Chen Jimin

Fabrication of microtransmittance grating using laser induced backside dry etching

Laser induced backside dry etching (LIBDE) is a novel technique, which applied in the micromachining and nanomachining of transparent dielectric materials used for optical elements by direct laser irradiation with the assistance of solid mediums as an absorbed layer. On the basis of exploring two different solid mediums, i.e. Al2O3 powder and alumina ceramic wafer as absorbers, LIBDE with 1064 nm central wavelength pulsed ytterbium doped fiber laser as the irradiation source was successfully applied for the fabrication of periodical microscaled structures on fused silica. The threshold of laser fluence to etch fused silica was 7.47 J/cm2 extrapolated from the experimental data. By using alumina ceramic wafer as the absorber, a microbinary dimensional transmittance grating with the constant of 25 μm was obtained on the silica. The depth of the trench is 4.2 μm, and the root mean square roughness of the trench bottom is below 40 nm according to the measurement of 3D profiler. Additionally, diffraction patte...

Laser microfabrication with metallic powder

Rapid prototyping (RP) technology has developed fast in the last year. It is an inevitable trend to adopt laser melting metal powder material directly to make metal parts from RP technology to rapid manufacturing. However, at present it is still at the stage of explorlation to utilize micro powder metal material for microfabrication. In this article two methods of microfabrication were investigated. One is selective laser microsintering. Equipment of YAG doubling frequency laser was used to sinter metallis powder materials to fabricate the micro part. Another is microladding fabrication. With special designation of a powder feeder the fused deposition of metallic powder was conducted. The impact factors such as laser parameters, processing parameters on microfabrication, were analyzed. Through optimization in the parameters, a micrometal part has been successfully fabricated.

Laser induced backside wet and dry etching of solar glass by short pulse ytterbium fiber laser irradiation

Microstructures fabricated on the surface of solar glass have the potential to improve the performance of solar cells. In this paper, in order to overcome the high transmittance to 1064 nm center wavelength fiber laser irradiation and realize high efficiency process on transparent glass substrates, different absorber materials, including alumina powder, alumina ceramic wafers, and copper sulphate solutions, were applied for dry and wet etching under the irradiation of 1064 nm pulsed fiber laser respectively. The laser fluence was varied from 7 to 10 J/cm2 with a pulse repetition rate of 20 kHz. The morphology of trenches etched by means of laser induced backside dry etching (LIBDE) and by laser induced backside wet etching was measured using a scanning electronic scope, and compared from the aspects of etch depth and width, as well as the roughness. On the basis of this comparison, a higher etch rate can easily be obtained by dry etching, while lower roughness is a feature of wet etching. The mechanism of...

Laser micro-fabrication in RF MEMS switches

The RF MEMS Switch is the key element in the field of microwave and mm-wave signal control. In recent years it has been investigated widely because of its advantages of low insertion loss, low power consumption, high isolation, excellent compatibility with silicon and high linearity over PIN diode or FET counterpart. Meanwhile as the development of laser technology it has demonstrated extensively to be a very valuable tool for the development of high quality processes in micro-applications. The use of lasers in the field of MEMS is multiple. Starting from characterization, testing and going to technology and working principle of the microsystems and nanosystems, the lasers find applications in any of these areas. The paper overviews some of the laser micro fabrication in RF MEMS switches such as laser deposition, laser lithography, laser direct writing etc. We present the respective technologies, their working principles, their advantages and drawbacks. In some cases the examples of microstructures realized by using laser techniques have been showed.

