Abstract
A stepped copper microcolumn array was fabricated based on the UV-LIGA technology and microelectroforming process using THB-151N photoresist. In order to solve the problems of difficult development of 20 μm blind microvia and “resist retention” at the bottom during THB-151N photoresist development, a submerged bidirectional megasonic assisted development method was proposed. Comsol Multiphysics software was used to analyze the mass transfer process of developer in blind microvia under different megasonic power densities and aspect ratios, and the mass transfer coefficient was used to characterize the process. According to the actual working conditions, the optimized megasonic power density of 3.2 W/cm2 and aspect ratio of 1.5 are selected and the megasonic assisted development was studied experimentally. Besides, aiming at the poor verticality of side wall of the blind microvia due to inappropriate exposure dose of THB-151N photoresist film, the effect of exposure dose on the verticality of side wall of the blind microvia was discussed by lithography experiment and the Angle β is introduced to measure the verticality of the side wall. The empirical equation between exposure dose and thickness of the film was fitted.On the basis of the above technological methods and experimental study, stepped Cu microcolumn arrays of 4 × 6 with a height of 300 μm, overall aspect ratio of 15:1 and minimum side length of 20 μm were fabricated.
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The data that support the findings of this study are available from the corresponfing author, [Liqun Du], upon reasonable request.
References
Andok R, Vutova K, Koleva E, et al. (2021) Dependence of PMMA electron beam resist sidewall shape on exposure dose and resist thickness. In: 26th International Conference on Applied Physics of Condensed Matter (APCOM), Štrbske Pleso, Slovak Republic: 040001. https://doi.org/10.1063/5.0067068
Anthony R, Kulkarni S, Wang N, Mathuna CO (2014a) Advanced processing for high efficiency inductors for 2.5D/3D power supply in package. 2014a Int 3D Syst Integr Conf (3DIC), Kinsdale, Ireland, pp 1–4. https://doi.org/10.1109/3DIC.2014.7152183
Anthony R, Wang N, Kulkarni S et al (2014b) Advances in planar coil processing for improved microinductor performance. IEEE Trans Magnetics Dresden Germany 50(11):1–4. https://doi.org/10.1109/TMAG.2014.2330361
Anthony R, Laforge E, Casey DP, Rohan JF, O’Mathuan C (2016) High-aspect-ratio photoresist processing for fabrication of high resolution and thick micro-windings. J Micromech Microeng 26:105012. https://doi.org/10.1088/0960-1317/26/10/105012
Baldhoff T, Nock V, Marshall AT (2018) Review—through-mask electrochemical micromachining. J Electrochem Soc 165:E841–E855. https://doi.org/10.1149/2.1341814jes
Bhushan A, Yemane D, Overton EB, Goettert J, Murthy MC (2007) Fabrication and preliminary results for LIGA fabricated nickel micro gas chromatograph columns. J Microelectromech Syst 16:383–393. https://doi.org/10.1109/JMEMS.2007.892903
Chamran F, Yeh Y, Min HS, Dunn B, Kim CJ (2007) Fabrication of high-aspect-ratio electrode arrays for three-dimensional microbatteries. J Microelectromech Syst 16:844–852. https://doi.org/10.1109/JMEMS.2007.901638
Daunton R, Gallant AJ, Wood D (2012) Manipulation of exposure dose parameters to improve production of high aspect ratio structures using SU-8. J Micromech Microeng 22(7):075016. https://doi.org/10.1088/0960-1317/22/7/075016/meta
Dixit P, Tan CW, Xu L, Lin N, Miao J, Pang JHL, Backus P, Preisser R (2007) Fabrication and characterization of fine pitch on-chip copper interconnects for advanced wafer level packaging by a high aspect ratio through AZ9260 resist electroplating. J Micromech Microeng 17:1078. https://doi.org/10.1088/0960-1317/17/5/030
Dixit P, Salonen J, Pohjonen H, Monnoyer P (2011) The application of dry photoresists in fabricating cost-effective tapered through-silicon vias and redistribution lines in a single step. J Micromech Microeng 21:025020. https://doi.org/10.1088/0960-1317/21/2/025020/meta
Holt R, Oberlander JE, Calindas MFY et al. (1998) Method to measure ethylene oxide/propylene oxide surfactants in resist developers. In: 15th Annual SPIE Conference on Advances in Resist Technology and Processing, Santa Clara, CA, pp 1103–1114. https://doi.org/10.1117/12.312456
Hsu CY, Chen LT, Chang JS, Chu CH (2007) A thick photoresist process for open-channel sensing packaging applications by JSR THB-151N negative UV photoresist. 2007 Int Microsyst, Packag, Assem and Circuits Technol. conf. pp 288–291. https://doi.org/10.1109/IMPACT.2007.4433619
