CN114695658A - A kind of RRAM device and its manufacturing method - Google Patents

Abstract

The invention provides an RRAM device and a method for manufacturing the same. A substrate is provided on which a first metal electrode is formed; a first oxide layer is formed on the surface of the first metal electrode; and the first oxide layer is continuously oxidized to make the first oxide layer The upper layer of the layer is formed as a second oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer; and a second metal electrode is formed on the surface of the second oxide layer. The invention adopts tantalum oxide physical vapor deposition process and oxidation process to change the valence state distribution of tantalum in the resistive change material, so as to improve the resistive change material to reduce the forming voltage and increase the storage window.

Description

A kind of RRAM device and its manufacturing method

technical field

The present invention relates to the technical field of semiconductors, in particular to an RRAM device and a manufacturing method thereof.

Background technique

RRAM (Resistive Random Access Memory) utilizes two or more different resistance states exhibited by some thin film materials under the action of an external electric field to realize data storage. A new type of non-volatile memory that is widely concerned by the industry, its typical structure is metal electrode-oxide-metal electrode. Under the excitation of an external electric field, the device can undergo a reversible transition between high and low resistance states, and its high and low resistance states can still be maintained after the electric field is removed. RRAM has multiple advantages such as fast erasing and writing speed, high storage density, high number of repeated erasing and writing, multi-value storage and three-dimensional storage. Under the excitation of an external electric field, the device can undergo a reversible transition between high and low resistance states, and its high and low resistance states can still be maintained after the electric field is removed. The forming process refers to the process of RRAM jumping from the initial high-resistance state to the low-resistance state for the first time. On the contrary, the RRAM in the low-resistance state can be converted to the high-resistance state after being excited by a certain voltage, and the low-resistance state The process of state transition to high impedance state is called Reset. After the Reset process, the RRAM entering the high-impedance state can also be converted to the low-impedance state by applying voltage excitation, and this process is different from the first high-impedance transition to the low-impedance state, which is called the Set (reset) process.

However, the forming voltage of the currently used tantalum oxidation process and PVD (physical vapor deposition) process is too high to meet the maximum voltage limit provided by the 40nm process. The defects of the tantalum oxidation process are that the degree of oxidation is not easy to control, the oxidation time is too short, and the tantalum oxidation Insufficient, reducing the thickness of the resistive switching layer, there is a risk of breakdown; if the oxidation time is too long, the lower electrode is easily oxidized, increasing the thickness of the resistive switching layer, causing the forming voltage to be too high. (shown in Figure 1A to Figure 1C)

The disadvantage of the PVD process is that the forming voltage increases, which cannot meet the high-voltage limitation of the process.

Therefore, a new method is needed to change the valence state distribution of tantalum in resistive materials, so as to improve the resistive materials to reduce the forming voltage and increase the storage window.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a RRAM device and a manufacturing method thereof, which are used to solve the problem that the forming voltage of the tantalum oxidation process and the PVD (physical vapor deposition) process in the prior art is too high and cannot be To meet the maximum voltage limit provided by the 40nm process, the defects of the tantalum oxidation process are that the degree of oxidation is not easy to control, the oxidation time is too short, the oxidation of tantalum is insufficient, the thickness of the resistive layer is reduced, and there is a risk of breakdown; if the oxidation time is too long, the power off It is very easy to be oxidized, increasing the thickness of the resistive layer, causing the problem of too high forming voltage.

In order to achieve the above-mentioned purpose and other related purposes, the present invention provides a manufacturing method for improving the properties of the resistive material of the RRAM device, including:

Step 1, providing a substrate on which a first metal electrode is formed;

Step 2, forming a first oxide layer on the surface of the first metal electrode;

Step 3: Continue to oxidize the first oxide layer, so that the upper layer of the first oxide layer is oxidized into a second oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer;

Step 4, forming a second metal electrode on the surface of the second oxide layer.

Preferably, the substrate in step 1 is a silicon substrate.

Preferably, the material of the first metal electrode in step 1 is tantalum nitride.

Preferably, the material of the first oxide layer in step 2 is tantalum oxide.

Preferably, in step 3, the mixed gas of oxygen and rare gas is used to control the valence state of metal ions in the second oxide layer.

Preferably, the rare gas in step 3 is argon.

Preferably, the ratio of oxygen to argon in step 3 is any one of 20:25, 15:25, 10:25, 8:25, and 5:25.

