Patent Application
20100130779
The semiconductor fabrication industry continues to source metal containing precursors for chemical vapor deposition processes, including atomic layer deposition, for fabricating conformal metal containing films on substrates, such as; silicon, metal nitride, metal oxide and other metal-containing layers, using these metal-containing precursors. Barium and strontium containing precursors are especially sought after for the deposition of thin barium and strontium oxide containing thin films for advanced memory device manufacture. The prior art has attempted to provide precursors for these applications, as set forth below. However, none of the metal complexes in the prior art share the special characteristic of the complexes disclosed in this invention.
Relevant prior art includes:
The present invention is a metal ligand having at least one 1,3,5-triazapentadienate ligand having aliphatic side chains on the 1- and 5-nitrogen atoms, where at least one aliphatic side chain is functionalized with an oxygen or nitrogen atom that coordinates with the metal, the 1- and 5-nitrogen atoms coordinate with the metal and the metal is selected from the group consisting of magnesium, calcium, strontium, barium and radium.
The present invention is also a method of depositing a Group 2 metal on a semiconductor substrate comprising contacting the substrate with a metal ligand having at least one 1,3,5-triazapentadienate ligand having aliphatic side chains on the 1- and 5-nitrogen atoms, where at least one aliphatic side chain is functionalized with an oxygen or nitrogen atom that coordinates with the metal, the 1- and 5-nitrogen atoms coordinate with the metal and the metal is selected from the group consisting of magnesium, calcium, strontium, barium and radium.
In contrast to the prior art precursors described above, the compounds of the present invention have aliphatic side chains attached to the 1,5 position nitrogen atoms of a 1,3,5-triazapentadienate ligand functionalized with oxygen and nitrogen atoms. These groups, being anchored to the main body of the triazapentadinate ligand can then coordinate to the metal center to provide a large coordination sphere around the metal center.
This stabilizes the complex and permits monomeric metal complexes to form, especially in the case of barium, which has a tendency to form dimeric, tetrameric or polymeric complexes of lesser utility as precursors due to their high molecular weight. In the prior art mentioned above, no descriptions of group 2 triazapentadienate complexes are made. Indeed, these new molecules are absent from the chemical and patent literature, as is their use as volatile metal sources for chemical vapor deposition (“CVD”), atomic layer deposition (“ALD”) etc. In addition, those triazapentadienate metal compounds which are described do not contain coordinating oxygen or nitrogen groups in the organic groups attached to the terminal nitrogen atoms in positions 1 and 5 which can then coordinate to the metal center to provide a larger coordination sphere for the metal, as is particularly desirable in the case of barium and strontium compounds. This is similar to the situation found when diketimine ligands are used for Group 2 presursors, i.e., the groups attached to the diimine nitrogen atoms are simple alkyl groups or alkyl substituted aromatics with no coordinating nitrogen or oxygen atoms.
