KR20090052660A - Phase change memory device and method for manufacturing the same - Google Patents

Abstract

The present invention is simple in structure, it is possible to increase the contact area with the upper electrode to improve the adhesion failure, increase the area where the phase change occurs to increase the sensitivity change sensitivity according to the phase change Discuss the technology.

PRAM, Phase Change Resistor, Sb2Te2Se, Bad Adhesion, Deposition, CMP

Description

Phase change memory device and method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase change memory device and a method of forming the same. More particularly, the present invention relates to a phase change memory device, and to a method of forming the phase change memory device. The present invention relates to a phase change memory device capable of increasing resistance change sensitivity due to a phase change and a method of forming the same.

Generally, a memory device is divided into a non-volatile memory device in which stored data remains in a state in which a power supply is cut off, and a volatile memory device in which data is lost when a power supply is cut off.

With the spread of portable devices, the acceptance of nonvolatile memory devices is increasing rapidly. Here, a flash memory, a ROM, a ferroelectric memory, an MRAM, a nanoRAM, a polymer memory, a phase change memory, and the like have been developed in a nonvolatile memory device.

In particular, Phase Chang Random Access Memory (PRAM), also called OUM (Ovonic Unified Memory), is considered as the next-generation memory device because of its similar operating speed to DRAM, low operating voltage and power consumption, and non-volatile characteristics. I am getting it.

Phase change memory devices are implemented with phase change materials such as chalcogenide alloys that can be maintained in one of two states by heating and cooling. Here, the phase change material is generally implemented as a GST alloy including germanium (Ge), antimony (Sb), and tellurium (Te).

A phase change material is a material having reversible phase change characteristics between crystalline and amorphous states, and when an electric pulse is applied to the phase change material, the phase change material is heated. By applying a pulse for a short time to heat above the melting point (melting point) of the phase change material, and subsequently quenching (quenching) the phase change material is in an amorphous state, and a low current pulse is applied for a long time The change material is crystalline through an annealing process.

In addition, the phase change material has a high resistivity when amorphous, and a low resistivity when crystalline. Therefore, the phase change memory device stores data using the specific resistance change of the phase change state.

On the other hand, in a typical phase change memory device, a single phase change resistor implemented with one field effect transistor (FET) and one phase change material implements a unit memory cell. The configuration of the unit memory cell is just one example and is not limited thereto. That is, one diode, one phase change resistor, or one bipolar transistor and one phase change resistor may implement a unit memory cell.

Here, the phase change material is formed by using a thin film deposition equipment (sputter or evaporator), the phase change occurs quickly to store the data, and maintains the contact characteristics with the heater material (non-destructive characteristics for the phase change) It is difficult to find a phase change material.

In addition, when the phase change material is connected to the bottom electrode and the top electrode, there is a problem in that film lifting and film stress occur due to poor adhesion.

The present invention is simple in structure, it is possible to increase the contact area with the upper electrode to improve the adhesion failure, increase the area where the phase change occurs to increase the sensitivity change sensitivity according to the phase change An object of the present invention is to provide a phase change memory device and a method of forming the same.

Phase change memory device according to the present invention

A lower electrode connected to an access transistor selected by a word line;

A phase change memory layer formed of a phase change material and storing data;

An insulating layer formed on the lower electrode and including a lower electrode contact plug formed of the phase change material to electrically connect the phase change memory layer to the lower electrode; And

And an upper electrode formed on the phase change memory layer and connected to the bit line.

In addition, the phase change material is characterized in that the SbTeSe-based material.

On the other hand, the phase change memory device according to another embodiment of the present invention

A lower electrode connected to an access transistor selected by a word line;

A phase change memory layer formed of a phase change material and storing data;

An insulating layer formed on the lower electrode and including a lower electrode contact plug electrically connecting the phase change memory layer to the lower electrode; And

An upper electrode formed on the phase change memory layer and connected to a bit line;

The phase change memory layer may be formed of the phase change material and include a wineglass-shaped upper electrode contact plug having a larger upper area than a lower area contacting the lower electrode contact plug.

