wafer. The distance between stars is 100nm in this array. The pattern is shown on a

smaller scale in Figure 12.


















 Sample

 a) b) c)

Figure 12. The development of the pattern is shown in smaller scale. a) This is the
original star chosen from a menu in the Design CAD program. b) The program is
commanded to create an array of these stars, 20 stars in the x-direction and 20 stars in the
y-direction; shown is 2 stars in the x-direction and 2 stars in the y-direction. c) The
program is commanded to repeat this array to create the final pattern, 10 arrays in the x-
direction and 10 arrays in the y-direction; shown is 2 arrays in the x-direction and 2
arrays in the y-direction. Drawing not to scale of actual pattern.

This takes approximately two hours to complete. The areas exposed to the electron beam

must now be removed. The PMMA in the areas that are exposed to the electron beam

breaks down and can be easily removed once developed. The areas not exposed to

electron beam during patterning are not removed in the developing process. To remove

the exposed areas, the wafer is submerged in a 1 to 3 ratio of MIBK to isopropyl alcohol

developing solution for 70 seconds. Upon removal from the developing solution, the

wafer is rinsed in deionized water and dried by helium gas to prevent contamination from

particulates in the developing solution or deionized water. What is left is a layer of resist