本研究針對利用近場光學突破繞射極限的光儲存系統:近場光學磁光(Magneto-Optic；以下簡稱MO)讀取頭進行相關研究，利用微機電技術提出一整合製程。此MO讀取頭包含:(1) 空氣軸承(air bearing)；(2) 微電磁線圈；(3) 奈米微孔；(4) 超半球固態浸沒式透鏡(Supersphere Solid Immersion Lens；以下簡稱SSIL)。本研究所提出之新式製程可批次生產，與傳統方法比較，元件不需組裝利於微小化，可批次量產；大幅簡化生產流程。研究並針對SSIL提出一新式而簡易的製程。
對製作之MO讀取頭進行出光測試，利用本研究室以往提出之電鍍法製作微孔；孔徑可縮至340奈米，並可進一步縮小。量測穿過孔徑為500奈米之出光光點大小，量測到之光點大小約為750~800奈米，這是由於可供操作之設備僅可量測遠場光點，量測結果為略經發散過的光點。觀察利用新式製程製作之SSIL，與設計值作比較，尺寸上最大誤差值少於2.4%。SSIL此時折射率為1.66。而利用UV-LIGA技術製作微金屬線圈。並製作出金屬內連線供電流輸入。最後利用厚膜之熱固性光阻SU-8強化整個元件結構。

The research focuses on the optical data storage system by near field recording that can break through the diffraction limit. The MO (Magneto-Optic) pickup head is studied and fabricated by MEMS(MicroElectroMechanical System)technology. The MO pickup head combines (1) air bearing, (2) microcoils, (3) nano-aperture, (4) Supersphere Solid Immersion Lens (SSIL). The proposed process is a batch process and does not need assembly to achieve a MO pick up head combining SSIL, nano aperture, air bearing and magnetic coils for high-density data storage. And a new process is also proposed to fabricate the SSIL.
The spot size is measured to verify the process is feasible. The nano-aperture about 340 nm is fabricated by the “electroplating method”. The Full Width Half Maximum (FWHM) spot size is about 750 nm to 800 nm after the focused incident light passing through the nano-aperture about 500 nm. This is due to the available measured equipment is far filed detection. The dimensions of the SSIL is observed and compared with the designed values, the maximum errors occur in dimensions is less than 2.4% and the refraction index of the SSIL is about 1.66 at this time. The microcoils and interconnection lines are fabricated by UV-LIGA technology. The SU-8 is chosen to strengthen the pickup head.

Table of Contents
摘 要 i
Abstract ii
誌 謝 iii
Table of Contents iv
List of Figures…………………………………………………………………………v
List of Tables………………………………………………………………………….vi
Chapter 1 1
Introduction 1
1.1 Motivation 1
1.2 Related Researches 1
1.2.1 Near-field Recording 2
1.2.2 MO (Magneto-Optic) structure 11
1.2.3 Air bearing in the pickup head 13
1.3 Current Approach 16
Chapter 2 17
Design 17
2.1 Concept Design 17
2.2 Designs of the individual parts 17
2.2.1 Air bearing Design 17
2.2.2 Sub-micron aperture Design 18
2.2.3 Microcoils Design 19
2.2.4 SSIL (Supersphere Solid Immersion Lens) Design 21
Chapter 3 27
Fabrication 27
3.1 Fabrication process 27
3.2 Process of the air bearing fabrication 29
3.3 Process of the Sub-Micrometer aperture fabrication 30
3.4 Electroplating microcoils 30
3.4.1 Thick film process 31
3.4.2 Electroplating process 33
3.5 Interconnection 34
3.6 Process of the Supersphere Solid immersion lens (SSIL) fabrication 35
Chapter 4 37
Results and discussion 37
4.1 Aperture 37
4.2. SSIL 38
4.3. microcoil 41
Chapter 5 44
Conclusion 44
5.1 Conclusion 44
Reference 45
List of the Figures
Fig. 1.1 chart of a light focused by an objective lens 2
Fig. 1.2 Optical data storage structure with solid immersion lens 3
Fig. 1.3 Fabrication process of microlens 4
Fig. 1.4 Fabrication of the micro-SIL by press molding 4
Fig. 1.5 Schemes of microlens arrays fabrication 5
Fig. 1.6 Geometry of the SSIL structure 6
Fig. 1.7 Chemical etched optical fiber tip 6
Fig. 1.8 Expose by using the evanescent wave 7
Fig. 1.9 Use FIB to etch the metal film to make an aperture 7
Fig. 1.10 Make a hole by chemical etching 8
Fig. 1.11 Make a sub-wavelength aperture by over-electroplating 9
Fig. 1.12 Fabrication process for aperture array combined with SIL 9
Fig. 1.13 Batch fabrication process combining aperture and SIL 10
Fig. 1.14 Flying head with Objective lens and SIL 12
Fig. 1.15 MO tester with SIL 13
Fig. 1.16 Linear velocity dependence of flying height of SIL 13
Fig. 1.17 the SNOM probe with sliders 14
Fig. 1.18 air bearing design and pressure distribution at the bottom of the pickup head 14
Fig. 1.19 air bearing designs 15
Fig. 1.20 air bearing design 15
Fig. 2.1 Schematic diagram of the MO pickup head design 17
Fig. 2.2 (a) Initial aperture size defined in a pedestal (b) Aperture size after shrinking with metal deposited 19
Fig. 2.3 Simulation model (a) Top view (b) side view 20
Fig. 2.4 (a) Maximum temperature of the “Microcoil A” with different applied voltage 21
(b) Maximum temperature of the “Microcoil B” with different applied voltage 21
Fig. 2.5 (a) Light path of the SSIL (b) “NAIL” structure 22
Fig. 2.6. Absorption versus thickness of the AZ-P4620 23
Fig. 2.7 The SSIL can be divided into two different parts to be designed 24
Fig. 2.8 Minimum microlens shape (Sag) of the SSIL 25
Fig. 3.1 “Edge bead” effect after coating thick film photoresist 32
Fig. 3.2 Second electrode connect to each microcois for electroplating interconnection lines 35
Fig. 4.1 Aperture size after shrinking by electroplating is (a) 860μm (b) 635μm (c) 338μm separately with the different electroplating time 37
Fig. 4.2 (a) the radiant after passing through a 500 nm aperture (b) the FWHM of the spot size shown in (a) 38
Fig. 4.3 The single layer photoresist film AZ-P4620 is patterned with different dimensions by the multi-exposure method 39
Fig. 4.4 (a) photoresist structure before reflow (b) result of the photoresist structure shown in (a) after reflow 40
Fig. 4.5 (a) photoresist structure before reflow (b) result of the photoresist structure shown in (a) after reflow 40
Fig. 4.6 The profile and dimensions of the fabricated SSIL structure 41
Fig. 4.7 (a) Microcoil structures with air bearing observed by O.M. (Optical Microscope) (b) SEM of the microcoil structures 42
Fig. 4.8 (a) The disconnection microcoil structures (b) Rugged profile due to the air bearing structures 43
Fig. 4.9 Interconnection lines for input signal 43
List of the Tables
Table 2.1: Sizes of the different microcoils…………………………………………..20
Table 3-1 Process flow chart…………………………………………………………27
Table 3-2 Basic recipes of coating AZ-P4620 40μm…………………………………31
Table 4-1 Experiment results compared with the designed value in SSIL dimensions……………………………………………………………………………41

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