Chun-Ming Chang

WO 3 Electrochromic Thin Films Doped With Carbon

(WO₃)_100-XC_X thin films (x=0-9.3 at%) were cosputtered on indium-tin-oxide glass substrate with W and C targets by reactive dc magnetron sputtering at room temperature. The effects of doped C on the microstructure and optical properties of the (WO₃)_100-XC_X thin film were examined by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, and a spectrophotometer. It was found that all of the as-deposited films were amorphous. The average transmittances of bleaching and colored WO₃ film in the 400-700 nm range were 75% and 65.9%, respectively. The variation in average transmittance of the bleaching and colored states of (WO₃)_90.7C_9.3 film was 68.3%. The average transmittance of bleaching (WO₃)_100-XC_X thin films did not vary with C doping. However, the average transmittance of colored (WO₃)_100-XC_X film decreased to <;48% after C doping. In addition, the optical transmittance contrast of (WO₃)_100-XC_X thin films was found to be suitable for blue laser wavelength recording.

Submicron-size patterning on the sapphire substrate prepared by nanosphere lithography and nanoimprint lithography techniques

In this paper, we demonstrate and compare the formation of ordered etching masks for submicron-size patterned sapphire substrates through use of the nanosphere lithography and nanoimprint lithography methods. The metal honeycomb network structure and the polymer pillar protrusion structure were obtained from these two methods. Subsequently, the inductively-coupled-plasma reactive ion etching technique was applied to etch the sapphire substrates, and the etchant mixture gases of boron trichloride and argon with the flow rate ratio of 1 to 6 were introduced into the etchant chamber. Two types of submicron -pattern structures were obtained on the sapphire substrate surface after the etching processes were completed. One type of sapphire substrate was the submicron hole array structure and another type was the submicron cone array structure. The working pressure had a considerable effect on the shape geometry and etching rate, and the possible mechanism is discussed.

A parametric study of ICP-RIE etching on a lithium niobate substrate

Z-cut LiNbO3 single crystal wafers were etched by the inductively coupled plasma reactive ion etching (ICP-RIE) technique by using the boron trichloride (BCl3)/ Argon (Ar) mixture gases. Effects of the ICP power and RF power ranged from 100 W to 700 W of the ICP-RIE system were studied on the etching rate, surface roughness, and corresponding DC bias under different working pressures ranged from 10 mTorr to 50 mTorr, respectively. Besides, photoresist, Cr(20%)/Ni(80%) alloy and Ni thin films were used as the etching mask, and the selective ratios of the three etching masks were also compared. The surface roughness of the etched LiNbO3 substrate was increased when the ICP power and RF power were increased. The etching rate of the LiNbO3 substrate was increased with increasing the ICP power and RF power. It is noted that the etching rate was greater than 100 nm/ min when the working pressure was controlled at 30 mTorr. The selective ratios of the photoresist Cr/Ni and the nickel were calculated to be approximately 0.4, 7, 9, respectively. Under suitable processing parameters of ICP-RIE, the surface roughness less than 40 nm, structure depth greater than 3 μm, and sidewall angle is estimated to be 120° of the LiNbO3 substrate can be obtained within 28 min, which etching rate is greater than 117 nm/ min.

Zinc Oxide Column Rod Array Prepared by Inductively Coupled Plasma-Reactive Ion Etching Technology

The nano-scale zinc oxide column rod array is produced by ICP-RIE and nano-sphere lithography. The rod diameter of 54nm is realized.

Patterning of multilayer dielectric optical filters using metal masks fabricated by electroforming and photolithography

Ni films, replacing photoresists, serve as masks in the selective deposition of optical thin films by electron-beam gun evaporation at a substrate temperature of 300°C. Photolithography is adopted herein to define the growth of Ni films by electroforming. Mosaic patterns with a width of 20 µm are employed as red color filters, which are longwave pass. These red filters are formed from alternate SiO 2 and TiO 2 layers and have a mean transmittance of >90%. The experimental results show that the combined use of photolithography, electroforming, and electron-beam gun evaporation can deposit miniaturized multilayer dielectric coatings with high light transmittance in a hot process.

