Determination of the mobile ion fraction in molding composite materials : influence of time and temperature

Abstract

Nowadays, semiconductor devices are used in many aspects of our daily life and drive innovation within the industrial sector. Molding Compounds (MCs), used as an encapsulation material, play an important role in the lifetime of these devices. MC is a composite material consisting of silica particles, synthetic polymer, and additives. Ionic contamination within the material has a major impact on the reliability, as electrical fields may induce ion migration and accumulation on the microchips. As not every ionic species is mobile within MC, it is of great interest to determine the mobile ion fraction from the total and mobile ion content.For industrial application, the standard SEMI G29 is used as an extraction procedure which requires 48 h of extraction time using 100 mL of water and 10 g of MC at 120 °C with subsequent analysis of the derived extract using Inductively Coupled Plasma Mass Spectrometry/Optical Emission Spectroscopy (ICP-MS/OES). This brings two disadvantages: long preparation and great sample consumption, resulting in low sample throughput. As a result, manufacturers tend to shorten the extraction time leading to incomparable results. In this work, a method for total ion quantification within MC via ICP-MS was developed. A microwave-based extraction method using ICP-OES was developed for mobile ion determination which was then compared to the standard procedure. Extraction times and temperatures were varied from 30 min to 96 h and 60 °C to 225 °C. Results show that elements Li, Na, K, Mg and Ca are mobile within already 30 min of extraction and shorter extraction times and higher temperatures are favorable, yielding a higher sample throughput. With these results, further experiments can be conducted, investigating the short-term leaching behavior of MC.