Method for manufacturing gate oxide film
The multi-stage PEALD process with varying energy levels and high-temperature annealing addresses interface defects in gate oxide film manufacturing, improving film quality and device reliability by reducing leakage current and enhancing breakdown voltage.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- PROASIA SEMICONDUCTOR CORP
- Filing Date
- 2025-08-29
- Publication Date
- 2026-06-04
AI Technical Summary
Conventional gate oxide film manufacturing methods, such as high-temperature thermal oxidation, result in interface defects and carbon residues, leading to increased leakage current and reduced breakdown voltage capability, which degrades device reliability and switching speed.
A multi-stage oxygen plasma-enhanced atomic layer deposition (PEALD) process with varying energy levels is employed to form multiple silicon dioxide layers, followed by high-temperature annealing with nitric oxide or nitrous oxide, to reduce defects and enhance film quality.
The method improves the uniformity and electrical properties of the gate oxide film, reducing leakage current and enhancing the breakdown voltage and thermal stability of semiconductor devices.
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Figure 2026091797000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a gate oxide film, and particularly to a method for manufacturing a gate oxide film with reduced interface defect density.
Background Art
[0002] A gate oxide film is an important component in a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) and a High Electron Mobility Transistor (HEMT). Silicon dioxide (SiO2) is a commonly used gate oxide film material. This material is an insulating material. This insulating material functions as a dielectric layer, enabling the gate electric field to penetrate and control the carrier concentration in the semiconductor channel.
[0003] The quality, thickness, and dielectric constant of the gate oxide film directly affect the electrical characteristics of semiconductor devices, such as threshold voltage, on-current, and leakage current. With the reduction of device size, the requirements for the thin film quality of the gate oxide film are increasing day by day. In addition, the gate oxide film of conventional transistor devices is usually manufactured by a furnace tube high-temperature oxidation method. This process consumes a silicon-containing substrate (such as a silicon carbide substrate), causing roughness at the interface between the silicon-containing substrate and silicon dioxide, the generation of interface defects (Dit), and carbon residues. These problems increase the leakage current and reduce the switching speed. If the above problems exist for a long time, the breakdown voltage capability of the gate oxide film will decrease, resulting in device aging and reliability degradation. Therefore, improving the thin film quality of the gate oxide film is an urgent issue that needs to be solved in the current semiconductor industry.
Summary of the Invention
[0004] The main objective of the present invention is to provide a method for manufacturing high-quality gate oxide films. This method employs multi-stage oxygen plasma-enhanced atomic layer deposition (PEALD) technology with stepwise energy to form multiple oxide films on a silicon-containing substrate. This technology reduces surface defects and carbon residues, improving the uniformity and electrical properties of the oxide film.
[0005] To achieve the above objective, the present invention provides a method for manufacturing a gate oxide film, comprising the following steps. First, a silicon-containing substrate is prepared. Next, a first silicon dioxide layer is formed by deposition using a first oxygen plasma to cover the silicon-containing substrate. Next, a second silicon dioxide layer is formed by deposition using a second oxygen plasma to cover the first silicon dioxide layer. Finally, the second silicon dioxide layer is subjected to bombardment using a third oxygen plasma.
[0006] In the manufacturing method of the embodiment of the present invention, the step of preparing a silicon-containing substrate is to prepare a silicon carbide substrate or a silicon substrate.
[0007] In the manufacturing method of the embodiment of the present invention, the step of performing deposition using a first oxygen plasma involves forming a first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) using 10 to 20 watts (W) of oxygen plasma enhanced atomic layer deposition to coat a silicon-containing substrate.
[0008] In the manufacturing method of the embodiment of the present invention, the step of performing deposition using a second oxygen plasma involves forming a second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) using 100 to 300 watts (W) of oxygen plasma enhanced atomic layer deposition to cover the first silicon dioxide layer.
[0009] In the manufacturing method of the embodiment of the present invention, the step of performing bombardment using a third oxygen plasma involves performing bombardment on the second silicon dioxide layer using an oxygen plasma of 1500 to 2000 watts (W) to improve the density of the second silicon dioxide layer.
[0010] In the manufacturing method of the embodiment of the present invention, the process includes a step of performing bombardment using a third oxygen plasma, followed by a step of performing high-temperature annealing.
[0011] In the manufacturing method of the embodiment of the present invention, the high-temperature annealing step is to perform high-temperature annealing with nitric oxide or nitrous oxide (N2O).
[0012] To achieve the above objective, the present invention provides a method for manufacturing a gate oxide film, comprising the following steps. First, a silicon carbide substrate is prepared. Next, a first silicon dioxide layer covering the silicon carbide substrate is formed using multi-stage oxygen plasma enhanced atomic layer deposition, and then a second silicon dioxide layer covering the first silicon dioxide layer is formed. Finally, the second silicon dioxide layer is subjected to bombardment using oxygen plasma.
