Processing method of semiconductor structure

Abstract

The invention provides a semiconductor structure processing method, and the method comprises the steps: providing a semiconductor structure which comprises a substrate and an initial oxide layer formed on the substrate; placing the semiconductor structure in a processing chamber, and establishing a supercritical environment in the processing chamber to form a supercritical carbon dioxide fluid in the processing chamber; and introducing a cosolvent and a fluorine-containing reaction precursor into the processing chamber to generate hydrofluoric acid, and enabling the hydrofluoric acid to be adsorbed on the surface of the oxide layer by the supercritical carbon dioxide fluid so as to etch the initial oxide layer and form a target oxide layer with a rough surface, the roughness of the target oxide layer is greater than that of the initial oxide layer. According to the invention, the surface roughness of the target oxide layer can be controlled within an ideal range, and the target oxide layer with uniform roughness can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a processing method of semiconductor structure. BACKGROUND

[0002] In the manufacture of semiconductor devices, the rough surface of the oxide layer of the wafer can provide a larger specific surface area and mechanical interlocking effect, thereby significantly enhancing the adhesion of photoresist, metal or semiconductor film, preventing peeling and defect generation.

[0003] In the related art, the roughness of the surface of the oxide layer is mainly enhanced by wet chemical etching and plasma treatment. However, when the wet chemical etching is used to enhance the roughness of the surface of the oxide layer, it is difficult to accurately control the roughness, which is prone to cause excessive corrosion, poor uniformity, and collapse of the microstructure pattern and watermarks due to the surface tension of the liquid. When the plasma treatment is used, high-energy ions are prone to cause lattice damage and charge accumulation to the fragile oxide layer and the device below, and there is a depth-to-width ratio dependent effect in complex three-dimensional structures, and the roughness of the surface of the oxide layer after treatment is not uniform. SUMMARY

[0004] A series of simplified concepts are introduced in the summary section, which will be further described in detail in the detailed description section. The summary section of the present application does not mean to attempt to limit the key features and essential technical features of the claimed technical solutions, nor to determine the protection scope of the claimed technical solutions.

[0005] In view of the existing problems, the present application provides a processing method of semiconductor structure, which comprises: providing a semiconductor structure, which comprises a substrate and an initial oxide layer formed on the substrate; placing the semiconductor structure in a processing chamber, establishing a supercritical environment in the processing chamber to form a supercritical carbon dioxide fluid in the processing chamber; introducing a cosolvent and a fluorine-containing reaction precursor into the processing chamber to generate hydrofluoric acid, and the supercritical carbon dioxide fluid causes the hydrofluoric acid to be adsorbed on the surface of the initial oxide layer to etch the initial oxide layer and form a target oxide layer with a rough surface, wherein the roughness of the target oxide layer is greater than that of the initial oxide layer.

[0006] In one embodiment, the supercritical carbon dioxide fluid causes the hydrofluoric acid to be adsorbed on the surface of the initial oxide layer to etch the initial oxide layer and form a rough-surface oxide layer, comprising: the supercritical carbon dioxide fluid transports the hydrofluoric acid to the surface of the initial oxide layer; The hydrofluoric acid is adsorbed on the initial oxide layer and reacts with the initial oxide layer to etch the surface of the initial oxide layer; circulating the supercritical carbon dioxide fluid for a predetermined time period to form a uniform distribution of concave-convex topography on the surface of the initial oxide layer to form a target oxide layer with a rough surface.

[0007] In one embodiment, the predetermined time period ranges from 8 min to 15 min.

[0008] In one embodiment, establishing a supercritical environment in the processing chamber comprises: evacuating the processing chamber to have a pressure of the processing chamber less than 1 MPa; setting a temperature of the processing chamber to be no less than 31℃; introducing liquid carbon dioxide into the processing chamber and increasing a pressure of the processing chamber to be no less than 7.4 MPa to form a supercritical carbon dioxide fluid.

[0009] In one embodiment, after forming the target oxide layer with a rough surface, the processing method further comprises: stopping the introduction of the co-solvent and the fluorine-containing reactive precursor; cleaning the semiconductor structure by the supercritical carbon dioxide fluid; depressurizing the processing chamber to normal pressure and drying the semiconductor structure by the supercritical carbon dioxide.

[0010] In one embodiment, a speed of depressurizing the processing chamber is less than or equal to 100 psi / min.

[0011] In one embodiment, the fluorine-containing reactive precursor comprises nitrogen trifluoride or organic fluorides, and the co-solvent comprises methanol, ethanol or deionized water.

