多晶硅TFT后氢化处理的研究
摘要
多晶硅薄膜晶体管(p-Si TFT)液晶显示器可以实现高分辨率、高集成度、同时有效降低显示器的功耗,因而成为目前平板显示领域主要研究方向;而以横向晶化多晶硅为有源层的TFT由于在导电方向有更少的晶界、更低的金属杂质污染、更高的载流子迁移率而成为目前有源矩阵液晶显示领域、投影显示、OLED显示等领域研究的热点。
多晶硅薄膜晶粒间界存在大量的悬挂键与缺陷,形成高密度陷阱.晶粒间的杂质电离产生的载流子首先被陷阱浮获,减少了参与导电的自由载流子的数目.陷阱在浮获载流子之前是电中性的,但是在俘获载流子之后就带电了,在其周围形成一个多子势区,阻挡载流子从一个晶粒向另一个晶粒运动,导致载流子迁移率下降,导致TFT的电学性能下降。而通过氢化可以大大降低多晶硅薄膜晶粒边界中的悬挂键和界面陷阱,从而显著提高TFT的场效应迁移率和开态电流,减少关态电流,提高TFT的电学性能。
常规的氢化工艺是在TFT全部完成后再进行氢化处理的。那样不仅氢化时间很长而且氢离子需要穿过多层薄膜(钝化层、栅氧化层、源漏极电极接触区)才能够进入沟道层,这样就需要氢化设备提供大的功率密度,从而使得设备成本增加。本实验在沉积栅氧化层后立即用PECVD进行多晶硅的氢化处理。这样使得实验参数易于控制。并且在后面工艺中没有高温工艺,这样就使得氢化后进入多晶硅的氢不会因为高温而逸出。
在利用PECVD设备进行等离子氢化的实验中,氢化参数决定了最终的氢化效果。主要的氢化参数有射频功率、氢气流量、样品温度、处理时间。本文的工作宗旨在研究探索PECVD方法中氢化参数对氢化效果的影响,制备出性能优良的TFT。本实验通过系统的改变氢化参数,氢化出一些列的TFT。对各种条件下氢化的TFT进行测量其阈值电压和开关比。并对其实验数据和现象进行分析和讨论,比较系统的总结了主要氢化参数对TFT电学性能的影响作用。实验最后,通过对氢化参数的优化选择,获得较佳的工艺条件,并在此工艺条件下制备出性能优良的TFT。
Poly-crystallization silicon thin film transistor (p-Si TFT) addressing liquid crystal display has been currently the research and development focus in the field of flat panel displays, as it is most feasible approach to high resolution, high integration and low power consumption as a result of its high aperture ration. There are less number interface of the crystal grain,lower metal impurity and higher mobility in the electric current director, the MILC P-Si TFT has been the research focus in the fields of AMLCD, projection display, OLED etc.
There are vast dangling bonds and bug. they form high-density trap. Carrier will be capture by trap, the number of electric carrier will decrease. The trap hold back carrier to move from crystal to other crystal. It influences the electrical properties of TFT. We can lessen the dangling bonds and bug in order to improve the Ion/Ioff、Vth by hydrogenation.
In general, hydrogenation is prepared after completing of TFT, in this way, we need more radio frequency power and time, so the cost of hydrogenation will raise. In this experiment, we prepare hydrogenation by PECVD after deposition of silicon nitride thin film for gate insulator of TFT. In this way, parameters are prone to control, and hydrogenation ion will not escape without high temperature.
In the process of hydrogenation by PECVD. Hydrogenation parameters strongly influence the properties of hydrogenation. The key hydrogenation parameters are radio frequency power, reactant gas ration, temperature, time. The motive of this paper is to investigate the relationship between hydrogenation parameters and its properties in order to prepare excellent TFT. We prepare some TFT and test their Ion/Ioff、Vth. By analyzing the data and phenomena of experimentation,The influence of Hydroge- nation parameters on the electrical properties of TFT is systematically discussed. At last ,TFT with excellent electrical properties is prepared under the relatively optimum parameters.
