Semiconductor device manufacturing: process – Making field effect device having pair of active regions... – Having insulated gate
Reexamination Certificate
2003-07-01
2004-08-03
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Making field effect device having pair of active regions...
Having insulated gate
C257S002000, C257S003000, C257S004000, C257S005000, C257S041000, C257S050000, C257S300000, C365S108000, C365S119000, C365S120000, C365S163000
Reexamination Certificate
active
06770524
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to programmable memory devices.
2. Background
Typical memory applications include dynamic random access memory (DRAM), static random access memory (SRAM), erasable programmable read only memory (EPROM), and electrically erasable programmable read only memory (EEPROM).
Solid state memory devices typically employ micro-electronic circuit elements for each memory bit (e.g., one to four transistors per bit) in memory applications. Since one or more electronic circuit elements are required for each memory bit, these devices may consume considerable chip “real estate” to store a bit of information, which limits the density of a memory chip. The primary “non-volatile” memory element of these devices, such as an EEPROM, typically employ a floating gate field effect transistor device that has limited re-programmability and which holds a charge on the gate of field effect transistor to store each memory bit. These classes of memory devices are also relatively slow to program.
Phase change memory devices use phase change materials, i.e., materials that can be electrically switched between a generally amorphous and a generally crystalline state, for electronic memory application. One type of memory element originally developed by Energy Conversion Devices, Inc. of Troy, Mich. utilizes a phase change material that can be, in one application, electrically switched between a structural state of generally amorphous and generally crystalline local order or between different detectable states of local order across the entire spectrum between completely amorphous and completely crystalline states. Typical materials suitable for such application include those utilizing various chalcogenide elements. These electrical memory devices typically do not use field effect transistor devices, but comprise, in the electrical context, a monolithic body of thin film chalcogenide material. As a result, very little chip real estate is required to store a bit of information, thereby providing for inherently high density memory chips. The state change materials are also truly non-volatile in that, when set in either a crystalline, semi-crystalline, amorphous, or semi-amorphous state representing a resistance value, that value is retained until reset as that value represents a physical state of the material (e.g., crystalline or amorphous). Thus, phase change memory materials represent a significant improvement in non-volatile memory.
One characteristic common to solid state and phase change memory devices is significant power consumption particularly in setting or resetting memory elements. Power consumption is significant, particularly in portable devices that rely on power cells (e.g., batteries). It would be desirable to decrease the power consumption of a memory device.
REFERENCES:
Hwang, Y.N., Hong, J.S., Lee, S.H., Ahn, S.J., Jeong, G.T., Koh, G.H., Kim, H.J., Jeong, W.C., Lee, S.Y., Park, J.H., Ryoo, K.C.., Horii, H., Ha, Y.H., Yi, J.H., Cho, W.Y., Kim, Y.T., Lee, K.H., Joo, S.H., Park, S.O., Jeong, U.I., Jeong, H.S. and Kim, Kinam, “Completely CMOS-Compatible Phase-Change Nonvolatile RAM Using NMOS Cell Transistors,” presented at 2003 19thIEEE Non-Volatile Semiconductor Memory Workshop, Monterey, California, Feb. 26-20, 2003.
Ha, Y.H., Yi, J.H., Horii, H., Park, J.H., Joo, S.H., Park, S.O., Chung, U-In and Moon, J.T., “An Edge Contact Type Cell for Phase Change RAM Featuring Very Low Power Consumption,” presented at IEEE 2003 Symposium on VLSI Technology, Kyoto, Japan, Jun. 12-14, 2003.
Hwang, Y.N., Hong, J.S., Lee, S.H., Ahn, S.J., Jeong, G.T., Koh, G.H., Oh, J.H., Kim, H.J., Jeong, W.C., Lee, S.Y., Park, J.H., Ryoo, K.C., Horii, H., Ha, Y.H., Yi, J.H., Cho, W.Y., Kim, Y.T., Lee, K.H., Joo, S.H., Park, S.O., Chung, U.I., Jeong, H.S. and Kim, Kinam, “Full Integration and Reliability Evaluation of Phase-change RAM Based on 0.24 mm-CMOS Technologies,” presented at IEEE 2003 Symposium on VLSI Technology, Kyoto, Japan, Jun. 12-14, 2003.
Horii, H., Yi, J.H., Park, J.H., Ha, Y.H., Baek, I.G., Park, S.O., Hwang, Y.N., Lee, S.H., Kim, Y.T., Lee, K.H., Chung, U-In and Moon, J.T., “A Novel Cell Technology Using N-doped GeSbTe Films for Phase Change RAM,” presented at IEEE 2003 Symposium on VLSI Technology, Kyoto, Japan, Jun. 12-14, 2003.
Chiang Chien
Wicker Guy C.
Nelms David
Tran Mai-Huong
Trop Pruner & Hu P.C.
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