Groove and manufacturing method thereof

Abstract

The invention provides a trench and a manufacturing method thereof, and the method comprises the steps: providing a substrate, and forming a mask layer on the substrate; etching the mask layer to form a patterned mask layer, wherein the patterned mask layer exposes part of the substrate; removing the naturally formed oxide layer on the exposed substrate, and at least forming a protective layer at the bottom of the side wall of the patterned mask layer; and etching the substrate by taking the patterned mask layer and the protective layer as masks, and forming a groove in the substrate. According to the method, the protection layer is at least formed at the bottom of the side wall of the patterned mask layer before the substrate is etched, and the protection layer is used for protecting the substrate below the protection layer, so that the top of the groove has a smooth morphology when the groove is formed by etching the substrate with the patterned mask layer as a mask. In addition, the protection layer is formed while the exposed oxide layer naturally formed on the substrate is removed, special equipment does not need to be added, process steps do not need to be added, and the manufacturing cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuits, and in particular to a groove and a manufacturing method thereof. Background Art

[0002] After the deep trench is etched, there will be a "depression" at the contact position between the substrate and the mask layer at the top of the trench, forming a sharp corner (Notch) at the top of the trench. In the subsequent process, this sharp corner can easily reduce the isolation effect of the oxide layer of the power device chip, causing voltage breakdown and chip leakage.

[0003] Figure 1 This is a magnified schematic diagram of a scanning electron microscope cross section of a structure after a groove is formed in a substrate in the prior art. Please refer to Figure 1 As shown, a trench 14 is formed in the substrate 10 , and a sharp corner exists at the top of the trench 14 (please refer to the dotted line box).

[0004] In the prior art, the problem of the sharp corners at the top of the trench is generally solved by adding a shallow trench etching step. However, this method will also add a photolithography step and an etching step, resulting in an increase in cost. In addition, the problem of the sharp corners at the top of the trench can also be solved by adding a soft-etching step after the trench etching. However, this method requires the purchase of a dedicated machine model corresponding to the process, and also requires an additional mask cleaning process. There is no mature and reliable process for soft etching. Summary of the invention

[0005] The object of the present invention is to provide a groove and a method for manufacturing the same, wherein a protective layer is formed on the sidewall of a patterned mask layer before etching the substrate to protect the substrate thereunder, so that the top of the formed groove has a smooth morphology.

[0006] In order to solve the above technical problems, the present invention provides a method for manufacturing a groove, comprising the following steps:

[0007] providing a substrate, and forming a mask layer on the substrate;

[0008] Etching the mask layer to form a patterned mask layer, wherein the patterned mask layer exposes a portion of the substrate;

[0009] removing the naturally formed oxide layer on the exposed substrate and forming a protective layer at least at the bottom of the sidewall of the patterned mask layer; and

[0010] The substrate is etched using the patterned mask layer and the protective layer as masks to form a groove in the substrate.

[0011] Optionally, the method of removing the naturally formed oxide layer on the exposed substrate and forming a protective layer at least at the bottom of the side wall of the patterned mask layer includes: dry etching the oxide layer using a carbon fluorine gas, and forming a carbon-containing polymer protective layer at least at the bottom of the side wall of the patterned mask layer during the etching process.

[0012] Optionally, the protection layer is located on the entire side wall of the patterned mask layer, and the width of the protection layer gradually increases from the top to the bottom of the side wall.

[0013] Optionally, the ratio of the number of carbon atoms to that of fluorine atoms in the carbon-fluorine gas is greater than 1:4.

[0014] Optionally, the carbon fluorine gas includes CHF3, CH2F2, or CH3F.

[0015] Optionally, in the dry etching, the pressure of the chamber is 10 mtorr to 30 mtorr, the upper electrode power is 600 w to 1000 w, the lower electrode bias voltage is 100 V to 200 V, and the reaction time is 8 s to 30 s.

[0016] Optionally, the method of etching the mask layer to form a patterned mask layer includes:

[0017] forming a photoresist layer on the mask layer;

[0018] Exposing and developing the photoresist layer to form a patterned photoresist layer;

[0019] Using the patterned photoresist layer as a mask, etching the mask layer until a portion of the substrate is exposed; and

[0020] The patterned photoresist layer is removed.

