Development and demonstration of a high-rate laser drilling process for EWT and MWT cell concepts
Drilling rates of up to 20,000 holes per second by beam splitting and parallelization
Experimental studies for identification of the relevance of laser-induced damage
Production and evaluation of MWT cells from laser-drilled wafers
Main Project Achievements Laser drilling was developed toward the goal of drilling 10,000 holes/s with a single process stage. This was achieved on the basis of a simulation which allows the identification of suitable laser sources. The drilling laser delivered by Trumpf was not suitable for this, due to much to large focus diameters. An alternative was found in the form of two coupled Jenlas IR70 which could be used for this at the application lab of Jenoptik. A drilling rate of 9,700 holes/s on 200 µm thick wafers and 12,500 holes/s on 180 µm thick wafers was achieved. That two coupled lasers were required (mainly to achieve a repetition rate of 60 kHz) shows that laser source development is required on this front.
A parallelization of the process to achieve the project goal of 20,000 holes/s could not be realized due to the lack of a proper demonstration platform for this process. Our process development shows that with 100 µm thin wafers a drilling rate of 20,000 holes per second could be achieved with a single processing stage. However, such thicknesses are currently not readily available and the market development indicates that the wafer thickness will not be reduced as predicted a few years ago.