硅基无金增强型氮化镓高电子迁移率晶体管的工艺研究

RESEARCH ON SILICON-BASED GOLD-FREE ENHANCEMENT GALLIUM NITRIDE HIGH ELECTRON MOBILITY TRANSISTOR

林新鹏

11649125

硕士

微电子学与固体电子学

于洪宇

2018-06-02

2018-07-09

哈尔滨工业大学

深圳

氮化镓材料以其宽禁带、高击穿、高电子迁移率和高电子气密度逐渐步入功率器件的舞台。这些优良的材料特性，使得氮化镓功率器件较硅功率器件有更好的能源利用效率，随着世界上的能源资源日趋减少和减少温室气体排放，更加高效的电力转换装置逐渐成为热点研究方向。配备氮化镓功率器件的系统装置不仅可以提高电力转换的效率还能满足个人移动终端所需求的便携要求，并且可以小型化家庭电器从而获得更加宽阔的空间。本文在此背景下进行研究，制作氮化镓功率器件。为了制作出氮化镓器件首先进行了器件源漏两极的欧姆接触研究，分别研究了有金和无金欧姆接触。无金膜层Ti/Al/W（20/100/30 nm）膜层在800°C 退火条件下实现了最低0.65Ω∙mm 的接触值。研究了等离子刻蚀，对比了ICP 和RF 功率、刻蚀气体Cl2的比例和不同腔体压力对刻蚀表面粗糙度的影响，并给出了接触电阻与刻蚀时间的关系，为无金欧姆接触的势垒层刻蚀做出了参考。接着介绍了两种栅极介电材料的淀积方法，由于使用后栅工艺高温LPCVD 生长的SiNX 将破坏欧姆接触，因此实验采用ALD 在300°C 淀积Al2O3 作为栅极介电层材料，选用Ni/TiN 作为栅极金属。通过凹栅工艺实现了阈值电压为1.2 V 的增强型器件，但是凹栅工艺对沟道电子气的损伤过大，导致饱和漏极电流值降为5.2 mA 左右。最后研究了与合作商共同开发的器件的可靠性，包括低温栅极脉冲应力和经时击穿测量。低温栅极脉冲测试揭示了栅极应力下的阈值电压变化的异常行为，表现为先减小后增大，提出了相应的模型并得到验证。通过经时击穿测试讨论了栅介质面积和多指对SiNX 特性的影响。

Gallium nitride materials gradually step into the power device stage with its wide band gap, high breakdown, high electron mobility, and high electron gas density. These excellent material properties make GaN power devices have better energy efficiency than silicon power devices. As the world’s energy resources are increasingly reduced and greenhouse gas emissions are reduced, more efficient power conversion devices are gradually becoming a hot research direction. A system device equipped with a gallium nitride power device can not only improve the efficiency of power conversion but also meet the portable requirements demanded by personal mobile terminals and also can miniaturize home appliances to obtain a wider space.In this context, this paper investigates and fabricates GaN power devices. In order to fabricate a GaN device, first, the ohmic contact of the source and drain electrodes of the device was studied. Gold and gold-free ohmic contacts were investigated. The gold-free Ti/Al/W (20/100/30 nm) layer achieves a minimum contact value of 0.65 Ω/mm at 800°C. Plasma etching was studied to compare the influence of ICP and RF power, the proportion of etching gas Cl2, and the pressure of different chambers on the etching surface roughness, and the relationship between the contact resistance and the etching time was given which make a reference to the ohmic contact barrier layer recess. Next, two deposition methods for the gate dielectric material are described. Since the SiNX grown by the high-temperature LPCVD after the gate process will damage the ohmic contact, an Al2O3 deposition at 300 °C. is used as the gate dielectric layer material for the device with Ni/TiN as a gate metal. An enhanced device with a threshold voltage of 1.2 V was realized by the recessed gate process, but the recessed gate process caused excessive damage to the channel electron gas, resulting in the saturation drain current value dropping to about 5.2 mA. Finally, the reliability of devices jointly developed with partners was studied, including low-temperature gate pulse stress and time-dependent dielectic breakdown measurements. The low-temperature gate pulse test reveals the abnormal behavior of the threshold voltage change under the gate stress, which shows that it decreases first and then increases. A corresponding model is proposed and verified. The effect of gate dielectric area and multi-finger on SiNX characteristics was discussed by the time dependent dielectric breakdown test.

氮化镓 功率器件 欧姆接触 增强型器件 经时击穿

GaN, power devices ohmic contacts enhanced devices time dependent dielectric breakdown

中文

联合培养

南方科技大学

林新鹏. 硅基无金增强型氮化镓高电子迁移率晶体管的工艺研究[D]. 深圳. 哈尔滨工业大学,2018.