Lithographic applications

Regions on top of the spots are PMMA-rich (transparent) and one looks through to the substrate (black). In the lower left corner the upper half of the film is removed for better viewing of the film closer to the chemical pattern. (Reproduced with permission from [34]. Copyright (2006) by the American Physical Society.) 

Two recent publications provide additional examples of the CD control abilities of directed assembly of block copolymers, but also demonstrate for the first time the opportunity for resolution enhancement with block copolymer films directed to assemble on chemical patterns [81, 82]. In one case, cylinder-forming PS-h-PMMA was directed to assemble on a chemical pattern comprised of hexagonally arranged 

Pattern Rectification Density Multiplication Pattern Rectification Density Multiplication 

6 International Technology Roadmap for Semiconductors - Emerging Research Materials. 2007 edn. International SEMATECH, Austin, TX. 

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To date, we have exercised these materials in basically three types of multilayer lithographic applications (1) as short wavelength contrast enhancing layers, (2) as imagable 02-RIE resistant materials in bilayer processes and (3) as radiation sensitive materials for multilayer, e-beam processes. 

The TT-electron system-substituted organodisilanes such as aryl-, alkenyl-, and alkynyldisilanes are photoactive under ultraviolet irradiation, and their photochemical behavior has been extensively studied (1). However, much less interest has been shown in the photochemistry of polymers bearing TT-electron substituted disilanyl units (2-4). In this paper, we report the synthesis and photochemical behavior of polysiloxanes involving phenyl(trimethylsilyl)-siloxy units and silicon polymers in which the alternate arrangement of a disilanylene unit and a phenylene group is found regularly in the polymer backbone. We also describe lithographic applications of a double-layer system of the latter polymers. 

The lithographic applications of a double-layer resist system in which the poly[p-(dimethyldiphenyldisilanylene)phenylene] film (0.2 ym thick) was used as the top imaging layer have been examined (K. Nate, T. Inoue, H. Sugiyama and M. Ishikawa, J. Appl. Polym. 

Loss of bromine produces dramatic changes in physical properties between exposed and unexposed areas and provides the basis for lithographic applications. 

At this stage, the potential of E-beam induced reverse electron transfer in conducting organic charge transfer salts for lithographic applications is unclear. However, these materials do possess a rather unique combination of properties that may be of considerable value in future applications where traditional resist materials may be unsuitable. Some of the key features of these new resists are summarized below ... 

TABLE 1. Physical Properties of Selected Step 5 Polymers Used as Resist Materials in Lithographic Applications 1... 

Additional photoresist materials containing 1,1,1,3,3,3-hexafluoroisopropyl alcohol, (I) and (II), were prepared by Harada et al. (1) and Maeda et al. (2), respectively, and used in lithographic applications. 

Functionally Substituted Novolak Resins Lithographic Applications, Radiation Chemistry, and Photooxidation... 

Dry-Film Resists Based on Radical Photopolymerization. Photoinitiated polymerization (PIP) is widely practiced in bulk systems, but special measures must be taken to apply the chemistry in lithographic applications. The attractive aspect of PIP is that each initiator species produced by photolysis launches a cascade of chemical events, effectively forming multiple chemical bonds for each photon absorbed. The gain that results constitutes a form of "chemical amplification" analogous to that observed in silver halide photography, and illustrates a path for achieving very high photosensitivities. 

Fig. 32. Acrylic polymers found in CA resists designed for lithographic applications using 193 nm light.

We have successfully employed the trimethylsilylmethyl appendage to effect oxygen RIE resistance in both positive and negative acting electron-beam resist systems (10,11). The relatively compact nature of this substituent allows the preparation of glassy polymers useful for lithographic applications. The preparation and characterization of select trimethylsilylmethyl substituted resists will be presented in addition to a study of their radiation chemistry and lithographic properties. 

The dependence of both the jjjax and of the polymer on molecular weight suggests that any process which reduces the molecular weight will result in a bleaching of the initial absorption. This behavior is important for many lithographic applications (vide infra). In this regard, the irradiation of a 0.2 /im thick film of... 

Polysiloxanes. The initial reports of the utility of polysiloxanes for lithographic applications spurred several research groups to further investigate this class of materials. The problem of low Tg was addressed by preparing chloromethylated poly(diphenylsiloxane) 16, 17). More recently, poly(sil-sesquioxanes) 18, 19) have been reported as sensitive, negative, e-beam, ion-beam, and UV resists. These soluble, ladder -type polymers prepared by the hydrolysis of substituted chloro- and alkoxysilanes are high-Tg materials (150 °C) with high silicon contents. 

PHOTOCHEMICAL SURFACE REACTIONS OF POLYMERIC SYSTEMS LITHOGRAPHIC APPLICATIONS... 

Photochemical Surface Reactions of Polymeric Systems Lithographic Applications (H. Hiraoka)... 

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