Interface doping modification method of hafnium-based thin film dielectric material
Interface doping with elements like Si, Ge, Sn, Al, Ga, In, Mg, Ca, and Ba in hafnium-based thin films addresses leakage current issues in miniaturized devices by enhancing the Schottky barrier height and stabilizing charge distribution, thereby improving device reliability and performance.
Patent Information
- Application Number
- CN202510484654.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2025-07-11
AI Technical Summary
As electronic devices continue to shrink, hafnium-based thin films face significant leakage current issues due to the increased prominence of quantum tunneling effects, leading to reliability problems such as premature breakdown, despite existing methods like Al2O3 intermediate buffer layers and high-temperature oxygen annealing failing to adequately address the need for higher dielectric constants and lower leakage currents.
A method of interface doping is applied to the TiN/HfxZr1-xO2 interface in hafnium-based thin films, using elements like Si, Ge, Sn, Al, Ga, In, Mg, Ca, Sr, and Ba to form stable oxides, enhancing the Schottky barrier height and reducing leakage current while maintaining high dielectric constants.
The interface doping method effectively increases the Schottky barrier height, significantly reducing leakage current and improving the reliability and performance of electronic devices by stabilizing the interface charge distribution and reducing electron tunneling probabilities.
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Figure CN120302704A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of dielectric material modification, and particularly relates to an interface doping modification method for hafnium-based thin film dielectric materials. Background Art
[0002] As the size of electronic devices continues to shrink, silicon dioxide (SiO2, k = 4), as a traditional dielectric material, exhibits significant leakage characteristics due to the quantum tunneling effect. In contrast, hafnium-based thin films have been widely used in the industry due to their advantages such as low power consumption, high compatibility with CMOS processes, and good scalability. However, as the device size continues to shrink, the hafnium-based thin film has been reduced to 4 - 8 nm, and the leakage problem has become increasingly significant, causing reliability problems such as premature breakdown in practical applications. Therefore, how to reduce leakage is an important challenge faced by current hafnium-based thin films.
[0003] Research shows that the interface barrier between metals and high-k dielectric materials plays a key role in the generation of leakage current. Existing research has proposed methods to reduce leakage current, such as enhancing the interface barrier by introducing an Al2O3 intermediate buffer layer, which significantly reduces the leakage current. In addition, the heat treatment process is also an important technical means to reduce leakage current. By annealing in a high-temperature oxygen atmosphere, oxygen vacancies can be effectively repaired, the binding energy of cations at the interface can be increased, and the height difference of the Schottky barrier can be increased, thereby significantly reducing the leakage current. However, as the device size continues to shrink, the contradiction between further increasing the dielectric constant of the dielectric material and reducing the leakage current becomes more obvious. This technical bottleneck poses higher requirements for the leakage standards under continuous device scaling. Therefore, it is urgent to research and explore methods to achieve low leakage in the current system.
[0004] In summary, increasing the Schottky barrier helps to reduce leakage, and the size of the Schottky barrier is closely related to the charge transfer and charge redistribution at the interface. The interface dipole caused by interface charge transfer leads to charge redistribution, which can regulate the height of the Schottky barrier, and thus achieve a reduction in leakage current. Therefore, it is an urgent problem to be solved in the prior art to perform interface doping modification between hafnium-based thin films and metal electrodes in order to achieve lower leakage. Summary of the Invention
[0005] The purpose of the present invention is to provide an interface doping modification method for hafnium-based thin film dielectric materials. In an interface system with TiN as the metal electrode and Hf x Zr 1-x O2 as the dielectric film, by introducing an interface doping modification between TiN / Hf x Zr 1-xDope and modify the interface with doping elements. On the one hand, maintain the advantages of the HZO thin film in terms of high dielectric constant. On the other hand, significantly reduce the interface leakage current and improve the reliability and electrical performance of the device, so as to meet the requirements of next-generation small-size devices for low-leakage and high-performance interfaces.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] The present invention provides a method for interface doping modification of a hafnium-based thin film dielectric material, including: using TiN as the metal electrode and Hf x Zr 1-x O2 as the interface system of the dielectric thin film, and doping and modifying the interface of TiN / Hf x Zr 1-x O2 with doping elements; wherein:
[0008] The value range of x is 0-1;
[0009] The doping elements include:
[0010] (a) Elements with strong electronegativity, selected from one or more of Si, Ge, and Sn;
[0011] And / or (b) Metal elements that can form RO oxides with O elements in a ratio of 1:1, selected from one or more of Mg, Ca, Sr, and Ba;
[0012] And / or (c) Metal elements that can form R2O3 oxides with O elements in a ratio of 1:1.5, selected from one or more of Al, Ga, In, Sc, Y, and La.
[0013] Preferably, the thickness of the modified layer formed by doping the doping elements is 0.2-0.6 nm.
[0014] Preferably, x = 0.5.
[0015] Preferably, the doping elements are selected from one or more of Si, Ge, Sn, Al, Ga, In, Mg, Ca, Sr, and Ba.
[0016] More preferably, the doping element is Ca.
