• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.127-134
• /
• 2001

Nano adhesion and friction between a Sj$_3$N$_4$ AFM tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes in various ranges of normal load. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and Si-wafer of different surface roughness were used. Results showed that nano adhesion and friction decreased as the surface roughness increased. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the normal load was low.

• ETRI Journal
• /
• v.31 no.6
• /
• pp.675-679
• /
• 2009

$Ti_xSi_{1-x}O_y$ (TSO) thin films are fabricated using plasma-enhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub-cycle ratio of $TiO_2$ and $SiO_2$. The refractive indices of $SiO_2$ and $TiO_2$ are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current-voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films.

• Tribology and Lubricants
• /
• v.17 no.4
• /
• pp.276-282
• /
• 2001

Nano adhesion between SPM (scanning probe microscope) tips and 075 (octadecyltrichlorosilane) SAM (self-assembled monolayer) was experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM(atomic force microscope) and LFM(lateral force microscope) modes in various conditions of relative humidity. OTS SAM was formed on Si-wafer (100) surfaces, and Si$_3$N$_4$ tips of different radius of curvature were used. When the surface was hydrophobic, the adhesion and friction forces were found lower than those of bare Si-wafer. Results also showed that micro-adhesion force increased as the relative humidity and the tip radius of curvature increased. The main parameter for affecting the micro-adhesion was found absorbed humidity on the contact surface. These results were discussed with the JKR model and a capillary force caused by absorbed water.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.8
• /
• pp.657-662
• /
• 2003

This paper presents a new fabrication method of selective SiGe epitaxial growth at 650 $^{\circ}C$ on (100) silicon wafer with oxide patterns by reduced pressure chemical vapor deposition. The new method is characterized by a cyclic process, which is composed of two parts: initially, selective SiGe epitaxy layer is grown on exposed bare silicon during a short incubation time by SiH$_4$/GeH$_4$/HCl/H$_2$system and followed etching step is achieved to remove the SiGe nuclei on oxide by HCl/H$_2$system without source gas flow. As a result, we noted that the addition of HCl serves not only to reduce the growth rate on bare Si, but also to suppress the nucleation on SiO$_2$. In addition, we confirmed that the incubation period is regenerated after etching step, so it is possible to grow thick SiGe epitaxial layer sustaining the selectivity. The effect of the addition of HCl and dopants incorporation was investigated.

• Journal of the Korean Applied Science and Technology
• /
• v.16 no.1
• /
• pp.33-40
• /
• 1999

We used Cu as a representative of metals to be directly adsorbed on the bare Si surface and studied its removal DHF, DHF-$H_2O_2$ and BHF solution. It has been found that Cu ion in DHF adheres on every Si wafer surface that we used in our study (n, p, n+, p+) especially on the n+-Si surface. The DHF-$H_2O_2$ solution is found to be effective in removing metals featuring high electronegativity such as Cu from the p-Si and n-Si wafers. Even when the DHF-$H_2O_2$ solution has Cu ions at the concentration of 1ppm, the solution is found effective in cleaning the wafer. In the case the n+-Si and p+-Si wafers, however, their surfaces get contaminated with Cu When Cu ion of 10ppb remains in the DHF-$H_2O_2$ solution. When BHF is used, Cu in BHF is more likely to contaminate the n+-Si wafer. It is also revealed that the surfactant added to BHF improve wettability onto p-Si, n-Si and p+-Si wafer surface. This effect of the surfactant, however, is not observed on the n+-Si wafer and is increased when it is immersed in the DHF-$H_2O_2$ solution for 10min. The rate of the metallic contamination on the n+-Si wafer is found to be much higher than on the other Si wafers. In order to suppress the metallic contamination on every type of Si surface below 1010atoms/cm2, the metallic concentration in ultra pure water and high-purity DHF which is employed at the final stage of the cleaning process must be lowered below the part per trillion level. The DHF-$H_2O_2$ solution, however, degrades surface roughness on the substrate with the n+ and p+ surfaces. In order to remove metallic impurities on these surfaces, there is no choice at present but to use the $NH_4OH-H_2O_2-H_2O$ and $HCl-H_2O_2-H_2O$ cleaning.

