Polyimides interconnections

Figure 20. Multichip test vehicle for submicrometer bipolar ICs. The vehicle contains Jive metal layers of copper-polyimide interconnections on a pinned cofired ceramic substrate (3 by 3 in. [7,6 by 7.6 cm]) (Reproduced with permission from reference 79. Copyright 1988 Materials Research Society.)...

Figure 21. Nine-chip microprocessor module with TFML copper-polyimide interconnections on an 80 by 80 mm ceramic substrate. Top, completed package populated with tape-automated-bonded lCs bottom, internal signal interconnection layers. (Reproduced from reference 80. Copyright 1987 American...

Figure 23. Multichip package for a supercomputer. Top, unpopulated substrate with TFML copper-polyimide interconnections on a 100 by 100 mm multilayer ceramic substrate bottom, cross section of interconnection structure and flip-TAB carrier. (Reproduced with permission from reference 81. Copyright 1985 Institute of Electrical and Electronics Engineers.)...

Figure 1. Proposed approach for multichip packaging using thin film multilayer Cu/polyimide interconnections.

Figure 5.5 Examples of multichip modules in which die-attachment adhesives were used. Top Aluminum/polyimide interconnect (MCM-D) on silicon substrate in Kovar package. Bottom Multilayer thick-film (MCM-C) digital filter.

In many acute applications, microelectrodes are fixed to stationary electronics for use in anesthetized animals. For chronic use, Michigan probes have been connected to flexible polyimide interconnect cables through thermocompression gold ball bonding [48]. In this case, the polyimide cable links the microfabricated silicon probe and an external connector for long-term recording. 

Polyimides, both photodefinable and nonphotodefinable, are coming iato iacreased use. AppHcatioas iaclude planarizing iatedayer dielectrics oa iategrated circuits and for interconnects, passivation layers, thermal and mechanical stress buffers ia packagiag, alpha particle barriers oa memory devices, and ion implantation (qv) and dry etching masks. 

Hence, Tct is seen to increase with pore density and pore radius. However, a problem appears at a porous substrate when thin films are to be deposited during metallization to form interconnections, thin-film capacitors, etc.335 Sputtered material falls deep into the pores, which affects the planarity of the deposited layer and the electrical resistivity of the oxide layer underneath.335 To cope with this effect, the porous oxide should be padded by inorganic (A1203 and Si02) or organic (polyimide, negative photoresist) layers. 

Manufacture of Printed Wiring Boards. Printed wiring boards, or printed circuit boards, are usually thin flat panels than contain one or multiple layers of thin copper patterns that interconnect the various electronic components (e.g. integrated circuit chips, connectors, resistors) that are attached to the boards. These panels are present in almost every consumer electronic product and automobile sold today. The various photopolymer products used to manufacture the printed wiring boards include film resists, electroless plating resists (23), liquid resists, electrodeposited resists (24), solder masks (25), laser exposed photoresists (26), flexible photoimageable permanent coatings (27) and polyimide interlayer insulator films (28). Another new use of photopolymer chemistry is the selective formation of conductive patterns in polymers (29). 

Development of Polyimide Isoindoloquinazoline-dione in Multilevel Interconnections for Large-Scale Integration (LSI)... 

Synthesis of PIQ. Very high heat resistance is required in order for a polymer film to be used as an insulator. This is because several heat treatments over 400 C are necessary in LSI interconnection and assembly processes. An aromatic polyimide (I), a reaction product of aromatic diamine and acid dianhydride, is one of the most heat resistant polymeric materials ... 

K. Sato, S. Harada, A. Saiki, T. Kimura, T. Okubo and K. Mukai, A novel planar multilevel interconnection technology utilizing polyimide, IEEE Trans. Parts,... 

K. Mukai, A. Saiki, K. Yamanaka, S. Harada and S. Shoji, Planar multilevel interconnection technology employing a polyimide, IEEE J. Solid-State Circuits, SC-13 (4), pp 462-467, Aug. 1978. 

The increasing importance of multilevel interconnection systems and surface passivation in integrated circuit fabrication has stimulated interest in polyimide films for application in silicon device processing both as multilevel insulators and overcoat layers. The ability of polyimide films to planarize stepped device geometries, as well as their thermal and chemical inertness have been previously reported, as have various physical and electrical parameters related to circuit stability and reliability in use (1, 3). This paper focuses on three aspects of the electrical conductivity of polyimide (PI) films prepared from Hitachi and DuPont resins, indicating implications of each conductivity component for device reliability. The three forms of polyimide conductivity considered here are bulk electronic ionic, associated with intentional sodium contamination and surface or interface conductance. 

These characteristics show that perfluorinated polyimides are promising materials for waveguides in integrated optics and optical interconnect technology. The thermal, mechanical, and optical properties of perfluorinated polyimides can be controlled by copolymerization in the same manner as partially fluorinated polyimides. ... 

Stability for use in optical interconnects. In the near future, optoelectronic integrated circuits and optoelectronic multichip modules will be produced. Materials with high thermal stability will thus become very important in providing compatibility with conventional 1C fabrication processes and in ensuring device reliability. Polyimides have excellent thermal stability so they are often used as electronic materials. Furuya et al. introduced polyimide as an optical interconnect material for the first time. Reuter et al. have applied polyimides to optical interconnects and have evaluated the fluorinated polyimides prepared from 6FDA and three diamines, ODA (3), 2,2-bis(3-aminophenyl) hexafluoropropane (3,3 -6F) (4), and 4,4 -6F (2), as optical waveguide materials. 

The optimum characteristic impedance is dictated by a combination of factors. Interconnections with low characteristic impedance (<40 fl) cause high power dissipation and delay in driver circuits, increased switching noise, and reduced receiver noise tolerance (35). High characteristic impedance causes increased coupling noise and usually has higher loss. Generally, a characteristic impedance of 50-100 fl is optimal for most systems (35), and a ZQ of 50 fl has become standard for a variety of cables, connectors, and PWBs. For a polyimide dielectric with er = 3.5, a 50-fl stripline can be obtained with b = 50 xm, tv = 25 xm, and t = 5 xm. 

Copper/Polyimide Thin Film Multilayer Interconnect Structure... 

A typical polyimide (BDTA-ODA-MPD) for thin-film multilayer interconnections... 

Alternative polymers that have certain advantages over polyimides have also been introduced they include poly(phenylquinoxaline), poly(phenylquinoline), and poly(benzocyclobutenes) (PBCBs) (93,116). The PBCBs have a low curing temperature (250 °C), low dielectric constant (2.6), low dissipation factor (0.0045), and low moisture absorption (0.3%) The development of specialty polymers for packaging and high-density interconnections will continue to be an active area of research as polymer manufacturers focus on the needs of the microelectronic industry. 

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