A semiconductor substrate etching method

Abstract

The application relates to a semiconductor substrate etching method, which comprises the following steps: S100, providing a substrate to be etched; S200, first-stage etching, the etching gas is Cl-based gas and C / F compound gas, the flow rate of the C / F compound gas accounts for 15-30% of the flow rate of the Cl-based gas; S300, second-stage etching, the etching gas is Cl-based gas; wherein the first-stage etching time accounts for 20-80% of the total etching time; the by-product generated by the semiconductor substrate etching method is closely adhered to the top and / or sidewall of the etching chamber, after multiple batches of etching, the by-product is in a multilayer rod shape, and the number of layers of the by-product is positively correlated with the etching batches.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a semiconductor substrate etching method. Background Art

[0002] In the field of semiconductor manufacturing, plasma etching is generally a common technical route in the industry. In the LED industry chain, plasma etching is usually used in the patterned sapphire substrate etching process. Mass production involves multiple batches of etching. After a certain period of time, the etching chamber needs to be opened to clean the by-products produced by etching on the top and side walls. Otherwise, the amount of etching by-products will gradually increase over time and will inevitably fall off due to loose adhesion. Moreover, during batch operations, local etching by-products often fall off and fall onto the wafer due to loose adhesion, causing serious contamination and damage to the wafer pattern, which is not conducive to the stability of mass production and requires frequent opening of the etching chamber for maintenance. Summary of the Invention

[0003] In view of the above analysis, an embodiment of the present invention aims to provide a semiconductor substrate etching method, which can at least be used to solve one of the above problems.

[0004] The present invention provides a semiconductor substrate etching method, comprising the following steps:

[0005] S100: providing a substrate to be etched;

[0006] S200: first stage etching, the etching gas is Cl-based gas and C / F compound gas, and the flow rate of C / F compound gas accounts for 15% to 30% of the flow rate of Cl-based gas;

[0007] S300: back-end etching, the etching gas is Cl-based gas;

[0008] Among them, the first etching time accounts for 20% to 80% of the total etching time;

[0009] The byproducts generated by the semiconductor substrate etching method are tightly adhered to the top and / or sidewalls of the etching chamber. After multiple batches of etching, the byproducts are in the form of multi-layer rods, and the number of layers of the byproducts is positively correlated with the etching batches.

[0010] Furthermore, the compactness of the by-product is evaluated by the thickness of the by-product monolayer, and the thickness of the by-product monolayer is 1.35 to 2.5 μm.

[0011] Furthermore, in step S200: the upper radio frequency power is 1000-2000W, the lower radio frequency power is 200-1000W, and the temperature is -40-40°C.

[0012] Furthermore, the flow rate of the Cl-based gas is in the range of 60 to 150 sccm, and the flow rate of the C / F compound gas is in the range of 9 to 45 sccm.

[0013] Furthermore, in step S300: the upper radio frequency power is 1000-2000W, the lower radio frequency power is 100-1000W, and the temperature is -40-40°C.

[0014] Furthermore, the flow rate of the Cl-based gas is in the range of 60 to 150 sccm.

[0015] Further, the Cl-based gas is one of Cl2, BCl3, SiCl4, CCl4, and HCl;

[0016] The C / F compound gas is one of CHF3, CF4, C2F6, C3F8, C4F8, NF3, and CH2F2.

[0017] Furthermore, in step S100, the substrate is a sapphire substrate, and the method for preparing the sapphire substrate to be etched includes the following steps:

[0018] S101: Cleaning the sapphire flat sheet;

[0019] S102: coating photoresist on one side of the sapphire flat sheet, and then forming photoresist columns through pattern transfer technology to obtain a sapphire substrate to be etched.

[0020] Furthermore, in step S101, a mixed solution of sulfuric acid and hydrogen peroxide is used for cleaning, wherein the volume ratio of the sulfuric acid to the hydrogen peroxide is 3 to 6:1, the concentration of the sulfuric acid is 98.3%, and the concentration of the hydrogen peroxide is 30%.

[0021] Furthermore, the thickness of the coated photoresist is 0.2-5 μm.

[0022] Compared to existing technologies, the present invention achieves at least one beneficial effect: the semiconductor substrate etching method of the present invention effectively controls the compactness and adhesion of etching byproducts, improves the drop of byproducts in the chamber during the etching process, and virtually eliminates any drop of byproducts during the etching process, thereby extending the operating time of a single cycle and improving the throughput of plasma etching batch operations. The present invention can extend a single cycle to 200-260 hours, with a single cycle comprising 350-400 etching batches. This represents a 1-1.3-fold increase in the cycle time and etching times compared to existing conventional semiconductor substrate etching methods.

