Effect of Deposition Temperature in Cubic Boron Nitride Thin Film Deposition
- 주제(키워드) cubic boron nitride (c-BN) , temperature , unbalanced magnetron sputtering (UBM) , nanocrystalline diamond (NCD)
- 발행기관 고려대학교 대학원
- 지도교수 성태연
- 발행년도 2013
- 학위수여년월 2013. 8
- 학위구분 석사
- 학과 일반대학원 신소재공학과
- 원문페이지 104 p
- 실제URI http://www.dcollection.net/handler/korea/000000046468
- 본문언어 영어
- 제출원본 000045764538
초록/요약
With the advancement of industrial technology, it is noted that surface thin-film technology to improve the surface properties of any parts for higher value-added in an in high technology industries. The reduction of life cycle due to wear and corrosion of mold or tools used in industrial site currently reduces productivity and is directly connected to ecomomic losses. To solve this problem, development of thin-film technology has been carried out to improve the characteristics by coating an ultra hard protective film for mold or tools. c-BN has extreme hardness about 70~90 GPa which is only exceeded by diamond, is possible to be deposited at low temperatures unlike diamond and resistant to oxidation, therefore, c-BN is drawing attention as protective coating materials and cutting tools. Especially, unlike diamond, c-BN is inert to ferrous-based metals and suitable for use in materials as coatings and cutting tools for ferrous-based materials. Besides c-BN has wide band gap energy (Eg~6eV) and a high thermal conductivity, so it can be applied to high temperature and high power electronic materials. It is also applicable to optical protective coatings since it is transparent in infrared and visible light region. In addition, it has been successfully doped, both p-type and n-type with a promising potential as semiconductor. Synthesis of c-BN films is possible through methods such as IBAD (Ion beam assisted deposition), RF magnetron sputtering, mass selected IBAD, bias assisted CVD, PACVD (Plasma assisted CVD). However, in order to synthesize BN on cubic, ion bombardment with certain energy to thin film during deposition is required. Except IBAD, most of the deposition methods are induced ion bombardment by applying a negative bias voltage. The industrial applications are not made despite the excellent properties of the c-BN film. It can be caused by limitation to synthetic films with high adhesion due to high compressive residual stress and low adhesion that entails necessarily, and the crystal size of c-BN film is small (<20nm) by ion bombardment effect necessary for the formation of c-BN[9]. Therefore, improving adhesion with the basic material must be solved urgently to apply c-BN films currently. There are two major reasons of the low adhesion strength of BN films. First, ion Bombardment of constant energy is required for forming BN films on cubic and this causes a residual stress of the substrate. Another reason for detachment is a hygroscopic property of BN. It is due to microstructural properties of BN films. BN films have low stability in the atmosphere to induce detachment by forming a B2O3, 40% more than BN in volume through reacting with moisture [14]. The c-BN is affected by variables such as ion energy, ion to neutral atom flux ratio, deposition temperature. Among the theses published to date, the report of the results corresponding to the deposition temperature do not match for each of them. There is reported to be excellent adhesion as the deposition temperature increases [25], but also reported lower adhesion [26]. Besides, there is a lack of the consistency on the behavior of thin films such as c-BN contents [24-27], synthesis temperature range. Therefore, it is shown to be necessary to systematic observations on the effect of deposition temperature. In this thesis, the effect of deposition temperature in the synthesis of c-BN film is investigated using UBM system (unbalanced magnetron sputtering) mainly used in mass production. In addition, the relationship between substrate temperature and atmospheric stability is analyzed through the behavior of thin films.
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TABLE OF CONTENTS
TABLE OF CONTENTS I
LIST OF FIGURES IV
LIST OF TABLES VII
1. Introduction 1
2. Literature Survey
2.1 Review of Boron Nitride(BN) Material 4
2.1.1 Structure of BN 4
2.1.2 Properties of BN 7
2.1.3 Phase Diagram of BN 10
2.2. Synthesis of cubic BN(c-BN) 13
2.2.2 Vapor Deposition 13
2.2.2.1 Chemical Vapor Deposition 14
2.2.2.2 Physical Vapor Deposition 14
2.3. Deposition Behavior of c-BN 15
2.3.1 Microstructure of c-BN 15
2.3.2 Experimental Parameters in c-BN Deposition 18
2.4 Problem of c-BN Film 25
2.4.1 Residual Stress 27
2.4.2 Stability under Atmospheric 28
2.5 Purpose of This Work 30
3. Experiment
3.1 Deposition Equipment 32
3.2 Preparation of Nano-Crystalline Diamond(NCD) Buffer Layer 36
3.3 Deposition of c-BN Thin Film 40
3.3.1 Experiment of Substrate Temperature 40
3.3.2 Experiment of Moisture Desorption 41
3.4 Analysis of c-BN Film 42
3.4.1 Analysis of Phases in BN Film 42
3.4.2 Analysis of Microstructure of BN Film 45
3.4.3 Analysis of Stress of BN Film 46
3.4.3.1 Principle of Stress Measurement 49
4. Results
4.1 Effect of Absorbants on Chamber wall on c-BN Deposition 54
4.1.1 Deposition of c-BN films according to Exhaustion Time 55
4.1.2 Deposition of c-BN films according to Chamber Baking 57
4.1.3 Deposition of c-BN films according to Plasma Treatment 60
4.2 Deposition Behavior of BN films according to Deposition Temperature
4.2.1 Atmospheric Stability 62
4.2.2 Parameter Space of BN Film 64
4.2.3 Thickness Variation of BN Film 67
4.2.4 Variation of c-BN Contents and Residual Stress of BN Film 69
4.2.5 Variation of Behavior of Alignment on h-BN Layer 73
4.2.6 Crystallinity Change Behavior of h-BN Layer 80
4.3 Moisture Reaction of h-BN Layer 82
5. Summary and conclusion 86
6 References