[0021] Optionally, the mask layer is over-etched until the mask layer is completely removed.

[0022] Optionally, the material of the mask layer includes silicon oxide, silicon nitride or silicon oxynitride.

[0023] Optionally, after forming the groove, the manufacturing method further includes: removing the mask layer and the protective layer.

[0024] Accordingly, the present invention further provides a groove, which is manufactured by the above-mentioned groove manufacturing method, and the groove comprises:

[0025] substrate;

[0026] A patterned mask layer is located on the substrate;

[0027] A protective layer, at least located at the bottom of the sidewall of the patterned mask layer; and

[0028] A groove is located in the substrate not covered by the patterned mask layer and the protection layer.

[0029] In the groove and its manufacturing method provided by the present invention, a substrate is first provided, a mask layer is formed on the substrate, and then the mask layer is etched to form a patterned mask layer, the patterned mask layer exposes part of the substrate, and then the naturally formed oxide layer on the exposed substrate is removed, and at least a protective layer is formed at the bottom of the side wall of the patterned mask layer, and then the substrate is etched with the patterned mask layer as a mask to form a groove in the substrate. The present invention forms a protective layer at least at the bottom of the side wall of the patterned mask layer before etching the substrate, and the protective layer is used to protect the substrate below it, so that when the substrate is etched with the patterned mask layer as a mask to form a groove, the top of the groove has a smooth morphology. In addition, the present invention forms the protective layer while removing the naturally formed oxide layer on the exposed substrate (i.e., performing the Breakthrough step), without adding special equipment or process steps, saving manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of an enlarged cross-section of a structure after a groove is formed in a substrate in the prior art using a scanning electron microscope.

[0031] Figures 2 to 7 It is a schematic diagram of the structures of the steps of a method for making a groove.

[0032] Figure 8 It is a schematic flow chart of a method for manufacturing a groove provided in one embodiment of the present invention.

[0033] Figures 9 to 11 It is a schematic structural diagram of each step of a method for manufacturing a groove provided in one embodiment of the present invention.

[0034] Fig.12 It is a schematic diagram of an enlarged cross-section of a structure of a groove provided by an embodiment of the present invention under a scanning electron microscope.

[0035] Description of reference numerals:

[0036] 10-substrate; 11-mask layer; 12-patterned photoresist layer; 13-patterned mask layer; 14-groove; 15-protective layer. DETAILED DESCRIPTION

[0037] Figures 2 to 7 This is a schematic diagram of the steps of a groove manufacturing method. Please refer to Figures 2 to 7As shown, the steps of forming a trench in a substrate generally include: first, forming a mask layer 11 on the substrate 10, forming a Figure 2 Then, a photoresist layer is formed on the mask layer 11, and the photoresist layer is exposed and developed to form a patterned photoresist layer 12, wherein the patterned photoresist layer 12 exposes a portion of the mask layer 11, and the exposed area is located above the area where the groove is predetermined to be formed on the substrate 10, forming a Figure 3 The structure shown; then, refer to Figure 4 As shown, the patterned photoresist layer 12 is used as a mask to etch the mask layer 11 to form a patterned mask layer 13, wherein the patterned mask layer 13 exposes a portion of the substrate 10, i.e., exposes an area on the substrate 10 where a groove is to be formed; thereafter, the patterned photoresist layer 12 is removed, and at this time, the exposed substrate 10 will naturally oxidize to form an oxide layer. Before etching the substrate 10, the naturally formed oxide layer needs to be etched, i.e., a BT (Breakthrough) step is performed, in which a carbon fluoride gas such as CF4 is introduced to perform a dry etching process to remove the oxide layer, forming a structure as shown in FIG. Figure 5 The structure shown; please refer to Figure 6 As shown, the substrate 10 is etched using the patterned mask layer 13 as a mask to form the groove 14 in the substrate 10. Figure 6 and Figure 7 As shown, the patterned mask layer 13 is removed.

[0038] However, in the process of etching the substrate 10 to form the trench 14, a sharp corner is easily formed on the top of the sidewall of the trench 14. Figure 7 As shown, a sharp corner is formed on the top of the sidewall of the trench 14, which may easily cause device leakage in the subsequent process.

