Heinz Holzwarth

Structural design of ketal and acetal blocking groups in two-component chemically amplified positive DUV resists

In the present study, protecting groups of moderate stability, such as acetals and ketals, were investigated as pendant blocking groups in polyvinyl phenols. Polymers were obtained by reacting enol ethers with the phenolic side groups to form acetal or ketal blocked phenols. Decomposition temperatures, glass transition temperatures, and molecular weights of the resulting polymers were monitored and correlated with the protecting group structure. Stability of the protecting groups can be explained by protonation occurring at either of the two oxygen sites, making two cleavage routes possible. Secondary reactions of the released protecting groups in the resist film were investigated and discussed. The structure of the protecting group was designed in order to meet basic resist properties such as resolution/linearity, DOF, post exposure delay latitude and thermal stability. A Canon FPA 4500 (NA equals 0.37) and a GCA XLS exposure tool (NA equals 0.53) were used for the optimization process. A preoptimized resist formulation based on the above criteria exhibits 0.23 micrometers line/space resolution, 0.8 micrometers focus latitude at 0.25 micrometers resolution and approximately two hours post exposure delay latitude.

Relationship between physical properties and lithographic behavior in a high-resolution positive-tone deep-UV resist

A chemically amplified positive tone resist system, based on new maleimide polymers and a photoacid generator, has been developed, called MISTRAL (Maleimide-Styrene based Resist for Advanced Lithography). These polymers, which are insoluble in aqueous base, consist of two different types of monomers: blocked p- hydroxystyrenes and N-substituted maleimides. In the irradiated zones of the resist film, the phenols are regenerated by the presence of a photoacid, thereby making the resist soluble in an appropriate developer. The maleimides, on the other hand, are needed to introduce high thermal stability and good film properties. The maleimides can further be used to tailor the dissolution properties of the resist. A variety of different MISTRAL polymers have been prepared, starting from the corresponding monomers. Changes in the molecular weight, the types of monomers used and their ratio in the feed have been analyzed: a correlation study between the physical properties of the MISTRAL polymers and their lithographic behavior was systematically performed, revealing quarter micron resolution capabilities.

1,3-dioxolyl acetals as powerful crosslinkers of phenolic resin

The principle of chemical amplification has proven to be successful for the design of highly sensitive, high resolution resist materials of both positive and negative tone, respectively. This paper discusses our new approach to a high resolution, aqueous base developable deep-UV negative tone resist. It is based on the acid catalyzed cleavage of acetal blocked aromatic aldehydes, which, if treated with strong Broensted acid, react with the surrounding phenolic resin in a Friedel-Crafts type reaction, thereby leading to matrix crosslinking. Resists based on this type of crosslinking chemistry show good deep-UV transparency, have high sensitivity, and can be developed with an aqueous base.

Electron-beam and x-ray lithographic characteristics of the optical resist ARCH

The multi-component, positive acting, chemically amplified deep-UV ((lambda) equals 248 nm) resist ARCH, has been evaluated for use in proximity x-ray and electron-beam lithography. Characterization of the x-ray lithographic response of ARCH resist using a pulsed laser point source ((lambda) equals 1.4 nm) proximity print stepper resulted in a process producing sub-0.20 micrometers features at a dose of 22 mJ/cm2. A time delay study was conducted in the helium environment of the x-ray exposure tool and the results indicate that a > 30 min delay period after exposure produced no change in the resist image profile. Electron- beam exposures using a JEOL JBX 5D-II tool operating at 50 KeV delineated patterns below 0.10 micrometers on silicon. The measured exposure sensitivity was in the range of 8-16 (mu) C/cm2. Time delay experiments performed in the vacuum environment of the e-beam exposure tool over a 15 hr. time period resulted in no line size variation. These results suggest that ARCH resist represents a common material platform for the various advanced lithography programs currently under investigation for fabrication of circuits having Advanced Lithography AL 51 1995-02-19|1995-02-24 SPIEs 1995 Symposium on Microlithography ML95 171399 Santa Clara, CA, United States Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing V 2437 Process Control in X-Ray Lithography 1

Deep-UV resists based on methacrylamide copolymers

The present paper describes chemically amplified positive tone Deep-UV resists based on N-hydroxybenzyl methacrylamide (HBMAA) copolymers. HBMAAs were found to be attractive comonomers, due to their facile synthesis and their beneficial impact on the physical properties of the copolymers and the photoresists prepared from them. For example, good adhesion was provided to the silicon substrate and high glass transition temperatures were achieved which confer an appreciable thermal flow stability to the resist. HBMAA/4-tetrahydropyranyl vinyl phenol/methacrylic acid terpolymers were synthesized by radical polymerization which proceeds in a statistical manner. This allows for the monomers to be combined in the appropriate ratios, thus, tailoring the polymer properties, such as the glass transition and the dissolution rate. Two and three component resist formulations based on these terpolymrs exhibit linear resolution to 0.35 micrometers (NA 0.37). Thermal flow stability of the resists exceeded 130 degree(s)C. No auto decomposition was observed. Resists were applied without top coat and have a post exposure delay latitude of more than one hour.

Advanced positive photoresists for practical deep-UV lithography

New positive tone deep UV resists with enhanced post-exposure delay (PED) latitude and process latitude are presented. Additives and functionalized sulfone terpolymers are tailored to optimize the dissolution properties and process stability. Adjustment of the dissolution rate is used as a design criterion for optimizing the resist performance. RX 165 resist, optimized using the above criteria, exhibits 0.25 micron line/space resolution, 0.8 micrometers focus latitude at 0.275 micrometers resolution, and 1 hour post exposure delay latitude.