Quantitative Model-Based Photoelastic Characterization of Wafer-Bonding Stresses: a Tool for Industry and Education

智力优势：在这个项目中，将开发一个建模框架，以补充直接键合硅片中界面表征的新开发技术。红外灰场偏振镜（IR-GFP）光弹性测量技术是一种强大的方法，可以提供比其他技术更快的吞吐量和更精细的空间分辨率来研究直接键合界面的应力源。该方法可以对各种缺陷引起的应力强度进行定性比较，但它只能测量晶圆片中应力的全厚度平均值。新的建模方法将使表征技术更加定量，通过原子性地考虑表面粘附力，结合直接晶圆键合的粘附机制。将开发表面接触元素来模拟两个表面之间的原子相互作用，然后将对几个重要的几何形状进行计算和实验研究以进行验证。更广泛的影响：基于定量模型的表征方法将允许以高精度、分辨率和速度进行全场应力张量测量。这将对绝缘体上硅（SOI）器件加工的晶圆键合界面的工业检测做出重大贡献。该方法还将被开发为UIUC本科材料测试教学实验室的实验模块。通过将这种基于模型的实验技术作为材料实验室教授的表征方法，新一代的本科生将接触到与半导体行业相关的高科技方法，他们将研究小尺度系统中的接触力学，并且他们将学习光弹性的基础知识。

Intellectual Merit: In this project a modeling framework will be developed to complement a newly developed technique for interface characterization in direct-bonded silicon wafers. The infrared grey field polariscope (IR-GFP) photoelastic measurement technique is a powerful method that offers faster throughput and finer spatial resolution than other techniques for investigating stress sources at direct-bond interfaces. The method can make qualitative comparisons of stress intensities due to various types of defects, but it measures only a through-thickness average of stress in the wafers. The new modeling method will make the characterization technique more quantitative by incorporating the mechanics of adhesion in direct wafer bonding through an atomistic consideration of surface adhesion forces. Surface contact elements will be developed to mimic the atomistic interactions between the two surfaces, and several important geometries will then be studied both computationally and experimentally for validation. Broader Impact: The quantitative model-based characterization approach will allow for full-field stress tensor measurements with high accuracy, resolution, and speed. This will make a major contribution to the industrial inspection of wafer-bonded interfaces for silicon-on-insulator (SOI) device processing. The method will also be developed for use as a lab module in the Undergraduate Materials Testing Instructional Laboratory at UIUC. By including this model-based experimental technique as a characterization methods taught in the materials lab, a new generation of undergraduate students will be exposed to a high-tech approach relevant to the semiconductor industry, they will investigate contact mechanics in small scale systems, and they will learn about fundamentals of photoelasticity.