- Email: [email protected]
A piezodriven XY-microstage for multiprobe nanorecording
Sensors and Actuators A 108 (2003) 230–233
A piezodriven XY-microstage for multiprobe nanorecording Deyuan Zhang a,∗ , Chienliu Chang b , Takahito Ono b , Masayoshi Esashi c a
Department of Mechanical Engineering and Automation, Beihang University, Beijing 100083, China Faculty of Engineering, Tohoku University, 01 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan New Industry Creation Hatchery Center, Tohoku University, 01 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan b
c
Received 29 July 2002; received in revised form 9 May 2003; accepted 5 June 2003
Abstract The properties of electrostatic, electromagnetic and piezoelectric actuators used for XY-microstage are compared to indicate high area efficiency but no good machinability of piezoelectric actuator, so that a novel planer fabrication method of the piezodriven XY-microstage with one PZT plate has been proposed. This fabrication method includes three processes, dicing, electroplating, femtosecond laser machining and so no. A parallelogram mechanism with flexure hinges, lever mechanisms and piezoelectrical actuators has been designed to make XY-displacement in monolayer plane structure. The area efficiency and volume efficiency of piezodriven XY-microstage are very higher than electrostaticdriven and electromagneticdriven one. The relationship of displacement characteristics with the sizes of parallelogram mechanism has been tested with the several principium prototypes fabricated by femtosecond laser machining of single nickel plate and assembly of PZT actuator. The test results show that the flexure hinges the shorter, the accuracy of the XY-displacement the better. Thirty micrometer displacement and 50% and above area efficiency have been obtained in the principium prototype. © 2003 Elsevier B.V. All rights reserved. Keywords: XY-stage; PZT; Multiprobe nanorecording
1. Introduction Magnetic and optical storage are approaching its physical limits due to the super-paramagnetic effect and the limitation of light diffraction, respectively. In Venture Business Laboratory of Tohoku University, a multi-heater-probe nanorecording system for application of ultra high density data storage beyond 1 Tbit/in.2 (25 nm bit) recording density was developed by means of a novel batch-fabrication method, and the near-field optical probe and focused electron beam probe for noncontact data storage were investigated, and the probes with a sub-100 nm heater were arrayed onto a glass substrate on 100 m centers [1]. The recording range of one probe in a disk is a 100 m × 100 m area. The bits are recorded onto the area on a several nanometer centers. Therefore a XY-microstage with 100 m × 100 m displacement range and nanometer resolution must be developed for driving of the high-density data storage disk. Up to now, the developed XY-microstages in the world were driven most by electrostatic actuator or electromagnetic actuator [2–5]. There is few or no piezodriven ∗ Corresponding author. Tel.: +86-10-8231-5654; fax: +86-10-8231-6603. E-mail address: [email protected] (D. Zhang).
0924-4247/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0924-4247(03)00373-X
XY-microstage because piezoelectric material is very difficult to micromachine by means of processing method of semiconductors. The PZT actuators are usually applied to larger XY-stage by means of assembling process. The properties of electrostatic, electromagnetic and piezoelectric actuators used for XY-microstage are compared as shown in Table 1. In the case of electrostatic type stage, the processing method of semiconductors can be used, so that this type of actuator is applied most widely for MEMS field, but the area efficiency of electrostatic XY-stage for the data storage is very poor because of low driven force, small displacement, careful insulation and a lot of comb probes. Usually the area efficiency of electrostatic XY-stage is less than 5%. Therefore it is at great disadvantage for miniaturization of whole multiprobe nanorecording system. In the case of electromagnetic type stage, the area efficiency and displacement range for the data storage are larger than ones of electrostatic type stage, but the volume and weight of whole stage are very large, and the assembling process of several permanent magnet is required in fabrication process. So that it is also at disadvantage for miniaturization of whole multiprobe nanorecording system. In the case of piezoelectric type stage, the volume power and the displacement accuracy of piezoactuator are very
D. Zhang et al. / Sensors and Actuators A 108 (2003) 230–233
231
Table 1 Comparison of typical actuators Properties
Actuators Electrostatic
Electromagnetic
Piezoelectric
Volume power Area efficiency Volume efficiency Machinability Displacement Frequency response Displacement accuracy
× ×
× ×
䊊 䊊 䊊
䊊
×
䊊
× ×
䊊 䊊
(䊊) Good, () general, (×) not good.