• Journal of the Korean Vacuum Society
• /
• v.11 no.3
• /
• pp.151-158
• /
• 2002

Fabricated were ultra-shallow $p^+-n$ junctions on n-type Si(100) substrates using decaborane $(B_{10}H_{14})$ ion implantation. Decaborane ions were implanted at the acceleration voltages of 5 kV to 10 kV and at the dosages of $1\times10^{12}\textrm{cm}^2$.The implanted specimens were annealed at $800^{\circ}C$, $900^{\circ}C$ and $1000^{\circ}C$ for 10 s in $N_2$ atmosphere through a rapid thermal process. From the measurement of the implantation-induced damages through $2MeV^4 He^{2+}$ channeling spectra, the implanted specimen at the acceleration voltage of 15 kV showed higher backscattering yield than those of the bare n-type Si wafer and the implanted specimens at 5 kV and 10 kV. From the channeling spectra, the calculated thicknesses of amorphous layers induced by the ioin implantation at the acceleration voltages of 5 kV, 10 kV and 15 kV were 1.9 nm, 2.5 nm and 4.3 nm, respectively. After annealing at $800^{\circ}C$ for 10 s in $N_2$ atmosphere, most implantation-induced damages of the specimens implanted at the acceleration voltage of 10 kV were recovered and they exhibited the same channeling yield as the bare Si wafer. In this case, the calculated thickness of the amorphous layer was 0.98 nm. Hall measurements and sheet resistance measurements showed that the dopant activation increased with implantation energy, ion dosage and annealing temperature. From the current-voltage measurement, it is observed that leakage current density is decreased with the increase of annealing temperature and implantation energy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.390-390
• /
• 2010

Superconducting proximity effects of Nb/Si(111) were investigated with scanning tunneling microscopy(STM) and scanning tunneling spectroscopy(STS). A highly-doped($0.002\;{\omega}{\diamondsuit}cm$) Si wafer pieces were used as substrate and Nb source was thermally evaporated onto the atomically clean silicon substrate. The temperature of the silicon sample was held at $600^{\circ}C$ during the niobium deposition. And the sample was annealed at $600^{\circ}C$ for 30 minutes additionally. Volmer-Weber growth mode is preferred in Nb/Si(111) at the sample temperature of $600^{\circ}C$. With proper temperature and annealing time, we can obtain Nb islands of lateral size larger than Nb coherence length(~38nm). And outside of the islands, bare Si($7{\times}7$) reconstructed surface is exposed due to the Volmer-Weber Growth mode. STS measurement at 5.6K showed that Nb island have BCS-like superconducting gap of about 2mV around the Fermi level and the critical temperature is calculated to be as low as 6.1K, which is lower than that of bulk niobium, 9.5K. This reduced value of superconducting energy gap indicates suppression of superconductivity in nanostructures. Moreover, the superconducting state is extended out of the Nb island, over to bare Si surface, due to the superconducting proximity effect. Spatially-resolved scanning tunneling spectroscopy(SR-STS) data taken over the inside and outside of the niobium island shows gradually reduced superconducting gap.

• Tribology and Lubricants
• /
• v.18 no.1
• /
• pp.1-8
• /
• 2002

Nano adhesion and friction between a $Si_{3}N_{4}$ AFM(atomic force microscope) tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM and LFM(lateral force microscope) modes in various range of normal loads. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and other Si-wafers of different surface roughness were used. Results showed that nano adhesion and friction decreased with the surface roughness. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the load was low.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
• /
• 2007.06a
• /
• pp.19-22
• /
• 2007

반도체 산업은 회로의 고밀도화, 고집적화에 따라 웨이퍼 표면의 입자, 금속, 금속 이온, 유기물 등 오염물의 크기가 미세해 지고 세정에 대한 요구 조건이 더욱 엄격해지고 있다. 현재 세정 공정은 반도체 제조공정 전체에서 약 30%를 차지하고 있으며, 습식 세정 방식이 주로 사용되고 있다.[1] 습식 세정방식은 탈이온수로 린스하고 건조하는 공정이 필연적으로 따르며, 기판 표면에 건조과정에서 물반점이 남는 문제가 가장 큰 이슈로 남아 있다. 본 연구는 웨이퍼의 습식 세정 공정에 사용되는 DHF Final Clean Process후 IPA Vapor를 이용한 건조 방법을 기술 하였다. Single wafer spin process를 이용하였으며, 웨이퍼 Process 공간을 밀폐 후 N2가스를 충진하여 대기중의 산소 오염원 유입을 차단하고 수세 및 건조 가스를 이용하여 건조시킴으로써 SiFx의 SiOx로의 치환을 방지 하여 건조 효율 향상을 목적으로 한다. Bare 웨이퍼에서 65nm 이상 오염 발생 증가량을 측정 하였으며, 공정 후 웨이퍼 오염 발생량을 35개 이하로 확보 하였다.

• Laser Solutions
• /
• v.9 no.3
• /
• pp.7-13
• /
• 2006

Auto focusing system to find optimized focal position of laser beam used for material process has been investigated by using fiber confocal method. Wavelength of laser diode (LD) and diameter of single-mode fiber are 780nm and $5.3{\mu}m$, respectively. Intensity distributions of beam reflected from the surface of mirror and silicon bare wafer have been observed in a gaussian form. Experimental results show that focal position obtained by LD is shifted from one observed from surface scribed by laser about $80{\mu}m$. It is due to the difference of wavelength and each divergence of between LD and laser used for material process. It is confirmed that auto focusing control system through position calibration has operated steadily.