Manufacturing method of gate oxide layer

Abstract

This invention provides a method for manufacturing a gate oxide layer, comprising the following steps: First, providing a silicon-containing substrate. Next, providing a first oxygen plasma deposition to form a first silicon dioxide layer covering the silicon-containing substrate. Second, providing a second oxygen plasma deposition to form a second silicon dioxide layer covering the first silicon dioxide layer. Finally, providing a third oxygen plasma to bombard the second silicon dioxide layer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a gate oxide layer, and more particularly to a method for manufacturing a gate oxide layer that reduces the density of interface defects. Prior Technology

[0002] Gate oxide is a crucial component in semiconductor devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and high-electron-mobility transistors (HEMTs). A common gate oxide material is silicon dioxide (SiO₂), whose main function is to insulate and control the gate voltage's influence on electron flow within the semiconductor channel.

[0003] The quality, thickness, and dielectric constant of the gate oxide layer directly affect the electrical performance of semiconductor devices, such as turn-on voltage, conduction current, and leakage current. As device dimensions continue to shrink, the requirements for the thin film quality of the gate oxide layer are becoming increasingly stringent. Furthermore, since the traditional process for fabricating gate oxide layers in transistor devices typically utilizes furnace tubes for high-temperature oxidation, this method not only consumes silicon-containing substrates (such as silicon carbide substrates) but also introduces problems such as rough interfaces between the silicon-containing substrate and silicon dioxide, interfacial defects (Dit), and carbon residue, thereby increasing leakage current and reducing switching speed. Over time, this leads to a decrease in the gate oxide layer's withstand voltage, resulting in device aging and reduced reliability. Therefore, improving the thin film quality of the gate oxide layer is a pressing issue for the industry. Summary of the Invention

[0004] The main objective of this invention is to provide a method for manufacturing high-quality gate oxide thin films. The method uses a stepped energy multi-stage oxygen plasma-assisted atomic layer deposition (PEALD) technique to form multiple oxide layers on a silicon-containing substrate, thereby reducing surface defects and carbon residues, and improving the uniformity and electrical performance of the oxide film.

[0005] To achieve the above objectives, the present invention provides a method for manufacturing a gate oxide layer, comprising the following steps: First, a silicon-containing substrate is provided. Next, a first oxygen plasma is deposited to form a first silicon dioxide layer covering the silicon-containing substrate. Second, a second oxygen plasma is deposited to form a second silicon dioxide layer covering the first silicon dioxide layer. Finally, a third oxygen plasma is provided to bombard the second silicon dioxide layer.

[0006] In one embodiment of the manufacturing method of the present invention, the step of providing a silicon-containing substrate involves providing one of a silicon carbide substrate and a silicon substrate.

[0007] In one embodiment of the manufacturing method of the present invention, the step of providing a first oxygen plasma deposition involves providing 10 to 20 watts (W) of oxygen plasma-assisted atomic layer deposition to form a first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) covering a silicon-containing substrate.

[0008] In one embodiment of the manufacturing method of the present invention, the step of providing a second oxygen plasma deposition involves providing 100 to 300 watts (W) of oxygen plasma-assisted atomic layer deposition to form a second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) covering the first silicon dioxide layer.

[0009] In one embodiment of the manufacturing method of the present invention, the step of providing a third oxygen plasma involves providing 1500 to 2000 watts (W) of oxygen plasma to bombard a second silicon dioxide layer, thereby increasing the density of the second silicon dioxide layer.

[0010] In one embodiment of the manufacturing method of the present invention, after the step of providing a third oxygen plasma, a step of providing a high-temperature tempering treatment is further included.

[0011] In one embodiment of the manufacturing method of the present invention, a high-temperature tempering step is provided by providing a high-temperature tempering treatment with nitrogen oxides or nitrous oxides (N₂O).

[0012] To achieve the above objectives, the present invention provides a method for manufacturing a gate oxide layer, comprising the following steps: First, a silicon carbide substrate is provided. Next, a multi-stage oxygen plasma-assisted atomic layer deposition is performed to form a first silicon dioxide layer covering the silicon carbide substrate, followed by the formation of a second silicon dioxide layer covering the first silicon dioxide layer. Finally, oxygen plasma is used to bombard the second silicon dioxide layer.

[0013] In another embodiment of the manufacturing method of the present invention, the step of providing multi-stage oxygen plasma-assisted atomic layer deposition includes providing 10 to 20 watts (W) of oxygen plasma-assisted atomic layer deposition to form a first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) covering a silicon carbide substrate, and then providing 100 to 300 watts (W) of oxygen plasma-assisted atomic layer deposition to form a second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) covering the first silicon dioxide layer.

