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摘要
U型槽的干法刻蚀工艺是GaN垂直沟槽型金属-氧化物-半导体场效应晶体管(MOSFET)器件关键的工艺步骤, 干法刻蚀后GaN的侧壁状况直接影响GaN MOS结构中的界面态特性和器件的沟道电子输运. 本文通过改变感应耦合等离子体干法刻蚀工艺中的射频功率和刻蚀掩模, 研究了GaN垂直沟槽型MOSFET电学特性的工艺依赖性. 研究结果表明, 适当降低射频功率, 在保证侧壁陡直的前提下可以改善沟道电子迁移率, 从35.7 cm2/(V·s)提高到48.1 cm2/(V·s), 并提高器件的工作电流. 沟道处的界面态密度可以通过亚阈值摆幅提取, 射频功率在50 W时界面态密度降低到1.90 × 1012 cm–2·eV–1, 比135 W条件下降低了一半. 采用SiO2硬刻蚀掩模代替光刻胶掩模可以提高沟槽底部的刻蚀均匀性. 较薄的SiO2掩模具有更小的侧壁面积, 高能离子的反射作用更弱, 过刻蚀现象明显改善, 制备出的GaN垂直沟槽型MOSFET沟道场效应迁移率更高, 界面态密度更低.-
关键词:
- GaN垂直沟槽型金属-氧化物-半导体场效应晶体管 /
- U型槽 /
- 射频功率 /
- 刻蚀掩模
Abstract
As reported by several market analysts, GaN-based power devices show great potential applications in the low and medium voltage range ( < 900 V). For high voltage ( > 1200 V), including ship transportation and power grid, the future applications of GaN highly depend on the development of vertical devices based on GaN substrates. Several vertical devices have been reported, such as current aperture vertical electron transistors (CAVETs), U-shape trench metal-oxide-semiconductor field-effect transistors (UMOSFETs), and fin power transistors. And the UMOSFETs show potential advantages due to greater simplicity in material epitaxy and fabrication process. In the fabrication of UMOSFETs, the U-shape trench dry etching is the most critical process. The GaN sidewalls after dry etching directly affect the interface state characteristics in the MOS structure and the channel electron transport. In this work, etching optimization including etching radio-frequency (RF) power and etching mask is investigated and process-dependent electrical characteristics of GaN UMOSFETs are also studied. The appropriate decrease of RF power ensuring the steep sidewalls can effectively improve the channel electron mobility from 35.7 cm2/(V·s) to 48.1 cm2/(V·s) and consequently increase the ON-state current and reduce the ON-state resistance. Larger etching damage to the p-GaN sidewall caused by higher RF power leads the scattering effects to increase and the mobility of the channel carriers to decrease. The interface state density at the channel can be extracted by the subthreshold swing. The interface state density decreases to 1.90 × 1012 cm–2·eV–1 when the RF power is regulated to 50 W, which is only half of the interface state density when RF power is 135 W. Similar breakdown voltages (350-380 V) are measured for these devices with varying RF power, which are governed by gate early breakdown. Positive valence band offset is formed in the SiO2/GaN MOS structure and the early breakdown occurs due to the holes accumulating at the SiO2/GaN interface. The etching uniformity at the bottom of U-shape trench can be improved by using the SiO2 hard masks instead of photoresist masks. Sub-trenches at both ends of the trench bottom are observed in the device with photoresist masks, leading the carrier scattering to increase and ON-state current to decrease. Besides, the interface state density decreases from 3.42 × 1012 cm–2·eV–1 to 2.46 × 1012 cm–2·eV–1 with a SiO2 hard mask layer used. Compared with 1.6 μm photoresist mask, the thinner SiO2 mask with a thickness of 500 nm has a small sidewall area, which weakens the high-energy ion reflection in the inductively coupled plasma system. Consequently, the over-etching at the bottom ends of the trench is improved significantly and therefore the fabricated GaN UMOSFET has higher channel mobility and a lower interface state density.-
Keywords:
- GaN vertical trench metal-oxide-semiconductor field-effect transistor /
- U-shape trench /
