KR20110072024A - Method for fabricating phase-change memory device - Google Patents

Abstract

PURPOSE: A method for manufacturing a phase change memory device is provided to improve a step coating property at a low temperature by repeating an insulation layer forming cycle of a multi-step. CONSTITUTION: A phase change layer pattern(107) is formed on a semiconductor substrate. A top electrode pattern(108) is formed on the phase change layer pattern. A capping layer(109) is formed by depositing an insulation layer which surrounds the phase change layer pattern and the top electrode pattern several times below a temperature to induce the phase change of the phase change layer pattern.

Description

Method for manufacturing phase change memory device {Method for Fabricating Phase-Change Memory Device}

The present invention relates to a method of manufacturing a phase change memory device, and more particularly, to a method of manufacturing a phase change memory device for forming a capping film of a phase change material.

In accordance with the demand for low power consumption of memory devices, next-generation memory devices that are non-volitile and do not need refresh are being studied. One of the next generation memory devices, phase-change random access memory (hereinafter referred to as 'PCRAM') is a phase change material such as GeSbTe, which is crystallized by local heat generation by electrical pulses. It is a device that stores binary information by using characteristics that change into (crystalline) and amorphous (amorphous) states.

That is, the phase change memory device may program data by changing resistance values of the phase change material layer according to a temperature and a heating time of heating the phase change material layer. The temperature characteristic of the phase change material layer is an important factor in determining the operation characteristics of the phase change memory device.

On the other hand, due to the characteristics of the phase change material, the phase change material layer is formed at a low temperature process of 400 ° C. or less, and the subsequent process also proceeds to a low temperature process without affecting the properties of the phase change material layer. Therefore, it is important to form a capping film that can protect the phase change material layer from heat generated in subsequent subsequent and other processes.

However, when forming the capping film, it is practically difficult to form the capping film so as to sufficiently surround the phase change material layer.

An object of the present invention is to provide a method for manufacturing a phase change memory device for forming a capping film having improved step coverage even in a low temperature process.

In order to achieve the technical object of the present invention, a method of manufacturing a phase change memory device according to an embodiment of the present invention is to form a phase change film pattern on a semiconductor substrate, the upper electrode pattern on the phase change film pattern Forming a capping film by repeatedly depositing an insulating film surrounding the phase change film pattern and the upper electrode pattern at a time below the temperature range at which the phase change of the phase change film pattern is induced. .

According to the method of manufacturing a phase change memory device according to an embodiment of the present invention, a multi-step insulating film forming cycle is formed when a capping film is formed to surround and protect the phase change film pattern and the upper electrode pattern. By repeating this, the step coverage can be improved even at a low temperature process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided to sufficiently convey the spirit of the present invention to those skilled in the art. Therefore, the present invention can be embodied in other forms without being limited to the embodiments described below. In the drawings, lengths, thicknesses, and the like of layers and regions may be exaggerated for convenience of description. Like numbers refer to like elements throughout the specification. In addition, where a layer or film is said to be on another layer or on another "on" it may be formed directly on the other film or on another layer, or a third layer or film may be interposed therebetween.

Hereinafter, a method of manufacturing a phase change memory device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. 1 to 4 are cross-sectional views sequentially illustrating a method of manufacturing a phase change memory device according to an embodiment of the present invention.

First, referring to FIG. 1, a high concentration n-type impurity region (not shown) is formed in the semiconductor substrate 101.

An interlayer insulating film 102 is formed over the semiconductor substrate 101 on which the high concentration n-type impurity region (not shown) is formed. The first interlayer insulating film 102 may be a high density plasma (HDP) film having dense film quality properties and including interlayer planarization properties.

The PN diode pattern 103 is formed in the first interlayer insulating layer 102. The PN diode pattern 130 includes a P-type material film 103a and an N-type material film 103b. In the case of a bonded word line, the PN diode pattern 103 may be formed by an SEG method, and in the case of a metal word line, the PN diode pattern 103 may be formed of a polysilicon film.

A conductive material, for example, a cobalt metal film 104, is formed on the interlayer insulating film 102 on which the PN diode pattern 103 is formed. The lower electrode pattern 106 is formed in the second interlayer insulating film 105 formed on the cobalt metal film 104. The lower electrode pattern 106 may be a TiN-based conductive layer.

The phase change material film is deposited on the resultant using a chalcogen compound, that is, a GeSbTe material, and then patterned to form a phase change film pattern 107. An upper electrode pattern 108 is formed on the phase change layer pattern 107.

Referring to FIG. 2, the first material layer 109a for the capping layer is formed on the resultant.

According to an embodiment of the present invention, when forming a capping film that surrounds and protects the phase change film pattern 107 and the upper electrode pattern 108 together, a multi-step insulating film formation cycle is repeated. It can be formed to a desired desired thickness.

In general, the oxidation of the interface between the lower electrode pattern 106 and the phase change film pattern 107 is prevented, and an external part of an element of some of the phase change materials of the phase change film pattern 107 such as Te, Sb, etc. A capping film surrounding the phase change film pattern 107 and the upper electrode pattern 108 is required to prevent diffusion of the furnace. Accordingly, the capping layer must be formed of a material that has sufficient durability against thermal volume change that may occur during a high temperature phase change process. In addition, when the capping film is formed, it is important to form the capping film within a temperature range that does not cause a phase change of the phase change film pattern 107. For example, if a capping film is to be formed using a nitride such as Si 3 N 4, and if a low pressure chemical vapor deposition (LPCVD) process is used, the LPCVD process uses a high temperature of 600 ° C. or higher, and thus, It is impossible to apply. In addition, when the capping layer is formed by using a plasma enhanced chemical vapor deposition (PECVD) process, the aspect ratio between the phase change layer pattern 107 and the upper electrode pattern 108 is high, thereby providing step coverage. ) Can be lowered. Furthermore, due to the nature of the nitride, it is easy to deposit on a flat surface, but difficult to conformally form a pattern with a predetermined thickness. Thus, in the subsequent wet etching process, the wet etch rate characteristics were not good and a part of the capping film could be partially lost. In other words, when forming the capping film, it was difficult to improve the step coverage in a temperature range not causing the phase change of the phase change film pattern 107.

