Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2003-04-30
2004-08-10
Gurley, Lynne (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S669000, C438S674000, C438S681000, C438S686000, C438S687000
Reexamination Certificate
active
06774034
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims the benefit of the Korea Application No. 2002-23754 filed on Apr. 30, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an organometallic precursor for forming a metal pattern and a method of forming a metal pattern using the same. More particularly, the present invention relates to an organometallic precursor for forming a micro- or a nano-sized conductive metal pattern using light and without using a photosensitive resin and a method of forming such a metal pattern using the same.
2. Description of the Prior Art
As is well known to those skilled in the art, a patterned thin film formed on a substrate using materials having different electrical properties has been applied to various electronic devices. In an electronic device production process, a metal thin film is generally coated on a substrate such as a crystallized silicon wafer and then patterned.
A conventional method of forming a metal pattern comprises the steps of depositing an organometallic compound on a silicon or glass substrate using a chemical vapor deposition process or an atomic layer deposition process to form a thin film on the substrate; coating a photoresist on the resulting substrate according to a spin coating process; patterning the photoresist film according to a photolithography process; and etching the organometallic film through the patterned photoresist film. Another conventional method of forming a metal pattern comprises the steps of forming a metal film on a substrate according to a plasma deposition process, a sputtering process, or an electric plating process; coating a photosensitive resin on the resulting substrate; patterning the coated substrate using light; and etching the patterned substrate to form a desired metal pattern. These conventional methods require a high temperature and vacuum devices, and a patterning step using the photosensitive resin and an etching step for removing the photosensitive resin, thus having the disadvantage of a high production cost due to a complicated process. Other disadvantages of these conventional methods are that the resolution of the resulting pattern is inevitably reduced because the patterning and etching steps are typically repeated several times, and that the surface of a deposited metal film is not smooth, causing these conventional methods to additionally require a flatting step.
Meanwhile, various methods of forming a metal pattern without using a photoreaction have been suggested. For example, Japanese Patent Publication No. 62-263973 discloses a method of forming a metal pattern, in which an electronic beam is irradiated on a thin film of an organometallic compound without inducing any photoreaction. In addition, U.S. Pat. No. 5,064,685 discloses a method of forming a thin metal film using a thermal decomposition reaction, comprising the steps of coating an organometallic compound-containing ink on a substrate; and heating the resulting substrate with the use of a laser beam. According to this patent, the substrate is exposed to a high temperature, and materials other than metals are prevented from being deposited on the substrate.
Another example of a method of forming a metal pattern is proposed by U.S. Pat. No. 5,534,312, in which organic compounds sensitive to light are coordinate-bonded to a metal to produce an organometallic compound, the organometallic compound thus produced is coated on a substrate, and the resulting substrate is irradiated by the light to form a metal pattern without a coating step using a photosensitive resin. The organometallic compound according to this patent necessarily includes at least one ligand selected from the group consisting of acetylacetonates, dialkyldithiocarbamates, carboxylates, pyridines, amines, diamines, arsines, diarsines, phosphines, diphosphines, arenes, alkoxy ligands, alkyl ligands, and aryl ligands. Particularly, when the organometallic compound includes two or more ligands, at least one ligand is selected from the group consisting of oxalato, halogen, hydrogen, hydroxy, cyano, carbonyl, nitro, nitrito, nitrate, nitrosyl, ethylene, acetylene, thiocyanato, isothiocyanato, aquo, azide, carbonato, amine, and thiocarbonyl. According to this patent, when the organometallic compound is coated on the substrate and exposed through a patterned mask, the light is directly reacted with the organometallic compound to decompose organic ligands coordinate-bonded to the metal to separate the organic ligands from the metal and to react the metal with surrounding metal atoms and/or oxygen in the atmosphere to form a metal or a metal oxide film pattern. However, this patent is disadvantageous in that the organometallic compound as described above is slowly decomposed by exposure to light, and so the pattern forming rate is slow. Other disadvantages are that a ligand contamination is caused because most ligands are separated from the metal by a photoreaction to form the metal or metal oxide film, and the oxide film thus formed is reduced and annealed under a mixed gas of hydrogen with nitrogen at 200° C. or higher for 30 minutes to several hours so as to improve conductivity of the oxide film.
In addition, there remains an urgent need to develop a metal compound capable of readily forming a metal pattern and meeting an increasing demand for fineness and low specific resistance of metal wiring in the modern semiconductor industry.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made, keeping in mind the above disadvantages occurring in the prior art, and an object of the present invention is to provide an organometallic precursor for precisely forming a conductive metal pattern, in which ligands are readily separated by light from metals so as to reduce the time for forming the metal pattern.
It is another object of the present invention to provide a method of forming a metal pattern using such an organometallic precursor.
It is still another object of the present invention to provide an organometallic precursor mixture of the above organometallic precursor with another organometallic precursor.
It is yet another object of the present invention to provide a method of forming a metal pattern using such an organometallic precursor mixture.
According to a first aspect of the present invention, an organometallic precursor is provided for forming a metal pattern defined by the following Formula (I):
M
m
L
n
L′
o
X
p
(I)
wherein,
M is a transition metal selected from the group consisting of Ag, Au, and Cu;
L is a neutral ligand selected from the group consisting of amines, phosphines, phosphites(P(OR)
3
), phosphine oxides, arsines, and thiols;
L′ is a negatively charged ligand selected from the group consisting of &bgr;-diketonates, &bgr;-ketoiminates, &bgr;-diiminates, carboxylates, and dialkyldithiocarbamates;
X is an anion selected from the group consisting of halogeno, hydroxide (OH
−
), cyanide (CN
−
), nitrite (NO
2
−
), nitrate (NO
3
−
), nitroxyl (NO
−
), azide (N
3
−
), thiocyanato, isothiocyanato, tetralkylborate, tetrahaloborate, hexafluorophosphate (PF
6
−
), triflate (CF
3
SO
3
−
), tosylate (Ts
−
), sulfate (SO
4
2−
), and carbonate (CO
3
2−
);
m is an integer ranging from 1 to 10;
n is an integer ranging from 1 to 40;
o is an integer ranging from 0 to 10; and
p is an integer ranging from 0 to 10.
According to a second aspect of the present invention, a method is provided for forming a metal pattern, comprising the steps of dissolving the organometallic precursor in an organic solvent to provide a coating solution; applying the coating solution on a substrate to form a thin film on the substrate; exposing the thin film with the use of a photomask; and developing the exposed thin film to form a metal or metal oxide pattern on the substrate.
According to a third aspect of the present invention, an organometallic precursor mixture is provided for forming a metal pattern, produced by m
Byun Young Hun
Hwang Euk Che
Hwang Soon Taik
Birch & Stewart Kolasch & Birch, LLP
Gurley Lynne
Samsung Electronics Co. LTD
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