Selective dielectrical layer (SiNx) removal on the emitter side of the wafers is being done with femtosecond pulses. SiNx layer that is 50-90 nm thickness and covers emitter, must be precisely removed without harming emitter layer. One of applications is while ablation of dielectric, openings for bus bars (A) and fingers (B) are being created.
On the next step ablated openings of the wafers are covered by nickel. Later on the nickel layer copper is being deposited. In this way high quality front contacts are formed. Selective removal of dielectric layer is being done with femtosecond. Galvanometer scanners are used to control laser beam to cut emitter. Machine vision feature enables to detect wafer position and ablate the openings precisely. Flexible and reliable software named “SCA” helps to control the process with scientific and industrial modes.