[0023] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0025] Figure 1 This is a SEM image of by-products when the first etching time accounts for less than 20% of the total etching time in a specific embodiment;

[0026] Figure 2 This is a SEM image of the by-product when the first etching time accounts for 20% of the total etching time in a specific embodiment;

[0027] Figure 3 This is a SEM image of the by-product when the first etching time accounts for 60% of the total etching time in a specific embodiment;

[0028] Figure 4 This is a SEM image of the by-product when the first etching time accounts for 80% of the total etching time in a specific embodiment;

[0029] Figure 5 This is a SEM image of by-products when the first etching time accounts for more than 80% of the total etching time in a specific embodiment;

[0030] Figure 6 A microscopic image of a by-product formed by the etching method of the present invention in a specific embodiment;

[0031] Figure 7 This is a SEM image of a by-product formed by the etching method of the present invention in a specific embodiment;

[0032] Figure 8 for Figure 7 Microscope images at different magnifications;

[0033] Figure 9 The SEM images of by-products of etching batch 360 at different magnifications in a specific embodiment are shown;

[0034] Figure 10 The SEM images of by-products of 90 etching batches at different magnifications in a specific embodiment are shown;

[0035] Figure 11 This is an SEM image of a patterned substrate obtained as an example in a specific embodiment;

[0036] Figure 12 The following are SEM images and elemental analysis diagrams of by-products produced in examples of specific embodiments. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0038] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the term "connected" should be understood in a broad sense. For example, it can mean a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection, an electrical connection, a direct connection, or an indirect connection through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] The terms "top," "bottom," "above," "below," and "on" used throughout the description refer to relative positions of components of a device, such as the relative positions of top and bottom substrates within a device. It will be understood that devices are multifunctional regardless of their orientation in space.

[0040] The working surface of the present invention can be a plane or a curved surface, can be inclined, or can be horizontal. For the convenience of description, the embodiment of the present invention is placed on a horizontal surface and used on the horizontal surface, and "high and low" and "up and down" are defined in this way.

[0041] A specific embodiment of the present invention discloses a semiconductor substrate etching method, which can be used at least for etching a sapphire substrate, and in particular for etching a patterned sapphire substrate.

[0042] The semiconductor substrate etching method comprises the following steps:

[0043] S100: providing a substrate to be etched;

[0044] S200: first stage etching, the etching gas is Cl-based gas and C / F compound gas, and the flow rate of C / F compound gas accounts for 15% to 30% of the flow rate of Cl-based gas;

[0045] S300: back-end etching, the etching gas is Cl-based gas;

[0046] Among them, the first etching time accounts for 20% to 80% of the total etching time;

[0047] The by-product produced by the semiconductor substrate etching method closely adheres to the top and / or sidewall of the etching chamber, and after multiple batches of etching, the by-product has a multi-layer rod shape, and the number of layers of the by-product is positively correlated with the number of etching batches.

[0048] The present application evaluates the compactness of the by-product by the single-layer thickness of the by-product, and the smaller the single-layer thickness, the higher the compactness, and the larger the single-layer thickness, the lower the compactness.

[0049] The number of layers of the by-product is the same as the number of etching batches.

[0050] It should be noted that a plurality of substrates can be processed in one etching, and the number of substrates depends on the size of the etching chamber and the size of the substrate.

[0051] The semiconductor substrate etching method of the present application can effectively control the compactness and adhesion of the etching by-product, improve the falling of the by-product in the etching process, almost avoid the falling of the by-product in the etching process, prolong the operation time of a cycle (the cycle refers to the cleaning cycle of the etching chamber), and improve the production capacity of the plasma etching batch operation.

[0052] Preferably, when the first etching time accounts for 55% of the total etching time, the by-product is best controlled, and the single-layer thickness of the by-product is about 1.5 μm.

[0053] In the step S100, the substrate is a sapphire substrate, and the preparation method of the sapphire substrate to be etched comprises the following steps:

[0054] S101: cleaning the sapphire flat sheet;

[0055] S102: coating photoresist on one side surface of the sapphire flat sheet, and then forming photoresist columns by pattern transfer technology to obtain the sapphire substrate to be etched.

[0056] In the step S101, a mixed solution of sulfuric acid and hydrogen peroxide is used for cleaning, the volume ratio of sulfuric acid to hydrogen peroxide is 3-6:1, the concentration of sulfuric acid is 98.3%, and the concentration of hydrogen peroxide is 30%.