- radio-frequency power /
- etching mask
作者及机构信息
Authors and contacts
文章全文 : translate this paragraph
参考文献
[1] Uemoto Y, Hikita M, Ueno H, Matsuo H, Ishida H, Yanagihara M, Ueda T, Tanaka T, Ueda D 2007 IEEE Trans. Electron Dev. 54 3393 Google Scholar
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[3] Sun S, Fu K, Yu G, Zhang Z, Song L, Deng X, Qi Z, Li S, Sun Q, Cai Y, Dai J, Chen C, Zhang B 2016 Appl. Phys. Lett. 108 013507 Google Scholar
[4] Wang H, Wang J, Liu J, Li M, He Y, Wang M, Yu M, Wu W, Zhou Y, Dai G 2017 Appl. Phys. Express 10 106502 Google Scholar
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[6] Ambacher O, Smart J, Shealy J R, Weimann N G, Chu K, Murphy M, Schaff W J, Eastman L F, Dimitrov R, Wittmer L, Stutzmann M, Rieger W, Hilsenbeck J 1999 J. Appl. Phys. 85 3222 Google Scholar
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Cui X T, Chen W J, Shi Y J, Xin Y J, Li M L, Wang F Z, Zhou Q, Li Z J, Zhang B 2019 Semiconductor Technology 44 286 Google Scholar
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Tang W X, Hao R H, Chen F, Yu G H, Zhang B S 2018 Acta Phys. Sin. 67 198501 Google Scholar
[10] Lin R M, Chu F C, Das A, Liao S Y, Chou S T, Chang L B 2013 Thin Solid Films 544 526 Google Scholar
[11] Russo S, Di Carlo A 2007 IEEE Trans. Electron Dev. 54 1071 Google Scholar
[12] Horio K, Takayanagi H, Nakano H 2006 Phys. Status Solidi 3 2346 Google Scholar
[13] Meneghesso G, Rampazzo F, Kordos P, Verzellesi G, Zanoni E 2007 IEEE Trans. Electron Dev. 53 2932 Google Scholar
[14] Oka T, Ina T, Ueno Y, Nishii J 2015 Appl. Phys. Express 8 054101 Google Scholar
[15] Chowdhury S, Swenson B L, Wong M H, Mishra U K 2013 Semicond. Sci. Technol. 28 074014 Google Scholar
[16] Nie H, Diduck Q, Alvarez B, Edwards A P, Kayes B M, Zhang M, Ye G, Prunty T, Bour D, Kizilyalli I C 2014 IEEE Electron Dev. Lett. 35 939 Google Scholar
[17] Ji D, Chowdhury S 2015 IEEE Trans. Electron Dev. 62 2571 Google Scholar
[18] Otake H, Chikamatsu K, Yamaguchi A, Fujishima T, Ohta H 2008 Appl. Phys. Express 1 011105 Google Scholar
[19] Oka T, Ueno Y, Ina T, Hasegawa K 2014 Appl. Phys. Express 7 021002 Google Scholar
[20] Sun M, Zhang Y, Gao X, Palacios T 2017 IEEE Electron Dev. Lett. 38 509 Google Scholar
[21] Zhang Y, Sun M, Perozek J, Liu Z, Zubair A, Piedra D, Chowdhury N, Gao X, Shepard K, Palacios T 2018 IEEE Electron Dev. Lett. 40 75 Google Scholar
[22] Gupta C, Chan S H, Lund C, Agarwal A, Koksaldi O S, Liu J, Enatsu Y, Keller S, Mishra U K 2016 Appl. Phys. Express 9 121001 Google Scholar
[23] Fujishima T, Otake H, Ohta H 2008 Appl. Phys. Lett. 92 243505 Google Scholar
[24] Wang Q, Jiang Y, Zhang J, Kawaharada K, Li L, Wang D, Ao J P 2015 Semicond. Sci. Technol. 30 065004 Google Scholar
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Schroder D K (translated by Liu A M) 1998 Semiconductor Material and Device Characterization (Dalian: Dalian University of Technology Press) pp284−286 (in Chinese)
[26] Gupta C, Chan S, Pasayat S, Keller S, Mishra U 2019 J. Appl. Phys. 125 124101 Google Scholar
[27] Narita T, Kikuta D, Takahashi N, Kataoka K, Kimoto Y, Uesugi T, Kachi T, Sugimoto M 2011 Phys. Status Solidi A 208 1541 Google Scholar
[28] Kodama M, Sugimoto M, Hayashi E, Soejima N, Ishiguro O, Kanechika M, Itoh K, Ueda H, Uesugi T, Kachi T 2008 Appl. Phys. Express 1 021104 Google Scholar
[29] Flemish J R, Xie K 1994 Appl. Phys. Lett. 64 2315 Google Scholar
施引文献
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图 1 GaN垂直型UMOSFET器件示意图
Fig. 1. Cross-sectional schematic of a vertical GaN UMOSFET.