多晶硅薄膜晶粒间界存在大量的悬挂键与缺陷,形成高密度陷阱.晶粒间的杂质电离产生的载流子首先被陷阱浮获,减少了参与导电的自由载流子的数目.陷阱在浮获载流子之前是电中性的,但是在俘获载流子之后就带电了,在其周围形成一个多子势区,阻挡载流子从一个晶粒向另一个晶粒运动,导致载流子迁移率下降,导致TFT的电学性能下降。而通过氢化可以大大降低多晶硅薄膜晶粒边界中的悬挂键和界面陷阱,从而显著提高TFT的场效应迁移率和开态电流,减少关态电流,提高TFT的电学性能。
常规的氢化工艺是在TFT全部完成后再进行氢化处理的。那样不仅氢化时间很长而且氢离子需要穿过多层薄膜(钝化层、栅氧化层、源漏极电极接触区)才能够进入沟道层,这样就需要氢化设备提供大的功率密度,从而使得设备成本增加。本实验在沉积栅氧化层后立即用PECVD进行多晶硅的氢化处理。这样使得实验参数易于控制。并且在后面工艺中没有高温工艺,这样就使得氢化后进入多晶硅的氢不会因为高温而逸出。
在利用PECVD设备进行等离子氢化的实验中,氢化参数决定了最终的氢化效果。主要的氢化参数有射频功率、氢气流量、样品温度、处理时间。本文的工作宗旨在研究探索PECVD方法中氢化参数对氢化效果的影响,制备出性能优良的TFT。本实验通过系统的改变氢化参数,氢化出一些列的TFT。对各种条件下氢化的TFT进行测量其阈值电压和开关比。并对其实验数据和现象进行分析和讨论,比较系统的总结了主要氢化参数对TFT电学性能的影响作用。实验最后,通过对氢化参数的优化选择,获得较佳的工艺条件,并在此工艺条件下制备出性能优良的TFT。
Poly-crystallization silicon thin film transistor (p-Si TFT) addressing liquid crystal display has been currently the research and development focus in the field of flat panel displays, as it is most feasible approach to high resolution, high integration and low power consumption as a result of its high aperture ration. There are less number interface of the crystal grain,lower metal impurity and higher mobility in the electric current director, the MILC P-Si TFT has been the research focus in the fields of AMLCD, projection display, OLED etc.
There are vast dangling bonds and bug. they form high-density trap. Carrier will be capture by trap, the number of electric carrier will decrease. The trap hold back carrier to move from crystal to other crystal. It influences the electrical properties of TFT. We can lessen the dangling bonds and bug in order to improve the Ion/Ioff、Vth by hydrogenation.
In general, hydrogenation is prepared after completing of TFT, in this way, we need more radio frequency power and time, so the cost of hydrogenation will raise. In this experiment, we prepare hydrogenation by PECVD after deposition of silicon nitride thin film for gate insulator of TFT. In this way, parameters are prone to control, and hydrogenation ion will not escape without high temperature.
In the process of hydrogenation by PECVD. Hydrogenation parameters strongly influence the properties of hydrogenation. The key hydrogenation parameters are radio frequency power, reactant gas ration, temperature, time. The motive of this paper is to investigate the relationship between hydrogenation parameters and its properties in order to prepare excellent TFT. We prepare some TFT and test their Ion/Ioff、Vth. By analyzing the data and phenomena of experimentation,The influence of Hydroge- nation parameters on the electrical properties of TFT is systematically discussed. At last ,TFT with excellent electrical properties is prepared under the relatively optimum parameters.
引文
[1] Gray G.W, Harrison K.J, Nash, Electron.Lett, 1973, 9:130
[2] Scheffer T J, Nehring J, Appl.Phys.Lett. 1984,45:10-21
[3] P.Weimer: Pro.IRE, June, 1962,14:62
[4] A.Fischer, T.Brody, and W.Escott: IEEE Vonf. Display Devices,1972,8: 64
[5] T.Brody, J.Asars, and G.Dixon: SID, 73 Digest,1973,2:179
[6] P.Le.Comber, W.Spear, and A.Ghaith: Electronics Lett, 1979,15:180
[7] A.Snell, K.Mackenzie, W.Spear, and P.Le comber: ESSDRC,80 Euro physics Conf.,1980, 3:99
