoid film contamination. In addition, the method should be adjustable so that the metal or semi-metal atoms in the method materials can be volatilized or incorporated into the film. Moreover, the method should be versatile so that it can be used to produce a wide range of different metals (including positively charged metal or semi-metal films).

[0007] These objects are achieved by a method for producing a film containing an inorganic metal or an inorganic semi-metal, the method comprising:

[0008] (a) depositing a metal- or metalloid-containing compound from the gaseous state onto a solid substrate, and

[0009] (b) contacting the solid substrate having the deposited metal- or metalloid-containing compound with a compound of general formula (I) or (II):

[0010]

[0011] wherein Z is NR2, PR2, OR, SR, CR2, SiR2,

[0012] X is H, R’ or NR’2, with at least one X being H,

[0013] n is 1 or 2, and

[0014] R and R’ are alkyl, alkenyl, aryl or silyl.

[0015] The present invention further relates to the use of a compound of general formula (I) or (II) as a reducing agent in a chemical vapor deposition process.

[0016] Preferred embodiments of the present invention are visible in the description and claims. Combinations of different embodiments fall within the scope of the present invention.

[0017] The process according to the present invention is suitable for the preparation of inorganic metal- or inorganic metalloid-containing films. In the context of the present invention, inorganic refers to a material containing at least 5% by weight, preferably at least 10% by weight, more preferably at least 20% by weight, especially at least 30% by weight of at least one metal or metalloid. Inorganic films typically contain carbon only in the form of carbide phases, which include mixed carbide phases such as nitride carbide phases. The carbon content of the carbon that is not part of the carbide phase in the inorganic film is preferably less than 5% by weight, more preferably less than 1% by weight, especially less than 0.2% by weight. Preferred examples of inorganic metal- or inorganic metalloid-containing films are metal or metalloid nitride films, metal or metalloid carbide films, metal or metalloid carbonitride films, metal or metalloid alloy films, intermetallic compound films or films containing mixtures thereof.

[0018] The film prepared by the method according to the present invention contains a metal or a metalloid. It is possible for the film to contain one metal or metalloid or more than one metal and / or metalloid. Metals include Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Bi. Metalloids include B, Si, Ge, As, Sb, Se, Te. Preferably, the metal or metalloid has an oxide formation energy per oxygen atom that is more exothermic than that of Ni. In particular, the metal or metalloid is Ti, Ta, Mn, Mo, W, Ge, Ga, As, In, Sb, Te, Al or Si.

[0019] The solid substrate can be any solid material. These include, for example, metals, metalloids, oxides, nitrides, and polymers. The substrate can also be a mixture of different materials. Examples of metals are aluminum, steel, zinc, and copper. Examples of metalloids are silicon, germanium, and gallium arsenide. Examples of oxides are silicon dioxide, titanium dioxide, and zinc oxide. Examples of nitrides are silicon nitride, aluminum nitride, titanium nitride, and gallium nitride. Examples of polymers are polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyamide.

[0020] The solid substrate can have any shape. These include thin sheets, films, fibers, particles of various sizes, and substrates with grooves or other indentations. The solid substrate can have any size. If the solid substrate has a particulate shape, the particle size can range from below 100 nm to several centimeters, preferably from 1 μm to 1 mm. To avoid the particles or fibers adhering to each other when depositing a metal- or metalloid-containing compound on the particles or fibers, it is preferably kept in motion. This can be achieved, for example, by stirring, drum, or fluidized bed techniques.

[0021] The method according to the present invention comprises (a) depositing a metal- or metalloid-containing compound from the gaseous state onto a solid substrate. The metal- or metalloid-containing compound contains at least one metal or metalloid atom. Metals include Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Bi. Metalloids include B, Si, Ge, As, Sb, Se, Te. Preferably, the metal or metalloid has an oxide formation energy per oxygen atom that is more exothermic than Ni. In particular, the metal- or metalloid-containing compound contains Ti, Ta, Mn, Mo, W, Ge, Ga, As, In, Sb, Te, Al or Si. It is possible for more than one metal- or metalloid-containing compound to be deposited on the surface simultaneously or successively. If more than one metal- or metalloid-containing compound is deposited on the solid substrate, it is possible for the metal- or metalloid-containing compounds to contain the same metal or metalloid or different ones, preferably they contain different metals or metalloids.

