Why Are Silicon Wafers as Thick as They Are

Silicon wafers have been the building blocks of the electronic industry for more than 40 years. Wafer size increased from 2 in. in diameter in 1970 the wafer size increased to 300 mm in 2000, enhancing the productivity of the chip manufacturing significantly. With growing diameters, wafer thickness of wafers increased steadily, reaching 775 μm for 300-mm diameter wafers. The primary reason for this increase was the need to ensure safe wafer manufacturing without breakage and to provide sufficient mechanical and thermal stability of the wafers in IC fabrication during processing steps of lithography and heat treatments. Beyond this, silicon wafers also must meet certain defect kinetic properties in device processing, which depend on the wafer thickness as well and are crucial for device yield and economic feasibility.