[0017] Preferably, using the TiN thin film as the metal layer and H x Z 1-x O2 dielectric thin film as the semiconductor layer, including the following steps:
[0018] (1) Deposit a TiN thin film on SiO2 by sputtering deposition to form a bottom electrode;
[0019] (2) Introduce doping elements, and use the ALD method between the TiN thin film and Hx Z 1-x Depositing doping materials at the interface of the O2 dielectric film to optimize the interface properties;
[0020] (3) Deposition of H by ALD x Z 1-x O2 dielectric film;
[0021] (4) In H x Z 1-x A TiN film is sputter-deposited on the O2 dielectric film as a top electrode, and a rapid thermal annealing process is performed to crystallize the film to complete the device structure.
[0022] Compared with the prior art, the present invention provides a method for modifying the interface of hafnium-based thin film dielectric materials by doping, wherein TiN is used as the metal layer, Hf x Zr 1-x O2 is a semiconductor layer, and elements are doped at its contact interface. x Zr 1-x A doping layer is deposited on an O2 substrate to form a thin film, and the doping layer is fully reacted with the interface through RTA treatment, the interface chemical environment is optimized, and the interface Schottky barrier is improved. Finally, a TiN film is deposited on the doped and modified interface by a sputtering deposition method to form a metal contact layer, thereby achieving interface doping modification. While maintaining the advantages of the HZO system in a small size, the present invention further improves the Schottky barrier through interface doping, reduces interface leakage current, enhances device reliability, and improves the overall performance of the device, thereby meeting the requirements of small-size devices for low leakage. Specifically, the present invention has the following beneficial effects:
[0023] (1) Based on the essential mechanism of interface doping regulation, doping a metal with high electronegativity at the metal / semiconductor interface can provide a portion of electrons to the interface system, increase the semiconductor band offset caused by the metal layer, increase the work function of the metal layer, thereby increasing the interface Schottky barrier and reducing the metal / semiconductor contact interface leakage current.
[0024] (2) By doping metal elements with a ratio of 1:1.5 and 1:1 to oxygen elements, these elements can form stable compounds with oxygen atoms on the interface, neutralize excess oxygen atoms on the interface, and reduce the concentration of oxygen vacancies on the interface. In this process, the metal adsorbs oxygen atoms to increase the charge redistribution on the interface, further increasing the Schottky barrier height on the interface and reducing the tunneling probability of electrons from the TiN electrode to the HZO ferroelectric layer, thereby effectively reducing the interface leakage current.
[0025] (3) The present invention reduces the leakage current of the TiN / HZO system through interface doping. First, through theoretical calculations and actual material screening, elements such as Si, Ge, Sn, Al, Ga, In, Mg, Ca, Sr, and Ba are selected for interface doping to increase the Schottky barrier and reduce the interface leakage current. Among them, elements with relatively large electronegativity, such as Si, Ge, and Sn, can significantly increase the Schottky barrier of the metal layer and raise the interface barrier height. Elements such as Al, Ga, In, Sc, Y, La with an oxygen element ratio of 1:1.5, and Mg, Ca, Sr, and Ba elements with an oxygen element ratio of 1:1 further optimize the interface chemical environment by neutralizing the interface oxygen. Combining calculations and experimental verification, Ca, as the optimal doping element, forms a stable compound with oxygen atoms, significantly increasing the Schottky barrier height at the TiN / HZO interface and showing more excellent leakage current suppression effect and interface stability. Description of the Drawings
[0026] Figure 1 It is a schematic diagram of the interface doping modification of the hafnium-based thin film dielectric material in the embodiment. 1 is the metal layer TiN; 2 is the semiconductor layer H x Z 1-x O2; 3 is the doping element layer.
[0027] Figure 2 It is a schematic diagram of the comparison of the Schottky barrier height in the method for reducing interface leakage in the embodiment. The ordinate is the Schottky barrier height, with the unit of eV. The dashed line is the Schottky barrier height of the undoped system. Detailed Embodiments
[0028] In order to more fully understand and demonstrate the technical solutions, objectives, and advantages of the present invention, the technical effects produced by the present invention will be further described in detail and completely below in combination with specific embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. It should be noted that for those of ordinary skill in the art, other embodiments obtained without departing from the concept of the present invention all belong to the protection scope of the present invention.
[0029] The calculation method used in the following embodiments is the first-principles calculation based on density functional theory, and the calculation software package used is the PWmat calculation software package, but it is not limited to this. There are also VASP, CASTEP, Gaussian, Wien2k, etc. The PWmat software is a first-principles calculation software package accelerated by GPU and provides most of the elements in the periodic table, with strong practicability.
[0030] Example 1
[0031] According to the interface doping modification structure of the hafnium-based thin film dielectric material as shown in Figure 1 In this embodiment, the metal layer is TiN and the semiconductor layer is Hf0.5 Zr 0.5 O2(HZO), the doping element for providing electrons is In, and the specific method is as follows:
[0032] Using the ALD method, a layer of In is deposited at the interface between TiN and HZO. The Schottky barrier height for In doping at the TiN / HZO interface is evaluated, and its barrier height is 1.47 eV, indicating that the barrier height is greater than the intrinsic TiN / HZO barrier height of 1.04 eV( Figure 2 ).
