Investigation On The Bonding Method Of Quartz Devices Based On Femtosecond Laser

Quartz is widely used in Micro-Electro-Mechanical System(MEMS)devices,optoelectronic devices and microflow control devices due to its excellent thermal properties,mechanical properties,optical properties and chemical properties.The production of quartz devices involves the fabrication,combination and testing,among which the combination of components is completed by bonding.The devices are often influenced by processing conditions through traditional bonding methods.For example,the requirement of placing the device to be processed in a n environment with high temperature can cause irreversible damage to the internal structures of the devices.Besides,the bonding strength is not high enough so that limits the application range of the devices.A new effective bonding method is urgently needed.Therefore,this research topic study the bonding method of quartz devices by femtosecond laser,which is a novel method in the bonding technique.In this paper,the interaction between femtosecond laser and quartz is analyzed based on the theories of nonlinear optics and solid state physics.The process of the free electrons generation based on photoionization effect and avalanche ef fect is studied,and the heating process of the free electrons energy transfer to the lattice is analyzed,as well as the results of the modification of quartz material.The propagation model based on the laser pulse envelope transmission equation and the free electron density evolution equation is adopted,the flux of laser pulses in quartz material,the distribution of the free electron and the energy deposited are calculated.The contribution of nonlinear effects to energy deposition and the effect of di fferent processing parameters on energy deposition are also studied.The study proves that the Kerr effect has an important effect on the propagation of laser pulse,and the main mechanism of laser energy deposition into quartz is found by plasma absorptio n.The study also analyzes the effect of the numerical aperture on the energy deposition,When the numerical aperture is smaller,the longer the energy is distributed along the laser propagation axis.At the same time,the effect of single pulse energy on the internal effect of quartz is analyzed,and the larger the single pulse energy,the smaller the energy transmission rate,and the larger the effective area of pulse energy deposition.The experiments of bonding quartz device by femtosecond laser are carried out.In order to show the characteristics of the femtosecond laser in the modification area inside the quartz material,the cross sections of the processing quartz glass are corroded by hydrofluoric acid(HF),and the appearance of laser energy deposi tion inside the material can be revealed.The area of modification is mainly divided into two parts: one is the molten area and the other is the ablation area.Then,the effect of single pulse energy on the position of the affecting region is studied,and the larger the single pulse energy,the greater the position offset of the processing area.Under the influence of different laser parameters,such as the single pulse energy,scan velocity and repetition frequency,the effect of the shape and size of the processing area is studied.Finally,the process study of quartz glass bonding is carried out,and the sealing test is carried out on the device sample after bonding.