[8] S.Morozumi, K.Oguchi, S.yazawa, T.Kodaira, H.Ohshima. and T.Mano: SID,83, Digiest, 1983,156
[9] 刘永智,液晶显示技术,成都:电子科技大学出版社,2000,185-215
[10] T.Hirai, K.Miyake, et.al. Japan Display,1999,9:229
[11] J.G.Simmons, Phys.Rev.1967,155-657
[12]W.C.Omara, et al. Liquid crystal display; Manufacturing Science and Technology. New York, 1993:1-46
[13] H.Ohshima, et al. Conf. Record 1994 Int. Display Conf, 1994:26
[14] I-Wei Wu. Poly-Si TFT Technology for High Resolution AM-LCDs,In:96 全国平板显示学术会议.北京.1996:6-9
[15]张坤,多晶硅薄膜场效应结构的晶粒间界能态分布:[硕士学位论文].广州:暨南大学,2003
[16]徐重阳,实现多晶硅薄膜等离子氢化的新工艺,光电子技术,2000,80:179-182
[17]懂会宁.非晶硅的二步快速退火固相晶化,四川大学学报, 1995, 0l:95-97
[18]邱法斌.准分子激光烧结玻璃衬底上多晶硅薄膜材料的制备.液晶与显示,2001,03:170-174
[19]卓铭.金属 Ni 诱导横向晶化的结构及工艺进程的优化.半导体学报,2002,11:1217-1223
[20]刘永智,杨开愚等. 液晶显示技术. 成都:电子科技大学出版社,2000.173-174
[21]康华光. 电子技术基础. 北京:高等教育出版社,1998.140-145
[22]耿新华,多晶硅薄膜后氢化的研究,光电子技术,1995,15:154-158
[23]王玉林,非晶硅光脉冲辅助金属诱导横向晶化的研究:[硕士学位论文].成都:电子科技大学.2005
[24]张化福,TFT 栅绝缘层用氮化硅薄膜的研究:[硕士学位论文].成都:电子科技大学.2005
[25]陈家伟,非晶硅薄膜的湿法刻蚀研究:[学士学位论文].成都:电子科技大学.2005
[26]Kamins T I, MarcouxPJ. Hydrogenation of transistors fabricated in polycrystalline-silicon films.IEL Electron Device Letters 1980,1:159-161
[27]Singh H J,Sarasw at J D,Mcvittie S J P et al Hydrogenation by ion implantation for scaled SOIPMOS transistors EI Electron Device Letters,1985;6:139-141
[2] Scheffer T J, Nehring J, Appl.Phys.Lett. 1984,45:10-21
[3] P.Weimer: Pro.IRE, June, 1962,14:62
[4] A.Fischer, T.Brody, and W.Escott: IEEE Vonf. Display Devices,1972,8: 64
[5] T.Brody, J.Asars, and G.Dixon: SID, 73 Digest,1973,2:179
[6] P.Le.Comber, W.Spear, and A.Ghaith: Electronics Lett, 1979,15:180
[7] A.Snell, K.Mackenzie, W.Spear, and P.Le comber: ESSDRC,80 Euro physics Conf.,1980, 3:99
[8] S.Morozumi, K.Oguchi, S.yazawa, T.Kodaira, H.Ohshima. and T.Mano: SID,83, Digiest, 1983,156
[9] 刘永智,液晶显示技术,成都:电子科技大学出版社,2000,185-215
[10] T.Hirai, K.Miyake, et.al. Japan Display,1999,9:229
[11] J.G.Simmons, Phys.Rev.1967,155-657
[12]W.C.Omara, et al. Liquid crystal display; Manufacturing Science and Technology. New York, 1993:1-46
[13] H.Ohshima, et al. Conf. Record 1994 Int. Display Conf, 1994:26
[14] I-Wei Wu. Poly-Si TFT Technology for High Resolution AM-LCDs,In:96 全国平板显示学术会议.北京.1996:6-9
[15]张坤,多晶硅薄膜场效应结构的晶粒间界能态分布:[硕士学位论文].广州:暨南大学,2003
[16]徐重阳,实现多晶硅薄膜等离子氢化的新工艺,光电子技术,2000,80:179-182
[17]懂会宁.非晶硅的二步快速退火固相晶化,四川大学学报, 1995, 0l:95-97
[18]邱法斌.准分子激光烧结玻璃衬底上多晶硅薄膜材料的制备.液晶与显示,2001,03:170-174
[19]卓铭.金属 Ni 诱导横向晶化的结构及工艺进程的优化.半导体学报,2002,11:1217-1223
[20]刘永智,杨开愚等. 液晶显示技术. 成都:电子科技大学出版社,2000.173-174
[21]康华光. 电子技术基础. 北京:高等教育出版社,1998.140-145
[22]耿新华,多晶硅薄膜后氢化的研究,光电子技术,1995,15:154-158
[23]王玉林,非晶硅光脉冲辅助金属诱导横向晶化的研究:[硕士学位论文].成都:电子科技大学.2005
[24]张化福,TFT 栅绝缘层用氮化硅薄膜的研究:[硕士学位论文].成都:电子科技大学.2005
[25]陈家伟,非晶硅薄膜的湿法刻蚀研究:[学士学位论文].成都:电子科技大学.2005
[26]Kamins T I, MarcouxPJ. Hydrogenation of transistors fabricated in polycrystalline-silicon films.IEL Electron Device Letters 1980,1:159-161
[27]Singh H J,Sarasw at J D,Mcvittie S J P et al Hydrogenation by ion implantation for scaled SOIPMOS transistors EI Electron Device Letters,1985;6:139-141