[0022] Any metal- or metalloid-containing compound that can be made gaseous is suitable. These compounds include metal or metalloid alkyls such as dimethylzinc, trimethylaluminum; metal alkoxides such as tetramethoxysilane, tetraisopropoxyzirconium or tetraisopropoxytitanium; metal or metalloid cyclopentadienyl complexes such as pentamethylcyclopentadienyl-trimethoxytitanium or bis(ethylcyclopentadienyl)manganese; metal or metalloid carbenes such as tris(neopentyl)neopentyltantalum or bis(imidazolidinylidene)ruthenium chloride; metal or metalloid halides such as aluminum trichloride, tantalum pentachloride, titanium tetrachloride, molybdenum pentachloride, germanium tetrachloride, gallium trichloride, arsenic trichloride or tungsten hexachloride; carbon monoxide complexes such as chromium hexacarbonyl or nickel tetracarbonyl; amine complexes such as bis(tert-butylimino)bis(dimethylamido)molybdenum, bis(tert-butylimino)bis(dimethylamido)tungsten or tetrakis(dimethylamido)titanium; diketonate complexes such as tris(acetylacetonato)aluminum or bis(2,2,6,6-tetramethyl-3,5-heptanedionato)manganese. Metal or metalloid halides are preferred, especially aluminum chloride, aluminum bromide and aluminum iodide. Preferably, the metal- or metalloid-containing compound has a molecular weight of at most 1000 g / mol, more preferably at most 800 g / mol, especially at most 600 g / mol, for example at most 500 g / mol.

[0023] If in the process according to the invention the substrate temperature is kept below the decomposition temperature of the metal- or metalloid-containing compound, a single layer is generally deposited on the solid substrate. Once the molecules of the metal- or metalloid-containing compound are deposited on the solid substrate, further deposition on top of it generally becomes less favorable. Thus, the deposition of the metal- or metalloid-containing compound on the solid substrate preferably represents a self-limiting process step. The typical layer thickness of the self-limiting deposition process step is 0.01 - 1 nm, preferably 0.02 - 0.5 nm, more preferably 0.03 - 0.4 nm, especially 0.05 - 0.2 nm. The layer thickness is generally measured by ellipsometry as described in PAS 1022 DE (Referenzverfahren zur Bestimmung von optischen und dielektrischen Materialeigenschaften sowie der Schichtdicke dünner Schichten mittels Ellipsometrie; February 2004).

[0024] The process according to the invention comprises (b) bringing the solid substrate with the deposited metal- or metalloid-containing compound into contact with a compound of general formula (I) or (II). Z is NR2, PR2, OR, SR, CR2, SiR2, preferably NR2, PR2, OR, SR, especially NR2 or PR2. The Zs can be all the same or different from each other, preferably they are the same. X is H, R’ or NR’2, where at least one X is H, preferably at least one X for each Al atom is H, especially all Xs are H, or one X for each Al atom is H and the other Xs are NR’2 or R’. In the context of the present invention, H includes all isotopes of hydrogen, especially 1 H and 2 H. The latter is also referred to as deuterium D. Depending on Z, the index n can be 1 or 2. Generally, if Z is NR2, PR2, OR, SR, then n is 2, and if Z is CR2, SiR2, then n is 1.

[0025] R and R’ in the compound of general formula (I) or (II) are alkyl, alkenyl, aryl or silyl, preferably alkyl or silyl, especially methyl, ethyl, isopropyl, sec-butyl, tert-butyl, trimethylsilyl. R and R’ can be the same or different from each other, preferably, all Rs are the same, preferably all R’s are the same, especially all Rs and R’s are the same. Two Rs can together form a ring, preferably a 3 - 8 membered ring, especially a 5 or 6 membered ring.

