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

Abstract

Thermal effects accompanying vacuum deposition of poly(chloro‐para‐xylylene) in the temperature range between −196 and 0°C have been studied using two separate methods. One is based on the recording of the rate of evaporation of liquid nitrogen and it is used for the deposition at −196°C, and the second involves the recording of changes in the substrate temperature and is used for the deposition in the range of −162 to 0°C. These methods enable us to observe two distinct effects: fast (discrete), resulting in the appearance of sharp, exothermic spikes; and slow (continuous), resulting in the shift of the baseline. The shift of the baseline exhibits a well‐defined maximum at about −65°C and this temperature is attributed to the melting point of the monomer. The fast process always occurs below this temperature and is explained as a solid state, chain addition polymerization. The quantification of the heat effect at −196°C strongly suggests that the quinonoid form of the monomer participates in the propagation step of this chain reaction. The fast (solid state) and the continuous modes of polymerization may occur simultaneously in the range of about −140 and −65°C. The frequency of the initiation which is the formation of dimer radical seems to control the occurrence of these two modes of polymerization.

Micromachining of Parylene C for bioMEMS

“…Furthermore, processes that inhibit these deposition mechanics can enable the selective deposition of Parylene. In most cases, heat was used to prohibit the deposition of Parylene using heaters fabricated on the substrate, as a localized temperature increase (>140°C) can reduce the deposition rate in that region . Another technique utilized deposited transition metals (e.g.…”

Plasma removal of Parylene C

“…The thickness of deposited Parylene is a function of substrate temperature [32,33] so biased resistors were used to generate a localized heat gradient that prevented deposition in regions held above 70…”

Vapor Deposition Polymerization of para-Xylylene Derivatives-Mechanism and Applications

“…At temperatures below its freezing point, the monomer condenses as a crystalline solid. Results of thermal measurements during Parylene N and Parylene C deposition at very low temperatures indicate that freezing point of p-xylylene is located in the vicinity of -73°C 13) , while that of chloro-p-xylylene nears -65 12) . The same results, together with those obtained by Treiber et al 11) , strongly indicate an existence at low temperatures of two exothermic phenomena, substantially diŠering with their kinetics 12,13) .…”

“…These data strongly indicate a post-deposition growth of polymer chains due to a recombination of macroradicals. The post-deposition polymerisation of xylylenes has also been demonstrated by measurements of the heat of reaction, which for both Parylene N and Parylene C keeps on evolving from the system long after the termination of deposition [11][12][13] .…”