图 2 干法刻蚀RF功率为50, 75和135 W制备出GaN UMOSFET器件的电学特性曲线(IGS和IDS分别指栅电流和漏电流) (a)转移特性曲线; (b)沟道场效应迁移率随栅电压VGS的变化曲线; (c)亚阈值特性; (d) RF功率50 W的器件三端击穿特性
Fig. 2. Electrical characteristics of GaN UMOSFETs fabricated with RF power of 50, 75 and 135 W (IGS and IDS are gate and drain currents): (a) Transfer characteristics; (b) field-effect channel mobility as a function of gate voltage; (c) subthreshold characteristics; (d) breakdown characteristics.
图 3 采用光刻胶和SiO2作为刻蚀掩模制备出的GaN UMOSFET器件的电学特性曲线 (a)转移特性曲线; (b)沟道场效应迁移率随栅电压的变化曲线; (c)输出特性曲线; (d)亚阈值特性
Fig. 3. Electrical characteristics of GaN UMOSFETs with SiO2 and photoresist as etching masks: (a) Transfer characteristics; (b) field-effect channel mobility vs. gate voltage; (c) output
$ I\text-V $ characteristics; (d) subthreshold characteristics.图 4 (a)采用不同刻蚀掩模后U型槽的刻蚀形貌; (b)刻蚀掩模侧壁的高能粒子反射现象
Fig. 4. (a) Etching morphology of the U-shape trench using different etching masks; (b) high-energy ion reflection at the sidewall of etching masks.
图 5 光刻胶掩模的样品经U型槽刻蚀后的SEM图像
Fig. 5. SEM image of U-shape trench after dry etching with photoresist etching mask.
表 1 干法刻蚀条件参数(1 Torr = 1.33322 × 102 Pa)
Table 1. Experiment parameters of the dry etching process.
