Spray Pyrolysis Synthesized Self-biased Hexagonal Ferrite Thin Film on GaN, AlN, Si Substrates for Millimeter-wave Devices

用于毫米波器件的 GaN、AlN、Si 衬底上喷雾热解合成自偏置六方铁氧体薄膜

基本信息

批准号：
1808147
负责人：
Mohammed Afsar
金额：
$ 40万
依托单位：
Tufts University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-01 至 2021-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808147&HistoricalAwards=false
关键词：
Spray Pyrolysis Synthesized Self biased

项目摘要

With the advent of advanced wireless communications the spectrum at lower frequencies are congested. To overcome this congestion an alternative approach is to develop compact and high efficient communication system using passive devices operating in millimeter-wave frequency band. The materials used at these frequencies are Ba- and Sr hexaferrites. The anisotropy of these ferrites exhibit strong ferromagnetic resonance up to 60 GHz (5 mm in wavelength). The oxygen molecule in the atmosphere exhibit a strong resonance absorption of electromagnetic waves at 60 GHz. Thus makes it a very attractive frequency band for shorter distance communication system. In current proposal, the use of self-biased hexagonal ferrite devices is suggested in millimeter wave frequencies. This led to shift from silicon, narrowband gap substrate technology to GaN, wideband gap substrate technology for efficient performance of communication system. The Ba- and Sr- ferrite nano size powders are now readily available from a number of manufacturers. Recently it has been found that nano-sized hexagonal ferrite powders can be mixed with commercially available photoresist and then sprayed as a layer on to the GaN substrate. It is proposed to use one ultrasonic generator with two ultrasonic spray nozzles with compressed air shaper for spraying. The next step turns out to be curing of the film in an oven up to 600 degrees centigrade for narrowing of the ferromagnetic resonance peak. It also leads to doubling of the resonance intensity. The comprehensive characterization study of deposited nano-ferrite film has been performed by employing a custom made quasi-optical millimeter wave spectrometer, scanning electron microscope, X-ray diffraction analysis and vibrating sample magnetometer.For a communication system, one would need a high efficient power amplifier, a low noise amplifier and a nano-ferrite circulator. However, the process to manufacture high quality nano-ferrite material with good grain size offer significant challenges. One of the problem is how to deposit self-bias hexagonal ferrite thin film with both good quality and acceptable cost has not been solved yet. Currently available wafers for MMIC design are about 100 mm in diameter with a thickness of about 100m. Typical thicknesses are 98 m of SiC and 2 m of GaN. The development of high purity GaN thick film film on SiC turns out to be big challenge in the near future. A thin film of highly pure wide bandgap semiconductor such as Aluminum Nitride can also be deposited on SiC. It is a new technology and it will be explored during the course of the proposed research period. Originally this work was explored on IBM silicon CMOS substrates. The lower temperature operation restricted the deposition of nano ferrite Ba- ferrite film to porosity and uneven flatness. The work with silicon CMOS substrate will also be continued. The collaborative partnership with QORVO has led to the use of GaN on SiC wafers routinely. The ultimate goal is to have Ba-ferrite circulator, power amplifier and low noise amplifier build on a single GaN on SiC wafer for operation at 60 GHz.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.

随着先进无线通信的出现，较低频率的频谱变得拥挤。为了克服这种拥塞，另一种方法是使用在毫米波频段运行的无源器件来开发紧凑且高效的通信系统。在这些频率下使用的材料是 Ba 和 Sr 六方铁氧体。这些铁氧体的各向异性表现出高达 60 GHz（波长 5 毫米）的强铁磁共振。大气中的氧分子对 60 GHz 电磁波表现出强烈的共振吸收。因此，它对于短距离通信系统来说是一个非常有吸引力的频段。在当前的提案中，建议在毫米波频率中使用自偏置六角形铁氧体器件。这导致从硅窄带隙衬底技术转向 GaN 宽带隙衬底技术，以实现通信系统的高效性能。现在许多制造商都可以轻松获得Ba-和Sr-铁氧体纳米尺寸粉末。最近发现，纳米尺寸的六方铁氧体粉末可以与市售光刻胶混合，然后作为一层喷涂到GaN衬底上。建议采用一台超声波发生器、两个超声波喷嘴、压缩空气整形器进行喷涂。下一步是在高达 600 摄氏度的烤箱中固化薄膜，以缩小铁磁共振峰。它还导致共振强度加倍。采用定制的准光学毫米波光谱仪、扫描电子显微镜、X射线衍射分析和振动样品磁强计对沉积纳米铁氧体薄膜进行了全面的表征研究。对于通信系统，需要一种高效的功率放大器、低噪声放大器和纳米铁氧体环行器。然而，制造具有良好晶粒尺寸的高质量纳米铁氧体材料的工艺面临着巨大的挑战。问题之一是如何沉积质量良好且成本可接受的自偏压六方铁氧体薄膜尚未解决。目前用于MMIC设计的晶圆直径约为100mm，厚度约为100m。 SiC 的典型厚度为 98 m，GaN 的典型厚度为 2 m。在SiC上开发高纯度GaN厚膜在不久的将来将是一个巨大的挑战。高纯宽带隙半导体薄膜（例如氮化铝）也可以沉积在 SiC 上。这是一项新技术，将在拟议的研究期间进行探索。这项工作最初是在 IBM 硅 CMOS 基板上进行探索的。较低的操作温度限制了纳米铁氧体Ba-铁氧体薄膜的沉积，导致孔隙率和平整度不均匀。硅CMOS衬底的工作也将继续进行。与 QORVO 的合作伙伴关系导致了 SiC 晶圆上 GaN 的常规使用。最终目标是在单个 GaN on SiC 晶圆上构建 Ba 铁氧体环行器、功率放大器和低噪声放大器，以在 60 GHz 下运行。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识产权进行评估，被认为值得支持。优点和更广泛的影响审查标准。