STTR Phase I: Silicon-Integrated Epitaxial Barium Titanate (BaTiO3) Chips for Photonics Applications

这项小型企业技术转移（STTR）第一阶段项目的更广泛/商业影响是大规模生产用于光子集成电路的标准化，大面积硅基材料平台（晶圆）。光子学是信息处理的下一步，使用光信号代替电子。这种材料平台有望彻底改变硅光子学市场，就像引入硅芯片对微电子工业所做的那样。成功生产这种晶圆的第一步是控制由两种材料（光学材料钛酸钡（BaTiO3）和硅载流子芯片）结合产生的极端热应力，这两种材料的热膨胀率非常不同。将研究各种加工技术，以确定如何减轻这种热应力。如果成功，这种新材料平台将被电信和数据公司使用，并可能实现新型计算，如光子量子计算。到2030年，这些行业的总市场规模预计将超过1000亿美元。这个STTR一期项目将解决将钛酸钡硅技术扩展到更厚、更大面积晶圆的关键问题之一。钛酸钡和硅具有非常不同的热膨胀，由于集成是通过在高温下沉积实现的，冷却会产生很大的应力。由此产生的应力可能导致薄膜出现裂纹，甚至使晶圆片破碎。应力也会影响材料的光学性能，因此，其管理对后续器件制造至关重要。该公司正在开发一种工艺来缓解这一问题（例如，程序冷却），这将影响晶圆生产吞吐量。此外，公司必须控制铁电极化的方向，这是客户对制造器件的重要要求。解决这两个问题是该技术成功商业化的关键。钛酸钡薄膜的厚度从0.2微米到2微米将被集成在硅上，并受到不同的热历史。残余应力将用x射线衍射测量并用偏振拉曼光谱确证。由此产生的晶体结构、形貌、偏振分布和电光性能将被用作确定热加工是否成功的指标。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The broader / commercial impact of this Small Business Technology Transfer (STTR) Phase I project is mass production of a standardized, large-area, silicon-based materials platform (wafer) for photonic integrated circuits. Photonics is the next step in information processing, using light signals instead of electrons. Such a materials platform is expected to revolutionize the silicon photonics market much like the introduction of silicon chips did for the microelectronics industry. The first step to successfully produce such wafers is to manage the extreme thermal stress arising from the combination of two materials (the optical material barium titanate (BaTiO3) and the silicon carrier chips) with very different rates of thermal expansion. Various processing techniques will be investigated to determine how such thermal stress can be mitigated. If successful, this new materials platform will used by telecom and data companies, and may enable new kinds of computing, such as photonic quantum computing. The total of these industries is expected to exceed $100 billion in combined market size by 2030. This STTR Phase I project will address one of the critical issues of scaling up barium titanate on silicon technology to thicker and larger area wafers. Barium titanate and silicon have very different thermal expansions and since the integration is achieved by deposition at elevated temperature, cooling causes large stresses to develop. The resulting stress may result in cracks in the film or even in shattering the wafer. Stress also affects the optical performance of the material and therefore, its management is crucial for subsequent device fabrication. The company is developing a process that mitigates this problem (e.g., programmed cooling) which will affect wafer production throughput. In addition, the company must control the direction of ferroelectric polarization, an important customer requirement for making devices. Solving these two issues is crucial to successful commercialization of this technology. Barium titanate films of thicknesses ranging from 0.2 to 2 micrometers will be integrated on silicon and subject to different thermal histories. Residual stress will be measured by x-ray diffraction and corroborated with polarized Raman spectroscopy. The resulting crystal structure, morphology, polarization distribution, and electro-optic performance will be used as metrics for determining if the thermal processing was successful.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.