Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Reexamination Certificate
2000-07-31
2002-11-05
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
C156S001000, C252S182280, C252S182280, C430S256000
Reexamination Certificate
active
06475292
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to the field of photoresist removers. In particular, the present invention relates to compositions useful for the removal of photoresists and probing inks from an electronic device substrate.
In the manufacture of semiconductor microcircuits it is necessary to mark defective microchips during the final electrical testing with an epoxy or polyurethane based ink on the finished silicon wafer to distinguish bad dies from the good dies. After the electrical test is done, sometimes it may be deemed necessary to clean the ink off the silicon wafer because of a wrong electrical test program, because bonding pads were misprobed, or for other rework reasons. This allows the silicon wafer to be retested or reprobed with the necessary corrections. Conventional solvents such as alcohols, ketones and esters, or more aggressive heterocyclic or commonly used aprotic polar solvents such as N-methyl pyrrolidone, dimethyl acetamide or dimethyl sulfoxide do not remove hard baked and cured epoxy type probing ink even at elevated temperatures and long process times.
Highly acidic or alkaline solutions and strong oxidizing agents on the other hand, such as fuming nitric acid, sulfuric acid/hydrogen peroxide, and tetramethyl ammonium hydroxide or other alkaline solutions may be effective in removing the ink, but they create corrosion difficulties and stain or destroy the sensitive alloys, such as Al/Cu/Si, in bonding pad areas of the wafer.
Negative-type photoresists are used for lithographically delineating patterns onto a substrate so that the patterns can be subsequently etched or otherwise defined into the substrate material. The resist material is deposited as a film and the desired pattern is defined by exposing the resist film to energetic radiation. Thereafter the unexposed regions are subject to a dissolution by a suitable developer liquid. After the pattern has been thus defined in the substrate the resist material must be completely removed from the substrate to avoid adversely affecting or hindering subsequent operations or processing steps.
It is necessary in such a photolithographic process that the photoresist material, following pattern delineation, be evenly and completely removed from all exposed areas so as to permit further lithographic operations. Even the partial remains of a resist in an area to be further patterned is undesirable. Also, undesired resist residues between patterned lines can have deleterious effects on subsequent processes, such as metallization, or cause undesirable surface states and charges.
For example, U.S. Pat. No. 4,992,108 (Ward et al.) discloses a negative photoresist stripping composition consisting essentially of about 60 to 96% wt of diiopropylbenzene and about 4 to 40% wt of an organic sulfonic acid. U.S. Pat. No. 4,165,294 (Mey) discloses a photoresist stripping composition including about 5 to 60% wt of a surfactant alkylarylsulfonic acid having 12-20 carbons; about 15 to 95% wt. of a hydrotropic aromatic sulfonic acid having 6-9 carbons; and from about 0 to 40% wt. of a halogen-free aromatic hydrocarbon solvent with a boiling point above 150° C. Such compositions disclosed in these patents show some corrosion of sensitive metal parts.
PCT patent application WO 00/33140 (Sahbari) discloses a composition for removing probing ink or photoresist including from about 25 to about 85% wt. anisole and from about 15 to about 60% wt. of an alkylarylsulfonic acid having 12 to 20 carbons. While such compositions do not show corrosion of sensitive metal parts, such compositions suffer from volatility of the components and shortened bath life.
It is therefore highly desirable to provide an environmentally safe stripping composition that in a reasonably short process time cleans only the cured probing ink or photoresist without leaving any residue, and that is also safe to use on sensitive metal layers. It is further desirable to provide a stripping composition having decreased volatility and increased bath life.
SUMMARY OF THE INVENTION
It has been surprisingly found that the compositions of the present invention are effective at removing photoresists and probing inks from electronic device substrates, such as silicon wafers, without causing corrosion of the substrates. Such compositions are also lower in toxicity and are more non-hazardous to the user and the environment than known compositions. The compositions of the present invention also remove such photoresists and probing inks more quickly than conventional strippers. It has also been surprisingly found that such compositions are effective as debonding agents for removing wafer bonding adhesives.
In one aspect, the present invention provides a composition including one or more (C
6
-C
16
)olefins, one or more (C
1
-C
6
)alkoxybenzenes, and one or more organic sulfonic acid compounds.
In a second aspect, the present invention provides a method for removing material selected from photoresist, probing ink or wafer bonding adhesive from a substrate including the step of contacting the material with the composition described above.
In a third aspect, the present invention provides a method for manufacturing electronic devices including the steps of disposing a photoresist on a substrate to form a photoresist layer, exposing the photoresist layer through a photomask to a source of activating radiation, developing the photoresist layer to produce a pattern, etching the photoresist to transfer the pattern to the substrate, and removing the photoresist layer, wherein the photoresist layer is removed by contacting the photoresist with the composition described above.
DETAILED DESCRIPTION OF THE INVENTION
An object of this invention is to provide compositions for probing ink, photoresist and wafer bonding adhesive removal. Such compositions are not corrosive to sensitive alloys and do not adversely effect the sensitive bonding pad areas of a semiconductor wafer.
As used throughout this specification, the following abbreviations shall have the following meanings unless the context clearly indicates otherwise: PVA=poly(vinyl acetate); % wt.=percent by weight; mL=milliliter; ° C.=degrees Centigrade; min.=minutes; and sec.=seconds. All percents are by weight. All numerical ranges are inclusive.
The terms “stripping” and “removing” are used interchangeably throughout this specification. Likewise, the terms “stripper” and “remover” are used interchangeably. “Alkyl” and “alkoxy” refer to linear, branched and cyclic alkyl and alkoxy, respectively.
The compositions of the present invention include one or more (C
6
-C
16
)olefins, one or more (C
1
-C
6
)alkoxybenzenes, and one or more organic sulfonic acid compounds. The (C
6
-C
16
)olefins useful in the present invention may have at least one one olefinic bond. By “olefinic bond” is meant a carbon-carbon double bond. Suitable (C
6
-C
16
)olefins include, but are not limited to, (C
6
-C
16
)olefins having one carbon-carbon double bond, (C
6
-C
16
)dienes, (C
6
-C
16
)trienes, and the like. Particularly suitable (C
6
-C
16
)olefins include alpha-olefins. “Alpha-olefins” are olefins having a carbon-carbon double bond between the first and second carbon of the carbon chain, but may have additional olefinic bonds in the carbon chain. Preferred alpha-olefins include (C
8
-C
16
)olefins, and more preferably 1-decene and 1-dodecene. Mixtures of olefins are particularly suitable for use in the present invention and mixtures of alpha-olefins are preferred. Such olefins are generally commercially available from a variety of sources and may be used without further purification. The amount of (C
6
-C
16
)olefins present in the compositions of the invention is typically in the range of from about 10 to about 55% wt, based on the total weight of the composition, and preferably from about 20 to about 40% wt.
Any (C
1
-C
6
)alkoxybenzene may be used in the present invention. Such (C
1
-C
6
)alkoxybenzenes may be substituted. By “substituted (C
1
-C
6
)alkoxybenzenes” is meant that one o
Cairns S. Matthew
Gulakowski Randy
Shipley Company L.L.C.
Winter Gentle E.
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