Reactive Magnetron Sputtering에 의한 Boron Carbide 제조에 관한 연구 = (A) Study on Preparation of Boron Carbide Thin Films by Reactive Magnetron Sputtering

다국어 초록 (Multilingual Abstract)

It has been well known that applications of boron carbide(B_(4)C) are based on the combination of low specific density and extreme hardness, The material has also very high chemical and thermal stability. Boron carbide thin films have been prepared by different techniques: numerous publications refer to plasma-enhanced chemical vapor deposition (PECVD) using BCl_(3) or boranes as a source for boron and RF/DC magnetron sputtering using boron carbide target. In this work, the boron carbide thin films were characterized for mechanical properties such as hardness and adhesion.
Boron carbide thin films were prepared by reactive RF/DC magnetron sputtering. A 2-inch diameter target of sintered boron carbide was placed on the cathode. The target-substrate distance was 7cm and substrate holder was heated and rotated. The surface a one-side polished Si(100) wafer was thermally oxidized for substrate. The boron carbide thin films were deposited onto CoCr/Cr/SiO_(2)/Si. The base pressure of vacuum was held below 1.0×10^(-6) Torr. At that time, high purity Ar gas was introduced into the chamber through a mass flow controller to 3.6mTorr CoCr and Cr deposition were also carried out with the same conditions of 3.6mTorr, no substrate heating, RF power of 70W and deposition time of 30min. The deposition condition of boron carbide was as fellows, RF/DC power of 150W/100W, pre-sputtering time of 10min and deposition time of 50min. As another experiment boron target was used with applying RF powers of 25W, 50W and 75W. The substrate temperature were room temp., 100℃ and 200℃ and the reactive gas was introduced up to 1.6 vol% of (CH_(4)/(Ar+CH_(4))) ratio during deposition. This process, however was undesirable for preparation of boron carbide thin films because of coarse crystallite, porous microstructure and very low deposition rate. Surface morphology and cross-section was observed using field emisson scanning electron microscope(FE-SEM). Chemical bonding were examined by X-ray photo electron spectroscopy(XPS). Also, mechanical properties were measured using nanoindenter and scratch tester.
The size of boron carbide crystallites is about 100nm. An appearance of diffusion to layer by layer was found. In XPS analysis, two well-resolved peaks of C(1s) spectra were observed around 284eV, indicating C-C bond at 284.5eV and 8-C bond at 283.5eV. XRD analysis revealed that the boron carbide thin films were observed as a hybrid of crystalline and amorphous phases. AES composition of the thin films matched the gas ratios with B:C=73:24 in at% at CH_(4)/(Ar+CH_(4)) of 0.8%, substrate temperature of 100℃ and working pressure of 3.6mTor. The surface hardness and elastic modulus values reached up to about 23GPa and 250GPa, respectively. The scratched films endured the load of about 40N.

목차 (Table of Contents)

• 목차 = ⅰ
• Ⅰ. 서론 = 1
• Ⅱ. 이론적 배경 = 12
• Ⅱ -1 . 보론카바이드(B_(4)C)의 물성 = 12
• Ⅱ-2. Sputtring = 21
• Ⅱ-2-1. Sputtering 원리 = 21
• Ⅱ-2-2. Magnetron Sputtering = 22
• Ⅱ-2-3. Sputtering 과정 = 23
• Ⅲ. 실험방법 = 26
• Ⅲ-1. 박막의 제작 = 26
• Ⅲ-2. 박막의 특성 평가 = 29
• Ⅳ. 실험결과 및 고찰 = 30
• Ⅳ-1. B_(4)C target을 이용한 RF reactive magnetron sputtering 증착 실험 = 30
• Ⅳ-2. B_(4)C target을 이용한 DC reactive mgnetron sputtering 증착 실험 = 48
• Ⅳ-3. Boron target을 이용한 RF reactive magnetron sputtering 증착 실험 = 64
• Ⅴ. 결론 = 80
• Reference = 83
• Abstract = 85