[0026] The alkyl group can be straight-chain or branched. Examples of straight-chain alkyl groups are methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl. Examples of branched alkyl groups are isopropyl, isobutyl, sec-butyl, tert-butyl, 2-methylpentyl, neopentyl, 2-ethylhexyl, cyclopropyl, cyclohexyl, indanyl, norbornyl. Preferably, the alkyl group is a C1-C8 alkyl group, more preferably a C1-C6 alkyl group, especially a C1-C4 alkyl group, such as methyl, ethyl, isopropyl or tert-butyl.

[0027] The alkenyl group contains at least one carbon-carbon double bond. The double bond can include the carbon atom to which R or R' is bonded to the rest of the molecule, or it can be located further away from the carbon atom to which R or R' is bonded to the rest of the molecule. The alkenyl group can be straight-chain or branched. Examples of straight-chain alkenyl groups (where the double bond includes the carbon atom to which R or R' is bonded to the rest of the molecule) include 1-ethenyl, 1-propenyl, 1-n-butenyl, 1-n-pentenyl, 1-n-hexenyl, 1-n-heptenyl, 1-n-octenyl. Examples of straight-chain alkenyl groups (where the double bond is located further away from the carbon atom to which R or R' is bonded to the rest of the molecule) include 1-n-propene-3-yl, 2-buten-1-yl, 1-buten-3-yl, 1-buten-4-yl, 1-hexen-6-yl. Examples of branched alkenyl groups (where the double bond includes the carbon atom to which R or R' is bonded to the rest of the molecule) include 1-propene-2-yl, 1-n-butene-2-yl, 2-butene-2-yl, cyclopenten-1-yl, cyclohexen-1-yl. Examples of branched alkenyl groups (where the double bond is located further away from the carbon atom to which R or R' is bonded to the rest of the molecule) include 2-methyl-1-butene-4-yl, cyclopenten-3-yl, cyclohexen-3-yl. Examples of alkenyl groups having more than one double bond include 1,3-butadien-1-yl, 1,3-butadien-2-yl, cyclopentadien-5-yl.

[0028] Aryl includes aromatic hydrocarbons such as phenyl, naphthyl, anthryl, phenanthryl and heteroaromatic groups such as pyrrolyl, furyl, thienyl, pyridyl, quinolinyl, benzofuryl, benzothienyl, thienothiophenyl. Combinations of several of these groups or these groups are also possible, such as biphenyl, thienylphenyl or furylthienyl. The aryl group can be substituted, for example, by a halogen (such as fluorine, chlorine, bromine, iodine); by a pseudohalogen (such as cyanide, cyanate, thiocyanate); by an alcohol; by an alkyl chain or an alkoxy chain. Aromatic hydrocarbons are preferred, and phenyl is more preferred.

[0029] A silyl group is a silicon atom typically having three substituents. Preferably, the silyl group has the formula SiE3, where E is, independently of one another, hydrogen, alkyl, aryl or silyl. It is possible that all three Es are the same, or that two Es are the same and the remaining E is different, or that all three Es are different from one another, preferably all Es are the same. Alkyl and aryl are as described above. Examples of silyl groups include SiH3, methylsilyl, trimethylsilyl, triethylsilyl, tri-n-propylsilyl, triisopropylsilyl, tricyclohexylsilyl, dimethyltert-butylsilyl, dimethylcyclohexylsilyl, methyldiisopropylsilyl, triphenylsilyl, phenylsilyl, dimethylphenylsilyl, pentamethyldisilanyl.

[0030] Preferably, the compound of general formula (I) is one of the following general formulas.

[0031]

[0032]

[0033] Preferred examples of the compound of general formula (I) in terms of these general formulas are given in the table below.

[0034]

[0035]

[0036]

[0037]

[0038] Me represents methyl, Et represents ethyl, -(CH2)2- represents an ethylene group formed by two Rs, and -(CH2)4- represents a butylene group formed by two Rs.

