基于纳米多孔铜结构的低温热压键合技术研究

发布时间：2018-01-11 01:03

  本文关键词：基于纳米多孔铜结构的低温热压键合技术研究　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 三维封装 Cu-Cu低温键合 脱合金 纳米多孔铜结构 热压键合

【摘要】：三维封装是一种先进的封装互连技术,具有互连距离短、信号传输快、集成度高、信号干扰少等优点。键合是使得芯片堆叠得以完成的关键技术,其中,铜-铜热压键合能同时完成电热连接和机械连接,因而成为三维封装的首选键合技术。然而,以往的铜-铜热压键合温度偏高,工艺时间长,效率普遍较低。因而亟需控制键合温度以增强产品性能并减小生产成本。纳米多孔铜结构具有比表面积大、表面活性高、扩散系数大以及纳米尺寸效应等特点,利用该特殊结构作键合层有潜力降低键合温度。当前,纳米多孔铜的主要制备手段是脱合金法,此方法工艺简单,且可通过调节工艺参数得到不同尺寸的纳米多孔结构。本文采用脱合金法制备纳米多孔铜,并使用此特殊结构作键合层以达到低温键合目的。主要研究内容包括:首先,讨论了基于纳米多孔铜的低温热压键合技术的原理。纳米多孔铜具有大比表面积、高表面活性、纳米尺寸效应,且较体材料软等特点,这些特性都有助于降低键合温度和压力;其次,以Cu-Zn合金为研究载体,分析了影响纳米多孔铜结构的关键因素,包括退火温度、镀锌时间以及腐蚀时间。研究表明,较低的退火温度难以使Cu、Zn完全合金化,而过高的退火温度又会产生热应力,合适的退火温度为150~160℃;随着镀锌时间增加,纳米多孔铜结构的孔径尺寸逐渐缩小并趋于稳定,分析得出较理想的镀锌时间为12min;而随着腐蚀时间增加,韧带出现粗化现象,适宜的腐蚀时间为10min;再次,对纳米多孔铜的热学性能和力学性能进行了分析。结果表明,纳米多孔铜在200℃便开始出现表面熔融现象,表明其熔化阈值温度远低于体材料;而纳米压痕测试结果表明,纳米多孔铜的硬度和杨氏模量均小于体材料;最后,分析了不同工艺条件对纳米热压键合质量的影响。在250℃低温下,键合压力为0.5MPa并持续120min,得到了良好的键合结果(拉伸强度高达5.2MPa)。而无纳米多孔铜的光面铜热压键合强度几乎为零,两者对比证实了基于纳米多孔铜低温键合的可行性。
[Abstract]:Three-dimensional packaging is an advanced packaging interconnection technology with the advantages of short interconnect distance, fast signal transmission, high integration and less signal interference. Bonding is the key technology to make chip stacking complete. Copper-copper hot pressing bonding can complete both electrothermal bonding and mechanical bonding, so it has become the preferred bonding technology for 3D packaging. However, the previous copper-copper hot pressing bonding temperature is high and the processing time is long. The efficiency is generally low, so it is urgent to control the bonding temperature to enhance the product performance and reduce the production cost. The nano-porous copper structure has the characteristics of large specific surface area, high surface activity, large diffusion coefficient and nano-size effect. Using the special structure as the bonding layer has the potential to reduce the bonding temperature. At present, the main preparation method of nano-porous copper is dealloying, and the process is simple. Different sizes of porous nano-copper can be obtained by adjusting the process parameters. In this paper, nano-porous copper was prepared by dealloying method. This special structure is used as the bonding layer to achieve the purpose of low temperature bonding. The main research contents include: firstly, the principle of low temperature hot pressing bonding technology based on nano-porous copper is discussed. The nano-porous copper has large specific surface area. The characteristics of high surface activity, nanometer size effect, and softer than bulk materials are helpful to reduce bonding temperature and pressure. Secondly, the key factors affecting the structure of nano-porous copper, including annealing temperature, galvanizing time and corrosion time, were analyzed with Cu-Zn alloy as the carrier. It is difficult to make Cu Zn alloying completely at lower annealing temperature, but too high annealing temperature will result in thermal stress. The appropriate annealing temperature is 150 ~ 160 鈩，

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