CN105428532A - Dy-Ge-Sb-Te and Dy-Sb-Te phase change memory material - Google Patents

Abstract

Dy-Ge-Sb-Te and Dy-Sb-Te phase-change storage materials belong to the field of microelectronics. The present invention proposes a technology and a film preparation method for improving the phase transition performance of Ge-Sb-Te and Sb-Te by doping the Ge-Sb-Te or Sb-Te phase transition material with Dy element, and its chemical structural formula is Dy _{100 - xyz} (G _x Sb _y Te _z ), where 0≤x, 80<x+y+z<100. The advantages of Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory thin film materials are that excellent performance can be obtained by doping very little Dy, with higher thermal stability and crystalline resistance, and amorphous The resistance difference between the crystalline state is obvious, and the data retention characteristics are better.

Description

Dy-Ge-Sb-Te and Dy-Sb-Te Phase Change Memory Materials

technical field

The invention relates to a technology for improving the performance of Ge-Sb-Te and Sb-Te phase change materials and a thin film preparation method thereof, in particular to Dy-Ge-Sb-Te and Dy-Sb-Te phase change for phase change memory A storage film material belongs to the field of microelectronics.

Background technique

The principle of phase change memory (PCRAM) is to use chalcogenide compounds as the storage medium, and use electric pulses, laser pulses, etc. to provide energy to convert the material between the crystalline state (low resistance) and the amorphous state (high resistance) to achieve information writing. Entering and erasing, the reading of information is achieved by measuring the size of the resistance and comparing its high resistance "1" or low resistance "0".

Ge-Sb-Te is a nucleation-dominated phase-change memory material. Its low crystallization temperature leads to poor thermal stability, which has always restricted its further development. It is particularly important to improve its thermal stability through doping. Sb-Te is a growth-dominated phase change memory material with fast phase change, but its thermal stability is poor and its data retention is poor. Doping can not only maintain the rapid phase change, but also improve its thermal stability.

Contents of the invention

The purpose of the present invention is mainly to provide a kind of Dy-Ge-Sb-Te and Dy-Sb-Te phase change storage film material used for phase change memory, to improve the thermal stability, amorphous state resistance of phase change material, reduce The RESET current and melting temperature of the material, etc.

In order to solve the above-mentioned technical problems, the present invention adopts following technical scheme to realize:

A Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory material used for phase-change memory is formed by doping Dy in Ge-Sb-Te (or Sb-Te) phase-change memory material, which The general chemical formula is Dy _100-xyz (Gex Sb _y Te _z ), where 0≤x<40, 0< _y <40, 40<z<80, 80<x+y+z<100. The lower right part of the element in the general chemical formula in the present invention represents the molar ratio.

The composition of Ge-Sb-Te and Sb-Te used for phase change memory materials is not limited, preferably, for example, the atomic ratio of Ge-Sb-Te is 1:2:4, 2:3:6, 3 :2:6 or 2:2:5, etc., the atomic ratio of Sb-Te can be 4:1, 2:1 or 2:3, etc.

Preferably, the Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory materials used for phase-change memory, the external drive energy to realize the reversible change of resistivity and optical refractive index reflectivity can be Electric pulses, laser pulses, electron beams and thermal actuation.

Preferably, the Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory materials used in the phase-change memory are a thin film material.

Preferably, the obtained Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory materials have a film thickness of 100-250 nm.

The Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory materials used in the phase-change memory have higher crystallization temperature and better data retention, and their thermal stability is greatly improved.

The Dy-Ge-Sb-Te and Dy-Sb-Te phase-change memory materials used for the phase-change memory increase the resistance of the amorphous state and the resistance of the crystalline state.

The preparation method of Dy-Ge-Sb-Te and Dy-Sb-Te phase change storage material for phase change memory according to the present invention comprises the following steps:

According to the ratio of Ge, _Sb and _Te in the general chemical formula _{Dy 100-xyz} ( _GexSbyTez ), using _{GexSbyTez (} or _SbyTez ) alloy target and _Dy target co-sputtering to obtain the described Dy-Ge-Sb-Te (or Dy-Sb-Te) phase change memory material.

Preferably, the co-sputtering conditions are as follows: during the co-sputtering process, Ar gas with a purity of _99.999 % or more is introduced, the _{GexSbyTez (} or _SbyTez ) alloy target _adopts a radio frequency power supply, and the Dy target Use DC power or RF power. Preferably, the RF power of the _{GexSbyTez (} or _SbyTez ) _alloy target is _25W , and the DC power of the Dy target is 15W.

Preferably, during co-sputtering, the Dy target power is turned on after the _{GexSbyTez (} or _SbyTez ) _alloy target _glows . But not limited to this, the _GexSbyTez (or _SbyTez ) alloy target can also be turned on after the Dy target _glows , or both _{powers can} be turned on at the same time.

