In order to develop lightweight and high angular resolution x-ray mirrors, we have investigated hot plastic deformation of 4 in. silicon (111) wafers. A sample wafer was deformed using hemispherical dies with a curvature radius of $1000\mathrm{mm}$ . The measured radius of the deformed wafer was $1030\mathrm{mm}$ , suggesting that further conditioning is indispensable for better shaping. For the first time to our knowledge, x-ray reflection on a deformed wafer was detected at Al $K_{\alpha }$ $1.49\mathrm{keV}$ . An estimated surface roughness of $<1\mathrm{nm}$ from the x-ray reflection profile was comparable to that of a bare silicon wafer without deformation. Hence, no significant degradation of the microroughness was seen.