In the 1980's science and technology have pushed towards miniaturization. In order to interface to the microscopic world, miniaturized structures are necessary to bridge the gap to the macroscopic world. Well established and developed methods of micro fabrication applications such as the fabrication of micro structures and circuits can used to micromachine structures in 3D indispensible to interface to the nano world. Micromachining has great significance industrial application such as the accelerometer that triggers air bags in cars and mass storage devices. Bulk materials in micro fabrication are shaped into microstructures using lithography and etching. Different kinds of chemical solutions including acids and bases were used to selectively remove significant amount of silicon from a silicon wafer by chemical reaction of the silicon with the etchant could formed micro structures. Because of the undercutting, etched pits are usually quite different forms the mask at the corners of the structures. The undercutting of convex corners can be compensated by designing suitable mask. By using compensation methods sharp corners can be constructed. Different research group proposed and demonstrated various corner compensation designs using KOH, EDP and TMAH solution. Although other methods have also been reported, they use extra mask and processing steps, which make them more expensive and complex.

1. Chii-Rong Yang, Po-Ying Chen, Cheng-Hao YangYuang-Cherng Chiou and Rong-Tsong Lee. 2005. Effects of various ion-typed surfactants on silicon anisotropic etching properties in KOH and TMAH solutions, Sensors and Actuators A 119. 271–281.
2. K. Biswas and S. Kal. 2006. Etch characteristics of KOH, TMAH and dual doped TMAH for bulk micromachining of silicon, Microelectronics Journal 37. 519–525.
3. David Craven, Imaging and Resist Technologies for the Micromachining Industry. 1996. SPIE Micromachining & Microfabrication Symposium.
4. Duan, Xuefeng. 2005. Microfabrication Using Bulk Wet Etching with TMAH.
5. Ernest Bassous. 1978. Fabrication of novel Three-Dimensional microstructures by anisotropic etching of (100) and (110) Silicon, IEEE transaction on electron devices. No. 10
6. Irena Zubel, Irena Barycka, Kamilla Kotowska and Magorzata Kramkowska. 2001. Silicon anisotropic etching in alkaline solutions IV The effect of organic and inorganic agents on silicon anisotropic etching process, Sensors and Actuators A 87. 163-171.
7. Irena Zubel. 2000. Silicon anisotropic etching in alkaline solutions III: On the possibility of spatial structures forming in the course of Si (100) anisotropic etching in KOH and KOH+IPA solutions, Sensors and Actuators 84. 116–125.
8. Jae Sung You, Donghwan Kim, Joo Youl Huh, Ho Joon Park, James Jungho Pak and Choon Sik Kang. 2001. Experiments on anisotropic etching of Si in TMAH, Solar Energy Materials & Solar Cells 66. 37-44.
9. Kenji Tokoro, Daisuke Uchikawa, Mitsuhiro Shikinda and Kazuo Sato. 1998. Anisotropic etching properties of silicon in KOH and TMAH, IEEE 1998 .
10. Kenneth E. Bean. 1978. Anisotropic Etching of Silicon, IEEE transations on electron devices, VOL. ED-25
11. Mitsuhiro Shikida , Kazuo Sato, Kenji Tokoro and Daisuke Uchikawa. 2000. Differences in anisotropic etching properties of KOH and TMAH solutions, Sensors and Actuators 80. 179–188.
12. Mitsuhiro Shikida, Kazuo Sato, Kenji Tokoro and Daisuke Uchikawa. 1999. Comparison of anisotropic etching properties between KOH and TMAH solutions.
13. Nadim Maluf and Kirt Williams. 1999. An Introduction to Microelectromechanical Systems Engineering.
14. Osamu Tabata, Ryoup Asahl, Hirofumf Funabashi, Keuchi Shimaoka and Susumu Sugfyama. 1992. Anisotropic etching of silicon in TMAH solutions, Sensors and Actuators A 34. 51-57
15. Ping-Hei Chen, Hsin-Yah Peng, Chia-Ming Hsieh and Minking K. Chyu. 2001. The characteristic behavior of TMAH water solution for anisotropic etching on both silicon substrate and SiO2 layer, Sensors and Actuators A 93.
16. Prem Pal, Kazuo Satoa, Mitsuhiro Shikidaa and Miguel A. Gosálvezb. 2009. Study of corner compensating structures and fabrication of various shapes of MEMS structures in pure and surfactant added TMAH, Sensors and Actuators A 154. 192–203.
17. D. Resnik, D. Vrtacnik, U. Aljancic and S. Amon. 2000. Wet etching of silicon structures bounded by (311) sidewalls, Microelectronic Engineering 51–52. 555–566.
18. H. Seidel, L Csepregi, A Heeuberger and H. Boumgartel. 1990. Anisotropic etching of crystalline silicon in alkaline solutions, J. Electrochem. Soc, vol. 137
19. E. vav Veenendaal, K. Sato, M. Shikinda and J. van suchtelen. 2001. Micromorphology of single crysylline silicon surfaces during anisotropic wet chemical etching in KOH and TMAH Sensors and Actuators A, 93. 219-231.
20. Wei Fan and Dacheng Zhang. 2006. A Simple Approach to Convex Corner Compensation for KOH Anisotropic Etching on (100) Silicon Wafer, Journal of Micromechanics and Microengineering .

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