Metalorganic compounds for the deposition of high purity tin oxide and a dry etching and deposition reactor for tin oxide films.

Abstract

Certain compounds of formula I:Q are useful for depositing high purity tin oxide. x -Sn-(A 1 R 1 ' z ) 4-x or Formula II: Sn(NR 2 (CH2) n A 2 )2, and methods of using such compounds. Also disclosed are compositions of organometallic compounds useful for depositing high-purity tin oxide that, when combined, provide improved stability. Also disclosed are methods for dry etching tin oxide using specific etchant gases and / or methods for dry etching substrates using specific etchant gases with specific additives.

Description

[Technical field]

[0001] The present disclosure relates to organometallic compounds useful for the deposition of high purity tin oxide, dry etching methods for dry etching such high purity tin oxide films, and deposition reactors for use in tin oxide film deposition methods. More specifically, the present disclosure describes certain compounds useful in the deposition of high purity tin oxide, and compositions that provide better stability during storage of compounds useful in the deposition of high purity tin oxide. The present disclosure also describes methods for dry etching tin oxide with certain etchant gases, and / or methods for dry etching substrates using certain etchant gases with certain additives. [Background technology]

[0002] In the following "Background of the Invention" description, reference is made to certain structures and / or methods. However, the reference below should not be construed as an admission that these structures and / or methods constitute prior art. Applicants expressly reserve the right to demonstrate that such structures and / or methods do not qualify as prior art.

[0003] The semiconductor industry is increasingly utilizing tin oxide conformal films during the fabrication of electronic devices. Such films can be fabricated using chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0004] To obtain the desired film, the reactive compounds used during the deposition process must be thermally stable while exhibiting good reactivity. Such properties allow the compound to be delivered to the deposition chamber without decomposition, which would result in non-uniform or other defects in the deposited film. The good stability and reactivity profile exhibited by the compounds of the present invention also means that less material needs to be delivered to the growth chamber (less material is more economical), cycle times are shorter (because less material remains in the chamber at the end of the process and has to be pumped out), and thicker films can be deposited in less time, thus increasing throughput. Thermal stability also means that the material can be much easier to purify after synthesis and is easier to handle.

[0005] Although there have been several attempts to find compounds with desired thermal stability and good reactivity, there remains a need for compounds with improved thermal stability and / or reactivity that can meet the increasing requirements of the industry.

[0006] There is also a desire to ensure the stability of the reactive compounds during storage. Many reactive compounds used to form tin oxide films are known to disproportionate or polymerize. This can cause problems when the reactive compounds are stored for a period of time prior to use in a deposition process. There is therefore a need to reduce the effects of disproportionation and increase the storage stability of reactive gases used in deposition processes to form tin oxide films.

[0007] In an atomic layer deposition (ALD) system, reactive gases are introduced sequentially to achieve self-limiting growth of conformal thin films of the desired material. In both cases, the reactor is a chamber made of materials that do not react with the chemicals being used. The reactor must also be able to withstand high temperatures. The chamber includes reactor walls, a liner, a pedestal, a gas injection unit, and a temperature control unit. The reactor walls are typically made of aluminum, stainless steel, or quartz. Ceramics such as Al2O3, Y2O3, or other exotic ceramics, or special glasses such as quartz, are often used as liners between the reactor walls and the pedestal in the reactor chamber. To prevent overheating, a coolant such as water can be circulated through channels in the reactor walls. The substrate rests on a pedestal that is kept at a controlled temperature. The pedestal is made of materials that are resistant to the metal-organic compounds being used, sometimes graphite.

[0008] When thin film deposition is performed, a film is deposited not only on the desired surface, but also on all interior surfaces of the MOCVD or ALD reactor, including the pedestal, walls, and ceiling. The more frequently the reactor is used without cleaning, the thicker the deposits become. The deposits eventually begin to flake off, creating particles that can fall onto the substrate wafer, contaminating it and resulting in reduced yields. The reactant gases flowing through the reactor chamber may also be contaminated by deposits. To avoid this, the reactor must be cleaned periodically. Depending on the reactor configuration and materials used, effective cleaning may require complete dismantling and wet cleaning of reactor parts, which is time consuming and reduces the efficiency of the reactor. Furthermore, reactors are typically constructed from a wide range of materials, such as 316L and 304 stainless steel, silicon carbide, graphite, tungsten, aluminum, pyrolytic boron nitride, other ceramics, and / or ethylene propylene diene (EPDN) polymers. It can be difficult to remove deposits from all these types of surfaces without the use of various types of etchants or other cleaning agents. Thus, a simpler and more effective means for cleaning inside the reactor is desired.

[0009] Furthermore, thin film manufacturing processes often include an etching step after deposition, where at least some of the deposition on the chamber walls is the same material that is etched from the thin film.

[0010] ALD reactors for the fabrication of single wafers containing tin oxide (SnO2) present particular problems in etching and cleaning the reaction chamber. For example, such reactors may use highly corrosive Cl- or Br-based chemistries that cause degradation of the chamber materials, require high temperatures that induce material stress, corrode the underlying materials of the ALD chamber, and / or require chamber shields or inserts to protect the chamber walls. When cleaning ALD reactors for tin oxide, the use of H2, CH4, or other reducing chemistries requires longer etching times and there are byproducts that condense on the reactor surfaces before being evacuated. The use of CH4 can also result in solid tin oxide containing Me-Sn-O, which is known to be more toxic than Sn-O residues. The byproducts in the case of tin oxide are prone to low-temperature decomposition, requiring temperature control below -10 to -30 °C and complicating the tool configuration. Also, the reducing atmosphere can reduce metal oxides to metals, which then act as a passivation layer.

[0011] US20040014327A1 "Method for etching high dielectric constant materials and for cleaning deposition chambers for high dielectric constant materials" teaches that another etchant, COCl2, can be used to etch metal oxides. However, COCl2 is a highly toxic nerve agent. The use of malonyl chloride as an etchant should be possible as well, but malonyl chloride is very unstable and decomposes as a liquid at room temperature, making it difficult to obtain in a sufficiently high purity and difficult to transport and store for long periods of time. Thus, an etchant that solves the above problems is needed. Summary of the Invention [Problem to be solved by the invention]

[0012] The present disclosure provides compounds useful for the deposition of high purity tin oxide. [Means for solving the problem]

[0013] The organometallic compound has the following formula I: Q x -Sn-(A 1 R 1 ' z ) 4-x Formula I (In the formula, Q is OR 1 or Cp, Each R 1 The groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms; Each R 1 ' groups are independently selected from the group consisting of alkyl, acyl or aryl groups having 1 to 10 carbon atoms; x is an integer from 0 to 3; When x is 0, A is O, and when x is an integer from 1 to 3, A is N; If A is O, then z is 1, and if A is N, then z is 2. This includes compounds of the formula:

[0014] The deposition of tin oxide using such compounds is also disclosed. The use of the compounds of formula I in the methods disclosed herein enables chemical vapor deposition (CVD) and atomic layer deposition (ALD) of tin oxide.

