新型金属氧化物薄膜晶体管的性能研究及工艺开发
发布时间：2018-07-26 13:08
【摘要】：高性能薄膜晶体管（TFT）背板技术是以有源驱动有机发光二极管（AMOLED）为代表的平板显示（FPD）产业的共性技术和核心技术，也是FPD产业提高产品质量、降低生产成本的重要环节。随着大尺寸、高分辨、3D显示技术的快速发展，其对TFT背板的要求越来越高。然而，传统的非晶硅TFT迁移率较低，无法实现高分辨率显示；多晶硅TFT迁移率高，但其存在生产工艺复杂、设备投资高、均匀性差、良品率低等难以克服的问题，实现大面积显示成本较高；金属氧化物TFT（MOTFT）近年来备受业界关注，其迁移率较高、工艺简单、成本低，容易实现大面积制备，并且与非晶硅TFT生产线相兼容，成为目前业界的新焦点。因此，开展对新兴的、在FPD产业上较有应用前景的MOTFT的研究工作具有现实的意义。 本论文研究了栅极绝缘材料及其制备工艺。由于栅极绝缘层决定着薄膜晶体管的击穿电压、泄漏电流等重要工作参数，因此获得高介电常数、高质量的栅极绝缘层显得极为重要。基于此，我们开发出了阳极氧化Al2O3薄膜制备新工艺，在氧化制备过程中使用数控系统对氧化信号进行编程，研制的Al2O3薄膜具有高介电常数（~10）、高击穿电场（~6MV/cm）、低泄漏电流（10-8A/cm2）的优点。这种制备方法即避免使用贵重的真空设备，节约了成本，又提高了栅介质薄膜的大面积均一性，十分适合大尺寸AMOLED显示屏的制作。 同时，为了解决栅极Al薄膜在高温下容易产生表面小丘的问题，本论文又研制了基于Al-Nd和Al-Ce合金栅极的阳极氧化Al2O3，以提高Al/Al2O3体系的热稳定性，得到的Nd:Al2O3和Ce:Al2O3绝缘层在高温下表面平整、膜层致密，完全能够抑制小丘的形成。研究表明，Nd或Ce会扩散进入到半导体内，对MOTFT的器件性能产生重要影响。其中，Ce元素产生电荷陷阱缺陷，严重恶化器件的电学性能；Nd元素则能抑制氧空位和杂乱的自由电子，改善器件的电学性能。因此，Nd与金属氧化物半导体具有较好的兼容性，基于阳极氧化Nd:Al2O3绝缘层的MOTFT在FPD产业上有较大的应用潜力。 由于Al合金栅极的电阻率过高，增加了显示屏的信号延迟，其无法实现更大尺寸和要求高响应速度的视频显示。因此，我们发明了一种埋入式Al栅极结构，仅使用加厚的纯Al栅极和辅助的埋入材料（JSR-NN901），，工艺简单，不增加光刻步骤，即能满足电阻率的要求，解决了信号延迟的问题，又能提高Al薄膜的热稳定性，抑制了小丘的产生。基于埋入式Al栅极的MOTFT展示出了低工作电压、高迁移率、高电学稳定性、高可靠性的特点。这种简单而有效的工艺技术很有希望应用在大尺寸、高响应速度的新型显示技术中。 为了获得低成本、高分辨率的显示屏，在制备MOTFT源、漏电极的工艺过程中需要采用背沟道刻蚀结构。但是，由于金属氧化物半导体基本上对各种酸性刻蚀液和干法刻蚀等离子体都很敏感，很容易被腐蚀或受到损伤，因此刻蚀源、漏电极十分困难。经过研究，本论文提出了两种工艺方法：一种是采用弱酸性的H2O2基刻蚀液图形化源、漏电极，并利用低能量的SF6plasma对背沟道进行修饰；第二种是采用C纳米薄膜作为背沟道的缓冲层，此方法不受刻蚀液限制，具有普适性。上述两种方法均不需要特殊的设备，且不增加光刻掩膜版次数，制备出的MOTFT背沟道无损伤，表现出了优越的器件性能和良好的电学稳定性。其对设备无要求、低成本、宽工艺窗口的特点使得上述背沟道无损伤的MOTFT制造技术有很大应用潜力替代现有技术。 结合上述方法，本论文进一步延伸其应用，利用MoO3作为背沟道的电荷存储层，研制了新型的非易失性存储器件，所制备的存储器件具有电荷保留时间长、重复性高、读写时间短、密度高的特点。其可制作全透明存储器的潜力，使真正的“全透明”显示屏成为可能。 基于前面对MOTFT新结构、新制备工艺的研究开发，本论文改进了MOTFT驱动背板的工艺实现路线，使光刻掩膜版次数从7次减少到5次，并在此基础上进行工艺版图设计，成功实现了AMOLED显示屏的制作。最后，结合使用拥有自主知识产权的新型半导体材料体系，开发出了2-7英寸等多款MOTFT驱动背板，并成功驱动包括单色、彩色、透明、柔性等显示屏，实现了基于MOTFT的AMOLED图像和视频显示。因此，MOTFT在AMOLED等新型显示技术上的应用将会有很大的突破。
[Abstract]:High performance thin film transistor (TFT) backboard technology is the common technology and core technology of the panel display (FPD) industry represented by active drive organic light-emitting diode (AMOLED). It is also an important link in the FPD industry to improve product quality and reduce production cost. With the rapid development of large size, high resolution and 3D display technology, the needs of the TFT backboard However, the traditional amorphous silicon TFT has a low mobility and can not achieve high resolution display; polysilicon TFT has high mobility, but it has a complex production process, high equipment investment, poor uniformity and low yield, which is difficult to overcome in large area. Metal oxide TFT (MOTFT) has been prepared in recent years. Because of its high mobility, simple process, low cost, easy to achieve large area preparation, and compatible with amorphous silicon TFT production line, it has become a new focus in the industry. Therefore, it is of great significance to carry out the research work on the emerging and more promising MOTFT in the FPD industry.
