Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2001-11-08
2003-12-09
Nazario-Gonzalez, Porfirio (Department: 1621)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C148S403000, C148S903000, C427S533000, C427S595000, C427S597000, C428S615000, C428S674000, C556S113000
Reexamination Certificate
active
06660632
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of metal complexes to deposit films of metals or metal oxides. Such films may be of use in a variety of applications, including but not limited to microelectronics fabrication.
BACKGROUND OF THE INVENTION
Deposition of thin films using non-vacuum techniques normally comprises either sol gel or metal organic materials or comprises photochemical metal organic depositions. Films of inorganic materials are usually deposited by chemical or physical vapor deposition, although in some cases, sol gel or metal organic deposition has been used. The sol gel or metal organic depositions require the construction of films of precursors. These films are then heated to drive off the organic component, leaving a metal or more commonly, a metal oxide film. The photochemical deposition method differs from the above two methods in that the reaction which drives off the organic component is photochemically activated. Since none of these methods are able to form the patterned structures normally used in the construction of microelectronic devices or circuits, they must be employed with other processes in order to pattern films of materials.
Hybrid methods often use light as the energy source wherein the light used initiates a thermal rather than a photochemical reaction. These methods have the disadvantage that they do not directly result in the formation of patterned films but result in the unselective deposition of the films.
Additional disadvantages of the previously described deposition methods are that they require the use of expensive equipment and many of them require high temperature processing.
Because of the problems associated with possible contamination of clean room facilities, a single chemical which may be used for different deposition methods is desirable. Furthermore, the use of a single chemical for different deposition methods reduces the product development expense to the supplier.
Metals, such as copper, may be used as a conductor in electronic circuits. Other metal oxides, such as copper oxide, are semiconductors and have found use as a conductor in electronic circuitry. Accordingly there is much interest in developing methods of achieving the deposition of metals and the patterned deposition of metals or their oxides on various substrates.
U.S. Pat. No. 5,534,312 to Hill et al., incorporated herein by reference, describes a method for the deposition of a variety of metal and metal oxide systems using photochemical deposition. It will be appreciated that the approach discussed therein is a substantial improvement in the prior art. The current invention presents new types of metal complexes or precursors which are useful for thermal, electron beam, and photochemical patterning of copper containing materials and a method for depositing these complexes.
Prior art precursors used to deposit metal or metal oxide films, such as that shown below, and disclosed in U.S. Pat. No. 5,534,312, are known to fragment under photolytic conditions, leading to the loss of CO
2
. This fragmentation leaves the metal atoms unbound.
Complexes disclosed by Chung et al. in J. Chem. Soc., Dalton Trans., 1997, p. 2825-29, which is incorporated herein by reference, also comprise a pair of metal atoms bonded to bidentate organic ligands. The most general form of these complexes has the following formula.
In the above formula, the individual sites where substitution may be used to optimize the physical and chemical properties are shown. The organic ligand framework of these complexes shows no obvious site for fragmentation under, for example, photolytic conditions. Therefore, it is not clear that complexes of this formula should be suitable for photolytic deposition of metals or metal oxides. In fact it could reasonably be predicted that the photochemical reactivity should center about the groups X
1
and X
2
in the figure. Indeed, the published photochemistry for this complex (Chung et al., (1997) J. Chem. Soc. Dalton Trans., 2825) leads one of skill in the art to expect that photochemistry should yield a stable Cu(I) complex. Based on the prior art, one would not expect it to be possible to use these new precursors to deposit metal or metal oxide films at all. In an amorphous film comprising such a complex, however this is not the case and Cu metal is formed, a highly unexpected result.
It is therefore surprising that new precursors of the form shown above have been found that are useful in depositing films composed of a metal, such as copper, or its oxides. These new precursors exhibit an unexpected fragmentation site to yield the desired metal or metal oxide film. Preliminary mass spectral evidence suggests that the ligand in fact degrades during the photoreaction, a result that was not readily predicted.
SUMMARY OF THE INVENTION
The present invention is directed to a photoresist-free method for depositing films composed of a metal, such as copper, or its oxides from metal complexes. More specifically, the method involves applying an amorphous film of a metal complex to a substrate. The complexes of the present invention are generally of the formula, M
f
L
g
X
h
, wherein M is selected from the group consisting of Ti, V, Cr, Au, Mn, Fe, Co, Ni, Cu, Zn, Si, Sn, Li, Na, K, Ba, Sr, Mo, Ru, Pd, Pt, Re, Ir, and Os; L is a ligand of the formula (R
2
NCR′
2
CR″
2
O), wherein R, R′ and R″ are independently selected from H, C
n
H
m
, and C
n
H
m
A
x
B
y
, wherein A and B are independently selected from main group elements and f, g, h, n, m, x and y represent integers; and X is an anion independently selected from N
3
, NCO, NO
3
, NO
2
, Cl, Br, I, CN, OH, H, and CH
3
. In a preferred embodiment, the metal is dinuclear copper, the ligand is 1-diethylaminoethan-2-ol, and the anion is selected from N
3
, NCO, and NO
2
.
These films, upon either thermal, photochemical or electron beam stimulus may be converted to a metal or its oxides. By using either directed light or electron beams, this may lead to a patterned metal or metal oxide film in a single step. The metal (e.g., copper) or its oxide (e.g., copper oxide) deposited by this method is conductive. Accordingly, these metal precursors and the deposition of the metals or their oxides from such precursors is a useful invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The current invention describes the use of complexes of metals such as copper, to form films which may be activated by thermolysis, charged particles (such as electron beams), or photons to deposit copper containing films.
An amorphous precursor film comprising the complex is deposited onto a substrate using methods well known in the art, such as spin or dip deposition. This film is then exposed to electromagnetic radiation or electron or ion beams. This exposure results in the conversion of the exposed areas from the precursor material to the desired amorphous film of the metallic material. The precursor complexes of the present invention are generally of the formula, M
f
L
g
X
h
, wherein M is selected from the group consisting of Ti, V, Cr, Au, Mn, Fe, Co, Ni, Cu, Zn, Si, Sn, Li, Na, K, Ba, Sr, Mo, Ru, Pd, Pt, Re, Ir, and Os; L is a ligand of the formula (R
2
NCR′
2
CR″
20
), wherein R, R′ and R′ are independently selected from H, C
n
H
m
, and C
n
H
m
A
x
B
y
, wherein A and B are independently selected from main group elements and f, g, h, n, m, x and y represent integers; and X is an anion independently selected from N
3
, NCO, NO
3
, NO
2
, Cl, Br, I, CN, OH, H, and CH
3
.
An example of such precursor complexes include dinuclear copper complexes with suitable bidentate ligands. Suitable ligands include: &mgr;-aminopropan-2-olate, diethylaminoethan-2-olate, diethylaminobutan-2-olate, and the like. Related complexes are disclosed by Chung et al. in J. Chem. Soc., Dalton Trans., 1997, p. 2825-29. Such dinuclear copper precursor complexes are generally of the formula Cu
2
(R
2
NCR′
2
CR″
2
O)
2
X
2
, wherein R, R′ and R″ are independently selected from H,
Hill Ross H.
Shi Yo Mao
EKC Technology, Inc.
Nazario-Gonzalez Porfirio
Pennie & Edmonds LLP
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