SBIR Phase II: Crystalline Ferroelectrics Combined with Transistor Technology

这个小企业创新研究第二阶段项目将专注于开发利用铁电薄膜的电子特性的可调谐微波器件。具体来说，钛酸锶钡（BST）薄膜正被用于开发新型可调谐微波器件，包括移相器、延迟线和频率捷变滤波器。目前，这些铁电器件有两个缺点：易于形成的平面器件需要非常大的调谐电压，约为100伏，而易于调谐的平行板器件需要复杂的加工技术。这些问题阻碍了商业上可行组件的开发。目前的项目建议将硅基电路与铁电器件结合在同一衬底上。例如，硅电荷泵电路可以集成在芯片上，为铁电移相器提供高调谐电压。电压将被隔离到芯片上，并且需要小于3伏的电压来外部驱动设备。将硅半导体技术与铁电体相结合，将有助于开发利用铁电体介电特性的器件，并克服目前这些器件商业化道路上的障碍。在商业上，铁电薄膜在无线工业中的应用引起了极大的兴趣，因为这种材料能够极大地改善现有设备的功能。例如，一种铁电双工器是可能的，它的尺寸是现有双工器的三分之一，而功耗却低40%。今天的多频段手机使用多达四个滤波器，因此铁电体的潜力是巨大的。一家主要的无线手机制造商确定了至少六种可调谐设备在其手机内的应用。总体而言，无线通信市场催生了对小型、低功耗、高带宽微波元件的需求。2002年，无线手机的销售额超过500亿美元，其中60亿美元用于射频半导体组件。随着像PDA这样的高功能无线设备的发展趋势，对无线组件的需求将继续飙升。

This Small Business Innovative Research Phase II project will focus on developing tunable microwave devices that utilize ferroelectric thin films for their electronic properties. Specifically, barium strontium titanate (BST) thin films are being used to develop new classes of tunable microwave devices, including phase shifters, delay lines and frequency-agile filters. Currently, these ferroelectric devices suffer from two drawbacks: easily formed planar devices demand very large tuning voltages on the order of 100 Volts , while easily tuned parallel plate devices require sophisticated processing techniques. These problems have inhibited the development of commercially viable components. The current project proposes combining silicon based circuitry with ferroelectric devices on the same substrate. For example, a silicon charge pump circuit can be integrated on-chip to provide high tuning voltages for a ferroelectric phase shifter. The voltage will be isolated to the chip and less than 3 Volts would be needed to externally drive the device. Combining silicon semiconductor technology with ferroelectrics will enable development of devices which take advantage of ferroelectric's dielectric properties and overcome the current roadblocks in the way of commercializing these devices. Commercially, a great deal of interest has emerged in the use of ferroelectric thin films in the wireless industry because of the material's ability to dramatically improve the functionality of existing devices. For example, a ferroelectric duplexer is possible which has one third the size of existing duplexers, while using 40% less power. Today's multiband handsets use up to four filters, so the potential for ferroelectrics is tremendous. A key wireless handset manufacturer identified at least six applications for tunable devices inside their telephones. Overall, the wireless telecommunications market has spawned the need for small, low power, high bandwidth microwave components. Over $50 billion of wireless handsets were sold in 2002, with $6 billion being spent on RF semiconductor components. With the trend towards highly functional wireless appliances like PDA's, the demand for wireless components will continue skyrocketing.