Integrated circuits etching processes

Etching. After a resist is patterned on a wafer, the exposed or unwanted substrate is removed by etching processes. Subsequentiy the resist is removed, leaving a desired pattern in a functional layer of the integrated circuit. Etching is performed to pattern a number of materials in the IC fabrication process, including blanket polysiHcon, metal layers, and oxide and nitride layers. The etch process for each material is different, and adapted to the material requirements of the substrate. 

According to the international technology roadmap for semiconductors, chips with a wafer diameter of450 mm and a feature size of 0.05 /xm by 2011 will serve to decrease manufacturing costs [29]. In the integrated circuit (IC) manufacture process as shown in Fig. 21 [30], dielectric stacks have been formed by the ion etching on the coating of dielectric material formed on the silicon surface (Fig. 21 (a)). 

Photo-resist technology is widely used for imaging processes in such applications in electronics. If it is wished to produce a metallic pattern of connections between many electronic components (resistors, capacitors, integrated circuits, etc.), this can be done by the selective etching of a thin copper plate deposited on an insulating base. The copper layer is protected by a resist which is a polymer, deposited in such a way that it prevents the attack of the metal by an etching solution which will solubilize only the unprotected, exposed copper (Figure 6.8). 

Most companies producing ICs today have been quite lax in the quality control of the liquid chemicals used in their processes. These chemicals include acids, bases, buffered etches, photoresists, and organic solvents. Essentially, the producers of ICs have left the quality control of these materials to the chemical manufacturers. Specifications for chemicals are set by SEMI (Semiconductor Equipment Manufacturers International) and are generally met by all chemical manufacturers. The level of metallic contaminations that can exist in U.S. chemicals ranges from 0.1 to 1 ppm. If the levels of metallic impurities were actually this high, U.S. manufacturers would not be able to produce integrated circuits. 

---