[0015] In embodiments, Q is a cyclopentadienyl ligand, Cp. In some embodiments, x is 1 and the compound of formula I has the following formula: Cp-Sn-(NR 1 '2)3(In the formula, each R 1 ' groups are independently selected from the group consisting of alkyl, acyl, or aryl groups having 1 to 10 carbon atoms.

[0016] In embodiments, x is an integer from 1 to 3. In such embodiments, the compound of formula I has the following formula: (OR 1 ) x -Sn-(NR 1 '2) 4-x (In the formula, each R 1 ' groups are independently selected from the group consisting of alkyl, acyl, or aryl groups having 1 to 10 carbon atoms, and x is an integer from 1 to 3.

[0017] In other embodiments, each R 1 Group and each R 1 Each R' group is an independently selected alkyl group having 1 to 10 carbon atoms. 1 Group and each R 1 It is contemplated that the R′ groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In embodiments, each R 1 Group and each R 1 The R' groups are independently selected alkyl groups having 1 to 4 carbon atoms. 1 Group and each R 1 In an embodiment, each R′ group is independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl.1 Group and each R 1 The ' groups represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0018] In an embodiment, x is 4. In such an embodiment, the compound of formula I has the following formula: Sn(OR 1 )4(in the formula, each R 1 The groups are independently selected from the group consisting of alkyl, acyl, or aryl groups having 1 to 10 carbon atoms.

[0019] In other embodiments, each R 1 Each R' group is an independently selected alkyl group having 1 to 10 carbon atoms. 1 It is contemplated that the R′ groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In embodiments, each R 1 The R' groups are independently selected alkyl groups having 1 to 4 carbon atoms. 1 In an embodiment, each R′ group is independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. 1 The ' groups represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0020] In an embodiment, the organometallic compound is selected from the group consisting of (MeO)2Sn(NMe2)2, (MeO)2Sn(NEtMe)2, (MeO)3Sn(NMe2), (MeO)3Sn(NEtMe), Sn(OMe)4, CpSn(NMe2)3, and CpSn(NMeEt)3.

[0021] Other organometallic compounds are represented by the following formula II: Sn(NR 2 (CH2) n A 2 )2 type II (In the formula, Each A 2 is NR 2 ' or O, Each R 2 groups are independently selected from the group consisting of hydrogen and alkyl or aryl groups having 1 to 10 carbon atoms; Each R 2 ' groups are independently selected from the group consisting of hydrogen and alkyl, acyl or aryl groups having 1 to 10 carbon atoms; n is 2 or 3, In some cases, NR 2 (CH2) n NR 2 ' forms a ring structure, Optionally, at least one of (CH2) has one or more substitutions with an alkyl group having 1 to 10 carbon atoms. This includes compounds of the formula:

[0022] The deposition of tin oxide using such compounds is also disclosed. The use of compounds of formula II in the methods disclosed herein enables chemical vapor deposition (CVD) and atomic layer deposition (ALD) of tin oxide.

[0023] In the embodiment, A 2 is O, and formula II is formula IIa: Sn(NR 2 (CH2) n O)2(in the formula, each R 2 The groups are independently selected from alkyl or aryl groups having 1 to 10 carbon atoms, or selected from alkyl groups having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. 2 The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl.

[0024] In embodiments, each R 2 The groups are independently selected from alkyl groups having 1 to 10 carbon atoms. 2 It is contemplated that the groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In embodiments, each R 2The groups are independently selected alkyl groups having 1 to 4 carbon atoms. 2 The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. 2 The groups represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0025] In embodiments, each R 2 Each R' group is independently selected from hydrogen or an alkyl group having 1 to 10 carbon atoms. 2 It is contemplated that the R′ groups may be independently selected from hydrogen or an alkyl group having 1 to 6 carbon atoms. 2 The R′ groups are independently selected from hydrogen or an alkyl group having 1 to 4 carbon atoms. 2 In an embodiment, each R′ group is independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. 2 The ' groups represent hydrogen or different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0026] In embodiments, n is 2. In other embodiments, n is 3. In embodiments, at least one of (CH2) has one or more substitutions with an alkyl group having 1-10 carbon atoms, or 1-6 carbon atoms, or 1-4 carbon atoms. Alternatively, the one or more substitutions are with methyl or ethyl. In particular embodiments, only one of (CH2) has one or more substitutions with an alkyl group, such as methyl or ethyl. In more particular embodiments, one of (CH2) is substituted with two methyl groups.

[0027] In an embodiment, formula II is Formula IIb:

[0028] [ka]

[0029] (In the formula, Each R 2 groups are independently selected from the group consisting of hydrogen and alkyl or aryl groups having 1 to 10 carbon atoms; Each R 2 ' groups are independently selected from the group consisting of hydrogen and alkyl, acyl or aryl groups having 1 to 10 carbon atoms; Each R 2 '' group and each R 2 ' ' groups are independently selected alkyl groups having 1 to 10 carbon atoms. It is expressed as:

[0030] In an embodiment, each R of formula IIb 2 , R 2 ', R 2 '', or R 2 The "" groups are independently selected from hydrogen or alkyl groups having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. In certain embodiments of Formula IIb, each R 2 and R 2 ' is hydrogen, and each R 2 '' and R 2 The "" group is an independently selected alkyl group having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. In a more detailed embodiment of Formula IIb, each R 2 and R 2 ' is hydrogen, and each R 2 '' and R 2 The ''' groups are independently selected from ethyl or methyl.

[0031] A 2 NR 2 In some embodiments, NR(CH2) n NR 2 In certain embodiments of the cyclic structure, R 2 and R2 In an embodiment, Formula II is represented by Formula IIc:

[0032] [ka]

[0033] #1 Formula IIc: It is expressed as:

[0034] In an embodiment, each (NR 2 (CH2) n A 2 ) is selected from the group consisting of N,N'-dimethylethylenediamine (NMe(CH2)2NMe), piperazine (N2C4H8), N,N'-diethylethylenediamine (NEt(CH2)2NEt), N,N'-diisopropylethylenediamine (NiPr(CH2)2NiPr), N,N'-di-tert-butylethylenediamine (NtBu(CH2)2NtBu), N,N'-dimethyl-1,3-propanediamine (NMe(CH2)3NMe), 2,2-dimethyl-1,3-propanediamine (NH(CH2)(C(CH3))(CH2)NH), 2-(methylamino)ethanol (NMe(CH2)2O), and 2-(ethylamino)ethanol (NEt(CH2)2O).

[0035] The present disclosure provides compositions in which a second organometallic compound is combined with a first organometallic compound to reduce disproportionation of the first organometallic compound and increase storage stability.

[0036] The composition comprises: Formula III: R 3 2Sn(NR 3 '2) Type 2 III (In the formula, Each R 3 The groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms; Each R 3' groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms. a first organometallic compound represented by Formula IV: Sn(NR 4 2) Type 4 IV (In the formula, each R 4 The groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms. The second organometallic compound is represented by the formula:

[0037] In other embodiments, each R 3 , R 3 ', and R 4 Each R group is an independently selected alkyl group having 1 to 10 carbon atoms. 3 , R 3 ', and R 4 It is contemplated that the groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In embodiments, each R 3 , R 3 ', and R 4 The groups are independently selected alkyl groups having 1 to 4 carbon atoms. 3 , R 3 ', and R 4 The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. 3 , R 3 ', and R 4 The groups represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0038] In an embodiment, the second organometallic compound is selected from the group consisting of Sn(NMe2)4, Sn(NEt2)4, and Sn(NMeEt)4.

