In this study, we developed three different photolithigraphic processes to pattern the semiconductor layers in organic thin-film transistors (OTFTs). We measured electrical characteristics before and after the patterning processes and compared the differences between these processes. We found that the patterning process using conventional photoresists was not suitable for hydrophobic materials, such as poly(3-hexylthiophene). We further applied another protection layer, poly(4-vinylphenol) on the semiconductor layers. However, the active layer was also damaged during the stripping process. Therefore, we developed a two-step, solvent-free etching method, and successfully patterned the semiconductor layer in OTFTs. Finally, we used this approach to fabricate organic ambipolar devices, which can be potentially used for constructing CMOS-like inverters.