KR101159704B1 - Non-volatile programmable switch device including phase change layer and fabricating method thereof - Google Patents

Abstract

PURPOSE: A non-volatile programmable switch element and a manufacturing method thereof are provided to easily transfer an electric signal between logic blocks by forming phase-change in the inner side of a contact hole. CONSTITUTION: A metal layer(3) comprises a first terminal(1) and a second terminal(2). A conductive layer(4) is formed at the upper side of the metal layer. A contact hole(8) exposes a part of the upper side of the metal layer. The contact hole is filled with a phase-change layer(5). An insulating layer covers the conductive layer. The phase-change layer comprises a third terminal(6) and a fourth terminal(7). The first terminal and the second terminal are a programming terminal. The third terminal and the fourth terminal are a signal transfer terminal. The programming terminal and the signal transfer terminal are crossed in a contact hole area.

Description

Non-volatile programmable switch device including a phase change layer and a method of manufacturing the same {Non-volatile programmable switch device including phase change layer and fabricating method

The present invention relates to a nonvolatile programmable switch device including a phase change layer and a method of manufacturing the same. In particular, the present invention relates to a nonvolatile programmable switch device including a phase change material having a characteristic of changing a crystal state and a corresponding electrical resistance by an electric pulse input. The present invention relates to a programmable switch element and a method of manufacturing the same.

After circuit fabrication, there is a great demand for a programmable logic device (PLD) that can reconfigure some functions of the circuit to meet various user requirements. Programmable switch is located inside the PLD and controls the connection of logic blocks and interconnect wires or the connection of two different wires according to the user's programming. Do it.

Current commonly used components of programmable switches are SRAM, Flash memory, and anti-fuse.

SRAM acts as a switch by controlling a gate node connected to a pass transistor, which is the most widely used technology in PLDs because it is manufactured by a fast and well-established CMOS process with fast erase and write speeds. On the other hand, volatility, an inherent characteristic of SRAM, is a serious technical disadvantage in applying SRAM to a PLD. Driving an SRAM requires a separate external memory that retains the information needed to drive it even when the power is off, which increases manufacturing costs and is very vulnerable to information protection.

Two types of programmable switches can be configured using two floating gate flash memory transistors that share a floating gate and a control gate. Unlike SRAMs, such flash memories are nonvolatile, which retains information even in the absence of power. Flash memory does not require external memory and can be configured with only a small number of transistor cells, so there is an advantage of greater integration than SRAM.

Antifuse is a technology that utilizes the phenomenon of low electrical resistance due to the formation of a conductive single crystal structure in a very thin oxide film when high voltage is applied, and is the most advantageous programmable switch device in terms of cost. The reason is that it is possible to manufacture by CMOS technology, and its size is small and the degree of integration is high.

However, the limitation of programming is limited to one time, and there is a limit to maximizing the performance of PLD. As an alternative to the switch technology, a switch technology using a phase change material is drawing attention. Since the phase change material is nonvolatile, which maintains a high resistance to low resistance ratio without a power supply even at a nanometer size, the integration of the switch can be greatly increased by using nano scaling of the phase change material.

In addition, the phase change material has a very excellent resistance to high energy particle impact. As a result, an information change error due to the impact of high-energy particles generated in an SRAM and a flash-based switch device based on a MOS transistor including a gate oxide film does not occur in the switch device including a phase change material.

Until now, a nonvolatile programmable switch device including a phase change material having a vertical structure and a horizontal structure has been proposed.

1 is a plan view of a horizontal switch element using a conventional technique, Figure 2 is a cross-sectional view of a vertical switch element using a conventional technique.

The horizontal switch element of FIG. 1 includes a single phase change layer in which the first terminal 10, the second terminal 11, the third terminal 12, and the fourth terminal 13 are all the same. When the reset programming is performed through the second terminal 11 and the fourth terminal 13, an amorphous phase 14 is formed at the center thereof, thereby preventing transmission of an electrical signal through the first terminal 10 and the third terminal 12. do.

2 includes a first terminal 20, a second terminal 21, a third terminal 22, a fourth terminal 23, and a phase change layer 24. 21) and reset programming through the fourth terminal 23, an amorphous phase 25 is formed in the center of the phase change layer 24 to transmit electrical signals through the first terminal 20 and the third terminal 22. Is blocked.

