【作者】 胡永达；

【导师】 杨邦朝；

【作者基本信息】 电子科技大学 ， 微电子学与固体电子学， 2002， 博士

【摘要】 大规模集成电路的发展，对芯片之间的互连提出了更高的要求，高端电子系统中高密度封装技术逐渐成为发展的主流。多芯片组件（MCM）是微电子封装的高级形式，它是把裸芯片与微型元件组装在同一个高密度布线基板上，组成能够完成一定的功能的模块甚至子系统。MCM还能够实现电子系统的小型化、高密度化，是实现系统集成的重要途径，在MCM中高密度布线的多层基板技术是实现高密度封装的关键。 氮化铝（AlN）陶瓷具有高导热率、低介电常数、高强度、高硬度、无毒性、热膨胀系数与Si相近等良好的物理性能，采用氮化铝作为介质隔离材料制备的AlN多层布线共烧基板，在高密度、大功率MCM的封装以及MEMS封装等方面具有广泛的应用前景。 共烧导带浆料与AlN生坯之间的烧结应力是造成基板失效的原因。为了消除二者之间的烧结应力，共烧导带浆料与AlN生坯必须同时进入烧结状态，具有相同的收缩特性。通过采用单质SiO₂玻璃粉，代替Y₂O₃、CaO和SiO₂等的混合物添加剂，得到了在烧结初期优良的AlN共烧基板材料收缩一致性。 AlN陶瓷的助烧剂是CaO和Y₂O₃，在烧结过程中会形成YAlO和CaAlO液相。通过改变导带浆料中SiO₂的含量，在促使导带浆料完成烧结的同时，在导带中也保留一定数量的孔隙。这样在烧结过程的保温阶段，为AlN烧结过程中的YAlO和CaAlO液相扩散达到基板表面提供了一定的扩散通道和驻留空间，导带在保温阶段也能够随着AlN一起自由收缩。从而保证了AlN陶瓷介质材料和导带浆料，在保温阶段的收缩一致性。 在陶瓷介质和导带浆料之间的界面位置，有SiO₂、AlN，以及AlN的添加剂CaO和Y₂O₃存在，它们四种单质材料发生反应，在界面位置形成ysialon，casialon玻璃相和CaSiAlO和YSiO的晶相，提高了焊盘的附着力。 经过实验，发现SiO₂含量在0.45％质量分数时，浆料与基板之间能够满足匹配性要求，烧结应力小，AlN共烧基板能够达到足够的致密度和平整度。这时的导带方阻达到10mΩ／口，基板的翘曲度小于50μm／50mm，导带焊盘的键合强度大于3kgf／mm²，共烧基板的层数达到9层，AlN共烧基板尺寸达到50×50mm²。这些指标达到了国外九十年代初期的研究水平，完全满足实用化的要求。 电子科技大学博士学位论文 聚酚亚胺（PI）是薄膜多层布线的重要介质材料，它是由两种单体在热处理后聚合而成。它与金属薄膜的相互作用会影响金属薄膜材料的导电率，并且导致自身的性能变坏。n与CU反应后，形成络合物，热处理时自身降解，击穿强度降低，介电常数提高；CZ在热处理后从络合物离解出来形成CllO和CUZO。这些缺陷可以通过在PI和Cu之间采用Cr膜作为阻挡层来解决。 Cr／Cu／Cr是目前常用薄膜互连结构。通过分析AW衬底上沉积的Cr／Cu／Cr簿膜在不同热处理温度下的特性。得到以下结论：在 3 00 oC处理温度下，Cr、Cu之间的相互扩散小，Cr膜致密，Cu膜没有显著的氧化，能够满足薄膜导带的要求；但是升高温度至500oC以上，Cr、Cu膜之间的扩散加剧，Cr膜表面出现裂纹，Cu膜被氧化。Cr、Cu之间没有形成合金或化合物。更多还原

【Abstract】 With the development of VLSI, there are increasing demands for 1C interconnection. The high-density package technology becomes mainstream in advanced systems. Multichip module (MCM) is high-level mode in electronic package. MCM is that bare dice and microelements are assembled on a high-density interconnection (HDI) substrate. MCM can meet the demands of compact packaging and high density. It’s a method to realize system integration. The HDI substrate is critical to MCM.Aluminum nitride (A1N) has been considered as a material for ceramic packaging in view of the recent trends in the semiconductor industry toward higher speed, power dissipation and packaging density. This is because of its natural properties. These properties include a high thermal conductivity (200W/m K), a high mechanical strength and a thermal expansion coefficient close to that of silicon. Other electrical characteristics of A1N, such as insulation resistance, dielectric constant and dielectric loss are very close to those of Al2O3. These characteristics are suitable for semiconductor packaging that is required to have particularly high reliability. Thus, A1N substrate is useful for multi-chip module and for MEMS as packaging material.Low sheet resistance and good matching between substrate and paste are the principal requirements for conductor paste in multi-layer cofire substrate. We need to start their sintering at same temperature and to ensure conductor paste and green-sheet ceramic bodies have the same shrinkage rate.In this sense, SiO2 is a good additive. SiO2 is used as a component in many kinds of pastes. The softening point of pure SiO2 glass is at about 1600, the same temperature at which A1N green-sheet ceramic bodies start shrinkage. SiO2 can react with A1N and form sialon glass. In this paper, a tungsten paste is proposed with SiO2 glass as the only additive.CaO and Y2O3 are additives in A1N green sheet. YA1O and CaAlO complex oxides have low melting point compare to the soaking temperature of A1N sintering. YA10 and CaAlO complex oxides become liquid phase in the process of sintering. SiO2reacts with CaO, A12O3 and Y2O3, producing CaSiAlO and YSiO phases which are detected at the interface between conductor paste and A1N substrate. Ysialon and casialon glasses also form at the interface.If 0.45%wt SiO2 is added in the paste, the tungsten paste has low sheet resistance and matching shrinkage of A1N green-sheet bodies. At this concentration of SiO2 in the paste, A1N substrate is little porous at interface. A1N grains at interface are no different from those in the bulk. The sintering stress is decreased to the degree that cannot influence the substrate shrinkage. The A1N substrate contains nine levels with size of 50 50mm2. The sheet resistance is 10m/, substrate bending is smaller than 50 u m/50mm and adhesion strength is greater than 30MPa.Polyimide (PI) is a thermally stable insulator and is used in multi layer thin-film interconnection (MCM-D). PI is made from precursors after heat treat. These precursors polymerize to form polyamic acid (PAA). The PAA reacts with metal film such as copper. Thus its character become worse and circuit resistance increases. Having reacted with copper, PAA becomes complex. The complex decomposes after heat treating and cause the increase in dielectric constant and reduction in dielectric breakdown strength. Otherwise Cu2O and CuO emerge from the complex, too. These defects can be overcome by a film structure of Pl/Cr/Cu/Cr.Cr/Cu/Cr film has been widely used in MCM-D. Having been treated at variable temperature in atmosphere, we can get the conclusions: (1) Treated at 300, there are little diffusion coefficients between Cu and Cr; (2) Treated over 500, Cr and Cu diffuse into each other evidently. Cu film oxidizes and there are cracks in Cr film. Cr and Cu cannot form alloy and compound at any temperature.更多还原