In chip manufacturing, the “substrate” not only determines the physical foundation of the wafer but also profoundly affects the electrical performance, reliability, yield, and process compatibility of the devices. But have you noticed? The vast majority of CMOS chips use <100> crystal-oriented silicon substrates. Why does almost the entire industry “favor” the <100> orientation? Today, we will clarify this from the perspectives of material structure, device characteristics, and process controllability.