KR20090047717A - Fabrication method of phase-change memory device - Google Patents

Abstract

A method of manufacturing a phase change memory device is provided.

In the phase change memory device according to the present invention, a phase change material layer, an upper electrode material layer, an antireflection film, and a hard mask are sequentially formed on a semiconductor substrate on which a lower structure is formed, and an antireflection film is formed by using an etching gas to neutralize electrons. It is formed through the step of etching and patterning the upper electrode material layer and the phase change material layer, it is possible to finely pattern the phase change material.

PRAM, phase change material, polymer

Description

Fabrication Method of Phase-Change Memory Device

The present invention relates to a phase change memory device, and more particularly, to a method of manufacturing a phase change memory device capable of accurately patterning a phase change material without error.

Phase-change random access memory (PRAM) records and reads information using phase-change characteristics in which chalcogenide alloys have high resistance in the amorphous state and low resistance in the crystalline state. Shipment is a memory element, which has the advantage of having a high operating speed and high integration compared to the flash memory.

In manufacturing a PRAM, a phase change material pattern and an upper electrode pattern should be formed on a semiconductor substrate on which lower structures such as lower electrodes and lower electrode contacts are formed. Currently, GST (GexSbyTez) is mainly used as a phase change material. Since GST is a very sensitive material, it is affected not only by damage during etching but also when removing photoresist.

To prevent this, an upper electrode material layer is formed on the GST, an anti-reflection film and a hard mask are formed, and then the anti-reflection film is etched by an ex-situ etching method using the hard mask as a barrier layer, followed by The electrode and phase change material are patterned.

During the ex-situ etching process, 10 to 20% over etching is performed using a chemical product based on CF ₄ / CHF ₃ / Ar / O ₂ , and at this time, a high boiling point is caused by sputtering or chemical reaction. TiFx-based polymers or Ti + ions are produced.

Accordingly, Ti or TiFx-based metal polymers are deposited as a result of the electron shadowing effect by electrons charged up on the sidewalls of the hard mask, and thus, subsequent etching processes are not precisely performed.

1 is a cross-sectional view illustrating a general method of manufacturing a phase change memory device.

As illustrated, a phase change material layer 20, an upper electrode material layer 30, an antireflection film 40, and a hard mask 50 are formed on the semiconductor substrate 10 on which the lower electrode and the like are formed. Then, the anti-reflection film 40 is etched using the hard mask 50 as a barrier.

Here, the etching process is carried out ex-situ using chemicals based on CF ₄ / CHF ₃ / Ar / O ₂ .

During the etching process, the metal polymer 60 is deposited on the side wall of the hard mask 50 by the chemical reaction of the etching gas.

2A and 2B are SEM images of a typical phase change memory device.

As shown in FIG. 2A, it can be seen that the metal polymer is attached to the sidewall of the hard mask 50.

In this state, when the upper electrode material layer 30 and the phase change material layer 20 under the anti-reflection film 40 are patterned, the metal polymer 60 acts as a barrier, so that the upper electrode pattern and the phase change material layer There is a problem in that the pattern cannot be formed accurately, resulting in a decrease in reliability such as malfunction of the device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and there is a technical problem to provide a method for manufacturing a phase change memory device in which a polymer does not adhere to a hard mask sidewall when a phase change material layer pattern is formed.

Another technical problem of the present invention is to provide a method of manufacturing a phase change memory device capable of accurately patterning a phase change material layer by using an etching gas capable of neutralizing electrons charged up in a hard mask when forming a phase change material pattern. To provide.

According to one or more exemplary embodiments, a phase change material layer, an upper electrode material layer, an antireflection film, and a hard mask are sequentially formed on a semiconductor substrate on which a lower structure is formed. Making; Etching the anti-reflection film by using an etching gas that neutralizes electrons; And patterning the upper electrode material layer and the phase change material layer.

According to the present invention, it is possible to finely pattern the phase change material by suppressing the generation of polymer during the etching process for forming the phase change material pattern.

Accordingly, there is an advantage that reliability and production yield are increased by preventing malfunction of the phase change memory device.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

3A and 3B are cross-sectional views illustrating a method of manufacturing a phase change memory device according to an embodiment of the present invention.

As shown in FIG. 3A, a phase change material layer 110 and an upper electrode material layer 120 are formed on a semiconductor substrate 100 on which a lower structure such as a lower electrode (not shown), a lower electrode contact (not shown), or the like is formed. The antireflection film 130 and the hard mask 140 are sequentially formed.

Then, the anti-reflection film 130 is etched by an etch-to-etch process using the hard mask 140 as a barrier using an etching gas for neutralizing electrons.

Here, the etching gas for neutralizing the electrons may use a hydrogen-containing gas, preferably a CHF ₃ / O ₂ / Ar base chemical gas.

When CHF ₃ / O ₂ / Ar base chemical gas is used as an etching gas, electrons charged-up on the sidewall of the hard mask 140 are neutralized by hydrogen gas to generate Ti or TiFx-based metal polymers. You can prevent it.

3B is a cross-sectional view of the phase change memory device after the etching process is completed, and the upper electrode pattern 120A and the phase change material pattern 110A are correctly formed using the hard mask 140 having no polymer attached to the sidewall as a barrier. Able to know.

4A and 4B are SEM images of a phase change memory device manufactured by the present invention.

First, FIG. 4A shows a cross-sectional view of a cross-section of a phase change memory device manufactured by the present invention. As compared with FIG. 2A, it can be seen that a polymer or the like is not attached to a sidewall.

Next, FIG. 4B is a plan view of the phase change memory device manufactured according to the present invention. As compared with FIG. 2B, it can be seen that the upper electrode pattern and the phase change material pattern are evenly patterned in a straight line.

As such, the present invention can prevent the polymer from adhering to the hard mask sidewalls during the phase change material patterning process, thereby improving the reliability of the subsequent etching process. In addition, it is possible to obtain a desired phase change material pattern only by over etching without unnecessary and just etching.

As such, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Since the present invention can accurately pattern a phase change material layer, it is advantageous for high integration of semiconductor devices.

Portable devices such as mobile phones, PDAs and mobile PCs require high density memory devices that operate at low power consumption. Since the phase change memory device of the present invention can finely pattern the phase change material layer, the integration degree of the device can be improved, and thus, the advantages thereof can be maximized when applied to a portable device.

1 is a cross-sectional view illustrating a method of manufacturing a general phase change memory device;

2A and 2B are SEM images of a typical phase change memory device,

3A and 3B are cross-sectional views illustrating a method of manufacturing a phase change memory device according to an embodiment of the present invention;

4A and 4B are SEM images of a phase change memory device manufactured by the present invention.

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

100 semiconductor substrate 110 phase change material layer

110A: phase change material pattern 120: upper electrode material layer

120A: upper electrode pattern 130: antireflection film

140: hard mask

Claims (3)

Sequentially forming a phase change material layer, an upper electrode material layer, an anti-reflection film, and a hard mask on the semiconductor substrate on which the lower structure is formed; Etching the anti-reflection film by using an etching gas that neutralizes electrons; And Patterning the upper electrode material layer and the phase change material layer; Phase change memory device manufacturing method comprising a. The method of claim 1, The etching gas is a CHF ₃ / O ₂ / Ar base chemical gas, characterized in that the phase change memory device manufacturing method. The method of claim 1, The etching gas is a phase change memory device, characterized in that the chemical gas containing hydrogen.

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