[0039] Therefore, the sharp corners of the groove 14 need to be rounded, but the existing process for solving the sharp corners at the top of the groove will increase the process steps and add special equipment, thus increasing the manufacturing cost.

[0040] In response to the above problems, the present invention provides a groove and a method for manufacturing the same. After etching the mask layer to form a patterned mask layer exposing a portion of the substrate, the naturally formed oxide layer on the exposed substrate is removed (i.e., the Breakthrough step before etching the substrate, i.e., the BT step), and at the same time, a protective layer is formed at least at the bottom of the side wall of the patterned mask layer to protect the groove etching, so that the top of the formed groove has a smooth morphology.

[0041] Specifically, the present invention provides a method for manufacturing a groove, comprising the following steps: providing a substrate, forming a mask layer on the substrate; etching the mask layer to form a patterned mask layer, wherein the patterned mask layer exposes a portion of the substrate; removing the naturally formed oxide layer on the exposed substrate, and forming a protective layer at least at the bottom of the side wall of the patterned mask layer; and etching the substrate using the patterned mask layer as a mask to form a groove in the substrate.

[0042] The present invention also provides a groove, comprising: a substrate; a patterned mask layer located on the substrate; a protective layer located at least at the bottom of the side wall of the patterned mask layer; and a groove located in the substrate not covered by the patterned mask layer and the protective layer.

[0043] The present invention forms a protective layer at least at the bottom of the side wall of the patterned mask layer before etching the substrate, and the protective layer is used to protect the substrate below, so that when the substrate is etched to form a groove using the patterned mask layer as a mask, the top of the groove has a smooth morphology. In addition, the present invention forms the protective layer while removing the naturally formed oxide layer on the exposed substrate (i.e., performing the Breakthrough step), without adding special equipment or process steps, thus saving manufacturing costs.

[0044] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0045] As used in the present invention, the singular forms "one", "an" and "the" include plural objects, unless the content clearly indicates otherwise. As used in the present invention, the term "or" is generally used in a sense that includes "and / or", unless the content clearly indicates otherwise. As used in the present invention, the term "several" is generally used in a sense that includes "at least one", unless the content clearly indicates otherwise. As used in the present invention, the term "at least two" is generally used in a sense that includes "two or more", unless the content clearly indicates otherwise. In addition, the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features, unless the content clearly indicates otherwise.

[0046] Figure 8 FIG. 1 is a flow chart of a method for manufacturing a groove provided by an embodiment of the present invention. Figure 8 As shown, the method for making the groove comprises the following steps:

[0047] S1: providing a substrate, and forming a mask layer on the substrate;

[0048] S2: etching the mask layer to form a patterned mask layer, wherein the patterned mask layer exposes a portion of the substrate;

[0049] S3: removing the naturally formed oxide layer on the exposed substrate, and forming a protective layer at least at the bottom of the sidewall of the patterned mask layer; and

[0050] S4: etching the substrate using the patterned mask layer as a mask to form a groove in the substrate.

[0051] Figures 9 to 11 FIG. 1 is a schematic diagram of the structure of each step of the method for making a groove provided by an embodiment of the present invention. Figure 8 , Figures 2 to 4 , Figures 9 to 11 The method for manufacturing the groove provided in the embodiment of the present invention is described in detail.

[0052] In step S1, refer to Figure 2 As shown, a substrate 10 is provided, and a mask layer 11 is formed on the substrate 10 .

[0053] In some embodiments, the material of the substrate 10 may be silicon, germanium, silicon germanium, silicon carbide, gallium arsenide, indium gallium, etc., or may be silicon on insulator, germanium on insulator; or may be other materials, such as III-V compounds such as gallium arsenide. In this embodiment, the substrate 10 is a silicon substrate.

[0054] A mask layer 11 is formed on the substrate 10. The material of the mask layer 11 may include silicon oxide, silicon nitride or silicon oxynitride, or any other suitable material known to those skilled in the art. The mask layer 11 may be a single-layer structure, or a stacked structure of two or more layers. In one embodiment, the mask layer 11 is a single-layer structure including silicon oxide. The mask layer 11 may be formed by any suitable process known to those skilled in the art, such as an atomic layer deposition process, a chemical vapor deposition process, a physical vapor deposition process, etc.

