The authors have investigated a range of poly(methylmethacrylate) (PMMA) development temperatures as low as -70 °C and characterized their effect on the resolution of PMMA as an electron resist. The results show that cooling, in addition to reducing the sensitivity of the commonly used positive-tone mode of PMMA, also increases the sensitivity of its less commonly used negative-tone mode. They have shown that the resolution-enhancing properties of cold development peak at approximately -15 °C as a result of these competing sensitivity changes. At lower temperatures, the high doses required to expose the resist produce significant cross-linking of the polymer, altering its solubility properties and sharply degrading the contrast. If the correct development temperature is used, however, sub- 10 nm features are readily achievable in PMMA-based scanning electron-beam lithography.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|State||Published - 2007|
Bibliographical noteFunding Information:
The authors would like to acknowledge Joel Yang, Mark Mondol, Vikas Anant, and Jim Daley for many useful discussions of the theory and practice of PMMA development. All lithographic work was done in the MIT shared Scanning-Electron-Beam Lithography facility in the Research Laboratory of Electronics (SEBL at RLE). Contrast measurements were performed in MIT’s CMSE Shared Analytical Laboratory. All other processing and analysis took place in the MIT Nanostructures Laboratory. This work was funded in part by NERC and AFOSR. B.C. would like to acknowledge support from the QuaCGRS Fellowship program.