Copper (+1) and lithium (+1) 1,3,5-triazapentadienate compounds are described in Inorg. Chem., (47), 2008 where the groups attached to the terminal 1, 5 nitrogens are Si(Me)3 bearing no oxygens or nitrogens. Manganese (+2), copper (+2), iron (+2), cobalt (+2) and lithium 1,3,5-triazapentadienes are described in Inorg. Chem. (47), 6692-6700 with hydrogen, Si(Me)3, phenyl or 2,6 disopropylphenyl groups attached to the terminal 1,5 nitrogen atoms, but these goups bear no coordinating nitrogen or oxygen atoms. Nickel (+2) 1,4,5-triazapentadienyl compounds are described in Euro. J. Inorg. Chem, 2004, 267 where the terminal 1,5 nitrogen atoms are functionalized with Si(Me)3 groups rather than organic groups bearing coordinating nitrogen or oxygen atoms. Palladium (+2) 1,3,5-triazapentadienyl compounds are described in Euro J. Inorg. Chem 2006, 3634 where the terminal 1,5 nitrogen atoms bear only hydrogen groups rather than organic groups bearing coordinating oxygen or nitrogen atoms. Fluorinated 1,3,5-triazapentadienate of the metals manganese, iron, cobalt, copper, nickel zinc and palladium are reported in Inorg. Chem. 2003 (42) 932-934 but only phenyl groups with no coordinating oxygen or nitrogen atoms are substituted onto the terminal 1,5-nitrogen atoms. Lithium potassium and sodium 1,3,5-triazapentadienyl compounds are described in Inorg. Chem. (42) 2596-2601 but the groups on the terminal 1,5 nitrogens are only phenyl with no oxygen or nitrogen atoms. A fluorinated 1,3,5-triazapentadienly mercury compound is reported in Organometallics, 2004, (23), 2281-2286, but only phenyl groups with no oxygen or nitrogen atoms are substituted on the 1,5 nitrogens. Highly fluorinated copper (+1) 1,3,5-triazapentadienyl compounds are described in Inorg. Chem. (45) 8859-8861 (2006), but the groupos on the 1,5 nitrogens are perfluorinated aryl or aryl functionalized with fluorine and trifluoromethyl groups with no coordinating oxygen or nitrogen groups. Silver 1,3,5-triazapentadienyl compounds are described in Inorg. Chem. (43) 7396-7402 (2004) but the groups on nitrogens 1 and 5 are 2,6-diisopropylphenyl with no oxygen or nitrogen substituents. Copper (+1) 1,3,5-triazapentadienyl compounds with only 2,6-diisopropyl phenyl groups on the 1,5 nitrogens are reported in Inorg. Chem. (43) 5786-5788 (2004).
For instance, in the case where the triazapentadiene ligand anion [Me2NC(NCPh)NC(NPh)NMe2]— would coordinate to barium, there are no coordinating oxygen atoms and no additional nitrogen atoms beyond the nitrogen atoms of the 1,3,5-triazapentediene ligand.
By contrast, the precursors of the present invention are based upon 1,3,5-traiazapentadiene ligands that provide an array of coordinating oxygen and nitrogen groups, which can wrap around and encapsulate the metal center. However, the group 2 metal complexes of this disclosure also include 1,3,5-triazapentadiene complexes, where the groups substituted on the 1,5-nitrogens contain no coordinating oxygen or nitrogen groups.
This invention is directed to metal containing polydentate 1,3,5-triazapentadienates and their solutions for vapor delivery by direct liquid injection, wherein the polydentate 1,3,5-triazapentadienates incorporate nitrogen or oxygen functionality by attaching them to the 1,5 nitrogens of the 1,3,5-triazapentadiene ligands, as metal coordinating side chains. It also includes a novel method of synthesizing 1,3,5-triazapentadiene ligands in high yield and high purity, using novel synthetic strategies for incorporating the coordinating side arm groups, which contain nitrogen and oxygen atoms.
Besides the 1,3,5-triazapentadiene ligands with coordinating side arms, other composition are described where sterically encumbered groups, such as t-butyl are substituted at the 1,5 nitrogen atoms. In this configuration, the resulting metal complexes, such as barium complexes will be forced to adopt novel coordination modes to the 1,3,5-triazapentadiene ligands resulting in monomeric volatile species. Additionally, the groups substituted onto the nitriles used in the ligand synthesis are chosen so that they contain oxygen or nitrogen groups, which will coordinate to and stabilize the barium center. The new 1,3,5-triazapentadiene ligands include, but are not limited to: Me2NC(NCH2CH(OMe)2)NC(NHCH2CH(OMe)2)NMe2; and Me2NC(NCH2CH2OMe)NC(HNCH2CH2OMe)NMe2.
