Papers by Keyword: Lithography

Abstract: We designed a lithographic system, which consists of an ultraviolet LED array as the source, a Compound Parabolic Collector (CPC) as the light collection and collimator, a double fly’s eye len and a convergent lens as light energy Homogenization unit. The second fly’s lens as a field lens is placed to the back focal plane of the first one to improve the light energy uniformity as the light rays output from the CPC are not strictly parallel. The simulation based on optical software indicated that the lithographic system is good at collecting and distributing uniformly light energy. It is a better solution as ultraviolet LED is good at space, price, Environmental Protection compared with Ultraviolet (UV) laser and high pressure mercury lamp.

Abstract: Complex microstructures can be fabricated on nickel template directly by femtosecond laser. But the efficiency is low and much time is inevitable when large scale microstructures are fabricated. The multi-beam interference provides an effective method for fabrication of large scale microstructures. This paper mainly focuses on direct ablation of nickel template by four-beam interference and fabricating periodic microstructures by laser interference lithography. Experimental results show that submicron periodic stripes and column structures can be produced on the nickel template by laser interference, laying the foundation of making nickel molds for microfluidic chips.

Abstract: A novel micro spring with steel structures is described here. It can be fit into a specially designed microtensile apparatus, which is capable of carrying out a series of tests on micron scale freestanding thin films. This method is suitable for thin metal films or polymer layers with large strain and can be applied to samples with different thicknesses. The novel fabrication method uses the conventional lithography and electrochemical metal etching techniques. A single photomask is used to define the whole structure, resulting in a simple and inexpensive fabrication process. The method proposed here is promising for the low cost fabrication of micro spring based on steel. A micro spring of 100μm wide, 100μm thick, with 200μm diametric of the semicircle and 6 turns was prepared by this method; the elasticity of the spring is 147.3N / m. A gold wire was measured by this micro spring. The young's modulus and ultimate tensile strength of the gold wire were 30Gpa and 120Mpa, respectively.

Abstract: This work presents a cost-effective and simple possibility to outperform the potential of a standard single side mask aligner. The limited functionality is extended to the capability of back side alignment with minimal effort without additional knowledge and integration of new process technologies. The whole presented process flow performs without the necessity of additional equipment as infrared back side wafer alignment kits or additional etching processes or clamps and brackets. The result is a front to back side alignment process with satisfactory deviation.

Abstract: Double fold reduction projection lithography objective lens with bi-telecentric configuration, consists of 6 lenses and the number aperture , is designed based on the optical design software Zemax. It uses the 405nm laser diode (LD) as light source. The spatial resolving capacity approaches to 5um. In a field of view of , its wave-front aberration is less than a quarter of wave-length and the distortion ratio is not more than. The imaging performance, in particular, the accurate modulation transfer function (MTF) value of the projection objective lens being fabricated by experiments is determined in this paper. Through analyzing the noise disturbance law in MTF tests, the result show that the projection objective lens has sub ten micrometer resolving ability.

Abstract: In the process of integrated circuit design and manufacturing, dummy metal fill can improve the planarity of layout after Chemical Mechanical Polishing (CMP). However, it will also cause lithography distortion and Critical Area (CA) variation. This paper compares and analyzes the influences of lithography distortion due to metal fill on CA from the perspectives of different defect particles based on 45nm technology node. The results indicate that dummy metal fill can increase open CA after lithography and the defect particle with the diameter of 0.066um leads to the largest increment percentage of open CA, which will take up almost 10%. This paper is instructive in researching dummy metal fill and CA or related fields in the future.

Abstract: With the increasing needs for high-performance gas sensors in industrial production, environmental monitoring and so on, the research on gas sensors is becoming more and more important. In this paper, the electric field intensity distribution simulation process of the interdigital microelectrodes (IMEs) is discussed in details to get the proper electrode structural parameters. The IMEs on the ITO surface with a minimum gap of about 4μm are achieved by lithography, which provides a reliable, low-cost manufacturing method. Sensitive components are made of the multi-walled carbon nanotubes modified materials. The gas-sensing property of the sensor is detected for ammonia. The experiment result shows that the performance of the nanomodified sensor is obviously improved.

Abstract: Scanning probe lithography such as atom force microscopy (AFM) has the highest spatial resolution. SPM etching technique employed conductive SPM probe as cathode and metal or semiconductor surface as anode. This paper reports the construction of nanopatterns by conductive nanoetching method on HDT modified Au (111) surface. With Pt-plated probe tip, nanowires of a minimum width of 176 nm was fabricated. The study shows that AFM lithography could be an alternative technology to e-beam lithography and focused-ion-beam.

Abstract: Small field ArF projection optics for experiment is favorable to the prospective study and key technique development for lithography equipment. An ArF projection optics has been designed with specifications of 0.75 numerical aperture (NA), 100μm image field of view and 40X reduction ratio. The designed composite root-mean-square (RMS) of wave front error of the system can reach 0.03λ (λ=193.29nm). To achieve diffraction limited resolution, the optical manufacture tolerances of this high-NA projection optics are too tight to manufacture, such as radius error within ±0.01%, central thickness within ±2μm and surface figure error less than peak-valley (P-V) of 1/30λ (λ=632.8nm). In this paper, two effective compensatory methods are presented to relax the manufacture tolerances before assembly. One method is re-computation of air spaces including actual measured values of the radii of curvature and center thickness for each element. The second method is rotating lenses to find the best matching manner of measured surface figure. The results show that radius error, central thickness error and surface figure error can be compensated significantly，and the best performance of the projection optics disregarding assembly error has been acquired. The composite wave front error RMS can reach 0.09λ (λ=193.29 nm) after compensation, which is much smaller than 0.25λ before compensation under the same optical manufacture error. Both methods can also be used in development of industrial lithographic projection optics.

Abstract: Largely owing to the high cost of masks for lithography, recently there is a strong interest in maskless lithography. Maskless lithography is a potential program to overcome the high cost caused by rising price of the masks. Because of the advantages of low cost, high flexibility and short production cycle, digital mirror device (DMD)-based maskless lithography has been brought storm attention by people. Both the theory and experiment of DMD-based maskless lithography achieved good results. Maskless lithography systems based on DMD are analyzed in this review. Principles of construction, examples of implication, as well as future development direction are discussed.