Title :
Processing thick multilevel polyimide films for 3-D stacked memory
Author :
Caterer, Michael D. ; Daubenspeck, Timothy H. ; Ference, Thomas G. ; Holmes, Steven J. ; Quinn, Robert M.
Author_Institution :
IBM Microelectron. Div., Essex Junction, VT, USA
fDate :
5/1/1999 12:00:00 AM
Abstract :
This paper discusses thick polyimide film processing for a three-dimensional (3-D) semiconductor chip-stacking application. The formation of a complex, multilevel via structure is demonstrated. The issues that arise in forming these vias relate to apply, develop, profile modification, and integration. Apply issues include “outgassing” defects, edge-bead effects, as well as the planarity and leveling of both resist and polyimide over deep-via structures. Develop issues pertain to the implementation of a thick resist process that increases the structural integrity of the resist and controls its breakage, and to a vacuum bake before applying resist, which reduces solvent absorption into the resist. Profile modification issues include rounding via edges while minimizing bulk polyimide loss and maintaining image-size control. Developer attack of the metal pads during wet processing is discussed and a solution is proposed. Finally, additional process-integration issues relating to polyimide-to-metal adhesion and composite stress levels of the multilayer thick films are presented
Keywords :
adhesion; integrated circuit interconnections; integrated memory circuits; photoresists; polymer films; thick films; 3D stacked memory; composite stress; edge-bead effect; interconnect; multilevel via; outgassing defect; photoresist; planarization; polyimide multilayer thick film; polyimide-to-metal adhesion; process integration; three-dimensional semiconductor chip; vacuum bake; wet processing; Absorption; Adhesives; Nonhomogeneous media; Polyimides; Resists; Semiconductor films; Solvents; Stress; Thick films; Thickness control;
Journal_Title :
Advanced Packaging, IEEE Transactions on
DOI :
10.1109/6040.763191