[0039] The present disclosure provides novel etching methods that solve the above-mentioned problems in conventional methods of etching and cleaning ALD reactors, particularly ALD reactors in tin oxide production.

[0040] One method for solving the above-mentioned problems is a method for removing tin oxide deposits from an interior surface of a reactor chamber or from a substrate within said reactor chamber, comprising: introducing an etchant gas into the reactor chamber, the etchant gas being represented by general formula A 3 O m X n (In the formula, A 3 is selected from the group consisting of C, N, and S; O is oxygen; each X is independently selected from the group consisting of halogens; and the subscript m and n is greater than zero), activating the etchant gas either before or after said introduction; allowing an etching reaction to proceed between the activated etchant gas and the tin oxide deposit; and exhausting the etchant gas along with the gaseous products of the etching reaction. The present invention includes a method comprising the steps of:

[0041] Another method for solving the above-mentioned problems is a method for removing deposits from an inner surface of a reactor chamber or from a substrate within said reactor chamber, comprising the steps of: introducing an etchant gas and an additive into the reactor chamber, the etchant gas being represented by general formula A 3 O m X n (In the formula, A 3 is selected from the group consisting of C, N, and S; O is oxygen; each X is independently selected from the group consisting of halogens; and the subscript m and n is greater than zero), and the additive is a compound of general formula C x H y O z (wherein the subscriptx and z is greater than zero), activating the etchant gas either before or after said introduction; allowing an etching reaction to proceed between the activated etchant gas and the deposit; and exhausting the etchant gas along with the gaseous products of the etching reaction. The present invention includes a method comprising the steps of:

[0042] In one embodiment according to any of the above methods, X represents a combination of two different halogens.

[0043] In one embodiment according to any of the above methods, generating the etchant gas occurs prior to said introducing into the chamber.

[0044] In one embodiment according to any of the above methods, blowing a carrier gas through a liquid chemical to volatilize the liquid chemical into the etchant occurs prior to the introduction of the etchant gas into the chamber.

[0045] In one embodiment according to any of the above methods, the etchant gas is generated by infusing a carrier gas through multiple liquid chemical components and then combining the resulting gases.

[0046] In one embodiment according to any of the above methods, the etchant gas is generated by mixing two or more chemical component gases.

[0047] In one embodiment according to any of the above methods, the etchant gas is activated by exposure to an activation mechanism in a gas activation chamber prior to introduction into the chamber, the gas activation mechanism being selected from the group consisting of heat, ultraviolet light, and plasma discharge.

[0048] In one embodiment according to any of the above methods, the etchant gas, after introduction into the chamber, is activated by exposure to a thermal activation mechanism, the thermal activation mechanism being selected from the group consisting of the overall temperature within the chamber and a localized heat source within the chamber.

[0049] In one embodiment according to any of the above methods, the etchant gas is selected from the group consisting of COCl2, COBr2, COI2, SOI2, SOCl2, SOBr2, SO2Cl2, SO2Br2, NOCl, NOBr, NOI, SOClBr, SOClF, and SOFBr. In a particular embodiment, thionyl chloride (SOCl2) is used.

[0050] In one embodiment according to any of the above methods, the additive is CO or CO2.

[0051] In one embodiment according to any of the above methods, a halogen-containing additive is added to the gaseous mixture including the etchant gas.

[0052] In one embodiment according to any of the above methods, the halogen-containing additive is an active halogen or a compound of the general formula R 5 X 1 (In the formula, R 5 is selected from the group consisting of H and Me; 1 is a halogen selected from the group consisting of F, Cl, Br, and I.

[0053] In one embodiment according to any of the above methods, the active halogen comprises Cl or Br.

[0054] In one embodiment according to any of the above methods, a diluent additive is added to the gaseous mixture including the etchant gas.

[0055] In one embodiment according to any of the above methods, the diluent additive comprises N, Ar, He, or Ne.

[0056] In one embodiment according to any of the above methods, the reactor chamber is heated to a temperature of at least 100°C, between 100°C and 900°C, or between 100°C and 400°C.

[0057] In one embodiment according to any of the above methods, the reactor chamber is provided with a pressure between 0.1 mBar and 1,500 mBar, preferably between 0.1 mBar and 1,000 mBar.

[0058] The above and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments, as illustrated in the accompanying drawings. As will be understood, the present invention can be modified in various respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

[0059] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0060] [Figure 1] 1 is a comparative graph of the vapor pressure of several compounds that can be used to form a tin oxide film. [Diagram 2] FIG. 1 is a graph of wt. % Me2Sn(NMe2)2 versus days at a storage temperature of 70° C. [Diagram 3] 1 is a photograph of a test piece obtained after testing according to Example 21. [Figure 4] 13 is a graph of etch rate (A / min) versus power (W) for runs according to Example 22. [Diagram 5] 13 is a graph of etch rate (A / min) versus power (W) for only the runs in which the temperature was 26° C. according to Example 22. [Figure 6] FIG. 1 shows the 1H NMR spectrum of Sn(NMeEt)4. [Figure 7]FIG. 1 shows the 1H NMR spectrum of Sn(OtBu)4. [Figure 8] FIG. 1H NMR spectra of Sn(NMeEt)4 before and after addition of MeOH. [Figure 9] 1 is a graph comparing the weight percent of Sn(NMeEt)4 with HNMeEt versus weeks at a storage temperature of 60° C. [Figure 10] FIG. 1H NMR spectra of Sn(NMeEt)4 samples at 60° C. at 0, 4, and 9 weeks. [Figure 11] 1 is a graph comparing the weight percent of Sn(NMeEt)4 with HNMeEt versus weeks at a storage temperature of 100° C. [Figure 12] FIG. 1H NMR spectra of Sn(NMeEt)4 samples at 100° C. at 0, 4, and 9 weeks. [Figure 13] FIG. 1H NMR spectra of Sn(NMeEt)4 samples at 125° C. at 0, 1, and 2 weeks. [Figure 14] FIG. 1 shows a schematic diagram of a multi-stage vacuum distillation apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] The following detailed description may be read in conjunction with the accompanying drawings, in which like numerals indicate like elements and in which:

[0062] Formula I below: Q x -Sn-(A 1 R 1 ' z ) 4-x Formula I (In the formula, Q is OR 1 or Cp, Each R 1 The groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms; Each R 1' groups are independently selected from the group consisting of alkyl, acyl or aryl groups having 1 to 10 carbon atoms; x is an integer from 1 to 4; If x is 0, then A 1 is O, and when x is an integer between 1 and 3, A 1 is N, A 1 If is O, z is 1 and A 1 If N, then z is 2. Organometallic compounds of the formula are disclosed.

[0063] In embodiments, Q is a cyclopentadienyl ligand, Cp. In some embodiments, x is 1 and the compound of formula I has the following formula: Cp-Sn-(NR 1 '2)3(In the formula, each R 1 ' groups are independently selected from the group consisting of alkyl, acyl, or aryl groups having 1 to 10 carbon atoms.

