Use of water and acidic water to purify liquid MOCVD precursors

Details Use of water and acidic water to purify liquid MOCVD precursors Use of water and acidic water to purify liquid MOCVD precursors

2001-12-27

2003-03-18

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C556S012000, C556S040000, C556S112000, C556S117000, C427S587000

Reexamination Certificate

active

06534666

ABSTRACT:

BACKGROUND OF THE INVENTION
In the electronics industry there is a steady trend towards manufacturing microprocessors of increasingly high speed and large information storage capacity. This requires the individual electrical devices such as transistors, etc. within the microprocessors to be fabricated at an increasingly small scale. The metallic electrical interconnects between the devices also need to be miniaturized. As device and interconnect dimensions fall below one-quarter of a micron, the choice of interconnect metal becomes critical.
A process for producing these microscopic metal features found in microprocessors and interconnects is CVD (Chemical Vapor Deposition). In this technique a volatile organometallic (OM) compound in the gas phase is contacted with areas of a circuit where growth of a metal film (i.e. interconnect) is required. A surface catalyzed chemical reaction then occurs which leads to deposition of the desired metal. Since this is a chemical reaction, there is a potential for it to provide surface selective metallization.
Chemical vapor deposition of copper metal using organometallic copper compounds has been widely used in the electronics industry for the above applications. One class of copper organometallics for this application is the copper+1 (&bgr;-diketonate)(L) complexes where (L) represents a suitable stabilizing ligand, typically a non-aromatic unsaturated group including silylolefins and silylalkynes. Typically, in the synthesis of copper+1 (&bgr;-diketonate)(L) complexes, the divalent by-product copper bis(&bgr;-diketonate) and unreacted &bgr;-diketone species can be encountered as impurities that need to be removed.
The following patents are representative of organometallic compounds for chemical vapor deposition in the electronics industry.
U.S. Pat. No. 5,085,731 discloses organometallic complexes base upon copper
+1
(&bgr;-diketonate) (L) complexes where (L) is a silylolefin stabilizing ligand. These are represented by the formula:
wherein R
1
and R
3
are each independently C
1
-C
8
perfluoroalkyl, R
2
is H, F or C
1
-C
8
perfluoroalkyl, R
4
is H, C
1
-C
8
alkyl, or Si(R
6
)
3
, each R
5
is independently H or C
1
-C
8
alkyl, and each R
6
is independently phenyl or C
1
-C
8
alkyl. One type of complex is prepared by reacting a copper salt, e.g., copper chloride, the potassium salt of hexafluoroacetylacetone(i.e. K
+
(hfac)), and a silylolefin in hexane or other solvent.
U.S. Pat. No. 5,187,300 discloses organometallic copper complexes suited for selectively depositing copper films onto electrically conducting portions under CVD conditions. The copper complexes are based upon copper(+1)(&bgr;-diketoneonate)(L) where (L) is a silylalkyne stabilizing ligand. One type of complex is prepared by the reaction of the potassium salt of hexafluoroacetylacetone with copper chloride in the presence of a silylalkyne stabilizing ligand. These complexes have the formula:
wherein R
1
and R
3
are each independently C
1
-C
8
perfluoroalkyl, R
2
is H, F or C
1
-C
8
perfluoroalkyl, R
4
is H, C
1
-C
8
alkyl, phenyl, or Si(R
5
)
3
, and each R
5
is independently H or C
1
-C
8
alkyl or phenyl.
U.S. Pat. No. 5,098,516 discloses organo copper based ligands of the formula:
wherein R
1
and R
3
are each independently C
1
-C
8
perfluoroalkyl, R
2
is H or C
1
-C
8
perfluoroalkyl and L is carbon monoxide, an isonitrile or an unsaturated hydrocarbon ligand containing at least one non-aromatic unsaturation. These compounds are also prepared by the reaction of the potassium salt of hexafluoroacetylacetone with copper chloride in the presence of a stabilizing ligand.
U.S. Pat. No. 6,096,913 discloses the synthesis of copper(+1)(&bgr;-diketoneonate)(L) type complexes by the reaction of &bgr;-diketone with cuprous oxide in the presence of stabilizing ligand (L) and finely divided copper powder to suppress the formation of unwanted copper bis (hexafluoroacetylacetonate). The process is described by the following equation:
2Hfac+Cu
2
O+2(A)=2copper+(hfac)(A)+H
2
O
BRIEF SUMMARY OF THE INVENTION
This invention relates to a streamlined and cost effective process for the purification of Cu(+1)(&bgr;-diketonate) (L) liquid and solid complexes which are suitable for the chemical vapor deposition of copper. Solid Cu(+1)(&bgr;-diketonate) (L) complexes can be purified using this technique by first dissolving them in a suitable inert solvent then subjecting this solution to the treatment described below for liquid precursors.
In the basic process for preparing Cu(+1)(&bgr;-diketonate) (L) complexes, sometimes referred to as a monovalent copper &bgr;-diketone complex product, a reactive copper compound is treated with a coordinating anion such as the anion of hexafluoroacetylacetone or other coordinating anion such as a fluorinated &bgr;-ketoimine anion and, if required, a stabilizing ligand (L), typically bearing at least one unsaturation that is olefinic or acetylenic or is an amine or a phosphine. Depending upon the reactants employed, a monovalent copper based complex of a p-diketone represented by the formula below is generated:
where n is 1 and z is 1. Optionally, as shown, the complex is stabilized with a neutral ligand designated (L) as shown. L is selected from the group consisting of trimethylvinylsilane, alkenes, dienes, silicon substituted alkenes, silicon substituted dienes, alkynes, silicon substituted alkynes, alkyne-alkenes, silicon substituted alkynes-alkenes, nitriles, silicon substituted nitrites, isonitriles, silicon substituted isonitriles, carbon monoxide, trialkyl phosphines, triaryl phosphines, imines, diimines, amines and mixtures thereof.
Representative complexes are shown in formulas 2-4 when &bgr;-diketone coordinating anions are used:
wherein R
1
and R
3
are each independently C
1
-C
8
fluoroalkyl, R
2
is H, F or C
1
-C
8
fluoroalkyl, R
4
is H, C
1
-C
8
alkyl, or Si(R
6
)
3
, each R
5
is independently H or C
1
-C
8
alkyl and each R
6
is independently phenyl or C
1
-C
8
alkyl;
wherein R
1
and R
3
are each independently C
1
-C
8
fluoroalkyl, R
2
is H, F or C
1
-C
8
fluoroalkyl, R
4
is H, C
1
-C
8
alkyl, or Si(R
5
)
3
, and each R
5
is independently H or C
1
-C
8
alkyl or phenyl; and,
wherein R
1
and R
3
are each independently C
1
-C
8
fluoroalkyl, R
2
is H or C
1
-C
8
fluoroalkyl and L is carbon monoxide, an isonitrile or an unsaturated hydrocarbon ligand containing at least one non-aromatic unsaturation.
Preferably, the fluoroalkyl groups in Formulas 2-4 are perfluoroalkyl.
In the syntheses of all of the above compounds it is typical for the crude reaction mixture to be contaminated with some divalent copper bis(&bgr;-diketonate) byproduct, sometimes referred to as divalent copper &bgr;-diketone complex byproduct, along with unreacted residual &bgr;-diketonate species either as free &bgr;-diketone or &bgr;-diketonate as a metal salt.
The improvement for removing unreacted fluorinated &bgr;-diketonate, e.g., Hhfac or the &bgr;-diketonate salt, e.g., Khfac from the reaction mixture comprises the following: contacting the reaction mixture with an effective amount of deionized water, preferably a degassed, and, most preferably, deoxygenated water, for solubilizing and extracting the unreacted fluorinated &bgr;-diketonate species into an aqueous phase. In the preferred case, which includes the removal of the divalent copper &bgr;-diketone complex by-product from the reaction mixture containing the monovalent copper(+1) (&bgr;-diketonate) (L) complex product, as well as other impurities, the process comprises: contacting the reaction product with a mixture of an acid and deoxygenated water under conditions for forming a water soluble divalent copper salt. The resulting aqueous phase is then separated thereby removing both the unreacted fluorinated &bgr;-diketonate species and the divalent copper bis(&bgr;-diketonate) by-product from the monovalent copper(+1) (&bgr;-diketonate) (L) complex product. Additionally, if cuprous oxid

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