[0039] The synthesis of some compounds of general formula (I) is described, for example, in E. Ashby et al., Inorganic Chemistry, Vol. 10 (1971), pp. 893 - 899 or I. Krossing et al., Zeitschrift für Naturforschung B, Vol. 63 (2008), pp. 1045 - 1051.

[0040] Preferably, the compound of general formula (II) is one of the following general formulas.

[0041]

[0042] Preferred examples of the compound of general formula (II) in terms of these general formulas are given in the table below.

[0043]

[0044]

[0045]

[0046]

[0047] Me represents methyl, Et represents ethyl, -(CH2)2- represents an ethylene group formed by two Rs, and -(CH2)4- represents a butylene group formed by two Rs.

[0048] The synthesis of some compounds of general formula (II) is described, for example, in K. Ouzounis et al., Zeitschrift fuer Anorganische und Allgemeine Chemie, Vol. 504 (1983), pp. 67 - 76 or A. Storr et al., Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry (1972 - 1999), 1972, pp. 326 - 330.

[0049] Preferably, R does not have a hydrogen atom at the 1 - position, i.e., R does not have a hydrogen atom bonded to an atom bonded to a nitrogen or oxygen atom, and thus is in the β - position relative to the aluminum atom. Also preferably, R' does not have a hydrogen atom at the 1 - position. More preferably, neither R nor R' has a hydrogen atom at the 1 - position. Examples are alkyl groups having two alkyl side chains at the 1 - position, i.e., 1,1 - dialkylalkyls, such as tert - butyl, 1,1 - dimethylpropyl; alkyl groups having two halogens at the 1 - position, such as trifluoromethyl, trichloromethyl, 1,1 - difluoroethyl; trialkylsilyls, such as trimethylsilyl, triethylsilyl, dimethyl - tert - butylsilyl; aryls, especially phenyl or alkyl - substituted phenyls, such as 2,6 - diisopropylphenyl, 2,4,6 - triisopropylphenyl. Alkyl groups that do not have a hydrogen atom at the 1 - position are particularly preferred.

[0050] The compounds of general formula (I) or (II) preferably have a molecular weight of not more than 1000 g / mol, more preferably not more than 800 g / mol, even more preferably not more than 600 g / mol, and especially not more than 500 g / mol.

[0051] Preferably, the compounds of general formula (I) or (II) have a melting point of - 80 to 125 °C, preferably - 60 to 80 °C, even more preferably - 40 to 50 °C, and especially - 20 to 20 °C. It is advantageous that the compounds of general formula (I) or (II) melt to obtain a clear liquid that remains unchanged before the decomposition temperature.

[0052] Preferably, the compound of general formula (I) or (II) has a decomposition temperature of at least 80 °C, more preferably at least 100 °C, especially at least 120 °C, for example at least 150 °C. Generally, the decomposition temperature is not greater than 250 °C. The compound of general formula (I) or (II) has a high vapor pressure. Preferably, the vapor pressure is at least 1 mbar at a temperature of 200 °C, more preferably 150 °C, especially 120 °C. Generally, the temperature at which the vapor pressure is 1 mbar is at least 50 °C.

[0053] The compound of general formula (I) or (II) used in the process according to the invention is used in high purity to obtain the best results. High purity means that the substance used contains at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight, especially at least 99% by weight of the metal-containing or metalloid-containing compound or the compound of general formula (I) or (II). The purity can be determined by elemental analysis according to DIN 51721 (Prüfung fester Brennstoffe - Bestimmung des Gehaltes an Kohlenstoff und Wasserstoff - Verfahren nach Radmacher - Hoverath, August 2001).

[0054] The compound of general formula (I) or (II) is brought into contact with the solid substrate in the gaseous state. For example, it can be made gaseous by heating it to a high temperature. In any case, a temperature below the decomposition temperature of the compound of general formula (I) or (II) must be selected. The decomposition temperature is the temperature at which the original compound of general formula (I) or (II) begins to change its chemical structure and composition. Preferably, the heating temperature is in the range of 0 °C to 300 °C, more preferably in the range of 10 °C to 250 °C, even more preferably in the range of 20 °C to 200 °C, especially in the range of 30 °C to 150 °C.

