三维集成系统中硅通孔复合结构可靠性关键问题研究

The three-dimensional integration technology is one of those integration technologies which can keep the semiconductor industry developing rapidly. Through Silicon Via (TSV) is one of the key elements for three-dimensional integration. This composite structure contains four layers and three interfaces. Four layers are bulk silicon, insulating layer, barrier layer and metal core. Three interfaces are formed by adjacent two layers in the TSV. There are various factors such as multi-physical effects, micro-structure of each layer, interfacial characterization, stress, process, etc. closely related to the reliability of TSVs and three-dimensional systems. But until now, very few researchers carry out work on reliability of TSV systematically at home or abroad. In order to be clear on key factors and mechanism of TSV’s reliability, we will devote to build accurate theoretical model for reliability. It is needed to deeply research on the influence of the micro-structure and thermal properties of each layer, interfacial characterization and stress on reliability of TSVs with different structures, different materials or different process. This foundation will mainly focus on analysis of thermal reliability and accurate thermal model of TSVs. There are three research contents. The first one is the theoretical model of multi-physical field effects in TSVs. The second one is effects of micro-structure, thermal properties and process of each layer and interfacial characterization on reliability of TSVs. And the third one is mechanism of every kinds of stress in TSVs and effect of stress on reliability of TSVs. The research results of the foundation will theoretically guide high quality process and high reliability analysis of TSVs and three-dimensional integrated systems. And they will contribute to the progress of commercialization of three-dimensional integration technology.

三维集成被认为是最有可能延续半导体产业快速发展的集成技术之一。硅通孔是实现三维集成的关键因素，它是包含体硅-绝缘层-势垒层-金属芯的四层三界面复合结构。从其内部多物理场效应到材料生长工艺的诸多因素都会影响这一复杂结构的可靠性。目前，对硅通孔复合结构可靠性的系统研究在国内外都鲜有报道。本项目将从建立精确的可靠性理论模型出发，深入研究硅通孔内部各层材料的微观结构、热学性质、层间界面特性以及机械应力等关键因素对可靠性的影响。研究重点为硅通孔复合结构的热可靠性分析和精确的热学模型。研究内容包括其内部多物理场效应的理论分析，各层材料的微观结构、热学性质、制作工艺、层间界面特性以及机械应力等对可靠性的影响。目标是形成硅通孔复合结构的精确热学理论模型和系统的可靠性评价方法，为高质量硅通孔和高可靠性三维集成系统的制作和测试分析提供理论依据。项目成果有利于加快推动三维集成技术产业化。

本项目的研究内容包括TSV 内部的电、热、力等多物理场效应及可靠性模型，TSV原始孔制备工艺的可靠性评价，TSV性能和可靠性与介质层和势垒层的微观结构、热学性质、层间界面特性之间的关系，金属芯的微观结构、热学性质以及机械应力对TSV 复合结构可靠性的影响。研究目标是理清影响TSV 复合结构可靠性的关键因素和机理，为高质量TSV 和高可靠性三维集成系统的制作和测试分析提供理论依据。经过四年的深入研究，完成了项目计划书中列出的相关研究内容，并开展了相关的扩展研究。具体如下：.（1）TSV的电、热、力可靠性模型。研究了三维集成系统中TSV稳态热学模型、力学模型和电学模型，建立了TSV的分段热阻解析模型和斜四棱锥热路计算模型，仿真分析了TSV的热、力、电特性，以及电致热应力、热-力-电三场耦合特性。.（2）TSV的制备工艺以及各填充层的微观结构和界面结构对可靠性的影响。用BOSCH刻蚀工艺刻蚀原始硅通孔，经多次热氧化削减扇贝纹后通过高温热氧化生长绝缘层，然后用磁控溅射沉积势垒层和铜种子层，最后通过电镀填充铜金属芯。并基于COMSOL仿真分析了各填充层的微观结构和界面结构对可靠性的影响。.（3）扩展研究了单芯片三维集成技术，创造性地提出了单芯片三维双极型集成工艺，基于该项原创技术容易扩展出单芯片三维集成BiCMOS工艺以及单芯片三维集成BCD工艺。扩展研究了三维光电集成系统中TSV的电磁学模型，为后续全面、深入研究TSV打下了基础。.（4）扩展研究了多层芯片堆叠键合工艺及键合界面可靠性问题，创造性地提出了电镀直接键合技术，相较于铜-锡共晶键合、铜-铜热扩散键合具有明显优势。扩展研究了在功率芯片衬底中嵌入TSV阵列提升芯片散热能力的方法，理论分析和有限元仿真结果表明该方法效果明显，后续将对该项工作开展更深入的研究，研究成果将与贵州振华风光半导体有限公司联合开展产业化应用。.项目研究内容已完成、研究目标已基本达成。部分扩展研究的工作具有创造性，后续将开展全面、深入的研究。