Method for improving interface quality of indium gallium oxide film in atomic layer deposition technology

Abstract

According to the method for improving the interface quality of the indium gallium oxide thin film in the atomic layer deposition technology, the migration rate of the IGO thin film transistor is remarkably improved by optimizing the proportion of the precursor in the initial cycle. A fixed cycle ratio (for example, In: Ga = 3: 1) is adopted for IGO deposition in a traditional experiment, and the problems of multiple interface defects and low carrier mobility exist. According to the method, the proportion of precursors is adjusted to be 13: 1 (for example, the ratio of In to Ga is 13: 1) in the first ALD cycle, the uniformity of the initial nucleation stage is enhanced, interface defects are reduced, and meanwhile the conventional proportion (3: 1) of subsequent cycles is maintained. Compared with the prior art, the IGO thin film prepared by the method has the advantages that the roughness is reduced by 22%, the transistor mobility is improved by about 56.7%, the process compatibility is high, additional equipment investment is not needed, and the method is suitable for manufacturing high-performance semiconductor devices.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor film preparation, and in particular to a method for improving the interface quality of an indium gallium oxide film in an atomic layer deposition technology. Background Art

[0002] Indium (In)-based oxides have achieved great success in display applications due to their excellent mobility, uniformity and superior optical transparency. Among them, indium oxide films exhibit high mobility and high electron density, which is due to the overlap of isotope-diffused In orbitals, providing effective electron permeation paths and high oxygen vacancy defects. However, this also leads to the inability to completely shut down the film channel and the instability of the device. Studies have shown that these problems of indium oxide can be effectively solved by doping with metal cations with higher oxygen aggregation energy. Among these cationic dopants, gallium (Ga) is considered to be a potent In due to its small radius, high ionic potential and high bonding energy with oxygen. 2 O 3 Binders and carrier inhibitors. Recently, oxides have received great attention as the next-generation channel materials for 3D DRAM, 3D NAND and M3D (Mirauge3D) due to their excellent performance to meet the growing demand for semiconductor chips under Moore's Law. For semiconductor applications, traditional physical vapor deposition (PVD) processes cannot meet the stringent requirements of 3D nanostructures, such as uniform coverage and thickness controllability of conformal deposition. The atomic layer deposition (ALD) technology, due to its unique self-limiting growth behavior, has good uniformity and precise thickness control, and can embed oxide films in complex three-dimensional device structures. For example, CN112877674A discloses a Sn-doped Ga with precisely controllable content. 2 O 3 A method for growing a film material, comprising the steps of: growing n 1 Ga 2 O 3 Thin film; growth of 1 cycle of SnO 2 Thin film; Growth 2 Ga 2 O 3 This step is repeated many times to obtain a Sn-doped Ga film of a predetermined thickness. 2 O 3 Thin film, Sn-doped Ga deposited by ALD 2 O 3 Thin film, realizing Sn element in Ga 2 O 3 Atomic-level doping in thin films.

[0003] However, the actual ALD deposition goes through a process from nucleation to film formation, which is not a self-limiting growth at the beginning, which leads to more film defects at the interface compared with the stable growth stage. Summary of the invention

[0004] The purpose of the present invention is to provide a method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology in order to solve the above problems. By adjusting the ratio of the first cycle, the problem of more film defects at the interface can be effectively solved. By adjusting the precursor ratio of the initial ALD cycle, the interface quality of indium gallium oxide (IGO) thin films can be improved and the mobility can be increased.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The purpose of the present invention is to provide a method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology, which is an atomic layer deposition (ALD) method for improving the interface quality and mobility of indium gallium oxide (IGO) thin films. The method comprises the following steps:

[0007] Step 1: Perform the first atomic layer deposition (ALD) macrocycle on the substrate surface, with the pulse number ratio of precursor A to precursor B being 13:1;

[0008] Step 2: Perform a subsequent atomic layer deposition cycle. In the subsequent atomic layer deposition (ALD) cycle, the pulse ratio of precursor A to precursor B is adjusted to 3:1.

[0009] Step 3: Repeat step 2 until the target film thickness is reached to complete the deposition of the indium gallium oxide film;

[0010] Precursor A is an indium source, and precursor B is a gallium source.

