Kim Js

Properties of amorphous tin-doped indium oxide thin films deposited by O2/Ar mixture ion beam-assisted system at room temperature

Abstract Highly transparent and conductive thin films of tin-doped indium oxide (ITO) on glass substrates were grown by the ion beam-assisted deposition (IBAD) technique without any substrate heating. X-Ray diffraction investigations indicated that all films have an amorphous structure and no other crystalline phases. The addition of Ar to O 2 flow and the increased energy of incident ions were found to reduce the resistivity of the grown films. Observed decrease in the resistivity was attributed to the increase in the carrier concentration. In the optimal growth conditions at room temperature, we obtained the electrical resistivity of 4.6×10 −4 Ω-cm, visible transmittance (at λ=550 nm) ≥90%, and optical direct band gap energy of ≅3.75 eV.

Effects of oxygen radical on the properties of indium tin oxide thin films deposited at room temperature by oxygen ion beam assisted evaporation

Abstract In this study, ITO films were deposited by an oxygen ion beam assisted evaporation technique on glass and polycarbonate substrates at room temperature and the effects of oxygen radical on the properties of ITO thin films were investigated. To generate oxygen radicals, in addition to one oxygen ion gun irradiating oxygen ions to the substrate during the ITO deposition, a separate oxygen ion gun was used without applying any voltage to acceleration grid and extraction grid while varying rf power to the ion gun. The increase of rf power to the gun increased the number of oxygen radicals. The increase of oxygen radicals to the oxygen ion beam assisted evaporation of ITO increased the optical transmittance of the ITO deposited on both glass and polycarbonate substrates. The conductivity of the deposited ITO also increased with the increase of oxygen radicals, however, too many oxygen radicals decreased the conductivity of the ITO. Hall measurement showed that the change of the carrier concentration in the film was responsible for the change of the resistivity. The increase of optical transmittance and the change of electrical conductivity with the increase of oxygen radicals were related to the oxygen incorporation to the deposited ITO thin film. ITO deposited on the polycarbonate substrate showed a little lower optical transmittance and conductivity possibly due to the higher surface roughness of the substrate. We were able to obtain room temperature ITO thin film on glass with 5.5×10 −4 Ωcm and above 85% transmittance (at 550 nm) and that on polycarbonate with 6.0×10 −4 Ωcm and approximately 85% transmittance (at 550 nm).

Dry etching characteristics of ITO thin films deposited on plastic substrates

Abstract The dry etching characteristics of indium-tin-oxide (ITO) films deposited on plastic substrates were studied using Ar/CH4 magnetized inductively coupled plasmas (MICP). When conventional inductively coupled plasmas (ICP) were used, the etch rates of ITO films were generally low. However, by using both the multidipole magnets and the axial electromagnets around the chamber wall of ICP, high ITO etch rates >250 nm/min could be obtained at 90% Ar/10% CH4 with the etch selectivity over photoresist higher than that of the ICP. Atomic force microscopy (AFM) measured as a function of Ar/CH4 showed smoother etched ITO surfaces for most of the etch conditions except for high CH4 conditions such as 70% Ar/30% CH4 which generate hydrocarbon polymer on the etched ITO surface. The surface composition characterized using x-ray photoelectron spectroscopy (XPS) showed preferential losses of ITO components depending on the etch gas composition.

Electrical, optical, and structural characteristics of ITO thin films by krypton and oxygen dual ion-beam assisted evaporation at room temperature

Transparent conducting tin-doped indium oxide (ITO) thin films on polycarbonate and glass substrates were deposited without substrate heating and post-deposition annealing using a dual ion-beam assisted evaporation technique, where the bombardment of the growing film surfaces during electron beam evaporation was done using krypton (varied ion flux, J Kr ., and grid acceleration voltage, V a , of the krypton ion source) and oxygen (fixed ion flux and grid acceleration voltage of the oxygen ion source) ion beams. The electrical, optical, and structural effects of krypton ion-beam bombardment of the growing ITO thin films were investigated using Hall-effect measurements, X-ray photoelectron spectroscopy (XPS), UV-visible spectrometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The total film thickness and the deposition rate were 100 nm and 0.06 nm/s, respectively. All ITO films grown with J Kr , = 1.92-3.76 × 10 14 cm -2 s -1 and V a = 100-500 V showed an amorphous structure and no other crystalline phases. As J Kr increased, the electrical conductivity and the optical transmittance of the grown films were improved compared with those of the ITO films deposited using the oxygen ion-beam only. Also, an increase of the bombardment energy by increasing V a of the krypton ion source caused the deterioration of ITO film properties. The conductivity and the optical transmittance of ITO films deposited on polycarbonate substrates were a little lower than those of films on glass substrates. At room-temperature, using optimal growth conditions, the electrical resistivity was as low as 6.4 × 10 -4 Ω cm with an electron carrier concentration n e = 4.3 × 10 20 cm -3 and a Hall mobility μ H = 26.7 cm 2 V -1 s -1 , the visible transmittance (at λ = 550 nm) was 90%, and optical direct band gap energy 3.8 eV.

