Design of negative resists

Negative Resists for Deep UV. There has been considerable effort recently devoted to the design of negative resists for deep-UV application. Iwayanagi and co-workers (37) have reported on the properties of resists composed of cyclized polyisoprene and several bisazides whose absorption maxima lie within the deep-UV region. Since the sensitizers do not absorb in the visible region they are referred to as "white resists" and are claimed to be 60-450 times more sensitive than PMMA. One of these resist is available commercially as... 

Briefly described below are some resists based on the above classes of reactions used in the design of negative resists, that is, nonchemically amplified cross-linking negative resists. 

The fact that tertiary alcohols can dehydrate intramolecularly with an acid as a catalyst to form olefins has been employed in the design of negative resists based on polarity switch. A good example is poly[4-(2-hydroxy-2-propyl)styrene], which undergoes acid-catalyzed dehydration to yield a stable tertiary benzylic carbo-cation, which subsequently eliminates a (3-proton to form a pendant olefinic structure (Scheme 6.18). " This intramolecular dehydration reaction converts the... 

However, one additional requirement for blast resistant design should be considered. The presence of negative pressures and rebound forces require that wall to frame connections be provided to assure proper transfer of these outward acting forces. Figure 8,2 shows an application of anchor straps to handle rebound forces,... 

The photoresponsive properties of molecular glasses also have been applied in the design of resists for semiconductor lithography. In a resist, irradiation changes the solubility of the materials, making it more or less soluble (positive or negative resist, respectively). The search for new resist materials follows the development of lithographic techniques toward deep-UV and electron beam... 

A new silicone-based negative resist (SNR) for two layer resist systems was designed and prepared. It showed excellent dry etching durability to 02 RIE, high sensitivity to electron beam, X-ray and deep UV, and high resolution. Two layer resist with SNR/AZ resist is very effective to achieve submicron patterns with high aspect ratio, and will be used for the fabrication of submicron patterns over topography such as the metallization of electrode patterns in the last step of VLSI fabrication process. 

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