Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2001-03-28
2002-08-27
Wojciechowicz, Edward (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S410000, C257S412000
Reexamination Certificate
active
06441417
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a single c-axis Lead Germanium Oxide (PGO) thin film on an insulator layer for non-volatile memory applications and methods of making the same and, more particularly, to a PGO thin film on a Zirconium Oxide (ZrO
2
) insulator for ferroelectric random access memory (FeRAM) and dynamic random access memory (DRAM) applications.
BACKGROUND OF THE INVENTION
Lead Germanium Oxide (PGO or Pb
5
Ge
3
O
11
) is a well-known ferroelectric material. Pure c-axis oriented PGO thin films have been successfully grown on Iridium (Ir), Platinum (Pt), Platinum/Iridium (Pt/Ir) and Iridium-Tantalum-Oxygen (Ir—Ta—O) conductive electrodes. These structures can be used for metal ferroelectric metal oxide semiconductor (MFMOS) single transistor memory applications.
Ferroelectric devices have also been manufactured with SrBi
2
Ta
2
O
9
(SBT). Unlike the ferroelectric material SBT, which exhibits ferroelectric properties with a polycrystalline structure, PGO only exhibits ferroelectric properties when it is c-axis oriented. However, it is rather difficult to grow single-phase c-axis PGO films on insulators because PGO films usually exhibit amorphous or polycrystalline structure.
Metal ferroelectric semiconductor field effect transistors (MFSFET) are an attractive alternative to MFMOS. However, a strong interaction between the PGO film and the Silicon precludes the fabrication of such devices using a PGO ferroelectric layer. Metal ferroelectric insulator semiconductor field effect transistors (MFISFET) have also been investigated because their structure is simpler than that of MFMOS structures. However, heretofore, good insulator films for fabrication of MFISFET devices, which include a PGO ferroelectric layer, have not been found. Accordingly, there is a need for finding a good insulator film that allows for the fabrication of MFISFET devices having a PGO ferroelectric layer.
SUMMARY OF THE INVENTION
The invention comprises a new thin film structure, including a single-phase c-axis PGO film on an insulator, such as ZrO
2
, for metal ferroelectric insulator semiconductor single transistor non-volatile memory applications. This PGO-on-insulator structure can also be used in capacitors, pyroelectric infrared sensors, optical displays, optical switches, piezoelectric transducers, and surface acoustic wave devices.
Accordingly, an object of the invention is to provide a MFIS transistor structure including a PGO ferroelectric film.
Another object of the invention is to provide a MFIS transistor structure including a ZrO
2
insulator film.
A further object of the invention is to provide a MFIS transistor structure including a PGO ferroelectric layer on an insulator layer.
REFERENCES:
patent: 6190925 (2001-02-01), Li et al.
Kanashima, Takeshi, Analysis of High Frequency Capacitance-Voltage Characteristics of Metal-Ferroelectrics-Insulator-Silicon Structure, Jpn. J. Appl. Phys. 38 (1999) 2044.
Lee, Won-Jae, Electrical Properties of SrBi2Ta2Da/Insulator/Si Structures with Various Insulators, Jpn. J. Appl. Phys. 38 (1999) 2039.
Hirai, Tadahiko, Preparation of SrBi2Ta2Da Film at low Temperatures and Fabrication of a Metal/Ferroelectric/Insurlator/Semiconductor Field Effect Transistor Using A1/SrBi2TaDq/Ce D2/Si (IDO) Structures, Jpn. J. Appl. Phys. 36 (1997) 5908.
Hirai, Tadahiko, Preparation of SrBi2Ta2Da Film at low Temperatures and Fabrication of a Metal/Ferroelectric/Insurlator/Semiconductor Field Effect Transistor Using A1/SrBi2TaDa/Ce D2/Si (IDO) Structures, Jpn. J. Appl. Phys. 36 (1997) 5908.
Hsu Sheng Teng
Ma Yanjun
Maa Jer-Shen
Zhang Fengyan
Zhuang Wei-Wei
Krieger Scott C.
Rabdau Matthew D.
Ripma David C.
Sharp Laboratories of America Inc.
Wojciechowicz Edward
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