Meanwhile, in the vertical and horizontal switch devices using the conventional techniques of FIGS. 1 and 2, when the set programming is performed through the second terminal and the fourth terminal, the crystalline channel having a small electric resistance in only a part of the region rather than the entire amorphous phase ( A partial set in which the 15 of FIG. 1 and the 26 of FIG. 2 are formed frequently occurs. This phenomenon is caused by the local current flow inside the phase change material, which is closely related to the size and shape of the parasitic capacitance component connected to the phase change material (D. Ielmini et al., IEEE ELECTRON DEVICE LETTERS, VOL. 26, NO. 11, (2005) 799., AL Lacaita et al., IEDM Tech. Dig., (2004) 911.).

When a partial set occurs, an amorphous phase with a very high electrical resistance still exists on a path through which the electrical signal is transmitted, and thus, transmission of the electrical signal through the first terminal and the third terminal is impossible. That is, the area between the two signal transmission terminals is in an open state. To solve this problem, a very large set programming current must be applied to change the entire amorphous phase into a crystalline phase.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the shortcomings of nonvolatile programmable switch devices having a vertical and horizontal structure including a phase change layer, which is a conventional technology, to easily transfer electrical signals between logic blocks after programming. A nonvolatile programmable switch device having a function and a method of manufacturing the same are provided.

In order to achieve the above object, a nonvolatile programmable switch device according to an embodiment of the present invention is a first terminal, a second terminal, a metal layer connected to the first terminal and the second terminal, a conductive layer, a phase change layer And a third terminal and a fourth terminal connected to the phase change layer. A portion of the phase change layer is located inside a contact hole formed on the conductive layer, and the phase change is limited to the inside of the contact hole by programming through the first terminal and the third terminal. When the crystal phase with low electrical resistance is formed by set programming, the switch element is turned on to transmit an electrical signal through the second terminal and the fourth terminal, and conversely, when the amorphous phase with high electrical resistance is formed by reset programming, the switch The device is turned off to block transmission of electrical signals through the second and fourth terminals.

According to another embodiment of the present invention, a nonvolatile programmable switch device includes a first terminal, a second terminal, a metal layer connected to the first terminal and a second terminal, a first conductive layer, a phase change layer, and a second conduction. Layer and a third terminal and a fourth terminal connected to the second conductive layer. The phase change layer is formed between the first conductive layer and the second conductive layer by solid phase alloying of the materials constituting the first conductive layer and the second conductive layer.

In addition, to achieve the above object, a method of manufacturing a nonvolatile programmable switch device according to the present invention includes the steps of forming a metal layer having a first terminal and a second terminal, forming a conductive layer formed on the metal layer, Forming an insulating layer covering the conductive layer to form a contact hole exposing a portion of the upper portion of the conductive layer; and filling the contact hole and forming a phase change layer having a third terminal and a fourth terminal. Include.

In addition, in order to achieve the above object, a method of manufacturing a nonvolatile programmable switch device according to the present invention may include forming a metal layer having a first terminal and a second terminal, and forming a first conductive layer formed on the metal layer. Forming an insulating layer covering the first conductive layer to form a contact hole exposing a portion of an upper portion of the conductive layer, filling the contact hole, and a second conductive layer having a third terminal and a fourth terminal Forming a phase change layer between the first conductive layer and the second conductive layer by solid phase alloying of the material constituting the first conductive layer and the material constituting the second conductive layer. .

As described above, the nonvolatile programmable device according to the present invention uses a structure in which a programming terminal and a signal transmission terminal cross each other in a contact hole region in which a part of a phase change layer is located. The effect of easily transmitting an electrical signal is obtained.

In addition, since the nonvolatile programmable device of the present invention uses a phase change material, the operation speed is fast, nonvolatile, and the repetitive write operation is excellent.