However, according to one embodiment of the present invention, when the capping film is formed using the nitride material, the nitride material is repeatedly deposited a plurality of times to a predetermined thin thickness by using SiH 4, NH 3, and N 2 gas. After nitride deposition each time, post-treatment is performed. In this way, the deposition and post-treatment of the nitride material film may be applied in one cycle, thereby repeating the cycle to form a capping film having a desired target thickness.

More specifically, in a temperature range that does not cause phase shift of the phase change film pattern 107, such as a process temperature of about 300 to 350 ° C. and an RF power supply condition of 200 W, SiH 4 gas is injected at 70 sccm, and NH 3 gas is injected. By supplying 100 sccm and N2 gas in an amount of 2000 sccm, the first material film 109a for the capping film is formed to a thickness of about 50 kPa to 60 kPa. As described above, forming a relatively thin thickness at one time is more easily conformally formed along the profiles of the phase change film pattern 107 and the upper electrode pattern 108, thereby improving step coverage.

After the formation of the first material film 109a for the capping film, post-treatment is performed on the entire surface of the substrate resultant to densify the film quality using N2 gas. By performing this post-treatment, it is possible to enhance the physical properties of the deposited first material film 109a for the capping film and to suppress oxide penetration of the first material film 109a for the capping film by a subsequent process. At the same time, by performing post-treatment, the film quality of the first material film 109a for the capping film becomes dense.

This post treatment allows N2 gas to be supplied in an amount of 2000 sccm for approximately 5-7 seconds at 200 W of RF power supply conditions.

Referring to FIG. 3, a second material layer 109b for a capping layer is formed on the resultant.

That is, at a process temperature of about 300 to 350 ° C. and an RF power supply condition of 200 W, the SiH 4 gas is injected at 70 sccm, the NH 3 gas is supplied at 100 sccm, and the N 2 gas is supplied at an amount of 2000 sccm to form the first material film 109a for the capping film. To form a thickness of about 50 mm 3. After forming the second material layer 109b for the capping layer, the N2 gas is supplied to the front surface of the substrate in an amount of 2000 sccm for about 5 to 7 seconds under a 200 W RF power supply condition.

Subsequently, the processes of FIGS. 2 and 3 are repeated to complete the capping film 109 having the target thickness, as shown in FIG. 4.

That is, the cycle of the nitride material film deposition and the post-treatment may be repeated about 13 to 15 cycles so that the capping film 109 having a predetermined thickness, for example, 700 Å thick, is formed. However, the number of cycles is not limited, and of course, may vary depending on the thickness of the final target capping layer 109 and may also vary depending on the thickness of the nitride material layer deposited every cycle. However, according to an embodiment of the present invention, it is important to form the capping film 109 in a multi-step deposition process so that the step coverage may be improved even in a low temperature process.

In addition, as the concentration of the N 2 gas is increased, the thickness of the thin film formed every cycle may be controlled to be thinner.

On the other hand, it is illustrated that the post-treatment is performed after the nitride material film is deposited, but in some cases, before forming the nitride material film, the pre-treatment may be performed and the nitride material film may be formed. However, it may be more desirable to perform post-treatment after deposition of the nitride film to further reduce damage or impact of previous results.

As described above, in the method of forming a capping film according to an embodiment of the present invention, by repeatedly depositing a nitride material to a predetermined thin thickness using SiH 4, NH 3, and N 2 gas, the capping film 109 having a target thickness is formed. Can be formed.

In the above, embodiments of the present invention have been described with reference to the accompanying drawings, but those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. The described embodiments are to be understood in all respects as illustrative and not 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.

1 to 4 are cross-sectional views sequentially illustrating a method of forming a phase change memory device according to an embodiment of the present invention.

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

101: semiconductor substrate 102: first interlayer insulating film

103: diode pattern 104: cobalt metal film

105: second interlayer insulating film 106: lower electrode pattern

107: phase change film pattern 108: upper electrode pattern

109: capping film

Claims (6)

Forming a phase change film pattern on the semiconductor substrate; Forming an upper electrode pattern on the phase change layer pattern; And Forming a capping film by repeatedly depositing an insulating film surrounding the phase change film pattern and the upper electrode pattern a plurality of times below a temperature range where a phase change of the phase change film pattern is caused. Manufacturing method. The method of claim 1, Forming the capping film, A post-treatment is performed in one cycle after the insulating film is formed, and the cycle is repeated. The method of claim 2, And the insulating film forms a nitride film of a predetermined thickness using SiH 4, NH 3, and N 2 gas. The method of claim 3, And the insulating film is formed at a process temperature of about 300 to 350 ° C. which is less than a temperature range in which a phase change of the phase change film pattern is caused. The method of claim 2, The post-treatment, A method of manufacturing a phase change memory device for densifying the film quality of the insulating film using N2 gas. The method of claim 1, The phase change film pattern is a method of manufacturing a phase change memory device formed of a chalcogenide compound.

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