The new metal complexes of this disclosure are characterized by 1,3,5-triazapentadienyl ligands, which contain additional coordinating atoms beyond the two 1,5 positioned nitrogen atoms of the 1,3,5-triazapentadienyl ligands, so as to provide a coordination sphere for the metal center. In this way, the entire coordination sphere is an integral part of the structure of the resulting metal complex. The polydentate metal 1,3,5-triazapentadienate complexes are selected from the group represented by the structures:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, radium, preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1-3,5 are individually selected from the group consisting of alkyl fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms; preferably R1-5 contains 2 or 3 carbon atoms, thus making a R five- or six-member coordinating ring to the metal center; In addition, groups R1 can be connected to R2, R3, or R5 to form rings.
The structure of bis(1,5-bisN,N′(methoxyethyl)-2,4-bis(dimethylamido)-1,3,5-triazapentadienate) barium, a specific example of the formulations illustrated by structure A, is shown below.
In addition, groups R2, R3, R4 or R5 from one 1,3,5-triazapentadienly ligand can be connected to the same groups on the other 1,3,5-triazapentadienly ligand.
Additional nitrogen linkages can be contemplated as shown in B, below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium and radium, preferably strontium and barium. A variety of organo groups may be employed, as for example, wherein R1,7 are selected from the groups consisting of alkyl fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy, having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms, preferably R2,5 contains 2 or 3 carbon atoms, thus making a five- or six-member coordinating ring to the metal center. In addition, group R1 can be connected to R2,3,4,5,6, to form ring structures. Also, R3, R4, R6 and R7 from one 1,3,5-triazapentadiene ligand can be connected to the same groups on the other 1,3,5-triazapentadiene ligand.
Alternate oxygen linkages can be contemplated as shown in C, below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1,3 is selected from the group consisting of hydrogen, alkyl, and fluoroalkyl having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, cycloaliphatic and aryl, having from 4 to 10 carbon atoms; R2 is selected from the group consisting of hydrogen, alkyl and alkoxy having from 1 to 10 carbon atoms, nitro, acyl and aryl having from 6 to 10 carbon atoms. R1, R2 and R3 can also be connected to form rings. R4,7 are individually selected from the group consisting of alkyl and fluoroalkyl having from 1 to 10 carbon atoms, and aryl having from 6 to 10 carbon atoms, preferably R4,7 contains 2 or 3 carbon atoms, thus making a five- or six-member coordinating ring to the metal center; R5,6,8,9 are individually selected from the group consisting of alkyl and fluoroalkyl having from 1 to 10 carbon atoms, cycloaliphatic and aryl having from 4 to 10 carbon atoms, and they can be connected to form a ring containing carbon, oxygen, or nitrogen atoms. groups R4, R5 or R6 can be connected to R7, R8 or R9 of the same diketimine ligand or to R4, R5, R6, R7, R8 or R9 of the other diketimine ligand. Similarly, R6, R7 or R9 can be connected to the same groups in the other ligand. In addition, R1 can also be attached to R2, R7, R8 and R9; R3 can be attached to R2, R4, R5 or R6.
Separate ether linkages to carbon are contemplated for the chelating oxygens, as shown in D, below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, radium, preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1-,9 is selected from the group consisting of alkyl, fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms and groups R1 to R9 can be connected together to form rings. Additionally, groups R1-R9 can be connected any of the corresponding groups in the other 1,3,5-triazapentadiene ligand found in the metal complex
Heterocyclic chelating complexes similar to epoxides are contemplated in E, as shown below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium or radium, preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1-3 is selected from the group consisting of alkyl, fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms preferably R3 contains 1 or 2 carbon atoms, thus making a five- or six-member coordinating ring to the metal center; n=4, 5, 6.
In addition, group R1 to R4 can be connected to together to form ring structures. In addition, any of these same groups can be connected to their counterparts in the other 1,3,5-triazpentadienyl ligand of the metal complex
Ligands can be bound not only to the metal center but to each ligand through an organic linkage, such as shown in F, below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, radium preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1-6 is selected from the group consisting of alkyl, fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms, preferably R5 contains 2 or carbon atoms, thus making a five- or six-member coordinating ring to the metal center.
