Photogenerators of Sulfamic Acids; Use in Chemically Amplified Single Layer Resists.

Abstract

A novel material, bis(4-t-butylphenyl)iodonium cyclamate, an alkylaminosulfonate salt capable of photogenerating a zwitterion sulfamic acid is shown to have utility in 248 and 193 nm single layer chemically amplified resists. Specifically, bis(4-tbutylphenyl)iodonium cyclamate may be employed as a self-leveled photoacid generator (PAG) in resists in which protecting groups with a low activation energy are present. Alternatively, in resins protected with high activation groups, this material serves the role of a low volatility, low diffusion photodecomposable base used in conjunction with a super-acid PAG. In both types of resists, bis(4-tbutylphenyl)iodomum cyclamate reduces resist line slimming and T-topping by respectively reducing acid diffusion and its depletion at the resist surface. The above mentioned advantages of reduced line slimming and post-exposure bake delay (PED)' stability are accomplished both in the case of the low and high activation energy resists without the need for an additional amine component. Finally, formulation of the low activation energy resist with the cyclamate PAG suppresses film thickness loss during exposure thus reducing outgassing off volatiles.

Organic Materials Challenges for 193 nm Imaging

“…The possibility of utilizing photodecomposable aminosulfonate moieties capable of affording free aminosulfonic acids has been investigated . Since in ester form these materials are inherently basic, yet upon exposure to light generate an acid, they have been called photodefinable bases (PDB).…”

“…It has been shown that the use of such materials leads to enhanced resist sensitivity because the aminosulfonate moiety is partially removed in the exposed resist film but remains unchanged in the unexposed areas where its basic properties act to limit diffusion. For instance, Figure shows the structure of two different cyclamate materials which were employed as base additives in a 193 nm single-layer resist based on a norbornene/maleic anhydride−onium salt resist platform: the photodecomposable moiety afforded a material with a resolution dose of 22 mJ/cm 2 , while the formulation containing the inert compound was far less sensitive (50 mJ/cm 2 ) . These materials effectively moderate the diffusion length of typical acids used in 193 nm chemically amplified resist formulations and impart much desired time delay stability.…”