[0012] In one embodiment, a circulation pump is used to circulate the supercritical carbon dioxide fluid in the processing chamber.

[0013] In one embodiment, a processing temperature for processing the semiconductor structure ranges from 40℃ to 100℃, and a processing pressure ranges from 1000 psi to 5000 psi.

[0014] In one embodiment, a root mean square roughness of the target oxide layer ranges from 0.5 nm to 10 nm.

[0015] The semiconductor structure processing method of this application embodiment places the semiconductor structure in a supercritical environment in which supercritical carbon dioxide fluid is formed, and introduces a fluorine-containing reaction precursor and co-solvent into the supercritical carbon dioxide fluid to generate hydrofluoric acid. Through the molecular-level transport of supercritical carbon dioxide, the hydrofluoric acid is adsorbed on the surface of the initial oxide layer of the semiconductor structure, and the surface of the initial oxide layer is etched layer by layer from top to bottom to form a target oxide layer with a rough surface. The surface roughness of the target oxide layer can be controlled within an ideal range by precisely adjusting the parameters. Moreover, supercritical carbon dioxide has zero surface tension and a high diffusion coefficient, which can ensure that the surface roughness of all target oxide layers in the complex three-dimensional structure is consistent, so as to obtain a target oxide layer with uniform roughness. Attached Figure Description

[0016] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the invention and their descriptions to explain the principles of the invention.

[0017] In the attached image: Figure 1 A flowchart illustrating a semiconductor structure processing method according to a specific embodiment of this application is shown; Figure 2 A schematic diagram of the semiconductor structure before processing is shown using the semiconductor structure processing method according to a specific embodiment of this application. Figure 3 A schematic diagram of a semiconductor structure after processing using a semiconductor structure processing method according to a specific embodiment of this application is shown. Detailed Implementation

[0018] The present application will now be described more fully with reference to the accompanying drawings, in which embodiments of the present application are illustrated. However, the present application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0019] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0020] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0022] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms as defined in commonly used dictionaries shall be interpreted as having a meaning consistent with their meaning in the relevant field and / or the context of this specification, and not as in an ideal or overly formal sense, unless expressly defined herein.

[0023] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0024] In semiconductor device manufacturing, the rough oxide surface of a wafer provides a larger specific surface area and mechanical interlocking effect, thereby significantly enhancing adhesion to photoresist, metal, or semiconductor thin films and preventing peeling and defects.

[0025] In related technologies, wet chemical etching and plasma treatment are mainly used to enhance the surface roughness of oxide layers. Wet chemical etching uses diluted hydrofluoric acid to isotropically etch the oxide layer. However, this method is difficult to precisely control the roughness, easily leading to over-etching, poor uniformity, and, due to the surface tension of the liquid, can cause microstructure pattern collapse and watermarks. Plasma treatment, on the other hand, bombards the oxide layer surface with plasma through physical sputtering or chemical etching. High-energy ions can easily cause lattice damage and charge accumulation in the fragile oxide layer and the underlying devices. Furthermore, in complex three-dimensional structures, there is an aspect ratio-dependent effect, resulting in uneven surface roughness of the treated oxide layer.

[0026] Therefore, in view of the aforementioned technical problems, this application proposes a method for processing semiconductor structures, such as... Figure 1 As shown, it mainly includes the following steps: Step S110, providing a semiconductor structure, the semiconductor structure including a substrate and an initial oxide layer formed on the substrate; Step S120: Place the semiconductor structure in the processing chamber and establish a supercritical environment in the processing chamber to form a supercritical carbon dioxide fluid in the processing chamber; In step S130, a co-solvent and a fluorine-containing reaction precursor are introduced into the processing chamber to generate hydrofluoric acid. The supercritical carbon dioxide fluid causes the hydrofluoric acid to be adsorbed onto the surface of the oxide layer to etch the initial oxide layer and form a rough target oxide layer, wherein the roughness of the target oxide layer is greater than the roughness of the initial oxide layer.

[0027] The semiconductor structure processing method of this application embodiment places the semiconductor structure in a supercritical environment in which supercritical carbon dioxide fluid is formed, and introduces a fluorine-containing reaction precursor and co-solvent into the supercritical carbon dioxide fluid to generate hydrofluoric acid. Through the molecular-level transport of supercritical carbon dioxide, the hydrofluoric acid is adsorbed on the surface of the initial oxide layer of the semiconductor structure, and the surface of the initial oxide layer is etched layer by layer from top to bottom to form a target oxide layer with a rough surface. The surface roughness of the target oxide layer can be controlled within an ideal range by precisely adjusting the parameters. Moreover, supercritical carbon dioxide has zero surface tension and a high diffusion coefficient, which can ensure that the surface roughness of all target oxide layers in the complex three-dimensional structure is consistent, so as to obtain a target oxide layer with uniform roughness.