[0064] Compounds of formula I include compounds where x is an integer from 1 to 3. In such embodiments, compounds of formula I have the following formula: (OR 1 ) x -Sn-(NR 1 '2) 4-x (In the formula, each R 1 ' groups are independently selected from the group consisting of alkyl, acyl, or aryl groups having 1 to 10 carbon atoms, and x is an integer from 1 to 3.

[0065] Formula: (OR 1 ) x -Sn-(NR 1 '2) 4-x Compounds of formula I represented by the formula 1 Group and each R 1 Each R' group is an independently selected alkyl group having 1 to 10 carbon atoms. 1 Group and each R 1 It is contemplated that each R′ group may be an independently selected alkyl group having 1 to 6 carbon atoms. 1 Group and each R1 Each R' group is an independently selected alkyl group having 1 to 4 carbon atoms. More specifically, each R 1 Group and each R 1 The R' groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. Also, in some compounds, each R 1 Group and each R 1 The ' groups may represent different alkyl, acyl or aryl groups, especially different alkyl groups.

[0066] Compounds of formula I include compounds where x is 4. In such embodiments, compounds of formula I have the following formula: Sn(OR 1 )4(in the formula, each R 1 The groups are independently selected from the group consisting of alkyl, acyl, or aryl groups having 1 to 10 carbon atoms.

[0067] Formula: Sn(OR 1 The compound of formula I represented by formula 4 is 1 Each R is an independently selected alkyl group having from 1 to 10 carbon atoms. 1 It is contemplated that the groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In particular, each R 1 The R groups are independently selected alkyl groups having 1 to 4 carbon atoms. More specifically, each R 1 The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. Also, in some compounds, each R 1 The groups represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0068] Specific organometallic compounds of formula I include the following: (MeO)Sn(NMe), (MeO)Sn(NEtMe), (MeO)Sn(NMe), (MeO)Sn(NEtMe), Sn(OMe), CpSn(NMe), or CpSn(NMeEt).

[0069] Other organometallic compounds are represented by the following formula II: Sn(NR 2 (CH2) n A 2 )2 type II (In the formula, Each A 2 is NR 2 ' or O, Each R 2 groups are independently selected from the group consisting of hydrogen and alkyl or aryl groups having 1 to 10 carbon atoms; Each R 2 ' groups are independently selected from the group consisting of hydrogen and alkyl, acyl or aryl groups having 1 to 10 carbon atoms; n is 2 or 3, In some cases, NR 2 (CH2) n NR 2 ' forms a ring structure, Optionally, at least one of (CH2) has one or more substitutions with an alkyl group having 1 to 10 carbon atoms. This includes compounds of the formula:

[0070] The deposition of tin oxide using such compounds is also disclosed. The use of compounds of formula II in the methods disclosed herein enables chemical vapor deposition (CVD) and atomic layer deposition (ALD) of tin oxide.

[0071] In the embodiment, A 2 is O, and formula II is formula IIa: Sn(NR 2 (CH2) n O)2(in the formula, each R 2 The groups are independently selected from alkyl or aryl groups having 1 to 10 carbon atoms, or selected from alkyl groups having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. 2The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl.

[0072] In embodiments, each R 2 The groups are independently selected from alkyl groups having 1 to 10 carbon atoms. 2 It is contemplated that the groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In embodiments, each R 2 The groups are independently selected alkyl groups having 1 to 4 carbon atoms. 2 The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. 2 The groups represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0073] In embodiments, each R 2 Each R' group is independently selected from hydrogen or an alkyl group having 1 to 10 carbon atoms. 2 It is contemplated that the R′ groups may be independently selected from hydrogen or an alkyl group having 1 to 6 carbon atoms. 2 The R′ groups are independently selected from hydrogen or an alkyl group having 1 to 4 carbon atoms. 2 In an embodiment, each R′ group is independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. 2 The ' groups represent hydrogen or different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0074] In embodiments, n is 2. In other embodiments, n is 3. In embodiments, at least one of (CH2) has one or more substitutions with an alkyl group having 1-10 carbon atoms, or 1-6 carbon atoms, or 1-4 carbon atoms. Alternatively, the one or more substitutions are with methyl or ethyl. In particular embodiments, only one of (CH2) has one or more substitutions with an alkyl group, such as methyl or ethyl. In more particular embodiments, one of (CH2) is substituted with two methyl groups.

[0075] In an embodiment, formula II is Formula IIb:

[0076] [ka]

[0077] (In the formula, Each R 2 groups are independently selected from the group consisting of hydrogen and alkyl or aryl groups having 1 to 10 carbon atoms; Each R 2 ' groups are independently selected from the group consisting of hydrogen and alkyl, acyl or aryl groups having 1 to 10 carbon atoms; Each R 2 '' group and each R 2 ' ' groups are independently selected alkyl groups having 1 to 10 carbon atoms. It is expressed as:

[0078] In an embodiment, each R of formula IIb 2 , R 2 ', R 2 '', or R 2 The "" groups are independently selected from hydrogen or alkyl groups having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. In certain embodiments of Formula IIb, each R 2 and R 2 ' is hydrogen, and each R 2 '' and R 2The "" group is an independently selected alkyl group having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. In a more detailed embodiment of Formula IIb, each R 2 and R 2 ' is hydrogen, and each R 2 '' and R 2 The ''' groups are independently selected from ethyl or methyl.

[0079] A 2 In some embodiments, where N is N, NR(CH2) n NR' forms a cyclic structure. In certain embodiments of the cyclic structure, the R and R' groups are alkyl groups selected from methyl or ethyl. In embodiments, Formula II is represented by Formula IIc: Formula IIc:

[0080] [ka]

[0081] It is expressed as: In an embodiment, each (NR 2 (CH2) n A 2 ) is selected from the group consisting of N,N'-dimethylethylenediamine (NMe(CH2)2NMe), piperazine (N2C4H8), N,N'-diethylethylenediamine (NEt(CH2)2NEt), N,N'-diisopropylethylenediamine (NiPr(CH2)2NiPr), N,N'-di-tert-butylethylenediamine (NtBu(CH2)2NtBu), N,N'-dimethyl-1,3-propanediamine (NMe(CH2)3NMe), 2,2-dimethyl-1,3-propanediamine (NH(CH2)(C(CH3))(CH2)NH), 2-(methylamino)ethanol (NMe(CH2)2O), and 2-(ethylamino)ethanol (NEt(CH2)2O).

[0082] The compounds of formula I and II, while exhibiting good reactivity, are thermally stable, which should allow delivery of the compounds to the deposition chamber without decomposition, which would result in non-uniform or defective deposited films. The good stability and reactivity profile exhibited by the compounds of the present invention also means that less material is expected to need to be delivered to the growth chamber (less material is more economical), cycle times are expected to be shorter (because less material remains in the chamber at the end of the process and has to be pumped out), and thicker films can be deposited in less time, thus increasing throughput. Furthermore, it is expected that ALD can be performed at much lower temperatures (or using a wider temperature range) using compounds of formula I or II. Thermal stability also means that the materials can be much easier to purify after synthesis and are easier to handle.