1 is a plan view of a nonvolatile programmable switch device including a phase change layer of a horizontal structure according to the prior art.
2 is a cross-sectional view of a nonvolatile programmable switch device including a phase change layer of a vertical structure according to the prior art.
3 is a plan view of a nonvolatile programmable switch device including a phase change layer according to an embodiment of the present invention.
4A to 4D are diagrams for describing a nonvolatile programmable switch device including a phase change layer and a method of manufacturing the same according to the present invention.
5 is a view for explaining the operation of the nonvolatile programmable switch device including a phase change layer according to the present invention.
6 is a cross-sectional view of a nonvolatile programmable switch device including a phase change layer according to another exemplary embodiment of the present invention.

These and other objects and novel features of the present invention will become more apparent from the description of the present specification and the accompanying drawings.

First, the concept of the present invention will be described.

Some of the materials containing chalcogenide (chalcogenide) and chalcogenide (S, Se, Te) and antimony (Sb) exhibit switching behavior in which the electrical resistance changes with voltage or current input. The material having the above characteristics is commonly referred to as a phase change material because the electric resistance value corresponding to each phase is different. In other words, the phase is reversibly changed according to the appropriate voltage or current input, and thus the electrical resistance is also reversibly changed. Since the electric resistance value varies within a very large range, this phase change material property can be applied as an information storage device. The reversible phase change process is divided into the following set and reset processes. The process of changing from a high-resistance amorphous phase to a low-resistance crystalline phase is called three, and the process of changing from a crystalline phase to an amorphous phase is called a reset.

The set and reset process requires two current pulses with different amplitudes and times. A large amplitude and short time set pulse raises the internal temperature of the phase change material above its melting point and allows the phase change material to become amorphous by allowing the liquid crystal structure to remain cool after the pulse is over. Set pulses with a relatively small amplitude and long time compared to reset pulses cause the phase change material to become a crystalline phase by raising the internal temperature of the phase change material above the crystallization temperature.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention is demonstrated according to drawing.

In addition, in description of this invention, the same code | symbol is attached | subjected to the same part and the repeated description is abbreviate | omitted.

A switch element as shown in FIG. 3 is constructed using the phase change material described above. 3 is a plan view of a nonvolatile programmable switch device including a phase change layer according to an embodiment of the present invention.

As shown in FIG. 3, the nonvolatile programmable switch device according to the present invention includes a metal layer connected to a first terminal 1, a second terminal 2, a first terminal 1, and a second terminal 2. 3), a conductive layer 4, a phase change layer 5 made of a phase change material, a third terminal 6 and a fourth terminal 7 connected to the phase change layer 5, respectively.

A part of the phase change layer 5 is located inside the contact hole 8 formed on the conductive layer 4, and the phase change is limited to the inside of the contact hole 8. The first terminal 1 and the second terminal 2 are connected to the metal layer 3 through the via hole 9. The third terminal 6 and the fourth terminal 7 are connected to the phase change layer 5 through the via hole 9. The phase change of the phase change material is caused by programming the switch element by applying an electric pulse through the first terminal 1 and the third terminal 6.

When a part of the phase change layer 5 located inside the contact hole 8 has a low resistance by set programming, the switch element is turned on and is electrically connected through the second terminal 2 and the fourth terminal 7. When the signal is transmitted and, conversely, the resistance is increased by reset programming, the switch element is turned off to interrupt the transmission of the electrical signal through the second terminal 2 and the fourth terminal 7.

Since the electrical resistance of GeSbTe, a typical phase change material, is hundreds of ohms and several M Ohms by set and reset programming, respectively, GeSbTe can be used to construct a switch device that serves to transmit and block an electrical signal. The conductive layer 4 serves to promote phase change of the phase change material during reset programming. Joule heat generated when the current flows inside the resistor is proportional to the resistance value, and the self-heating effect of the phase change material is very high because an amorphous phase with a large electrical resistance exists at the beginning of the set process. In addition, when the temperature of the phase change material rises only to the crystallization temperature, a crystalline phase is formed, thus enabling set programming with a relatively small current.

However, in the reset process, since the internal temperature of the phase change material must rise to the melting point in the presence of a crystal phase with a small electrical resistance, the current required for self-heating is very large. Contacting the conductive layer with the phase change material reduces the current required to induce a reset, as the thermal energy released from the conductive layer during programming promotes the temperature rise of adjacent phase change materials.