In addition, the phase change material is characterized in that the SbTeSe-based material.

Meanwhile, the method of forming a phase change memory device according to the present invention

Forming a lower electrode on the semiconductor substrate on which the lower structure is implemented;

Forming an insulating film on the semiconductor substrate including the lower electrode;

Selectively etching the insulating layer to form a lower electrode contact hole exposing the lower electrode;

A first deposition step of depositing and filling a phase change material only in a bottom portion of the lower electrode contact hole;

Performing a first planarization process on the phase change material until the insulating film is exposed;

Performing an etch back process on the insulating film;

Forming a lower electrode contact plug by performing a second planarization process on the phase change material formed in the lower electrode contact hole having a step formed through the etch back process;

A second deposition step of forming a phase change memory layer by depositing the phase change material on the insulating layer including the lower electrode contact plug; And

And forming an upper electrode on the phase change memory layer.

The method may further include forming spacers on sidewalls of the lower electrode contact holes.

The spacer may include a first spacer formed on an entire surface of a sidewall of the lower electrode contact hole; And

A second spacer formed only on a lower surface of the first spacer,

The first spacer is formed of a silicon nitride oxide (SiON),

The second spacer is formed of a silicon nitride film (SiN),

Forming a sacrificial oxide film on the insulating film;

The insulating film is formed of silicon nitride oxide (SiON),

The sacrificial oxide film is formed of a silicon oxide film (SiO 2),

The first planarization process is performed until the sacrificial oxide film is exposed,

The sacrificial oxide film is removed in the step of performing the etch back process,

Forming a barrier metal on the insulating layer including the lower electrode contact hole;

The barrier metal is formed of a titanium nitride film (TiN).

The present invention is simple in structure, it is possible to increase the contact area with the upper electrode to improve the adhesion failure, increase the area where the phase change occurs to increase the sensitivity change sensitivity according to the phase change It has an effect.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the spirit of the present invention is thoroughly and completely disclosed, and the spirit of the present invention to those skilled in the art will be fully delivered. Also, like reference numerals denote like elements throughout the specification.

1 is a cross-sectional view illustrating a phase change resistance of a phase change memory device according to the present invention.

The phase change resistor may include a lower electrode 12 connected to an access transistor selected by a word line, an upper electrode 14 connected to a bit line, and a phase change memory layer configured to store data by being formed of a phase change material. 16 and a lower electrode contact plug 18 electrically connecting the lower electrode 12 and the phase change memory layer 16. Here, the phase change memory layer 16 is implemented with a phase change material (Sb 2 Te 2 Se) that is a three-phase compound. In addition, the lower electrode contact plug 18, which electrically connects the phase change memory layer 16 and the lower electrode 12, is formed of a phase change material to increase an area in which phase change occurs, thereby increasing the resistance change resistance according to the phase change. Can be increased.

[Table 1] shows the binding energy of the phase change material (Sb2Te2Se) thin film, and [Table 2] shows the mechanical properties.

Ta (K) E (x) N / m (10 ²¹ cm 3) Eg (eV) Eg2 (eV) 290 20.899 1.681 1.039 323 22.840 1.915 1.040 373 35.612 3.209 0.878 423 86.723 8.270 0.794 1.031 473 78.045 7.617 0.753 0.95

Thermal Conductivity (W / cmK) 4.63E-3 (hcp) Heat Capacity (J / cm 3K) 1.25 Density (g / cm 3) 6.20 (fcc) Linear Thermal Expansion Coeffici ℃ ent (K ^-1 ) [300K-900K] 23.5 ppm

As described above, the phase change memory device according to the present invention includes a phase change resistance, and the phase change resistance includes a phase change memory layer formed of a three-component phase change material (Sb2Te2Se) in which data is stored. Here, the three-component phase change material (Sb2Te2Se) is capable of stable operation at a temperature of 130 ° C. for more than 10 years, has almost no limit on the number of writes and erases, and has a sufficiently low voltage for data programming. As a result, the resistance characteristic with current is stable over a wide temperature range.

