Characterization of Vapor‐Deposited Paraxylylene Coatings

Baker, T. E.; Bagdasarian, Sergey; Fix, G. L.; Judge, John

doi:10.1149/1.2133448

Cited by 12 publications

(1 citation statement)

References 4 publications

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“…Parylene (a trade name for poly( p -xylylene)-based polymers) is available as parylene-N, -C, -D, -AF4, and so forth, where all but the first are functionalized derivatives of poly( p -xylylene). Over the years, numerous scientific research studies have reported on paralyne films, including the morphology and crystal structure of films deposited at various substrate temperatures, − thermal properties, − poly( p -xylylene) properties as gas barriers, ,,− mechanical and electrical properties of the films, ,, mechanism of the polymerization process, ,− and various applications of the parylene polymers. − ,, …”

Section: Introductionmentioning

confidence: 99%

Chemical Vapor Jet Deposition of Parylene Polymer Films in Air

et al. 2015

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Parylene films are commonly used as transparent, flexible coatings in electronic devices and biomedical applications, exhibiting barrier properties against corrosion, low dielectric constant, and moisture resistance. Reactive vapor deposition of parylene results in conformal coverage of features at room temperature, which is advantageous for passivating, for example, organic optoelectronic devices. Conventional parylene deposition methods, however, coat surfaces virtually indiscriminately and utilize separate chambers for vaporization, pyrolysis, and polymerization, resulting in a large footprint and limited processing integration ability, especially at a laboratory scale. Here, we demonstrate the vaporization and pyrolysis of the di-p-xylylene (parylene dimer) in a single compact nozzle, producing a jet of monomer that polymerizes into a film upon contact with the substrate at room temperature. A guard flow jet is employed to shield the reactive monomer molecules en route to the substrate, thereby enabling polymer deposition and patterning in ambient atmosphere. We present an analytical model predicting film growth rate as a function of process parameters (e.g., gas flow rate and source, pyrolysis & substrate temperatures). The effect of jet flow dynamics on film morphology is also discussed. A 100% increase in the lifetime of air-sensitive OLEDs is demonstrated upon encapsulation of the devices with parylene-N film deposited by this technique. Potential advantages of this approach include increased material utilization efficiency, localized conformal coating capabilities, and an apparatus that is compact, inexpensive, and does not require vacuum.

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Section: Introductionmentioning

confidence: 99%

Chemical Vapor Jet Deposition of Parylene Polymer Films in Air

et al. 2015

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Polymerization of para‐xylylene derivatives (parylene polymerization). I. Deposition kinetics for parylene N and parylene C

Kramer

Sharma

Hennecke

et al. 1984

J. Polym. Sci. Polym. Chem. Ed.

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Kinetic aspects of parylene N [unsubstituted poly(para‐xylylene)] and Parylene C [monochlorosubstituted poly(para‐xylylene)] were studied. The conversion of starting material (dimer of either p‐xylylene or chloro‐para‐xylylene) to polymer is quantitative (ca. 100%). Consequently, the total polymer formed in a closed system is directly proportional to the amount of dimer charged. However, the percentage of the total amount of polymer formed which deposits on substrate surfaces, placed in the deposition chamber, as well as the polymer film growth rate are dependent on operational factors such as the temperature of the substrate, sublimation of dimer temperature, flow pattern of the reactive species, etc. Parylene C, being a heavier and more polar molecule, has the tendency to deposit easily in the deposition chamber compared to the deposition of Parylene N. Parylene C also has a higher ceiling temperature for deposition than Parylene N. This situation has been investigated from the viewpoint of excess thermal energy which hinders polymer formation (deposition) due to the exceedingly high entropy change necessary for polymer deposition to occur. The addition of a cool (i.e., room temperature) inert gas was shown to increase the deposition of Parylene N on substrate surfaces placed in the deposition chamber. The deposition increase and acceleration of deposition (film growth) rate were found to be related to the size and molecular weight of the inert gas pressure maintained in the system. The accelerating effect is explained by the increase in third‐body collisions to dissipate the excess thermal energy of the reactive species.

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Polymerization of para‐xylylene derivatives (parylene polymerization). III. Heat effects during deposition of parylene N at different temperatures

Gazicki¹,

Surendran²,

James³

et al. 1986

J. Polym. Sci. A Polym. Chem.

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SynopsisThermal effects accompanying t h e vacuum deposition of poly-para-xylene (Parylene N ) at different temperatures have been studied by following the changes in the temperature of the substrate. Similarly to the case of polychloro-pun-xylylene (Parylene C), two distinct exothermic effects were observed; one discrete, resulting in sharp exothermic spikes and the other continuous, resulting in the shift of the baseline. The spike effect, attributed to the solid-state polymerization of pam-xylylene, is observed at the low-temperature range, the upper limit of which moves higher for higher deposition rates. The shift of a baseline as a function of deposition temperature exhibits two maxima, one independent of deposition rate and the second moving toward higher temperatures (that is, toward the first maximum) for higher deposition rates. First maximum falls at about -72°C and is attributed to the melting point of pam-xylylene crystals. X-ray diffraction studies of polymer samples have shown that the existence of the second maximum is always followed by the appearance of a n additional crystalline phase in the respective range of deposition temperatures. When the deposition rate is high enough, the second maximum merges with the first one, or virtually disappears. Under such conditions the new crystalline phase is no more detectable. It is postulated that the evolution of the additional amount of heat resulting in the appearance of the second maximum is due to the cyclization reaction and the formation of cyclic oligomers. This reaction very likely requires a particular spatial arrangement of monomer molecules and, therefore, it is suggested to take place in certain domains of the crystalline lattice. GAZICKI ET AL.ful in all technologies requiring high-quality coatings. The very advantageous combination of these two factors, that is, the ease and the conformity of the deposition with the excellent properties of the coatings, has been a key to the success of Parylene technology. This success is evident in at least two modern high-technology applications, namely, in microelectronics as protective coatings for integrated circuitry6q8 and in neurology as insulating coatings for implantable neural microelectrodes. l0-l2 Very recently, the Parylene deposition process has also been reported to successfully meet the requirements for another high-technology application, high-quality coatings for laser-fusion targets. l3As often is the case, the successful application of Parylene technology has preceded a detailed understanding of the deposition mechanism. Although a significant amount of information concerning the chemistry of the process is available, l.14-16 the physicochemical aspects of the deposition are not yet fully understood. Particularly, the influence of factors such as the temperature of deposition or the rate of dimer sublimation has not been investigated thoroughly. An attempt has, therefore, been undertaken in this series to study the influence of these factors on the mechanism of deposition, and particula...

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Characterization of Vapor‐Deposited Paraxylylene Coatings

Cited by 12 publications

References 4 publications

Chemical Vapor Jet Deposition of Parylene Polymer Films in Air

Chemical Vapor Jet Deposition of Parylene Polymer Films in Air

Polymerization of para‐xylylene derivatives (parylene polymerization). I. Deposition kinetics for parylene N and parylene C

Polymerization of para‐xylylene derivatives (parylene polymerization). III. Heat effects during deposition of parylene N at different temperatures

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