Localized laser assisted eutectic bonding of quartz and silicon by Nd:YAG pulsed-laser

A localized laser assisted eutectic bonding process to bond 80 μm thick single crystal quartz chips to silicon substrates has been successfully developed and characterized. The two bond partners are bonded via intermediate layers of Cr, Au and Sn, with the composition of Au:Sn set close to 80:20 wt.%. Laser light source from the Nd:YAG Q-switched laser processing system with a wavelength of 355 nm, a spot diameter of 25 μm and variable power up to a maximum of 2 W is used as the energy source to initiate bonding at any user-defined region(s). Effects of important laser process parameters, such as laser power, scanning velocity and repetition rate on bond strength, interface quality and heat affected zones are investigated and documented. The resultant bonds are forcefully pulled apart to measure their bond strength. Optimal mean bond strength of 15.14 MPa is recorded for 355 nm wavelength at parameters combinations with highest laser power within the fluence window and low scanning velocity.