Alternatively, R4 can also contain ether or amine groups, which can also coordinate to the metal center. In addition, groups R1, R2, R3, R5 and R6 can also be connected.
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, radium, preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1-9 is selected from the group consisting of alkyl, fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms, preferably groups R4/R10 and R8/R9 constitutes 2 or 3 carbon atoms, thus making a five- or six-member coordinating ring to the metal center.
Additionally, R5 can also contain ether or amine groups which can also coordinate to the metal center. R1, R2, R3, R4, R6, R7, R8, R9 and R19 can also be connected together.
Ligands that have additional nitrogen chelating functionality, as well as organic linkage between the ligands is contemplated, as in H, below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, radium preferably strontium and barium. A variety of organo groups may be employed as for example wherein R1-8 is selected from the group consisting of alkyl, fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms; preferably R4,6 contains 2 or 3 carbon atoms, thus making a five- or six-member coordinating ring to the metal center.
Alternatively, R5 can also contain ether or amine groups which can also coordinate to the metal center. R1, R2, R3, R4, R6, R7, R8 can be connected.
Further nitrogen chelating functionality beyond what is previously described are envisioned in I, below:
wherein M is a Group 2 metal selected from the group consisting of magnesium, calcium, strontium, barium, radium, preferably strontium and barium. A variety of organo groups may be employed, as for example, wherein R1-11 are selected from the group consisting of alkyl, fluoroalkyl, silylalkyl, alkoxy, silylalkoxy and fluoroalkoxy having from 1 to 10 carbon atoms, preferably a group containing 1 to 6 carbon atoms, aryl, fluoroaryl, silylaryl, cycloaliphatic and aryl, having from 4 to 10 carbon atoms. Preferably R groups 5/12, 7/17 constitute a 2 or 3 carbon atom linkage, thus making a five- or six-member coordinating ring to the metal center
Alternatively, R6 can also contain ether or amine groups, which can also coordinate to the metal center.
where R1 can be alkyl, fluoroalkyl, ary, fluoroalkyl, alkoxy, fluoroalkoxy, alkyl amine. R2 is a bulky alkyl group, such as; t-butyl, which contains no metal coordinating atoms, such as; nitrogen or oxygen. R3 can also be a bulky group, which contains no metal coordinating atoms, such as; nitrogen or oxygen; or alternatively, it can be hydrogen or an alkyl or aryl group, which does contain a coordinating group, such as; oxygen or nitrogen, as exemplified in the compounds A through I, above. In the structures(J) the 1,3,5-triazapentadiene ligand may coordinate ‘sideways’, whereby the metal center, such as barium, is positioned between two ligand anions, such that it is above the plane of one anion and below the plane of the other.
In addition to the above complexes, while not wishing to be bound by theory, mixed barium complexes can also be made, where two different 1,3,5-triazapentadiene anions are coordinated to a metal center or where one 1,3,5-triazapentadiene anion and one other organic or inorganic anion coordinate to barium to make a complete complex. Examples of such alternative anions include, but are not limited to, diketiminates, beta-diketonates, acetates, ketoiminates, alkoxides, amides, hydrides, beta-ketoesters, amidinates, guanidinates, cyclopentadienyl, cyanide, isocyanide, formate, oxalate, malonate, phenoxide, thiolate, sulfide, nitrate, alkyl, silylalkyl, fluoroalkyl, aryl, alkoxide, hydride.
Several advantages can be achieved through these metal-containing polydentate 1,3,5-triazapentadiene as precursors for chemical vapor deposition or atomic layer deposition, and these include:
Additionally, metal complexes can also be made by coordinating two different carefully chosen 1,3,5-triazapentadiene anions to a metal center, such as barium, such that the two ligands experience an optimal ‘fit’ or ‘interlock’ with each other and around the metal in such a way as to provide an adequate coordination sphere to create a stable monomeric complex.
The present patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/116,653 filed Nov. 21, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61116653 | Nov 2008 | US |
