Rapid formation of high aspect ratio through holes in thin glass substrates using an engineered, QCW laser approach

Analysis and mitigation of stress induced by rapid formation of through glass vias in thin substrates

“…These permanent stresses will remain in the product unless relieved using a controlled annealing process. 35 As discussed in our earlier work 28 and also illustrated here in Figure 13, the high peak power of the picosecond laser pulses allows for multiphoton absorption to occur near the bottom surface. The high repetition rate of the laser results in heat accumulation inside the glass substrate over several microseconds until a threshold temperature is reached where linear absorption takes over due to the collapse of the glass bandgap at elevated temperatures.…”

“…Multi-physical simulations have been used previously to explore the ablation mechanism involved in the glass via drilling process using QCW laser pulses. 28 The simulation model was developed through a collaboration between MKS and the Technical University of Vienna (TU-Wien). 37,38 The simulation model takes into account the laser beam propagation to the work surface, the interaction of the laser beam with the target, as well as the fluid or gas flow when the material is melted or vaporized.…”

“…The simulation model has been previously applied to study the ultrafast laser processing with ∼GHz bursts in copper 39 and silicon, 40 as well as in our first publication on through-glass-via drilling. 28 A detailed description of the simulation model can be found in Ref. 28,[37][38][39]41 3.…”

“…28 A detailed description of the simulation model can be found in Ref. 28,[37][38][39]41 3. EXPERIMENTAL RESULTS Figure 5 shows a scanning electron microscope (SEM) image of a focused ion beam (FIB) milled and crosssectioned TGV using a ThermoFisher Nova Nano 200 dual beam system.…”

“…This is accomplished by using a high power, quasi-continuous wave (QCW), 515 nm laser with a simple Gaussian beam profile focusing scheme. 28,29 With this process, the laser light passes through a glass substrate with the beam waist set below the back surface of the glass substrate. After a few microseconds of incubation time, non-linear absorption initiated at the bottom glass/air interface transitions to a more linear absorption, and rapid ejection of the molten glass forms the through via.…”