DNQ-Novolak based photoresists are applied in many fields of microstructure technology. A common feature of such resist structures (>lOjim) described in the literature is a concave profile with the narrowest part at approximately 2/3 of the resist height. By newly including effects of residual solvent concentration, the simulation program accurately describes characteristic resist profiles for AZ4562 between 10 and iøøm resist thickness. The program calculates the vertical distribution of the residual solvent concentration by modeling the evaporation during prebake as a three step process: diffusion of solvent within the resist film to the surface, a transfer to the ambient air described by a phase equilibrium and a transport away from the surface described by convection. Required parameters of the model have been obtained by fitting measured evaporation rates as function of time with the prebake temperature as a parameter to calculated ones. Resist exposure is simulated in vertical and one lateral dimension using the well known Dill's theory with ABC-parameters for DNQ resists. The development process is described by percolation theory where the residual solvent concentration increases the percolation parameter and therefore the local development rate. This paper describes details of the mathematical models used, demonstrates good agreement between experimentally observed profiles and simulated ones and shows that the influence of process parameters such as prebake temperature or time on resist profiles can be accurately simulated.
In this paper, a prototype of 2 mm-diameter micro-cycloid gear system fabricated by the multi-exposure LIGA technique is presented. The gear system is composed of a casing and three vertically stacked disks and gears. Each part consists of three different levels. The ®rst level, 40 lm high, was fabricated by UV-lithography, and the second as well as the third level, 195 lm and 250 lm high respectively, were processed by aligned deep X-ray lithography (DXL). The alignment error between two DXL-processed layers has been measured to be within 5 lm range. As a result of the height control process, the deviation of structural height has been maintained within 3 lm range for the UV-lithography-processed structures, and 10 lm for the DXL-processed structures. Preliminary tests of gear assembly have been implemented with 125 lm-diameter commercially available glass ®ber, and the further efforts are being carried out. IntroductionA simple shadow casting in deep X-ray lithography (DXL) creates patterns with quality vertical walls and high aspect ratios. However the requirements for the current microparts application include more complex 3D geometry and multi-level con®gurations [1]. The 3D structural formation with LIGA technique can be primarily classi®ed into two categories, i.e. the one based on the sequential planar formation of individual levels to form 3D structures [2], and the other with spatial alternation of the absorbed dose typically implemented by the mask-dragging [3]. Regarding the sequential approach, the additional processes such as the replanarization after the electroplating as well as the mask-alignment procedure are involved between each conventional DXL cycle. These complementary processes give another constraint in the maximum attainable fabrication precision, and it is considered to approximately be in the range of 5 lm with regard to the typical resist thickness of the several tens to hundreds microns [4]. Whether this precision range can meet the requirement of today's practical movable micro-parts is of great interest.In this paper, a prototype of an encapsulated microcycloid gear system is presented. Following the explication about the design and the fabrication detail, the results of the measurement about the alignment accuracy between two DXL-processed layers are presented. The results on the height controllability of the UV-lithography-processed as well as the DXL-processed components are also reported. The controllability of the structural height by mechanical polishing is discussed as well. 2Design and functionality Figure 1 shows a schematic of the cross-sectional view of the micro-cycloid gear system. The overall dimension is 2 mm in diameter and 1.15 mm in height. The system comprises four parts, namely driving disk, internal 17-tooth gear, output-torque disk and casing. The eight 40 lm-high turbine blades provided underneath the driving disk activate the system by means of the working gas introduced from the inlet hole on the bottom lid. The axis of the 400 lm-diameter boss sits 32 lm o...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.