Low Cost Glass Interposer Development

Abstract

For high density interconnection IC packages of the future, the outlook is for thinner packages with higher routing densities. With that, managing the substrate warpage becomes critical. Traditional organic substrates may face several challenges for high density I/Os with very fine line interconnections. Glass is one of the candidates that can be used in substrate industry. The infrastructure of glass for LCD industry has already been developed for many years. Glass also has several superior properties than other substrate candidates, such as large panel size availability, adjustable CTE, high modulus, low dielectric constant, low dielectric loss and high insulating ability. In this paper, we successfully demonstrate early manufacturing feasibility of glass substrate with 4 build-up layers starting with a thin glass panel of thickness of 200μm in 508mm μ 508mm panel size format and under the IC substrate manufacturing environment. Fabrication and electrical results of a test vehicle are documented. The test vehicle includes daisy chains that are connected with 100μm diameter through glass via (TGV) in a 200μm thick glass. The laser via in via technology was adopted for double side electrical connection. The copper line width/space of 8/8μm was demonstrated. The total thickness of 4 layers test vehicle is about 390μm. The warpage of glass in comparison with an organic substrate (BT) with 200μm core thickness is 3X better. Further work is needed to develop, fine tune and assess the detailed manufacturability and reliability concerns. Based on this work, it is clear that the potential of glass in IC packaging and integration is tremendous in diverse applications for substrate warpage enhancement.