Integration of Inkjet Printing Technology with CMOS System-on-Chip

• Main Authors: Chang-Hung Lee, 李長鴻
• Other Authors: Chih-Ting Lin
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/02055494615556652210

博士 === 國立臺灣大學 === 電子工程學研究所 === 102 === The organic electronic devices provide promising features with the development of organic materials. For example, the organic materials with bio-compatible or gas/chemical sensing function could be utilized in the applications for bio or sensor networks. However, compare to silicon IC, the operation speed of organic circuits is still limited by the materials and fabrication processes. If the organic devices could be integrated with silicon devices on the chip level, we could take both strengths from organic and silicon electronic devices, and build a highly-integrated, multi-functional novel IC. In this dissertation, a heterogeneous integration technique which vertically connects organic electronic devices and CMOS IC is demonstrated by non-contact inkjet printing process. By inkjet printing technique, more integrated devices could be realized with lower power consumption, higher integration, and save more chip area. First, an all-inkjet-printed organic thin-film transistor (OTFT) with double insulator layer is proposed. By using the double-layer structure with different dielectric materials, the threshold-voltage of OTFT can be adjusted. The threshold-voltage shift can be controlled by changing the composition of dielectric layers. That is, an enhancement-mode OTFT can be converted to a depletion-mode OTFT by selectively printing additional dielectric layers to form a high-k/low-k double-layer structure. The threshold-voltages of the OTFTs shift between -13 V and 10 V. This study demonstrates an additional design parameter for organic electronics manufactured using inkjet printing technology. Than an inkjet printable humidity sensing material, PEDOT:PSS, is developed to improve the fabrication capability. Besides, different kinds of nanoparticles, SiO2 and aluminum zinc oxide (AZO), are also employed to enhance the stability and sensitivity to humidity sensing. Based on experimental results, the sensitivity can be improved by 100%; the stability can also be noticeably enhanced. To understand the sensing mechanism, a series of material analysis method is executed. Based on the material investigations, the sensing enhancement is due to physical adsorption of the blending nanoparticles. This work proposes a high sensitivity and low cost humidity sensing material for different applications Because of the energy barrier between conductive polymer and metal, most of the metal/organic interfaces are difficult to form an ohmic contact, which could impede the integration of conductive polymer devices and CMOS chip. An inkjet-printed gold nanoparticle film as a buffer layer could modify the aluminum electrode and conquered the contact barrier. The improvement of contact resistance between nano-gold-modified aluminum electrodes and PEDOT:PSS film is experimentally tested. Finally, a low-power, wide-dynamic-range integrated humidity sensing chip is implemented using a printable polymer sensing material with an on-chip pulse-width-modulation interface circuit. By using the inkjet printing technique, PEDOT:PSS that has humidity sensing features can be printed onto the top metal layer of a 0.35 μm CMOS IC. The developed printing-on-chip humidity sensor achieves a heterogeneous three dimensional sensor system-on-chip architecture. The humidity sensing of the implemented printing-on-chip sensor system is experimentally tested. The power consumption keeps only 154 μW. This printing-on-chip sensor provides a practical solution to fulfill an miniaturized sensing system for the applications in healthcare, indoor-air-quality monitoring, and machine-to-machine networks.