[0028] Below, for reference Figure 1 , Figure 2 and Figure 3 The processing method for the semiconductor structure in this application is described in detail, wherein, Figure 1 A flowchart illustrating a semiconductor structure processing method according to a specific embodiment of this application is shown; Figure 2 A schematic diagram of the semiconductor structure before processing is shown using the semiconductor structure processing method according to a specific embodiment of this application. Figure 3 A schematic diagram of a semiconductor structure after processing using a semiconductor structure processing method according to a specific embodiment of this application is shown.

[0029] For example, the semiconductor structure processing method of this application includes the following steps: First, such as Figure 1 As shown, step S110 is performed to provide a semiconductor structure, the semiconductor structure including a substrate and an initial oxide layer formed on the substrate.

[0030] For example, such as Figure 2 As shown, the semiconductor structure includes a substrate 200, on which an initial oxide layer 201 is formed. Exemplarily, the thickness of the initial oxide layer ranges from 50 nm to 200 nm, for example, the thickness of the initial oxide layer is 50 nm, 100 nm, 150 nm or 200 nm.

[0031] For example, the substrate 200 can be any suitable semiconductor substrate, such as a silicon substrate, or at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, including multilayer structures composed of these semiconductor materials, or silicon on insulator (SOI), silicon on insulator (SSOI), silicon on insulator (S-SiGeOI), silicon on insulator (SiGeOI), and germanium on insulator (GeOI), or it can be a double-side polished wafer (DSP), or a ceramic substrate such as alumina, a quartz or glass substrate, etc.

[0032] Then, continue as follows Figure 1 As shown, step S120 is performed, in which the semiconductor structure is placed in the processing chamber and a supercritical environment is established in the processing chamber to form a supercritical carbon dioxide fluid in the processing chamber.

[0033] For example, first, the semiconductor structure is placed in a high-pressure resistant processing chamber. Then, the processing chamber is sealed, a vacuum is drawn into the processing chamber to make the pressure of the processing chamber less than 1 MPa, and the processing chamber is heated to make the temperature of the processing chamber not less than 31°C, for example, the temperature of the processing chamber is 65°C. Next, liquid carbon dioxide is injected into the processing chamber, and the pressure of the processing chamber is increased to not less than 7.4 MPa, for example, the pressure is increased to 2500 psi, so that the processing chamber is in a supercritical environment, and the injected liquid carbon dioxide becomes a supercritical carbon dioxide fluid.

[0034] Then, continue as follows Figure 1 As shown, in step S130, a co-solvent and a fluorine-containing reaction precursor are introduced into the processing chamber to generate hydrofluoric acid. The supercritical carbon dioxide fluid causes the hydrofluoric acid to be adsorbed onto the surface of the oxide layer to etch the initial oxide layer and form a rough target oxide layer, wherein the roughness of the target oxide layer is greater than the roughness of the initial oxide layer.

[0035] For example, the fluorine-containing reaction precursor includes nitrogen trifluoride or an organofluorine compound, and the cosolvent includes methanol, ethanol or deionized water, wherein the organofluorine compound includes trifluoroacetic acid, trifluoroacetic anhydride or pyridine hydrogen fluoride.

[0036] In one example, 200 μL of deionized water and 500 μL of methanol are first injected into the processing chamber as a co-solvent. Simultaneously, nitrogen trifluoride gas is introduced into the chamber at a flow rate of 5 sccm. In a supercritical carbon dioxide environment, nitrogen trifluoride reacts with the co-solvent water to generate hydrofluoric acid in situ. The generated hydrofluoric acid is surrounded and transported by supercritical carbon dioxide molecules. The high diffusion coefficient of the supercritical carbon dioxide fluid allows the generated hydrofluoric acid to be distributed uniformly and rapidly throughout the chamber without resistance. Because the hydrofluoric acid is highly uniformly distributed throughout the fluid, it adsorbs onto the entire surface of the initial oxide layer and reacts chemically with it to selectively etchinate the initial oxide layer surface from top to bottom at the nanoscale, ultimately forming uniformly distributed nanoscale pits, thus creating a uniformly distributed uneven morphology. This etching process is a mild, selective chemical corrosion process, rather than high-energy physical bombardment, and therefore does not cause lattice damage or charge accumulation.

