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Process for Physical Vapor Deposition of Polyamic Acid Films

IP.com Disclosure Number: IPCOM000060723D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Duran, J: AUTHOR [+4]

Abstract

Polyimide films are widely used in microelectronics and magnetic technology, and are produced from polyamic acid precursors. These methods for making polyimide films include either dipping, spraying, or spin casting polyamic acid suspended as a dilute polymer solution in an organic solvent, or the single source evaporation of a mixture of pyromellitic dianhydride and 4, 4'-diamino-diphenyl ether or dried polyamic acid powder. However, these techniques do not assure stoichiometric control of the precursor flow in an exacting appropriate ratio, irrespective of individual precursor vapor pressure. An improved method is described which is solventless and uses source materials with essentially infinite shelf life, once purified. High temperature polyamic acid films are vapor deposited upon a multitude of substrate surfaces.

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Process for Physical Vapor Deposition of Polyamic Acid Films

Polyimide films are widely used in microelectronics and magnetic technology, and are produced from polyamic acid precursors. These methods for making polyimide films include either dipping, spraying, or spin casting polyamic acid suspended as a dilute polymer solution in an organic solvent, or the single source evaporation of a mixture of pyromellitic dianhydride and 4, 4'-diamino- diphenyl ether or dried polyamic acid powder. However, these techniques do not assure stoichiometric control of the precursor flow in an exacting appropriate ratio, irrespective of individual precursor vapor pressure. An improved method is described which is solventless and uses source materials with essentially infinite shelf life, once purified. High temperature polyamic acid films are vapor deposited upon a multitude of substrate surfaces. The deposition system 10 consists of vacuum chamber 12, pumped to a pressure of approximately 10-6 Torr, containing two evaporant source ovens 14A, 14B. One oven is for the dianhydride, and the other is for the diamine monomers. A baffled mixing oven 16 is also provided. The effusion rate of each oven is controlled by a servo-loop consisting of a rate/thickness sensor 18, rate controller circuit including evaporant sensing heads 19A, 19B, heater power supply 20, and an evaporant heater (oven). The individual vapor streams are combined within mixing oven 16, which is held at atemperature slightly above that of either source oven 14A, 14B. The purpose of baffled mixing oven 16 is to produce a single homogeneous vapor stream and to free the vapor of particulate matter. The combined vapor stream is homogeneous and obeys the laws of physical vapor deposition. When shutter 21 is rotated out of the way, the co...