Resistive Memory

Abstract

The present invention provides a resistive memory, comprising a substrate, a first electrode, a second electrode, a variable resistance layer, and an oxygen storage layer. The first electrode is located on the substrate. The second electrode is located between the first electrode and the substrate. The variable resistance layer is located between the first electrode and the second electrode. The oxygen storage layer is located between the first electrode and the variable resistance layer. The oxygen storage layer includes a first portion, a second portion, and a third portion. The second portion is connected to one side of the first portion. The third portion is connected to the other side of the first portion. The thickness of the first portion is greater than the thickness of the second portion and the thickness of the third portion. The first portion of the oxygen storage layer protrudes toward the first electrode. The resistive memory can effectively improve the electrical performance of the memory element.

Description

Technical Field

[0001] The present invention relates to a semiconductor element, and in particular to a resistive memory. Background Art

[0002] Resistive memories (such as resistive random access memory (RRAM)) offer the potential advantages of low power consumption, high-speed operation, high density, and compatibility with complementary metal oxide semiconductor (CMOS) process technology, making them well-suited for next-generation memory devices. However, further improving the electrical performance of RRAM (e.g., maintaining a low current in the high resistance state (HRS) and increasing the current in the low resistance state (LRS)) remains a major challenge. Summary of the Invention

[0003] The present invention provides a resistive memory, which can effectively improve the electrical performance of memory elements.

[0004] The present invention provides a resistive memory, comprising a substrate, a first electrode, a second electrode, a resistance changeable layer, and an oxygen reservoir layer. The first electrode is located on the substrate. The second electrode is located between the first electrode and the substrate. The resistance changeable layer is located between the first electrode and the second electrode. The oxygen reservoir layer is located between the first electrode and the resistance changeable layer. The oxygen reservoir layer includes a first portion, a second portion, and a third portion. The second portion is connected to one side of the first portion. The third portion is connected to the other side of the first portion. The thickness of the first portion is greater than the thickness of the second portion and the thickness of the third portion. The first portion of the oxygen reservoir layer protrudes toward the first electrode.

[0005] According to an embodiment of the present invention, the resistive memory may further include an oxygen barrier layer located between the first electrode and the oxygen storage layer.

[0006] According to an embodiment of the present invention, in the resistive memory, the material of the oxygen barrier layer is, for example, aluminum oxide (Al2O3), silicon dioxide (SiO2), hafnium oxide (HfO2), or hafnium silicon nitride oxide (HfSiON).

[0007] According to one embodiment of the present invention, in the resistive memory, the material of the first electrode is, for example, titanium nitride (TiN), tantalum nitride (TaN), tungsten (W), hafnium nitride (HfN), aluminum nitride (AlN), iridium (Ir), platinum (Pt), or an iridium-platinum alloy (Pt / Ir).

[0008] According to an embodiment of the present invention, in the resistive memory, the material of the second electrode is, for example, titanium nitride (TiN), tantalum nitride (TaN), tungsten (W), hafnium nitride (HfN), or aluminum nitride (AlN).

[0009] According to one embodiment of the present invention, in the resistive memory, the material of the variable resistance layer is, for example, hafnium oxide (HfO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), a combination of hafnium oxide (HfO2) and aluminum oxide (Al2O3), or a combination of hafnium oxide (HfO2) and zirconium oxide (ZrO2).

[0010] According to an embodiment of the present invention, in the resistive memory, the material of the oxygen storage layer is, for example, titanium (Ti), tantalum (Ta), hafnium (Hf), or aluminum (Al).

[0011] According to an embodiment of the present invention, in the resistive memory, the shape of the oxygen storage layer may be a reverse T shape.

[0012] According to an embodiment of the present invention, in the resistive memory, the lower surface of the oxygen storage layer faces the variable resistance layer and may be a flat surface.

[0013] According to an embodiment of the present invention, in the resistive memory, the entire lower surface of the oxygen storage layer and the entire upper surface of the variable resistance layer may be in contact with each other.

