Multilayer pattern-definition processes

Polymer films that are sensitive to light, x-rays, or electrons— known as photoresists—are nsed extensively to transfer the pattern of an electronic circuit onto a semiconductor surface. Such films must adhere to the semiconductor surface, cross-link or decompose on exposure to radiation, and nndergo development in a solvent to achieve pattern definition. Virtually all aspects of photoresist processing involve surface and interfacial phenomena, and there are many outstanding problems where these phenomena mnst be controlled. For example, the fabrication of multilayer circuits requires that photoresist films of about 1-pm thickness be laid down over a semiconductor surface that has already been patterned in preceding steps. 

Test Pattern. The basic conductor properties can be measured using a single test pattern, as illustrated in Fig. 8.15. These include resistivity, print definition and film thickness, film density, solder leach resistance, wettability, adhesion, and wire bondability. Each property will be discussed individually with reference to Fig. 8.15. Many applications require functional use tests which usually require specific test patterns and even multilayer construction processes. Similarly, numerous applications require standard conductor tests on thick-fihn dielectrics instead of the bare substrate. 

---