三維積體電路關鍵技術之金屬高分子混合接合研究

Abstract

本論文為研究金屬與高分子材料之混合接合在三維整合結構的特性分析，藉由此方案可同時提供絕佳的接合強度及傑出的電性。經過材料的選擇及測試，我們選擇金屬銅、錫作為內連線以及高分子材料-苯並環丁烯作(BCB)為介電材料，進一步地我們提出三維整合結構。此結構採用面對面接合、銅TSV以及銅/錫對BCB混合接合等先進關鍵技術。經過TSV製作、銅/錫與BCB顯影、混合接合、晶圓磨薄及背面金屬連線的一連串流程製作而成。在這三維整合結構，包含克爾文結構(Kelvin structure)及菊花鏈(daisy chain)設計。在5μm 及10μm 大小、深度在40μm深的TSV測試結構，分別量測到49.3mΩ及12.6mΩ的阻值。傑出的電性也指出此設計的結構符合預期並可應用在未來3DIC相關產品上。最後，我們也測試一些可靠性的實驗，包括溼度、長時間電流，也證明了BCB材料可提供良好接合品質。

The main topics of this thesis include electrical characterization and reliability investigation of metal to polymer hybrid bonding in three-dimensional integrated circuit. Hybrid bonding is one of the most important technologies in 3D-ICs because of dielectric polymer and metal can provide reinforcement of bonding strength and electrical interconnection simultaneously. Cu/Sn micro-bumps and BCB (benezocy-clobutene) were adopted and optimized to form metallization and dielectric material for hybrid bonding. As the result, a wafer-level three-dimensional integration scheme with Cu TSVs, based on face-to- face and Cu/Sn micro-bumps to BCB low temperature hybrid bonding, was demonstrated. The main process flow includes the sequence of Cu TSV formation, Cu/Sn and BCB development, hybrid bonding, wafer thinning and backside re-distribution metal layer. Kelvin structure and daisy chain design were fabricated for electrical characterization and stability evaluation. Reliability tests such as current stressing and humidity test were performed without deterioration, showing good sealing ability of BCB. The results of Kelvin structure for 10μm TSV are 49.3 mΩ for 5μm TSV and 12.6 mΩ, indicating excellent electrical characterization to allow the possibility of future mass production for 3D IC area.