晶圆（英语：Wafer）是指硅半导体集成电路制作所用的硅芯片，由于其形状为圆形，故称为晶圆。晶圆是生产集成电路所用的载体，一般晶圆产量多为单晶硅圆片。

晶圆是最常用的半导体材料，按其直径分为4英寸、5英寸、6英寸、8英寸等规格，近来发展出12英寸甚至研发更大规格（14英吋、15英吋、16英吋、20英吋以上等）。晶圆越大，同一圆片上可生产的集成电路（integrated circuit, IC）就越多，可降低成本；但对材料技术和生产技术的要求更高，例如均匀度等等的问题。一般认为硅晶圆的直径越大，代表着这座晶圆厂有更好的技术，在生产晶圆的过程当中，良品率是很重要的条件。

A wafer, also called a slice or substrate, is a thin slice of semiconductor material, such as a crystalline silicon, used in electronics for the fabrication of integrated circuits and in photovoltaics for conventional, wafer-based solar cells. The wafer serves as the substrate for microelectronic devices built in and over the wafer and undergoes many microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. Finally the individual microcircuits are separated (dicing) and packaged.