As described above, the switch element of the present invention uses a structure in which a programming terminal and a signal transmission terminal cross each other in a contact hole region in which a part of a phase change layer is located. To pass. Therefore, the set current is small compared with the prior art.

Next, a method for manufacturing a programmable switch element according to the present invention will be described.

4A to 4D are cross-sectional views and plan views of a unit cell for explaining a method of manufacturing a switch element according to the present invention.

Referring to FIG. 4A, a first insulating layer 101 is formed on the semiconductor substrate 100. When the semiconductor substrate is a Si wafer, a Si oxide film can be formed by a thermal oxidation method as the first insulating layer. The lower electrode 102 is deposited thereon, and the conductive layer 103 is deposited thereon. As the lower electrode 102, a material having low electrical resistivity, such as Al, Cu, W, TiW, or heavily doped Si, is used. The conductive layer 103 has a relatively high electrical resistivity compared to the lower electrode 102 such as TiN, TaN, TiAlN, WN, WBN, TiSiN, TaSiN, WSiN, TiSiC, TaSiC, WSiC, doped Si, and doped SiGe. Use substance.

Referring to FIG. 4B, the conductive layer 103 and the lower electrode 102 are patterned through a photolithography process and dry etching, and the conductive layer 103 is patterned through a photolithography process and dry etching. The first insulating layer 104 is formed thereon.

Referring to FIG. 4C, a portion of the first insulating layer 104 is removed through a photolithography process and dry etching to form a contact hole, and the phase change layer 105 and the upper electrode 106 are continuously deposited thereon. do. Phase change layers include chalcogenides such as GeTe, SbTe, SiTe, SbSe, InSe, GeSbTe, SiSbTe, InSbTe, GaSeTe, SnSbTe, GeSiSbTe, GeSnSbTe, GeSbSeTe, AgInSbTe, and antimony (Sb Ge) ZnSb and the like can be used, and each material is formed using sputtering or CVD. As the upper electrode 106, a material having a low electrical resistivity such as Al, Cu, W, TiW, or the like is used. The upper electrode 106 and the phase change layer 105 are patterned and a second insulating layer 107 is formed through a photolithography process and dry etching. Since the phase change layer 105 may have conductive properties using a subsequent heat treatment process, the upper electrode 106 is not an essential element constituting the switch element of the present invention and may not be used.

Referring to FIG. 4D, a portion of the second insulating layer 107 is removed through a photolithography process and dry etching to form a via hole 108, and a metal pad layer may be formed through metal thin film deposition, photolithography process, and dry etching. 109). A portion of the metal pad layer 109 is connected to the lower electrode 102 to become the first terminal 120 and the second terminal 121, and a portion of the other metal pad layer 109 is connected to the upper electrode 106. It becomes the 3rd terminal 122 and the 4th terminal 123. FIG.

5 is a view for explaining the operation of the switch element according to the present invention. When reset programming is performed through the first terminal 150 and the third terminal 152, an amorphous phase 154 having a large electrical resistance is formed in a portion of the phase change layer adjacent to the conductive layer. At this time, the switch element is in an off state, and transmission of an electrical signal through the second terminal 151 and the fourth terminal 153 is blocked. On the other hand, when the programming is set through the first terminal 150 and the third terminal 152, all or part of the amorphous phase is changed into a crystalline phase 155 having a low electrical resistance. In this case, the switch element is in an on state, and an electrical signal is transmitted through the second terminal 151 and the fourth terminal 153. Unlike the prior art, the switch device according to the present invention easily transfers an electrical signal between logic blocks even if only a part of the amorphous phase change material is changed into a crystalline phase by set programming.

6 is a cross-sectional view of a switch device according to another embodiment of the present invention. The switch device of FIG. 6 includes the first electrode 250, the second terminal 251, the first terminal 250, and the lower electrode 202 connected to the second terminal 251, the first conductive layer 203, The phase change layer 204, the second conductive layer 205, the upper electrode 206, and the third terminal 252 and the fourth terminal 253 connected to the upper electrode 206 are formed. The phase change layer 204 is formed between the first conductive layer 203 and the second conductive layer 205 by solid phase alloying of the materials constituting the first conductive layer 203 and the second conductive layer 205. For example, Ge and Sb are used to form GeSb as the phase change layer 204 material using the first conductive layer 203 and the second conductive layer 204 materials, respectively. After the first conductive layer 203 and the second conductive layer 205 are formed, heat treatment may be performed at any stage to form the phase change layer 204 by solid phase alloying. Since the second conductive layer 205 has conductive properties, the upper electrode 206 is not an essential element constituting the switch element of the present invention and may not be used.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

A nonvolatile programmable switch element comprising a phase change layer according to the present invention is used in a component of an electronic device.