[0055] In step S2, please refer to Figure 4 As shown, the mask layer 11 is etched to form a patterned mask layer 13 , and the patterned mask layer 13 exposes a portion of the substrate 10 .

[0056] In one embodiment of the present invention, the method of etching the mask layer 11 to form the patterned mask layer 13 may include: firstly forming a photoresist layer (not shown) on the mask layer 11; then referring to Figure 3 As shown, the photoresist layer is exposed and developed to form a patterned photoresist layer 12, wherein the patterned photoresist layer 12 exposes a portion of the mask layer 11, and the projection of the exposed area on the substrate 10 coincides with the area where the groove is to be formed on the substrate 10; then, the mask layer 11 is etched using the patterned photoresist layer 12 as a mask until a portion of the substrate 10 is exposed, thereby forming a patterned photoresist layer 12 as shown. Figure 4 The structure shown; then the patterned photoresist layer 12 is removed, for example, by an ashing process or a wet etching process to remove the patterned photoresist layer 12.

[0057] Exemplarily, the mask layer 11 may be etched by dry etching process, and the etching gas may be, for example, CF4 or CHF3 or other fluorine-carbon gas. In one embodiment of the present invention, the mask layer 11 is overetched until the mask layer 11 is completely removed, such as Figure 4 As shown, when the mask layer 11 is over-etched, the exposed substrate 10 will be slightly etched, that is, after the mask layer 11 is etched to form a patterned mask layer 13, a groove exposing a portion of the substrate 10 is formed in the patterned mask layer 13, and the bottom of the groove is located in the substrate 10.

[0058] In step S3, please refer to Fig. 9 As shown, the naturally formed oxide layer on the exposed substrate 10 is removed, and a protection layer 15 is formed at least at the bottom of the sidewall of the patterned mask layer 13 .

[0059] After the patterned mask layer 13 is formed and a portion of the substrate 10 is exposed, the exposed surface of the substrate 10 will be naturally oxidized to form an oxide layer, which needs to be removed before etching the substrate 10, i.e., performing a BT step. In this embodiment, a protective layer 15 is formed at least at the bottom of the sidewall of the patterned mask layer 13 when performing the BT step.

[0060] In one embodiment of the present invention, a carbon fluorine gas is used to dry-etch the oxide layer, and during the etching process, a carbon-containing polymer protective layer is formed at least at the bottom of the side wall of the patterned mask layer 13. Compared with only performing the BT step, the carbon content in the carbon fluorine gas can be appropriately increased to form a carbon-containing polymer protective layer on the side wall of the patterned mask layer 13. Exemplarily, the ratio of the number of carbon atoms to fluorine atoms in the carbon fluorine gas is greater than 1:4, that is, compared with CF4 used in only performing the BT step, the carbon content is increased, so that the carbon-containing polymer accumulates on the side wall of the patterned mask layer 13. In this embodiment, the carbon fluorine gas includes gases with a relatively high carbon content such as CHF3, CH2F2, or CH3F, but is certainly not limited to this.

[0061] In one embodiment of the present invention, the protective layer 15 is located on the entire sidewall of the patterned mask layer 13, and the width of the protective layer 15 (i.e. Fig. 9 The thickness in the horizontal direction) gradually increases, please refer to Fig. 9 As shown, the cross section of the protective layer 15 is triangular, but it is not limited thereto. The shape and width of the protective layer 15 can be determined by the specific etching gas (e.g., the carbon content in the etching gas) and the etching time. The protective layer 15 first gathers at the bottom of the side wall of the patterned mask layer 13 (i.e., the side wall of the groove in the patterned mask layer 13). As time accumulates, the aggregation of the protective layer 15 increases, extending from the bottom of the side wall to the top.

