Investigation on Thermal Stability of Metal-Interlayer-Semiconductor Contacts Using Carbon Implantation = 탄소 이온 주입 공정을 이용한 MIS contact의 열적 안정성 향상 연구

다국어 초록 (Multilingual Abstract)

Effects of carbon implantation (C-imp.) on the thermal stability of MIS (Metal-Interlayer-Semiconductor) contact were investigated. The experiment was conducted on both Si and Ge substrates. To improve the thermal stability in MIS contact, C-imp. into MIS structures was applied. The current density (J) - voltage (V) characteristics showed that C-imp. changed the rectifying behavior to the ohmic-like behavior. The Schottky barrier height (SBH) was also reduced by the C-imp. These improvements can be beneficial to reduce the lower contact resistivity (ρc) with the rapid thermal annealing (RTA) temperatures ranging from 450 to 600 ℃. From the transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) mapping, the MIS contact with C-imp. showed the suppression of oxygen diffusion into Ti layer. From the secondary ion mass spectrometry (SIMS) analysis, the segregation of P dopant at the interface was more facilitated with C-imp.. Thus, the C-imp. is promising to improve the thermal stability and to realize low contact resistivity of MIS contact.

목차 (Table of Contents)

• Abstract i
• Contents vii
• List of Figures viii
• List of Tables x
• I. Introduction 1
• 1.1 Technology node scaling of logic device 1
• 1.2 Characteristics and advantages of MIS contact 3
• 1.3 Thermal stability issue in MIS contact 5
• II. Measurement Methods 7
• 2.1 Multiring Circular Transmission Line Model (MR-CTLM) 7
• 2.2 Schottky Barrier Diode (SBD) 10
• 2.3 Process flow & Definition of MIS contact 12
• III. Results & Discussion 15
• 3.1 MIS contact on n-Si substrates 14
• 3.1.1 I-V characteristics of MIS contacts 14
• 3.1.2 J-V characteristics of Ti/TiO2/n-Si with Carbon implantaion 16
• 3.1.3 J-V and Φb characteristics of Ti/TiO2/n-Si at 600 ℃ 18
• 3.1.4 TEM analyses & EELS mapping of Ti/TiO2/n-Si at 600 ℃ 20
• 3.1.5 ρ_c & SIMS profiles of Ti/TiO2/n-Si : (i) w/o C-imp., (ii) CIT, (iii) CIS 22
• 3.2 MIS contact on n-Ge substrates 24
• 3.2.1 J-V curve and Φb characteristics of Ti/TiO2/n-Ge 24
• 3.2.2 TEM analyses of Ti/TiO2/n-Ge : (a) RTA 450 ℃, (b) RTA 600 ℃ 26
• 3.2.3 ρ_c characteristics of Ti/TiO2/n-Ge 27
• IV. Conclusion 28
• References 30
• List of Figures
• Fig. 1.1 Techonology node scaling of logic device from 90nm to 5nm 2
• Fig. 1.2 Rpara becomes a larger portion of Rtotal as the device scaling 2
• Fig. 1.3 Illustration depicting the contact area advantage in MIS contact over Silicide contact 3
• Fig. 1.4 Energy band diagrams of (a) M-S structure and (b) M-I-S structure 4
• Fig. 1.5 TEM of TiN/Ti/TiO2/n-Si (a) before and (b) after 500 °C RTP (c) O profile in TiN/Ti/TiO2 stack after RTP treatment 6
• Fig. 2.1 Multiring Circular Transmission Line Model structure (MR-CTLM) 7
• Fig. 2.2 Resistance extracted using MR-CTLM 8
• Fig. 2.3 Band diagram for MS junction 10
• Fig. 2.4 I-V curve for Φ_b extraction 11
• Fig. 2.5 Process flow of MIS contact formation 13
• Fig. 2.6 Structure of SBD and MR-CTLM 14
• Fig. 3.1 I-V characteristic of MIS (Ti/TiO2/n-Si) contact 15
• Fig. 3.2 J-V characteristics of CIT SBD after RTP treatment ranging from 450 to 600 ℃ 16
• Fig. 3.3 J-V characteristics of CIS SBD after RTP treatment ranging from 450 to 600 ℃ 17
• Fig. 3.4 J-V characteristics and of Ti/TiO2/n-si at 600 ℃. : without C-imp. (black) and with C-imp. (red,blue) 18
• Fig. 3.5 Φb characteristics of Ti/TiO2/n-si at 600 ℃. : without C-imp. (black) and with C-imp. (red,blue) 19
• Fig. 3.6 TEM images and EELS mapping for O, present in the Ti/TiO2/n-Si contacts without C-imp. : (a) before and (b) after RTA at 600 ℃ 20
• Fig. 3.7 TEM images and EELS mapping image for Ti, O present in the Ti/TiO2/n-Si contacts after RTA at 600 ℃ : (a) CIT (C-imp. Into TiO2) and (b) CIS (C-imp. Into Si) 21
• Fig. 3.8 ρc of the Ti/TiO2/n-Si contact after RTA ranging from 450℃ to 600 ℃ : w/o C-imp.(black), CIT(red), CIS (blue). 22
• Fig. 3.9 SIMS profiles for Ti/TiO2/n-Si contact after RTA at 600 ℃ 23
• Fig. 3.10 J-V characteristics of Ti/TiO2/n-Ge : (a) without C-imp. (b) with C-imp. after RTP process ranging from 450 to 600 ℃ 24
• Fig. 3.11 Φb of Ti/TiO2/n-Ge at 600 ℃. : w/o C-imp. (red) and w/ C-imp. (blue). 25
• Fig. 3.12 TEM images of Ti/TiO2/n-Ge contacts : (a) after RTA at 450 ℃ and (b) after RTA at 600 ℃ 26
• Fig. 3.13 ρc of the Ti/TiO2/n-Ge contact after RTA ranging from 450℃ to 600 ℃ : without C-imp. (blue), with C-imp. (red). 27
• List of Tables
• Table 2.1 Definition and Description of MIS contact 14