Active solid-state devices (e.g. – transistors – solid-state diode – Semiconductor is selenium or tellurium in elemental form
Reexamination Certificate
2002-04-08
2004-11-30
Elms, Richard (Department: 2824)
Active solid-state devices (e.g., transistors, solid-state diode
Semiconductor is selenium or tellurium in elemental form
C257S002000, C257S003000, C257S004000, C257S005000
Reexamination Certificate
active
06825489
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to microelectronic memory devices. More particularly, the invention relates to programmable microelectronic structures having an electrical property that can be variably programmed by manipulating an amount of energy supplied to the structure during a programming function.
BACKGROUND OF THE INVENTION
Memory devices are often used in electronic systems and computers to store information in the form of binary data. These memory devices may be characterized into various types, each type having associated with it various advantages and disadvantages.
For example, random access memory (“RAM”) which may be found in personal computers is typically volatile semiconductor memory; in other words, the stored data is lost if the power source is disconnected or removed. Dynamic RAM (“DRAM”) is particularly volatile in that it must be “refreshed” (i.e., recharged) every few microseconds in order to maintain the stored data. Static RAM (“SRAM”) will hold the data after one writing so long as the power source is maintained; once the power source is disconnected, however, the data is lost. Thus, in these volatile memory configurations, information is only retained so long as the power to the system is not turned off. In general, these RAM devices can take up significant chip area and therefore may be expensive to manufacture and consume relatively large amounts of energy for data storage. Accordingly, improved memory devices suitable for use in personal computers and the like are desirable.
Other storage devices such as magnetic storage devices (e.g., floppy disks, hard disks and magnetic tape) as well as other systems, such as optical disks, CD-RW and DVD-RW are non-volatile, have extremely high capacity, and can be rewritten many times. Unfortunately, these memory devices are physically large, are shock/vibration-sensitive, require expensive mechanical drives, and may consume relatively large amounts of power. These negative aspects make such memory devices non-ideal for low power portable applications such as lap-top and palm-top computers, personal digital assistants (“PDAs”), and the like.
Due, at least in part, to a rapidly growing numbers of compact, low-power portable computer systems and hand-held appliances in which stored information changes regularly, low energy read/write semiconductor memories have become increasingly desirable and widespread. Furthermore, because these portable systems often require data storage when the power is turned off, non-volatile storage device are desired for use in such systems.
One type of programmable semiconductor non-volatile memory device suitable for use in such systems is a programmable read-only memory (“PROM”) device. One type of PROM, a write-once read-many (“WORM”) device, uses an array of fusible links. Once programmed, the WORM device cannot be reprogrammed.
Other forms of PROM devices include erasable PROM (“EPROM”) and electrically erasable PROM (EEPROM) devices, which are alterable after an initial programming. EPROM devices generally require an erase step involving exposure to ultra violet light prior to programming the device. Thus, such devices are generally not well suited for use in portable electronic devices. EEPROM devices are generally easier to program, but suffer from other deficiencies. In particular, EEPROM devices are relatively complex, are relatively difficult to manufacture, and are relatively large. Furthermore, a circuit including EEPROM devices must withstand the high voltages necessary to program the device. Consequently, EEPROM cost per bit of memory capacity is extremely high compared with other means of data storage. Another disadvantage of EEPROM devices is that, although they can retain data without having the power source connected, they require relatively large amounts of power to program. This power drain can be considerable in a compact portable system powered by a battery.
Various hand-held appliances such as PDA, portable phones, and the like as well as other electronic systems may desirably include multiple forms of memory. For example, an appliance system may include nonvolatile memory such as PROM to store user-specific information, including system instructions and critical data such as unit codes, identification, and user-entered information and also include volatile memory such as SRAM and/or DRAM to store, for example, session-specific information such as web pages and downloaded content such as compressed audio and/or video information. The different forms of memory are typically formed on separate substrates because of different technologies and processing employed to form the various forms of memory. The multiple forms of memory are coupled together, e.g., through use of another substrate such as a printed circuit board, to integrated the various forms of memory with a digital processor.
Forming the various forms of memory on separate substrates may be undesirable for several reasons. For example, forming various types of memory on separate substrate may be relatively expensive to manufacture, may require relatively long transmission paths to communicate between the memory devices and any associated electronic device, and may take up a relatively large amount of room within a system. Accordingly, memory devices including both volatile and nonvolatile memory and methods of forming the memory devices are desired. Furthermore, this memory technology should meet the requirements of the new generation of portable and/or stationary computer devices by operating at a relatively low voltage while providing high speed memory with high storage density and a low manufacturing cost.
SUMMARY OF THE INVENTION
The present invention provides improved microelectronic memory devices, structures, and systems and methods of forming the same. More particularly, the invention provides memory structures that can be variably programmed depending on an amount of energy used to program the device. Such structures can replace both traditional nonvolatile and volatile forms of memory.
The ways in which the present invention addresses various drawbacks of now-known programmable devices are discussed in greater detail below. However, in general, the present invention provides a programmable device that is relatively easy and inexpensive to manufacture, which is relatively easy to program, and which be variably programmed.
In accordance with one exemplary embodiment of the present invention, a programmable structure includes an ion conductor and at least two electrodes. The structure is configured such that when a bias is applied across two electrodes, one or more electrical properties of the structure change. In accordance with one aspect of this embodiment, a resistance across the structure changes when a bias is applied across the electrodes. In accordance with other aspects of this embodiment, a capacitance or other electrical property of the structure changes upon application of a bias across the electrodes. In accordance with a further aspect of this embodiment, an amount of change in the programmable property is manipulated by altering (e.g., thermally or electrically) an amount of energy used to program the device. One or more of these electrical changes and/or the amount of change may suitably be detected. Thus, stored information may be retrieved from a circuit including the structure.
In accordance with another exemplary embodiment of the invention, a programmable structure includes an ion conductor, at least two electrodes, and a barrier interposed between at least a portion of one of the electrodes and the ion conductor. In accordance with one aspect of this embodiment, the barrier material includes a material configured to reduce diffusion of ions between the ion conductor and at least one electrode. The diffusion barrier may also serve to prevent undesired electrodeposit growth within a portion of the structure. In accordance with another aspect, the barrier material includes an insulating material. Inclusion of an insulating material increases the
Axon Technologies Corporation
Menz Douglas
Snell & Wilmer L.L.P.
LandOfFree
Microelectronic device, structure, and system, including a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microelectronic device, structure, and system, including a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microelectronic device, structure, and system, including a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3317222