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Influence of Pulsed Substrate Bias Voltage on the Properties of Sputtered Thin Films

  • Hye Won Seok (석혜원, 대학원 전기전자전파공학과 전자전기컴퓨터공학전공)

초록/요약

The effect of substrate bias on the crystal growth, crystal orientation, and electrical properties etc. of RF magnetron sputtered conductive material -Titanium nitride (TiN), insulative material -Aluminum nitride (AlN) and semiconductive material - Strontium copper oxide (SrCu2O2) thin films have been studied. At first, TiNx thin films have been fabricated by RF reactive sputtering with pulsing DC bias to substrate at 350 kHz during the film deposition. The electrical properties of the resultant metallic TiNx thin film such as electrical conductivity, carrier mobility and concentration were significantly increased by pulsing DC substrate bias. XRD and SEM showed the improvement in the crystallinity and grain size of TiNx thin film. And XPS analysis revealed that the oxygen content incorporated into the TiNx film was significantly decreased by the pulsing the negative DC bias voltage to the substrate. Secondary, negative DC bias voltage with 350-kHz pulse frequency was applied to substrates during deposition of AlN thin films by reactive RF magnetron sputtering at RT. The crystallite size of the AlN thin films was significantly increased from about 10 nm to 100 nm by the pulsed substrate bias of -50 V. XPS clearly showed the concentration of Al-O bond was greatly decreased to under half, and the ratio of Al and N concentration was adjusted to 1:1 approximately. The electrical resistivity and thermal conductivity of AlN thin films was extremely improved as 6.3×1010 Ω∙cm, 168 W/mK with the pulsed substrate bias. Third, transparent p-type semiconducting SrCu2O2 films have been deposited by RF magnetron sputtering under unbalanced bipolar pulsed DC bias on low-alkali glass substrates in a mixed gas of 1 % H2/Ar below 400 oC. The pulsed DC bias voltages to substrate were varied from 0 V to -200 V. The deposition rates of SrCu2O2 films under DC-pulsed bias show a maximum at -100 V bias, and decreased with increasing the bias voltage. XRD results of the as-deposited films under the bias voltage at 300 oC reveal SrCu2O2 polycrystalline phase, and increased crystallite size with increasing pulsed DC bias voltage. The SrCu2O2 films deposited under the pulsed-bias of -100V at 400 oC exhibits the highest conductivity of 0.08 S/cm, and over 70% of transmittance at 550 nm. It is confirmed that the application of pulsed DC bias in sputtering improves the crystallization, crystal growth, and the electrical and optical properties eventually under 400 oC. Finally, Transparent p-n heterojunction diodes based on oxide semiconductors were fabricated by RF magnetron sputtering on alkali-free glass substrates. 3% Al-doped ZnO(AZO) was deposited as an n-type component, and SrCu2O2 as a p-type component. Sn-doped In2O3(ITO) and 7% V-doped Ni metal were deposited as n- and p-type electrodes at room temperature, respectively. The as-deposited p-n heterojunction diode showed very high transparency of about 69% at 550nm. I-V measurement of the multilayered transparent p-n heterojunction diode exhibited rectifying characteristics. This research helped to understand the process conditions for RF sputtering with substrate biasing and its influence on various thin film properties.

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목차

ABSTRACT
CHAPTER 1. INTRODUCTION
1. 1. Introduction
1. 2. Structure Zone Model in Polycrystalline Thin Films
1. 3. Process Technology
1. 3. 1. Magnetron Sputtering
1. 3. 2. Bias sputtering
1. 3. 3. Pulsed DC bias sputtering
CHAPTER 2. PROCESS TECHNOLOGY AND MATERIALS
2. 1. Process Technology - Pulsed DC substrate bias assisted RF magnetron sputtering system
2. 2. Materials
2. 2. 1. Titanium Nitride
2. 2. 2. Aluminum Nitride
2. 2. 2. Strontium Copper Oxide
CHAPTER 3. INFLUENCE OF TITANIUM NITRIDE THINFILMS DEPOSITED BY DC BIAS VOLTAGE WITH 350KHZ PULSE APPLIED RF SPUTEER
3. 1. Introduction
3. 2. Experimental
3. 3. Results and Discussion
3. 4. Summary
CHAPTER 4. PULSED DC SUBSTRATE BIAS EFFECT ON ALN THIN FILMS DEPOSITED BY RF MAGNETRON SPUTTERING
4. 1. Introduction
4. 2. Experimental
4. 3. Results and Discussion
4. 4. Summary
CHAPTER 5. PULSED DC BIAS EFFECT ON P-TYPE SEMICONDUCTOR SRCU2O2 FILM
5. 1. Introduction
5. 2. Experimental
5. 3. Results and Discussions
5. 4. Summary
CHAPTER 6. FABRICATION OF TRANSPARENT P-N JUNCTION DIODE BASED ON OXIDE SEMICONDUCTORS DEPOSITED BY RF MAGNETRON SPUTTERING
6. 1. Introduction
6. 2. Experimental
6. 3. Results and Discussions
6. 4. Summary
CHAPTER 7. CONCLUSION
LIST OF REFERENCES
LIST OF PUBLICATIONS
International Journals (SCI papers)
Domestic Journals (KCI papers)
International Conferences
Domestic Conferences
Award
Patents
ABSTRACT (KOREAN)
ACKNOWLEDGEMENT (KOREAN)

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