[0062] In one embodiment of the present invention, during the dry etching, the pressure of the chamber may be 10 mtorr to 30 mtorr, the upper electrode power may be 600 w to 1000 w, the lower electrode bias voltage may be 100 V to 200 V, and the reaction time may be 8 s to 30 s. Exemplarily, the pressure of the chamber is, for example, 10mtorr, 15mtorr, 20mtorr, 25mtorr or 30mtorr, wherein the pressure of the chamber is preferably 20mtorr; the upper electrode power is, for example, 600w, 700w, 800w, 900w or 1000w, wherein the upper electrode power is preferably 800w; the lower electrode bias voltage is, for example, 100V, 150V or 200V, wherein the lower electrode bias voltage is preferably 150V; the reaction time is, for example, 8s, 10s, 15s, 20s, 25s or 30s, wherein the reaction time is preferably 20s, and of course it is not limited thereto, the longer the reaction time, the thicker the thickness of the carbon-containing polymer protective layer, and the reaction time can be adjusted according to actual needs. Among them, the upper electrode power is used to promote the dissociation of gas into plasma, and the lower electrode bias voltage guides the plasma super-substrate bombardment, and the values ​​of each process parameter can be specifically determined according to actual needs.

[0063] In this embodiment, please refer to Fig. 9 As shown, the protection layer 15 covers a portion of the substrate 10, and can include the substrate 10 thereunder in subsequent etching, so that the top of the trench formed by etching has a smooth morphology.

[0064] In another embodiment of the present invention, the protective layer 15 can be formed before the BT step. Exemplarily, after the patterned mask layer 13 is formed, the protective layer 15 is formed on the sidewalls of the patterned mask layer 13. For example, a carbon-containing polymer protective layer can be formed on the sidewalls by a deposition process using fluorinated gases such as C4F8 and C4F6. After the protective layer 15 is formed, a BT step is performed to remove the oxide layer naturally formed on the substrate 10. In addition, since the BT step is performed to etch the oxide layer after the protective layer 15 is formed, the protective layer 15 may be etched in the BT step. Therefore, when forming the protective layer 15, it is necessary to appropriately increase the thickness of the protective layer 15 to prevent it from being completely removed in the BT step.

[0065] In step S4, please refer to Fig.10 As shown, the substrate 10 is etched using the patterned mask layer 13 and the protective layer 15 as masks to form a groove 14 in the substrate 10 .

[0066] In this embodiment, a dry etching process can be used to etch the substrate 10. The etching gas can be, for example, a mixed gas including chlorine (Cl2) and hydrogen bromide (HBr), or a mixed gas including sulfur hexafluoride (SF6) and oxygen (O2). Of course, other gases known to those skilled in the art for etching semiconductor substrates can also be used. In one embodiment, sulfur hexafluoride (SF6) and oxygen (O2) are used as etching gases to etch the substrate 10.

[0067] Due to the protection of the protection layer 15 , when the substrate 10 is etched with the patterned mask layer 13 as a mask to form the groove 14 , the top of the groove 14 has a smooth morphology.

[0068] Fig.12 This is a schematic diagram of a magnified cross-section of a groove structure provided by an embodiment of the present invention using a scanning electron microscope. Fig.12 As shown, the top of the groove 14 made by the groove making method of the present invention has a smooth morphology.

[0069] After forming the groove 14, the patterned mask layer 13 and the protective layer 15 are removed. Fig.10 and Fig.11As shown, the patterned mask layer 13 and the protective layer 15 are removed. Exemplarily, a wet etching process can be used to remove the patterned mask layer 13 and the protective layer 15. The etching solution used in the wet etching can be diluted hydrofluoric acid (HF). Of course, other etching solutions can also be used, such as EKC solution (the effective component of the EKC solution is hydroxylamine hydrochloride, or hydroxylamine and ammonia water, or a solution containing -NH2-OH groups), or BOE solution (formed by mixing 49% hydrofluoric acid aqueous solution and ammonium fluoride aqueous solution in proportion). Of course, other etching solutions known to those skilled in the art can also be used.

[0070] Since the protective layer 15 is formed while removing the oxide layer naturally formed on the substrate 10, and the protective layer 15 is removed while removing the patterned mask layer 13, the formation and removal of the protective layer 15 do not add any additional process steps and do not require the addition of special equipment. Compared with the method of solving the problem of sharp corners at the top of the groove in the prior art, the production cost is saved.

[0071] Correspondingly, the present invention also provides a groove, which is made by the groove making method as described above. Fig.10 As shown, the groove provided by the embodiment of the present invention includes:

[0072] Substrate 10;

[0073] A patterned mask layer 13 is located on the substrate 10;

[0074] A protective layer 15, at least located at the bottom of the sidewall of the patterned mask layer; and

[0075] The trench 14 is located in the substrate 10 that is not covered by the patterned mask layer 13 and the protection layer 15 .