Preferably, the co-sputtering time is 10-30 minutes.

Preferably, the sputtering equipment used in the present invention is a conventional sputtering device in the prior art.

Compared with the prior art, the present invention is beneficial in that: the thin film material has strong high temperature thermal stability and crystalline resistance, obvious resistance difference between amorphous state and crystalline state, and better data retention characteristics .

Description of drawings

FIG. 1 is a graph showing the relationship between sheet resistance and temperature variation of Dy-Ge-Sb-Te phase-change memory thin film materials with different Dy contents in the embodiment.

Fig. 2 is a graph showing the calculation results of activation energy and data retention of Dy-Ge-Sb-Te phase-change memory thin film materials with different Dy contents in the embodiment.

detailed description

The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the protection scope of the present invention.

Preparation of Dy-Ge-Sb-Te phase change memory thin film materials with different Dy contents:

The phase change material in this embodiment is obtained by co-sputtering with a Ge ₂ Sb ₂ Te ₅ alloy target and a Dy target. The co-sputtering conditions are as follows: during the co-sputtering process, Ar gas with a purity of more than 99.999% is introduced, the Ge ₂ Sb ₂ Te ₅ alloy target adopts radio frequency power supply, and the Dy target adopts direct current power supply. The power of the RF power supply is 25W, and the power of the DC power supply is 10-30W. After the Ge ₂ Sb ₂ Te ₅ alloy target glows, turn on the power of the Dy target. The co-sputtering time is 30 minutes, and the film thickness is about 150-200 nm.

The Dy-Ge-Sb-Te phase-change memory thin film materials with different Dy contents obtained in this embodiment were tested to obtain Figure 1 and Figure 2:

FIG. 1 is a graph showing the relationship between sheet resistance and temperature variation of Dy-Ge-Sb-Te phase-change memory thin film materials with different Dy contents in the embodiment. As shown in FIG. 1 , the resistivity test is carried out on the series of Dy-Ge-Sb-Te phase-change memory thin film materials of the present invention, and the temperature-resistivity relationship curve is obtained. In Figure 1, the components are Ge ₂ Sb ₂ Te ₅ , Dy _0.3 (Ge ₂ Sb ₂ Te ₅ ) _99.7 , Dy _1.1 (Ge ₂ Sb ₂ Te ₅ ) _98.9 , Dy _2.5 (Ge ₂ Sb ₂ Te ₅ ) _97.5 , Dy _4.14 (Ge ₂ Sb ₂ Te ₅ ) _95.86 and Dy _5.2 (Ge ₂ Sb ₂ Te ₅ ) _94.8 Dy-Ge-Sb-Te phase change memory thin film materials with different Dy contents, and their corresponding crystallization temperature They are 166°C, 172.2°C, 176.4°C, 180.1°C, 194.7°C and 202.5°C, respectively. It can be seen that below the crystallization temperature, the Dy-Ge-Sb-Te series phase change memory film material is in an amorphous state with a high resistance state, and above the crystallization temperature, the Dy-Ge-Sb-Te series phase change memory film The material is in a crystalline state where the resistance is a low resistance state. Here, after Dy doping, the crystallization temperature of Dy-Ge-Sb-Te series phase-change memory thin film materials is higher than that of Ge ₂ Sb ₂ Te ₅ , which is beneficial to the improvement of data retention. For the present invention, the crystallization temperature of the Dy-Ge-Sb-Te series phase change memory thin film material increases with the increase of Dy content, so the crystallization temperature can be changed by adjusting the Dy content.

Fig. 2 is a graph showing the calculation results of activation energy and data retention of Dy-Ge-Sb-Te phase-change memory thin film materials with different Dy contents in the embodiment. Retention is a crucial characteristic of phase change materials and one of the important parameters to measure the performance of phase change materials. The retention force is used to characterize the thermal stability of the amorphous state. When the test temperature point is higher than the crystallization temperature, the phase change material has crystallized during the heating process, so the retention time of the amorphous state cannot be tested, so the retention force The test temperature point must be below the crystallization temperature. The failure time here is defined as the time corresponding to the half of the initial resistance corresponding to the point where the sheet resistance has just risen to the test temperature. From Figure 1, different Dy contents correspond to the crystallization temperature of Dy-Ge-Sb-Te series phase-change memory thin film materials. We choose Dy _0.3 (Ge ₂ Sb ₂ Te ₅ ) _99.7 , Dy _1.1 (Ge ₂ Sb ₂ Te ₅ ) _98.9 , Dy _2.5 (Ge ₂ Sb ₂ Te ₅ ) _97.5 The three components are used to test the failure time, and calculate the temperature corresponding to the crystallization activation energy and retention time. As shown in Figure ₂ , the crystallization activation energy (E _a ) of Dy _0.3 (Ge _{2 Sb 2} Te ₅ ) _99.7 is _2.37eV , and the ₁₀ -year data retention temperature is 86°C _; The crystallization activation energy (E _a ) is 2.74eV, and the 10-year data retention temperature is 88℃; the crystallization activation energy (E _a ) of Dy _2.5 (Ge ₂ Sb ₂ Te ₅ ) _97.5 is 2.95eV, and the 10-year data retention temperature is 99 ℃. It can be concluded from Figure 2 that the activation energy of Dy-Ge-Sb-Te phase change memory thin film material is higher than that of Ge ₂ Sb ₂ Te ₅ (2.24eV), and the 10-year data retention temperature is higher than that of Ge ₂ Sb ₂ Te ₅ (85°C )higher. The increase of crystallization activation energy is beneficial to the thermal stability of the amorphous state.