[0037] Environmental conditions can be kept constant, such as maintaining the temperature and pressure of the processing chamber. A circulation pump, such as a magnetically coupled gear pump or a centrifugal pump, is used to circulate supercritical carbon dioxide fluid within the processing chamber for a predetermined time, ranging from 8 to 15 minutes (e.g., 8, 10, or 15 minutes). This circulation aims to form uniformly distributed pits and protrusions on the surface of the initial oxide layer, thereby creating a layer that resembles... Figure 3 The target oxide layer 202 with a rough surface is shown. During the etching process, the volatile products (such as SiF4) and excess reactants generated by the etching reaction are rapidly dissolved in the supercritical carbon dioxide fluid and carried away by the circulating fluid, thus avoiding the redeposition of by-products on the surface of the structure.

[0038] It is worth mentioning that during circulation, supercritical carbon dioxide fluid serves as the transport medium. This fluid is a mixture of supercritical carbon dioxide, a co-solvent, a fluorine-containing reaction precursor, and in-situ generated hydrofluoric acid. The mixed fluid flows out of the processing chamber outlet, sequentially passing through a circulation pump, a filter / heat exchanger, and a static mixer, before finally returning to the processing chamber from the inlet. This forms a high-pressure, forced-flow loop that does not exchange with the external atmosphere, allowing for continuous operation for a predetermined duration. Supercritical carbon dioxide fluid possesses zero surface tension and a high diffusion coefficient, enabling it to instantly fill and penetrate every corner of any high aspect ratio structure, thus ensuring consistent surface roughness across all target oxide layers in complex three-dimensional structures.

[0039] In some examples, the processing temperature range for processing the semiconductor structure is 40°C to 100°C, for example, 40°C, 65°C, or 100°C, and the processing pressure range is 1000psi to 5000psi, for example, 1000psi, 2500psi, or 5000psi.

[0040] Next, the flow of co-solvent and fluorine-containing reaction precursor was stopped, and the semiconductor structure was cleaned with supercritical carbon dioxide fluid. Then, the pressure in the processing chamber was reduced to atmospheric pressure, and the semiconductor structure was dried by utilizing the surface tension-free property of supercritical carbon dioxide, thereby preserving the newly generated nanoscale rough structure.

[0041] In one example, after circulating supercritical carbon dioxide fluid for 10 minutes, the flow of the co-solvent and fluorine-containing reaction precursor into the processing chamber is stopped. The semiconductor structure is then rinsed with supercritical carbon dioxide fluid to remove residual fluorides and other contaminants. After rinsing, the processing chamber is depressurized to slowly reduce the pressure to atmospheric pressure, for example, at a rate of less than or equal to 100 psi / min. The semiconductor structure is dried using the surface tension-free properties of supercritical carbon dioxide fluid, thus preserving the rough target oxide layer intact. The semiconductor structure is then removed, and its roughness is tested. Roughness testing can be performed using an atomic force microscope or other suitable tools or methods, without limitation in this application. The test results show that the processing method of this application can control the root mean square roughness of the target oxide layer of the semiconductor structure within the range of 0.5nm-10nm. In one embodiment, after the semiconductor structure is processed by the processing method of this application, atomic force microscopy shows that the root mean square roughness of the oxide layer on the surface of the semiconductor structure increases from 0.2nm before processing to 2.5nm after processing. That is, the root mean square roughness of the initial oxide layer is 0.2nm, and the root mean square roughness of the target oxide layer is 2.5nm, and the distribution is uniform. Obviously, the processing method of this application can greatly enhance the roughness of the oxide layer on the substrate surface. In the process of forming the target oxide layer through cyclic processing and in the process of cleaning and drying the semiconductor structure after forming the target oxide layer, the co-solvent is dissolved in the mixed fluid. There are no water droplets, methanol droplets or other condensed solvent droplets that exist independently in liquid state throughout the process, avoiding the generation of liquid phase. This can fundamentally eliminate the capillary force that causes the collapse of fine patterns, thereby achieving structureless collapse.

[0042] This concludes the description of the key steps in the semiconductor structure processing method of this application. The complete semiconductor structure processing method may also include other steps, which will not be elaborated here. It is worth mentioning that the order of the above steps can be adjusted without conflict.