1: first terminal 2: second terminal
3: metal layer 4: conductive layer
5: phase change layer 6: third terminal
7: fourth terminal 8: contact hole
9: via hole 100: semiconductor substrate

Claims (9)

A metal layer having a first terminal and a second terminal,
A conductive layer formed on the metal layer,
An insulating layer covering the conductive layer to form a contact hole exposing a portion of the upper portion of the conductive layer;
A buried phase change layer filling the contact hole and having a third terminal and a fourth terminal,
And the first terminal and the third terminal are programming terminals, the second terminal and the fourth terminal are signal transmission terminals, and the programming terminal and the signal transmission terminal cross each other in the contact hole region. device. The method of claim 1,
The phase change layer is a nonvolatile programmable switch device, characterized in that made of a material that is reversibly changed to an amorphous state and a crystal state according to the amount of current applied. The method of claim 2,
The material is a non-volatile programmable switch comprising a chalcogen compound including any one of sulfur (S), selenium (Se), and tellurium (Te) or an antimony compound including antimony (Sb). device. The method of claim 1,
The conductive layer is a nonvolatile programmable switch device comprising any one material selected from the group consisting of TiN, TaN, TiAlN, WN, WBN, TiSiN, TaSiN, WSiN, TiSiC, TaSiC, WSiC, Si, SiGe . A metal layer having a first terminal and a second terminal,
A first conductive layer formed on the metal layer,
An insulating layer covering the first conductive layer to form a contact hole exposing a portion of the upper portion of the first conductive layer,
A second conductive layer filling the contact hole and having a third terminal and a fourth terminal;
A phase change layer formed between the first conductive layer and the second conductive layer and formed by solid-phase alloying of a material constituting the first conductive layer and a material constituting the second conductive layer;
The first terminal and the third terminal is a programming terminal, the second terminal and the fourth terminal is a signal transmission terminal, the nonvolatile programmable switch device, characterized in that the programming terminal and the signal transmission terminal in the contact hole area intersect. . The method of claim 5,
The phase change layer is made of a nonvolatile compound comprising a chalcogen compound including any one of sulfur (S), selenium (Se), and tellurium (Te) or an antimony compound including antimony (Sb). Programmable switch element. Forming a metal layer having a first terminal and a second terminal,
Forming a conductive layer formed on the metal layer;
Forming an insulating layer covering the conductive layer to form a contact hole exposing a portion of the upper portion of the conductive layer;
Filling the contact hole, and forming a phase change layer having a third terminal and a fourth terminal,
The first terminal and the third terminal is a programming terminal, the second terminal and the fourth terminal is a signal transmission terminal, the method of manufacturing a nonvolatile programmable switch device in which the programming terminal and the signal transmission terminal crosses in the contact hole region. . Forming a metal layer having a first terminal and a second terminal,
Forming a first conductive layer formed on the metal layer;
Forming an insulating layer covering the first conductive layer to form a contact hole exposing a portion of the upper portion of the first conductive layer,
Filling the contact hole and forming a second conductive layer having a third terminal and a fourth terminal; and
Forming a phase change layer between the first conductive layer and the second conductive layer by solid phase alloying of the material constituting the first conductive layer and the material constituting the second conductive layer,
The first terminal and the third terminal is a programming terminal, the second terminal and the fourth terminal is a signal transmission terminal, the method of manufacturing a nonvolatile programmable switch device in which the programming terminal and the signal transmission terminal crosses in the contact hole region. . 9. The method according to claim 7 or 8,
The phase change layer is made of a nonvolatile compound comprising a chalcogen compound including any one of sulfur (S), selenium (Se), and tellurium (Te) or an antimony compound including antimony (Sb). Method of manufacturing a programmable switch element.

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