2 is a crystallographic transmission electron microscope (TEM) photograph of a phase change material (Sb2Te2Se) thin film of phase change resistance according to the present invention. Here, (a) is a photograph showing a crystalline state after depositing a phase change material thin film, (b) is an amorphous state after rapidly cooling to 100 ℃ after heating to 623 ℃ The photograph is shown.

3A to 3F are cross-sectional views illustrating a method of forming a phase change resistor in a phase change memory device according to the present invention. Although a two-step deposition and a two-step planarization process are described as an example here, the number of deposition and planarization processes is not limited thereto.

Referring to FIG. 3A, a lower electrode 12 is formed on a semiconductor substrate having a lower structure, and an insulating film 20 is formed on the lower electrode 12, but a silicon nitride oxide (SiON) 21 and a sacrificial oxide film are formed on the lower electrode 12. Phosphorus silicon oxide (SiO 2) 22 is sequentially deposited, and the insulating layer 20 is selectively etched to form a lower electrode contact hole for exposing the lower electrode 12.

The spacers 24 are formed on sidewalls of the lower electrode contact holes, but are formed in a stacked structure of silicon nitride oxide (SiON) 25 and silicon nitride layer (SiN) 26. Here, the silicon nitride oxide film 26 of the spacer 24 is formed on the entire lower electrode contact hole sidewalls, and the silicon nitride film 25 is formed only below the lower electrode contact hole sidewalls. Therefore, the lower electrode contact hole is formed in the shape of a wineglass having a larger size than the lower portion.

Meanwhile, the barrier metal 28 is formed on the insulating film 20 including the spacer 24, but is formed of a titanium nitride film (TiN) 29.

The phase change material 30 filling the lower electrode contact hole on the barrier metal 28 is gradually increased to 30K to 748K using a method such as sputtering and evaporating, and an ingot. Furnace deposition is carried out. At this time, the phase change material 30 fills all of the lower portions of the lower electrode contact holes, but the phase change material 30 is deposited only on the sidewalls of the phase change material 30 to prevent adhesion failure.

Referring to FIG. 3B, the first planarization process may be performed by chemical mechanical polishing (CMP) or the like until the silicon oxide layer 22 is exposed to the phase change material 30.

Referring to FIG. 3C, the silicon oxide film 22 is removed by performing etch back on the exposed silicon oxide film 22.

Referring to FIG. 3D, a phase change material 30 is performed by performing a second planarization process using a CMP or the like to remove a step caused by the phase change material 30 and the spacer 20 generated while the silicon oxide film 22 is removed. Lower electrode contact plugs 18 are formed.

Referring to FIG. 3E, the phase change memory layer 16 is formed on the silicon nitride oxide film 20 including the lower electrode contact plug 18.

Referring to FIG. 3F, an upper electrode 14 is formed on the phase change memory layer 16 to complete a phase change resistance.

Figure 4 is a graph showing the resistance value with respect to the current of the phase change resistance according to the present invention.

5 is a cross-sectional view illustrating a phase change resistance of a phase change memory device according to another exemplary embodiment of the present invention.

The phase change resistor includes a lower electrode 32 connected to an access transistor selected by a word line, an upper electrode 34 connected to a bit line, and a phase in which data is stored as a phase change material. The lower memory contact plug 38 electrically connects the change memory layer 36 and the lower electrode 32 and the phase change memory layer 36. Here, the phase change memory layer 36 is formed of a phase change material (Sb2Te2Se), which is a three-phase compound, and has a wineglass-shaped upper electrode contact plug 40 having a larger upper area than a contact surface with the lower electrode contact plug 38. Include.

Therefore, the phase change resistance according to the present invention is simple in structure, increases the contact area with the upper electrode 34 to improve the adhesion defects, and increases the area where the phase change occurs to the phase change. It is possible to increase the sensitivity change resistance accordingly.

