UC San Diego

This dissertation introduces a kind of new gray-scale technology. The new gray-scale technology uses a carbon- based light-attenuating material. This material can reach a very high optical density (̃3.0) for deep ultraviolet (DUV) lithography applications. This property is out the reach of the often-used High-Energy-Beam-Sensitive (HEBS) gray-scale mask. HEBS gray-scale mask cannot be used for wavelength below 300 nm and it cannot provide enough optical density at wavelengths shorter than 350 nm for high-resolution component fabrication. Higher optical density at shorter wavelengths means that the components of more levels and with higher resolution are achievable. Compared with Binary Half-Tone (BHT) gray-scale mask, the new mask offers a much higher resolution. Two-beam-current method is invented for the e-beam writing in the fabrication of gray-scale masks. Compared with the simpler single-current method, two-beam-current method offers two important advantages. First it can achieve a much larger dynamic range for the e-beam exposure. The second advantage is the writing time for a gray-scale mask could be reduced significantly when a large pattern is to be written. By applying the new gray-scale mask in DUV and UV lithography respectively, gray-scale patterns were successfully generated in optical resists. Finally devices were fabricated after the gray-scale patterns in resists were transferred into the substrate material in the etching step. Different micro-structures with different resolution and depth requirements have been fabricated successfully. The carbon-based material has a big hardness, comparable to diamond film, and stays at the quartz surface very firmly. The life time of the mask is comparable to the normal chrome mask used in semiconductor industry, and thus pretty long. This new gray-scale technology could also lead to lower-cost mass production of higher quality micro- and meso-scale micro-devices in different substrates, e.g. quartz and silicon et al.