Compositions and methods that promote charge complexing copper protection during low pKa driven polymer stripping
The present invention is a charge complexing chemical composition that protects metal during polymer removal. The polymer coatings include crosslinked systems by chemical-amplification and photoacid generated (PAG) means as in epoxies. The system includes a solvent, a charge complexing additive, and an acid that creates a protective complex for sensitive metals during the dissolving and rinsing practice needed for processing microelectronic parts. The composition can be utilized with a method for removing partial and fully cured crosslinked coatings that originate from chemical amplification or PAG-epoxy photoimageable coatings.
1. A composition that creates a charge complex with metals as a means of protection during a polymer coating removal process, comprising:
a solvent;
an organic acid having a pKa<3; and
an additive exhibiting charge complexing character,
wherein said organic acid is one or more substituted or unsubstituted alkylarylsulfonic acids, and
wherein said additive exhibiting charge complexing character comprises rosin esters.
2. The composition according to claim 1 , wherein said solvent is tetrahydrofurfuryl alcohol (THFA).
3. The composition according to claim 2 , wherein THFA is present at concentrations of >40% w/w.
4. The composition according to claim 1 , wherein the organic acid includes dodecylbenzenesulfonic acid.
5. The composition according to claim 4 , wherein the dodecylbenzenesulfonic acid is present at concentrations of 0.25-1 molar.
6. The composition according to claim 1 , wherein said additive exhibiting charge complexing character further comprises a dicarboxylic acid.
7. The composition according to claim 6 , wherein said dicarboxylic acid is selected from the group consisting of oxalic acid, maleic acid, succinic acid, fumaric acid, phthalic acid, isopthalic acid, and salicylic acid.
8. The composition according to claim 6 , wherein the dicarboxylic acid is present at 0.1-15% w/w.
9. The composition according to claim 1 , wherein the rosin ester exhibits a total acid number (TAN)≥100.
10. The composition according to claim 1 , wherein said additive exhibiting charge complexing character further comprises one or more of fumaric acid, citraconic acid, mesaconic acid, aconitic acid, itaconic acid, maleic acid anhydride, fumarated rosins, maleated rosins, resin modified phenol rosins, tall oil resins, terpene resins, and resin modified acid phenol resins.
11. The composition according to claim 10 , wherein said additive exhibiting charge complexing character is a fumaric modified rosin ester.
12. The composition according to claim 11 , wherein the fumaric modified rosin ester is present at 0.1-15% w/w.
13. A method for removing polymers which cure by chemically amplified or photoacid generated (PAG) means to produce a coating on a substrate, comprising:
applying said composition of claim 1 to said coating utilizing a sprayer, an immersion bath or chamber;
exposing said composition directly on said coating for a predetermined period of time at a predetermined temperature; and
rinsing and drying said exposed substrate.
14. The method according to claim 13 , wherein said period of time is less than 30 minutes.
15. The method according to claim 13 , wherein said temperature is 20° C. to 100° C.
16. The method according to claim 13 , wherein said coatings are utilized in microelectronics fabrication and semiconductor production.