Semiconductor substrate etching method

Abstract

The invention relates to a semiconductor substrate etching method. The method comprises the following steps: S100, providing a substrate to be etched; s200, first-section etching is conducted, etching gas is Cl-based gas and C / F compound gas, and the flow of the C / F compound gas accounts for 15%-30% of the flow of the Cl-based gas; s300, back-section etching is carried out, and the etching gas is Cl-based gas; wherein the first-section etching time accounts for 20%-80% of the total etching time; the by-product generated by the semiconductor substrate etching method is tightly adhered to the top or / and the side wall of an etching chamber, after multiple batches of etching, the by-product is in a multi-layer rod shape, and the number of layers of the by-product is in positive correlation 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 usually a common technical route in the industry. In the LED industry chain, the patterned sapphire substrate etching process usually uses plasma etching. Mass production involves multiple batches of etching. After a certain period of time, the etching chamber needs to be opened to clean the byproducts produced by etching on the top and side walls. Otherwise, the byproducts produced by etching will gradually increase over time and will inevitably fall off due to loose adhesion. Moreover, during batch operations, local etching byproducts often fall off and fall on the wafer due to loose adhesion, causing serious contamination and pattern damage to the wafer, 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 side walls 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 single layer thickness of the by-product, and the single layer thickness of the by-product is 1.35-2.5 μm.

[0011] Furthermore, in step S200: the upper RF power is 1000-2000W, the lower RF 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 RF power is 1000-2000W, the lower RF 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 comprises 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 by 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, 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 with the prior art, the present invention can achieve at least one of the following beneficial effects: the semiconductor substrate etching method of the present invention can effectively control the compactness and adhesion of etching byproducts, improve the drop of byproducts in the chamber during etching, almost avoid the drop of byproducts during etching, extend the operation time of a cycle, and improve the production capacity of plasma etching batch operations. A cycle of the present invention can be extended to 200 to 260 hours, and an etching batch of a cycle includes 350 to 400 times, which is 1 to 1.3 times longer than the cycle of the existing ordinary semiconductor substrate etching method, and the number of etchings is increased by 1 to 1.3 times.

[0023] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The 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 components throughout the drawings.

[0025] Figure 1 This is a SEM image of the by-product 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 byproduct 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 the by-product 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 byproduct formed by the etching method of the present invention in a specific embodiment;

[0031] Figure 7 It is a SEM image of the byproduct 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] Fig. 9 The SEM images of byproducts of etching batches 360 times at different magnification ratios in a specific embodiment;

[0034] Fig.10 The SEM images of byproducts of 90 etching batches at different magnification ratios in a specific embodiment;

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

[0036] Fig.12 The following are SEM images and elemental analysis images 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 in conjunction with 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 clearly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection, which can be a mechanical connection, or an electrical connection, which can be a direct connection, or can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

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

[0040] The common 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 plane and used on the horizontal plane, 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 at least be used 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 byproducts generated by the semiconductor substrate etching method are tightly adhered to the top and / or side walls 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.

[0048] The present invention evaluates the compactness of the by-product by the thickness of the single layer of the by-product. 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 byproducts is the same as the number of etching batches.

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

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

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

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

[0054] S101: cleaning the sapphire flat sheet;

[0055] S102: coating photoresist on one side of the sapphire flat sheet, and then forming photoresist columns by pattern transfer technology to obtain a 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 the sulfuric acid to the hydrogen peroxide is 3-6:1, the concentration of the sulfuric acid is 98.3%, and the concentration of the hydrogen peroxide is 30%.

[0057] In the step S102, the thickness of the photoresist coating is 0.2-5 μm. The pattern transfer technology can be exposure and development, or nanoimprinting. The photoresist column arrangement can be a periodic arrangement (square lattice arrangement, hexagonal close-packed arrangement), or a non-periodic quasi-crystalline arrangement, or a random arrangement.

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

[0059] In step S200:

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

[0061] The Cl-based gas is a main etching gas, which may 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 Cl-based gas flow rate ranges from 60 to 150 sccm, and the C / F compound gas flow rate ranges from 9 to 45 sccm, that is, the C / F compound gas flow rate accounts for 15% to 30% of the Cl-based gas flow rate.

