Wafer Manufacturing

The wafer serves as the base upon which the integrated circuit is built. Wafers have been increasing in diameter over the decades as manufacturing technologies have improved. 150 mm wafers were typical until 1995, while 200 mm wafers became typical until early 2000 when 300 mm were developed. Today, 450 mm wafers are being developed. The rationale for larger wafers is that more individual integrated circuits can be built on a single wafer as the diameter increases. For instance, a 200 mm wafer has an area of 31,416 mm2 while a 300 mm wafer has an area of 70,686 mm2. Using the same processes, the output can essentially be doubled (2.25X) due to the increased area. Wafer processing involves multiple steps layer upon layer being built on the wafer. Each layer goes through the process of photolithography, baking, developing, etching and polishing and is interconnected at various places until the entire circuit becomes the integrated device.