Study On Thermal Stress Effect Of Monocrystal Silicon Interacted With Long Pulse Laser

Monocrystalline silicon as an excellent semiconductor can be used for the base material and conducting material of photoelectron components but will lead to the failure of component's normal operation once damage.Monocrystalline silicon is prone to breakage,melting,ablation and other damages under laser action,mainly because monocrystalline silicon can absorb laser energy so that thermal stress would be generated due to uneven distribution of interior temperature.Thus this article carries out studies as below on the damaging process of monocrystalline silicon's thermal stress conducted under long-pulse laser action:Theoretically,based on thermal conduction theory and elastic mechanics theory,establish a long-pulse laser monocrystalline silicon interaction 2D axial symmetry simulation model,analyze the temperature change of monocrystalline silicon's central point,axial direction,and radial direction at the pulse width of 3ms,energy density of 124.21J/cm2,159.23J/cm2,222.93J/cm2,254.78J/cm2,and 286.62J/cm2 respectively,then obtain the change rule of monocrystalline silicon's temperature field with the variation of energy density and pulse width;analyze the axial stress and radial stress of monocrystalline silicon at the pulse width of 3ms,energy density of 7.96J/cm2,10.75J/cm2 and 15.13J/cm2 respectively,and obtain the change rule of monocrystalline silicon's stress field with the variation of energy density and pulse width.Experimentally,build an experimental system of monocrystalline silicon's temperature damage under long-pulse laser action,and obtain the change rule of monocrystalline silicon superficial stress field with the variation of energy density and pulse width.Apply the method of Mach-Zehnder interference,build an experimental system of monocrystalline silicon's real-time stress damage under long-pulse laser action.Meanwhile,use high-speed camera and optical interference system to convert the material superficial deformation into the transformation of interference stripe,and then obtain the stress-strain corresponding relation through conversion of interference stripe result,so as to work out the variation relation of monocrystalline silicon's stress field with the changing of energy density and pulse width.Make comparison analysis on temperature field and stress field obtained in experiments with temperature field and stress field obtained in simulation,and find that when the pulse width is fixed,temperature field and stress field in both experiments and simulation will increase with the increasing of energy density;when the energy density is fixed,both temperature field and stress field in experiments and simulation will decrease with the increasing of pulse width.Experiments and simulation have shown the same change rule.Carry out the experimental studies on monocrystalline silicon's damage morphologies induced by laser,obtain the change rule of monocrystalline silicon's damage depth and area with laser energy density and pulse width,and then make analysis on the breakage,fusion,ablation and other phenomena occurred on monocrystalline silicon's surface.