Polyimides in microelectronics

PFMB can be used to prepare aromatic polyimides that display solubility in ketone, ether, and polar aprotic solvents. This unusual solubility can be utilized in die facile preparation of thin films that display anisotropy in their structures and properties. The anisotropy in the optical properties of the films makes them promising candidates for use as compensation layers in liquid-crystal displays. Their low dielectric constants and CTEs in combination with their outstanding thennal and thermooxidative stabilities make diem candidates for dielectric layers in microelectronics applications. 

EP 0518060 (European) 1992 Polyimide-si-loxane extended block copolymers Occidental Chemical S Rojstaczer Useful as coatings and adhesives in microelectronic have higher Tg than the corresponding non-ext ended block copolymers while retaining solubility Siloxane-imide block copolymers were prepared using amino-terminated siloxanes and organic diamines along with pref. aromatic dianhydrides... 

Polyimides are Hnding increased use in microelectronics [1-6]. There are four primary areas of application 1) as fabrication aids 2) as passivants and interlevel insulators 3) as adhesives and 4) as components of the substrate or circuit board. In each plication, the requirements on properties and performance differ. This paper addresses primarily the first two applications. 

Polyimides for microelectronics use are of two basic types. The most commonly used commercial materials (for example, from Dupont and Hitachi) are condensation polyimides, formed from imidization of a spin-cast film of soluble polyamic acid precursor to create an intractable solid film. Fully imidized thermoplastic polyimides are also available for use as adhesives (for example, the LARC-TPI material), and when thermally or photo-crosslink able, also as passivants and interlevel insulators, and as matrix resins for fiber-reinforced-composites, such as in circuit boards. Flexible circuits are made from Kapton polyimide film laminated with copper. The diversity of materials is very large readers seeking additional information are referred to the cited review articles [1-3,6] and to the proceedings of the two International Conferences on Polyimides [4,5]. 

Of great ultimate interest in the application of polyimides to microelectronics is a fundamental understanding of structure-property relations, that is, an understanding of how to relate critical performance properties to det s of composition and structure. As new experimentas becomes better documented, and as insights into how to achieve reproducible measurements are obtained, the prospect of achieving that goal improve. 

Wholly aromatic polyimides are highly thermally stable engineering plastics, and have been widely used as the reliable insulating materials in microelectronics. Recent developments in this field toward higher integration of devices required ultra thin films of polyimides. Minimum thickness of polyimide films cast by spin coating was about 0.1 Urn. 

To our knowledge, the present polyimide monolayer films possess the minimum thickness ever produced. We believe that this simple and efficient method for the preparation of polyimide mono- and multilayer films will bring about new technology especially in microelectronics. 

Thermal tempering of the photosensitive or cross-linked polymer gives the polyimide siloxane which has been previously shown to be an excellent candidate as an insulating polymer in electronics. The use of such a directly patternable polyimide for dielectric and passivation applications, particularly in microelectronics, should become increasingly important as polyimides become more widely accepted in the industry. 

In industry, polyimides are widely used as dielectric in microelectronics for multichip modules [85,86] and printed circuit boards [87], as substrate for inkjet... 

The polymers considered for these applications are primarily polyimides. Although polyimides have been used as electrical insulation for the past 15 years, and a considerable know-how has been generated about these polymers and their applications as insulation, their use in microelectronic devices provides new challenges. Because the interlayers are approximately 2um thick. 

Metallized high-temperature polymers such as polyimides are nowadays widely used in microelectronics and other fields. At elcvaied lemperatures, usually encountered during processing, diffusion of the metal not only at the polymer surface but also into the bulk of the polymer may play an important role in d nnining interface formation and structure as well as the dielectric properties of the polymer after metallization . 

Polyifflides are commonly utilized as dielectric layers in the fabrication of microelectronic devices. Hence the metallization of polyimldes and the chemical and physical nature of metal-polyimide interfacea is of great technical importance and has been investigated extensively. Polyimldas perform well In microelectronic... 

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