메가소닉 교반에 의한 습식 식각 시스템 특성 개선
Performance Improvement of a Wet Etching System by Megasonic Agiation
- 주제(키워드) Wet Etching , Megasonic Agitation , Boundary Layer , etching characteristics , etching roughness
- 발행기관 아주대학교 대학원
- 지도교수 양상식
- 발행년도 2008
- 학위수여년월 2008. 8
- 학위명 박사
- 학과 및 전공 일반대학원 제어계측공학과
- 본문언어 영어
초록/요약
This dissertation presents performance improvement of a wet etching system by the megasonic agitation. For the fabrication of MEMS devices, it is essential that the etched surface of silicon or glass is smooth and defect-free with high dimensional uniformity. In this dissertation, we have proposed, designed and developed the wet etching system with the megasonic agitation for improving the characteristics of wet etching. The proposed wet etching system consists of etch bath module, circulation bath module, transfer module and control module. To adopt the megasonic energy into the wet etching, we have proposed the megasonic agitated module and accomplished the performance tests. To transfer the megasonic energy into the wafer without distortion effectively, the thickness of alumina for the megasonic agitated module (MAM) has been selected. The characteristics of the megasonic agiated module have been performed by measuring the impedance and the acoustic power. The proposed wet etching system has been designed and fabricated for improving the etching characteristics, namely, the etch uniformity, the etch rate, the surface roughness, and defect-free surface, by the megasonic agitation. At first, the characteristics of the wet etching system were evaluated by the anisotropic wet etching of (100) Si in KOH solution under various process conditions, namely the etching time, the megasonic power, and the temperature of the solution. In addition, the performance tests have been performed with the glass wafer and the (110) Si. Eventually, the megasonic energy from MAM improved the roughness and uniformity of the etched surface remarkably. Here, we suggests the best way to maintain the original surface roughness with MAM during the etching process. The results confirmed that the megasonic agitation is an effective way to improve the etching characteristics, such as the etch rate, etch uniformity and surface roughness, and that the wet etching system is suitable for the fabrication of devices with complex structures.
more목차
Chapter I. INTRODUCTION = 1
1.1 Motivation = 1
1.2 Review of the wet etching system = 4
1.3 Scope of Thesis = 11
Chapter II. THEORETICAL BASIS = 13
2.1 Fundamentals of Megasonic Wave for Wet Etching = 14
2.2 Boundary Layer of Megasonic Wave = 24
2.3 Removal Force by Megasonic Wave = 32
Chapter III. The DEVELOPED WET ETCHING SYSTEM = 36
3.1 Design of the Wet Etching System = 36
3.2 The Design of Megasonic Agitated Module (MAM) = 44
3.3 The Fabrication of Megasonic Agitated Module (MAM) = 49
3.3.1 The Selection of Thickness of an Alumina Plate for MAM = 49
3.3.2 The fabricated MAM and the performance test = 56
3.4 The Fabrication of the Wet Etching System = 69
Chapter IV. PERFORMANCE OF THE SYSTEM = 71
4.1 Sample Preparation = 71
4.2 The Influence of the Megasonic Agitation = 81
4.3 The Effect of Intensity of the Megasonic Agitation = 90
4.4 The relation with the Solution Temperature = 92
4.5 The Relation with the Variation of Etching Time = 96
Chapter V. OTHER APPLICATION OF THE SYSTEM = 97
5.1 Glass Wet etching = 98
5.2 (110) Si wafer Wet etching = 103
Chapter VI. CONCLUSION = 110
REFERNECES = 112
PUBLICATION LIST = 118