[0064] C / F compound gas has a great influence on the shape of etching byproducts and can change the structure of byproducts. The influencing factors are mainly the composition and structure differences of the byproducts. Specifically, C / F compound gas directly affects the F content of etching byproducts. When the proportion of F increases, the molecular structure of etching byproducts changes, the degree of agglomeration increases significantly, and the original loose structure gradually becomes a compact structure.

[0065] In step S300:

[0066] The upper RF power is 1000-2000W, the lower RF power is 100-1000W, and the temperature is set at -40-40°C.

[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% (including 20% ​​and 80%) of the total etching time. If it is lower than 20% or higher than 80%, the by-products will be too loose or too tight, which is not conducive to adhering to the top and side walls of the chamber and are easy to 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; 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 Figure 2 As shown; when the first etching time accounts for 60% of the total etching time, the thickness of the single layer of by-products is thin (about 1.44 μm) and dense, as shown 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 1.35 μm) and dense, as shown Figure 4 As shown; when the first etching time accounts for more than 80% of the total etching time (exemplarily 95%), the thickness of the single layer of byproducts is too thin (1.13 μm) and too dense, such as Figure 5 shown.

[0070] The thickness of the by-product decreases with the increase of the first etching time ratio (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 byproducts 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 byproducts are in the form of rods and gather together in the same direction. The single rod-shaped byproduct microscope (such as Figure 6 and Figure 7 ) and SEM (as shown Figure 8 As shown in FIG. 1 , 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. Fig. 9 As shown, the number of etching batches is 360 times, the total length of the byproduct is 513 μm, the single layer thickness is 1.44 μm, and the single layer thickness 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 single layer thickness is 1.63 μm, and the single layer thickness 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 protruding microstructure on the substrate surface, wherein the protruding microstructure can be conical, quasi-conical, quasi-truncated cone, quasi-polygonal cone or quasi-polygonal cone. The ratio of the bottom width to the height of the protruding 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 stage 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 rate 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 Fig.11 As shown in FIG. 1 , a conical protrusion microstructure is formed on the substrate surface, with a bottom width of 2.71 μm and a height of 1.79 μm. The byproducts generated by the above method are tightly adhered to the top and / or sidewall of the etching chamber. After multiple batches of etching, the morphology of the byproducts is as follows: Fig.12 As shown, the monolayer thickness of the byproduct is 1.44 μm. Fig.12 From the by-product element analysis diagram, it can be seen that the F atom ratio in the by-product obtained by the method of the present invention can reach 22%, while the F atom ratio in the conventional etching method is close to 0%, indicating that the method of the present invention can increase the ratio of F atoms in the by-product and change the composition and morphology of the by-product. The cleaning cycle of the example is 200 to 260 hours, and the etching batches that can be performed in one cleaning cycle are 350 to 400 times.

[0078] The present invention can form a preset pattern substrate and improve the adhesion of by-products, greatly reduce the probability of by-products falling in the chamber during the etching process, and extend the operating time of a cycle.

[0079] The present invention can effectively improve the situation of byproducts falling off by adjusting the etching steps and reduce the frequency of chamber cleaning. When the predetermined cycle is not reached and the byproducts fall off prematurely, the etching method of the present invention can also improve the adhesion of the byproducts and reduce the frequency of opening the chamber for cleaning in advance.

[0080] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope 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% to 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% to 80% of the total etching time; The byproducts generated by the semiconductor substrate etching method are tightly adhered to the top and / or side walls 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.

2. The semiconductor substrate etching method according to claim 1, characterized in that: The compactness of the byproduct is evaluated by the single layer thickness of the byproduct, and the single layer thickness of the byproduct is 1.35-2.5 μm.

3. The semiconductor substrate etching method according to claim 1, characterized in that: In step S200: the upper RF power is 1000-2000W, the lower RF power is 200-1000W, and the temperature is -40-40°C.

4. The semiconductor substrate etching method according to claim 3, characterized in that: 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.

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

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

7. The semiconductor substrate etching method according to claim 1, characterized in that: 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.

8. The semiconductor substrate etching method according to any one of claims 1 to 7, characterized in that: In step S100, the substrate is a sapphire substrate, and the method for preparing the sapphire substrate to be etched comprises 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 by pattern transfer technology to obtain a sapphire substrate to be etched.

9. The semiconductor substrate etching method according to claim 8, characterized in that: 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%.

10. The semiconductor substrate etching method according to claim 8, characterized in that: The thickness of the coated photoresist is 0.2 to 5 μm.

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