Bilayer resist

Fig. 36. Representative bilayer resist systems. Both CA and non-CA approaches are illustrated (116—119). (a) Cross-linking E-beam resist, 193-nm thin-film imaging resist (b) acid-cataly2ed negative-tone cross-linking system (c) positive-tone CA resist designed for 193-nm appHcations and (d) positive-tone...

Organosilicon polymers are especially important as imaging layers in bilayer resist processes(1). A wide range of organosilicon resist materials, in which the organosilicon compound has been incorporated either into the polymer main chain or into pendant groups, has appeared in the literature(2-8). However, almost all polymers have been... 

Figure 1. The processing steps for a bilayer resist using 02-RIE.

Figure 9. Poly silane bilayer resist, top layer 0.25 am experimental polysilane, bottom layer 1.0 am of hardbaked photoresist, projection printed at 313 nm with 02-RIE image transfer.

Figure 2. Inorganic/organic bilayer resist processes.

The inorganic/organic bilayer resist technology has been successfully applied to the A1 interconnection process in bipolar LSI fabrication, including the 1 kbit RAM and several repeater ICs for optical communication systems (6). The minimum feature size of the patterns was 1.5 fim for lines and 1.0 fim for spaces. In order to further evaluate the lithographic... 

Figure 3.52. Patterns formed in a bilayer resist system consisting of a 1.2-p.m-thick planarizing layer of PMMA and a 0.4-[im-thick RD2000N imaging resist. Reproduced with permission from reference 19. Copyright 1984 Technical...

It behaves as a negative photoresist in bilayer resist systems and is highly sensitive to electron beam, X-ray or UV radiation whilst being resistant to 02 reactive ion etching243. 

Fig. 150 High aspect ratio image printed in 248 nm bilayer resist by oxygen RIE [422c]...

Polysilsesquioxanes have found a use in the design of 193 nm bilayer resist. The phenol structure has been replaced with cyclohexyl carboxylic acid for... 

Copolymers of 4-silyloxy-a-methylstyrene or silyl methacrylate with meth-acrylonitrile were prepared by radical copolymerization of silyl monomer or by silylation of acidic copolymer and evaluated as 157 nm positive bilayer resists [437]. 

LER and resist outgassing during exposure are major issues in bilayer lithography [438, 439]. Si species generated from a bilayer resist during exposure could badly contaminate lenses. Thus, formation of gaseous products must be minimized by proper selection of deprotection chemistry and resist components. 

Phenolic resists can be silylated also after wet development with aqueous base [463,464]. In the silicon-added bilayer resist (SABRE) process (Fig. 165), a di-azoquinone/novolac resist is coated on a top of a planarizing layer and imaged in the conventional fashion by UV exposure and aqueous base development [463]. The phenolic polymer remaining in the unexposed area after development is silylated in a gas phase or in solution to provide 02 RIE resistance for dry etching of the underlying layer [463,464]. This bilayer scheme takes advantage of high contrast aqueous base development to produce square resist profiles, which are then converted to a well-defined Si mask by silylation for 02 RIE pattern transfer. Thus, a poor silylation contrast sometimes encountered... 

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