higher than ones of above two-type actuators, so large area efficiency can be obtained. In order to solve the key problem of piezo mechanism micromachining, a novel planer fabrication method of piezoactuator was developed by Suzuki [6]. In this paper, a complex fabrication technique for piezodriven XY-microstage with mechanical machining method and processing method of semiconductors has been withal proposed. The mechanical machining method includes dicing and femtosecond laser cutting. The processing method of semiconductors includes patterning of thick SU-8 layer, electroplating of nickel and removal of SU-8 mould by excimer laser [7] or special solution.
Fig. 1. The displacement enlarging principle of: (a) outside-driven and (b) inside-driven parallelogram mechanism.
1.1. Structure of piezodriven XY-microstage Three kinds of plane mechanisms of XY-microstage, outside-driven parallelogram mechanism, inside-driven parallelogram mechanism and four-parallelogram hinge mechanism are proposed as shown Fig. 1. The parallelogram mechanism is consisting of 8 sides and 16 flexure hinges, and its one corner is fixed, the opposite corner is to drive the stage for mounting of storage media. The outside-driven and inside-driven parallelogram mechanisms are driven by piezoactuators through the outside-levers and the inside inside-levers. In Fig. 1(c), the media stage is supported by four-parallelogram hinge, and driven by piezoactuators through double strings for enlarging of displacement. The main advantages over past mechanism are better linearity and precision for positioning, larger enlarging ratio of displacement, and higher area efficiency for the data storage. Figs. 2–4 are show the three kinds of XY-microstage structures based on above of the three kinds of mechanisms, respectively. In Fig. 2, the first kind structure has the largest enlarging ratio of displacement because of two times of displacement enlarging, but the area efficiency is poor compared with other two kinds one. In Fig. 3, the second kind structure has the highest of the area efficiency, over 60%, and has a possibility of rotating of the whole structure by mounting of four piezodriven legs at the four corner of the structure. In Fig. 4, the last kind structure has the best of displacement accuracy because of media stage supported by
Fig. 2. A piezodriven XY-microstage with outside-driven parallelogram mechanism.
Fig. 3. A piezodriven XY-microstage with inside-driven parallelogram mechanism.
232
D. Zhang et al. / Sensors and Actuators A 108 (2003) 230–233
Fig. 4. A piezodriven XY-microstage with four-parallelogram hinge mechanism.
a. PZT plate
e. Sputter and electroplating
b. Dicing
f. Dicing
c. SU-8
g. Repeats above processes
d. Development
h. Removal of SU-8
Fig. 5. A flow chart of the microfabrication process.
four-parallelogram hinge, and has larger area efficiency, over 50%.
Fig. 6. Prototypes of piezodriven XY-microstage.
2. Fabrication method and prototype The XY-microstages are made all from one PZT plate as shown Fig. 5. The piezoactuators are fabricated by dicing of grooves, electroplating and insulating of inner electrodes, sputtering of outer electrode. The through holes are machined by femtosecond laser cutting or SU-8 resist patterning. The levers are formed by nickel electroplating. In order to validate feasibility of the XY-microstage structures, we made two kinds of structures by femtosecond laser machining on nickel plate and assembling of PZT-actuators as shown in Fig. 6. The XY-displacements are 19 and 26 m at 150 V in outside-driven and inside-driven parallelogram mechanism, respectively. The theoretical enlarge ratios of the prototypes are 30 and 5, but actual enlarge ratios are 6 and 4.8 in the both mechanisms. Therefore the system deformation of the outside-driven mechanism is larger than one of inside-driven parallelogram mechanism. The displacement of XY-microstage is measured by scanning of AFM probe to nanoscale above the stage as shown Fig. 7. The measure results show that the XY-stage prototypes have a good linearity of displacement. The displacement signal can be used to control the multiprobe recording. The nanoscales can be patterned onto the stage by nano elec-
Fig. 7. The measurement method and results of inside-driven parallelogram mechanism displacement.
