标题: 以二氧化铪为闸极介电层及镍-锑化镓合金为源/汲极之锑化镓通道P型场效电晶体制作
Fabrication of GaSb Channel PMOSFETs with HfO2 as Gate Dielectric and Ni-GaSb Alloy as Source/Drain
作者: 柯俊宇
简昭欣
林炯源
Ko, Chun-Yu
Chien, Chao-Hsin
Lin, Chiung-Yuan
电子研究所
关键字: 锑化镓;P型场效电晶体;氢气电浆处理;二氧化铪;GaSb;PMOSFET;hydrogen plasma treatment;HfO2
公开日期: 2016
摘要: 在此篇论文中,我们首先于原子层沉积化学气相沉积(atomic layer deposition, ALD)之前利用氢气电浆处理制作出以二氧化锆为介电材料之锑化镓p型金属-氧化物-半导体电容 (pMOSCAP)。我们发现在做氢气电浆处理之后不仅电容调节(modulation of capacitance)提升其漏电流也得以被抑制住。我们使用博戈隆方法(Berglund method)及电导方法(conductance method)萃取介面能态密度。经过组成气体退火(forming gas anneal)之后介面能态密度来到约5x1012 eV-1cm-2。透过X射线光电子能谱仪(XPS),我们瞭解到氢电浆处理能够去除锑化镓的原生氧化层。此外,我们发现一旦使用氢电浆处理后锑化镓的表面变得平滑。
接着,我们成功利用快速升温退火炉(RTA)于250℃退火1分钟成功形成镍-锑化镓合金。我们在镍-锑化镓合金/n型锑化镓接面的电性发现强烈的萧特基行为(Schottky behavior),有着高开关电流比(约103)及低理想因子(约1.2)。然而,较大的接面逆向电流在高退火温度或长退火时间下被发现。当退火温度达到350℃以上时,不同晶向的锑化镍形成并且也发现成核现象,导致大的接面漏电流。锑化镍也会在250℃退火时间超过5分钟下形成。此外,我们发现镍、镓和锑在退火过程中会扩散。
最后,我们成功展示以二氧化铪为闸极介电材料及镍-锑化镓为源极和汲极之锑化镓通道p型场效电晶体(pMOSFET)。虽然源极电流的开关电流比达到将近4个数量级,我们也发现因大的接面漏电流而使汲极开关比极低。此外,透过分离电容法(split CV method)萃取出极低的电洞迁移率 (~22cm2V-1s-1)。另外,我们也讨论p型金氧半场效电晶体制程的缺点,问题及取舍。
In this thesis, we firstly fabricated HfO2/GaSb p-MOSCAPs by utilizing hydrogen plasma treatment prior to HfO2 deposition. We found that not only modulation of capacitance was increased but also leakage current was suppressed after performing hydrogen plasma treatment. We used Berglund method and conductance method to extract interface states density (Dit). Dit value of 5x1012 eV-1cm-2 was achieved after performing forming gas annealing. By X-ray photoelectron spectroscopy (XPS), we realized that the native oxides of GaSb could be eliminated by hydrogen plasma treatment. Moreover, as confirmed in atomic force microscopy (AFM), we found that the surface of GaSb was smoother once hydrogen plasma treatment was applied.
Secondly, we successfully formed Ni-GaSb alloy at 250℃ for 1 minute by rapid thermal annealing (RTA). Strong Schottky behavior was observed in the I-V characteristic of Ni-GaSb/n-GaSb junction, which had large Ion/Ioff (~103 ) and low ideal factor (~1.2). Nevertheless, large junction reverse current was observed at high annealing temperature or long annealing time. As annealing temperature reached higher than 350℃, various crystal orientation of NiSb was formed and also agglomeration was observed, leading to large junction leakage current. NiSb was formed at 250℃ for annealing time longer than 5 minutes as well. Besides, we found that Ni, Ga and Sb would diffuse during annealing process.
Finally, we successfully fabricated GaSb channel PMOSFETs with HfO2 as gate dielectric as well as Ni-GaSb as S/D. Although on/off ratio (~4 orders) of source current was achieved, extremely low on/off ratio of drain current was also observed owing to large junction leakage current. Besides, ultra-low hole mobility (~22cm2V-1s-1) was extracted by means of split CV method. Also, we discussed the drawbacks, problems and trade-off of the process we adopted for fabricating PMOSFETs.
URI: http://etd.lib.nctu.edu.tw/cdrfb3/record/nctu/#GT070350103
http://hdl.handle.net/11536/139874
显示于类别:Thesis