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Correction of scanner errors using a capacitive sensor and phase compensation in White Light Phase Shifting Interferometry : 백색광 위상 천이 간섭계에서 정전센서와 위상 오차 보정 알고리즘을 이용한 스캐너 이송 오차 보정

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dc.contributor.advisor박희재-
dc.contributor.author권순양-
dc.date.accessioned2017-07-13T06:25:48Z-
dc.date.available2019-08-02-
dc.date.issued2016-08-
dc.identifier.other000000136091-
dc.identifier.urihttps://hdl.handle.net/10371/118543-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 8. 박희재.-
dc.description.abstractThe research in this dissertation aims at improvement of measurement results by correcting scanner errors in White Light Phase Shifting Interferometry (WLPSI). WLPSI is widely used to get surface profiles of inspection targets in Liquid Crystal Displays and semiconductor industries nowadays. WLPSI is a non-contact type inspection system, therefore it does not destruct target samples. WLPSI is one of the fastest measurement system, additionally it satisfies the measurement accuracy and repeatability. But, there always occurs phase errors due to irregular and non-linear scanner movement, and these factors affect the measurement stability.
There is a limitation to reduce movement errors of a vertical scanner by changing hardware. It is impossible to terminate mechanical delay of scanner movement due to inertia entirely. Errors caused by electrical delay cannot be avoidable either. In this thesis, a modified WLPSI system is suggested to correct phase errors without any changes in optics. It is very important not to make a complicated optics system and optical path, because it can make the lower measurement performance and cause the cost increases.
Compensated White light Scanning Interferometry (WSI) Peak and Modified Bucket Algorithm are proposed to compensate phase errors caused by irregular and non-linear scanner movement. By using the proposed system, the position of the vertical scanner can be directly acquired, and it is possible to correct phase errors by applying proposed methods with the acquired position data.
Different scan speed measurement and different scan start position measurement test are conducted to verify the proposed measurement system and algorithms. The measurement accuracy and the maximum difference between the results are under 0.4%. The measurement repeatability is also examined by 20 times repeat measurement for different measurement conditions. The target repeatability is 3σ 10 nm of the repeat measurement. The proposed method satisfies both the measurement accuracy and the measurement repeatability.
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dc.description.tableofcontentsChapter 1. Introduction 1
1.1. Research motivation 1
1.2. Trends of research 4
1.3. Research objectives and coverage 6

Chapter 2. Background Theory 8
2.1. Interferometry Principle 8
2.1.1. Michelson Interferometry 8
2.1.2. Interference Equation 11
2.2. Phase Shifting Interferometry 14
2.3. White Light Scanning Interferometry 17
2.4. White Light Phase Shifting Interferometry 22

Chapter 3. Detection of phase error 24
3.1. Definition of phase error 24
3.2. Causes of Phase error 27
3.3. Reference phase error by non-linear movement of PZT 28
3.3.1. Detection of phase errors by analyzing images 32
3.3.2. Analysis for relative phase error and the scanner movement 34
3.4. WSI analysis error by inertia 37
3.5. Previous researches to detect and correct the phase errors 41
3.5.1. Additional interferometry 41
3.5.2. Self image set correction 44
3.5.3. Signal input shaping 46

Chapter 4. Analysis of the scanner movement 48
4.1. Electrical analysis 48
4.2. Mechanical analysis 52

Chapter 5. Real time phase error compensation by using capacitive sensor 57
5.1. Conventional WLPSI system 58
5.2. WLSPI with the real time scanner movement detection system 60
5.3. Compensation method 64
5.3.1. Compensated WSI Peak 65
5.3.2. Modified Bucket Algorithm 68
5.4. Evaluation of the proposed method 78
5.4.1. Unequivalent movement of the scanner simulation 78
5.4.2. Non-linear scanner movement simulation 84

Chapter 6. Experimental Setup 89
6.1. Entire system diagram 89
6.2. Configuration of optics 91
6.2.1. LED light source 91
6.2.2. Band pass filter 92
6.2.3. CCD Camera 93
6.2.4. Objective Lens 95
6.2.5. PZT Scanner 96
6.2.6. Capacitive sensor 97
6.2.7. Vibration isolating system 98

Chapter 7. Experimental Result 101
7.1. Scan speed change test 103
7.2. Different scan position test 109

Chapter 8. Conclusion 118

REFERENCES 120

APPENDIX 126
A. Experiment data by using another scanner 126
A.1. Scan speed change test 127
A.2. Different scan position test 131

ABSTRACT IN KOREAN 137
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dc.formatapplication/pdf-
dc.format.extent3926047 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectWhite Light Phase Shifting Interferometry-
dc.subjectModified Bucket Algorithm-
dc.subjectCompensated WSI Peak-
dc.subjectCapacitive sensor-
dc.subjectPhase error compensation-
dc.subject.ddc621-
dc.titleCorrection of scanner errors using a capacitive sensor and phase compensation in White Light Phase Shifting Interferometry-
dc.title.alternative백색광 위상 천이 간섭계에서 정전센서와 위상 오차 보정 알고리즘을 이용한 스캐너 이송 오차 보정-
dc.typeThesis-
dc.description.degreeDoctor-
dc.citation.pages138-
dc.contributor.affiliation공과대학 기계항공공학부-
dc.date.awarded2016-08-
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