D. Zhang et al. / Sensors and Actuators A 108 (2003) 230–233
tron beam lithography, and the piezoresistive probes can be mounted on multiprobe array plate to measure the XY-stage displacement.
3. Conclusion Piezodriven XY-microstage can be fabricated by planer fabrication method in one PZT plate. The inside-driven parallelogram mechanism and four-parallelogram hinge mechanism driven by piezo-actuator have very large area efficiency. It has been validated that the system rigidity of inside-driven parallelogram mechanism is stronger than one of outside-driven parallelogram mechanism, and its fabrication processes are simpler.
References [1] D.W. Lee, T. Ono, T. Abe, M. Esashi, Microprobe array with electrical interconnection for thermal imaging and data storage, J. Microelectromech. Syst. 11 (2002) 215–221. [2] http://csns.snu.ac.kr/. [3] http://www.maschinenbau.tu-ilmenau.de/mb/wwwmm/aindex-e.htm/. [4] J.J. Choi, H. Park, K.Y. Kim, J.U. Jeon, Electromagnetic micro X–Y stage with very thick Cu coil for probe-based mass data storage device, Proc. SPIE 4334 (2001) 363–371. [5] Z.L. Zhang, N.C. Macdonald, Compound Stage MEM Actuator Suspended for Multidimensional Motion, US Patent No. 5,536,988 (1996). [6] G. Suzuki, M. Esashi, Planer Fabrication Multilayer Piezoelectric Actuator by Groove Cutting and Electroplating, in: Proceedings of the 13th IEEE MEMS’2000, Technical Digest, Miyazaki, Japan, 2000, pp. 46–51. [7] M.K. Ghantasala, J.P. Hayes, E.C. Harvey, D.K. Sood, Patterning, electroplating and removal of SU-8 moulds by excimer laser micromachining, J. Micromech. Microeng. 11 (2001) 133–139.
233
Biographies Deyuan Zhang was born in 1963 in Jilin, China. He received the BE and ME degrees in mechanical engineering from the Jilin University of Technology, China in 1984 and 1987 and the PhD degree in manufacture engineering from Beijing University of Aeronautics and Astronautics (BUAA), China in 1993. He served as an assistant and lecturer at the Department of Mechanical Engineering, Jilin University of Technology from 1987 to 1990 and associate professor at the Department of Manufacture Engineering, BUAA from 1993 to 1997. Since 1997 he has been a professor at the School of Mechanical Engineering and Automation in BUAA and a director of the Department of Mechanical Engineering in BUAA. His current research direction is micro/nano/bio manufacturing with ultrasonic, microorganism and MEMS. He is a member of the Academic Committee of BUAA and a member of the American Institute of Ultrasound in Medicine (AIUM). Takahito Ono received the BS degree in 1990 in physics from Hirosaki University, MS degree in 1992 in physics from Tohoku University and PhD degree in 1996 in mechatronics and precision engineering, Tohoku University. From 1996 to 1999 he has been a research associate and since 1999, he has been an associate professor in the Department of Mechatronics and Precision Engineering, Tohoku University. His research interests are in nano-fabrication and nano-mechatronics. Masayoshi Esashi was born in Sendai, Japan, on 30 January 1949. He received the BE degree in electronic engineering in 1971 and the PhD degree in 1976 at Tohoku University. From 1976 to 1981, he served as a research associate at the Department of Electronic Engineering, Tohoku University and he was an associate professor from 1981 to 1990. He has been a professor at the Department of Mechatronics and Precision Engineering from 1990 to 1998. Since 1998 he has been a professor at the New Industry Creation Hatchery Center in Tohoku University. He was a director of the Venture Business Laboratory in Tohoku University and an associate director of the Semiconductor Research Integrated from 1996 to 1998. He has been studying microsensors and integrated microsystems fabricated with micromachining. His current research topic is a microtechnology for saving energy and natural resources. He is a member of the IEEE and the IEE of Japan.
