Outlook for 157 nm resist design

Abstract

We have measured the transparencies of a number of candidate resist materials for 157 nm, with an emphasis on determining which chemical platforms would allow resists to be used at maximum thicknesses while meeting requirements for optical density. Although ideal imaging is usually obtained at an optical density between 0.1 and 0.3 and values in excess of 0.5 can often result in nonvertical wall profiles, we chose to arbitrarily choose 0.4 as the maximum tolerable optical density. Using this analysis, our findings show that all existing commercially available resists would need to be Ͻ60 nm thick, whereas specialized hydrocarbon resists could be made ϳ100 nm thick, and new resists based on hydrofluorocarbons, siloxanes, and/or silsesquioxanes could be engineered to be used in thicknesses approaching 200 nm. We also assess the tradeoff between these thicknesses and what current information exists regarding defects as a function of resist thickness.

Characteristics of long afterglow phosphorescent calcium aluminate crystals for fluorescence thermometer application

“…The value of PL lifetime, t ¼ 11:5 ms; at room temperature is almost the same as that of spinel crystals (Cr doped MgAl 2 O 4 ) [4]. PL lifetime from CaAl 2 O 4 : Eu, Dy specimens calculated from the decay curves in Fig.…”

“…Measuring temperature based on the rate of photoluminescence (PL) decay is a potentially useful technique, because it enables temperature measurement without electro-magnetic influences [1][2][3][4][5][6][7]. In the fiber-optic thermometer system, the phosphors used for a sensor head are responsible for the accuracy and the sensitivity of the measurements.…”

Design of very transparent fluoropolymer resists for semiconductor manufacture at 157 nm

“…Two classes of polymers with low absorbance at 157 nm were identified: certain fluoropolymers and polysiloxanes [7]. In particular, Teflon 1 AF, an amorphous copolymer of tetrafluoroethylene (TFE) and perfluoro(2,2-dimethyldioxole), was found to have an absorbance of about 0.7 mm À1 at 157 nm.…”

“…Although the maximum tolerable absorbance of a resist binder polymer is still under discussion, most agree that it must be under about 2 mm À1 and preferably under 1 mm À1 . Studies showed that known resists are far too absorbing for use at 157 nm at a reasonable film thickness (Table 1) [6,7]. Styrenic and (meth)acrylate polymers are above 6 mm À1 , orders of magnitude higher than the goal value.…”

Growth and characteristics of a new long afterglow phosphorescent yttrium tantalate crystal

“…The fiberoptic thermometer based on fluorescence lifetime is one of the most promising techniques for the temperature measurement in the extraordinary environments [1][2][3][4][5][6][7][8][9]. In this thermometer system, the phosphors used in the sensor head are responsible for the accuracy and sensitivity of the measurements.…”