[0014] In another embodiment of the manufacturing method of the present invention, the step of providing oxygen plasma to bombard the second silicon dioxide layer involves providing 1500 to 2000 watts (W) of oxygen plasma to bombard the second silicon dioxide layer, thereby increasing the density of the second silicon dioxide layer.

[0015] In another embodiment of the manufacturing method of the present invention, after the step of providing oxygen plasma to bombard the second silicon dioxide layer, a step of providing nitric oxide or nitrous oxide (N₂O) for high-temperature tempering is further included.

[0016] After referring to the drawings and the embodiments described below, those skilled in the art will understand other objects of the present invention, as well as the technical means and implementation of the present invention. Simple Explanation of the Diagram

[0017] Figure 1 is a schematic diagram of the fabrication of the gate oxide layer in one embodiment of the present invention; and Figure 2 is a schematic diagram of the process steps for fabricating the gate oxide layer of the present invention. Implementation

[0018] The present invention will be explained below through embodiments. These embodiments are not intended to limit the implementation of the invention to any specific environment, application, or special method as described in the embodiments. Therefore, the descriptions of the embodiments are for illustrative purposes only and are not intended to limit the invention. It should be noted that in the following embodiments and drawings, elements not directly related to the present invention have been omitted and are not shown, and the dimensional relationships between the elements in the drawings are for ease of understanding only and are not intended to limit the actual scale.

[0019] Please refer to Figure 1, which shows a schematic diagram of manufacturing a gate oxide layer according to an embodiment of the present invention, and more particularly a schematic diagram of manufacturing a gate oxide layer in a transistor device. It should be noted that in the following embodiments and figures, components not directly related to the present invention are omitted for ease of understanding. Specifically, as shown in Figure 1, a silicon-containing substrate is first provided. This silicon-containing substrate can be, but is not limited to, a silicon substrate or a silicon carbide substrate. The present invention will be specifically described below using a silicon carbide substrate 1 as an example.

[0020] Unlike traditional methods that use high-temperature thermal oxidation to fabricate gate oxide layers, this invention uses a deposition method to grow oxide films. Specifically, this invention employs plasma-enhanced atomic layer deposition (PEALD) technology to form gate oxide films on silicon carbide substrates 1 in a stepped, multi-stage manner. As shown in Figure 1, in the first stage, low-power plasma deposition is performed, for example, providing 10 to 20 watts (W) of PEALD to precisely control and form films with nanometer-level thicknesses. For example, a first silicon dioxide layer 10 with a thickness of 10 to 20 angstroms (Å) is formed to cover the silicon carbide substrate 1.

[0021] Compared to traditional high-temperature thermal oxidation film growth, the first stage employs the PEALD system, which deposits oxides at lower power and lower temperatures. This approach stems from the fact that plasma generates highly reactive ions and free radicals, providing additional energy for the deposition reaction, promoting chemical reactions, and reducing the need for substrate heating required in traditional processes. Furthermore, because the temperature in the first-stage PEALD process is lower than that of traditional thermal oxidation processes, it helps reduce physical damage to the silicon carbide substrate surface during deposition, thus contributing to a reduction in defect density at the interface between the traditional silicon carbide substrate and the gate oxide layer.

[0022] Please refer to Figure 1. Next, the second stage oxide layer deposition process is performed. In this stage, the oxide layer is also formed using oxygen plasma deposition. However, unlike the first stage, high-power plasma deposition is used in the second stage. For example, a PEALD of 100 to 300 watts (W) is provided to form a second silicon dioxide layer 20 with a thickness of 400 to 500 angstroms (Å) covering the first silicon dioxide layer 10. The reason for using high power in the second stage is that the silicon carbide substrate 1 is completely covered by a thin layer of the first silicon dioxide layer 10. Therefore, under the protection of the first silicon dioxide layer 10, there is no longer any concern about defect generation or carbon residue on the silicon carbide substrate 1. Thus, the plasma energy can be increased to promote enhanced reactivity and accelerate the deposition rate of the oxide layer until the second silicon dioxide layer 20 reaches the predetermined thickness.

[0023] Next, an oxygen plasma is provided to bombard the second silicon dioxide layer 20, thereby increasing its density. Specifically, an oxygen plasma of 1500 to 2000 watts (W), or even 3000 to 4000 watts, is provided to bombard the second silicon dioxide layer 20. The oxygen molecules and free radicals in the high-energy plasma gas can react with the second silicon dioxide layer 20, further oxidizing the surface material and repairing interface defects, thus increasing the density of the second silicon dioxide layer 20. This is crucial for improving the quality of the gate oxide layer and enhancing the electrical performance and reliability of semiconductor devices, such as reducing leakage current.