A piezodriven XY-microstage for multiprobe nanorecording Deyuan Zhang a,∗ , Chienliu Chang b , Takahito Ono b , Masayoshi Esashi c a
Department of Mechanical Engineering and Automation, Beihang University, Beijing 100083, China Faculty of Engineering, Tohoku University, 01 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan New Industry Creation Hatchery Center, Tohoku University, 01 Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan b
c
Received 29 July 2002; received in revised form 9 May 2003; accepted 5 June 2003
Abstract The properties of electrostatic, electromagnetic and piezoelectric actuators used for XY-microstage are compared to indicate high area efficiency but no good machinability of piezoelectric actuator, so that a novel planer fabrication method of the piezodriven XY-microstage with one PZT plate has been proposed. This fabrication method includes three processes, dicing, electroplating, femtosecond laser machining and so no. A parallelogram mechanism with flexure hinges, lever mechanisms and piezoelectrical actuators has been designed to make XY-displacement in monolayer plane structure. The area efficiency and volume efficiency of piezodriven XY-microstage are very higher than electrostaticdriven and electromagneticdriven one. The relationship of displacement characteristics with the sizes of parallelogram mechanism has been tested with the several principium prototypes fabricated by femtosecond laser machining of single nickel plate and assembly of PZT actuator. The test results show that the flexure hinges the shorter, the accuracy of the XY-displacement the better. Thirty micrometer displacement and 50% and above area efficiency have been obtained in the principium prototype. © 2003 Elsevier B.V. All rights reserved. Keywords: XY-stage; PZT; Multiprobe nanorecording
1. Introduction Magnetic and optical storage are approaching its physical limits due to the super-paramagnetic effect and the limitation of light diffraction, respectively. In Venture Business Laboratory of Tohoku University, a multi-heater-probe nanorecording system for application of ultra high density data storage beyond 1 Tbit/in.2 (25 nm bit) recording density was developed by means of a novel batch-fabrication method, and the near-field optical probe and focused electron beam probe for noncontact data storage were investigated, and the probes with a sub-100 nm heater were arrayed onto a glass substrate on 100 m centers [1]. The recording range of one probe in a disk is a 100 m × 100 m area. The bits are recorded onto the area on a several nanometer centers. Therefore a XY-microstage with 100 m × 100 m displacement range and nanometer resolution must be developed for driving of the high-density data storage disk. Up to now, the developed XY-microstages in the world were driven most by electrostatic actuator or electromagnetic actuator [2–5]. There is few or no piezodriven ∗ Corresponding author. Tel.: +86-10-8231-5654; fax: +86-10-8231-6603. E-mail address: [email protected] (D. Zhang).
0924-4247/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0924-4247(03)00373-X
XY-microstage because piezoelectric material is very difficult to micromachine by means of processing method of semiconductors. The PZT actuators are usually applied to larger XY-stage by means of assembling process. The properties of electrostatic, electromagnetic and piezoelectric actuators used for XY-microstage are compared as shown in Table 1. In the case of electrostatic type stage, the processing method of semiconductors can be used, so that this type of actuator is applied most widely for MEMS field, but the area efficiency of electrostatic XY-stage for the data storage is very poor because of low driven force, small displacement, careful insulation and a lot of comb probes. Usually the area efficiency of electrostatic XY-stage is less than 5%. Therefore it is at great disadvantage for miniaturization of whole multiprobe nanorecording system. In the case of electromagnetic type stage, the area efficiency and displacement range for the data storage are larger than ones of electrostatic type stage, but the volume and weight of whole stage are very large, and the assembling process of several permanent magnet is required in fabrication process. So that it is also at disadvantage for miniaturization of whole multiprobe nanorecording system. In the case of piezoelectric type stage, the volume power and the displacement accuracy of piezoactuator are very
D. Zhang et al. / Sensors and Actuators A 108 (2003) 230–233
231
Table 1 Comparison of typical actuators Properties
Actuators Electrostatic
Electromagnetic
Piezoelectric
Volume power Area efficiency Volume efficiency Machinability Displacement Frequency response Displacement accuracy
× ×
× ×
䊊 䊊 䊊
䊊
×
䊊
× ×
䊊 䊊
(䊊) Good, () general, (×) not good.