[0011] Furthermore, a large cycle refers to: N indium cycles (N=13 or 3) and one gallium cycle, which together constitute a large cycle.

[0012] Furthermore, the precursor A is dimethyl indium (DADI), and the precursor B is trimethyl gallium (TMGa).

[0013] Furthermore, in step one, the pulse number of precursor A is 13 times, the pulse number of precursor B is 1 time, and the single pulse time of precursor A is 0.1 second, the pulse interval of precursor A is 10 seconds, the single pulse time of precursor B is 0.05 second, and the pulse interval of precursor B is 10 seconds.

[0014] Furthermore, in step 2, the pulse number of precursor A is 3 times, the pulse number of precursor B is 1 time, and the single pulse time of precursor A is 0.1 second, the pulse interval of precursor A is 10 seconds, the single pulse time of precursor B is 0.05 second, and the pulse interval of precursor B is 10 seconds.

[0015] Furthermore, in step 1, the deposition temperature of the atomic layer deposition is 250° C., and the pressure of the reaction chamber is 0.1-10 Torr.

[0016] Furthermore, in step 2, the deposition temperature of the atomic layer deposition is 250° C., and the pressure of the reaction chamber is 0.1-10 Torr.

[0017] Furthermore, the substrate is a silicon wafer.

[0018] Furthermore, before the first atomic layer deposition macrocycle is performed on the substrate surface, the substrate is cleaned.

[0019] Furthermore, after the first large cycle of atomic layer deposition, the root mean square roughness of the interface is 0.8-1.0 nm.

[0020] Further preferably, after the first atomic layer deposition macrocycle, the root mean square roughness of the interface is 0.874 nm.

[0021] Furthermore, in step 3, the target film thickness is 10-20 nm, and after the deposition of the indium gallium oxide film is completed, the carrier mobility of the indium gallium oxide film is 21-24 cm 2 / (V·s).

[0022] Compared with the prior art, the present invention has the following characteristics:

[0023] 1) In the traditional ALD process, a fixed precursor ratio (such as In:Ga=3:1) easily leads to competitive adsorption of indium and gallium atoms in the initial nucleation stage, forming an uneven island growth structure, thereby causing interface defects (such as holes or grain boundary dislocations). The present invention adjusts the precursor ratio (In:Ga) of the first atomic layer deposition cycle to 13:1 (In:Ga), significantly increasing the pulse frequency ratio of indium atoms (such as 13 TMI pulses and 1 TMGa pulse), so that indium atoms preferentially cover the substrate surface to form a continuous and dense indium-enriched seed layer. This seed layer not only provides uniform nucleation sites for subsequent deposition, but also suppresses the random aggregation of gallium atoms by reducing the surface energy difference. Experiments show that the adjusted initial cycle can reduce the interface roughness (RMS) from 1.12nm in the traditional process to 0.874nm, a decrease of 22%. Atomic force microscopy (AFM) analysis shows that the optimized interface presents a highly smooth three-dimensional growth pattern, which effectively reduces the interface trap density of carrier scattering.

[0024] 2) The method of improving the interface quality of indium gallium oxide thin film in atomic layer deposition technology of the present invention directly improves the electrical properties of IGO thin film by optimizing the interface quality. The dense seed layer reduces the height of the grain boundary barrier. At the same time, the uniform indium distribution reduces the localized electron state density, which significantly enhances the continuity of the carrier migration path. The Hall effect test shows that after adopting the 13:1 / 3:1 cycle ratio of the present invention, the carrier mobility of IGO thin film increases from 10.3 cm / s in the traditional process to 10.5 cm / s in the conventional process. 2 / (V·s) increased to 23.84cm 2 / (V·s), an increase of 56.7%. This improvement is particularly important in high-frequency devices.

