Doping modification method of dielectric material interface

Abstract

The invention provides a doping modification method of a dielectric material, and belongs to the technical field of modification of dielectric materials. In an interface system of a metal electrode and a hafnium-based thin film, metal element doping modification with weak electronegativity is carried out on the interface under the hafnium-based thin film. According to the invention, TiN is used as a metal layer to form a metal electrode, HZO is used as a semiconductor layer, a doped element layer is deposited on a contact interface of the metal electrode, metal Ca with weak electronegativity is deposited on the metal electrode through an ALD method to serve as the doped element layer, the HZO semiconductor layer is deposited on the doped element layer, and the doped element layer and the interface are fully reacted through rapid thermal annealing treatment. And finally, depositing a TiN metal layer on the semiconductor layer by adopting a sputtering deposition method to form a top electrode, thereby realizing interface doping modification. While the advantage of a small size of a TiN / HZO interface system is maintained, the Schottky barrier is further improved through interface doping, and the leakage current is reduced, so that the overall performance of the device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of dielectric material modification, and in particular relates to an interface doping modification method for realizing low leakage current hafnium-based thin films. Background Art

[0002] As electronic devices continue to shrink in size, silicon dioxide (SiO 2 , κ=4) As a traditional dielectric material, it exhibits significant leakage characteristics due to the quantum tunneling effect. In contrast, high-k dielectric materials, hafnium-based films, are widely used in the industry due to their low power consumption, high compatibility with CMOS processes, and good scalability. However, as device size continues to shrink, hafnium-based films have been reduced to 4-8nm, 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 currently facing hafnium-based films.

[0003] The interfacial Schottky barrier between metal and high-k dielectric material plays a key role in the generation of leakage current. In existing studies, it has been proposed that high-temperature oxygen atmosphere annealing can effectively repair oxygen vacancies, increase the binding energy of cations at the interface, and increase the height difference of the Schottky barrier, thereby significantly reducing the leakage current. However, as the size of devices continues to shrink, the proportion of interfaces gradually increases. The above methods alone cannot improve the interface well, and the contradiction between further improving the dielectric constant of dielectric materials and reducing leakage current becomes increasingly obvious. This technical bottleneck puts higher requirements on the interface and doping engineering. Therefore, it is urgent to explore methods to reduce leakage at the current metal-semiconductor interface.

[0004] Increasing the Schottky barrier at the metal-semiconductor interface helps reduce leakage. The size of the Schottky barrier is closely related to the charge transfer and charge redistribution at the interface. The interface dipole caused by the interface charge transfer will lead to charge redistribution, so that the height of the Schottky barrier can be adjusted, thereby reducing the leakage current. Therefore, interfacial doping modification between the hafnium-based film and the metal electrode in order to achieve lower leakage is an urgent problem to be solved in the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a method for modifying the interface of a dielectric material by doping. x Zr 1-x O 2 In the interface system of dielectric film, by doping elements at the TiN / HZO interface, Hf x Zr 1-x O 2On the other hand, the film has the advantage of high dielectric constant, which can significantly reduce interface leakage current and improve device reliability, thus meeting the needs of next-generation small-size devices for low leakage and high-performance interfaces.

[0006] The technical solution of the present invention is as follows:

[0007] A method for modifying the interface of a dielectric material by doping, in an interface system of a metal electrode and a hafnium-based film, modifying the interface under the hafnium-based film by doping with a metal element having a weaker electronegativity, the specific steps comprising:

[0008] (1) Sputtering deposition method on SiO 2 Depositing a metal layer on the substrate to form a metal electrode;

[0009] (2) Using the atomic layer deposition (ALD) method, a layer of metal with weak electronegativity is deposited on the metal electrode as a doping element layer;

[0010] (3) depositing a hafnium-based film as a semiconductor layer on the doped element layer by an atomic layer deposition (ALD) method, and performing a rapid thermal annealing (RTA) process to crystallize the film;

[0011] (4) depositing a metal layer on the semiconductor layer by sputtering deposition to form a top electrode and complete the device structure;

[0012] The doped element layer in step (2) provides a portion of electrons for the interface system, thereby increasing the band offset of the semiconductor layer caused by the metal layer, increasing the work function of the metal layer, thereby increasing the interface Schottky barrier and reducing the interface leakage current between the metal layer and the semiconductor layer.

[0013] Furthermore, the interface system between the metal electrode and the hafnium-based film is TiN and Hf x Zr 1-x O 2 interface system, the material of the metal layer is TiN, and the material of the hafnium-based thin film is Hf 0.5 Zr 0.5 O 2 .

[0014] Furthermore, the metal material of the doping element layer is Ca.

[0015] Furthermore, the thickness of the doped element layer is controlled to be 0.2-0.6 nm.

[0016] Furthermore, the annealing temperature of the rapid thermal annealing is controlled at 400-700°C.

