Trans-wafer processing of semiconductors with nanosecond mid-ir laser radiation

Abstract

In recent years, a major push was made for the use of novel laser sources in the processing of semiconductors and other materials used in photovoltaic and IC applications. In addition to a large number of highly automated laser processes already adopted by the industry, more laser-based processing approaches are being developed to improve performance and reduce manufacturing costs. Common semiconductors are transparent in the infrared spectral region. Therefore laser sources operating at mid-IR wavelengths can be successfully utilized to induce material modifications in semiconductor wafers even beyond the laser-incident surface. We present our initial studies of this processing regime utilizing a self-developed nanosecond-pulsed thulium fiber laser emitting at the wavelength 2 μm. Our experimental approach confirmed that morphology changes could be induced not only at the front (laser-incident) surface of the wafer, but also independently at the back surface. We investigated the influence of process parameters, such as the incident pulse energy, duration and focusing conditions, on the induced surface morphology. In addition, we studied experimental routes to a number of potential applications of this processing regime, such as the PV cell edge isolation and the wafer scribing. Show more