[0057] In the step S102, the thickness of the coated photoresist is 0.2-5 μm. The pattern transfer technology can be exposure and development, or nano-imprinting. The photoresist column arrangement can be periodic arrangement (square lattice arrangement, hexagonal close-packed arrangement), or aperiodic quasi-crystal arrangement, or random arrangement.

[0058] The area ratio of the bottom surface of all photoresist columns to the single surface of the sapphire is 0.4-0.8.

[0059] In the step S200:

[0060] The upper RF power is 1000-2000W, the lower RF power is 200-1000W, and the temperature is -40-40°C.

[0061] The Cl-based gas is a main etching gas, which can be one of Cl2, BCl3, SiCl4, CCl4, and HCl.

[0062] The C / F compound gas is one of CHF3, CF4, C2F6, C3F8, C4F8, NF3, and CH2F2.

[0063] The flow rate of the Cl-based gas is in the range of 60 to 150 sccm, and the flow rate of the C / F compound gas is in the range of 9 to 45 sccm, that is, the flow rate of the C / F compound gas accounts for 15% to 30% of the flow rate of the Cl-based gas.

[0064] C / F compound gases significantly influence the shape and structure of etch byproducts, primarily due to differences in their composition and structure. Specifically, C / F compound gases directly affect the F content of these byproducts. Increasing the F content alters the molecular structure of these byproducts, significantly increasing their degree of aggregation and transforming their previously loose structure into a compact one.

[0065] In step S300:

[0066] The upper RF power is 1000~2000W, the lower RF power is 100~1000W, and the temperature is set to -40~40℃.

[0067] The Cl-based gas may be one of Cl2, BCl3, SiCl4, CCl4, and HCl.

[0068] The Cl-based gas flow rate range is 60 to 150 sccm.

[0069] It should be noted that the first etching time accounts for 20% to 80% (inclusive) of the total etching time. If it is less than 20% or more than 80%, the by-products will be too loose or too dense, which is not conducive to adhering to the top and side walls of the chamber and will easily fall off. For example, when the first etching time accounts for less than 20% of the total etching time (for example, 10%), the thickness of the single layer of by-products is thick (about 3.17) and loose, such as Figure 1 As shown in FIG; when the first etching time accounts for 20% of the total etching time, the thickness of the single layer of by-product is thin (about 2.44 μm) and relatively dense, as shown in FIG. Figure 2 As shown in FIG; when the first etching time accounts for 60% of the total etching time, the thickness of the single layer of by-product is thin (about 1.44 μm) and dense, as shown in FIG. Figure 3As shown; when the first etching time accounts for 80% of the total etching time, the thickness of the single layer of by-product is thin (about 1.35μm) and dense, as shown Figure 4 When the first etching time accounts for more than 80% of the total etching time (exemplarily 95%), the thickness of the single layer of by-products is too thin (1.13 μm) and too dense, as shown in FIG. Figure 5 shown.

[0070] The thickness of the by-product decreases with the increase of the proportion of the first etching time (the percentage of the first etching time in the total etching time), that is, the thickness of the by-product decreases with the increase of the first etching time, that is, when the first etching time accounts for 20% to 80% of the total etching time, the thickness of the by-product ranges from 1.35 to 2.5 μm.

[0071] The by-products formed by the etching method of the present invention adhere to the top and / or sidewalls of the etching chamber. After multiple batches of etching, the by-products are in the form of rods and gather together in the same direction. The microscopy of a single rod-shaped by-product (such as Figure 6 and Figure 7 shown) and SEM (as Figure 8 As shown in FIG, a uniform layer arrangement can be seen, and the number of layers is consistent with the number of etching batches, that is, one layer is added after each etching. Figure 9 As shown, the number of etching batches is 360 times, the total length of the by-product is 513 μm, the thickness of the single layer is 1.44 μm, and the thickness of the single layer multiplied by the number of batches is close to the total length; Figure 8 As shown, the number of etching batches is 90 times, the total length of the by-product is 150 μm, the thickness of the single layer is 1.63 μm, and the thickness of the single layer multiplied by the number of batches is close to the total length.

[0072] The semiconductor substrate etching method of the present invention can produce a patterned substrate and form a raised microstructure on the substrate surface. The raised microstructure can be conical, quasi-conical, quasi-truncated cone, quasi-polygonal cone, or quasi-polygonal cone. The ratio of the base width to the height of the raised microstructure is 0.3 to 0.8.