[0025] 2) The core advantage of the method of improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology of the present invention lies in its seamless compatibility with existing ALD production lines. There is no need to modify the hardware equipment to adjust the cycle ratio. Only the precursor pulse sequence parameters (such as the number of pulses and timing) need to be modified through software programming. The pulse control accuracy (±0.01 seconds) and temperature control stability (±1°C) of mainstream ALD equipment (such as Cambridge NanoTech Savannah series) fully support the cycle switching between 13:1 and 3:1. In actual verification, this method was used to continuously deposit 100 batches of IGO films on commercial ALD equipment, and the process repeatability deviation was less than 2% (mobility fluctuation range: 23.36~24.32cm 2 / (V·s)), and the equipment maintenance cycle is consistent with the traditional process. In addition, since there is no need to introduce new precursors or vacuum chamber modifications, the production cost only increases by about 1.5% (mainly due to fine-tuning of the indium source dosage), which is much lower than the 10% to 20% cost increase of other interface optimization technologies (such as plasma treatment or insertion layer deposition), making the present invention quickly applicable to large-scale mass production scenarios such as flexible display driver ICs and high-resolution OLED backplanes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagrams of ALD cycles of the present invention and conventional methods are compared, wherein (a): Comparative Example 1, (b): Example 1;

[0027] Figure 2 1 is a comparison curve of the film mobility of Example 1 and Comparative Example 1;

[0028] Figure 3 These are AFM morphology images of the interface, where (a) is comparative example 1, and (b) is example 1. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific embodiments, but is by no means intended to limit the present invention. Features such as preparation methods, materials, structures or composition ratios not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0030] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0031] In the following embodiments, atomic layer deposition is performed using ALD equipment, specifically Cambridge NanoTech Savannah series.

[0032] Example 1

[0033] like Figure 1 As shown, this embodiment provides a method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology, including the following steps:

[0034] 1. Use RCA standard cleaning process to clean the silicon wafer substrate, and place the cleaned silicon wafer substrate in the ALD reaction chamber;

[0035] 2. First cycle: The first ALD macrocycle was performed on the substrate surface, with the pulse ratio of precursor A (DADI) to precursor B (TMGa) being 13:1, with 13 TMI pulses (0.1 s / time, 10 s interval), followed by 1 TMGa pulse (0.05 s / time, 10 s interval);

[0036] 3. Subsequent cycles: Perform subsequent atomic layer deposition cycles. In the subsequent atomic layer deposition cycle, the pulse ratio of precursor A (DADI) and precursor B (TMGa) is adjusted to 3:1, and the pulse ratio of TMI and TMGa is adjusted to 3:1. TMI pulses 3 times (0.1 seconds / time, 10 seconds interval), and then TMGa pulses 1 time (0.05 seconds / time, 10 seconds interval), and repeat 74 times;

[0037] Deposition parameters for the first cycle and subsequent cycles: temperature 250°C, pressure 5 Torr, film thickness 15 nm; as shown in Table 1, Figure 2 , Figure 3 As shown, the test results: migration rate 23.89cm 2 / (V·s), interface RMS 0.87nm.

[0038] Comparative Example 1

[0039] like Figure 1As shown, this comparative example provides a method for improving the interface quality of indium gallium oxide thin films in a conventional atomic layer deposition technology. Compared with the embodiment, the difference lies in step 2, and the other steps are the same as those in embodiment 1. In this comparative example, step 2 is:

[0040] 2. First cycle: Traditional 3:1 fixed cycle ratio, pulses were performed under the same parameters, the pulse ratio of precursor A (DADI) to precursor B (TMGa) was 3:1, DADI pulsed 3 times (0.1 s / time, 10 s interval), and then TMGa pulsed 1 time (0.05 s / time, 10 s interval).

[0041] As shown in Table 1, Figure 2 , Figure 3 As shown, the test results: migration rate 10.8cm 2 / (V·s), interface RMS 1.18nm.

[0042] Table 1 Mobility and interface root mean square roughness (interface RMS) of Example 1 and Comparative Example 1.