[0083] The compounds of formula I and II have an additional advantage over conventional compounds in that they are free of C-Sn bonds, which result in the formation of Me-Sn-O solid residues that are known to be more toxic than residues formed from compounds of formula I and II. Also, the compounds of formula I and II have a lower molecular weight than conventional compounds, yet are expected to have higher thermal stability than those conventional compounds.

[0084] Compounds of formula I or II can be prepared by methods known in the art. The following examples are illustrative of such methods but are not intended to be limiting. EXAMPLES

[0085] Example 1: Synthesis of Sn(NMeEt) Under an inert atmosphere, a 1 L round bottom flask was loaded with 67 mL of 2.5 M nBuLi solution in hexane and about 500 mL of anhydrous hexane. The contents of the flask were cooled in an ice / water bath, then 16 mL of HNMeEt was added dropwise to the reaction flask with vigorous stirring. The reaction mixture was stirred at room temperature for 1 h and then cooled again in an ice / water bath. 44.90 mL of SnCl was added dropwise to the reaction flask with a dropper. The reaction flask was covered with aluminum foil and its contents were left stirring at room temperature overnight. The next day, the LiCl salt was separated from the reaction mixture by filtration. 48.42 g (57% yield) of Sn(NMeEt) was isolated by distillation at 70° C. and 0.05 Torr. As shown in FIG. 6, 1 The product was confirmed to be Sn(NMeEt)4 by 1 H NMR spectroscopy. EXAMPLES

[0086] Example 2: Synthesis of Sn(OtBu) Under an inert atmosphere, a 1 L round bottom flask was charged with 10 g of SnCl4 and approximately 400 mL of anhydrous hexane. The contents of the flask were cooled in an ice / water bath, followed by slow addition of 16.6 mL of HNEt2 in 100 mL of anhydrous hexane to the reaction flask. The reaction mixture was then stirred at room temperature for 2 hours and then cooled again in an ice / water bath. A solution of 15.4 mL of tBuOH in approximately 50 mL of anhydrous hexane was then added to the flask and the reaction mixture was left stirring at room temperature overnight. The next day, H2NEt2 was isolated by filtration. + Cl - The salt was separated from the reaction mixture. The solvent was removed from the filtrate by vacuum distillation. As shown in Figure 7, 1 The remaining yellow residue (8 g, 38% yield) was confirmed to be Sn(OtBu)4 by 1 H NMR spectroscopy. EXAMPLES

[0087] Example 3: Synthesis of Sn(OiPr) Under an inert atmosphere, a 1 L reactor was charged with 49 g of iPrOH and approximately 400 mL of anhydrous benzene. The reactor contents were cooled to 0° C. and 450 g of SnCl was slowly added to the reactor via a dropper. HNMe2 gas was then passed through the reaction mixture for 4 hours with vigorous stirring. The reaction mixture was refluxed for 1 hour during the addition of HNMe2. The reaction mixture was left stirring at room temperature overnight. The next day, the H2NMe2 was isolated by filtration. + Cl - The salts were separated from the reaction mixture. The solvent was removed from the filtrate by vacuum distillation to leave the final product. EXAMPLES

[0088] Example 4: Synthesis of Sn(OEt) Under an inert atmosphere, a 1 L round bottom flask may be charged with 10 g of SnCl4 and approximately 400 mL of anhydrous hexane. The contents of the flask may be cooled in an ice / water bath, followed by slow addition of 16.6 mL of HNEt2 in 100 mL of anhydrous hexane to the reaction flask. The reaction mixture may then be stirred at room temperature for 2 hours and then cooled again in an ice / water bath. A solution of 15.4 mL of EtOH in approximately 50 mL of anhydrous hexane may then be added to the flask, and the reaction mixture may be left stirring at room temperature overnight. The next day, H2NEt2 is isolated by filtration. + Cl - The salt may be separated from the reaction mixture. The solvent may be removed from the filtrate by vacuum distillation. EXAMPLES

[0089] Example 5: Synthesis of Sn(OMe) Under an inert atmosphere, a 1 L round bottom flask may be charged with 10 g of SnCl4 and approximately 400 mL of anhydrous hexane. The contents of the flask may be cooled in an ice / water bath, followed by slow addition of 16.6 mL of HNEt2 in 100 mL of anhydrous hexane to the reaction flask. The reaction mixture may then be stirred at room temperature for 2 hours and then cooled again in an ice / water bath. A solution of 15.4 mL of MeOH in approximately 50 mL of anhydrous hexane may then be added to the flask, and the reaction mixture may be left stirring at room temperature overnight. The next day, H2NEt2 is isolated by filtration. +Cl - The salt may be separated from the reaction mixture. The solvent may be removed from the filtrate by vacuum distillation. EXAMPLES

[0090] Example 6: Synthesis of (MeO)3Sn(NMeEt) Under an inert atmosphere, a 1 L reactor was loaded with 25 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0° C., and 3.8 g of HNMeEt in about 100 mL of anhydrous hexane was added to the solution under vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0° C. 15.3 g of Sn(OMe)4 in about 200 mL of anhydrous benzene was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiOMe salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0091] Example 7: Synthesis of (EtO)Sn(NMe) Under an inert atmosphere, a 1 L reactor was loaded with 50 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0°C, and HNMe2 gas was passed through the solution for 30 min with vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0°C. 418.8 g of Sn(OEt) in about 200 mL of anhydrous benzene was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiOEt salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0092] Example 8: Synthesis of (EtO)3Sn(NMe2) Under an inert atmosphere, a 1 L reactor was loaded with 25 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0°C, and HNMe2 gas was passed through the solution for 30 min with vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0°C. 418.8 g of Sn(OEt) in about 200 mL of anhydrous benzene was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiOEt salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0093] Example 9: Synthesis of (EtO)Sn(NMeEt) Under an inert atmosphere, a 1 L reactor was loaded with 50 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0° C., and 7.5 g of HNMeEt in about 100 mL of anhydrous hexane was added to the solution under vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0° C. 418.8 g of Sn(OEt) in about 200 mL of anhydrous benzene was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiOEt salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0094] Example 10: Synthesis of (EtO)3Sn(NMeEt) Under an inert atmosphere, a 1 L reactor was loaded with 25 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0° C., and 3.8 g of HNMeEt in about 100 mL of anhydrous hexane was added to the solution under vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0° C. 418.8 g of Sn(OEt) in about 200 mL of anhydrous benzene was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiOEt salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0095] Example 11: Synthesis of CpSn(NMe2)3 Dicyclopentadiene dimer was decomposed using fractional distillation and prepared Cp-H was used the same day. In a glove box, a 1 L round bottom flask was loaded with 450.0 g of Sn(NMe2) and approximately 400 mL of anhydrous hexane. In a double manifold, 11.0 g of Cp-H was added to the reaction flask and the reaction mixture was refluxed with stirring for 3 hours. The solvent was removed in vacuum and the final material was isolated by reduced pressure distillation. EXAMPLES

[0096] Example 12: Synthesis of CpSn(NMeEt) Dicyclopentadiene dimer was decomposed using fractional distillation, and the prepared Cp-H was used the same day. In a glove box, a 1 L round bottom flask was loaded with 450.0 g of Sn(NMeEt) and approximately 400 mL of anhydrous hexane. In a double manifold, 9.3 g of Cp-H was added to the reaction flask, and the reaction mixture was refluxed with stirring for 3 hours. The solvent was removed in vacuum, and the final material was isolated by reduced pressure distillation. EXAMPLES