[0014] According to an embodiment of the present invention, in the resistive memory, a ratio of a thickness of the first portion to a thickness of the second portion may be greater than 1 and less than or equal to 5.

[0015] According to an embodiment of the present invention, in the resistive memory, a ratio of a thickness of the first portion to a thickness of the third portion may be greater than 1 and less than or equal to 5.

[0016] According to an embodiment of the present invention, in the resistive memory, the thickness of the first portion may be 5 nm (nanometers) to 250 nm.

[0017] According to an embodiment of the present invention, in the resistive memory, the thickness of the second portion may be 5 nm to 50 nm.

[0018] According to an embodiment of the present invention, in the resistive memory, the thickness of the third portion may be 5 nm to 50 nm.

[0019] Based on the above, in the resistive memory device proposed in the present invention, the oxygen storage layer includes a first portion, a second portion, and a third portion. The thickness of the first portion is greater than that of the second and third portions, and the first portion of the oxygen storage layer protrudes toward the first electrode. This effectively improves the electrical performance of the memory device, as described below. After forming a conductive filament in the variable resistance layer, a high density of oxygen ions is formed in the thinner second and third portions of the oxygen storage layer. Therefore, during the initial reset (InitRST) operation, a lower bias voltage can be used to allow the oxygen ions to recombine with the conductive filament. Furthermore, the LRS current after the set (SET) operation can be increased by adjusting the thickness of the first, second, and / or third portions. Furthermore, since the second and third portions of the oxygen storage layer are thinner, the recombination distance between the oxygen ions and the conductive filament is shorter, thereby improving the efficiency of the reset (RST) operation. On the other hand, after the RST operation, the top diameter of the conductive filaments in the variable resistance layer adjacent to the thinner second and third portions is smaller. Therefore, oxygen ions re-bonded to the conductive filaments are less likely to diffuse into the oxygen storage layer, thus maintaining a stable low HRS current. Furthermore, in accelerated testing using high-temperature baking, the proposed resistive memory demonstrated excellent reliability.

[0020] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG. 4 is a cross-sectional view of a resistive memory according to an embodiment of the present invention.

[0022] Description of Figure Numbers:

[0023] 10: Resistive Memory

[0024] 100: Base

[0025] 102: first electrode

[0026] 104: second electrode

[0027] 106: variable resistance layer

[0028] 108: oxygen storage layer

[0029] 110: oxygen barrier layer

[0030] P1: Part 1

[0031] P2: Part 2

[0032] P3: Part 3

[0033] S1: lower surface

[0034] S2: upper surface

[0035] T1, T2, T3: thickness DETAILED DESCRIPTION

[0036] Figure 1 FIG. 4 is a cross-sectional view of a resistive memory according to an embodiment of the present invention.

[0037] Please refer to Figure 1 The resistive memory 10 includes a substrate 100, a first electrode 102, a second electrode 104, a variable resistance layer 106, and an oxygen storage layer 108. The substrate 100 may be a semiconductor substrate, such as a silicon substrate. Furthermore, depending on the product design, other desired film layers, interconnect structures, and / or components (e.g., active devices) (not shown) may be formed on the substrate 100.

[0038] The first electrode 102 is disposed on the substrate 100. The first electrode 102 may serve as the upper electrode of the resistive memory 10. The material of the first electrode 102 may be, for example, titanium nitride (TiN), tantalum nitride (TaN), tungsten (W), hafnium nitride (HfN), aluminum nitride (AlN), iridium (Ir), platinum (Pt), or an iridium-platinum alloy (Pt / Ir).

[0039] The second electrode 104 is located between the first electrode 102 and the substrate 100. The second electrode 104 may serve as the bottom electrode of the resistive memory 10. The material of the second electrode 102 may be, for example, titanium nitride (TiN), tantalum nitride (TaN), tungsten (W), hafnium nitride (HfN), or aluminum nitride (AlN).

