ABSTRACT
Monocrystalline 4H-SiC Wafer ........................................................ 138 9.2 ELID Polishing and Grinding of Magnetic Heads ....................................... 142
9.2.1 Introduction ...................................................................................... 142 9.2.2 Experimental Setup .......................................................................... 142 9.2.3 ELID Parameters .............................................................................. 150
9.2.3.1 Grain Size or Mesh Number of the Wheel ........................ 150 9.2.3.2 Truing Time ....................................................................... 151 9.2.3.3 Cutting Speed..................................................................... 151 9.2.3.4 Grinding Force ................................................................... 151 9.2.3.5 Wheel Resistivity ............................................................... 154 9.2.3.6 Wheel Material .................................................................. 154
9.2.4 Results and Discussions .................................................................... 155 9.2.4.1 ELID Polishing Results ..................................................... 155 9.2.4.2 Statistical Analysis of the Results ...................................... 160
9.3 Molds ............................................................................................................ 162 9.4 Microtools ..................................................................................................... 164
9.4.1 Introduction ...................................................................................... 164 9.4.2 Fabrication of Microtools by ELID Grinding .................................. 168 9.4.3 Generation of Microtools with High-Quality Surfaces .................... 172 9.4.4 Development of a New Desktop Microtool Machining System ....... 175 9.4.5 Examples of Microtools Fabricated by ELID Grinding ................... 181
9.5 Optics Finishing Integrating ELID Grinding and MRF .............................. 181 9.5.1 Introduction ...................................................................................... 185
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used to fabricate integrated circuits and other microdevices. Electrolytic in-process dressing (ELID) grinding technology is suitable for achieving mirror-quality surface ‘nishing of silicon wafers. Figure 9.1 shows a basic ELID rotary grinding system with a cup-type grinding wheel. Figure 9.2 shows an image of the grinding wheel surface after stable grinding. The white regions in the image are the ‘ne diamond abrasives (3 µm). The wheel surface is covered with an insulating layer. Figure 9.3 shows the obtained surface roughness. A surface roughness of 20 nm in Rz was achieved using a #4000 grinding wheel. Figure 9.4 shows an example of subsurface damage. It is possible to reduce the amount of subsurface damage (less than 0.4 µm) using a #8000 grinding wheel. A higher quality surface is generally obtained using a ‘ner grinding wheel. Figure 9.5a shows an image of a ‘nished silicon wafer and Figure 9.5b shows its surface ˜atness.