[0097] Example 13: Synthesis of Sn(NMeCH2CH2NMe)2 Under an inert atmosphere, a 1 L reactor was loaded with 62 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0 °C, and 7.11 g of NHMeCH2CH2NHMe was added to the solution with vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0 °C. 10.0 g of SnCl4 in about 200 mL of anhydrous hexane was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiCl salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0098] Example 14: Synthesis of Sn(N2C4H8)2 Under an inert atmosphere, a 1 L reactor was loaded with 62 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0 °C, and 6.94 g of piperazine was added to the solution with vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0 °C. 10.0 g of SnCl4 in about 200 mL of anhydrous hexane was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiCl salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0099] Example 15: Synthesis of Sn(MeNCH2CH2CH2NMe)2 Under an inert atmosphere, a 1 L reactor was loaded with 62 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0 °C, and 8.24 g of NHMeCH2CH2CH2NHMe was added to the solution with vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0 °C. 10.0 g of SnCl4 in about 200 mL of anhydrous hexane was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiCl salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0100] Example 16: Synthesis of Sn(MeNCH2CH2O)2 Under an inert atmosphere, a 1 L reactor was loaded with 62 mL of a 2.5 M nBuLi solution in hexane, and about 500 mL of anhydrous hexane. The reactor contents were cooled to 0 °C, and 6.05 g of NHMeCH2CH2OH was added to the solution with vigorous stirring. The reaction mixture was then stirred at room temperature for 1 h and then cooled again to 0 °C. 10.0 g of SnCl4 in about 200 mL of anhydrous hexane was added dropwise to the reaction mixture. The contents of the reaction flask were allowed to warm to room temperature and left stirring overnight. The next day, the LiCl salt was separated from the reaction mixture by filtration. The solvent was removed from the filtrate by vacuum distillation. The product was purified by distillation under reduced pressure. EXAMPLES

[0101] Example 17: Reactivity test Water was added to Sn(NMeEt)4. An exothermic reaction occurred immediately and white SnO2 solid was formed.

[0102] In a further test, methanol was added to Sn(NMeEt)4, which also caused an immediate exothermic reaction. Figure 8 shows the reaction of Sn(NMeEt)4 before and after the addition of MeOH. 1 The H NMR spectrum is shown in Figure 8. As shown in Figure 8, the final product shows the release of HNMeEt and complete consumption of the starting material. EXAMPLES

[0103] Example 18: Thermal stability test Thermal stability studies of Sn(NMeEt)4 were performed on stainless steel ampoules stored at constant temperatures of 60°C, 100°C, and 125°C for several weeks. NMR was performed to see if there was any thermal decomposition. Visual inspection was also used to look for solid formation after storage.

[0104] Sn(NMeEt)4 remained stable at 60° C. In particular, FIG. 9 shows the weight percent of Sn(NMeEt)4 compared to the weight percent of HNMeEt to demonstrate the stability of Sn(NMeEt)4 at a storage temperature of 60° C. FIG. 10 shows the stability of Sn(NMeEt)4 samples at 60° C. at 0, 4, and 9 weeks. 1 1 H NMR spectrum is shown.

[0105] Sn(NMeEt)4 showed little decomposition at 100 °C. In particular, Figure 11 shows the weight percent of Sn(NMeEt)4 compared to the weight percent of HNMeEt to demonstrate the stability of Sn(NMeEt)4 at a storage temperature of 100 °C. Figure 12 shows the stability of Sn(NMeEt)4 samples at 100 °C at 0, 4, and 9 weeks. 1 1 H NMR spectrum is shown.

[0106] Sn(NMeEt)4 was completely decomposed after 2 weeks at 100 °C. In particular, Figure 13 shows the decomposition of the Sn(NMeEt)4 sample at 125 °C at 0, 1, and 2 weeks. 1 1 H NMR spectrum is shown.

[0107] Higher vapor pressure also allows for minimal heating of the chemical for vapor delivery to the CVD / ALD chamber. Less volatile materials are heated to higher temperatures to reach a desired vapor pressure for physical delivery to the chamber. As temperatures increase, the likelihood of thermal decomposition increases. The goal for any precursor is to be delivered at a high enough vapor pressure without inducing thermal decomposition of the material. Figure 1 shows the various vapor pressures of several compounds that can be used to form tin oxide films.

[0108] It has also been found that it is difficult to keep a single reactive compound stable during storage. In particular, reactive compounds used to deposit tin oxide films have been found to disproportionate over time. Additives have been found to prevent dimer formation in such compounds. In particular, compounds of formula IV: Sn(NR 4 2) A second organometallic compound selected from the compounds represented by 4 has been found to provide the ability to inhibit dimer formation of the tin compound used to deposit the tin oxide film. In certain compounds included in formula IV, each R 4 The groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms.

[0109] Compounds of formula IV each R 4 Each R is an independently selected alkyl group having from 1 to 10 carbon atoms. 4 It is contemplated that the groups may be independently selected alkyl groups having 1 to 6 carbon atoms. In particular, each R 4 The R groups are independently selected alkyl groups having 1 to 4 carbon atoms. More specifically, each R 4 The groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. Also, in some compounds, each R 4 The groups may represent different alkyl, acyl, or aryl groups, especially different alkyl groups.

[0110] Specific organometallic compounds of formula IV include the following: Sn(NMe2)4, Sn(NEt2)4, and Sn(NMeEt)4.

[0111] Organometallic compounds that may benefit from the addition of a second organometallic compound of formula IV include those of formula III: 3 2Sn(NR 3 '2)2 (In the formula, Each R 3 The groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms; Each R 3 ' groups are independently selected from the group consisting of alkyl or aryl groups having 1 to 10 carbon atoms. The compound represented by the formula:

[0112] Compounds of formula I each R 3 Group and each R 3 Each R' group is an independently selected alkyl group having 1 to 10 carbon atoms. 3 Group and each R 3 It is contemplated that each R′ group may be an independently selected alkyl group having 1 to 6 carbon atoms. 3 Group and each R 3 Each R' group is an independently selected alkyl group having 1 to 4 carbon atoms. More specifically, each R 3 Group and each R 3 The R' groups are independently selected from the group consisting of methyl, ethyl, propyl, iso-propyl, tert-butyl, iso-butyl, and n-butyl. Also, in some compounds, each R 3 Group and each R 3 The ' groups may represent different alkyl, acyl or aryl groups, especially different alkyl groups. EXAMPLES

[0113] Example 19: Disproportionation Test Disproportionation stability studies of Me2Sn(NEtMe)2 with and without Sn(NMe2)4 were performed on stainless steel containers stored at a constant temperature of 70 °C for several days. NMR was performed to determine the mass % of Me2Sn(NEtMe)2 at various times during storage to see if there was any disproportionation. For comparison, Me2Sn(NEtMe)2 was stored alone in one container and Me2Sn(NEtMe)2 spiked with 10 mol% Sn(NMe2)4 was stored in another container. Figure 2 is a graph showing the disproportionation rate of Me2Sn(NMe2)2 alone versus in mixtures with Sn(NMe2)4.