In this paper, the gate insulating material and its preparation technology are studied. Because the gate insulating layer determines the breakdown voltage, leakage current and other important working parameters, it is very important to obtain high dielectric constant and high quality gate insulating layer. Based on this, we have developed a new process for the preparation of anodized Al2O3 film, in oxygen. In the process of preparation, a numerical control system is used to program oxidation signals. The developed Al2O3 films have the advantages of high dielectric constant (~10), high breakdown electric field (~6MV/cm) and low leakage current (10-8A/cm2). This preparation method avoids the use of expensive vacuum equipment, saves the cost, and improves the large area uniformity of the gate dielectric thin film. It is suitable for large size AMOLED display.
At the same time, in order to solve the problem that the gate Al film can easily produce the surface mound at high temperature, this paper also developed an anodic oxidation Al2O3 based on the grid of Al-Nd and Al-Ce alloy to improve the thermal stability of the Al/Al2O3 system. The obtained Nd:Al2O3 and Ce:Al2O3 insulating layers are smooth on the surface at high temperature and the film is dense, which can completely inhibit the formation of the hillock. The study shows that Nd or Ce will spread into the semiconductor, which has an important effect on the performance of MOTFT devices. Among them, the Ce element produces the charge trap defects, which seriously deteriorate the electrical properties of the devices, and the Nd elements can inhibit the oxygen vacancy and the random free electrons and improve the electrical properties of the devices. Therefore, Nd and metal oxide semiconductors have a better performance. Good compatibility, MOTFT based on anodized Nd:Al2O3 insulating layer has great potential in FPD industry.
Because the resistivity of the Al alloy grid is too high and the signal delay of the display screen is increased, it can not realize the larger size and the high response speed video display. Therefore, we have invented an embedded Al gate structure, only using the thickened pure Al gate and the auxiliary embedded material (JSR-NN901), the process is simple without increasing the photolithography step, that is to say, To meet the requirement of resistivity, the problem of signal delay is solved, the thermal stability of Al film can be improved, and the production of the hillock is inhibited. The MOTFT based on the buried Al gate shows the characteristics of low working voltage, high mobility, high electrical stability and high reliability. This simple and effective technology is very promising to be applied in large size, A new display technology with high response speed.
In order to obtain low cost, the high resolution display screen needs to adopt the trench channel etching structure in the process of making the MOTFT source. However, because the metal oxide semiconductor is very sensitive to all kinds of acid etching solution and dry etching plasma, it is very easy to be corroded or damaged. Because of the current source, the leakage pole is ten After research, two methods are proposed in this paper: one is using the weak acid H2O2 based etching solution for graphical source, leakage electrode, and the use of low energy SF6plasma to modify the back channel; the second is the use of C nano thin film as the buffer layer of the back channel. This method is not restricted by the etching solution, and is universally suitable. The two methods do not require special equipment, and do not increase the number of photolithography mask, and the prepared MOTFT back channel has no damage. It shows superior device performance and good electrical stability. It has great potential for the MOTFT manufacturing technology with no damage to the back channel, with the advantages of no requirement, low cost and wide process window. Replace the existing technology.
Combined with the above method, this paper further extends its application. Using MoO3 as the charge storage layer of the back channel, a new nonvolatile storage device has been developed. The memory parts prepared have the characteristics of long charge retention time, high repetition, short reading and writing time and high density. It can make the full transparent memory potential and make the real "whole". Transparent "display" is possible.
