A method for reducing leakage of hzo ferroelectric capacitor and improving reliability by microwave treatment

Abstract

The application discloses a method for reducing leakage of HZO ferroelectric capacitor and improving reliability by microwave treatment, and the method comprises the following steps: first step, applying a cycle voltage with a certain voltage and frequency to the HZO ferroelectric capacitor; second step, after the cycle voltage is applied, microwave treatment with a certain time, power and frequency is carried out; the microwave treatment in the application can effectively reduce the leakage of the ferroelectric capacitor after the cycle voltage is applied; with the extension of the microwave time, the leakage of the ferroelectric capacitor after the cycle voltage is applied is gradually reduced; the method innovatively proposes to redistribute the oxygen vacancies by microwave regulation, so that the leakage current can be reduced after the leakage current is increased, and no new defects are generated, thereby effectively reducing the leakage and avoiding breakdown.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a method for reducing leakage of HZO ferroelectric capacitor and improving reliability by microwave treatment. BACKGROUND

[0002] Ferroelectric capacitor made of new hafnium-based ferroelectric material hafnium-zirconium oxide (HZO) has many advantages that have aroused widespread attention in the industry, such as lower relative dielectric constant, which can provide better charge storage performance, smaller leakage current, which can bring lower power consumption, and good process compatibility, which can make it easier to integrate into integrated circuits. However, the leakage of HZO ferroelectric capacitor gradually increases after being applied with continuous voltage pulses, and the main reason for the increase in leakage is the increase in oxygen vacancies. When oxygen vacancies are concentrated and form conductive channels, the ferroelectric capacitor will be broken down and lose its working ability. Therefore, how to reduce the leakage current of HZO ferroelectric capacitor, improve the anti-breakdown capability of the device, and enhance the durability of the device is a problem that needs to be solved in the industry.

[0003] As can be seen from the above analysis, the leakage current of the ferroelectric capacitor made of HZO material increases after being applied with continuous voltage pulses, which is a key factor that seriously restricts the application of HZO ferroelectric capacitor. How to reduce the leakage and improve the anti-breakdown capability is a problem that needs to be solved.

[0004] To solve the above problems, in the prior art, the first path is mainly to improve the material quality by optimizing the process parameters during preparation, including adjusting the component ratio of HZO material during atomic layer deposition (ALD) growth process, selecting rapid thermal annealing method, and changing annealing atmosphere and annealing temperature. However, the HZO ferroelectric capacitor made by the above improvement method still shows the phenomenon of gradually increasing leakage with the increasing number of applied voltage pulses during work, and cannot effectively solve the leakage problem. Another path is to redistribute oxygen vacancies by applying a small amplitude voltage when the leakage of the ferroelectric capacitor increases. However, small amplitude voltage can also cause defects, and the leakage will gradually increase with the increasing number of small amplitude voltage applications.

[0005] Therefore, the purpose of the present application is to solve the problems of the prior art, and provide a method for reducing leakage of HZO ferroelectric capacitor and improving reliability by microwave treatment. The oxygen vacancies are redistributed by microwave method when the leakage of the ferroelectric capacitor increases, which can effectively avoid the breakdown of HZO ferroelectric capacitor and improve the reliability. SUMMARY

[0006] Aiming at the defects in the prior art, the purpose of the present application is to provide a method for reducing leakage of HZO ferroelectric capacitor and improving reliability by microwave treatment, which can effectively avoid breakdown of HZO ferroelectric capacitor and improve reliability by redistributing oxygen vacancies through microwave after leakage of the ferroelectric capacitor increases, reducing leakage and not producing new defects.

[0007] Specifically, the technical problem to be solved by the present application is that, aiming at the defects in the prior art, the present application provides a method for reducing leakage of HZO ferroelectric capacitor and improving reliability by microwave treatment, which can effectively avoid breakdown of HZO ferroelectric capacitor and improve reliability by redistributing oxygen vacancies through microwave after leakage of the ferroelectric capacitor increases, reducing leakage and not producing new defects.

[0008] The second step is to apply microwave treatment with a certain time, power and frequency after the cyclic voltage is applied.

[0009] Preferably, the HZO ferroelectric capacitor comprises a substrate material layer, a bottom metal layer, a HZO layer and a top metal layer which are stacked in sequence, wherein the thickness of the HZO layer is 6-12nm.

[0010] Preferably, the substrate material layer is an N-type heavily doped substrate, the material is Si or Ge, and the thickness is 700-800um.

[0011] Preferably, the bottom metal layer and the top metal layer are of the same material, and the material is TiN or W, wherein the thickness of the bottom metal layer is 30-60nm, and the thickness of the top metal layer is 30-60nm.

