Characterization of Butyl Tin Photoresists with Electron Stimulated Desorption and Temperature Programmed Desorption

  • Authors:
    Ryan Frederick (Oregon State Univ.), John T. Diulus (Oregon State Univ.), Douglas Keszler (Oregon State Univ.), Eric Garfunkel (Rutgers), Gregory S. Herman (Oregon State Univ.), Sumit Saha (Oregon State Univ.), Jenn Amador (Oregon State Univ.), Mengjun Li (Rutgers)
    Publication ID:
    Publication Type:
    Received Date:
    Last Edit Date:
    2438.001 (Oregon State University)


Performance enhancements of inorganic resists may transform next generation photolithography. These resists combine the potential for high-resolution patterning, while having high-sensitivity to extreme ultraviolet (EUV) radiation. Incorporating high-absorption coefficient elements with radiation sensitive ligands can significantly improve resist sensitivity. Upon EUV exposure a range of low-energy electrons (Ekin < 90 eV) are produced in the resist. These low-energy electrons drive chemistries that induce relative solubility differences between the exposed and unexposed regions. In this presentation, we discuss the patterning mechanisms for thin film n-butyl tin oxide hydroxide (BuSnOOH), which is a model organotin-based inorganic photoresist. We have characterized thermal and electron induced decomposition of BuSnOOH by temperature programmed desorption (TPD) and electron stimulated desorption (ESD), respectively. From the TPD studies, we find a desorption peak at ~653 K, which is due to decomposition of BuSnOOH, and the resulting desorption of the butyl ligand. A series of thermal desorption energy curves were obtained by inversion of the Polanyi Wigner TPD model, and we estimated that the butyl group desorption energy was 2.15eV - 2.7 eV for a range of prefactor values. This energy roughly corresponds to the dissociation energy for the Sn-C bond (2.05 eV). From the ESD studies, we find that the main desorption product is also related to the butyl group. We found that low-energy electrons (Ekin = 80eV) are very effective for the dissociation of the Sn-C bond. Desorption cross sections, obtained from the ESD data, were determined to be ~4.2 Ă— 10-14 cm2. For both TPD and ESD we find that both thermal and electron stimulated chemistries are associated with breaking the Bu-Sn bond. We will describe how the combination of TPD and ESD allows us to gain mechanistic insights for organotin-based inorganic resists.

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