Influence of Specimen Size and Sub-Micron Notch on The Fracture Behavior of Single Crystal Silicon Microelements and Nanoscopic Afm Damage Evaluation

1998 ◽  
Vol 546 ◽  
Author(s):  
Kohji Minoshima ◽  
Shigemichi Inoue ◽  
Tomota Terada ◽  
Kenjiro Komai

AbstractSimple bending tests of single-crystal silicon microelements fabricated by photoetching were performed. Silicon microelements deform elastically until final catastrophic failure, showing a brittle nature. The fracture strength increases with a decrease in specimen size, and the maximum strength reaches about 8 GPa. A Focused ion beam was used to machine a sub-µm deep notch. Such a small notch decreases the fracture strength of a microelement. Some fatigue tests were conducted in laboratory air and in distilled water: water reduces the strength of microelement under fatigue loading. Fracture surface and sample surface were closely examined with a scanning electron microscope and an atomic force microscope, and the fracture mechanisms are discussed from the nanoscopic points of view.

2020 ◽  
Vol 40 (12) ◽  
pp. 1222001
Author(s):  
宋辞 Song Ci ◽  
田野 Tian Ye ◽  
石峰 Shi Feng ◽  
张坤 Zhang Kun ◽  
沈永祥 Shen Yongxiang

Author(s):  
V. S. Kovivchak ◽  
T. V. Panova ◽  
O. V. Krivozubov ◽  
N. A. Davletkil’deev ◽  
E. V. Knyazev

2005 ◽  
Vol 297-300 ◽  
pp. 292-298 ◽  
Author(s):  
Satoru Koyama ◽  
Kazuki Takashima ◽  
Yakichi Higo

Reliability is one of the most critical issues for designing practical MEMS devices. In particular, the fracture toughness of micro-sized MEMS elements is important, as micro/nano-sized flaws can act as a crack initiation sites to cause failure of such devices. Existing MEMS devices commonly use single crystal silicon. Fracture toughness testing upon micro-sized single crystal silicon was therefore carried out to examine whether a fracture toughness measurement technique, based upon the ASTM standard, is applicable to 1/1000th sized silicon specimens. Notched cantilever beam type specimens were prepared by focused ion beam machining. Two specimens types with different notch orientations were prepared. The notch plane/direction were (100)/[010], and (110)/[ _ ,110], respectively. Fracture toughness tests were carried out using a mechanical testing machine for micro-sized specimens. Fracture has been seen to occur in a brittle manner in both orientations. The provisional fracture toughness values (KQ) are 1.05MPam1/2 and 0.96MPam1/2, respectively. These values meet the micro-yielding criteria for plane strain fracture toughness values (KIC). Fracture toughness values for the orientations tested are of the same order as values in the literature. The results obtained in this investigation indicate that the fracture toughness measurement method used is applicable for micro-sized components of single crystal silicon in MEMS devices.


2006 ◽  
Vol 960 ◽  
Author(s):  
Warren MoberlyChan

ABSTRACTIon beams have been used to modify surface topography, producing nanometer-scale modulations (and even subnanometer ripples in this work) that have potential uses ranging from designing self-assembly structures, to controlling stiction of micromachined surfaces, to providing imprint templates for patterned media. Modern computer-controlled Focused Ion Beam tools enable alternating submicron patterned zones of such ion-eroded surfaces, as well as dramatically increasing the rate of ion beam processing. The DualBeam FIB/SEM also expedites process development while minimizing the use of materials that may be precious (Diamond) and/or produce hazardous byproducts (Beryllium). A FIB engineer can prototype a 3-by-3-by-3 matrix of variables in tens of minutes and consume as little as zeptoliters of material; whereas traditional ion beam processing would require tens of days and tens of precious wafers. Saturation wavelengths have been reported for ripples on materials such as single crystal silicon or diamond (∼200nm); however this work achieves wavelengths >400nm on natural diamond. Conversely, Be can provide a stable and ordered 2-dimensional array of <40nm periodicity. Also ripples <0.4nm are fabricated on carbon-base surfaces, and these quantized picostructures are measured by HR-TEM and electron diffraction. Rippling is a function of material, ion beam, and angle; but is also controlled by chemical environment, redeposition, and aspect ratio. Ideally a material has a constant yield (atoms sputtered off per incident ion); however, pragmatic FIB processes, coupled with the direct metrological feedback in a DualBeam tool, reveal etch rates do not remain constant for nanometer-scale processing. Control of rippling requires controlled metrology, and robust software tools are developed to enhance metrology. In situ monitoring of the influence of aspect ratio and redeposition at the micron scale correlates to the rippling fundamentals that occur at the nanometer scale and are controlled by the boundary conditions of FIB processing.


1991 ◽  
Vol 226 ◽  
Author(s):  
C.C. Chao ◽  
R. Chleboski ◽  
E.J. Henderson ◽  
C.K. Holmes ◽  
J.P. Kalejs ◽  
...  

AbstractThe fracture twist test is used to obtain the statistical fracture strength distribution for 10-cm square single crystal and polycrystalline silicon wafers cut with a high-power Nd:YAG laser. Tensile wafer edge stresses at fracture are calculated using nonlinear finite element analysis, and the model results are used to examine the limitations of linear torsion and plate theories. The basic hypothesis is that fracture strength of laser-cut wafers is limited by microcracks formed by large residual tensile stresses produced in the cut edge upon cooling after cutting. Differences are found between single crystal CZ and polycrystalline EFG silicon material Weibull parameters characterizing the fracture strength distribution. These indicate that there is a statistical influence of material variables on the fracture strength of the EFG silicon, which lowers its strength and increases the variance of fracture response in comparison to single crystal silicon.


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