High temperature functioning stripper for cured difficult to remove photoresist coatings
A chemical stripping solvent composition is provided for removing cured polymeric isoprene from inorganic substrates comprising normal and isoparaffins exhibiting a high flash point and a sulfonic acid dissolving system. The stripping composition comprises a blend of chemistries, designed to operate at high temperature processing conditions without attack to sensitive metals. The invention will remove fully cured negative-tone isoprene-based photoresist at temperatures equal to or beyond 100° C. Isoprene polymer in the presence of certain cross-linking photoinitiators will cure to a smooth rubber and highly chemically resistant framework. This material is used to produce patterns, which become the basis for depositing microcircuits in semiconductor manufacturing. Upon exposure to the invention, the cured polymer will begin to breakdown, allowing the residue to be rinsed away with IPA or water. A corrosion inhibitor that is proven to be high temperature stable is added to protect metals. Removal rates vary depending upon the thickness of the resist and the condition which it was exposed during the process. Heat and agitation will improve the removal process.
1 . A high temperature stable liquid solvating composition for removing cured cross linked polymeric photoresist surface layers from an inorganic substrate comprising a blend of:
(a) from about 30 to about 55 weight percent of a normal and/or isoparaffins that exhibit boiling fractions in the range between 220-280° C. and a flash point of between 95-120° C.,
(b) about 20 to about 40 weight percent of an iso-paraffin of the formula which exhibits boiling fractions in the range between 220-315° C. and a flash point of between 90-130° C., and
(c) About 20 to about 40 weight percent of an alkylbenzene sulfonic acid.
2 . A liquid solvating composition of claim 1 , which includes also from about 0.5 to about 1.5 weight percent of a corrosion inhibitor.
3 . The composition of claim 1 wherein (a) is present in amounts of about 35 to about 45 weight percent, (b) and (c) are present in amounts of about 25 to about 35 weight percent.
4 . The composition of claim 1 wherein (c) is dodecylbenzene sulfonic acid (DDBSA).
5 . The composition of claim 2 wherein the corrosion inhibitor is 2-mercaptobenzothiazole (MBT).
6 . In a method for removing cured cross-linked polymeric layers from an inorganic substrate the improvement characterized in the materials to be removed is contacted with the stripping solvent of claim 1 at temperatures in excess of 100° C. for a period of time sufficient to remove said substance.
7 . In a method for removing full-cure isoprene negative photoresists from an inorganic substrate the improvement is characterized in that the isoprene resist to be removed is contacted with the stripping solvent of claim 1 at a temperature not less than about 90° C. for a period of time sufficient to remove said substance.
8 . In a method for removing full-cure isoprene negative photoresists from an inorganic substrate the improvement is characterized in that the isoprene resist to be removed is contacted with the stripping solvent of claim 2 at temperatures in the range of from about 100° C. to about 120° C. for a period of time sufficient to remove said substance.
9 . In a method for removing full-cure isoprene negative photoresists from an inorganic substrate the improvement is characterized in that the isoprene resist to be removed is contacted with the stripping solvent of claim 5 at temperatures in the range of from about 100° C. to about 120° C. for a period of time sufficient to remove said substance.