Substrate processing method

Abstract

The present application relates to the technical field of semiconductor manufacturing, and discloses a substrate processing method. The processing method comprises: providing a substrate that is provided with a protrusion and a trench, wherein the surface of the protrusion is provided with a first oxide layer; wet etching the substrate to remove the first oxide layer; forming a second oxide layer on the substrate, wherein the thickness of the second oxide layer is less than the thickness of the first oxide layer; washing the substrate; and drying the substrate. In the present method, the first oxide layer is removed and the new second oxide layer is generated, so that the etching difficulty of removing the first oxide layer is greatly reduced, which can be implemented by, for example, prolonging the etching time, thereby overcoming strict requirements for etching parameters. In addition, compared with simple etching processing, by generating the new second oxide layer, the thickness of the second oxide layer can also be accurately controlled.

Description

Substrate processing methods Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and more specifically to a substrate processing method. Background Technology

[0002] In semiconductor manufacturing, with the increasing integration of devices, more and more substrates have high aspect ratio structures. During the drying process, these high aspect ratio structures are susceptible to capillary forces, leading to collapse or adhesion, severely impacting device performance and reliability. In the drying step, capillary forces originate from the surface tension of the liquid within tiny gaps, causing these high aspect ratio structures to collapse or adhere. To address this issue, existing technologies typically reduce the impact of capillary forces by optimizing the drying process or surface treatment techniques.

[0003] In the fabrication of high aspect ratio structures on substrates, a thick oxide layer often exists on the substrate surface. After wet removal, drying is required immediately following. Current methods intentionally leave a portion of the oxide layer during hydrofluoric acid removal to reduce the risk of collapse or adhesion of the high aspect ratio structure during subsequent drying. However, this method is highly sensitive to the concentration and time of the hydrofluoric acid etching; slight errors can lead to insufficient or excessive etching of the oxide layer, affecting the drying process. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a substrate processing method.

[0005] This application solves the above-mentioned technical problems through the following technical solution:

[0006] A substrate processing method, comprising:

[0007] A substrate having protrusions and trenches is provided, wherein the surface of the protrusions has a first oxide layer;

[0008] The substrate is wet-etched to remove the first oxide layer;

[0009] A second oxide layer is formed on the substrate, wherein the thickness of the second oxide layer is less than the thickness of the first oxide layer;

[0010] Clean the substrate;

[0011] The substrate is then dried.

[0012] The significant advantages of this application are as follows: This method removes the first oxide layer and regenerates the second oxide layer. Compared to methods that strictly control etching concentration and etching time to remove the oxide layer, the etching difficulty of removing the first oxide layer is greatly reduced, overcoming the stringent requirements on etching parameters. Furthermore, compared to simple etching, by regenerating the second oxide layer, the thickness of the second oxide layer can be precisely controlled.

[0013] Overview of the attached figures

[0014] Figure 1 is a flowchart of a substrate processing method according to an embodiment of this application;

[0015] Figure 2 is a schematic diagram of step S100 of a substrate processing method according to an embodiment of this application;

[0016] Figure 3 is a schematic diagram of step S200 of a substrate processing method according to an embodiment of this application;

[0017] Figure 4 is a schematic diagram of step S300 of a substrate processing method according to an embodiment of this application.

[0018] Preferred embodiments of this application

[0019] The present application is further illustrated below by way of embodiments, but this does not limit the present application to the scope of the embodiments.

[0020] [Correction 27.10.2025 according to Rule 91] As shown in FIG1, this application provides a substrate processing method. Referring to FIG1, FIG2, and FIG4, the substrate processing method of this embodiment includes:

[0021] S100, a substrate having a protrusion 620 and a trench 640 is provided, wherein the surface of the protrusion 620 has a first oxide layer 630;

[0022] S200, wet etching of the substrate to remove the first oxide layer 630;

[0023] S300, A second oxide layer 650 is formed on the substrate, wherein the thickness of the second oxide layer 650 is less than the thickness of the first oxide layer 630;

[0024] S400, cleaning the substrate;

[0025] S500, the substrate is dried.

[0026] This method reduces the stringent requirements on wet etching parameters. Existing methods require strict control of the etching concentration and time when removing the first oxide layer 630; otherwise, over- or under-etching of the first oxide layer 630 may occur, affecting subsequent processes, such as causing trench collapse or adhesion of the substrate during drying. Compared to methods that retain a portion of the first oxide layer 630 while strictly controlling the etching concentration and time, this method eliminates the need to retain any portion of the first oxide layer, significantly reducing the difficulty of completely removing it. This can be achieved by increasing the etching time, overcoming the stringent requirements on etching parameters. Compared to existing methods, this method does not rely on complex etching conditions, greatly improving the stability of the drying process and reducing product defects caused by improper etching. Furthermore, compared to simple etching, the method of regenerating the second oxide layer 650 allows for more precise control of its thickness.

