Polyphthalaldehyde resists

We are continuing to explore the limits of the PBOCST and polyphthalaldehyde resist systems, as well as other materials that incorporate chemical amplification. 

Films of polyphthalaldehyde, sensitized by cationic photoinitiators, have been imaged at 2-5-mJ/cm in the deep ultraviolet (DUV) (see Section 3.10), at 1 pC/cm (20 kV) electron beam radiation and at an unspecified dose of Al-A x-ray radiation. The ultimate utility of this "self-developing" resist system will depend upon its efficacy as an etch barrier. It seems clear that such materials would not serve as adequate etch masks for... 

Other three-component systems based on this chemistry have made use of the following acid-labile dissolution inhibitors polyphthalaldehyde (80), ketals of (J-ketoesters (81), and compounds containing C-O-Si bonds (82). Similar resists have also been used with other radiation sources these will be discussed in subsequent sections. 

Ito and Wilson (12) have extensively investigated another resist system of this type based on polyphthalaldehyde (Equation 24). 

In a typical experiment, polyphthalaldehyde was dissolved in bis-(2-methoxyethyl) ether or cyclohexanone, to which was added the onium salt at 10 wt% to the polymer. Films spin coated on Si wafers were baked at 100°C for 10 minutes and then image-wise exposed. Optical micrographs of the resist images generated upon UV, e-beam, and x-ray radiations are exhibited in Figures 7a, b, and c, respectively. 

The very first chemical amplification resist designed for use in bilayer lithography employed Si-containing polyphthalaldehyde as a top layer resin,... 

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