Selective Deposition of C-axis Oriented Pb 5 Ge 3 O 11 on the Patterned High k Gate Oxide by MOCVD Processes
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Selective Deposition of C-axis Oriented Pb5Ge3O11 on the Patterned High k Gate Oxide by MOCVD Processes Tingkai Li, Sheng Teng Hsu, Bruce Ulrich, Dave Evans Sharp Laboratory of America, Inc. 5700 NW Pacific Rim Blvd. Camas, WA 98607 [email protected] ABSTRACT For the high density FeRAM applications, the integration process-induces damages such as etching damage that degrades the properties of FRAM devices and the high surface roughness of ferroelectric thin film that results in the difficulty for alignment are critical issues. In order to solve these problems, selective deposition process is developed to simplify the integration processes and improve the properties of FeRAM memory devices. Based on the differential deposition rates of ferroelectric materials on high-k oxide and silicon dioxide, we can selectively deposit a c-axis oriented PGO thin film on the patterned high-k oxide such as ZrOx (x=0-2), HfOx (x=0-2), TiO2, and their mixtures other than on SiO2. By patterning the high-k dielectric, the PGO deposition is limited to just the preferred pattern high-k area. SEM, EDX and x-ray measurements further confirm that the c-axis oriented PGO thin films are selectively deposited on the high-k gate oxide other than on the field SiO2 including alignment mark area, which will eliminate the roughness problem for the alignments. Also the etching damage is eliminated since there is no need to etch the PGO film, which improved the properties of FeRAM devices. INTRODUCTION The remanent-polarization states of ferroelectric capacitors have long been of interest for nonvolatile storage of digital data [1-5]. The recent approach to ferroelectric memories has been to integrate the ferroelectric memory capacitor into a random access memory circuit on an integrated circuit to convert semiconductor RAMs to a nonvolatile form. Most of the studies on Ferroelectric Random Access Memories (FeRAM) have been concentrated on the memory structure with one transistor and one capacitor (1T1C), and one transistor (1T) memory devices with MFMIS (Metal/Ferroelectrics/Metal/Insulator/Silicon) and MFIS structures have also been fabricated recently [6-10]. However, for smaller devices and higher density application of FeRAM devices, the ferroelectric thin film are related to the integration process induced damages, which degrades the working function of FeRAM devices [11]. Therefore, we improved the integration processes including damascene structure, selective deposition and chemical mechanical planarization (CMP). For 1T memory devices, C-axis oriented Pb5Ge3O11 thin films showed the very good ferroelectric and electrical properties for the 1T-memory device applications. Extremely high c-axis oriented PGO thin films can be deposited on high k gate oxides, and the working 1T-memory devices with PGO MFIS memory cell have also been fabricated. In this paper, we proposed the selective deposition technologies for c-axis oriented PGO thin films on high k gate oxides including ZrOX (x=0-2), HfOX (x=0-2), TiO2, Al2O3, La2O3 and their mi
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