[0027] The above method will be explained in detail below with specific examples:

[0028] As shown in Figure 2, in step S100, the substrate provided in this embodiment has a protrusion 620 and a trench 640. The protrusion 620 includes a first portion 621 and a barrier layer 622 located on top of the first portion 621. The first portion 621 is made of the same material as the substrate, and a first oxide layer 630 is disposed above the barrier layer 622. In some embodiments, the substrate is a silicon substrate, and the material of the first portion 621 is also silicon. The trench 640 has a high aspect ratio, the barrier layer 622 is SiN (silicon nitride), and the first oxide layer 630 is SiO2 (silicon dioxide). The materials of the barrier layer 622 and the first oxide layer 630 are not limited to these; the specific materials are determined by the preceding processes.

[0029] As shown in Figure 3, in step S200, the first oxide layer 630 is completely removed using HF (hydrofluoric acid), wherein the ratio of HF to water is 1:100. The barrier layer 622 reacts weakly with the diluted HF and is almost unaffected. HF can also remove particles from the trench 640. In some embodiments, the concentration of HF is not limited to this, as long as the concentration is sufficient to remove the first oxide layer 630 and does not easily etch the protrusion 620.

[0030] In some embodiments, the protrusion may not include a barrier layer, and the etching solution may be diluted HF or other etching solutions that can remove the first oxide layer 630 and do not easily etch the protrusion 620.

[0031] As shown in Figure 4, in step S300, H2O2 (hydrogen peroxide) is used for oxidation treatment to generate a second oxide layer 650. Specifically, the second oxide layer 650 is SiO2. The second oxide layer 650 is formed on the upper surface of the barrier layer 622 and within the trenches 640. During the drying process, the higher the trench 640, the greater the capillary force it experiences. Therefore, the second oxide layer 650 at the barrier layer 622 plays a major role in preventing the trenches from collapsing or sticking together during subsequent drying. The main purpose of this step is to form a silicon dioxide layer on the surface of the barrier layer 622. In this embodiment, the first oxide layer 630 and the second oxide layer 650 are made of the same material. In other embodiments, the materials of the first oxide layer 630 and the second oxide layer 650 may be different. In other embodiments, other processing solutions such as O3 or SPM (hydrogen peroxide aqueous solution) may also be used for oxidation treatment.

[0032] In step S400, DIW (deionized water) is used for cleaning to remove residues from the above treatment process, such as residual H2O2.

[0033] In some embodiments, step S500 specifically includes:

[0034] S510. Perform hydrophobic treatment on the substrate to make the hydrophobicity of the second oxide layer 650 greater than that of the protrusion 620.

[0035] S520, dry substrate.

[0036] In step S510, the hydrophobicity of the second oxide layer 650 is greatly improved by performing a hydrophobic treatment on the substrate. This increases the contact angle of the second oxide layer 650, which is inversely proportional to capillary force, thereby significantly reducing capillary force and preventing the trenches 640 from collapsing or sticking together during the substrate drying process. Specifically, after the second oxide layer 650 and the protrusions 620 are respectively treated with hydrophobicity, the hydrophobicity of the second oxide layer 650 is greater than that of the protrusions 620. In these embodiments, the formation of the second oxide layer 650, compared to the absence of the second oxide layer 650, can improve the hydrophobicity of the substrate and reduce the likelihood of the trenches 640 collapsing or sticking together during the substrate drying process.

[0037] In some embodiments, step S510 specifically includes:

[0038] S511. Replace the moisture on the substrate with a drying solution;

[0039] S512. Replace the dried pharmaceutical solution on the substrate with a hydrophobic agent;

[0040] S513, Use a dry chemical solution to replace the hydrophobic agent on the substrate.

[0041] This method effectively prevents direct contact between moisture and the hydrophobic agent by first replacing the moisture with a drying solution and then introducing a hydrophobic agent, ensuring the stability and effectiveness of the hydrophobic agent. The hydrophobic agent significantly increases the contact angle between the drying solution and the second oxide layer 650 on the substrate surface. Since the contact angle is inversely proportional to the capillary force, it significantly reduces the capillary force, preventing the collapse or adhesion of high aspect ratio structures. After replacing the hydrophobic agent, the surface of the second oxide layer 650 becomes more hydrophobic, thereby increasing the contact angle between the drying solution and the second oxide layer 650. This adjustment significantly reduces the capillary force of the drying solution on the trench 640 during the drying process, reducing the risk of collapse or adhesion.

