Overall Process Description. The manufacturing process utilizes chemicals to convert a silicon wafer into a multi-layer semiconductor device. Figure 1, found in Attachment C, schematically depicts the basic process flow and chemical usage of the semiconductor manufacturing process. The general process, which repeats itself five to fifteen times depending on the complexity of the semiconductor device, is as follows. The surface of a silicon wafer is cleaned and passivated with the production of a very thin silicon oxide layer. An organic photoresist is applied to the wafer and a circuit pattern is exposed onto the resist by shining light onto the wafer through a mask. The exposed photoresist is washed away, while the remainder is hardened to protect the insulating layer. After this is completed, the wafer is treated with inorganic liquids and gases to create the doped circuits which provide the semiconductor function. The hardened resist is then ashed or removed with organic solvents. At certain points in the process, metallization techniques are used to electronically connect the stacked layers of the semiconductor device. Wafer cleaning and rinsing steps, using mixtures of inorganic acids, oxidizers, and deionized water, occur after many of the process steps. This process cycle is repeated until a fully functional memory or logic device has been produced. After the circuits are built on the wafer, minute amounts of metal are deposited onto the wafer to produce the connections which will marry the semiconductor to a module or circuit board for use in a computer. Finally, the wafer is sliced into individual chips for test and placement onto substrates or modules for use in computer systems.