Hu YY, Zhu D, Qu NS, Zeng YB, Ming PM (2009) Fabrication of high-aspect-ratio electrode array by combining UV-LIGA with micro electro-discharge machining. Microsyst Technol 15:519–525. https://doi.org/10.1007/s00542-008-0745-6
Lee H, Lee K, Ahn B, Xu J, Xu LF, Who K (2011) A new fabrication process for uniform SU-8 thick photoresist structures by simultaneously removing edge bead and air bubbles. J Micromech Microeng 21:1250006. https://doi.org/10.1088/0960-1317/21/12/125006
Li J, Chen D, Zhang J, Liu J, Zhu J (2006) Indirect removal of SU-8 photoresist using pdms technique. Sens Actuators A 125(2):586–589. https://doi.org/10.1016/j.sna.2005.07.012
Liu G, Huang X, Xiong Y, Tian Y (2008) Fabricating HARMS by using megasonic assisted electroforming. Microsyst Technol 14:1223–1226. https://doi.org/10.1007/s00542-007-0556-1
Luo SY, Yu TH, Hu YC (2007) Fabrication of micro nickel/diamond abrasive pellet array lapping tools using a LIGA-like technology. J Micromech Microeng 17:1130–1138. https://doi.org/10.1088/0960-1317/17/6/005
Marques C, Kelly KW (2004) Fabrication and performance of a pin fin micro heat exchanger. J Heat Transfer 126:434–444. https://doi.org/10.1115/1.1731341
Nam Y, Sharratt S, Byon C, Kim SJ, Ju YS (2010) Fabrication and characterization of the capillary performance of superhydrophilic cu micropost arrays. J Microelectromech Syst 19:581–588. https://doi.org/10.1109/JMEMS.2010.2043922
Nilson RH, Griffiths SK (2002) Enhanced transport by acoustic streaming in deep trench-like cavities. J Electrochem Soc 149:G286–G296. https://doi.org/10.1149/1.1459716
Peng ZL, Wang ZL, Wang YK, Dong YH, Chen H (2009) Study on micro reversible electrical discharge machining method for the fabrication of micro structures. Mater Sci Forum 626–627:279–284. https://doi.org/10.4028/www.scientific.net/MSF.626-627.279
Powers SE, Abriola LM, Weber WJ (1992) An experimental investigation of nonaqueous phase liquid dissolution in saturated subsurface systems: steady state mass transfer rates. Water Resour Res 28:2691–2705. https://doi.org/10.1029/92WR00984
Rao VS, Kripesh V, Yoon SW, Tay AAO (2006) A thick photoresist process for advanced wafer level packaging applications using JSR THB-151N negative tone UV photoresist. J Micromech Microeng 16:1841–1846. https://doi.org/10.1088/0960-1317/16/9/012
Schuster R, Kirchner V, Allongue P, Ertl G (2000) Electrochemical micromachining. Science 289:98–101. https://doi.org/10.1126/science.289.5476.98
Shan Z, Wang G, Zhu Y et al. (2010) Process optimization for a high gate trench MOS to minimize threshold voltage variation. In: 2010 International Conference on Green Circuits and Systems (ICGCS), Shanghai, China, pp 491–494. https://doi.org/10.1109/ICGCS.2010.5543014
Xiao R, Enright R, Wang EN (2010) Prediction and optimization of liquid propagation in micropillar arrays. Langmuir 26:15070. https://doi.org/10.1021/la102645u
Yu W, Desmulliez MPY, Drufke A, Leonard M, Dhariwal RS, Flynn D, Bognar G, Poppe A, Horvath G, Kohari Z, Rencz M (2010) High-aspect-ratio metal microchannel plates for microelectronic cooling applications. J Micromech Microeng 20:025004. https://doi.org/10.1088/0960-1317/20/2/025004
Zhai K, Du L, Wen Y, Wang S, Cao Q, Zhang X, Liu J (2020) Fabrication of micro pits based on megasonic assisted through—mask electrochemical micromachining. Ultrasonics 100:105990. https://doi.org/10.1016/j.ultras.2019.105990
Zhang H, Zhang N, Fang F (2021) Investigation of mass transfer inside micro structures and its effect on replication accuracy in precision micro electroforming. Int J Mach Tools Manuf 165:103717. https://doi.org/10.1016/j.ijmachtools.2021.103717
Zhao M, Du L, Qi L, Li YQ, Li Y, Li X (2018) Numerical simulations and electrochemical experiments of the mass transfer of microvias electroforming under ultrasonic agitation. Ultrason Sonochem 48:424–431. https://doi.org/10.1016/j.ultsonch.2018.07.002
Zhao M, Du L, Du C, Wei Z, Ji X, Bai Z, Liu X (2019) Quantitative study of mass transfer in megasonic micro electroforming based on mass transfer coefficient: simulation and experimental validation. Electrochim Acta 297:328–333. https://doi.org/10.1016/j.electacta.2018.12.018
Acknowledgements
This work was supported by the National Key R&D Program of China (2022YFB4601602) and the National Natural Science Foundation of China (51975103).
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Du, L., Yuan, B., Guo, B. et al. Fabrication of high-aspect-ratio stepped Cu microcolumn array using UV-LIGA technology. Microsyst Technol 29, 999–1014 (2023). https://doi.org/10.1007/s00542-023-05491-0
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DOI: https://doi.org/10.1007/s00542-023-05491-0