[0114] The test results, as shown in FIG. 6, show that when Sn(NMe2)4 was added, the disproportionation was almost prevented and the storage stability was substantially improved.

[0115] In some cases, etching of the deposited tin oxide film is desired. Furthermore, as mentioned above, the deposition chamber used to form the tin oxide film needs to be cleaned, which includes removing the tin oxide film formed on the inner surface of the reactor chamber. It is desirable to use a dry etching method both to etch the tin oxide film formed on the substrate and to remove the unwanted tin oxide film from the inner surface of the reactor chamber. However, dry etching of tin oxide has proven difficult for the reasons listed above. However, the dry etching method disclosed herein solves these problems. An exemplary embodiment of the dry etching method is given below.

[0116] In use, the dry etching method includes heating the entire reactor chamber to an elevated temperature, for example, between 100° C. and 900° C., and supplying an etchant gas from a gas source coupled to the reactor chamber. More specifically, in embodiments of thermal etching in a quartz CVD / ALD furnace, the elevated temperature is between 400° C. and 900° C., while in embodiments of plasma etching in an aluminum, stainless steel, or ceramic ALD chamber, the elevated temperature is between 100° C. and 400° C. The etchant gas flows through the reactor chamber before being exhausted along with any reaction products generated and pumped out of the gas exhaust line. Gas pressure in the reactor chamber is typically maintained between 0.1 mBar and 1,000 mBar (atmospheric pressure), but can be as high as 1,500 mBar during a dry etching cycle.

[0117] In an embodiment, the etchant gas is activated to enhance the generation of free radicals and thereby enhance the etching process. Activation can be achieved by thermal activation, ultraviolet (UV) excitation, or plasma discharge. The etchant gas enters an activation chamber. In the activation chamber, the bulk gas is exposed to an activation energy source, such as a heater (thermal activation), a UV lamp (UV activation), or an ionizing RF field (plasma activation). Thermal activation can be achieved by heating the MOVPE (metal organic vapor phase deposition) reactor. Alternatively, the etchant gas can be preheated in a heating chamber before injection into the reactor. In the case of UV or plasma discharge activation, the etchant gas is activated in the activation chamber by exposure to UV light or radio frequency plasma discharge before injection into the reactor. The activated gas leaves the activation chamber through an exhaust port and enters the MOCVD (metal organic chemical vapor deposition) reactor chamber.

[0118] The etchant gas has the general formula A 3 OX2 (in the formula, A 3is C, N, or S, O is oxygen, and each X is independently selected from a halogen. For example, the etchant gas may include a carbonyl, thionyl, or nitrosyl group (CO, SO, or NO) combined with a halogen (i.e., chlorine, bromine, or iodine (Cl, Br, or I)). COCl2, COBr2, COI2, SOI2, SOCl2, SOBr2, SO2Cl2, SO2Br2, NOCl, NOBr, NOI, SOClBr, SOClF, and SOFBr are examples of suitable etchant gases. Etchant gases may be derived from neat materials or alternatively may be generated by the combination of separate components such as CO, SO, SO2, or NO mixed with Cl2, Br2, or I2. Etchant gases may be mixed with a carrier gas such as argon, nitrogen, or hydrogen. In the case of etchant components available in gaseous state, the etchant gas or its components may be supplied directly from one or more gas cylinders. In the case of etchant gas components that are normally in liquid state, the required gaseous state can be achieved by blowing a carrier gas into a vessel containing the liquid etchant components to volatilize the liquid components into etchants, thereby producing a mixture of carrier gas and etchant vapor. Alternatively, the liquid chemical components may be heated until vaporized, at which point the vapor may be combined with a carrier gas, if necessary, and introduced into the reactor chamber. The etchant gas may contain additional amounts of halogens to enhance etching. The etchant gas may contain additional amounts of methyl halides, hydrogen halides, or other halogen compounds to enhance etching.

[0119] In the reaction chamber, the etchant gas reacts with the metal-containing deposits to form volatile metal halides, which are removed by purging the etchant gas. A typical reaction involves the reaction of metal oxides with the purge gas to form metal halides with residual oxygen combining with carbonyl / thionyl / nitrosyl groups. For example: Ga2O3+3SOBr2→2GaBr3+3SO2 2Ga2O3+6SOBrCl→GaClBr2+GaBrCl2+GaCl3+GaBr3+6SO2 Ga2O3+3NOBr→GaBr3+3NO2 SnO2+2SOCl2→SnCl4+2SO2 Other metal-containing deposits also react to form metal halides. Oxides are some of the most difficult deposits to remove due to the strong affinity of metals for oxygen.

[0120] Once the metal halides are formed, they need to be removed from the reaction chamber. One method for removal is to apply a vacuum in the chamber to move the halides for removal from the reactor chamber. Another option, which can be used alone or in combination with applying a vacuum in the chamber, is to heat the chamber to a temperature sufficient to evaporate or sublime the halides.

[0121] It has been discovered that COCl2 can be particularly useful as an etchant gas for removing tin oxide and other difficult to remove metal oxides. However, phosgene gas (COCl2) is an exceptionally dangerous nerve agent. It has therefore been determined that by adding a gas mixture of SOCl2 or NOCl with CO or CO2, a similar etching function can be achieved as COCl2, but without the chemical hazards associated with COCl2.

[0122] In further embodiments, the etchant gas includes additives to enhance the etch rate, etch selectivity, or lifetime of by-products. Such additives include carbon or hydrogen-containing gases, such as those having the general formula C x H y O z (wherein x, y, and z are numbers from 0 to 10).

[0123] In further embodiments, the etchant gas may also contain diluent additives or carriers to enhance the etch rate, etch selectivity, or lifetime of by-products. Such additives may include relatively inert gases such as N2, Ar, He, Ne, etc.

[0124] The methods disclosed herein allow for low temperature etching of SnO2 and other metal oxides that are selective to quartz, oxides, ceramics, aluminum and other materials.

[0125] Additionally, the methods disclosed herein using the disclosed etchant gases form reaction by-products that are more volatile than the by-products produced by hydrogen-containing molecules, and therefore can be more easily evacuated from the chamber before redepositing on the chamber walls.

[0126] As shown in the examples below, the methods disclosed herein are also less corrosive than methods utilizing Cl2 as an etchant and do not attack aluminum surfaces. EXAMPLES

[0127] Example 20 Aluminum, anodized, and Viton specimens were immersed in 1.5 g of SOCl2 at 60°C. After two weeks no signs of change were observed. Some brown solids were loosely attached to the aluminum specimens, but the aluminum surface itself was unaffected and no further solids were observed after the first few days. Separately, three identical specimens were sealed in stainless steel ampoules containing 3 g of liquid chlorine and held at 60°C for two days. Little change was observed in the anodized aluminum; however, very little aluminum remained. The aluminum was essentially converted to a yellowish-beige solid. The Viton exhibited a significant loss of tensile strength and easily broke into two pieces when pulled from the yellowish-beige solid mass. A photograph of the above results is shown in Figure 3. EXAMPLES

[0128] Example 21: Effect of power on SnO2 etch rate at 26°C and 75°C Etching of substrates having an exposed layer of SnO2 on Si was performed. The substrates were prepared at 50°C and 330 Å. Each of the runs at 26°C had an etch time of 60 seconds, while each of the runs at 75°C had an etch time of 30 seconds. Each run included a flow rate of 2 sccm (vapor draw), with the pressure set at 350 mTorr (0.467 mBar). A graph of etch rate (Å / min) versus power (W) for the runs is shown in Figure 4. Also, Figure 5 is a graph of etch rate (Å / min) versus power (W) for only the runs where the temperature was 26°C.

