标题: | 高功率氮化铝镓/氮化镓高电子迁移率电晶体之金属接触制程研究 The Study of Contact Metals for High Power AlGaN/GaN High Electron Mobility Transistors Application |
作者: | 张智翔 Chung, Chih-Hsiang 施敏 张翼 Sze, Min Chang, Yi 电子工程学系 电子研究所 |
关键字: | 氮化镓;高功率;高电子迁移率电晶体;欧姆接触;萧基接触;GaN;high power;HEMT;Ohmic contact;Schottky contact |
公开日期: | 2013 |
摘要: | 氮化镓具有高电子迁移率、高载子浓度和高崩溃电压等优点,使它适合用在高功率和高频元件上。但是制作氮化镓元件的成本太高使它无法与传统矽元件竞争,主要的原因为采用金的金属化制程,因为金价格太贵而占据了大部份制造成本。如果我们可以用其他金属取代金,氮化镓元件在市场上将更具竞争力。所以我们可以藉由发明新的接触来达到这个目标。 钨是一种高熔点和高密度的金属,它不需要扩散阻挡层因为它的化学安定性非常好。在我的研究中使用钛/铝/钨做为欧姆接触来制造无金元件,并藉由原子力显微镜和电性量测来和传统元件作比较。结果显示他它们具有绝佳的表面起伏和高压可靠度。 另外我采用钨、氮化钨、氮化钛、氮化钨/铜和氮化钛/铜做为萧基接触来取代传统镍/金萧基接触。结果显示出和镍金相比他们具有较低的漏电流和较高的萧基障碍。最重要的是经过长时间高压和高温测试后它们特性几乎不受影响。这些研究成果将有助于解决高功率元件中自体发热和漏电流等问题。 GaN has high electron mobility, high carrier concentration and high breakdown field. These advantages make GaN suitable for high power and high frequency applications. However, the cost of GaN device processing is too high to compete with traditional Si-based devices. The main reason is the gold metallization. The price of gold is so high that it constitutes to a major portion of the fabrication cost. If we can replace gold with other kinds of metal, GaN devices will become more competitive in the commercial market. So a lot of new contact metals are being investigated to achieve this goal. Tungsten is a metal which has the highest melting point and high density. Its chemical stability is great so that diffusion barrier layer is not needed. In this study, Ti/Al/W is used as a new Ohmic contact for gold-free devices. Atomic force microscopy and DC measurement are used to compare traditional devices and gold-free devices. The results show that they have excellent surface morphology and stress reliability. For Schottky contact, W, WN, TiN, WN/Cu and TiN/Cu are adopted to replace Ni/Au Schottky contact. The results show they all have lower gate leakage currents and higher Schottky barrier heights than Ni/Au. Most importantly, they stay nearly unchanged after long-term stress period and high temperature test. These results are helpful to solve self-heating and leakage current occurred in GaN high power devices. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT070050145 http://hdl.handle.net/11536/73367 |
显示于类别: | Thesis |