Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2000-12-04
2002-01-22
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S028000, C556S031000, C556S040000, C556S045000, C556S057000, C556S087000, C556S137000, C556S146000, C556S147000, C556S465000, C556S466000, C556S095000, C427S248100, C427S255280, C427S585000
Reexamination Certificate
active
06340768
ABSTRACT:
FIELD OF INVENTION
This invention relates to organometalloid compounds and metal complexes thereof, which are of use for chemical vapor deposition processes and in other chemical processes.
BACKGROUND OF THE INVENTION
As the microelectronics industry moves into ultralarge scale integration (ULSI), enhancement in performance speeds of integrated circuits will be achieved by reducing the device feature size and thereby the overall die size. As a result, density constraints will require multilevel structures with vertical interconnects. It is expected that the use of metals with lower resistivity, such as gold, silver and especially copper, will be necessary because of the submicron geometries.
Fabrication of interconnect structures includes one or more metallization steps. Metallization is commonly accomplished by physical vapor deposition (PVD) processes, including evaporating and sputtering. Chemical vapor deposition (CVD) processes have an advantage over these so-called “line of sight” processes in the fabrication of submicron vertical interconnects because conformal layers of metals are more easily produced.
In CVD, a volatile precursor, usually a complex of a metal with an organic ligand, serves as a source of the metal. The precursor is delivered to the substrate in the vapor phase and decomposed on the surface to release the metal. The precursor must exhibit sufficient thermal stability to prevent premature degradation or contamination of the substrate and at the same time facilitate easy handling. Vapor pressure, the adsorption/desorption behaviour, the chemical reaction pathways, and the decomposition temperature can directly affect the purity of the deposited metal film and the rate of thin-film formation.
CVD precursors very frequently are based on complexes of metals with &bgr;-diketonates such as 2,2,6,6-tetramethyl-3,5-heptanedione (thd) and acetylacetonate (acac) and fluorinated b-diketonates, such as 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (hfa or hfac) and 2,2-diethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (fod). Volatility of the non-fluorinated precursors is insufficient for many applications. The fluorinated analogs possess greater volatility, but also have a tendency to fragment, a consequence of fluorine migration/carbon-fluorine bond cleavage at elevated temperatures, leading to contamination of the substrate. Consequently, a need exists for precursors which retain volatility yet release the metal without degradation of the ligand and for ligands which are not labile or disposed toward fragmentation.
It is therefore an object of this invention to develop metal complexes for CVD precursors that are highly volatile and yet stable at the sublimation point and also retain desirable processing features. It is a further object to develop ligands for use in CVD precursors which can induce high volatility in a metal and can release the metal without degradation of the ligand. It is a further object to provide new synthetic routes for the synthesis of these ligands from commercially available starting materials in good yields.
SUMMARY OF THE INVENTION
It has been surprisingly discovered that certain organic compounds containing silicon, germanium, tin or lead, when complexed with a metal, can induce high volatility in the metal complex. The resulting complexes are stable at the sublimation point and retain desirable processing features. The compounds have the structure of formula I:
wherein
R
1
is C
2
or higher alkyl, substituted alkyl, haloalkyl, cycloalkyl, C
7
or higher aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, acyl, alkyl carboxylate, aryl carboxylate, alkenyl, alkynyl, or E
2
(R
6
)(R
7
)(R
8
);
R
2
is H, halogen, nitro, or haloalkyl;
E
1
and E
2
are independently Si, Ge, Sn, or Pb;
R
3
, R
4
, R
5
, R
6
, R
7
, and R
8
are independently chosen from alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl, alkoxy, alkenyl, alkynyl or R
4
and R
5
, or R
7
and R
8
taken together form a divalent alkyl radical;
Y and Z are independently O, S or NR
9
; and
R
9
is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.