[0055] Another method of making the compound of general formula (I) or (II) gaseous is direct liquid injection (DLI) as described, for example, in US 2009 / 0 226612A1. In this method, the compound of general formula (I) or (II) is typically dissolved in a solvent and sprayed into a carrier gas or a vacuum. If the vapor pressure and temperature of the compound of general formula (I) or (II) are high enough and the pressure is low enough, the compound of general formula (I) or (II) is made gaseous. Various solvents can be used, provided that the compound of general formula (I) or (II) shows sufficient solubility in the solvent, for example at least 1 g / l, preferably at least 10 g / l, more preferably at least 100 g / l. Examples of these solvents are coordinating solvents such as tetrahydrofuran, dioxane, diethoxyethane, pyridine or non - coordinating solvents such as hexane, heptane, benzene, toluene or xylene. Solvent mixtures are also suitable.

[0056] Alternatively, the compound of general formula (I) or (II) can be made gaseous by direct liquid evaporation (DLE) as described, for example, by J. Yang et al. (Journal of Materials Chemistry, 2015). In this method, the compound of general formula (I) or (II) is mixed with a solvent (such as a hydrocarbon like tetradecane) and heated below the boiling point of the solvent. By evaporating the solvent, the compound of general formula (I) or (II) becomes gaseous. This method has the advantage of no particulate contaminants forming on the surface.

[0057] Preferably, the compound of general formula (I) or (II) is made gaseous under reduced pressure. In this way, the method can generally be carried out at a lower heating temperature, resulting in less decomposition of the compound of general formula (I) or (II). Pressurization can also be used to push the gaseous compound of general formula (I) or (II) towards the solid substrate. Generally, for this purpose, an inert gas (such as nitrogen or argon) is used as the carrier gas. Preferably, the pressure is from 10 bar to 10 -7 mbar, more preferably from 1 bar to 10 -3 mbar, especially 1 - 0.01 mbar, for example 0.1 mbar.

[0058] Exposure of the substrate having the compound of general formula (I) or (II) or the metal - or metalloid - containing compound may take from a few milliseconds to a few minutes, preferably from 0.1 second to 1 minute, especially 1 - 10 seconds. The longer the solid substrate is exposed to the compound of general formula (I) or (II) or the metal - or metalloid - containing compound at a temperature below the decomposition temperature of the compound of general formula (I) or (II) or the metal - or metalloid - containing compound, the more regular the film with fewer defects is formed.

[0059] Preferably, the compound of general formula (I) or (II) acts as a reducing agent in this method. In this case, before bringing it into contact with the compound of general formula (I) or (II), the metal - or metalloid - containing compound is deposited from the gas phase onto the solid substrate. Generally, the metal - or metalloid - containing compound is reduced to a metal, a metal nitride, a metal carbide, a metal carbonitride, a metal alloy, an intermetallic compound or a mixture thereof, where the metal or metalloid has a lower oxidation state after reduction. In the context of the present invention, a metal film is a metal - or metalloid - containing film having a high electrical conductivity, generally at least 10 4 S / m, preferably at least 10 5 S / m, especially at least 10 6 S / m.

[0060] Compounds of general formula (I) or (II) have a low tendency to form a permanent bond with the surface of a solid substrate having a deposited metal- or metalloid-containing compound. Thus, the metal- or metalloid-containing film has an impurity content from reaction by-products incorporated from the compounds of general formula (I) or (II). Preferably, the metal- or metalloid-containing film contains in total less than 5% by weight, more preferably less than 1% by weight, especially less than 0.5% by weight, for example less than 0.2% by weight nitrogen.

[0061] A particular advantage of the process according to the invention is that the compounds of general formula (I) or (II) are highly versatile, so that the process parameters can vary within a wide range. Thus, the process according to the invention includes both CVD processes and ALD processes.