Preferably, the material of the second metal electrode in step 4 is titanium nitride.

An RRAM device structure, which can be manufactured by the method of any of the above steps, comprising:

a substrate, on which a first metal electrode is formed;

A first oxide layer is formed on the surface of the first metal electrode;

A second oxide layer is formed on the upper surface of the first oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer;

A second metal electrode is formed on the surface of the second oxide layer.

Preferably, the substrate is a silicon substrate.

Preferably, the material of the first oxide layer is tantalum oxide.

Preferably, the material of the first metal electrode is tantalum nitride.

Preferably, the material of the second metal electrode is titanium nitride.

As mentioned above, the manufacturing method of the present invention for improving the properties of the resistive material of the RRAM device has the following beneficial effects:

The invention adopts the tantalum oxide physical vapor deposition process and the oxidation process to change the valence state distribution of tantalum in the resistance change material, so as to improve the resistance change material to reduce the forming voltage and increase the storage window.

Description of drawings

1A to C show a schematic diagram of a tantalum oxidation process in the prior art;

Fig. 2 shows the process flow schematic diagram of the present invention;

FIG. 3 is a schematic diagram showing the formation of the first metal electrode according to the present invention;

4 is a schematic diagram showing the formation of the first oxide layer of the present invention;

5 is a schematic diagram showing the formation of the second oxide layer according to the present invention;

FIG. 6 is a schematic diagram showing the formation of the second metal electrode according to the present invention;

FIG. 7 is a schematic diagram showing the formation method of the second oxide layer of the present invention;

FIG. 8 is a schematic diagram showing the working principle of the device of the present invention.

Detailed ways

The embodiments of the present invention are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

Referring to FIG. 2, the present invention provides a manufacturing method for improving the properties of a resistive material of an RRAM device, including:

Step 1, please refer to FIG. 3, provide a substrate (not shown in the figure), and a first metal electrode is formed on the substrate;

In an optional implementation manner, the substrate in step 1 is a silicon substrate, and the first metal electrode may be formed on the silicon substrate, or after the epitaxial layer is formed on the silicon substrate, the epitaxial layer may be formed on the epitaxial layer. A first metal electrode is formed.

In an optional embodiment, the material of the first metal electrode in step 1 is tantalum nitride.

It should be understood that the material of the first metal electrode here also adopts other types of materials.

Step 2, please refer to FIG. 4, forming a first oxide layer on the surface of the first metal electrode;

In an optional embodiment, the material of the first oxide layer in step 2 is tantalum oxide.

It should be understood that the material of the first oxide layer here also adopts other types of materials.

Step 3, referring to FIG. 5, continue to oxidize the first oxide layer, so that the upper layer of the first oxide layer is oxidized to form a second oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer;

In an optional embodiment, in step 3, the mixed gas of oxygen and rare gas is used to control the valence state of metal ions in the second oxide layer, and the reaction of tantalum with oxygen can generate TaO, TaO2 and Ta2O5. The ratio of the gas can control the concentration of oxygen, thereby controlling the products generated by the reaction of tantalum and oxygen.

In an optional embodiment, the rare gas in step 3 is argon.

It should be understood that other types of inert gases are also used for the rare gas here.

In an optional embodiment, referring to FIG. 7 , in step 3, the ratio of oxygen to argon is any one of 20:25, 15:25, 10:25, 8:25, and 5:25, The generation ratio of TaO, TaO2 and Ta2O5 can be controlled.

Step 4, referring to FIG. 6 , a second metal electrode is formed on the surface of the second oxide layer.

Referring to FIG. 8, after the RRAM device structure is formed according to any of the above steps, the oxide resistive material of tantalum is formed through the conductive channel because the lattice oxygen near the interface between the oxide and the electrode is excited under the action of a strong electric field It ran into the electrode and left a vacancy, and then the lattice oxygen near the place affected by the field was excited and ran into the electrode and left a vacancy, and then the oxygen in the attachment was migrated to this oxygen vacancy position by the electric field, so it can be equivalent to For the diffusion of oxygen vacancies from one electrode to the inside of the oxide, a conductive channel connecting the two electrodes is finally formed. The disconnection of the conductive channel is formed by the recombination of cations and oxygen vacancies under the action of the reverse electric field.