[0033] In this embodiment, using In as the metal / semiconductor interface doping element can increase the semiconductor band offset caused by the metal layer, and doping In at the TiN / HZO interface can significantly increase its Schottky barrier. The large Schottky barrier height confirms that interface doping with In can significantly reduce the leakage current at the TiN / HZO interface.
[0034] Example 2
[0035] In this embodiment, the metal layer is TiN and the semiconductor layer is HZO. The doping element for providing electrons is Ge, and the specific method is as follows:
[0036] Using the ALD method, a layer of Ge is deposited at the interface between TiN and HZO. The Schottky barrier height for Ge doping at the TiN / HZO interface is evaluated, and its barrier height is 1.42 eV, indicating that the barrier height is greater than the intrinsic TiN / HZO barrier height of 1.04 eV( Figure 2 ).
[0037] In this embodiment, using Ge as the metal / semiconductor interface doping element can increase the semiconductor band offset caused by the metal layer, and doping Ge at the TiN / HZO interface can significantly increase its Schottky barrier. The large Schottky barrier height confirms that interface doping with Ge can significantly reduce the leakage current at the TiN / HZO interface.
[0038] Example 3
[0039] In this embodiment, the metal layer is TiN and the semiconductor layer is HZO. The doping element for providing electrons is Ca, and the specific method is as follows:
[0040] Using the ALD method, a layer of Ca is deposited at the interface between TiN and HZO. The Schottky barrier height for Ca doping at the TiN / HZO interface is evaluated, and its barrier height is 2.09 eV, indicating that the barrier height is greater than the intrinsic TiN / HZO barrier height of 1.04 eV( Figure 2 ).
[0041] In this embodiment, Ca is used as the metal / semiconductor interface doping element, which can increase the semiconductor energy band offset caused by the metal layer. Moreover, doping Ca at the TiN / HZO interface can significantly increase its Schottky barrier. The large Schottky barrier height confirms that interface doping with Ca can significantly reduce the leakage current at the TiN / HZO interface.
[0042] Example 4
[0043] In this embodiment, the metal layer is TiN, the semiconductor layer is HZO, and the doping element for providing electrons is Sr. The specific method is as follows:
[0044] Using the ALD method, a layer of Sr is deposited at the interface between TiN and HZO. The Schottky barrier height for Sr doping at the TiN / HZO interface is evaluated, and its barrier height is 1.93 eV. The results show that the barrier height is greater than the barrier height of the intrinsic TiN / HZO, which is 1.04 eV ( Figure 2 ).
[0045] In this embodiment, Sr is used as the metal / semiconductor interface doping element, which can increase the semiconductor energy band offset caused by the metal layer. Moreover, doping Sr at the TiN / HZO interface can significantly increase its Schottky barrier. The large Schottky barrier height confirms that interface doping with Sr can significantly reduce the leakage current at the TiN / HZO interface.
[0046] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A method for interface doping modification of a hafnium-based thin film dielectric material, characterized in that, Including: Doping element doping modification is carried out on the interface system of the TiN metal electrode and the Hf x Zr 1-x O2 dielectric thin film; wherein: The numerical range of x is 0 - 1; The doping element includes: (a) Elements with strong electronegativity, selected from one or more of Si, Ge, and Sn; And / or (b) Metal elements that can form RO oxides with O element in a ratio of 1:1, selected from one or more of Mg, Ca, Sr, and Ba; And / or (c) Metal elements that can form R2O3 oxides with O element in a ratio of 1:1.5, selected from one or more of Al, Ga, In, Sc, Y, and La.
2. The interface doping modification method of the hafnium-based thin film dielectric material according to claim 1, wherein, The doping element is selected from one or more of Si, Ge, Sn, Al, Ga, In, Mg, Ca, Sr, and Ba.
3. The interface doping modification method of the hafnium-based thin film dielectric material according to claim 2, characterized in that, The doping element is Ca.
4. The method for interfacial doping modification of the hafnium-based thin film dielectric material according to claim 1, wherein The thickness of the modified layer formed by doping the doping element is 0.2 - 0.6 nm.
5. The method for interface doping modification of the hafnium-based thin film dielectric material according to claim 1, wherein x＝0.5。 6. The method for interface doping modification of the hafnium-based thin film dielectric material according to any one of claims 1 to 5, characterized in that, Using a TiN thin film as the metal layer and H x Z 1-x a ZrO2 dielectric thin film as the semiconductor layer, comprising the following steps: (1) Deposit a TiN thin film on SiO2 by sputtering deposition method to form a bottom electrode; (2) Introduce a doping element and deposit a doping material at the interface between the TiN film and the H x Z 1-x O2 dielectric film by ALD method to optimize the interface characteristics; (3) Deposit H by ALD method x Z 1-x O2 dielectric thin film; (4) On H x Z 1-x A TiN thin film is sputter-deposited as the top electrode on the HZO₂ dielectric thin film, and rapid thermal annealing treatment is carried out to crystallize the thin film.