[0062] Preferably, the sequence comprising (a) and (b) is carried out at least 2 times, more preferably at least 5 times, even more preferably at least 10 times, especially at least 50 times. Usually, the sequence comprising (a) and (b) is carried out not more than 1000 times.

[0063] Usually, each time the solid substrate is exposed to a gas-phase formed metal- or metalloid-containing compound or a compound of general formula (I) or (II), the substrate and the equipment surrounding it are preferably purged with an inert gas. Preferred examples of the inert gas are nitrogen and argon. The purging can be carried out for 1 second to 1 minute, preferably 5 - 30 seconds, more preferably 10 - 25 seconds, especially 15 - 20 seconds.

[0064] Preferably, the substrate temperature is 5 - 40 °C, for example 20 °C, higher than the temperature at which the metal- or metalloid-containing compound becomes gaseous. Preferably, the substrate temperature is from room temperature to 400 °C, more preferably 100 - 300 °C, for example 150 - 220 °C.

[0065] Preferably, after depositing the metal- or metalloid-containing compound on the solid substrate and before bringing the solid substrate having the deposited metal- or metalloid-containing compound into contact with the compound of general formula (I) or (II), the solid substrate having the deposited metal- or metalloid-containing compound is brought into contact with an acid in the gas phase. Without being bound by theory, it is believed that protonation of the ligands of the metal- or metalloid-containing compound facilitates its decomposition and reduction. Suitable acids include hydrochloric acid and carboxylic acids, preferably carboxylic acids, such as formic acid, acetic acid, propionic acid, butyric acid or trifluoroacetic acid, especially formic acid.

[0066] The method according to the present invention yields a film containing an inorganic metal or an inorganic semi-metal. The film can be just a single metal monolayer or can be thicker, for example, from 0.1 nm to 1 μm, preferably from 0.5 - 50 nm. The film can contain defects such as pores. However, these defects generally constitute less than half of the surface area covered by the film. The film preferably has a very uniform film thickness, which means that the variation in film thickness at different positions on the substrate is extremely small, usually less than 10%, preferably less than 5%. In addition, the film is preferably a conformal film on the substrate surface. Suitable methods for measuring film thickness and uniformity are XPS or ellipsometry.

[0067] The film obtained by the method according to the present invention can be used in electronic components. The electronic components can have structural features of various sizes, for example, from 1 nm to 100 μm, such as 10 nm, 14 nm, or 22 nm. The method of forming a film for an electronic component is particularly suitable for very fine structures. Therefore, electronic components with dimensions below 1 μm are preferred. Examples of electronic components are field effect transistors (FETs), charge trapping memory cells, solar cells, light emitting diodes, sensors, or capacitors. In optical devices such as light emitting diodes or photoreceptors, the film obtained by the method according to the present invention is used to increase the refractive index of the layer that reflects light.

[0068] A preferred electronic component is a transistor. Preferably, the film acts as a chemical barrier metal in the transistor. A chemical barrier metal is a material that reduces the diffusion of adjacent layers while maintaining electrical connectivity. Examples

[0069] Example 1

[0070] An atomic layer deposition method was carried out using GeBr4, which is a compound containing a semi-metal, and Compound IIa-1. These compounds were each contained in a stainless steel cylinder and connected to a cross-flow ALD reactor with a deposition area of 1 inch diameter and an Ar (5N) carrier gas flow of 5 sccm. The base pressure was about 50 Pa. GeBr4 was heated to 55 °C and Compound IIa-1 was heated to 75 °C. 100 ALD cycles were carried out, each cycle consisting of a sequence of 100 ms GeBr4 exposure, a first 7.9-second purge, 100 ms Compound IIa-1 exposure, and a second 7.9-second purge, and monitored by in-situ quartz crystal microbalance (QCM). At a reactor temperature of 160 - 200 °C, an average QCM frequency change of -1 Hz / cycle was observed, indicating a stable mass growth, and there was an ALD window with a growth rate independent of temperature. GeBr4 exposure led to an increase in mass, while the mass decreased upon subsequent exposure to Compound IIa-1, showing the specific reactivity of Compound IIa-1 with the surface generated by GeBr4 exposure, but no deposition of Compound IIa-1.

