Bilayer resist processing

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 2. Inorganic/organic bilayer resist processes.

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

Fig. 4. Polynucleotide array fabrication processes using polymeric photoresists. Left. A single layer resist process. Right A bilayer process using a protective underlayer...

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 10 The use of a polysilane resist in a bilayer photolithographic process...

Because of their desirable properties and radiation sensitivity, polysilanes have been used in a variety of microlithographic applications as (1) mid-UV contrast-enhancing materials, (2) imaging layers in a variety of bilayer lithographic processes, and (3) new resist materials for ionizing radiation. 

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... 

The three main approaches to multilayer resist imaging systems (see Chapter 16 for details) include (i) hard mask (HM) processes, (ii) top surface imaging (TSI) processes requiring latent image formation only near the surface of the resist, thus circumventing any transparency requirements, and (iii) bilayer resist (BLR)... 

The conventional bilayer resist systems in which the top imaging layer (typically organosilicon polymer) also serves as an etch mask was first proposed by Hatzakis et al. in 1981, ostensibly for electron-beam lithography. Since then, a number of organosilicon resists for bilayer resist systems have been reported for use in near-UV, DUV, mid-UV, electron-beam, and x-ray applications, a good review of which has been provided by Ohnishi et al. In recent times, negative-tone resist systems and processes based on silicon-backbone polymers such as polysilanes,polysilynes, and plasma-deposited polymers have been developed for 193-nm lithography. 

S. Birkle, Chemical amplification of resist lines a novel sub half micron bilayer resist technique for NUV and deep UV lithography, Proc. SPIE 1262, 528 (1990) M. Sebald, H. Berthold, M. Beyer, R. Leuschner, Ch. Ndlscher, U. Scheler, R. Sezi, H. Ahne, and S. Birkel, Application aspects of the Si CARL bilayer process, Proc. SPIE 1466, 227 237 (1991) R. Leuschner, M. Beyer, H. Bomdorfer, E. Kiihn, Ch. Nolscher, M. Sebald, and R. Sezi, CARL resist A technology for optical quarter micron resolution and below, in Proc. SPE Reg. Tech. Conf. Photopolym., Ellenville, NY, pp. 215 224(1991). 

Yang H, Jin A, Luo Q et al (2008) Electron beam lithography of HSQ/PMMA bilayer resists for negative tone lift-off process. Microelectron Eng 85 814—817... 

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. 

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