Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Finishing or perfecting composition or product
Reexamination Certificate
2001-02-26
2003-12-30
Dunn, Tom (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Finishing or perfecting composition or product
C430S311000, C430S329000, C510S175000
Reexamination Certificate
active
06670107
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of manufacture of electronic devices. In particular, the present invention relates to compositions and methods for the reduction of defects during the manufacture of electronic devices.
Photoresists are photosensitive films used for transfer of images to a substrate. A coating layer of a photoresist is formed on a substrate and the photoresist layer is then exposed through a photomask to a source of activating radiation. The photomask has areas that are opaque to activating radiation and other areas that are transparent to activating radiation. Exposure to activating radiation provides a photoinduced chemical transformation of the photoresist coating to thereby transfer the pattern of the photomask to the photoresist-coated substrate. Following exposure, the photoresist is developed to provide a relief image that permits selective processing of a substrate.
A photoresist can be either positive-acting or negative-acting. For most negative-acting photoresists, those coating layer portions that are exposed to activating radiation polymerize or crosslink in a reaction between a photoactive compound and polymerizable agents of the photoresist composition. Consequently, the exposed coating portions are rendered less soluble in a developer solution than unexposed portions. For positive-acting photoresists, exposed portions are rendered more soluble in a developer solution while areas not exposed remain comparatively less developer soluble. In general, photoresist compositions include at least a resin binder component and a photoactive agent.
Following exposure, the film layer of the photoresist composition is preferably baked at temperatures ranging from about 70° C. to 160° C. Thereafter, the film is developed. The exposed resist film is rendered positive working by employing a polar developer, typically an aqueous based developer, such as quaternary ammonium hydroxide solutions, such as tetra-alkyl ammonium hydroxide, preferably a 0.26 N tetramethylammonium hydroxide; various amine solutions, such as ethylamine, n-propylamine, diethylamine, triethylamine or methyl diethylamine; alcohol amines, such as diethanolamine, triethanolamine; cyclic amines, such as pyrrole, pyridine, and the like.
After development of the photoresist coating, the developed substrate may be selectively processed on those areas bared of resist, for example, by chemically etching or plating substrate areas bared of resist in accordance with procedures known in the art. For the manufacture of microelectronic substrates, e.g. the manufacture of silicon dioxide wafers, suitable etchants are a gas etchant, such as a chlorine- or fluorine-based etchant, such as Cl
2
or CF
4
/CHF
3
etchant applied as a plasma stream. After such processing, the resist may be removed from the processed substrate using any stripping procedures known in the art.
Following contact of the photoresist with developer or stripper, the electronic device, e.g. a wafer, is then rinsed, typically first with iso-propanol and then with deionized water. Such rinses are used to remove any remaining developer or stripper solution and to help remove any remaining photoresist particles or residue. Even after such development, stripping and rinsing, the electronic device may contain on its surface residual photoresist, either in the form of polymer, particulates or residue. Such residual photoresist can cause defects, such as shorts, in the resulting electronic device.
There is thus a need for an effective method for reducing the number of defects in electronic devices, particularly those due to residual photoresist or photoresist residue remaining after development or stripping of the photoresist.
SUMMARY OF THE INVENTION
It has been surprisingly found that the number of defects in electronic devices can be significantly reduced according to the present invention. Yield losses due to defects are also improved by the compositions and methods of the present invention.
In one aspect, the present invention provides a method for reducing the number of defects in an electronic device including the step of contacting the electronic device with a composition including one or more surfactants and water, wherein the amount of surfactant in the composition is less than the critical micelle concentration.
In a second aspect, the present invention provides a method of manufacturing an electronic device including the steps of at least partially removing a photoresist layer from a substrate; and contacting the substrate having the partially removed photoresist with a composition including one or more surfactants and water, wherein the amount of surfactant in the composition is less than the critical micelle concentration.
In a third aspect, the present invention provides an electronic device prepared according to the method described above.
In a fourth aspect, the present invention provides a method of removing photoresist including the steps of contacting a photoresist layer on a substrate with a composition including one or more surfactants and water wherein the amount of surfactant in the composition is less than the critical micelle concentration; and at least partially removing the photoresist layer.
DETAILED DESCRIPTION OF THE INVENTION
As used throughout this specification, the following abbreviations shall have the following meanings unless the context clearly indicates otherwise: DI=deionized; ppm=parts per million; % wt=percent by weight; and RPM=revolutions per minute. All percents are by weight and all numerical ranges are inclusive.
The compositions of the present invention are suitable for reducing defects in an electronic device by removing polymeric residue from the surface of such device. In particular, the compositions of the present invention are particularly suitable for reducing defects in an electronic device by removing photoresist residue from the surface of such device. While not intending to be bound by theory, it is believed that the compositions of the present invention function to help solubilize, disperse, chelate, entrain, encapsulate or otherwise remove polymer residue, particularly polymer particulates, from the surface of the substrates so treated. The present invention may be used in the manufacture of any electronic devices, such as, but not limited to, wafers, circuit boards, and the like.
The compositions of the present invention include one or more surfactants and water, wherein the amount of the surfactant in the composition is less than the critical micelle concentration. While any grade of water is suitable for use in the present invention, deionized water is preferred.
The particular surfactant used in the present invention is not critical. Thus, any surfactant is suitable for use in the present invention. Thus, anionic, cationic, nonionic and amphoteric surfactants may be advantageously used in the present invention. It is preferred that the surfactant is cationic or nonionic, and more preferably nonionic. Particularly suitable nonionic surfactants are ethylene oxide/propylene oxide (“EO/PO”) copolymers. It will be appreciated by those skilled in the art that mixtures of surfactants may be suitably used in the present invention. Thus, mixtures of cationic and nonionic surfactants and mixtures of anionic and nonionic surfactants may be used in the present invention. Such surfactants are generally commercially available from a variety of sources and may be used without further purification. Such surfactants may be available as an aqueous composition, which may be used in the present invention.
Any amount of surfactant is suitable for use in the present invention as long as it is less than the critical micelle concentration (“CMC”). “Critical micelle concentration” refers to the concentration of surfactant in water above which the surface tension remains substantially invariant with increasing surfactant concentration. Such critical micelle concentration is well known to those skilled in the art. Typically, the amoun
Cairns S. Matthew
Dunn Tom
Shipley Company L.L.C.
Walke Amanda C.
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