Laser micro fabrication: Material removing or adding

Currently there are many laser micro fabrication technologies. The technologies are based on the philosophy of either subtractive material from top to down or additive material by bottom up. Laser ablation for instant removes material gradually to produce microstructure. Most common used lasers are ultrafast or UV laser. CO2 or YAG laser also can be found to apply in micro fabrication. Another approach such as micro stereo lithography(uSLA) and selective laser sintering(SLS) adds the materials from bottom to top layer by layer. In this paper the authors introduced a novel technology Laser Vaporizing Sintering(LVS) which combines material removing and adding together: This technology removes the powder material with laser vaporizing and meanwhile sinters the powder material to form micro structure by laser. Several powder particles can be sintered to form a thin wall. It shows great potential advantages to fabricate micro parts.Currently there are many laser micro fabrication technologies. The technologies are based on the philosophy of either subtractive material from top to down or additive material by bottom up. Laser ablation for instant removes material gradually to produce microstructure. Most common used lasers are ultrafast or UV laser. CO2 or YAG laser also can be found to apply in micro fabrication. Another approach such as micro stereo lithography(uSLA) and selective laser sintering(SLS) adds the materials from bottom to top layer by layer. In this paper the authors introduced a novel technology Laser Vaporizing Sintering(LVS) which combines material removing and adding together: This technology removes the powder material with laser vaporizing and meanwhile sinters the powder material to form micro structure by laser. Several powder particles can be sintered to form a thin wall. It shows great potential advantages to fabricate micro parts.

The development of laser microprocessing in China

In 1995 the National Center of Laser Technology (NCLT) of China was opened. From that time there has been research on laser microfabrication at NCLT. Under the support of the National Science Foundation and Beijing Science Foundation several projects involving laser micro processing have been carried out. NCLT has make great progress in the field of laser micro processing with excimer laser and powder microsintering using YAG laser. Based on the principle of excimer laser micromachining, a micromachining system, including a beam delivery system, mask illumination system based on fly’s eye homogenizer, double telecentric optical and electrical system, has been developed. The application of micromachining technology to the fabrication of MEMS has been conducted and 50∼500µm diameter micro-gears have been made using polymers and ceramics. Meanwhile the excimer laser has been to manufacture microfluid biochip. Besides this the microfabrication using laser sintering powder material has been investigated at NCLT. This represents the one aspect of the development of laser microprocessing in China.In 1995 the National Center of Laser Technology (NCLT) of China was opened. From that time there has been research on laser microfabrication at NCLT. Under the support of the National Science Foundation and Beijing Science Foundation several projects involving laser micro processing have been carried out. NCLT has make great progress in the field of laser micro processing with excimer laser and powder microsintering using YAG laser. Based on the principle of excimer laser micromachining, a micromachining system, including a beam delivery system, mask illumination system based on fly’s eye homogenizer, double telecentric optical and electrical system, has been developed. The application of micromachining technology to the fabrication of MEMS has been conducted and 50∼500µm diameter micro-gears have been made using polymers and ceramics. Meanwhile the excimer laser has been to manufacture microfluid biochip. Besides this the microfabrication using laser sintering powder material has been investigated at NCL...

The investigation on laser microfabrication with metallic powder

Rapid Prototyping (RP) technology develops fast recent year. It is an inevitable trend to adopt laser melting metal powder material directly to make metal part from RP technology to RM (Rapid Manufacturing). However at present it is still at the stage of exploring to utilize micro powder metal material for micro-fabrication. In this paper two methods of microfabrication were investigated. One is selective laser micro sintering. Equipment of YAG doubling frequency laser was used to sinter metallic powder materials to fabricate micro part. Another is microcladding fabrication. With special designation of powder feeder the fused deposition of metallic powder was conducted. The impact factors such as laser parameters, processing parameters on micro fabrication were analyzed. Through optimization in the parameters, a micro metal part has been successfully fabricated.Rapid Prototyping (RP) technology develops fast recent year. It is an inevitable trend to adopt laser melting metal powder material directly to make metal part from RP technology to RM (Rapid Manufacturing). However at present it is still at the stage of exploring to utilize micro powder metal material for micro-fabrication. In this paper two methods of microfabrication were investigated. One is selective laser micro sintering. Equipment of YAG doubling frequency laser was used to sinter metallic powder materials to fabricate micro part. Another is microcladding fabrication. With special designation of powder feeder the fused deposition of metallic powder was conducted. The impact factors such as laser parameters, processing parameters on micro fabrication were analyzed. Through optimization in the parameters, a micro metal part has been successfully fabricated.