【摘要】：高性能薄膜晶體管（TFT）背板技術(shù)是以有源驅(qū)動有機發(fā)光二極管（AMOLED）為代表的平板顯示（FPD）產(chǎn)業(yè)的共性技術(shù)和核心技術(shù)，也是FPD產(chǎn)業(yè)提高產(chǎn)品質(zhì)量、降低生產(chǎn)成本的重要環(huán)節(jié)。隨著大尺寸、高分辨、3D顯示技術(shù)的快速發(fā)展，其對TFT背板的要求越來越高。然而，傳統(tǒng)的非晶硅TFT遷移率較低，無法實現(xiàn)高分辨率顯示；多晶硅TFT遷移率高，但其存在生產(chǎn)工藝復(fù)雜、設(shè)備投資高、均勻性差、良品率低等難以克服的問題，實現(xiàn)大面積顯示成本較高；金屬氧化物TFT（MOTFT）近年來備受業(yè)界關(guān)注，其遷移率較高、工藝簡單、成本低，容易實現(xiàn)大面積制備，并且與非晶硅TFT生產(chǎn)線相兼容，成為目前業(yè)界的新焦點。因此，開展對新興的、在FPD產(chǎn)業(yè)上較有應(yīng)用前景的MOTFT的研究工作具有現(xiàn)實的意義。 本論文研究了柵極絕緣材料及其制備工藝。由于柵極絕緣層決定著薄膜晶體管的擊穿電壓、泄漏電流等重要工作參數(shù)，因此獲得高介電常數(shù)、高質(zhì)量的柵極絕緣層顯得極為重要�；诖�，我們開發(fā)出了陽極氧化Al2O3薄膜制備新工藝，在氧化制備過程中使用數(shù)控系統(tǒng)對氧化信號進行編程，研制的Al2O3薄膜具有高介電常數(shù)（~10）、高擊穿電場（~6MV/cm）、低泄漏電流（10-8A/cm2）的優(yōu)點。這種制備方法即避免使用貴重的真空設(shè)備，節(jié)約了成本，又提高了柵介質(zhì)薄膜的大面積均一性，十分適合大尺寸AMOLED顯示屏的制作。 同時，為了解決柵極Al薄膜在高溫下容易產(chǎn)生表面小丘的問題，本論文又研制了基于Al-Nd和Al-Ce合金柵極的陽極氧化Al2O3，以提高Al/Al2O3體系的熱穩(wěn)定性，得到的Nd:Al2O3和Ce:Al2O3絕緣層在高溫下表面平整、膜層致密，完全能夠抑制小丘的形成。研究表明，Nd或Ce會擴散進入到半導體內(nèi)，對MOTFT的器件性能產(chǎn)生重要影響。其中，Ce元素產(chǎn)生電荷陷阱缺陷，嚴重惡化器件的電學性能；Nd元素則能抑制氧空位和雜亂的自由電子，改善器件的電學性能。因此，Nd與金屬氧化物半導體具有較好的兼容性，基于陽極氧化Nd:Al2O3絕緣層的MOTFT在FPD產(chǎn)業(yè)上有較大的應(yīng)用潛力。 由于Al合金柵極的電阻率過高，增加了顯示屏的信號延遲，其無法實現(xiàn)更大尺寸和要求高響應(yīng)速度的視頻顯示。因此，我們發(fā)明了一種埋入式Al柵極結(jié)構(gòu)，僅使用加厚的純Al柵極和輔助的埋入材料（JSR-NN901），，工藝簡單，不增加光刻步驟，即能滿足電阻率的要求，解決了信號延遲的問題，又能提高Al薄膜的熱穩(wěn)定性，抑制了小丘的產(chǎn)生�；诼袢胧紸l柵極的MOTFT展示出了低工作電壓、高遷移率、高電學穩(wěn)定性、高可靠性的特點。這種簡單而有效的工藝技術(shù)很有希望應(yīng)用在大尺寸、高響應(yīng)速度的新型顯示技術(shù)中。 為了獲得低成本、高分辨率的顯示屏，在制備MOTFT源、漏電極的工藝過程中需要采用背溝道刻蝕結(jié)構(gòu)。但是，由于金屬氧化物半導體基本上對各種酸性刻蝕液和干法刻蝕等離子體都很敏感，很容易被腐蝕或受到損傷，因此刻蝕源、漏電極十分困難。經(jīng)過研究，本論文提出了兩種工藝方法：一種是采用弱酸性的H2O2基刻蝕液圖形化源、漏電極，并利用低能量的SF6plasma對背溝道進行修飾；第二種是采用C納米薄膜作為背溝道的緩沖層，此方法不受刻蝕液限制，具有普適性。上述兩種方法均不需要特殊的設(shè)備，且不增加光刻掩膜版次數(shù)，制備出的MOTFT背溝道無損傷，表現(xiàn)出了優(yōu)越的器件性能和良好的電學穩(wěn)定性。其對設(shè)備無要求、低成本、寬工藝窗口的特點使得上述背溝道無損傷的MOTFT制造技術(shù)有很大應(yīng)用潛力替代現(xiàn)有技術(shù)。 結(jié)合上述方法，本論文進一步延伸其應(yīng)用，利用MoO3作為背溝道的電荷存儲層，研制了新型的非易失性存儲器件，所制備的存儲器件具有電荷保留時間長、重復(fù)性高、讀寫時間短、密度高的特點。其可制作全透明存儲器的潛力，使真正的“全透明”顯示屏成為可能。 基于前面對MOTFT新結(jié)構(gòu)、新制備工藝的研究開發(fā)，本論文改進了MOTFT驅(qū)動背板的工藝實現(xiàn)路線，使光刻掩膜版次數(shù)從7次減少到5次，并在此基礎(chǔ)上進行工藝版圖設(shè)計，成功實現(xiàn)了AMOLED顯示屏的制作。最后，結(jié)合使用擁有自主知識產(chǎn)權(quán)的新型半導體材料體系，開發(fā)出了2-7英寸等多款MOTFT驅(qū)動背板，并成功驅(qū)動包括單色、彩色、透明、柔性等顯示屏，實現(xiàn)了基于MOTFT的AMOLED圖像和視頻顯示。因此，MOTFT在AMOLED等新型顯示技術(shù)上的應(yīng)用將會有很大的突破。
[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.
【學位授予單位】：華南理工大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN321.5

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