2000 Fiscal Year Final Research Report Summary
Nano-Defects Inspection in Polished Silicon Wafer Sub-Surface Using IR Evanescent Light
| Project/Area Number |
11450058
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
機械工作・生産工学
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| Research Institution | Osaka University |
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Principal Investigator |
TAKAYA Yasuhiro Osaka university, Department of Mechanical Engineering and Systems, Associate Professor, 大学院・工学研究科, 助教授 (70243178)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Satoru Osaka university, Department of Mechanical Engineering and Systems, Research Associate, 大学院・工学研究科, 助手 (30283724)
MIYOSHI Takashi Osaka university, Department of Mechanical Engineering and Systems, Professor, 大学院・工学研究科, 教授 (00002048)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Silicon wafer / Sub-surface / Nano-defect / COP / IR Laser / Evanescent Light / Probe tip / FDTD simulation |
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| Research Abstract |
Recently, the design rule of LSI device has been shrank rapidly and challenges to achieve finer scale than 0.1 micrometer are continuously carried out now. In order to realize high productivity and reliability in the fabrication process of such next generation devices, nano-defects inspection technology for polished Si wafer surface is essential. In this research, we propose the new inspection method of nano-defects in a polished Si wafer subsurface by detecting infrared radiation (IR) evanescent light emerging on the surface. IR evanescent light is detected using scanning probe tips and the resolution is independent of light wavelength. Therefore this method makes it possible to sensitively detect the nano-defects with the size of nano meter scale and the defects in subsurface as well as on the surface can be detected also.
Main results of this study are summarized as follows,
(1) Rigorous computer simulation method are established by means of Finite Difference Time Domain (FDTD) method
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based on Maxwell's equations. FDTD method can analyses electro-magnetic wave propagation with not only three dimensional space resolution but also time resolution.
(2) We have calculated the electromagnetic field of the simulation model consisting of the designed probe tip and the Si wafer. The Si and SiO_2 probe tip is approached towards the surface with a gap of 100nm. The IR (1064nm wavelength) light beam with s-polarized Gaussian wave reached at the Si wafer surface with incident angle at 45.0 degree exceeding the critical angle.
(3) In the near field zone, the disturbance of the evanescent light resulting from the external defects occurs around the defects. And the disturbance is picked up by the tip of the Si probe and propagated through the probe. These results suggest that the information of the small external defects with the sizes of 40nm can be detected by the Si probe.
(4) It can be seen that disturbance of the evanescent light resulting from the internal defect such as the voids defect is also picked up by the tip of the Si probe. This result suggests that even if the defect exists in the subsurface, this method enables the high sensitive detection of the defects with the sizes of 10nm scale.
(5) Position, size and features such as pit or boss of a defect can be estimated by analyzing detection signal obtained by scanning the probe tip on Si wafer surface.
(6) Material of probe tips is one of the important factors to detect the disturbance of the evanescent light resulting from a nano-defect on or below Si surface with high sensitivity. Silicon-oxide is more suitable material for the probe tip than Silicon in sensitivity. Less
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Research Products
(10 results)