[0042] If a hydrophobic agent comes into contact with moisture, its chemical properties will change, and it will lose its hydrophobic properties. Therefore, it is necessary to strictly control the storage conditions of hydrophobic agents to avoid contact with moisture, maintain the chemical stability and effectiveness of the hydrophobic agent, and ensure that it can exert the ideal hydrophobic effect when applied to the substrate surface.

[0043] Specifically, the drying solution uses IPA (isopropanol). The hydrophobic agent uses SMT solution, which can be selected based on the material of the second oxide layer, specifically a silicon-based hydrophobic agent or a metal-based hydrophobic agent. Silicon-based hydrophobic agents hydrophobize silicon or silicon-containing compounds. Metal-based hydrophobic agents hydrophobize metals or metal-containing compounds. In steps S400 and S500, the substrate remains rotated. During the replacement of the treatment solution (which includes solutions used in cleaning and drying processes, such as replacing DIW with IPA, or IPA with SMT, etc.), the substrate's rotation speed is reduced. Specifically, the rotation speed can be gradually reduced from 300-1000 RPM to 10 RPM before the replacement treatment solution is applied. This helps prevent liquid film rupture and maintains uniform liquid film coverage. If the liquid film on the substrate surface ruptures during the replacement treatment solution, it will lead to uneven liquid film coverage on the substrate surface, affecting the processing effect. By reducing the rotation speed, the instability caused by high-speed substrate rotation can be avoided. Furthermore, centrifugal force can be reduced, preventing the processing solution from draining too quickly and ensuring that new processing solution flows smoothly and evenly covers the substrate surface. This effectively prevents liquid film rupture, maintains the uniformity of the processing solution, and guarantees that the entire substrate surface receives consistent chemical action.

[0044] In some embodiments, the thickness of the second oxide layer 650 is less than or equal to 1 nm. This method, by regenerating the second oxide layer 650, makes it easier to control the thickness of the second oxide layer.

[0045] The second oxide layer, 650, with a thickness of 1 nm or less, is beneficial for reducing interface resistance and improving electrical performance. In subsequent semiconductor processes, a thicker oxide layer may create a large barrier for electrons, affecting the device's electrical performance. A thinner oxide layer (1 nm or less) helps improve current transmission efficiency, reduce power consumption, and enhance device performance. However, a thicker oxide layer may contain more surface defects or trap sites, which can cause instability in semiconductor devices, affecting their lifetime and long-term stability. A thinner oxide layer can reduce defect density, thereby improving device reliability and reducing the probability of adverse phenomena such as leakage current. A thinner oxide layer can reduce interactions with materials or process steps in subsequent processes. For example, in metallization or other stacking processes, a thicker oxide layer may affect deposition quality or cause process incompatibility. A thinner oxide layer is more compatible with subsequent deposition, etching, diffusion, and other processes, ensuring process stability and consistency. In some high-speed devices, a thicker oxide layer increases parasitic capacitance, limiting the device's operating speed. By controlling the oxide layer thickness to 1 nm or less, the influence of parasitic capacitance can be reduced, improving the switching speed and frequency response of the device, making it suitable for higher frequency applications.

[0046] While specific embodiments of this application have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this application, but all such changes and modifications fall within the scope of protection of this application.

Claims

1. A substrate processing method, characterized in that, include: A substrate having protrusions and trenches is provided, wherein the surface of the protrusions has a first oxide layer; The substrate is wet-etched to remove the first oxide layer; A second oxide layer is formed on the substrate, wherein the thickness of the second oxide layer is less than the thickness of the first oxide layer; Clean the substrate; The substrate is then dried.

2. The substrate processing method as described in claim 1, characterized in that, The drying process of the substrate includes: The substrate is subjected to hydrophobic treatment; The substrate is dried.

3. The substrate processing method as described in claim 2, characterized in that, The hydrophobic treatment of the substrate includes: The moisture on the substrate is replaced with a drying solution; The dried pharmaceutical solution on the substrate was replaced with a hydrophobic agent; The hydrophobic agent on the substrate is replaced with a drying solution.

4. The substrate processing method according to any one of claims 1-3, characterized in that, In the steps of cleaning the substrate and drying the substrate, the substrate is kept in a rotating state, and the rotation speed of the substrate is reduced when the treatment liquid is replaced.

5. The substrate processing method as described in claim 1, characterized in that, The thickness of the second oxide layer is less than or equal to 1 nm.

6. The substrate processing method as described in claim 1, characterized in that, The wet etching process uses HF as the processing solution.

7. The substrate processing method as described in claim 1, characterized in that, The processing solution used to form the second oxide layer on the substrate is any one of O3, H2O2, or SPM.

8. The substrate processing method as described in claim 1, characterized in that, The second oxide layer is silicon dioxide.

9. The substrate processing method as described in claim 1, characterized in that, The protrusion further includes a barrier layer, on which the first oxide layer or the second oxide layer is disposed.

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