Ultrahigh Selective Etching of SiO2 Using an Amorphous Carbon Mask in Dual-Frequency Capacitively Coupled C4F8 / CH2F2 / O2/Ar Plasmas

Highly selective etching of a silicon dioxide layer using a very thin physical-vapor-deposited amorphous carbon layer (PVD-ACL) was investigated in a dual-frequency superimposed capacitively coupled plasma etcher. The following process parameters of the C 4 F 8 /CH 2 F 2 /O 2 /Ar plasmas were manipulated: CH 2 F 2 /(CH 2 F 2 + O 2 ) flow ratio, high frequency (HF) power (P HF ), and low frequency power (P LF ). A wide processing window existed to produce the ultrahigh etch selectivities of a SiO 2 layer using the patterned PVD-ACL mask. The etch gas flow ratio played a critical role in determining the process window for ultrahigh silicon oxide/ ACL etch selectivity due to the disproportionate change in the degree of polymerization on the SiO 2 and ACL surfaces. Etching of the ArF photoresist/bottom antireflective coating (BARC)/SiO x ACL/silicon-oxide-stacked structure allows the use of a very thin PVD-ACL as an etch mask layer for the etching of high aspect ratio silicon dioxide patterns.

Indium-tin-oxide thin film deposited by a dual ion beam assisted e-beam evaporation system

Abstract Indium-tin-oxide (ITO) thin films were deposited on polycarbonate (PC) substrates at low temperatures ( 20 cm ×20 cm showed the sheet resistance of less than 40 Ω /sq., the optical transmittance of above 90%, and the uniformity of about 5%.

Tin-doped indium oxide thin film deposited on organic substrate using oxygen ion beam assisted deposition

Abstract Tin-doped indium oxide (ITO) thin films were deposited on polyethylene terephthalate (PET) at room temperature by oxygen ion beam assisted evaporator system and the effects of oxygen gas flow rate on the properties of room temperature ITO thin films were investigated. The increase of oxygen gas flow rate to the ion gun at a fixed rf power consistently decreased not only the oxygen ion densities in the ion gun measured by OES but also the oxygen ion flux to the substrate measured by Faraday cup while the atomic oxygen radical measured by OES showed a maximum at 6 sccm of O 2 with the increase of oxygen flow rate in our experimental conditions. The increase of oxygen flow rate to the ion gun generally increased the optical transmittance of the deposited ITO up to 6 sccm of O 2 and the further increase of oxygen flow rate appears to saturate the optical transmittance. In the case of electrical property, the resistivity showed a minimum at 6 sccm of O 2 with the increase of oxygen flow rate. Therefore, the improved ITO properties at 6 sccm of O 2 appear to be more related to the incorporation of low-energy oxygen radicals to deposited ITO film rather than the irradiation of high-energy oxygen ions to the substrate. At an optimal deposition condition, ITO thin films deposited on PET substrates showed a resistivity of 6.6×10 −4 Ω cm and optical transmittance of above 90%.

Highly selective etching of silicon nitride to physical-vapor-deposited a-C mask in dual-frequency capacitively coupled CH2F2∕H2 plasmas

A multilevel resist (MLR) structure can be fabricated based on a very thin amorphous carbon (a-C) layer (≅80nm) and Si3N4 hard-mask layer (≅300nm). The authors investigated the selective etching of the Si3N4 layer using a physical-vapor-deposited (PVD) a-C mask in a dual-frequency superimposed capacitively coupled plasma etcher by varying the process parameters in the CH2F2∕H2∕Ar plasmas, viz., the etch gas flow ratio, high-frequency source power (PHF), and low-frequency source power (PLF). They found that under certain etch conditions they obtain infinitely high etch selectivities of the Si3N4 layers to the PVD a-C on both the blanket and patterned wafers. The etch gas flow ratio played a critical role in determining the process window for infinitely high Si3N4∕PVD a-C etch selectivity because of the change in the degree of polymerization. The etch results of a patterned ArF photoresisit/bottom antireflective coating/SiOx∕PVD a-C∕Si3N4 MLR structure supported the idea of using a very thin PVD a-C layer a...

Infinitely high etch selectivity during CH2F2/H2 dual-frequency capacitively coupled plasma etching of silicon nitride to chemical vapor-deposited a-C

For fabrication of a multilevel resist (MLR) structure with silicon nitride (Si3N4) and amorphous carbon (a-C) layers, highly selective etching of the Si3N4 layer using a chemical vapor-deposited (CVD) a-C etch mask was investigated by varying the following process parameters in CH2F2/H2/Ar plasmas: etch gas flow ratio, high-frequency source power (PHF), and low-frequency source power (PLF) in a dual-frequency superimposed capacitively coupled plasma etcher. The results of etching the ArF photoresist/bottom antireflective coating/SiOx/CVD a-C/Si3N4 MLR structure showed the possibility of obtaining an infinitely high selective etch process for the Si3N4 layer using a thin CVD a-C etch mask for high aspect-ratio pattern formation. The CH2F2/H2 gas flow ratio was found to play a critical role in determining the process window for infinite Si3N4/CVD a-C etch selectivity, due to the change in the degree of polymerization on Si3N4 and CVD a-C surfaces.

Infinitely high selective inductively coupled plasma etching of an indium tin oxide binary mask structure for extreme ultraviolet lithography

Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics with a completely different configuration than those of conventional photolithography. This study investigated the etching properties of indium tin oxide (ITO) binary mask materials for EUVL, such as ITO (absorber layer), Ru (capping/etch-stop layer), and a Mo–Si multilayer (reflective layer), by varying the Cl2/Ar gas flow ratio, dc self-bias voltage (Vdc), and etch time in inductively coupled plasmas. The ITO absorber layer needs to be etched with no loss in the Ru layer on the Mo–Si multilayer for fabrication of the EUVL ITO binary mask structure proposed here. The ITO layer could be etched with an infinitely high etch selectivity over the Ru etch-stop layer in Cl2/Ar plasma even with a very high overetch time.