[0013] In another embodiment of the present invention, the manufacturing method involves a multi-stage oxygen plasma enhanced atomic layer deposition step, which includes forming a first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) using oxygen plasma enhanced atomic layer deposition at 10 to 20 watts (W) to coat a silicon carbide substrate, and then forming a second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) to coat the first silicon dioxide layer using oxygen plasma enhanced atomic layer deposition at 100 to 300 watts (W).
[0014] In another embodiment of the present invention, the step of bombarding the second silicon dioxide layer using oxygen plasma is to bombard the second silicon dioxide layer using 1500 to 2000 watts (W) of oxygen plasma to improve the density of the second silicon dioxide layer.
[0015] In another embodiment of the present invention, the manufacturing method includes a step of bombarding the second silicon dioxide layer using oxygen plasma, followed by a step of high-temperature annealing with nitric oxide or nitrous oxide (N2O).
[0016] Those skilled in the art will be able to understand other objects of the present invention, as well as the technical means and embodiments of the present invention, by referring to the drawings and the embodiments described later. [Brief explanation of the drawing]
[0017] [Figure 1] Schematic diagram of the gate oxide film produced in the embodiment of the present invention. [Figure 2] Flowchart of the manufacturing process for the gate oxide film of the present invention [Modes for carrying out the invention]
[0018] The present invention will be described below through examples. These examples illustrate the embodiments of the present invention and are not intended to limit the invention to any particular environment, application, or specific configuration described therein. Therefore, while the examples illustrate the present invention, they do not limit it. Components not directly related to the present invention are omitted and not shown in the embodiments and drawings. The dimensional relationships of the components in the drawings are for ease of understanding and do not limit the actual dimensions.
[0019] Figure 1 is a schematic diagram of a gate oxide film manufactured in an embodiment of the present invention, specifically illustrating the process for manufacturing a gate oxide film for a transistor device. Furthermore, in the following embodiments and drawings, elements not directly related to the present invention have been omitted for ease of understanding. Specifically, first, a silicon-containing substrate is prepared. The silicon-containing substrate is a silicon substrate or a silicon carbide substrate, but is not limited to these. The present invention will be described below using silicon carbide substrate 1 as an example.
[0020] Unlike conventional gate oxide film manufacturing techniques using high-temperature thermal oxidation, this invention utilizes a deposition method to form an oxide thin film. Specifically, this invention uses oxygen plasma-enhanced atomic layer deposition (PEALD) technology to form a gate oxide thin film on a silicon carbide substrate 1 through a multi-step process with stepwise energy. As shown in Figure 1, in the first step, low-power (10-20 watts (W)) oxygen plasma-enhanced atomic layer deposition (PEALD) is performed to precisely control and form a thin film with nanoscale thickness. For example, in this step, a first silicon dioxide layer 10 with a thickness of 10-20 angstroms (Å) is formed to cover the surface of the silicon carbide substrate 1.
[0021] Unlike conventional high-temperature thermal oxidation thin film growth, PEALD, employed in the first stage, deposits oxides at lower power and in a lower temperature environment. This method utilizes plasma to generate highly active ions and free radicals, providing additional energy necessary for the deposition reaction, accelerating the chemical reaction, and reducing the need for substrate heating. Furthermore, the PEALD process temperature in the first stage is lower than that of conventional thermal oxidation processes, reducing physical damage to the silicon carbide substrate surface during the deposition process and decreasing the defect density at the interface between the silicon carbide substrate and the gate oxide film.
[0022] As shown in Figure 1, the second stage of oxide film deposition is then carried out. This stage also uses an oxygen plasma deposition method to form the oxide film. Unlike the first stage, the second stage employs high-power plasma deposition, using, for example, a 100-300 watt (W) PEALD to form a second silicon dioxide layer 20 with a thickness of 400-500 angstroms (Å) that covers the first silicon dioxide layer 10. The reason for employing high power in the second stage is that the silicon carbide substrate 1 is already completely covered by the first silicon dioxide layer 10, and under the protection of the first silicon dioxide layer 10, no defects or carbon residue problems occur in the silicon carbide substrate 1. At this point, increasing the plasma energy enhances the reaction and accelerates the oxide film deposition rate until the second silicon dioxide layer 20 reaches a predetermined thickness.
[0023] Next, the second silicon dioxide layer 20 is bombarded using oxygen plasma to improve its density. Specifically, this process uses oxygen plasma with a power of 1500-2000 watts (W) or even higher, 3000-4000 watts, to bombard the second silicon dioxide layer 20. Oxygen molecules and free radicals from the high-energy plasma gas react with the second silicon dioxide layer 20, promoting further oxidation of the surface material, repairing defects at the intralayer and interlayer interfaces, and improving the density of the second silicon dioxide layer 20. This process improves the quality of the gate oxide film, enhances the electrical properties and reliability of the semiconductor device, and in particular reduces the leakage current of the device.
