Vol1 29,No1 4,pp Spectroscopy and Spectral Analysis April, 2009 DRAM. : O65713 : A DOI: / j1issn (2009)

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1 2 9, 4 Vol1 29,No1 4,pp Spectroscopy and Spectral Analysis April, 2009 DRAM 1, 2, 2, 2 1., , ( FTIR) (DRAM),,, DRAM,, ; ; ; : O65713 : A DOI: / j1issn (2009) ,, [2, 5, 6 ] 1 (microelectromechanical system, MEMS), [123 ],,, ;,,, / (ultravi2, ; olet/ visible spectroscopy, UV/ Vis), (scanning electron microscope, SEM) [4 ] 1 (atomic force microscope, A FM), ( Fourier transform infrared reflectance, FTIR) (dynamic random access memory, DRAM),, Fig11 FTIR measurement system flowchart,, FTIR,, : , : : 863 (2006AA04Z325), ( ) (NCET ) :, 1970, e2mail : hust1edu1cn

2 936 29, [7, 8 ] Maxwell2Garnett, Maxwell2Gar2 nett (1) - h + 2 N = h f j j j = 1 j - h, + 2 h j = 1 f j = 1 (1), h, f j j, j j, j N, j 1 N, ( Fresnel) [9 ] (2) M11 M21 M12 M22 = D - 1 N 0 l = 1 r R Dl P ld - l 1 D s (2), 1, 90, 9,, 2,, 7, 3, 90,, 45 10, 4, 8, 5, 90, 12,, 6 90,, MCT r = M21, R = r 2 (3) M11 D0, Ds, Dl l, Pl l (1), (2) (3),, Levenberg2Marquardt (L M),,, [10, 11 ],, ,, ; ;,, ;,,, Newport MIR8025, 11728m, MCT(mercury cadmium telluride) 212 3,,,, 4,,,,,,,,,, 5 Zem2 ax, 015,, 017

3 4 937 mm, 200m 600m, 3 FTIR, SEMI, 200 mm, 1 mm 3m, 90 nm,, 7,, [12,13 ],,,,, [14,15 ] Fig1 7 FTIR reflectance spectrum from the measurement of the sample 6 45, 90-45, 3, - 015, ,, 45,,, 45,,, 8, 4, Fig18 Sample with trench structures and the corresponding equivalent theory model Fig16 The focus situation with different beam incidence angle of 45, 90 and - 45 ( Fresnel)

4 938 29, Levenberg2Marquardt (L M),,,, 9, 1, F TIR SEM, 1 % Table 1 Parameters measured by SEM and FTIR /m SEM F TIR / % Fig19 The f itting of the reflectance spectra from measurement and theoretical model : Measurement ; : Theoretical model DRAM,,,, [ 1 ] Witt mann J, Kupfer C. Journal of t he Electrochemical Society, 2005, 152 (2) : G148. [ 2 ] Rudolph U, Weikmann E, Kinne A, et al. Proceedings of 2004 IEEE/ SEMI Advanced Semiconductor Manufacturing Conference and Workshop, [ 3 ] Kibe M, Sakai T, Ohiwa T, et al. Proceedings of 2003 IEEE International Symposium on Semiconductor Manufacturing, [ 4 ] Ram P, Ant hony P, Ophir D. Proceedings of SPIE, 2002, 4689 : [ 5 ] Zaidi S, Stojakovic G, Gut mann A, et al. Proceedings of SPIE, 2003, 5038 : 185. [ 6 ] Wang Xiaodong, Zeng Wanxue, Lu Guoping, et al. Journal of Vacuum Science and Technology B, 2007, B25 (4) : [ 7 ] Jellison G E. Handbook of Silicon Semiconductor Metrology. New York : Marcel2Dekker, Inc., [ 8 ] Weidner A, Slodowskib M, Halm C, et al. Proceedings of SPIE, 2004, 5375 : 232. [ 9 ] Yeh P. Optical Waves in Layered Media. New York : John Wiley & Sons, Inc, [ 10 ] ZHU J un, L IU Wen2qing, L IU Jian2guo, et al (,,, ). Spectroscopy and Spectral Analysis( ), 2005, 25 (10) : [ 11 ] CHEN G Biao, WU Xiao2hua, CHEN De2zhao (,, ). Spectroscopy and Spectral Analysis ( ), 2006, 26 (10) : [ 12 ] ZHAN G Tian2shu, L IU Wen2qing, GAO Min2guang, et al (,,, ). Spectroscopy and Spectral Analysis( ), 2006, 26 (3) : 430. [ 13 ] L I Qing2bo, ZHAN G Guang2jun, XU Ke2xin, et al (,,, ). Spectroscopy and Spectral Analysis( ), 2007, 27 (8) : [ 14 ] Zhang Chuangwei, Liu Shiyuan, Shi Tielin, et al. Proceedings of 3rd. IEEE International Conference on Nano/ Micro Engineered and Mo2 lecular Systems, [ 15 ] Kessel T, Wickramasinghe H K. Optics Letters, 1999, 24 : 1702.

5 4 939 Model2Based FTIR Reflectometry Measurement System f or Deep Trench Structures of D RAM L IU Shi2yuan 1, ZHAN G Chuan2wei 2, SH EN Hong2wei 2, GU Hua2yong 2 1. State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan , China 2. Division of Optoelectronic Materials and Micro2Nano Manufacture, Wuhan National Laboratory for Optoelectronics, Wuhan , China Abstract A method and system for measuring deep trench structures of dynamic random access memory (DRAM) based on Fourier transform inf rared ( F TIR) reflectometry is proposed. The principle of the measurement system is presented, along with a detailed description of the optical path design. By regulating the slit aperture to decrease the size of the detection spot and opti2 mizing the incidence angle onto the wafer, the reflection f rom the backside of the wafer is suppressed, thus the signal2to2noise ra2 tio ( SNR) of the measurement is increased significantly. The experiment s carried out on the deep trench structures of DRAM demonstrate that the trench geometric parameters can be extracted with a nanometer scale accuracy using the proposed system, thus the technique is proven to provide a non2contact, nondestructive, time2effective, low2cost and high resolution tool for the measurement of deep trench structures. It is expected that the proposed technique will find potential applications in the on2line monitoring and process control for microelectronics and microelectromechanical system ( M EMS) manufacturing. Keywords FTIR spectrometer ; Infrared reflectance spectrum ; DRAM ; Deep trench structure (Received Oct. 8, 2007 ; accepted Jan. 12, 2008)