条件 刻蚀气体及流量 RF功率/W ICP功率/W 腔室压强/mTorr 刻蚀掩模 A 24 sccm Cl2, 16 sccm BCl3, 5 sccm Ar 135 500 8 光刻胶(PR) B 75 C 50 D 50 SiO2 PHP网站源码观澜网站开发西乡百姓网标王推广西乡SEO按天计费南山网络营销石岩关键词按天计费龙岗网站搭建惠州关键词按天收费坂田seo优化观澜建站惠州外贸网站建设南联网站搭建坪山SEO按效果付费坂田关键词按天计费罗湖网站推广坪山营销网站南澳关键词按天收费民治网站搭建龙华百度网站优化排名爱联网站制作坪地网站优化按天收费沙井百度网站优化南山外贸网站设计福田外贸网站制作大鹏网站优化按天计费福永建网站观澜网站推广工具沙井网站优化软件盐田网站推广方案石岩seo大浪营销型网站建设歼20紧急升空逼退外机英媒称团队夜以继日筹划王妃复出草木蔓发 春山在望成都发生巨响 当地回应60岁老人炒菠菜未焯水致肾病恶化男子涉嫌走私被判11年却一天牢没坐劳斯莱斯右转逼停直行车网传落水者说“没让你救”系谣言广东通报13岁男孩性侵女童不予立案贵州小伙回应在美国卖三蹦子火了淀粉肠小王子日销售额涨超10倍有个姐真把千机伞做出来了近3万元金手镯仅含足金十克呼北高速交通事故已致14人死亡杨洋拄拐现身医院国产伟哥去年销售近13亿男子给前妻转账 现任妻子起诉要回新基金只募集到26元还是员工自购男孩疑遭霸凌 家长讨说法被踢出群充个话费竟沦为间接洗钱工具新的一天从800个哈欠开始单亲妈妈陷入热恋 14岁儿子报警#春分立蛋大挑战#中国投资客涌入日本东京买房两大学生合买彩票中奖一人不认账新加坡主帅:唯一目标击败中国队月嫂回应掌掴婴儿是在赶虫子19岁小伙救下5人后溺亡 多方发声清明节放假3天调休1天张家界的山上“长”满了韩国人?开封王婆为何火了主播靠辱骂母亲走红被批捕封号代拍被何赛飞拿着魔杖追着打阿根廷将发行1万与2万面值的纸币库克现身上海为江西彩礼“减负”的“试婚人”因自嘲式简历走红的教授更新简介殡仪馆花卉高于市场价3倍还重复用网友称在豆瓣酱里吃出老鼠头315晚会后胖东来又人满为患了网友建议重庆地铁不准乘客携带菜筐特朗普谈“凯特王妃P图照”罗斯否认插足凯特王妃婚姻青海通报栏杆断裂小学生跌落住进ICU恒大被罚41.75亿到底怎么缴湖南一县政协主席疑涉刑案被控制茶百道就改标签日期致歉王树国3次鞠躬告别西交大师生张立群任西安交通大学校长杨倩无缘巴黎奥运
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[1] Uemoto Y, Hikita M, Ueno H, Matsuo H, Ishida H, Yanagihara M, Ueda T, Tanaka T, Ueda D 2007 IEEE Trans. Electron Dev. 54 3393 Google Scholar
[2] Anderson T J, Wheeler V D, Shahin D I, Tadjer M J, Koehler A D, Hobart K D, Christou A, Kub F J, Eddy C R 2016 Appl. Phys. Express 9 071003 Google Scholar
[3] Sun S, Fu K, Yu G, Zhang Z, Song L, Deng X, Qi Z, Li S, Sun Q, Cai Y, Dai J, Chen C, Zhang B 2016 Appl. Phys. Lett. 108 013507 Google Scholar
[4] Wang H, Wang J, Liu J, Li M, He Y, Wang M, Yu M, Wu W, Zhou Y, Dai G 2017 Appl. Phys. Express 10 106502 Google Scholar
[5] Gao J, Jin Y, Xie B, Wen C P, Hao Y, Shen B, Wang M 2018 IEEE Electron Dev. Lett. 39 859 Google Scholar
[6] Ambacher O, Smart J, Shealy J R, Weimann N G, Chu K, Murphy M, Schaff W J, Eastman L F, Dimitrov R, Wittmer L, Stutzmann M, Rieger W, Hilsenbeck J 1999 J. Appl. Phys. 85 3222 Google Scholar
[7] Kambayashi H, Satoh Y, Kokawa T, Ikeda N, Nomura T, Kato S 2011 Solid-State Electron. 56 163 Google Scholar
[8] 崔兴涛, 陈万军, 施宜军, 信亚杰, 李茂林, 王方洲, 周琦, 李肇基, 张波 2019 半导体技术 44 286 Google Scholar
Cui X T, Chen W J, Shi Y J, Xin Y J, Li M L, Wang F Z, Zhou Q, Li Z J, Zhang B 2019 Semiconductor Technology 44 286 Google Scholar
[9] 唐文昕, 郝荣晖, 陈扶, 于国浩, 张宝顺 2018 物理学报 67 198501 Google Scholar
Tang W X, Hao R H, Chen F, Yu G H, Zhang B S 2018 Acta Phys. Sin. 67 198501 Google Scholar
