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Para-Xylylene Patterning

IP.com Disclosure Number: IPCOM000045551D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Grebe, KR: AUTHOR [+2]

Abstract

Passivation coatings of (poly)para-xylylene can be precisely patterned by masking with oxidation-resistant materials and subsequently subtractively etching in an oxidizing environment.

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Para-Xylylene Patterning

Passivation coatings of (poly)para-xylylene can be precisely patterned by masking with oxidation-resistant materials and subsequently subtractively etching in an oxidizing environment.

The ductile and plastic behavior of para-xylylene materials (e.g., parylene passivating material) makes them suitable for cryogenic applications. It is also possible to use these films as insulation layers for microelectronic circuits because of their low dielectric constant (approx. 3) and low loss properties. The low dielectric constant is most attractive for high speed microstrips or strip lines.

One of the disadvantages of using para-xylylene materials is that they are difficult to pattern, especially in micron or submicron dimensions. There are, however, a number of masking materials to pattern para-xylylene materials using oxygen plasma or other oxidizers such as CF(4)-O(2). Removal using oxygen plasma can be achieved in both the reactive ion etching mode as well as in the plasma etching mode. By the same principle, the para-xylylene materials can be removed in the reactive ion-beam etching mode using oxygen ion beams. In the RIE (reactive ion etching) mode the etch rate can be from less than 100 Angstroms/minute to more than 1000 Angstroms/minute depending on the bias voltage and power density. Masking for the etching can be achieved by photo-patterning metal, insulator thin films, or photo-sensitive organic materials.
1. METAL
a. Deposit, on top of the para-xylyene layer 1, a metal

thin film 2.
b. The metal thin film can be defined by lift-off (Fig. 1A), or

by wet or dry subtractive etching (not illustrated).

The metal film thickness is not crucial

(e.g.,<1000 Angstorms), and can be Al, Au, Cr,

Cu, Nb, Ag, etc. (Fig. 1B).
c. After photoresist removal, para-xylylene layer 1 is etched in

oxygen plasma. Metal thin film 2 is not etched or is

etched very little (Fig. 1C).
d. The metal thin films (surface oxidized) can be subsequently

removed (by etching) or left in place depending on

compatibility of applications (Fig. 1D). #:AB 2. INSULATOR
a. Deposit an insulator thin film 2 onto para-xylyene layer 1.
b. Thin film 2 is an insulator film defined by lift-off or

subtractive etching (Fig. 1A). The insulator film

thickness is not crucial, e.g., <2000 Angstroms. Materials

can be SiO, SiO(2), etc. (Fig. 1B).
c. After lift-off or photoresist removal, the para-xylylene

layer 1 is etched in the oxygen plasma. Insulator

film 2 is only slightly etched (mostly by sputter

removal) by oxygen plasma (Fig. 1C).
d. The insulator...