[0040] The variable resistance layer 106 is located between the first electrode 102 and the second electrode 104. The material of the variable resistance layer 106 is, for example, hafnium oxide (HfO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), a combination of hafnium oxide (HfO2) and aluminum oxide (Al2O3), or a combination of hafnium oxide (HfO2) and zirconium oxide (ZrO2). Generally speaking, the operation of the resistive memory 10 may include the following stages, but the present invention is not limited thereto. Conductive filament formation stage: Conductive filaments are formed in the variable resistance layer 106, and the variable resistance layer 106 is in LRS. Initial reset (InitRST) stage: An InitRST operation is performed to convert the variable resistance layer 106 from LRS to HRS. Set (SET) stage: A SET operation is performed to convert the variable resistance layer 106 from HRS to LRS. Reset (RST) stage: A RST operation is performed to convert the variable resistance layer 106 from LRS to HRS.

[0041] The oxygen storage layer 108 is located between the first electrode 102 and the variable resistor layer 106. A lower surface S1 of the oxygen storage layer 108 faces the variable resistor layer 106 and can be a flat surface. Furthermore, the entire lower surface S1 of the oxygen storage layer 108 and the entire upper surface S2 of the variable resistor layer 106 can be in contact with each other, thereby increasing the range over which conductive filaments can be formed. The material of the oxygen storage layer 108 is, for example, titanium (Ti), tantalum (Ta), hafnium (Hf), or aluminum (Al).

[0042] The oxygen storage layer 108 includes a first portion P1, a second portion P2, and a third portion P3. The second portion P2 is connected to one side of the first portion P1. The third portion P3 is connected to the other side of the first portion P1. The thickness T1 of the first portion P1 is greater than the thickness T2 of the second portion P2 and the thickness T3 of the third portion P3. The first portion P1 of the oxygen storage layer 108 protrudes toward the first electrode 102. As a result, the shape of the oxygen storage layer 108 may be an inverted T-shape. In some embodiments, the second portion P2 and the third portion P3 may be connected to form a ring to surround the sidewall of the first portion P1. The ratio of the thickness T1 of the first portion P1 to the thickness T2 of the second portion P2 may be greater than 1 and less than or equal to 5. The ratio of the thickness T1 of the first portion P1 to the thickness T3 of the third portion P3 may be greater than 1 and less than or equal to 5. For example, the thickness T1 of the first portion P1 may be 5 nm to 250 nm, the thickness T2 of the second portion P2 may be 5 nm to 50 nm, and the thickness T3 of the third portion P3 may be 5 nm to 50 nm.

[0043] In addition, the resistive memory 10 may further include an oxygen barrier layer 110. The oxygen barrier layer 110 is located between the first electrode 102 and the oxygen storage layer 108. The material of the oxygen barrier layer 110 is, for example, aluminum oxide (Al2O3), silicon dioxide (SiO2), hafnium dioxide (HfO2), or hafnium silicon nitride oxide (HfSiON).

[0044] Based on the above embodiments, it can be seen that in the resistive memory device 10, the oxygen storage layer 108 includes a first portion P1, a second portion P2, and a third portion P3. The thickness T1 of the first portion P1 is greater than the thickness T2 of the second portion P2 and the thickness T3 of the third portion P3. Furthermore, the first portion P1 of the oxygen storage layer 108 protrudes toward the first electrode 102. This effectively improves the electrical performance of the memory device, as described below.

[0045] After forming the conductive filament in the variable resistance layer 106 , high-density oxygen ions can be formed in the thinner second portion P2 and third portion P3 of the oxygen storage layer 108 . Therefore, during the InitRST operation, a smaller bias voltage can be used to allow the oxygen ions to recombine with the conductive filament.

[0046] In addition, the current of the LRS after the SET operation may be increased by adjusting the thickness T1 of the first portion P1 , the thickness T2 of the second portion P2 , and / or the thickness T3 of the third portion P3 .

[0047] In addition, during the RST operation, since the thickness of the second portion P2 and the third portion P3 of the oxygen storage layer 108 is relatively thin, the recombination distance between the oxygen ions and the conductive filaments is relatively short, thereby improving the efficiency of the RST operation.