[0071] Example 2

[0072] The same equipment, compounds, and ALD cycles as in Example 1 were used. A blank silicon wafer substrate having a native oxide surface or a 100 nm thermal oxide surface was placed in the reactor and maintained at a temperature of 160 °C. 1000 ALD cycles as described in Example 1 were performed and the substrate was analyzed after removal from the reactor. A layer with a thickness of approximately 14 nm as determined by ellipsometry was deposited on the native oxide wafer substrate. According to AFM analysis, the root mean square roughness of the similar ALD layer deposited on the thermal oxide substrate was 2 nm

[0073] Example 3

[0074] The same equipment as in Example 1 was used. GeCl4 and Compound IIa-1, which is a compound containing a semimetal, were used. GeCl4 was contained in a stainless steel cylinder and maintained at 0 °C in the ALD process. 100 ALD cycles were performed, each cycle consisting of a sequence of 20 ms GeCl4 exposure, 7.98 s purge, 100 ms Compound IIa-1 exposure, and 7.9 s purge, and monitored by in-situ quartz crystal microbalance (QCM). At a reactor temperature of 140 °C, the average QCM frequency change was -0.4 Hz / cycle, indicating a stable mass increase. GeCl4 exposure led to a mass increase, while the mass decreased by subsequent exposure to Compound IIa-1, indicating a specific reactivity of Compound IIa-1 with the surface generated by GeCl4 exposure, but no deposition of Compound IIa-1

Claims

1. A method for preparing a film containing an inorganic metal or an inorganic semi-metal, comprising: (a) depositing a metal- or metalloid-containing compound from the gaseous state onto a solid substrate, and (b) contacting the solid substrate having the deposited metal- or metalloid-containing compound with a compound of general formula (II) as a reducing agent, wherein Z is NR2, PR2, OR or SR, X is H, R’ or NR’2, where at least one X is H, n is 1 or 2, and R and R’ are methyl, ethyl, isopropyl, sec-butyl, tert-butyl, trimethylsilyl.

2. The method according to claim 1, wherein at least one X of each Al atom is H.

3. The method according to claim 1, wherein the metal-containing or semi-metal-containing compound contains Ti, Ta, Mn, Mo, W, Ge, Ga, As, In, Sb, Te, Al or Si.

4. The method according to claim 2, wherein the metal-containing or semi-metal-containing compound contains Ti, Ta, Mn, Mo, W, Ge, Ga, As, In, Sb, Te, Al or Si.

5. The method according to claim 1, wherein the metal-containing or semi-metal-containing compound is a metal or semi-metal halide.

6. The method according to claim 2, wherein the metal-containing or semi-metal-containing compound is a metal or semi-metal halide.

7. The method according to claim 3, wherein the metal-containing or semi-metal-containing compound is a metal or semi-metal halide.

8. The method according to claim 4, wherein the metal-containing or semi-metal-containing compound is a metal or semi-metal halide.

9. The method according to any one of claims 1-8, wherein the sequence containing (a) and (b) is performed at least twice.

10. The method according to any one of claims 1-8, wherein the compound of general formula (II) has a molar mass not greater than 600 g / mol.

11. The method according to claim 9, wherein the compound of general formula (II) has a molar mass not greater than 600 g / mol.

12. The method according to any one of claims 1-8, wherein the compound of general formula (II) has a vapor pressure of at least 1 mbar at a temperature of 200 °C.

13. The method according to claim 9, wherein the compound of general formula (II) has a vapor pressure of at least 1 mbar at a temperature of 200 °C.

14. The method according to claim 10, wherein the compound of general formula (II) has a vapor pressure of at least 1 mbar at a temperature of 200 °C.

15. The method according to claim 11, wherein the compound of general formula (II) has a vapor pressure of at least 1 mbar at a temperature of 200 °C.

16. Use of a compound of general formula (II) according to any one of claims 1 - 2 and 10 - 15 as a reducing agent in a chemical vapor deposition process.

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