Patterning of poly-para-xylylenes by reactive ion etching

Abstract

Pentacene transistor encapsulated by poly-para-xylylene behaving as gate dielectric insulator and passivation film Appl.Poly-para-xylylene family thin films deposited by vapor phase polymerization are pin hole free and are chemically inert to most acids, alkalies, and organic solvents. These properties make this material very attractive as a passivation agent on top of devices. This paper discusses the patterning of such films on planar structures by various masking techniques and the reactive ion etching (RIE) of the poly(monochloro-p-xylylene) in an oxygen-containing plasma, including details like etch rates, control of edge profiles (vertical or tapered), and the process parameters to achieve patterns of 1.5 fim wide and below.

Plasma removal of Parylene C

“…Vertical profiles were achieved when using metal or oxide masks and under conditions of low pressure, low power and a biased substrate. However, etched features exhibited significant roughness and the presence of dense micrograss structures due to redeposition of the hard mask [28,29]. Parylene removal by RIBE achieved smoother surfaces but at the expense of greatly reduced etch rates (∼10's ofÅ min −1 compared to ∼10 2 -10 3Å min −1 ) [27].…”

“…Parylene etching has been demonstrated in multiple modes including plasma etching [19,25,26], reactive ion beam etching (RIBE) [27], reactive ion etching (RIE) [28,29] and high-density plasma etching [30]. However, no attempt has been made to optimize anisotropy or employ sidewall passivation to produce high aspect ratio structures.…”

Microelectronic packaging for retinal prostheses

“…Of the three most common parylenes (Figure 1), parylene C is the most widely used in industry. The advantages of the use of parylene include its proven biocompatibility [7], its strength and flexibility (Young's modulus ≈ 4 GPa), its conformal pinhole-free room-temperature deposition, its low dielectric constant (≈ 3) and high volume resistivity (> 10 16 -cm) [8], its transparency, and its ease of manipulation using standard microfabrication techniques such as reactive ion etching (RIE) [9]. Several research groups use parylene C deposition as a method of creating a biocompatible, water-blocking seal around electrode arrays, typically fabricated using a polyimide substrate [4], [10].…”

SF6 Optimized O2 Plasma Etching of Parylene C

“…It is a chemically stable, USP (United States Pharmacopeia) Class VI biocompatible, and flexible material that has been widely implemented in microfluidics and bioMEMS applications such as microvalves [ 1 ], accelerometers [ 2 ], flexible electrodes [ 3 , 4 ], and neural probes [ 5 , 6 , 7 ]. To pattern the Parylene C, different fabrication techniques have been proposed, such as wet etching using chloronapthelene or benzoyl benzoate [ 8 ], dry etching based on O 2 plasma [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ], thermal imprinting or micro-molding [ 16 , 17 ] and laser micromachining [ 18 , 19 , 20 ]. Among the existing fabrication strategies, the dry etching technique is a relatively clean and effective method that is suitable for batch fabrication of Parylene C microstructures.…”