In addition, a preferred embodiment of the present invention is for the purpose of illustration, those skilled in the art will be able to various modifications, changes, substitutions and additions through the spirit and scope of the appended claims, such modifications and changes are the following claims It should be seen as belonging to a range.

1 is a cross-sectional view illustrating a phase change resistance of a phase change memory device (PRAM) according to the present invention.

2 is a crystallographic TEM photograph of a phase change material (Sb2Te2Se) thin film of phase change resistance according to the present invention.

3A to 3F are cross-sectional views illustrating a method of forming a phase change resistor in a phase change memory device (PRAM) according to the present invention.

Figure 4 is a graph showing the resistance value with respect to the current of the phase change resistance according to the present invention.

5 is a cross-sectional view illustrating a phase change resistance of a PRAM according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

12, 32: lower electrode 14, 34: upper electrode

16, 36: phase change memory layers 18, 38: lower electrode contact plugs

20: insulating film 21: silicon nitride oxide film (SiON)

22: silicon oxide film (SiO2) 24: spacer

25: silicon nitride film (SiN) 26: silicon nitride film

28: barrier metal (TiN) 30: phase change material (Sb2Te2Se)

40: upper electrode contact plug

Claims (16)

A lower electrode connected to an access transistor selected by a word line; A phase change memory layer formed of a phase change material and storing data; An insulating layer formed on the lower electrode and including a lower electrode contact plug formed of the phase change material to electrically connect the phase change memory layer to the lower electrode; And And an upper electrode formed on the phase change memory layer and connected to a bit line. The method of claim 1, And the phase change material is a SbTeSe-based material. A lower electrode connected to an access transistor selected by a word line; A phase change memory layer formed of a phase change material and storing data; An insulating layer formed on the lower electrode and including a lower electrode contact plug electrically connecting the phase change memory layer to the lower electrode; And An upper electrode formed on the phase change memory layer and connected to a bit line; And the phase change memory layer comprises a wineglass-shaped upper electrode contact plug formed of the phase change material and having a larger upper area than a lower area contacting the lower electrode contact plug. The method of claim 3, wherein And the phase change material is a SbTeSe-based material. Forming a lower electrode on the semiconductor substrate on which the lower structure is implemented; Forming an insulating film on the semiconductor substrate including the lower electrode; Selectively etching the insulating layer to form a lower electrode contact hole exposing the lower electrode; A first deposition step of depositing and filling a phase change material only in a bottom portion of the lower electrode contact hole; Performing a first planarization process on the phase change material until the insulating film is exposed; Performing an etch back process on the insulating film; Forming a lower electrode contact plug by performing a second planarization process on the phase change material formed in the lower electrode contact hole having a step formed through the etch back process; A second deposition step of forming a phase change memory layer by depositing the phase change material on the insulating layer including the lower electrode contact plug; And And forming an upper electrode on the phase change memory layer. The method of claim 5, wherein And forming a spacer on sidewalls of the lower electrode contact hole. The method of claim 6, The spacer may include a first spacer formed on an entire surface of a sidewall of the lower electrode contact hole; And And a second spacer formed only on the bottom surface of the first spacer. The method of claim 7, wherein The first spacer is formed of a silicon nitride oxide (SiON) method of forming a phase change memory device, characterized in that. The method of claim 8, And the second spacer is formed of a silicon nitride film (SiN). The method of claim 5, wherein And forming a sacrificial oxide film over the insulating film. The method of claim 10, The insulating film is a silicon nitride oxide (SiON) is formed, the method of forming a phase change memory device. The method of claim 11, And the sacrificial oxide layer is formed of a silicon oxide layer (SiO 2). The method of claim 10, And the first planarization process is performed until the sacrificial oxide film is exposed. The method of claim 10, And removing the sacrificial oxide layer in the step of performing the etch back process. The method of claim 5, wherein And forming a barrier metal on the insulating layer including the lower electrode contact hole. The method of claim 15, The barrier metal may be formed of a titanium nitride layer (TiN).

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