Diode structure and memory device including the same

Provided are a diode structure and a memory device including the same. The diode structure includes: a first electrode; a p-type Cu oxide layer formed on the first electrode; an n-type InZn oxide layer formed on the p-type Cu oxide layer; and a second electrode formed on the n-type InZn oxide.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2007-0082989, filed on Aug. 17, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a diode structure and a memory device including the same, and more particularly, to a new diode structure including a compound of material having an excellent rectification property, and a memory device including the new diode structure.

2. Description of the Related Art

Many semiconductor devices comprising semiconductor memories include a switching structure. For example, a dynamic random access memory (DRAM), which is a representative memory device, includes among other elements a switching structure and a capacitor. A transistor, a diode, a varistor, and the like are examples of the switching structure.

To realize a highly integrated semiconductor device able to store mass information in a small area, a switching structure having a simple structure is required. In particular, a device such as a resistive random access memory device, which has recently undergone much research, has a cross-point structure in order to maximize integration.

A diode used for a semiconductor device preferably has a high current density in order to improve integration of the semiconductor device, a low leakage current due to a high ON/OFF current ratio, and a short response time with respect to a pulse signal.

SUMMARY OF THE INVENTION

The present invention provides a semiconductor diode including a new material and thus having an excellent rectification property and a short response speed, and a memory device including the semiconductor diode.

The present invention also provides a diode structure, including: a first electrode; a p-type Cu oxide layer formed on the first electrode; an n-type InZn oxide layer formed on the p-type Cu oxide layer; and a second electrode formed on the n-type InZn oxide.

The p-type Cu oxide layer may include CuO.

The n-type InZn oxide layer may include In2Zn2O5.

The first electrode and the second electrode may be formed of a metal or a conductive metal oxide.

According to another aspect of the present invention, there is provided a resistive random access memory device including: a first electrode; a first p-type Cu oxide layer formed on the first electrode; an n-type InZn oxide layer formed on the p-type Cu oxide layer; a second p-type Cu oxide layer formed on the n-type InZn oxide; a variable resistance layer formed on the second electrode; and a third electrode formed on the variable resistance layer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference to the accompanying drawings according to embodiments of the present invention. In the drawings, the thicknesses of layers and regions are exaggerated for clarity.

FIG. 1is a cross-sectional view illustrating a diode structure according to an embodiment of the present invention.

Referring toFIG. 1, a diode structure according to an embodiment of the present invention includes a first electrode11, a p-type Cu oxide layer12formed on the first electrode11, an n-type InZn oxide layer13formed on the p-type Cu oxide layer12, and a second electrode14formed on the n-type InZn oxide layer13.

A method of manufacturing the diode structure according to an embodiment of the present invention will now be described. First, the first electrode11is formed of a conductive material such as a metal or a metal oxide. For example, the first electrode11may be formed of Al, Hf, Zr, Zn, W, Co, Au, Pt, Ru, Ir, Ti, or a conductive metal oxide. The p-type Cu oxide layer12, for example, p-type CuO, and the n-type InZn oxide layer13, for example, n-type InZnO, are formed on an upper portion of the first electrode11. Similarly to the first electrode11, a second electrode14is formed of a conductive material such as a metal or metal oxide on the n-type InZn oxide layer13. The diode structure according to an embodiment of the present invention may be formed by a physical vapor deposition (PVD) method, an atomic layer deposition (ALD) method, or a chemical vapor deposition (CVD) method.

An electric property of a diode structure according to an embodiment of the present invention will now be described with reference toFIG. 3. Here, both of the first electrode11and the second electrode14of the diode structure are formed of Pt. In the graph ofFIG. 3, the horizontal axis represents the size of voltage applied to both end portions of the first electrode11and the second electrode14, and the vertical axis represents current density (A/cm2).

Referring toFIG. 3, the diode structure according to an embodiment of the present invention has a high forward current density of more than 3*104A/cm2at about 1.2V, and has an forward/reverse current ratio value of more than 104. As a result, the diode structure according to an embodiment of the present invention has an excellent rectification property, and thereby can be used in semiconductor memory devices.

FIG. 2is a cross-sectional view illustrating a resistive random access memory device including a diode structure according to an embodiment of the present invention. The diode structure according to an embodiment of the present invention can be used in various semiconductor devices as well as in resistive random access memory devices.

Referring toFIG. 2, the diode structure includes a first electrode21, a p-type Cu oxide layer22formed on the first electrode21, an n-type InZn oxide layer23formed on the p-type Cu oxide layer22, a second electrode24formed on the n-type InZn oxide layer23, a variable resistance layer25formed on the second electrode24, and a third electrode26formed on the variable resistance layer25.

The variable resistance layer25may be formed of variable resistance material used in general resistive random access memory devices. The variable resistance material has more than two resistance values when current is applied. The variable resistance layer25may be formed of a transition metal oxide (TMO) such as Ni oxide, Ti oxide, Hf oxide, Zr oxide, Zn oxide, W oxide, Co oxide, Cu oxide, Nb oxide, and the like, and also may be formed of a perovskite metal oxide (SrTiO3, (Pr,Ca)MnO3, BaTiO3, PbTiO3) and the like.

Similarly to the first electrode21and the second electrode24, the third electrode26may be formed of Al, Hf, Zr, Zn, W, Co, Au, Pt, Ru, Ir, Ti, or a conductive metal oxide.

FIG. 4is a graph illustrating an electric property of a resistive random access memory device including a diode structure ofFIG. 1. Referring toFIG. 4, when a positive voltage and a negative voltage are respectively applied to electrodes at both end portions of the resistive random access memory device, a plot of current values with respect to the positive voltage is asymmetric with respect to a plot of current values with respect to the negative voltage.

FIG. 5is an image illustrating an operational property with respect to a pulse signal of a diode structure according to an embodiment of the present invention. In the present embodiment, the diode structure uses Pt as a lower electrode and an upper electrode, and includes CuO/InZnO formed between the lower electrode and the upper electrode. When a pulse signal is applied to the lower electrode and the upper electrode, an output signal of about 10 ns is generated, the diode structure thus having a short response time.

According to the present invention, a semiconductor diode having an excellent rectification property and a short response time is provided. Also, a resistive random access memory device having a highly integrated 1D (diode)-1R (resistance) structure is provided by using the semiconductor diode.