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Phase change memory materials, devices and methods

A phase change material, phase change storage technology, applied in static memory, read-only memory, information storage and other directions, can solve problems such as high energy consumption

Inactive Publication Date: 2009-01-14
UNIV OF SOUTHAMPTON
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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  • Phase change memory materials, devices and methods
  • Phase change memory materials, devices and methods
  • Phase change memory materials, devices and methods

Examples

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example 1

[0114] Example 1 - Operation of GLS Phase Alloys

[0115] In this example, we illustrate the electrical phase transition behavior of thin-film GLS alloys. The phase change alloy includes Ga, La and S, wherein the ratio of Ga to La to S (Ga:La:S) is selected to be about 1:3:6 to form the phase change alloy. More preferably, the electrical phase change alloy comprises Ga, La, S in the ratio of Gaw Lax Sy, where 5<w<10, 25<x<35, 50<y<70. More preferably, w+x+y=100%. More preferably, the ratio of Ga atoms to S atoms and La atoms to S atoms is chosen to be 2:3, and the ratio of 2Ga:3S to 2La:3S is chosen to be 1:3.

[0116] In one embodiment of the invention, the means for transferring are a first contact and a second contact. Each of the contacts abuts a roll of memory material. As used herein, a contact abuts a roll of memory material if at least a portion of the contact is in contact with the memory material.

[0117] Borosilicate microscope slides were used as substrates o...

example 2

[0121] Example 2-Electrical Phase Change Memory Cell Array

[0122] In this example, we illustrate the operation of our GLS phase change alloy as an electrical data storage element. We elucidate the electrical phase transition behavior of memory cell arrays fabricated according to a range of GLS alloy compositions. Phase change alloys include Ga, La and S, where Ga is selected and the ratio of La to S varies over a wide range. Here, the phase change alloy includes Ga, La, S in the ratio of Gaw Lax Sy, where 5<w<10, 25<x<35, 50<y<70, and w+x+y=100%.

[0123] Metal tracks were thermally evaporated onto a suitable substrate using an Edward type coating apparatus as shown in the previous examples. Since the melting point of chromium (1907° C.) is much higher than that of the above-mentioned GLS phase change alloy, chromium is used to make the track. Typically the tracks are 1mm wide, 200nm deep and 50nm long. Then, the phase-change alloy GLS was deposited on the surface electr...

example 3

[0130] Example 3 - GLS Alloy Optimization

[0131] To optimize Ga:La:S glass systems for phase transition applications, experimental studies were performed to analyze the crystallization kinetics of a series of glasses with variable Ga to La ratios. A smaller deviation from the eutectic composition results in a larger increase in crystallization time. With such a eutectic composition, conventional phase change materials can be crystallized in only 30 ns, but if only 10% deviate from this eutectic, the crystallization time increases by more than 1 μs. This illustrates the need to design phase change materials with such eutectic compositions.

[0132] Early studies on measuring glasses based on Ga:La:S eutectics had drawbacks due to the lack of phase-pure raw materials, especially phase-pure gallium sulfide. To avoid this problem, the method described in US 6,803,335 [79] was used to synthesize and test phase pure materials.

[0133] By incorporating equimolar amounts of pure...

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Abstract

A new class of phase change materials has been discovered based on compounds of: Ga; lanthanide; and chalcogenide. This includes compounds of Ga, La, and S (GLS) as well as related compounds in which there is substitution of S with O, Se and / or Te. Moreover, La can be substituted with other lanthanide series elements. It has been demonstrated that this class of materials exhibit low energy switching. For example, the GLS material can provide an optical recording medium with erasability 3-5 dB greater than the erasability of GeSbTe (GST) material which is the standard material for phase change memories.

Description

technical field [0001] The present invention relates generally to phase change memories, and in particular to materials useful for such memories. Background technique [0002] Phase change memory elements are programmable by inputting energy of one form or another. Most commonly, light or electrical energy is used. [0003] Phase change materials are materials that transition between a generally amorphous state and a generally crystalline state. As is known in the art, these materials are used in memories that use electrical energy, light energy, or other energy to transition the material between its different states. [0004] From the 1960s to the present, there are numerous patents related to inventions obtained by Ovshinsky and associates of Energy Conversion Device, Inc. [1-14]. There are also many other patents in this field [15-78]. [0005] Phase change memory materials can change between generally amorphous and generally crystalline locally ordered structural sta...

Claims

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Application Information

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IPC IPC(8): G11C16/02
Inventor D·W·赫瓦克R·J·库瑞M·K·A·梅拉加R·E·辛普森
Owner UNIV OF SOUTHAMPTON
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