[0024] In a preferred embodiment, a high-temperature tempering process is performed after the oxygen plasma bombardment step. For example, nitrogen oxide or nitrous oxide (N₂O) is provided for high-temperature tempering in a temperature range of 900°C to 1100°C. By decomposing N₂O at high temperature to generate active nitrogen oxides (NO, N₂O, etc.), the interface between silicon and silicon dioxide is effectively passivated, defects at the interface are repaired, and the interface quality is improved. Furthermore, N₂O decomposes during the high-temperature tempering process to generate nitrogen atoms, which can be incorporated into the gate oxide layer to form a nitrogen-doped oxide layer (SiON). This nitrogen-doped layer can improve the oxide layer's resistance to electric field breakdown, reduce leakage current, and improve thermal stability.

[0025] Please refer to Figure 2, which shows a schematic diagram of the fabrication steps of the gate oxide layer of the present invention. First, in step S01, a silicon-containing substrate is provided. Second, in step S02, low-power oxygen plasma deposition is performed to form a first silicon dioxide layer covering the silicon-containing substrate. In step S03, high-power oxygen plasma deposition is performed to form a second silicon dioxide layer covering the first silicon dioxide layer. Finally, in step S04, a third oxygen plasma is provided to bombard the second silicon dioxide layer to increase its density. The relevant process parameters for each step are explained in the foregoing description and will not be repeated here.

[0026] The above embodiments are merely illustrative of the implementation of the present invention and to explain its technical features, and are not intended to limit the scope of protection of the present invention. Any changes or equivalent arrangements that can be easily made by those skilled in the art are within the scope of the present invention, and the scope of protection of the present invention shall be determined by the scope of the patent application.

[0027] 1: Silicon carbide substrate 10: First silicon dioxide layer 20: Second silicon dioxide layer S01: Steps S02: Steps S03: Steps S04: Steps

Claims

1. A method for manufacturing a gate oxide layer, comprising: providing a silicon-containing substrate; depositing a first oxygen plasma with a power of 10 to 20 watts (W) to form a first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) covering the silicon-containing substrate; depositing a second oxygen plasma with a power of 100 to 300 watts (W) to form a second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) covering the first silicon dioxide layer; and providing a third oxygen plasma to bombard the second silicon dioxide layer.

2. The manufacturing method as described in claim 1, wherein the step of providing a silicon-containing substrate comprises providing either a silicon carbide substrate or a silicon substrate.

3. The manufacturing method as claimed in claim 1, wherein the step of providing a third oxygen plasma involves providing 1500 to 2000 watts (W) of oxygen plasma to bombard the second silicon dioxide layer, thereby increasing the density of the second silicon dioxide layer.

4. The manufacturing method as described in claim 1 further includes a step of providing a high-temperature tempering treatment after the step of providing a third oxygen plasma.

5. The manufacturing method as described in claim 4, wherein the step of providing a high-temperature tempering treatment is a high-temperature tempering treatment of nitrogen oxides or nitrous oxides (N₂O).

6. A method for manufacturing a gate oxide layer, comprising: providing a silicon carbide substrate; providing multi-stage plasma-assisted atomic layer deposition (PEALD), first forming a first silicon dioxide layer at low power to cover the silicon carbide substrate, and then forming a second silicon dioxide layer at high power to cover the first silicon dioxide layer; and providing oxygen plasma to bombard the second silicon dioxide layer.

7. The manufacturing method as described in claim 6, wherein the step of providing multi-stage oxygen plasma-assisted atomic layer deposition comprises providing 10 to 20 watts (W) of oxygen plasma PEALD to form a first silicon dioxide layer with a thickness of 10 to 20 angstroms (Å) covering the silicon carbide substrate, and then providing 100 to 300 watts (W) of oxygen plasma PEALD to form a second silicon dioxide layer with a thickness of 400 to 500 angstroms (Å) covering the first silicon dioxide layer.

8. The manufacturing method as claimed in claim 6, wherein the step of providing oxygen plasma to bombard the second silicon dioxide layer comprises providing 1,500 to 2,000 watts (W) of oxygen plasma to bombard the second silicon dioxide layer, thereby increasing the density of the second silicon dioxide layer.

9. The manufacturing method as claimed in claim 6, wherein after the step of providing oxygen plasma to bombard the second silicon dioxide layer, a step of providing a high-temperature tempering treatment with nitric oxide or nitrous oxide (N₂O) is further included.

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