Three-dimensional mechanical stress analysis of trench isolation along {111} gliding planes

Three dimensional mechanical stress simulation has been applied to the trench isolation structure for bipolar LSIs. The accuracy of the simulation was confirmed by the micro Raman measurements of the actual trench structure. Considering the three dimensional analysis of the dislocation formation in the silicon crystal, there are 4 different {111} gliding planes at each point, and 3 specific gliding <110> directions for each {111} plane along which the dislocation of silicon occurs. Thus 12 gliding directions exist at each point. Resolved shear stresses along the 12 directions have been calculated by the simulation. The simulated results basically agree with the results of dislocation formation in the experiment. This method is a very useful tool to analyze the dislocation or defect formation along {111} gliding planes of the trench isolation structure.<
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