Figure 5 The LIGA process. Steps 1–5 are conventional lithography. Nickel is electroplated in step 6 after which the wafer is lapped to the desired thickness. Step 6 shows the remaining PMMA removed. The structures can then be freed from the seed metal base layer.

doi:10.1201/9780203910696-26

Chapter

Figure 5 The LIGA process. Steps 1–5 are conventional lithography. Nickel is electroplated in step 6 after which the wafer is lapped to the desired thickness. Step 6 shows the remaining PMMA removed. The structures can then be freed from the seed metal base layer.

Chapter

ABSTRACT

To overcome the limitation of synchrotron light source requirement, thick UV-sensitive resists, such as polyimides, AZ-4000, and SU-8, have been developed as alternatives to the x-ray-sensitive PMMA. Epon SU-8 is an epoxy-based, transparent negative photoresist material that can be built up into 200-µm-thick layers. Hoechst AZ-4000 is a positive resist material that can be built up into layers 15-80 µm thick with multiple spin coats. These materials and the technique certainly are more accessible than LIGA. Aspect ratios of 5:1 to 15:1 can be achieved with these materials.