Quantitative Evaluation of Strength Degradation at Interfaces in IC Packages and Formulation of a Fundamental Mechanical Device Reliability Strategy

在处理和服务过程中识别分层的包程序集中的接口。提出了一种设计和预测这些界面机械可靠性的基本方法，以取代目前利用加速测试协议的经验和相当耗时的方法。实施所提出的策略需要(1)开发一种基本的界面强度测量工具，能够在实际设备和封装结构中原位测试界面；(2)原位测量所选界面的抗拉强度，作为湿度、温度和时间变量的函数；(3)使用FTIR和热重分析对每个测试样品进行水分含量量化。这将产生“界面强度图”，用于预测在不同湿度和温度条件下所选界面的退化。然后，开发良好的模拟代码可以预测封装组件内任何接口的应力集中、湿气积累和温升，以确定(a)在任何IC制造和封装之前，接口是否能够在设计阶段本身的处理和系统集成周期中存活下来，以及(b)在制造时所需的接口强度水平，以确保规定的使用寿命。上述过程将首先通过研究下填体/氮化硅钝化层界面来演示。界面抗拉强度的原位测量将通过修改PI先前开发的激光散裂方法来完成。

Interfaces in package assemblies where delaminations during processing and service are identified. A fundamental approach for designing and predicting the mechanical reliability of these interfaces is proposed, with a view to replace the current empirical and rather time-consuming approaches that utilize accelerated test protocols. Implementation of the proposed strategy requires (1) the development of a fundamental interface-strength-measuring tool capable of testing interfaces, in-situ, in actual device and package structures, (2) measurement of the tensile strength, in-situ, of the selected interface as a function of humidity, temperature, and time variables, and (3) quantification of the moisture content using FTIR and thermogravimetric analyses on each tested sample. These will result in "interface strength charts" for predicting degradation at the selected interface for varying humidity and temperature conditions. Well developed simulation codes can then predict stress concentrations, moisture accumulation, and temperature rise at any of the interfaces within the package assembly for determining (a) whether the interface will be able to survive processing and system integration cycles during the design phase itself, prior to any IC fabrication and packaging, and (b) the level of interface strength needed at the time of manufacturing for ensuring a prescribed service life. The above procedure will first be demonstrated by studying the underfill/Si3N4 passivation layer interface. Measurement of the interface tensile strength, in-situ, will be accomplished by modifying a laser spallation method, developed previously by the PI.