Bit patterned media (BPM) is expected to enable the magnetic storage density in hard disk drives (HDDs) beyond 1 Tb/in2. BPM uses isolated magnetic islands to record the data information. However, the large volume fabrication of those patterned media disks at an affordable cost is a challenge for this new technology. A master template is the first step for patterned media fabrication. Using nano-imprint technology, the master template can be replicated to tens of thousands of pattern disks. A rotary electron beam lithography machine or plasmonic nanolithography machine is recommended to assist in the fabrication of the master template. In both systems, a high resolution encoder system for positioning in the rotary lithography machine is necessary. In this paper, a magnetic rotary encoder system is introduced. The encoder system can be operated at several thousand revolution per minute (RPM). The scale pitch is 90 nm which is one to two orders smaller than current optical encoders. The resolution is about 2.8 million counts per revolution (CPR). A flying magnetic head is used to retrieve the readback signal from the magnetic encoders. A field programmable gate array (FPGA) is implemented to finish the high speed signal processing and provide a digital format encoder signal to trigger the lithography machine at a rate of several Mega Hertz.
- Information Storage and Processing Systems Division
A Magnetic Rotary Encoder for Patterned Media Lithography
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Xiong, S, Wang, Y, Zhang, X, & Bogy, D. "A Magnetic Rotary Encoder for Patterned Media Lithography." Proceedings of the ASME 2014 Conference on Information Storage and Processing Systems. 2014 Conference on Information Storage and Processing Systems. Santa Clara, California, USA. June 23–24, 2014. V001T06A001. ASME. https://doi.org/10.1115/ISPS2014-6910
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