[0024] In a more preferred embodiment, high-temperature annealing is performed after the completion of oxygen plasma bombardment. High-temperature annealing is performed using nitric oxide or nitrous oxide (N2O) at a temperature range of 900°C to 1100°C. At high temperatures, N2O decomposes to produce active nitrogen oxides (NO, N2O, etc.), which effectively deactivate the interface between silicon and silicon dioxide, repair interface defects, and improve interface quality. Furthermore, nitrogen atoms generated by the decomposition of N2O during the high-temperature annealing process are incorporated into the gate oxide film, forming a silicon nitride (SiON) layer. This nitrogen-doped layer improves the field breakdown resistance of the oxide film, reduces leakage current, and enhances thermal stability.
[0025] Figure 2 is a flowchart of the manufacturing process for the gate oxide film of the present invention. First, a silicon-containing substrate is prepared in step S01. Next, in step S02, a first silicon dioxide layer is formed to cover the silicon-containing substrate by deposition using a low-power oxygen plasma. In step S03, a second silicon dioxide layer is formed to cover the first silicon dioxide layer by deposition using a high-power oxygen plasma. Finally, in step S04, the second silicon dioxide layer is subjected to bombardment treatment using an oxygen plasma to improve the density of the second silicon dioxide layer. The parameters of each related process have been explained in detail above and will not be repeated here.
[0026] The above embodiments illustrate the embodiments of the present invention and explain the characteristic configurations of the present invention. The present invention is not limited to the above embodiments. Modifications or equivalent arrangements that can be easily made by those skilled in the art are also within the scope of the present invention. The scope of protection of the rights of the present invention shall be based on the claims.
Description of Reference Numerals
[0027] 1 Silicon carbide substrate 10 First silicon dioxide layer 20 Second silicon dioxide layer S01 Process S02 Process S03 Process S04 Process
Claims
1. A method for manufacturing a gate oxide film, The process of preparing a silicon-containing substrate, A step of depositing using a first oxygen plasma to form a first silicon dioxide layer that covers the silicon-containing substrate, A step of depositing using a second oxygen plasma to form a second silicon dioxide layer that covers the first silicon dioxide layer, A method for manufacturing a gate oxide film, comprising the step of applying bombardment treatment to the second silicon dioxide layer using a third oxygen plasma.
2. The manufacturing method according to claim 1, characterized in that the step of preparing the silicon-containing substrate is to prepare a silicon carbide substrate or a silicon substrate.
3. The manufacturing method according to claim 1, characterized in that the step of performing deposition using a first oxygen plasma is to use 10 to 20 watts (W) of oxygen plasma-enhanced atomic layer deposition (PEALD) to form the first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) and cover the silicon-containing substrate.
4. The manufacturing method according to claim 1, characterized in that the step of performing deposition using a second oxygen plasma is to use 100 to 300 watts (W) of oxygen plasma-enhanced atomic layer deposition to form the second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) and cover the first silicon dioxide layer.
5. The manufacturing method according to claim 1, characterized in that the step of performing bombardment using a third oxygen plasma is to perform bombardment on the second silicon dioxide layer using an oxygen plasma of 1500 to 2000 watts (W) to improve the density of the second silicon dioxide layer.
6. The manufacturing method according to claim 1, characterized in that it includes a step of performing bombardment using a third oxygen plasma, followed by a step of performing high-temperature annealing.
7. The high-temperature annealing process involves nitric oxide or nitrous oxide (N) 2 The manufacturing method according to claim 6, characterized by performing a high-temperature annealing treatment in O).
8. A method for manufacturing a gate oxide film, The process of preparing a silicon carbide substrate, The process involves forming a first silicon dioxide layer covering the silicon carbide substrate using multi-stage oxygen plasma-enhanced atomic layer deposition (PEALD), and then forming a second silicon dioxide layer covering the first silicon dioxide layer. A method for manufacturing a gate oxide film, comprising the step of applying bombardment treatment to the second silicon dioxide layer using oxygen plasma.
9. The manufacturing method according to claim 8, characterized in that the multi-stage oxygen plasma enhanced atomic layer deposition step includes forming the first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) using oxygen plasma enhanced atomic layer deposition of 10 to 20 watts (W) to cover the silicon carbide substrate, and then forming the second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) to cover the first silicon dioxide layer using oxygen plasma enhanced atomic layer deposition of 100 to 300 watts (W).
10. The manufacturing method according to claim 8, characterized in that the step of applying bombardment treatment to the second silicon dioxide layer using oxygen plasma is to apply bombardment treatment to the second silicon dioxide layer using oxygen plasma of 1500 to 2000 watts (W) to improve the density of the second silicon dioxide layer.
11. After the step of bombarding the second silicon dioxide layer using oxygen plasma, further nitric oxide or nitrous oxide (N) is applied. 2 The manufacturing method according to claim 8, characterized in that it includes a step of performing a high-temperature annealing treatment in O).