[10] Lin R M, Chu F C, Das A, Liao S Y, Chou S T, Chang L B 2013 Thin Solid Films 544 526 Google Scholar
[11] Russo S, Di Carlo A 2007 IEEE Trans. Electron Dev. 54 1071 Google Scholar
[12] Horio K, Takayanagi H, Nakano H 2006 Phys. Status Solidi 3 2346 Google Scholar
[13] Meneghesso G, Rampazzo F, Kordos P, Verzellesi G, Zanoni E 2007 IEEE Trans. Electron Dev. 53 2932 Google Scholar
[14] Oka T, Ina T, Ueno Y, Nishii J 2015 Appl. Phys. Express 8 054101 Google Scholar
[15] Chowdhury S, Swenson B L, Wong M H, Mishra U K 2013 Semicond. Sci. Technol. 28 074014 Google Scholar
[16] Nie H, Diduck Q, Alvarez B, Edwards A P, Kayes B M, Zhang M, Ye G, Prunty T, Bour D, Kizilyalli I C 2014 IEEE Electron Dev. Lett. 35 939 Google Scholar
[17] Ji D, Chowdhury S 2015 IEEE Trans. Electron Dev. 62 2571 Google Scholar
[18] Otake H, Chikamatsu K, Yamaguchi A, Fujishima T, Ohta H 2008 Appl. Phys. Express 1 011105 Google Scholar
[19] Oka T, Ueno Y, Ina T, Hasegawa K 2014 Appl. Phys. Express 7 021002 Google Scholar
[20] Sun M, Zhang Y, Gao X, Palacios T 2017 IEEE Electron Dev. Lett. 38 509 Google Scholar
[21] Zhang Y, Sun M, Perozek J, Liu Z, Zubair A, Piedra D, Chowdhury N, Gao X, Shepard K, Palacios T 2018 IEEE Electron Dev. Lett. 40 75 Google Scholar
[22] Gupta C, Chan S H, Lund C, Agarwal A, Koksaldi O S, Liu J, Enatsu Y, Keller S, Mishra U K 2016 Appl. Phys. Express 9 121001 Google Scholar
[23] Fujishima T, Otake H, Ohta H 2008 Appl. Phys. Lett. 92 243505 Google Scholar
[24] Wang Q, Jiang Y, Zhang J, Kawaharada K, Li L, Wang D, Ao J P 2015 Semicond. Sci. Technol. 30 065004 Google Scholar
[25] 施罗德 D K 著 (刘爱民等 译) 1998 半导体材料与器件表征技术 (大连: 大连理工大学出版社) 第284−286页
Schroder D K (translated by Liu A M) 1998 Semiconductor Material and Device Characterization (Dalian: Dalian University of Technology Press) pp284−286 (in Chinese)
[26] Gupta C, Chan S, Pasayat S, Keller S, Mishra U 2019 J. Appl. Phys. 125 124101 Google Scholar
[27] Narita T, Kikuta D, Takahashi N, Kataoka K, Kimoto Y, Uesugi T, Kachi T, Sugimoto M 2011 Phys. Status Solidi A 208 1541 Google Scholar
[28] Kodama M, Sugimoto M, Hayashi E, Soejima N, Ishiguro O, Kanechika M, Itoh K, Ueda H, Uesugi T, Kachi T 2008 Appl. Phys. Express 1 021104 Google Scholar
[29] Flemish J R, Xie K 1994 Appl. Phys. Lett. 64 2315 Google Scholar
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