| Popis: |
Recent market trends have shown a steady growth in the demand for storage devices. This demand has been fueled by a number of reasons; primarily among them are the e-commerce explosion and the availability of advanced digital media at home and business. However, the cost of storage has shown an opposite trend. It is estimated that the cost of disk storage drops at a rate of 1% per week, partly because manufactures have to cater to the sub $1000 PC market. In such a competitive market, reducing cycle time for manufacturing of heads and enhancing the yield becomes very critical. Broadly, head manufacturing process can be classified into three main areas Wafer Fabrication Slider Fabrication Head Gimbal Assembly (HGA). The approximate processing time in the wafer fabrication is 6 weeks, two weeks in the slider fabrication and about a week in the final assembly. The cost of a head at the slider fab is double than that at wafer level and increases four fold by the time it reaches the final assembly. Thus for a manufacturer to remain competitive, advanced process control at every step is critical. This helps in reducing the amount of scrap and thus reduces production costs. At the wafer level, top down CD SEMs have long been used for monitoring critical dimensions. These SEMs have kept ahead of the technology curve as current Thin Film Head (TFH) processes for manufacture of heads have resulted in sub 0.1-micron dimensions. A consequence of these advances in processes is that optical tools, which were traditionally used for metrology at the slider level, have reached their physical limit and these fabs have started using CD SEMs for metrology. |