[0076] In one embodiment of the present invention, the protective layer 15 is a carbon-containing polymer protective layer.

[0077] In one embodiment of the present invention, the protective layer 15 is located on the entire sidewall of the patterned mask layer 13, and the width of the protective layer 15 (i.e. Fig.10 The thickness in the horizontal direction gradually increases. Exemplarily, the cross section of the protective layer 15 is triangular, but it is not limited thereto.

[0078] In the embodiment of the present invention, due to the protection of the protection layer 15 , the top of the formed groove 14 has a smooth morphology.

[0079] In summary, in the groove and its manufacturing method provided by the present invention, a substrate is first provided, a mask layer is formed on the substrate, and then the mask layer is etched to form a patterned mask layer, the patterned mask layer exposes part of the substrate, and then the naturally formed oxide layer on the exposed substrate is removed, and at least a protective layer is formed at the bottom of the side wall of the patterned mask layer, and then the substrate is etched with the patterned mask layer as a mask to form a groove in the substrate. The present invention forms a protective layer at least at the bottom of the side wall of the patterned mask layer before etching the substrate, and the protective layer is used to protect the substrate below it, so that when the substrate is etched with the patterned mask layer as a mask to form a groove, the top of the groove has a smooth morphology. In addition, the present invention forms the protective layer while removing the naturally formed oxide layer on the exposed substrate (i.e., performing the Breakthrough step), without adding special equipment or process steps, saving manufacturing costs.

[0080] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for making a groove, characterized in that: The following steps are involved: providing a substrate, and forming a mask layer on the substrate; Etching the mask layer to form a patterned mask layer, wherein the patterned mask layer exposes a portion of the substrate; Removing the naturally formed oxide layer on the exposed substrate and forming a protective layer at least at the bottom of the sidewall of the patterned mask layer; as well as The substrate is etched using the patterned mask layer and the protective layer as masks to form a groove in the substrate.

2. The method for making a groove according to claim 1, characterized in that: The method of removing the naturally formed oxide layer on the exposed substrate and forming a protective layer at least at the bottom of the side wall of the patterned mask layer includes: dry etching the oxide layer using carbon fluorine gas, and forming a carbon-containing polymer protective layer at least at the bottom of the side wall of the patterned mask layer during the etching process.

3. The method for making a groove according to claim 2, characterized in that: The protection layer is located on the entire side wall of the patterned mask layer, and the width of the protection layer gradually increases from the top to the bottom of the side wall.

4. The method for making a groove according to claim 2, characterized in that: The ratio of the number of carbon atoms to that of fluorine atoms in the carbon-fluorine gas is greater than 1:

4.

5. The method for making a groove according to claim 4, characterized in that: The carbon fluorine gas includes CHF3, CH2F2, or CH3F.

6. The method for making a groove according to claim 5, characterized in that: In the dry etching, the pressure of the chamber is 10mtorr to 30mtorr, the power of the upper electrode is 600w to 1000w, the bias voltage of the lower electrode is 100V to 200V, and the reaction time is 8s to 30s.

7. The method for making a groove according to claim 1, characterized in that: The method of etching the mask layer to form a patterned mask layer includes: forming a photoresist layer on the mask layer; Exposing and developing the photoresist layer to form a patterned photoresist layer; Using the patterned photoresist layer as a mask, etching the mask layer until a portion of the substrate is exposed; and The patterned photoresist layer is removed.

8. The method for making a groove according to claim 7, characterized in that: The mask layer is overetched until the mask layer is completely removed.

9. The method for manufacturing a groove according to any one of claims 1 to 8, characterized in that: The material of the mask layer includes silicon oxide, silicon nitride or silicon oxynitride.

10. The method for manufacturing a groove according to any one of claims 1 to 8, characterized in that: After forming the trench, the manufacturing method further includes: removing the mask layer and the protection layer.

11. A groove, characterized in that: The groove is manufactured by the method for manufacturing the groove according to any one of claims 1 to 10, wherein the groove comprises: substrate; A patterned mask layer is located on the substrate; A protective layer, at least located at the bottom of the sidewall of the patterned mask layer; and A groove is located in the substrate not covered by the patterned mask layer and the protection layer.

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