Development of a self-alignment process between the SIL/SSIL and aperture for near-field recording pick-up head

• Main Authors: Yu-Ru Chang, 張育儒
• Other Authors: Wensyang Hsu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/62g9x5

碩士 === 國立交通大學 === 機械工程系所 === 94 === Owing to the conventional optical pick-up head has diffraction limit in data storage. In order to overcome the diffraction limit, the research focuses on the optical data storage system by near-field recording (NFR). In NFR pick-up head, the SIL/SSIL and aperture are key components to overcome the diffraction limit. According to the previous research, combining the SIL/SSIL and aperture together in NFR pick-up head can obtain better optical resolution and performance. But the misalignment between the SIL/SSIL and aperture always occurred in assembling or bonding step. Hence the research here brings up the self-alignment technique to overcome the misalignment problem. The glass substrate is chosen for self-alignment technique, which is based on the backside exposure. By backside exposure step, the SIL/SSIL and aperture will be aligned precisely. Furthermore, a new integration structure of NFR pick-up head combining SIL, aperture, and microcoil is proposed. The fabrication process is based on Micro Electro Mechanical System (MEMS) and UV-LIGA technologies. This fabrication process is a batch process without assembling or bonding step. Comparing with the conventional fabrication process, the low cost and easy process step can be obtained in this process. The aperture of diameter 2.88μm is made easily in NFR pick-up head. Owing to the shrinkage aperture step has some trouble, so the initial aperture can not shrink to nano scale. The fabrication results of SIL compared with designed values, the deviation in sag height of SIL is less than 2%, but it is about 6% in radius of SIL. Owing to the surface profile of SIL component is not a perfect hemisphere after thermal reflowing process, but the designed of SIL is assumed a perfect hemisphere. Hence we will obtain a larger deviation in radius size of SIL. The microcoil and contact pad structure with large thickness can be made with low stress by controlling the electroplating recipes. In this research, the self-alignment technique is verified a feasible process. The measuring results of spot size compared with simulation results, we found that the deviation is 4~10%. The SIL of diameter 60μm and 70μm has 30.1% and 29.1% shrinkage efficiency, respectively. The SIL that has sag height 30μm has 50% transmission efficiency. Finally, the reliability of SIL is tested by laser that has light intensity 6mW/cm2. The spot size calibration before and after laser destruction is conformably. Furthermore, the surface of SIL is not damaged completely.