Photodefinable poly(decylnorbornene-co-epoxidenorbornene) copolymer has been developed as a dielectric material for electronic packaging applications. The photodefinition properties of the polymer are affected by the copolymer composition, the concentration of photoactive compound and the process conditions. In particular, ultrahigh contrast conditions were found to promote the fabrication of vertical sidewall structures. For photodefined structures, the vertical sidewalls were obtained at specific formulations and process conditions. Under different conditions, non-vertical features were observed. Rutherford backscattering analysis (RBS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to study the photodefinition properties. In this article, a mechanism based on the diffusion of photoactive compounds from the exposed area to the unexposed area is presented. The transport of photoactive compounds takes place through the free volume that results from solvent evaporation. The diffusion of the photoactive compounds to the surface of the polymer film results in a higher concentration of photogenerated acid at the surface. The movement of the photoactive compounds occurs in both the in-plane and through-plane directions. (C) 2004 Wiley Periodicals, Inc.

In the microelectronics industry, the drive for increasing device speed, level of functionality and shrinking size has placed significant demands on the performance characteristics of polymer dielectrics. In this study, a negative acting, photodefinable dielectric formulation based on a copolymer of decylnorborne (decylNB) and epoxynorbornene (AGENB) was investigated for use in electronics packaging. The structure-property relations of this copolymer were investigated. Copolymer composition and processing conditions were shown to significantly affect the properties of the final polymer films. A lower content of AGENB results in lower moisture absorption, dielectric constant, modulus and residual stress, but it compromises multilayer capability. High crosslink density lowers the dielectric constant but increases the modulus and residual stress. (C) 2004 Wiley Periodicals, Inc.

Low dielectric constant materials are critical to meeting the demand for continual reduction in feature sizes and increase in interconnect density required for future high-speed microelectronic devices. Polymers based on functionalized norbornenes are inherently attractive for these applications as they exhibit good electrical properties such as a low dielectric constant and appealing mechanical properties. Although polynorbornenes inherently possess properties that are attractive for microelectronics packaging, films of these polymers are not solvent-resistant. Solvent-resistant crosslinked films can be attained by generation of acid species to promote cationic crosslinking of epoxide side groups. This article is the second part of a two-part study investigating the crosslinking of a copolymer of decyl norbornene and epoxide norbornene. In the first part of this study, it was proposed that epoxide decomposition reactions are also possible at cure temperatures greater than 160degreesC. This decomposition mechanism results in the complete loss of crosslinkable epoxide groups while leaving the norbornene backbone intact. Although crosslinking and decomposition reactions have independent mechanisms, both reactions directly affect the level of crosslinking. In this part of the study, the solvent swelling behavior, tensile modulus, elongation to break, and residual stress were investigated for polymer films cured under various conditions to validate the proposed mechanisms. The trends observed with these properties are consistent with the counteracting nature of epoxide crosslinking and decomposition reactions. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1020-1029, 2004.

The miniaturization of microelectronic devices has created a demand for new low-dielectric-constant materials to be used as insulating layers between metal interconnects. In this study, a functionalized polynorbornene consisting of a copolymer of decyl norbornene and epoxide norbornene has been investigated as a low-temperature curing dielectric. Polynorbornenes possess properties that are attractive for microelectronics packaging; however, films of these polymers must be crosslinked in order to obtain the solvent resistance and low solvent swelling necessary for multilayer applications. Crosslinking of these materials was achieved by acid-catalyzed cationic crosslinking of epoxide side groups. The reactions that occurred during higher temperature curing of epoxy functionalized norbornene films were studied using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis. Epoxide crosslinking and epoxide decomposition reactions were identified and studied as a function of temperature and time. (C) 2003 Wiley Periodicals, Inc.

High-density packaging and interconnection applications frequently involve the use of polyimide-based materials as interlevel dielectrics for multilevel interconnection schemes. Surface planarity after each polymer layer is very important to the fabrication of multilayer structures. Highly nonplanar surfaces were observed in a multilayer test structure, fabricated using a thermally cured polyimide (Ultradel 7501). In this study, the effect of a novel cure technique involving electron beam (e-beam) exposure on multilayering and planarization behavior in Ultradel 7501 is investigated. Planarization measurements were conducted on different feature sizes and at various locations on the wafer in order to investigate the effect of solvent exposure, time and area of contact between multiple layers. The degree of planarization was found to improve from -206% for a thermally cured case to +15% for an e-beam cured sample. Analysis of the solvent induced polymer swelling and its effect on multilayer planarization of Ultradel 7501 is presented.

The rapid development of microelectronic industry has created great demand for low dielectric constant (low-k) materials. A functionalized polynorbornene polymer is being investigated for this purpose. Epoxide and alkyl side groups are attached to the polymer backbone, affording the polymer film good mechanical and chemical properties. Additionally, the polymer film can be made photo-definable by the addition of photo-active compounds that initiate crosslinking reaction on UV exposure. The reaction mechanism of poly[decyinorbornene-co-epoxidenorbornene] was studied. The structure-property relations of polymer film were investigated. Copolymer compositions and process conditions affect the properties of the polymer film. A lower content of epoxidenorbornene results in lower dielectric constant, lower residual stress, better adhesion, better photodefinition, but poor multilayer capability. Good photodefinition is achieved by using lower exposure dose, lower post bake temperature and shorter post bake time.

The rapid development of the microelectronics industry creates high demand for low dielectric constant (low-k) materials. Polynorbornene (Avatrel/sup TM/) is a new photodefinable dielectric material developed by the BF Goodrich Company. A type of cationic photoinitiator, onium salts, is used to initiate the crosslinking reaction of epoxide groups. The reaction mechanism of poly(decylnorbornene-co-epoxidenorbornene) was studied. The structure/properties relationships of the polymer film were investigated. Copolymer composition and process conditions affect the properties of the polymer film. A lower epoxidenorbornene content results in lower dielectric constant, lower residual stress, better adhesion, and good photodefinition, but poor multilayer capability. Lower exposure dose, lower post bake temperature and shorter post bake time improve photodefinition.

Polymers are widely used in the microelectronics industry as thin-film interlevel dielectrics layers between metal lines, as passivation layers on semiconductor devices and in various packaging applications. As multiple layers of polymer and patterned metal are constructed, the ability of these polymers to planarize topographical features becomes increasingly important. In this study, the degree of planarization (DOP) for five commercially available polymers has been examined for three different structural configurations with the intent of simulating practical applications. Specifically, this study investigates single layer planarization, multiple coat planarization, and planarization of metal lines patterned on a polymer base. This study also examines the effects of orientation of the metal structure to polymer flow during spin casting and location on the wafer. The polymers are selected to investigate different polymer chemistries frequently used in the microelectronics industry. The underlying structures were fabricated using standard photolithography and electroplating techniques. Feature dimensions include 25-200 /spl mu/m line spacings and widths with the polymer overcoat thickness being twice the height of the underlying structures.

In order to realize the performance advancements in silicon technology, complementary advances in packaging technology are necessary. Advance materials must be developed to achieve the full potential of advance packaging processes. A family of dielectric polymers based on polynorbornene is under development to address the broad needs of high density packaging (HDP). Properties common to this family of materials include a low dielectric constant low loss tangent low moisture absorption, good adhesion, and isotropic properties. This family's tailorability allows materials to be developed for a number of applications including wafer redistribution, passivation, sequential, and parallel build-up processes.