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

该小型企业技术转让 (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，使用光信号而不是电子。这样的材料平台预计将彻底改变硅光子市场，就像硅芯片的引入给微电子行业带来的影响一样。成功生产此类晶圆的第一步是管理热膨胀率差异很大的两种材料（光学材料钛酸钡 (BaTiO3) 和硅载体芯片）组合所产生的极端热应力。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，例如光子量子计算。 预计到 2030 年，这些行业的市场总规模将超过 1000 亿美元。 STTR 第一阶段项目将解决将硅技术上的钛酸钡扩大到更厚和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，并且由于集成是通过在高温下沉积实现的，因此冷却会导致产生大的应力。由此产生的应力可能会导致薄膜破裂，甚至导致晶圆破碎。应力也会影响材料的光学性能，因此，其管理对于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个问题（例如程序冷却），该问题将影响晶圆生产量。此外，公司必须控制铁电极化的方向，这是制造器件的重要客户要求。解决这两个问题对于这项技术的成功商业化至关重要。厚度为 0.2 至 2 微米的钛酸钡薄膜将集成在硅上并经历不同的热历史。残余应力将通过 X 射线衍射测量并用偏振拉曼光谱证实。由此产生的晶体结构、形态、偏振分布和电光性能将用作确定热处理是否成功的指标。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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.