Compared with the prior art, the present invention is beneficial in that: the thin film material can obtain excellent performance by doping very little Dy, has strong high temperature thermal stability and crystalline resistance, and the amorphous and crystalline Significant resistance difference between states, better data retention characteristics.

The description and application of the embodiments of the present invention are illustrative and are not intended to limit the scope of the present invention to the above-described embodiments.

Claims (10)

1. for a Dy-Ge-Sb-Te or Dy-Sb-Te phase-change storage material for phase transition storage, mix Dy and form in Ge-Sb-Te or Sb-Te phase-change storage material, its chemical general formula is Dy _100-x-y-z(Ge _xsb _yte _z), wherein 0≤x<40,0<y<40,40<z<80,80<x+y+z<100; In chemical general formula, the lower right corner part of element represents mol ratio.

2., as claimed in claim 1 for Dy-Ge-Sb-Te or the Dy-Sb-Te phase-change storage material of phase transition storage, it is characterized in that, the atomic ratio of Ge-Sb-Te is 1:2:4,2:3:6,3:2:6 or 2:2:5; The atomic ratio of Sb-Te is 4:1,2:1 or 2:3.

3. as claimed in claim 1 for Dy-Ge-Sb-Te and the Dy-Sb-Te phase-change storage material of phase transition storage, it is characterized in that, as compared to pure Ge-Sb-Te with Sb-Te, this phase-change material has higher crystallization temperature and better data retention, and its thermal stability improves.

4. as claimed in claim 1 for Dy-Ge-Sb-Te or the Dy-Sb-Te phase-change storage material of phase transition storage, it is characterized in that, described Dy-Ge-Sb-Te or Dy-Sb-Te phase-change storage material realizes the external drive energy of the reversible transition of resistivity and light refractive index reflectivity, is electric pulse, laser pulse, electron beam or thermal drivers effect.

5., as claimed in claim 1 for Dy-Ge-Sb-Te or the Dy-Sb-Te phase-change storage material of phase transition storage, it is characterized in that, described Dy-Ge-Sb-Te or Dy-Sb-Te phase-change storage material is a kind of thin-film material.

6. the preparation method of Dy-Ge-Sb-Te or the Dy-Sb-Te phase-change storage material for phase transition storage as described in as arbitrary in claim 1-5, comprises the steps: according to chemical general formula Dy _100-x-y-z(Ge _xsb _yte _z) in Ge, Sb and Te proportioning adopt Ge _xsb _yte _zalloys target and Dy target co-sputtering obtain described Dy-Ge-Sb-Te phase-change storage material;

Or according to chemical general formula Dy _100-x-y-z(Ge _xsb _yte _z) in Sb and Te proportioning adopt Sb _yte _zalloys target and Dy target co-sputtering obtain Dy-Sb-Te phase-change storage material.

7. preparation method as claimed in claim 6, it is characterized in that, described cosputtering condition is: in cosputtering process, pass into the Ar gas that purity is more than 99.999%, Ge _xsb _yte _zor Sb _yte _zalloys target adopts radio-frequency power supply, and Dy target adopts DC power supply or radio-frequency power supply.

8. preparation method as claimed in claim 6, is characterized in that, during cosputtering, and described Ge _xsb _yte _zafter alloys target build-up of luminance, then open Dy target power supply; Or open Ge again after Dy target build-up of luminance _xsb _yte _zalloys target, or both power supplys are opened simultaneously;

During cosputtering, Sb _yte _zafter alloys target build-up of luminance, then open Dy target power supply; Or open Sb again after Dy target build-up of luminance _yte _zalloys target, or both power supplys are opened simultaneously.

9. preparation method as claimed in claim 6, it is characterized in that, described radio-frequency power supply power is 15-100W, and described DC power supply power is 15-80W, and the described cosputtering time is 5-50 minute.

10. preparation method as claimed in claim 6, it is characterized in that, Dy-Ge-Sb-Te or the Dy-Sb-Te phase-change storage material obtained is phase change film material, and its film thickness is 10-300nm.