[0043] The semiconductor structure processing method of this application places the semiconductor structure in a supercritical environment containing supercritical carbon dioxide fluid, and introduces a fluorine-containing reaction precursor and co-solvent into the supercritical carbon dioxide fluid to generate hydrofluoric acid. Through molecular-level transport of supercritical carbon dioxide, the hydrofluoric acid is adsorbed onto the surface of the initial oxide layer of the semiconductor structure, and the surface of the initial oxide layer is etched layer by layer from top to bottom to form a rough target oxide layer. The surface roughness of the target oxide layer can be controlled within an ideal range by precisely adjusting the parameters. Furthermore, supercritical carbon dioxide has zero surface tension and a high diffusion coefficient, which can ensure that the surface roughness of all target oxide layers in the complex three-dimensional structure is consistent, so as to obtain a target oxide layer with uniform roughness. Moreover, the entire process is free from high-energy ion bombardment, avoiding damage to the dielectric strength and interface states of the oxide layer by plasma, thus achieving no physical damage. The processing method of this application avoids the generation of liquid phase throughout the entire process from reaction to drying, thereby avoiding capillary forces that would cause the collapse of fine patterns, and thus achieving no structure collapse.

[0044] Although several embodiments have been described herein, it should be understood that many other modifications and embodiments will arise in the mind of those skilled in the art, all of which will fall within the spirit and scope of the concept disclosed herein. More specifically, various modifications and changes may be made in terms of the arrangement and / or components of the subject matter within the scope of this disclosure, the drawings, and the appended claims. In addition to modifications and changes in the components and / or arrangement, the use of alternative methods will also be obvious to those skilled in the art.

Claims

1. A method for processing a semiconductor structure, characterized in that, The processing method includes: A semiconductor structure is provided, the semiconductor structure including a substrate and an initial oxide layer formed on the substrate; The semiconductor structure is placed in a processing chamber, and a supercritical environment is established in the processing chamber to form a supercritical carbon dioxide fluid in the processing chamber. A co-solvent and a fluorine-containing reactive precursor are introduced into the processing chamber to generate hydrofluoric acid. The supercritical carbon dioxide fluid causes the hydrofluoric acid to be adsorbed onto the surface of the initial oxide layer to etch the initial oxide layer and form a rough target oxide layer, wherein the roughness of the target oxide layer is greater than that of the initial oxide layer.

2. The processing method as described in claim 1, characterized in that, The supercritical carbon dioxide fluid causes the hydrofluoric acid to adsorb onto the surface of the initial oxide layer, thereby etching the initial oxide layer to form a rough oxide layer, including: The supercritical carbon dioxide fluid delivers the hydrofluoric acid to the surface of the initial oxide layer; The hydrofluoric acid is adsorbed onto the initial oxide layer and reacts with the initial oxide layer to etch the surface of the initial oxide layer. The supercritical carbon dioxide fluid is circulated for a predetermined time to form a uniformly distributed uneven morphology on the surface of the initial oxide layer, thereby forming a target oxide layer with a rough surface.

3. The processing method as described in claim 2, characterized in that, The scheduled duration is 8-15 minutes.

4. The processing method as described in claim 1, characterized in that, Establishing a supercritical environment in the processing chamber includes: The processing chamber is evacuated so that the pressure in the processing chamber is less than 1 MPa; The temperature of the processing chamber is set to be no less than 31°C; Liquid carbon dioxide is introduced into the processing chamber, and the pressure in the processing chamber is increased to not less than 7.4 MPa to form a supercritical carbon dioxide fluid.

5. The processing method as described in claim 1, characterized in that, After forming the target oxide layer with a rough surface, the process also includes: Stop introducing the co-solvent and the fluorine-containing reaction precursor; The semiconductor structure is cleaned using the supercritical carbon dioxide fluid; The pressure in the processing chamber is reduced to atmospheric pressure, and the semiconductor structure is dried using the supercritical carbon dioxide fluid.

6. The processing method as described in claim 5, characterized in that, The depressurization rate of the processing chamber is less than or equal to 100 psi / min.

7. The processing method as described in claim 1, characterized in that, The fluorine-containing reaction precursor includes nitrogen trifluoride or an organofluorine compound, and the cosolvent includes methanol, ethanol or deionized water.

8. The processing method as described in claim 1, characterized in that, A circulation pump is used to circulate the supercritical carbon dioxide fluid within the processing chamber.

9. The processing method as described in claim 1, characterized in that, The processing temperature range for processing the semiconductor structure is 40℃-100℃, and the processing pressure range is 1000psi-5000psi.

10. The processing method as described in claim 1, characterized in that, The root mean square roughness of the target oxide layer ranges from 0.5 nm to 10 nm.

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