[0017] The technical effects of the present invention are as follows:

[0018] The invention discloses a method for modifying the interface of a dielectric material by doping. Based on the essential mechanism of interface doping regulation, a layer of metal with weak electronegativity is deposited at the interface between a metal layer and a semiconductor layer as a doping element layer, which can provide a part of electrons for the interface system, increase the energy band offset of the semiconductor layer caused by the metal layer, increase the work function of the metal layer, thereby increasing the interface Schottky barrier and reducing the interface leakage current between the metal layer and the semiconductor layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of doping modification of the dielectric material interface in an embodiment of the present invention; 1 is a TiN metal layer; 2 is a HZO semiconductor layer; 3 is a Ca doped element layer;

[0020] Figure 2 Schematic diagram of comparison of Schottky barrier heights in the method for reducing interface leakage in an embodiment of the present invention; the ordinate is the Schottky barrier height in eV, where intrinsic is the Schottky barrier height in an undoped system. DETAILED DESCRIPTION

[0021] The present invention will be further clearly and completely described below through specific embodiments in conjunction with the accompanying drawings.

[0022] The calculation method used in the following embodiments is a first-principles calculation based on density functional theory, and the calculation software package used is the PWmat calculation software package, but is not limited to this, and there are also VASP, CASTEP, Gauss, Wien2k, etc. PWmat software is a first-principles calculation software package based on GPU acceleration, and it also provides most elements in the periodic table, and is highly practical.

[0023] The present invention provides a method for modifying the interface of a dielectric material by doping. Figure 1 The schematic diagram of the doping modification of the dielectric material interface obtained by this method, wherein 1 is a TiN metal layer, 2 is a HZO semiconductor layer, and 3 is a Ca doped element layer; a layer of metal Ca is deposited at the interface between TiN and HZO, and the specific method is as follows:

[0024] (1) Sputtering deposition method on SiO 2 A TiN metal layer is deposited on the substrate to form a metal electrode;

[0025] (2) using an atomic layer deposition (ALD) method to deposit a metal Ca doped element layer on the metal electrode, wherein the thickness of Ca is controlled to be 0.2-0.6 nm;

[0026] (3) depositing a HZO film as a semiconductor layer on the doped element layer by an atomic layer deposition (ALD) method, and performing a rapid thermal annealing (RTA) process to crystallize the film, wherein the annealing temperature is controlled at 400-700° C.;

[0027] (4) A TiN metal layer is deposited on the HZO semiconductor layer by sputtering deposition to form a top electrode, thereby completing the device structure.

[0028] Among them, HZO thin film material is Hf 0.5 Zr 0.5 O 2 .

[0029] The Schottky barrier height of the metal Ca doped at the TiN / HZO interface in this embodiment was evaluated and found to be 2.09 eV. The results showed that the barrier height was greater than the barrier height of the intrinsic TiN / HZO, 1.04 eV. Figure 2 shown.

[0030] In this embodiment, metal Ca is used as the doping element at the interface between the metal layer and the semiconductor layer, which can increase the band offset of the semiconductor layer caused by the metal layer, and metal Ca doping at the TiN / HZO interface can significantly increase its Schottky barrier. The large Schottky barrier height proves that interface doping with metal Ca can significantly reduce TiN / HZO interface leakage.

[0031] Finally, it should be noted that the purpose of publishing the embodiments is to help further understand the present invention, but those skilled in the art can understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A method for modifying the interface of a dielectric material by doping, characterized in that: In the interface system of the metal electrode and the hafnium-based film, the interface is modified by doping a metal element with weak electronegativity under the hafnium-based film. The specific steps include: (1) depositing a metal layer on SiO2 by a sputtering deposition method to form a metal electrode; (2) Using the atomic layer deposition (ALD) method, a layer of metal with weak electronegativity is deposited on the metal electrode as a doping element layer; (3) depositing a hafnium-based film as a semiconductor layer on the doped element layer by an atomic layer deposition (ALD) method, and performing a rapid thermal annealing (RTA) process to crystallize the film; (4) depositing a metal layer on the semiconductor layer by sputtering deposition to form a top electrode and complete the device structure; The doped element layer in step (2) provides a portion of electrons for the interface system, thereby increasing the band offset of the semiconductor layer caused by the metal layer, increasing the work function of the metal layer, thereby increasing the interface Schottky barrier and reducing the interface leakage current between the metal layer and the semiconductor layer.

2. The method for modifying the interface of a dielectric material according to claim 1, characterized in that: The interface system between the metal electrode and the hafnium-based film is TiN and Hf x Zr 1-x O2 interface system, the material of the metal layer is TiN, and the material of the hafnium-based thin film is Hf 0.5 Zr 0.5 O2.

3. The method for modifying the interface of a dielectric material according to claim 1, characterized in that: The metal material of the doping element layer is Ca.

4. The method for modifying the interface of a dielectric material according to claim 1, characterized in that: The thickness of the doped element layer is controlled at 0.2-0.6 nm.

5. The method for modifying the interface of a dielectric material according to claim 1, characterized in that: The annealing temperature of the rapid thermal annealing is controlled at 400-700°C.

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