[0048] On the other hand, because the thickness T1 of the first portion P1 is greater than the thickness T2 of the second portion P2 and the thickness T3 of the third portion P3, conductive filaments of different sizes can be formed in the variable resistance layer 106. The top diameters of the conductive filaments in the variable resistance layer 106 adjacent to the thinner second portion P2 and third portion P3 are smaller, while the top diameters of the conductive filaments in the variable resistance layer 106 adjacent to the thicker first portion P1 are larger. After the RST operation, since the top diameters of the conductive filaments in the variable resistance layer 106 adjacent to the thinner second portion P2 and third portion P3 are smaller, oxygen ions re-bonded to the conductive filaments are less likely to diffuse into the oxygen storage layer 108, thereby stably maintaining a low current in the HRS.

[0049] On the other hand, in an accelerated test performed by high-temperature baking, the resistive memory 10 has excellent reliability.

[0050] In summary, in the resistive memory proposed in the above embodiments, the thickness of the first portion is greater than the thickness of the second portion and the thickness of the third portion, and the first portion of the oxygen storage layer protrudes toward the first electrode, thereby effectively improving the electrical performance of the memory element.

[0051] Although the present invention has been disclosed above by way of embodiments, they are not intended to limit the present invention. Any person skilled in the art may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A resistive memory, characterized in that: include: substrate; a first electrode, located on the substrate; a second electrode, located between the first electrode and the substrate; a variable resistance layer, located between the first electrode and the second electrode; as well as an oxygen storage layer, located between the first electrode and the variable resistance layer, and comprising: Part I; a second portion connected to one side of the first portion; and a third portion connected to the other side of the first portion, wherein the thickness of the first portion is greater than the thickness of the second portion and the thickness of the third portion, the first portion of the oxygen storage layer protrudes toward the first electrode, and the second portion and the third portion each have a flat top surface in a cross-sectional view.

2. The resistive memory according to claim 1, wherein: Also includes: The oxygen barrier layer is located between the first electrode and the oxygen storage layer.

3. The resistive memory according to claim 2, wherein: The material of the oxygen barrier layer includes aluminum oxide, silicon dioxide, hafnium dioxide or hafnium oxide silicon nitride.

4. The resistive memory according to claim 1, wherein: The material of the first electrode includes titanium nitride, tantalum nitride, tungsten, hafnium nitride, aluminum nitride, iridium, platinum or iridium-platinum alloy.

5. The resistive memory according to claim 1, wherein: The material of the second electrode includes titanium nitride, tantalum nitride, tungsten, hafnium nitride or aluminum nitride.

6. The resistive memory according to claim 1, wherein: The material of the variable resistance layer includes hafnium oxide, aluminum oxide, zirconium oxide, a combination of hafnium oxide and aluminum oxide, or a combination of hafnium oxide and zirconium oxide.

7. The resistive memory according to claim 1, wherein: The material of the oxygen storage layer includes titanium, tantalum, hafnium or aluminum.

8. The resistive memory according to claim 1, wherein: The shape of the oxygen storage layer includes an inverted T-shape.

9. The resistive memory according to claim 1, wherein: The lower surface of the oxygen storage layer faces the variable resistance layer and is a flat surface.

10. The resistive memory according to claim 1, wherein: An entire lower surface of the oxygen storage layer and an entire upper surface of the variable resistance layer are in contact with each other.

11. The resistive memory according to claim 1, wherein: A ratio of a thickness of the first portion to a thickness of the second portion is greater than 1 and less than or equal to 5.

12. The resistive memory according to claim 1, wherein: A ratio of a thickness of the first portion to a thickness of the third portion is greater than 1 and less than or equal to 5.

13. The resistive memory according to claim 1, wherein: The thickness of the first portion is 5 nanometers to 250 nanometers.

14. The resistive memory according to claim 1, wherein: The thickness of the second portion is 5 nanometers to 50 nanometers.

15. The resistive memory according to claim 1, wherein: The thickness of the third portion is 5 nanometers to 50 nanometers.

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