[0012] Preferably, the voltage amplitude of the cyclic voltage is ±2V-±3V.

[0013] Preferably, the frequency of the cyclic voltage is 1kHz-100kHz.

[0014] Preferably, the time of the microwave treatment is 120s-600s.

[0015] Preferably, the power of the microwave treatment is 400W-1800W.

[0016] Preferably, the frequency of the microwave treatment is 1000MHz-2000MHz.

[0017] Compared with the prior art, the positive effects of the present application are: (1) Firstly, the existing method for reducing the leakage of ferroelectric capacitors in the present application is to improve the quality of ferroelectric capacitors by process optimization during preparation, but the leakage of the ferroelectric capacitors made by this method will still increase after working; the oxygen vacancy redistribution is carried out by small voltage, but new defects will still be generated under small voltage, which reduces the reliability problem; the method in the present application innovatively proposes to redistribute the oxygen vacancy by microwave regulation, which can reduce the leakage current after the leakage current has increased, and will not generate new defects, effectively reducing the leakage to avoid breakdown.

[0018] (2) Secondly, in the method of the present application, with the extension of the microwave treatment time, the leakage of the ferroelectric capacitor after the application of voltage cycle gradually decreases. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a cross-sectional schematic diagram of the HZO capacitor in the present application.

[0020] Figure 2 is a cross-sectional schematic diagram of the HZO capacitor in the embodiment of the present application.

[0021] Figure 3 is a schematic diagram of the cycle voltage waveform applied to the HZO capacitor in the embodiment of the present application and the schematic diagram of the microwave applied.

[0022] Figure 4 is the measurement result under the leakage measurement voltage in the embodiment of the present application. DETAILED DESCRIPTION

[0023] The present application will be further described below in combination with the specific embodiments. Figures 1-4 and the specific embodiments.

[0024] The leakage of the ferroelectric capacitor in the prior art will gradually increase after being applied with continuous voltage pulses, and the main reason for the increase of the leakage is the increase of oxygen vacancies. When oxygen vacancies are concentratedly distributed and form conductive channels, the ferroelectric capacitor will be broken down and lose the working ability. Therefore, how to reduce the leakage current of the ferroelectric capacitor, improve the anti-breakdown ability of the device, and enhance the durability of the device is a problem to be solved in the industry.

[0025] As can be seen from the above analysis, the leakage current generated by the ferroelectric capacitor after being applied with continuous voltage pulses increases, which is a key factor that seriously restricts the application of ferroelectric capacitors. How to reduce the leakage and improve the anti-breakdown ability is a problem to be solved.

[0026] To address the aforementioned problems, the first approach in existing technologies primarily involves improving material quality by optimizing process parameters during fabrication. This includes adjusting the component ratios during atomic layer deposition (ALD) growth, employing rapid thermal annealing, and altering the annealing atmosphere and temperature. However, ferroelectric capacitors fabricated using these improved methods still exhibit a gradual increase in leakage current with the number of applied electrical pulses, failing to effectively resolve the leakage problem. Another approach involves redistributing oxygen vacancies by applying cyclic small-amplitude voltages when the leakage current increases. However, even small-amplitude voltages can induce defects, and the leakage current gradually increases with the number of small-amplitude voltage applications.

[0027] To address the aforementioned problems, this invention innovatively employs a method for reducing leakage current in ferroelectric capacitors and improving reliability through microwave processing. The method includes the following steps: After detecting an increase in leakage current in the ferroelectric capacitor, the leakage current is reduced using the following method: Step 1: Applying a cyclic voltage of a certain voltage and frequency to the ferroelectric capacitor; Step 2: After applying the cyclic voltage, performing microwave processing for a certain time, power, and frequency.

[0028] The ferroelectric capacitor is preferably an HZO ferroelectric capacitor, which comprises a substrate material layer, a bottom metal layer, an HZO layer, and a top metal layer stacked sequentially, wherein the thickness of the HZO layer is 6-12 nm; for example Figure 1 The figure shown is a cross-sectional schematic diagram of the HZO capacitor in this invention.

[0029] The substrate material layer is an N-type heavily doped substrate, made of Si or Ge, with a thickness of 700-800 μm.

[0030] The bottom metal layer and the top metal layer are made of the same material, which is TiN or W. The thickness of the bottom metal layer is 30-60 nm, and the thickness of the top metal layer is 30-60 nm.

[0031] The voltage amplitude of the cyclic voltage is ±2V to ±3V; the frequency of the cyclic voltage is 1kHz to 100kHz.

[0032] The microwave processing time is 120s to 600s; the microwave processing power is 400W to 1800W; and the microwave processing frequency is 1000MHz to 2000MHz.