[0043]

[0044] As shown in Table 1, in the traditional ALD process, the fixed precursor ratio In:Ga=3:1 is prone to competitive adsorption of indium and gallium atoms in the initial nucleation stage, forming an uneven island growth structure, thereby causing interface defects (such as holes or grain boundary dislocations). The present invention adjusts the precursor ratio (In:Ga) of the first atomic layer deposition large cycle to 13:1 (In:Ga), significantly increasing the pulse frequency ratio of indium atoms (such as 13 TMI pulses and 1 TMGa pulse), so that indium atoms preferentially cover the substrate surface to form a continuous and dense indium-enriched seed layer. This seed layer not only provides a uniform nucleation site for subsequent deposition, but also suppresses the random aggregation of gallium atoms by reducing the surface energy difference. Experiments show that the adjusted initial cycle can reduce the interface roughness (RMS) from 1.12nm in the traditional process to 0.874nm, a decrease of 22%. Atomic force microscopy (AFM) analysis shows that the optimized interface presents a highly smooth three-dimensional growth pattern, which effectively reduces the interface trap density of carrier scattering. The method of improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology of the present invention directly improves the electrical properties of IGO thin films by optimizing the interface quality. The dense seed layer reduces the height of the grain boundary barrier. At the same time, the uniform indium distribution reduces the localized electron state density, and significantly enhances the continuity of the carrier migration path. The Hall effect test shows that after adopting the 13:1 / 3:1 cycle ratio of the present invention, the carrier mobility of the IGO thin film is increased from 10.3 cm / s in the traditional process to 10.5 cm / s in the conventional process. 2 / (V·s) increased to 23.84cm 2 / (V·s), an increase of 56.7%.

[0045] The pulse control accuracy (±0.01 seconds) and temperature control stability (±1°C) of mainstream ALD equipment (such as Cambridge NanoTech Savannah series) fully support the 13:1 and 3:1 cycle switching. In actual verification, this method was used to continuously deposit 100 batches of IGO films on commercial ALD equipment, and the process repeatability deviation was less than 2% (mobility fluctuation range: 23.36~24.32cm 2 / (V·s)), and the equipment maintenance cycle is consistent with the traditional process. In addition, since there is no need to introduce new precursors or vacuum chamber modifications, the production cost only increases by about 1.5% (mainly due to fine-tuning of the indium source dosage), which is much lower than the 10% to 20% cost increase of other interface optimization technologies (such as plasma treatment or insertion layer deposition).

[0046] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology, characterized in that: The method comprises the following steps: Step 1: Perform the first atomic layer deposition cycle on the substrate surface, with the pulse ratio of precursor A to precursor B being 13:1; Step 2: Perform a subsequent atomic layer deposition cycle. In the subsequent atomic layer deposition cycle, the ratio of the pulse times of precursor A and precursor B is adjusted to 3:1; Step 3: Repeat step 2 until the target film thickness is reached to complete the deposition of the indium gallium oxide film; Precursor A is an indium source, and precursor B is a gallium source.

2. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: The precursor A is dimethyl indium, and the precursor B is trimethyl gallium.

3. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: In step 1, the pulse number of precursor A is 13 times, the pulse number of precursor B is 1 time, and the single pulse time of precursor A is 0.1 second, the pulse interval of precursor A is 10 seconds, the single pulse time of precursor B is 0.05 second, and the pulse interval of precursor B is 10 seconds.

4. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: In step 2, the pulse number of precursor A is 3 times, the pulse number of precursor B is 1 time, and the single pulse time of precursor A is 0.1 second, the pulse interval of precursor A is 10 seconds, the single pulse time of precursor B is 0.05 second, and the pulse interval of precursor B is 10 seconds.

5. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: In step 1, the deposition temperature of the atomic layer deposition is 250° C., and the pressure of the reaction chamber is 0.1-10 Torr.

6. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: In step 2, the deposition temperature of the atomic layer deposition is 250° C., and the pressure of the reaction chamber is 0.1-10 Torr.

7. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: The substrate is a silicon wafer.

8. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: Clean the substrate before the first ALD macrocycle is performed on the substrate surface.

9. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: After the first large cycle of atomic layer deposition, the RMS roughness of the interface was 0.8-1.0 nm.

10. The method for improving the interface quality of indium gallium oxide thin films in atomic layer deposition technology according to claim 1, characterized in that: In step 3, the target film thickness is 10-20 nm. After the deposition of the InGaO film, the carrier mobility of the InGaO film is 21-24 cm 2 / (V·s).

Images