higher than ones of above two-type actuators, so large area efficiency can be obtained. In order to solve the key problem of piezo mechanism micromachining, a novel planer fabrication method of piezoactuator was developed by Suzuki [6]. In this paper, a complex fabrication technique for piezodriven XY-microstage with mechanical machining method and processing method of semiconductors has been withal proposed. The mechanical machining method includes dicing and femtosecond laser cutting. The processing method of semiconductors includes patterning of thick SU-8 layer, electroplating of nickel and removal of SU-8 mould by excimer laser [7] or special solution.
Fig. 1. The displacement enlarging principle of: (a) outside-driven and (b) inside-driven parallelogram mechanism.
1.1. Structure of piezodriven XY-microstage Three kinds of plane mechanisms of XY-microstage, outside-driven parallelogram mechanism, inside-driven parallelogram mechanism and four-parallelogram hinge mechanism are proposed as shown Fig. 1. The parallelogram mechanism is consisting of 8 sides and 16 flexure hinges, and its one corner is fixed, the opposite corner is to drive the stage for mounting of storage media. The outside-driven and inside-driven parallelogram mechanisms are driven by piezoactuators through the outside-levers and the inside inside-levers. In Fig. 1(c), the media stage is supported by four-parallelogram hinge, and driven by piezoactuators through double strings for enlarging of displacement. The main advantages over past mechanism are better linearity and precision for positioning, larger enlarging ratio of displacement, and higher area efficiency for the data storage. Figs. 2–4 are show the three kinds of XY-microstage structures based on above of the three kinds of mechanisms, respectively. In Fig. 2, the first kind structure has the largest enlarging ratio of displacement because of two times of displacement enlarging, but the area efficiency is poor compared with other two kinds one. In Fig. 3, the second kind structure has the highest of the area efficiency, over 60%, and has a possibility of rotating of the whole structure by mounting of four piezodriven legs at the four corner of the structure. In Fig. 4, the last kind structure has the best of displacement accuracy because of media stage supported by
Fig. 2. A piezodriven XY-microstage with outside-driven parallelogram mechanism.
Fig. 3. A piezodriven XY-microstage with inside-driven parallelogram mechanism.
232
D. Zhang et al. / Sensors and Actuators A 108 (2003) 230–233
Fig. 4. A piezodriven XY-microstage with four-parallelogram hinge mechanism.
a. PZT plate
e. Sputter and electroplating
b. Dicing
f. Dicing
c. SU-8
g. Repeats above processes
d. Development
h. Removal of SU-8
Fig. 5. A flow chart of the microfabrication process.
four-parallelogram hinge, and has larger area efficiency, over 50%.
Fig. 6. Prototypes of piezodriven XY-microstage.
2. Fabrication method and prototype The XY-microstages are made all from one PZT plate as shown Fig. 5. The piezoactuators are fabricated by dicing of grooves, electroplating and insulating of inner electrodes, sputtering of outer electrode. The through holes are machined by femtosecond laser cutting or SU-8 resist patterning. The levers are formed by nickel electroplating. In order to validate feasibility of the XY-microstage structures, we made two kinds of structures by femtosecond laser machining on nickel plate and assembling of PZT-actuators as shown in Fig. 6. The XY-displacements are 19 and 26 m at 150 V in outside-driven and inside-driven parallelogram mechanism, respectively. The theoretical enlarge ratios of the prototypes are 30 and 5, but actual enlarge ratios are 6 and 4.8 in the both mechanisms. Therefore the system deformation of the outside-driven mechanism is larger than one of inside-driven parallelogram mechanism. The displacement of XY-microstage is measured by scanning of AFM probe to nanoscale above the stage as shown Fig. 7. The measure results show that the XY-stage prototypes have a good linearity of displacement. The displacement signal can be used to control the multiprobe recording. The nanoscales can be patterned onto the stage by nano elec-
Fig. 7. The measurement method and results of inside-driven parallelogram mechanism displacement.