[0033] Example: This invention takes an HZO ferroelectric capacitor as an example. The HZO ferroelectric capacitor includes a substrate material layer, a bottom metal layer, an HZO layer, and a top metal layer stacked sequentially. The HZO layer has a thickness of 10 nm; the substrate material layer is N-type heavily doped Si with a thickness of 700 nm; the top and bottom metal layers are TiN, and both metal layers have a thickness of 50 nm. Figure 2 The figure shown is a cross-sectional schematic diagram of the HZO capacitor in an embodiment of the present invention.

[0034] After 10 HZO ferroelectric capacitors 5 After a voltage cycle at a frequency of 1kHz and a voltage amplitude of ±2V, the device is subjected to microwave processing. The microwave processing power is 900W, the frequency is 1200MHz, and the duration is 0s, 120s, 300s, and 600s. After microwave processing, the leakage current is measured using a leakage current measurement voltage of -2V to obtain the measurement results. Figure 3 The diagram shows a schematic of the cyclic voltage waveform applied to the HZO capacitor and a schematic of the microwave application according to an embodiment of the present invention; as shown. Figure 4 The figure shows the measurement results under the leakage current measurement voltage in an embodiment of the present invention.

[0035] exist Figure 4 In this diagram, the horizontal axis represents the leakage current measurement voltage, and the vertical axis represents the different leakage currents corresponding to different leakage current measurement voltages. Figure 4 Each curve in the graph shows that the leakage current increases exponentially with increasing negative measurement voltage; while the difference between the curves shows that the leakage current gradually decreases with increasing microwave processing time.

[0036] from Figure 4 The results show that microwave treatment can effectively reduce the leakage current of ferroelectric capacitors after voltage cycling; as the microwave treatment time increases, the leakage current of ferroelectric capacitors after voltage cycling gradually decreases.

[0037] Compared with the prior art, the positive effects of the present invention are: (1) First, the present invention addresses the existing methods for reducing leakage current of ferroelectric capacitors: improving the quality of ferroelectric capacitors through process optimization during the preparation process; however, the leakage current of ferroelectric capacitors made by this method will still increase after operation; redistributing oxygen vacancies through low voltage; however, new defects will still be generated under low voltage, reducing reliability; the method in the present invention innovatively proposes to redistribute oxygen vacancies by microwave control, which can reduce leakage current after the leakage current has increased, and will not generate new defects, effectively reducing leakage current and preventing breakdown.

[0038] (2) Secondly, in the method of the present invention, as the microwave processing time is extended, the leakage current of the ferroelectric capacitor after voltage cycling gradually decreases.

[0039] The above description only illustrates the preferred technical solution of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof all reflect the principles of the present invention and should be within the technical scope of the present invention.

Claims

1. A method for improving reliability by reducing leakage current of HZO ferroelectric capacitance through microwave processing, characterized in that, After detecting an increase in leakage current of the HZO ferroelectric capacitor, the following method is used to reduce the leakage current of the HZO ferroelectric capacitor, the method including the following steps: Step 1: Apply a cyclic voltage of a certain voltage and frequency to the HZO ferroelectric capacitor; Step 2: After applying the cyclic voltage, perform microwave processing for a certain period of time, power and frequency; The voltage amplitude of the cyclic voltage is ±2V to ±3V; The frequency of the cyclic voltage is 1 kHz to 100 kHz.

2. The method for reducing leakage current of HZO ferroelectric capacitors and improving reliability through microwave processing as described in claim 1, characterized in that, The HZO ferroelectric capacitor comprises a substrate material layer, a bottom metal layer, an HZO layer, and a top metal layer stacked sequentially, wherein the thickness of the HZO layer is 6-12 nm.

3. The method for reducing leakage current of HZO ferroelectric capacitors and improving reliability through microwave processing as described in claim 2, characterized in that, The substrate material layer is an N-type heavily doped substrate, made of Si or Ge, with a thickness of 700-800 μm.

4. The method for reducing leakage current of HZO ferroelectric capacitors and improving reliability through microwave processing as described in claim 3, characterized in that, The bottom metal layer and the top metal layer are made of the same material, which is TiN or W. The thickness of the bottom metal layer is 30-60 nm, and the thickness of the top metal layer is 30-60 nm.

5. The method for reducing leakage current of HZO ferroelectric capacitors and improving reliability through microwave processing as described in claim 4, characterized in that, The microwave processing time is 120s to 600s.

6. The method for reducing leakage current of HZO ferroelectric capacitors and improving reliability through microwave processing as described in claim 5, characterized in that, The power of the microwave processing is 400W to 1800W.

7. The method for reducing leakage current of HZO ferroelectric capacitors and improving reliability through microwave processing as described in claim 6, characterized in that, The frequency of the microwave processing is 1000MHz to 2000MHz.

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