Mechanical behavior of photopolymer for additive manufacturing applications

The use of additive manufacturing (AM) is expanding rapidly; however, the mechanical behavior of printing materials has yet to be fully elucidated. In this study, we examined UV-cured photopolymers designed for use in PolyJet systems. We tested the shore hardness and impact characteristics of the photopolymer in accordance with ASTM D2240-15 and ASTM D256-10, respectively. The coefficient of variance among shore hardness measurements was low. We also investigated the influence of stress concentrators fabricated using additive (3D printing) or subtractive (milling) manufacturing methods. Overall, specimens with an AM stress concentrator were approximately 15% stronger than those with a milled stress concentrator. Our results provide a valuable reference pertaining to the mechanical behavior of photopolymers.

Development of catalytic etching using dual materials

In this study we presents an effective and simple process for forming multi-level vertical structures on a (100) silicon wafer. The dual materials including gold and platinum was employed as catalytic material in the etching process. We employed an etchant solution consisting of 4.6 M hydrofluoric acid, 0.44 M hydrogen peroxide, and isopropyl alcohol to produce microstructures at an etching rate of 0.294 μm/min and 0.648 μm/min during only gold (Au) and platinum (Pt) film, respectively. For the catalytic etching process with 10 nm-thick Au and Pt, the etching rate yield from Au film was increased to that generated from the etching process with single Pt film. In the meantime, the etching structure under Pt film became not obvious in the dual materials etching process. For the sample with 10 nm Au and 11 nm Pt, the significant etching produced on both Au and Pt region.

Development of composite vertical wet etching for silicon material

In this research, we combined the electrochemical etching (ECE) and the metal-assisted chemical etching (MACE) to develop a composite vertical etching process for silicon material and then discuss the etching results influenced by experimental parameters. The experimental results show that the developed composite etching process has faster etching rate than both electrochemical etching and metal-assisted chemical etching process. When a bias of 0.25V is applied and the catalytic material is 10nm in thickness, a 30μm-depth vertical structure can be generated which is 3 times than the structure yield by metal-assisted chemical etching.

Dual photoresist complimentary lithography technique produces sub-micro patterns on sapphire substrates

Dual photoresist complimentary lithography technique consisting of inorganic oxide photoresist and organic photoresist is applied to produce the sub-micro pit patterns on a sapphire surface. The oxide photoresist is patterned by the direct laser writing and the developed mark size decreases to a smaller value than the laser spot size due to the thermal lithography. The small developed pit diameter is one of the advantages using oxide photoresist. The oxide photoresist possesses strong etching resistance against the oxygen plasma but shows no resistance against the chlorine plasma. The chlorine plasma is a necessary component to etch the sapphire during the ion-coupled-plasma reactive-ion-etching process because of sapphire’s mechanical hardness and chemical stability. However, the characteristics of organic resist SU8 are opposite to that of oxide photoresist and possess moderate resistance against chlorine plasma but show no resistance to oxygen plasma. The thermal and developing characteristics of oxide photoresist are reported here. The dependence of the laser power on the developed mark sizes and morphologies is illustrated by atomic force microscopy. The temperature distribution on the photoresist structure during the laser writing is simulated. Images of patterned pits on the large commercial sapphire substrates are also shown.

Dual-photoresist complementary lithography technique for the formation of submicron patterns on sapphire substrates

Abstract. Dual-photoresist complementary lithography technique consisting of inorganic oxide photoresist and organic photoresist is applied to produce the submicron pit array patterns on a sapphire surface. The oxide photoresist is patterned by direct laser writing, and the developed pit size decreases to a smaller value than the laser spot size due to the thermal lithography. The oxide photoresist possesses strong etching resistance against oxygen plasma but shows no resistance against chlorine plasma. During the ion-coupled-plasma reactive-ion-etching process, chlorine plasma is a necessary component to etch the sapphire. Moreover, the characteristics of organic resist are opposite those of oxide photoresist and possess moderate resistance against chlorine plasma but no resistance against oxygen plasma. The thermal and developing characteristics of oxide photoresist are reported in this study. The dependence of laser power on the developed mark sizes and morphologies is examined by atomic force microscopy. The temperature distribution on the photoresist structure during the laser writing is simulated, and the thermal lithography concept is introduced to explain the effect of power on the developed oxide mark width. Images of patterned pit array on a commercial 4-inch-diameter sapphire substrate are also shown.