D. Zhang et al. / Sensors and Actuators A 108 (2003) 230–233
tron beam lithography, and the piezoresistive probes can be mounted on multiprobe array plate to measure the XY-stage displacement.
3. Conclusion Piezodriven XY-microstage can be fabricated by planer fabrication method in one PZT plate. The inside-driven parallelogram mechanism and four-parallelogram hinge mechanism driven by piezo-actuator have very large area efficiency. It has been validated that the system rigidity of inside-driven parallelogram mechanism is stronger than one of outside-driven parallelogram mechanism, and its fabrication processes are simpler.
References [1] D.W. Lee, T. Ono, T. Abe, M. Esashi, Microprobe array with electrical interconnection for thermal imaging and data storage, J. Microelectromech. Syst. 11 (2002) 215–221. [2] http://csns.snu.ac.kr/. [3] http://www.maschinenbau.tu-ilmenau.de/mb/wwwmm/aindex-e.htm/. [4] J.J. Choi, H. Park, K.Y. Kim, J.U. Jeon, Electromagnetic micro X–Y stage with very thick Cu coil for probe-based mass data storage device, Proc. SPIE 4334 (2001) 363–371. [5] Z.L. Zhang, N.C. Macdonald, Compound Stage MEM Actuator Suspended for Multidimensional Motion, US Patent No. 5,536,988 (1996). [6] G. Suzuki, M. Esashi, Planer Fabrication Multilayer Piezoelectric Actuator by Groove Cutting and Electroplating, in: Proceedings of the 13th IEEE MEMS’2000, Technical Digest, Miyazaki, Japan, 2000, pp. 46–51. [7] M.K. Ghantasala, J.P. Hayes, E.C. Harvey, D.K. Sood, Patterning, electroplating and removal of SU-8 moulds by excimer laser micromachining, J. Micromech. Microeng. 11 (2001) 133–139.
233
Biographies Deyuan Zhang was born in 1963 in Jilin, China. He received the BE and ME degrees in mechanical engineering from the Jilin University of Technology, China in 1984 and 1987 and the PhD degree in manufacture engineering from Beijing University of Aeronautics and Astronautics (BUAA), China in 1993. He served as an assistant and lecturer at the Department of Mechanical Engineering, Jilin University of Technology from 1987 to 1990 and associate professor at the Department of Manufacture Engineering, BUAA from 1993 to 1997. Since 1997 he has been a professor at the School of Mechanical Engineering and Automation in BUAA and a director of the Department of Mechanical Engineering in BUAA. His current research direction is micro/nano/bio manufacturing with ultrasonic, microorganism and MEMS. He is a member of the Academic Committee of BUAA and a member of the American Institute of Ultrasound in Medicine (AIUM). Takahito Ono received the BS degree in 1990 in physics from Hirosaki University, MS degree in 1992 in physics from Tohoku University and PhD degree in 1996 in mechatronics and precision engineering, Tohoku University. From 1996 to 1999 he has been a research associate and since 1999, he has been an associate professor in the Department of Mechatronics and Precision Engineering, Tohoku University. His research interests are in nano-fabrication and nano-mechatronics. Masayoshi Esashi was born in Sendai, Japan, on 30 January 1949. He received the BE degree in electronic engineering in 1971 and the PhD degree in 1976 at Tohoku University. From 1976 to 1981, he served as a research associate at the Department of Electronic Engineering, Tohoku University and he was an associate professor from 1981 to 1990. He has been a professor at the Department of Mechatronics and Precision Engineering from 1990 to 1998. Since 1998 he has been a professor at the New Industry Creation Hatchery Center in Tohoku University. He was a director of the Venture Business Laboratory in Tohoku University and an associate director of the Semiconductor Research Integrated from 1996 to 1998. He has been studying microsensors and integrated microsystems fabricated with micromachining. His current research topic is a microtechnology for saving energy and natural resources. He is a member of the IEEE and the IEE of Japan.