[0129] As the results show, the etch rate of SnO2 increases exponentially with power. The effect of power on the etch rate increase at ambient temperature is similar between SnO2 and SiO2. However, no SiO2 etching was observed at 75°C and 100 W. Furthermore, the selectivity for SnO2 etching at 26°C at low pressure of 350 mTorr (0.467 mBar) is approximately 13:1, while at 1 Torr (1.333 mBar) it is 3:1. EXAMPLES

[0130] Example 22: Etch rate of SnO2 film at 300 W and 26°C Etching of substrates having an exposed layer of SnO2 on Si was performed. The substrates were prepared at 50°C and 330 Å. Each run had a temperature of 26°C, a flow rate of 2 sccm (vapor extraction), a pressure set at 350 mTorr (0.467 mBar), and a power of 300 W. Only the run time varied between runs, and the various resulting etch rates are shown in Table 1 below.

[0131] [Table 1] EXAMPLES

[0132] Example 23: Effect of power on SnO2 etch rate at 26°C Etching of substrates having an exposed layer of SnO2 on Si was performed. The substrates were prepared at 50°C and 330 Å. Each run included a temperature of 26°C, a flow rate of 2 sccm (vapor extraction), a pressure set at 350 mTorr (0.467 mBar), and an etch time of 60 seconds. Only the run time varied between runs, and the various resulting etch rates are shown in Table 2 below.

[0133] [Table 2] EXAMPLES

[0134] Example 24: Effect of power on SnO2 etch rate at 75°C Etching of substrates having an exposed layer of SnO2 on Si was performed. The substrates were prepared at 50°C and 330 Å. Each run included a temperature of 75°C, a flow rate of 2 sccm (vapor extraction), a pressure set at 350 mTorr (0.467 mBar), and an etch time of 30 seconds. Only the run time varied between runs, and the resulting various etch rates are shown in Table 3 below.

[0135] [Table 3] EXAMPLES

[0136] Example 25: Effect of Temperature on SnO2 Etch Rate Etching of substrates having an exposed layer of SnO2 on Si was performed. The substrates were prepared at 50°C and 330 Å. Each run included a flow rate of 2 sccm (vapor extraction), a pressure set at 350 mTorr (0.467 mBar), an etch time of 30 seconds, and a power of 200 W. Only the run time varied between runs, and the resulting various etch rates are shown in Table 4 below.

[0137] [Table 4]

[0138] Multi-Stage Distillation From theoretical modeling of the activation energy required to remove the ligand from the molecule via hydrolysis reaction, a wide range of activation energies is observed between the molecules. Thus, differences in reactivity are observed. This indicates that a molecule with a low activation energy may be a more reactive molecule to form SnO2, but this value also indicates that the molecule may be more prone to decomposition and reaction during the synthesis and purification process. Therefore, it may be difficult to obtain pure compounds within the range of formulas I and II, especially to obtain assay purities of more than 95% or even more than 99%.

[0139] However, using multiple stage vacuum distillation, assay purities of greater than 95% and even greater than 99% can be obtained for compounds in the range of formula I or II. Although various forms of multiple stage distillation are known in the chemical manufacturing industry, they have not been used for the purification of organometallic materials, including compounds of formula I or II.

[0140] Multiple effect or multi-stage distillation (MED) is a distillation process often used for seawater desalination, as illustrated by the schematic diagram shown in FIG. 14. The process consists of multiple stages or "effects." (In the schematic diagram in FIG. 14, the first stage is at the top. The upper region of each stage is vapor and the lower region of each stage is liquid feed. The material flowing through the pipes at the bottom of the VC along the left side of the diagram is condensate. It is not shown how the feed enters the stages other than the first, but it should be easy to understand how. F-feed. S-heating steam in. C-heating steam out. W-purified material (condensate) out. R-waste material out. O-refrigerant in. P-refrigerant out. VC is the final stage cooler.) At each stage, the feed is heated by steam in the tubes. Part of the feed evaporates and this steam flows into the tubes of the next stage to heat and evaporate more distillate. Each stage essentially reuses energy from the previous stage.

[0141] The system can be seen as a series of closed spaces separated by tube walls, with a heat source at one end and a heat sink at the other. Each space is at a pressure below atmospheric pressure by a vacuum. Each space consists of two communicating subspaces: the outside of the tube in stage n, and the inside of the tube in stage n+1. Each space has a lower temperature and pressure than the previous space, and the tube walls are at a temperature intermediate between the temperatures in the fluid on either side. The pressure in a space cannot be equilibrated with the temperatures of the walls of the subspaces on either side, resulting in an intermediate pressure. As a result, the feed material evaporates because the pressure in the first subspace is too low or the temperature is too high. In the second subspace, the pressure is too high or the temperature is too low, causing the vapor to condense. This transfers the energy of evaporation from the warmer first subspace to the cooler second subspace. In the second subspace, the energy flows by conduction through the tube walls to the next, cooler space.

[0142] Although described in connection with preferred embodiments, it will be understood by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. Formula I: Q ｘ -Sn-(NR １’ 2) ４－ｘ Formula I (In the formula, Q is OR １ or Cp, Each R １ The groups are independently selected from the group consisting of alkyl groups and aryl groups having 1 to 10 carbon atoms; Each R １’ The groups are independently selected from the group consisting of alkyl or acyl groups having 1 to 10 carbon atoms and aryl groups; x is an integer from 1 to 3. Organometallic compounds.

2. Q is OR １ 2. The organometallic compound of claim 1 ,

3. 2. The organometallic compound of claim 1, wherein Q is Cp.

4. 4. The organometallic compound of claim 3, wherein x is 1.

5. Each R １’ 5. The organometallic compound of any one of claims 1 to 4, wherein the groups are independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms.

6. Each R １’ 6. The organometallic compound according to claim 1, wherein the group is Me.

7. Each R １’ 6. The organometallic compound of claim 1, wherein the radicals represent a combination of two different alkyl, acyl, or aryl groups.

8. Each R １ The organometallic compound of any one of claims 1, 2 and 5-7, wherein the groups are independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms.

9. At least one R １ 9. The organometallic compound of any one of claims 1, 2 and 5 to 8, wherein the group is t-Bu or i-Pr.

10. (MeO) ２ Sn(NMe ２ ) ２ , (MeO) ２ Sn(NEtMe) ２ , (MeO) ３ Sn(NMe ２ ), (MeO) ３ Sn (NEtMe), CpSn (NMeEt) ３ , and CpSn(NMe ２ ) ３ 2. The organometallic compound of claim 1 selected from the group consisting of:

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