[0073] [Example] The semiconductor substrate etching method of the present invention comprises the following steps:

[0074] S100: providing a sapphire substrate to be etched;

[0075] S200: first etching, etching gases are BCl3 and CHF3, the gas flow rate of CHF3 is 20 sccm, the gas flow rate of BCl3 is 90 sccm, the upper RF power is 1400 W, the lower RF power is 800 W, the temperature is 24 ° C, and the etching time is 1100 s;

[0076] S300: back-end etching, the etching gas is BCl3, the gas flow of BCl3 is 80sccm, the upper RF power is 1400W, the lower RF power is 700W, the temperature is 24°C, and the etching time is 900s.

[0077] The patterned sapphire substrate is obtained by the method of the present invention, such as Figure 11 As shown in FIG, a conical convex microstructure is formed on the substrate surface, with a bottom width of 2.71 μm and a height of 1.79 μm. The by-products generated by the above method are tightly adhered to the top and / or sidewalls of the etching chamber. After multiple batches of etching, the morphology of the by-products is as follows: Figure 12 As shown, the monolayer thickness of the by-product is 1.44 μm. Figure 12 The elemental analysis of the byproducts shows that the F atomic ratio in the byproducts obtained by the present method can reach 22%, while the F atomic ratio in conventional etching methods is close to 0%. This shows that the present method can increase the F atomic ratio in the byproducts and change the composition and morphology of the byproducts. The cleaning cycle of the example is 200-260 hours, and 350-400 etching batches can be performed in one cleaning cycle.

[0078] The present invention can form a preset pattern substrate while improving the adhesion of by-products, greatly reducing the probability of by-products falling in the chamber during the etching process, and at the same time extending the operating time of a cycle.

[0079] By adjusting the etching steps, the present invention can effectively improve the dropout of byproducts and reduce the frequency of chamber cleaning. If byproducts drop prematurely before the predetermined period is reached, the etching method of the present invention can also improve the adhesion of the byproducts, reducing the frequency of premature chamber opening for cleaning.

[0080] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A semiconductor substrate etching method, characterized in that: The following steps are involved: S100: providing a substrate to be etched; S200: First stage etching, the etching gas is Cl-based gas and C / F compound gas, and the flow rate of C / F compound gas accounts for 15%~30% of the flow rate of Cl-based gas; S300: back-end etching, the etching gas is Cl-based gas; Among them, the first etching time accounts for 20%~80% of the total etching time; The byproducts generated by the semiconductor substrate etching method are tightly adhered to the top and / or sidewalls of the etching chamber. After multiple etching batches, the byproducts are in the form of multi-layer rods, and the number of layers of the byproducts is positively correlated with the etching batches. In step S200 , the upper RF power is 1000-2000 W, the lower RF power is 200-1000 W, and the temperature is -40-40° C.

2. The semiconductor substrate etching method according to claim 1, wherein: The compactness of the by-product is evaluated by the thickness of the by-product monolayer, which is 1.35-2.5 μm.

3. The semiconductor substrate etching method according to claim 1, wherein: The flow rate of the Cl-based gas is in the range of 60 to 150 sccm, and the flow rate of the C / F compound gas is in the range of 9 to 45 sccm.

4. The semiconductor substrate etching method according to claim 1, wherein: In step S300 , the upper RF power is 1000-2000 W, the lower RF power is 100-1000 W, and the temperature is -40-40° C.

5. The semiconductor substrate etching method according to claim 4, wherein: The flow rate of the Cl-based gas is in the range of 60 to 150 sccm.

6. The semiconductor substrate etching method according to claim 1, wherein: The Cl-based gas is one of Cl2, BCl3, SiCl4, CCl4, and HCl; The C / F compound gas is one of CHF3, CF4, C2F6, C3F8, C4F8, NF3, and CH2F2.

7. The semiconductor substrate etching method according to any one of claims 1 to 6, characterized in that: In step S100, the substrate is a sapphire substrate, and the method for preparing the sapphire substrate to be etched includes the following steps: S101: Cleaning the sapphire flat sheet; S102: coating photoresist on one side of the sapphire flat sheet, and then forming photoresist columns through pattern transfer technology to obtain a sapphire substrate to be etched.

8. The semiconductor substrate etching method according to claim 7, wherein: In step S101, a mixed solution of sulfuric acid and hydrogen peroxide is used for cleaning, wherein the volume ratio of sulfuric acid to hydrogen peroxide is 3-6:1, the concentration of sulfuric acid is 98.3%, and the concentration of hydrogen peroxide is 30%.

9. The semiconductor substrate etching method according to claim 7, wherein: The thickness of the coated photoresist is 0.2~5μm.

Images