The present invention also relates to metal-ligand complexes that are highly volatile and yet stable at the sublimation point. The complexes also retain desirable processing features. The metal complexes of the present invention have the structure of formula II:
ML
n
·pD (II)
wherein
M is a metal chosen from the group consisting of: Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Ti, Zr, Hf, Pr, V, Nb, Ta, Nd, Cr, Mo, W, Mn, Re, Sm, Fe, Ru, Eu, Os, Co, Rh, Ir, Gd, Ni, Pd, Pt, Tb, Cu, Ag, Au, Dy, Ho, Al, Ga, In, Tl, Er, Ge, Sn, Pb, Tm, Sb, Bi, Yb, Lu, Th, and U;
D is a neutral coordinating ligand;
n is equal to the valence of M;
p is zero or an integer from 1 to 6; and
L is a compound of formula III:
wherein
R
1
is alkyl, substituted alkyl, haloalkyl, cycloalkyl, aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, acyl, alkyl carboxylate, aryl carboxylate, alkenyl, alkynyl, or E
2
(R
6
)(R
7
)(R
8
);
R
2
is H, halogen, nitro, or haloalkyl;
E
1
and E
2
are independently Si, Ge, Sn, or Pb;
R
3
, R
4
, R
5
, R
6
, R
7
, and R
8
are independently chosen from alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl, alkoxy, alkenyl, alkynyl or R
4
and R
5
, or R
7
and R
8
taken together form a divalent alkyl radical;
Y and Z are independently O, S or NR
9
; and
R
9
is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.
In another aspect, the present invention relates to a method of depositing a metal-containing layer on a substrate comprising vaporizing a metal-ligand complex of formula II and decomposing the metal-ligand complex in the presence of the substrate.
In yet another aspect, the present invention relates to ligands having haloalkyl-substituted metalloid substituents, particularly fluoroalkyl-substituted. In this case, R
3
, R
4
, R
5
, R
6
, R
7
, and R
8
are independently alkyl or haloalkyl, and at least one of R
3
, R
4
, R
5
, R
6
, R
7
, and R
8
is haloalkyl.
New synthetic routes for the synthesis of the ligands of formula I from commercially available starting materials in good yields have been discovered. In yet another aspect, the present invention relates to processes for preparing the ligands of formula I and metal complexes of formula II.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to organometalloid compounds that confer volatility on a metal when complexed therewith. Metalloids are defined herein as the elements silicon, germanium, tin and lead. Organometalloids are defined as compounds containing one or more metalloid atoms bonded to a carbon atom. The organometalloid compounds of the present invention have the structure of formula I:
wherein
R
1
is C
2
or higher alkyl, substituted alkyl, haloalkyl, haloalkyl, cycloalkyl, C
7
or higher aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, acyl, alkyl carboxylate, aryl carboxylate, alkenyl, alkynyl, or E
2
(R
6
)(R
7
)(R
8
);
R
2
is H, halogen, nitro, or haloalkyl;
E
1
and E
2
are independently Si, Ge, Sn, or Pb;
R
3
, R
4
, R
5
, R
6
, R
7
, and R
8
are independently chosen from alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, arylalkyl, alkoxy, alkenyl, alkynyl or R
4
and R
5
, or R
7
and R
8
taken together form a divalent alkyl radical;
Y and Z are independently O, S or NR
9
; and
R
9
is alkyl, substituted alkyl, cycloalkyl, aryl, substituted aryl, heteroaryl, arylalkyl, alkoxy, alkenyl, or alkynyl.
In a preferred embodiment, I is a silyl &bgr;-diketonate or a silyl &bgr;-thioketonate and R
1
is C
2
or higher alkyl, C
7
or higher aryl, or haloalkyl; R
2
is H; R
3
, R
4
, and R
5
are methyl; E
1
is Si; and Y and Z are independently O or S.
In a more preferred embodiment, R
1
is ethyl, isopropyl, n-propyl, isobutyl, n-butyl, t-butyl, trifluoromethyl, heptafluoropropyl, 2-propenyl or phenyl; E
1
is Si; and Y and Z are O or Y
Banger Kulbinder Kumar
Higashiya Seiichiro
Ngo Silvana C.
Welch John T.
Heslin Rothenberg Farley & & Mesiti P.C.
Nazario-Gonzalez Porfirio
Research Foundation of State University of New York
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