In this embodiment, due to the high oxygen content in the upper half of the resistive switching layer, the lattice oxygen is more easily excited to run into the electrode under the action of the electric field, leaving oxygen vacancies, and then the oxygen in the accessories migrates to the oxygen vacancies under the action of the electric field. Finally, the oxygen vacancy conduction channel is formed, which effectively reduces the forming voltage.

In this embodiment, during reset, the reset voltage will also decrease under the action of the reverse electric field and the oxygen concentration gradient.

In this embodiment, due to the increase of the oxygen content of the resistive material, the resistance of the high configuration will also increase, while the low configuration is a conductive channel formed by oxygen vacancies, and the oxygen content has little influence, so the storage window is also increased.

In an optional embodiment, the material of the second metal electrode in step 4 is titanium nitride.

It should be understood that the material of the second metal electrode here also adopts other types of materials.

An RRAM device structure, which can be manufactured by the method of any of the above steps, comprising:

a substrate, on which a first metal electrode is formed;

A first oxide layer is formed on the surface of the first metal electrode;

A second oxide layer is formed on the upper surface of the first oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer;

A second metal electrode is formed on the surface of the second oxide layer.

In an optional embodiment, the substrate is a silicon substrate.

In an optional embodiment, the material of the first oxide layer is tantalum oxide.

In an optional embodiment, the material of the first metal electrode is tantalum nitride.

In an optional embodiment, the material of the second metal electrode is titanium nitride.

It should be noted that the drawings provided in this embodiment are only to illustrate the basic concept of the present invention in a schematic way, so the drawings only show the components related to the present invention rather than the number, shape and the number of components in actual implementation. For dimension drawing, the type, quantity and proportion of each component can be changed at will in actual implementation, and the component layout may also be more complicated.

To sum up, the present invention adopts a tantalum oxide physical vapor deposition process and an oxidation process to change the valence state distribution of tantalum in the resistive material to improve the resistive material to reduce the forming voltage and increase the storage window. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still be covered by the claims of the present invention.

Claims (13)

1. A RRAM device structure, comprising:

a substrate on which a first metal electrode is formed;

a first oxide layer is formed on the surface of the first metal electrode;

a second oxide layer is formed on the upper surface of the first oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer;

and a second metal electrode is formed on the surface of the second oxide layer.

2. The RRAM device structure of claim 1, wherein: the substrate is a silicon substrate.

3. The RRAM device structure of claim 1, wherein: the first oxide layer is made of tantalum oxide.

4. The RRAM device structure of claim 1, wherein: the first metal electrode is made of tantalum nitride.

5. The RRAM device structure of claim 1, wherein: the second metal electrode is made of titanium nitride.

6. The method of manufacturing a RRAM device according to any one of claims 1 to 5, characterized by comprising at least:

providing a substrate, wherein a first metal electrode is formed on the substrate;

step two, forming a first oxide layer on the surface of the first metal electrode;

oxidizing the first oxide layer, and oxidizing the upper surface of the first oxide layer to form a second oxide layer, wherein the oxygen content of the second oxide layer is greater than that of the first oxide layer;

and fourthly, forming a second metal electrode on the surface of the second oxide layer.

7. The manufacturing method for improving the resistance change material characteristics of the RRAM device according to claim 6, wherein: the substrate in the first step is a silicon substrate.

8. The manufacturing method for improving the resistance change material characteristics of the RRAM device according to claim 6, wherein: in the first step, the first metal electrode is made of tantalum nitride.

9. The manufacturing method for improving the resistance change material characteristics of the RRAM device according to claim 6, wherein: in the second step, the first oxide layer is made of tantalum oxide.

10. The manufacturing method for improving the resistance change material characteristics of the RRAM device according to claim 6, wherein: in the third step, the valence state of the metal ions in the second oxide layer is controlled by using the mixed gas of oxygen and rare gas.

11. The manufacturing method for improving the resistance change material characteristics of the RRAM device according to claim 10, wherein: in the third step, the rare gas is argon.

12. The manufacturing method for improving the characteristics of the resistive material of the RRAM device as claimed in claim 11, wherein: in the third step, the ratio of oxygen to argon is 20:25, 15:25, 10:25, 8:25, 5:25, respectively.

13. The manufacturing method for improving the resistance change material characteristics of the RRAM device according to claim 6, wherein: in the fourth step, the second metal electrode is made of titanium nitride.

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