Siloxane Modified Polyimides for Microelectronics Coating Applications

Abstract

Two types of siloxane modified polyimide were prepared as coating materials for microelectronics applications and their thermal, mechanical, electrical, adhesive and coating properties were characterized. The coatings prepared were classified as polysiloxane block (type A) polyimides and disiloxane modified (type B) polyimides. All of the polyimides showed excellent thermal, mechanical, electrical, adhesive and coating properties suitable for use in microelectronics coating applications. The type A polyimides have lower dielectric constants and good stress relaxation capability as compared with typical aromatic polyimides. The type B polyimides have excellent adhesive properties to silicon wafers. The polyimide prepared from 2, 2-bis[4-aminophenoxyphenyl]hexafluoropropane exhibited the lowest dielectric constant due to the presence of trifluoromethyl groups in the polymer backbone. Model encapsulated semiconductor devices coated with various polyimides were assembled, and the interface adherence between the polyimide and the encapsulant along with the reliability of the semiconductor devices were examined. Superior interface adherence between the polyimide passivant and the encapsulant was exhibited, resulting in improved reliability of integrated circuit chips. With the incorporation of siloxane moieties into the polyimide backbone these siloxane modified polyimides were shown to be good candidate materials for microelectronics coatings.