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US 5,688,893 AGranted
Method of using a Lewis base to control molecular weight of novolak resins
AssigneeHoechst Celanese Corporation
InventorsM. Dalil Rahman, Daniel P. Aubin, Dana L. Durham, Ralph R. Dammel
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Abstract
The present invention provides methods for producing water insoluble, aqueous alkali soluble novolak resins having a precise and consistent molecular weight, by adjusting the concentration of Lewis base. A method is also provided for producing photoresist composition from such novolak resins and for producing semiconductor devices using such photoresist compositions.
Claims5
A method for producing a water insoluble, aqueous alkali soluble novolak resin comprising:
- a) providing an admixture of formaldehyde, one or more phenolic compounds and a catalytic amount of a acidic catalyst;
- b) Lewis base concentration before condensation providing such admixture with a of from about 10 to 1000 ppm;
- c) condensing the formaldehyde with the one or more phenolic compounds, in presence of the catalyst, and thereby producing a water insoluble, aqueous alkali soluble novolak resin having a substantially consistent molecular weight.
Dependencies are inferred from the claim text.