Based on the research and development of the new MOTFT structure and new preparation technology, this paper improved the process of realizing the process of the MOTFT drive backboard, reducing the number of photolithography mask from 7 times to 5 times. On this basis, the process layout was designed and the production of the AMOLED display was successfully realized. Finally, a new type of independent intellectual property rights was used. The semiconductor material system has developed a number of MOTFT driver backboards, such as 2-7 inches, and successfully drive the display of MOTFT based AMOLED images and video displays, including monochrome, color, transparent, flexible, and so on. Therefore, the application of MOTFT in the new display technology such as AMOLED will be a great breakthrough.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN321.5
本文编号：2146111
[Abstract]:High performance thin film transistor (TFT) backboard technology is the common technology and core technology of the panel display (FPD) industry represented by active drive organic light-emitting diode (AMOLED). It is also an important link in the FPD industry to improve product quality and reduce production cost. With the rapid development of large size, high resolution and 3D display technology, the needs of the TFT backboard However, the traditional amorphous silicon TFT has a low mobility and can not achieve high resolution display; polysilicon TFT has high mobility, but it has a complex production process, high equipment investment, poor uniformity and low yield, which is difficult to overcome in large area. Metal oxide TFT (MOTFT) has been prepared in recent years. Because of its high mobility, simple process, low cost, easy to achieve large area preparation, and compatible with amorphous silicon TFT production line, it has become a new focus in the industry. Therefore, it is of great significance to carry out the research work on the emerging and more promising MOTFT in the FPD industry.
In this paper, the gate insulating material and its preparation technology are studied. Because the gate insulating layer determines the breakdown voltage, leakage current and other important working parameters, it is very important to obtain high dielectric constant and high quality gate insulating layer. Based on this, we have developed a new process for the preparation of anodized Al2O3 film, in oxygen. In the process of preparation, a numerical control system is used to program oxidation signals. The developed Al2O3 films have the advantages of high dielectric constant (~10), high breakdown electric field (~6MV/cm) and low leakage current (10-8A/cm2). This preparation method avoids the use of expensive vacuum equipment, saves the cost, and improves the large area uniformity of the gate dielectric thin film. It is suitable for large size AMOLED display.
At the same time, in order to solve the problem that the gate Al film can easily produce the surface mound at high temperature, this paper also developed an anodic oxidation Al2O3 based on the grid of Al-Nd and Al-Ce alloy to improve the thermal stability of the Al/Al2O3 system. The obtained Nd:Al2O3 and Ce:Al2O3 insulating layers are smooth on the surface at high temperature and the film is dense, which can completely inhibit the formation of the hillock. The study shows that Nd or Ce will spread into the semiconductor, which has an important effect on the performance of MOTFT devices. Among them, the Ce element produces the charge trap defects, which seriously deteriorate the electrical properties of the devices, and the Nd elements can inhibit the oxygen vacancy and the random free electrons and improve the electrical properties of the devices. Therefore, Nd and metal oxide semiconductors have a better performance. Good compatibility, MOTFT based on anodized Nd:Al2O3 insulating layer has great potential in FPD industry.
Because the resistivity of the Al alloy grid is too high and the signal delay of the display screen is increased, it can not realize the larger size and the high response speed video display. Therefore, we have invented an embedded Al gate structure, only using the thickened pure Al gate and the auxiliary embedded material (JSR-NN901), the process is simple without increasing the photolithography step, that is to say, To meet the requirement of resistivity, the problem of signal delay is solved, the thermal stability of Al film can be improved, and the production of the hillock is inhibited. The MOTFT based on the buried Al gate shows the characteristics of low working voltage, high mobility, high electrical stability and high reliability. This simple and effective technology is very promising to be applied in large size, A new display technology with high response speed.
In order to obtain low cost, the high resolution display screen needs to adopt the trench channel etching structure in the process of making the MOTFT source. However, because the metal oxide semiconductor is very sensitive to all kinds of acid etching solution and dry etching plasma, it is very easy to be corroded or damaged. Because of the current source, the leakage pole is ten After research, two methods are proposed in this paper: one is using the weak acid H2O2 based etching solution for graphical source, leakage electrode, and the use of low energy SF6plasma to modify the back channel; the second is the use of C nano thin film as the buffer layer of the back channel. This method is not restricted by the etching solution, and is universally suitable. The two methods do not require special equipment, and do not increase the number of photolithography mask, and the prepared MOTFT back channel has no damage. It shows superior device performance and good electrical stability. It has great potential for the MOTFT manufacturing technology with no damage to the back channel, with the advantages of no requirement, low cost and wide process window. Replace the existing technology.
Combined with the above method, this paper further extends its application. Using MoO3 as the charge storage layer of the back channel, a new nonvolatile storage device has been developed. The memory parts prepared have the characteristics of long charge retention time, high repetition, short reading and writing time and high density. It can make the full transparent memory potential and make the real "whole". Transparent "display" is possible.
Based on the research and development of the new MOTFT structure and new preparation technology, this paper improved the process of realizing the process of the MOTFT drive backboard, reducing the number of photolithography mask from 7 times to 5 times. On this basis, the process layout was designed and the production of the AMOLED display was successfully realized. Finally, a new type of independent intellectual property rights was used. The semiconductor material system has developed a number of MOTFT driver backboards, such as 2-7 inches, and successfully drive the display of MOTFT based AMOLED images and video displays, including monochrome, color, transparent, flexible, and so on. Therefore, the application of MOTFT in the new display technology such as AMOLED will be a great breakthrough.
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN321.5
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