High Capacity Low Cost Multi-State Magnetic Memory

Abstract

One embodiment of the present invention includes multi-state current-switching magnetic memory element including a stack of two or more magnetic tunneling junctions (MTJs), each MTJ having a free layer and being separated from other MTJs in the stack by a seeding layer formed upon an isolation layer, the stack for storing more than one bit of information, wherein different levels of current applied to the memory element causes switching to different states.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. patent application Ser. No. 11 / 678,515, entitled “A High Capacity Low Cost Multi-State Magnetic Memory,” filed Feb. 23, 2007, which was a continuation-in-part of U.S. patent application Ser. No. 11 / 674,124, entitled “Non-Uniform Switching Based on Non-Volatile Magnetic Base Memory,” filed Feb. 12, 2007, and is a continuation-in-part of U.S. patent application Ser. No. 11 / 860,467, entitled, “A Low Cost Multi-State Magnetic Memory”, filed Sep. 24, 2007, which is a continuation-in-part of U.S. patent application Ser. No. 11 / 678,515, entitled “A High Capacity Low Cost Multi-State Magnetic Memory,” filed Feb. 23, 2007, the disclosures of which are incorporated herein by reference, as though set forth in full.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates generally to non-volatile magnetic memory and particular to multi-state magnetic memory.[0004]...

AI Technical Summary

Benefits of technology

[0016]Briefly, an embodiment of the present invention includes multi-state current-switching magnetic memory element including a stack of two or more magnetic tunneling junctions (MTJs), each MTJ having a free layer and being separated f

Problems solved by technology

Though widely used and commonly accepted, such media suffer from a variety of deficiencies, such as access latency, higher power dissipation, large physical size and inability to withstand any physical shock.

Other dominant storage devices are dynamic random access memory (DRAM) and static RAM (SRAM), which are volatile and very costly but have fast random read/write access time.

Although NAND-based Flash memory is more costly than HDD's, it has replaced magnetic hard drives in many applications such as digital cameras, MP3-players, cell phones, and hand held multimedia devices due, at least in part, to its characteristic of being able to retain data even when power is disconnected.

However, as memory dimension requirements are dictating decreased sizes, scalability is becoming an issue because the designs of NAND-based Flash memory and DRAM memory are becoming difficult to scale with smaller dimensions.

For example, NAND-based Flash memory has issues related to capacitive coupling, few electrons/bit, poor error-rate performance and reduced reliability due to decreased read-write endurance.

It is believed that NAND Flash, especially multi-bit designs thereof, would be extremely difficult to scale below 45 nanometers.

Likewise, DRAM

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